Federal Agency for Education

State educational institution of higher professional education

NIZHNY NOVGOROD STATE TECHNICAL UNIVERSITY

Dzerzhinsky Polytechnic Institute

Department of "Machines and apparatus of chemical and food technologies"

EXPLANATORY NOTE

FOR COURSE WORK IN THE DISCIPLINE

"HYDRAULICS AND HYDRAULIC MACHINES"

OPTION 1.5

Completed by a student of group 04-MAPP

Kabanshchikov D.

Project manager Sukhanov D.E.

The project is protected with a rating of ____________

Dzerzhinsk

Introduction

1. Initial data for calculation

2. Pumping installation diagram

Initial information form

4. Calculation of hydraulic characteristics of the circuit

4.1 Calculation of pipeline diameters

2 Pressure loss in the pipeline

3 Calculation of hydraulic resistance along the common branch

3.1 Head loss due to friction

3.2 Calculation of losses due to local resistance

4 Calculation of hydraulic resistance for 1 branch

4.1 Head loss due to friction

4.2 Calculation of losses due to local resistance

5 Calculation of hydraulic resistance for 2 branches

5.1 Head loss due to friction

5.2 Calculation of losses due to local resistance

6 Calculation of hydraulic resistance for 3 branches

6.1 Head loss due to friction

4.6.2 Calculation of losses due to local resistance

7 Selecting a standard hydraulic machine

Appendix 1: Specification for the pump drawing

Introduction

A hydraulic machine is a machine that communicates the fluid flowing through it. mechanical energy(pump), or receive part of the energy from the liquid and transfer it to the working body for beneficial use (hydraulic motor).

The operation of a pump is characterized by its flow, pressure, power, efficiency and rotation speed.

Supply - fluid flow through the pressure (outlet) pipe.

Pressure is the difference in energy per unit weight of liquid in the flow section after the pump and in front of it:

Н = zн - zв + (pн - pв)/(ρg) + (υн2 - υн2) /(2g).

Power is the energy supplied to the pump from the engine per unit of time:

Pump efficiency is the ratio of useful power to consumed power:

η = Nп/N.

Graphic dependences of pressure, shaft power and pump efficiency on its performance at constant number revolutions are called pump characteristics. When choosing a pump, it is necessary to take into account the characteristics of the network, that is, the pipeline and devices through which the liquid is pumped. The network characteristic expresses the relationship between the fluid flow rate Q and the pressure H required to move the fluid through a given network. The head can be defined as the sum of the geometric height of the supply Hg and the pressure loss hp. The point where the characteristics intersect is called the operating point. It corresponds to the highest pump performance when operating on a given network. If higher performance is required, it is necessary to either increase the speed of the electric motor or replace this pump with a pump of higher capacity. The pump must be selected so that the operating point corresponds to the required performance and pressure in the area of ​​greatest efficiency.

In order to change the operating mode of the pump, it is necessary to change the characteristics of the pump or pumping unit. This change in characteristics to ensure the required flow is called regulation.

Regulation by valve (throttle)

Let us assume that the pump should have a flow not QA, corresponding to point A of the intersection of the pump characteristic with the characteristic of the pumping unit, but QB (Fig. 1). Let QB< QA. Этой подаче соответствует рабочая точка В характеристики насоса. Для того чтобы характеристика насосной установки пересекалась с кривой напоров Н = f(Q) в точке В, необходимо увеличить потери напора в установке. Это осуществляется прикрытием регулирующей задвижки, установленной на напорном трубопроводе. В результате увеличения потерь напора в установке характеристика насосной установки пойдет круче и пересечет кривую напоров Н = f(Q) насоса в точке В. При этом режиме напор насоса складывается из напора НBy , расходуемого в установке при эксплуатации с полностью открытой задвижкой, и потери напора в задвижке hз.:

НB = НBy + hз.

Thus, regulating pump operation by throttling causes additional energy losses that reduce the efficiency of the installation. Therefore, this method of regulation is uneconomical. However, due to its exceptional simplicity, throttling control has become most widespread.

Picture 1. Pump regulation by throttling

Regulation by changing the pump speed

Changing the pump speed leads to a change in its characteristics and, consequently, to a change in operating mode (Fig. 2). To implement regulation by changing the speed, motors with variable speed are required.

Such motors are DC electric motors, steam motors and gas turbines and internal combustion engines. Most common asynchronous electric motors with a squirrel-cage rotor, they practically do not allow changes in the speed. A change in the number of revolutions is also used by including a resistance in the rotor circuit of an asynchronous motor with a phase rotor, as well as a fluid coupling installed between the motor and the pump.

Regulating the operation of the pump by changing its speed is more economical than regulating it by throttling. Even the use of fluid couplings and resistance in the rotor circuit of an asynchronous motor, associated with additional power losses, is more economical than throttling control.

Figure 2. Pump control by changing the speed.

Bypass control

It is carried out by bypassing part of the liquid flow supplied by the pump from the pressure pipeline to the suction pipeline through a bypass pipeline on which the valve is installed. When the degree of opening of this valve changes, the flow rate of the bypassed liquid and, consequently, the flow rate in the external network changes. The energy of the fluid passing through the bypass pipeline is lost. Therefore, bypass control is uneconomical.

Adjustment by turning the blades

It is used in medium and large rotary vane axial pumps. When the blades are turned, the characteristics of the pump and, consequently, its operating mode change (Fig. 3). The efficiency of the pump changes only slightly when the blades are turned, so this control method is much more economical than throttling control.

Figure 3. Adjusting the pump by changing the angle of the blades.

The least power is obtained when regulating by changing the speed, slightly more power is obtained when regulating by throttling, the highest is obtained when regulating bypass: NB rev< NBдр < NB пер. Этот результат справедлив лишь для насосов, у которых с увеличением подачи мощность увеличивается (тихоходные и нормальные центробежные насосы). Если с увеличением подачи мощность уменьшается (например, осевые насосы), то регулирование перепуском экономичнее регулирования дросселированием.

Figure 4. Cost Comparison different ways pump regulation

1 Initial data for calculation

Section lengths:= 4 m; l2 = 8 m; l3 = 10 m; l4 = 0.5 m; l5 = 1 m; l6 = 1 m.

Markings for installation of receiving tanks: = 2 m; z2 = 4 m; z3 = 6 m.

Free pressure at consumption points: = 3 m; H2= 3 m; H3= 2 m.

Liquid flow rates in areas: = 100 m3/h; Q2= 200 m3/h; Q3= 50 m3/h.

Diffuser opening angle α = 60º.

Heat exchanger length Ltr = 1.8 m.

Diameter of the expansion tank dр = 0.6 m.

3. Initial information form

Number of branches - 3.

The condition of the pipes is with slight corrosion.

Fittings, devices installed in branches	General branch
1. Two-pipe heat exchanger (“pipe in pipe”)
2. Normal valve
3. Sharp turn
4. Smooth turn
5. Pipe entrance
6. Exit from the pipe
7. Sudden expansion
8. Sudden contraction
9. Confused
10. Diffuser
11. Coil
12. Shell and tube heat exchanger
13. Flow Q, m3/h
14. Branch length l, m
15. Markings for installation of receiving tanks, m
16. Free pressure at consumption points, H, m

Characteristics of local resistances

Two-pipe heat exchanger (“pipe in pipe”): branch 3, length of heat exchange sections - 1.8 m, number of sections - 4.

Flip flop:

branch 1, angle 90º,

branch 1, angle 90º,

branch 2, angle 90º,

branch 3, angle 90º,

branch 3, angle 90º,

branch 3, angle 90º,

branch 3, angle 90º,

branch 3, angle 90º,

branch 3, angle 90º,

branch 3, angle 90º,

branch 3, angle 90º.

Pipe entrance:

common branch, entry angle 0°,

common branch, entry angle 0°,

branch 1, entry angle 0°,

branch 3, entry angle 0°.

Exit from the pipe:

common branch, exit angle 0°,

branch 1, exit angle 0º,

branch 2, exit angle 0º,

branch 3, exit angle 0º.

Sudden expansion:

common branch, expansion tank diameter dр = 0.6 m.

Sudden contraction:

branch 2, expansion tank diameter dр = 0.6 m.

Diffuser:

branch 2, opening angle α = 60º.

4. Calculation of hydraulic characteristics of the circuit

Calculation of the hydraulic parameters of the circuit is necessary to determine the energy costs for moving fluid and selecting a standard hydraulic machine (pump).

1 Calculation of pipeline diameters

The given technological scheme contains containers located at various elevations, a centrifugal pump and a complex branched pipeline with shut-off and control valves installed on it and including a number of local resistances. It is advisable to start the calculation by determining the diameters of the pipeline using the formula:

di = √ 4Qi /(πw) , (1)

where Qi is the medium flow rate for each branch, m3/s;

wi - fluid speed, m/s.

To find the flow rate of the common branch Q0, m3/h, use the following formula:

where Qi is the flow rate of the corresponding branch, m3/h.

Q0 = Q1 + Q2 + Q3 = 100 + 200 + 50 = 350 m3/h.

To carry out calculations, the flow rate Qi is converted from m3/h to m3/s:

Q0 = 350 m3/h = 350/3600 = 0.097 m3/s,

Q1 = 100 m3/h = 100/3600 = 0.028 m3/s,

Q2 = 200 m3/h = 200/3600 = 0.056 m3/s,

Q3 = 50 m3/h = 50/3600 = 0.014 m3/s.

In practice, for media pumped by pumps, it is recommended to take an economic speed value of ≈ 1.5 m/s.

The diameters of pipelines along branches are calculated using formula (1):

d1= (4 0.028)/(π 1.5) = 0.154 m = 154 mm,

d2= (4 0.056)/(π 1.5) = 0.218 m = 218 mm,

d3= (4 0.014)/(π 1.5) = 0.109 m = 109 mm,

d0= (4 0.097)/(π 1.5) = 0.287 m = 287 mm.

Based on the calculated values ​​of di, the nearest standard pipe diameter dсti is selected according to GOST 8732 - 78 for seamless hot-rolled steel pipes.

For the first branch, a seamless hot-rolled steel pipe with an outer diameter of 168 mm, with a wall thickness of 5 mm, made of steel 10, manufactured according to group B of GOST 8731 - 74:

Pipe 168x 5 GOST 8732 - 78

B10 GOST 8731 - 74

For the second branch, a seamless hot-rolled steel pipe with an outer diameter of 245 mm, with a wall thickness of 7 mm, made of steel 10, manufactured according to group B of GOST 8731 - 74:

Pipe 245x 7 GOST 8732 - 78

B10 GOST 8731 - 74

For the third branch, a seamless hot-rolled steel pipe with an outer diameter of 121 mm, with a wall thickness of 4 mm, made of steel 10, manufactured according to group B of GOST 8731 - 74:

Pipe 121x5 GOST 8732 - 78

B10 GOST 8731 - 74

For the general branch, a seamless hot-rolled steel pipe with an outer diameter of 299 mm, with a wall thickness of 8 mm, made of steel 10, manufactured according to group B of GOST 8731 - 74:

Pipe 299x 8 GOST 8732 - 78

B10 GOST 8731 - 74.

Calculations of internal diameters di, mm, are made according to the formula:

di = Di - 2 b, (3)

where Di is the outer diameter of the corresponding pipeline, m;

b - wall thickness, m.

d0 = 299-2 8 = 283 mm = 0.283 m,

d1 = 168-2 5 = 158 mm = 0.158 m,

d2 = 245-2 7 = 231 mm = 0.231 m,

d3 = 121-2 4 = 113 mm = 0.113 m.

Since the internal diameters of standard pipes differ from the values ​​calculated using formula (1), it is necessary to clarify the fluid flow speed w, m/s, using the formula:

wi = 4·Qi/(π·d2сti), (4)

where dсi is the calculated standard internal diameter for each pipeline branch, m;

Qi is the flow rate of the medium for each branch, m3/s.

w0 = (4 · 0.097)/(π · (0.283)2) = 1.54 m/s,

w1 = (4 · 0.028)/(π · (0.158)2) = 1.43 m/s,

w2 = (4 · 0.056)/(π · (0.231)2) = 1.34 m/s,

w3 = (4 · 0.014)/(π · (0.113)2) = 1.4 m/s.

2 Pressure loss in the pipeline

Head losses are divided into friction losses along the length and local losses. Friction losses Δhi, m, occur in straight pipes of constant cross-section and arise proportionally to the length of the pipe. They are determined by the formula:

Δhtrain i = λi · (li/di) · (wi2/2g) (5)

where λi is the dimensionless friction loss coefficient along the length (Darcy coefficient);

g - acceleration free fall, m/s2.

The Darcy coefficient λi is determined by the universal formula of A. D. Altshul:

λi = 0.11 (Δi /di + 68/Rei)0.25, (6)

where Δi is the absolute equivalent roughness, depending on the condition of the pipes;

Rei - Reynolds number.

We select the absolute roughness of pipes as 0.2 mm for steel pipes that have been in use with slight corrosion.

The Reynolds number Re is calculated using the following formula:

Rei = (wi · di · ρ)/μ = (wi · di)/ν, (7)

where wi is the fluid flow speed through the corresponding pipeline, m/s;

di is the internal diameter of the corresponding pipeline, m;

ρ - liquid density, kg/m3;

μ - dynamic viscosity, Pa s,

ν - kinematic viscosity, m2/s.

Local losses are caused by local hydraulic resistance, that is, local changes in the shape and size of the channel, causing flow deformation. These include: sharp turns of the pipe (elbow), smooth turns, inlets and outlets of pipelines, sharp (sudden) expansions and contractions, confusers, diffusers, coils, heat exchangers, valves, etc.

Local pressure loss Δhм.с. i, m, are determined by the Weisbach formula as follows:

Δhм.с.i = ∑ξi (wi2/2g), (8)

where ξi is the resistance coefficient for various types of local resistance.

After calculating the components of pressure losses, the total losses Δhi, m, are determined by branches according to the formula:

Δhi = Δhtrain i + Δhm.s. i, (9)

where Δhtrain i - friction losses, m;

Δhм.с. i - losses due to local resistance, m.

Nfull i = Δho + Δhi + Hi + zi, (10)

where Hi is the free pressure at points of consumption, m;

zi - marks for installation of receiving tanks, m.

3 Calculation of hydraulic resistance along the common branch

3.1 Head loss due to friction

For the general branch of the pipeline, the Reynolds number is determined by formula (7):

Reо = (1.54 · 0.283)/(1.01 · 10-6) = 431505.

λо = 0.11 · (0.0002/0.283 + 68/431505)0.25 = 0.019.

Δhtrain = 0.019 · (1.5/0.283) · (1.54)2/(2 · 9.81) = 0.012 m.

pump hydraulic pipeline pressure

4.3.2 Calculation of losses due to local resistance

Two entrances to a pipe with sharp edges: ξin = 0.5.

Two valves are normal when fully open, with an internal diameter (taken as nominal diameter) of 283 mm. Since GOST does not indicate this conditional diameter and, accordingly, the valve resistance coefficient ξvent, interpolation is used to find it. IN in this caseξvent = 5.234.

Pipe outlet: ξout = 1.

Sudden expansion.

The resistance coefficient is selected depending on the ratio of the cross-sectional areas of the expansion tank and pipeline and the Reynolds number.

The ratio of the found cross-sectional areas is found through the ratio of the squares of the corresponding diameters:

F0/Fр = (d0/dр)2 = (0.283/0.6)2 = 0.223.

With a Reynolds number of 431505 and an area ratio of 0.223, the drag coefficient

ξext = 0.65.

For the general branch, the total pressure loss due to local resistance Δhм.с.о, m, is calculated using formula (8):

Δhм.с.о = (2 · 0.5 + 2 · 5.234 + 1+ 0.65) · (1.54)2/(2 · 9.81) = 1.59 m.

Total losses Δho, m, in the common branch according to formula (9):

Δho = 0.012 + 1.59 = 1.602 m.

4 Calculation of hydraulic resistance for 1 branch

4.1 Head loss due to friction

For the first branch of the pipeline, the Reynolds number is determined by formula (7):

Re1 = (1.43 · 0.158)/(1.01 · 10-6) = 223704.

λ1 = 0.11 · (0.0002/0.158 + 68/223704)0.25 = 0.022.

Friction losses are calculated using formula (5):

Δhtrain1 = 0.022 · (4/0.158) · (1.43)2/(2 · 9.81) = 0.058 m.

4.2 Calculation of losses due to local resistance

Let us determine the resistance coefficients ξ for a number of types of local resistances.

2. Two sharp turns of the pipe (elbow) with a rotation angle of 90°: ξkol= 1.

3. Two normal valves when fully open, with an internal diameter (taken as nominal bore) of 158 mm. Since GOST does not indicate this conditional diameter and, accordingly, the valve resistance coefficient ξvent, interpolation is used to find it. In this case, ξvent = 4.453.

Pipe outlet: ξout = 1.

For the first branch, the total pressure loss due to local resistance Δhм.с.1, m, is calculated using formula (8):

Δhм.с.1 = (0.5 + 2 1 + 4.453+ 1) (1.43)2/(2 9.81) = 0.829 m.

We determine the total losses Δh1, m, in the first branch using formula (9):

Δh1 = 0.058 + 0.829 = 0.887 m.

We determine the total pressure Nfull i, m, required to supply liquid through the branch using formula (10):

Nfull 1 = 1.602 + 0.887 + 3 + 2 = 7.489 m.

5 Calculation of hydraulic resistance for 2 branches

5.1 Head loss due to friction

For the second branch of the pipeline, the Reynolds number is determined by formula (7):

Re2 = (1.34 · 0.231)/(1.01 · 10-6) = 306475.

λ2 = 0.11 · (0.0002/0.231 + 68/306475)0.25 = 0.02.

Friction losses are calculated using formula (5):

Δhtrain 2 = 0.02 · (8/0.231) · (1.34)2/(2 · 9.81) = 0.063 m.

5.2 Calculation of losses due to local resistance

Let us determine the resistance coefficients ξ for a number of types of local resistances.

Sudden contraction.

The resistance coefficient is selected depending on the ratio of the cross-sectional areas of the expansion tank and pipeline, as well as the Reynolds number.

F2/Fр = (d2/dр)2 = (0.0231/0.6)2 = 0.148; Re = 306475>10000: ξin narrowing = 0.45.

The valve is normal when fully open, with an internal diameter (taken as nominal bore) of 231 mm. Since GOST does not indicate this conditional diameter and, accordingly, the valve resistance coefficient ξvent, interpolation is used to find it. In this case, ξvent = 4.938.

3. Sharp turn of the pipe (elbow) with a rotation angle of 90°: ξkol = 1.

Diffuser.

The diffuser resistance coefficient ξdiff is calculated using the following formula:

ξdif = λi/(8 sin(α/2)) [(F2′/F2)2 - 1]/ (F2′/F2)2 + sinα [(F2′/F2) - 1]/ (F2 ′/F2), (11)

where F2 is the cross-sectional area of ​​the pipeline before expansion, m2;

F2′ - cross-sectional area of ​​the pipeline after expansion, m2;

α - diffuser opening angle;

λi - Darcy coefficient. Calculated for a pipeline section with a smaller cross-section F2 (before expansion).

We accept the diameter of the pipeline after expansion independently, selecting the required standard diameter from GOST.

We accept a seamless hot-rolled steel pipe with an outer diameter of 273 mm, with a wall thickness of 7 mm, from steel 10, manufactured according to group B of GOST 8731-74:

Pipe 237x7 GOST 8732-78

B10 GOST 8731-74.

d2′ = 273 - 2 7 = 259 mm = 0.259 m.

Replacing the value F1/F0 equal to it (d1/d0)2, we get:

ξdif = λ2 /(8 sin(α/2)) [ (d2′ /d2)4 - 1]/(d2′ /d2)4 + sin(α) [(d2′ /d2)2 -1 ]/(d2′ /d2)2 = 0.02/(8 sin(60°/2)) ((0.259/0.231)4 - 1)/(0.2590/0.231)4 + sin(60° )·((0.259/0.231)2 - 1)/ 0.259/0.231)2 = 0.18.

5. Output from the pipe: ξout = 1.

For the second branch, the total pressure loss due to local resistance Δhм.с. 2 are calculated using formula (8):

Δhм.с.2 = (0.45 + 4.938 + 1 + 0.18 + 1) · (1.34)2/(2 · 9.81) = 0.69 m.

The total losses Δh2, m, in the second branch are determined according to formula (9):

Nfull2 = 1.602 + 0.756 + 4+ 3 = 9.358 m.

6 Calculation of hydraulic resistance for 3 branches

6.1 Head loss due to friction

For the third branch of the pipeline, the Reynolds number is determined by formula (7):

Re3 = (1.4 · 0.113)/(1.01 · 10-6) = 156634.

λ3 = 0.11 · (0.0002/0.113 + 68/156634)0.25 = 0.024.

Let us determine the Reynolds number at ν = 1.31·10-6 m2/s using formula (7):

Ret = (1.4 0.113)/(1.31 10-6) = 120763.

λt = 0.11 · (0.0002/0.113 + 68/120763)0.25 = 0.0242.

Friction losses are calculated using formula (5):

Δhtrain3 = 0.024 · (10/0.113) · (1.4)2/(2 · 9.81) + 0.0242 · (1/0.113) · (1.4)2/(2 · 9.81) = 0.234 m.

6.2 Calculation of losses due to local resistance

Let us determine the resistance coefficients ξ for a number of types of local resistances.

Entrance to a pipe with sharp edges: ξin = 0.5.

2. Eight sharp turns of the pipe (elbows) with a rotation angle of 90°: ξkol = 1.

2. The valve is normal when fully open, with an internal diameter (taken as nominal bore) of 113 mm. Since GOST does not indicate this conditional diameter and, accordingly, the valve resistance coefficient ξvent, interpolation is used to find it. In this case, ξvent = 4.243.

A “pipe-in-pipe” heat exchanger with liquid flowing through an internal pipe.

Resistance is calculated using the formula:

Δhт = λт · (Ltr/dtr) · (w2tr/2g) · m1 + ξ1 · (w2tr/2g) · m2, (12)

where the first term is friction losses,

where m1 is the number of direct heat exchange sections; the second is the loss due to local resistance due to smooth turns, ξ1 is the resistance coefficient for a smooth turn of 180°; m2 - number of turns.

The resistance coefficient for a smooth 180° turn ξ1 is calculated by the formula:

ξ1 = ξ1′ α°/90°, (13)

where ξ1′- is taken depending on the ratio d3/2 R0 = 0.6: ξ1′ = 0.44.

ξ1 = 0.44 180°/90°=0.88.

We calculate the resistance of the heat exchanger using formula (12):

Δhт = 0.0242 · (1.8/0.113) · ((1.4)2/(2 · 9.81)) · 4 + 0.88 · ((1.4)2/(2 · 9, 81)) 3 = 0.418 m.

Pipe outlet: ξout = 1.

For the third branch, the total pressure loss due to local resistance Δhм.с.3 is calculated using formula (8):

Δhм.с.3 = (0.5 + 8 1+ 4.243) (1.4)2/(2 9.81) + 0.418 = 1.691 m.

The total losses Δh3, m, in the third branch are determined according to formula (9):

Nfull3 = 1.602 + 1.925 + 2 + 6 = 11.53 m.

4.7 Selecting a standard hydraulic machine

To select a centrifugal hydraulic machine (pump), it is necessary to establish the performance and pressure that it must provide.

To ensure specified liquid flow rates to all points of consumption, the pump performance must meet the condition

Qus = ∑ Qi , (14)

us = max (Nfull). (15)

Total productivity Q = 350 m3/h.

To comply with condition (15), it is necessary to select the area with the highest required pressure by comparing various options, based on the mandatory supply of the necessary flow rates and the required free pressures. The area with the highest required pressure is taken as the base one, and it will determine the pump pressure. The pressure required to select a pump is Hpump = Hmax = Hfull 3 = 11.53 m.

The remaining branches can be converted to smaller pipe diameters in order to optimize the pipeline in terms of its cost, based on the condition:

Nfull1 = Nfull2 =...= Nfull. (16)

In most cases, such recalculation is not carried out, and the fulfillment of condition (16) is achieved by creating additional local resistance at the input of the corresponding section, as a rule, by installing a control valve.

When choosing a pump, it is also taken into account that the required operating modes of the pump (flow and pressure) must be within the operating range of its characteristics.

Based on the calculation of hydraulic parameters technological scheme The selected pump according to these characteristics is a horizontal cantilever pump with a support on a housing, brand K 200 - 150 - 250. Using the graphical characteristics, we clarify the correctness of the choice of pump.

For this pump:

The K 200 - 150 - 250 pump provides a flow of 315 m3/h, its productivity will be slightly higher - 20 m. A solution to this problem can be the use of the regulating effect of shut-off valves (valves installed on the pipeline) or the installation of additional (reserve) tanks, which due to the additional pressure of the liquid column, they will smooth out or completely eliminate the discrepancy between the required pressure and the pressure provided by the pump.

Cantilever pumps K

Purpose

Single-stage centrifugal cantilever pumps with a horizontal axial supply of liquid to the impeller, type K, are designed for pumping in stationary conditions clean water(except for sea water) with pH=6-9, temperature from 0 to 85°C (when using a double gland seal with water supplied to it up to 105°C) and other liquids similar to water in density, viscosity and chemical activity, containing solid inclusions by volume no more than 0.1% and up to 0.2 mm in size.

Used in water systems utilities, for irrigation, irrigation and drainage.

Description

The cantilever pump is, from a hydraulic point of view, a characteristic type of centrifugal pump, the working element of which is a centrifugal wheel. A centrifugal wheel consists of two disks, between which, connecting them into a single structure, there are blades that are smoothly curved in the direction opposite to the direction of rotation of the wheel.

When the wheel rotates, each particle of liquid located inside the wheel is affected by centrifugal force, directly proportional to the distance of the particle from the center of the wheel and the square angular velocity rotation of the wheel. Under the influence of this force, the liquid is ejected into the pressure pipeline from the impeller, as a result of which a vacuum is created in the center of the wheel, and increased pressure is created in its peripheral part.

The movement of liquid through the suction pipeline occurs due to the pressure difference above the free surface of the liquid in the receiving tank and in the central region of the wheel, where there is a vacuum.

In K-type pumps, torque is supplied from the electric motor shaft to the pump shaft through an elastic coupling.

The design of the pump according to the seal assembly is determined by the water temperature and pressure at the pump inlet. The single gland seal is not supplied with barrier fluid. When the water temperature is above 85°C or when the absolute pressure at the inlet is below atmospheric, barrier water is supplied to the double gland seal at a pressure exceeding the liquid pressure before the seal by 0.5-1 kgf/cm2. The barrier fluid (water) is supplied to a dead end into the double gland seal. The normal amount of external water leakage is up to 3 l/h; liquid must leak through the seal to lubricate the sealing surface.

The group of cantilever pumps includes centrifugal single-stage cast iron pumps with a one-way liquid supply to the impeller. The wheel of such a pump is located at the end of a shaft (console) fixed in the bearings of the pump housing or electric motor.

For the correct operation of centrifugal pumps and their selection when creating various pumping installations and stations, it is necessary to know how the main parameters of pumps change in different conditions their work. It is important to have information about changes in pressure H, power consumption N and pump efficiency η when its supply Q changes.

The selection of a pump for a given technological scheme is made from catalogs based on the calculation of the hydraulic parameters of the technological scheme. When choosing a pump, take into account that the required operating modes of the pump (flow and pressure) must be within the operating range of its characteristics.

Bibliography

1. Bashta T. M. Hydraulics, hydraulic machines and hydraulic drives. M.: Mechanical Engineering, 1982.

Shlipchenko Z. S. Pumps, compressors and fans. Kyiv, Technika, 1976.

Educational and methodological instructions for implementation course work in the discipline “Pumps and Compressors” for students of the specialty 05/17: Dzerzhinsk, 1995.

Selection of a pump for a given technological scheme for students of the specialty 17.05.: Dzerzhinsk, 1995.

Designation

Name

Documentation

Assembly drawing

Ring sealing

Working wheel

Tutorial

Putting the electric feed pump into operation after repair

Gruzdev V.B.

The method of preparation and start-up of a feed pump unit with an electric drive is considered. The sequence of technological operations when starting the feed pump and its oil system is described in detail. Given short description operation of centrifugal pumps in the network. The appendix provides illustrations explaining the operation of the feed pump. Options are also given emergency situations and their successful solution. Lists have been compiled test questions to each chapter.

Intended for full-time students - correspondence form training in preparation for specialty 140100 "Thermal Power Engineering". It may be useful for students of other specialties when studying the discipline “Operating Modes and Operation of Thermal Power Plants,” as well as all engineering and technical workers and workers of thermal and nuclear power plants.

electric centrifugal oil pump

Introduction

Chapter 1. Basic parameters and classification of pumps

3.3 Possible reasons emergency shutdown of a running oil pump

3.7 Security questions

4.4 Security questions

5.5 Security questions

Applications

Literature

Introduction

The purpose of this educational manual is student study general scheme piping and auxiliary equipment of the electric feed pump and its oil supply system, as well as their commissioning after repair.

When describing the electric feed pump and putting it into operation after repair with emergency situations, both the feed pump itself and its auxiliary systems, the well-known technical literature on pumps and more than 20 years of experience of the author in operating the Zainskaya State District Power Plant (Tatarstan), Leningradskaya and Chernobyl nuclear power plant, which made it possible to summarize and create this Manual, and thereby develop a methodology for preparing for start-up and putting electric feed pumps into operation after the repair of power units of thermal and nuclear power plants.

While studying the Manual, students will gain skills in solving operational problems when commissioning electrically driven feed pumps. Starting a feed pump with a turbo drive, where instead of a drive electric motor it is used steam turbine, does not differ significantly except for starting operations on the drive turbine. In the next Manual we will consider such a start-up of the feed pump, especially since it is equipped with turbo drives big park feed pumps of Russian and foreign power units with a capacity of 300 MW or more.

Now remember that pumps are hydraulic vane machines designed to lift and supply liquids, in our case - feed water from the deaerator.

Chapter 1. Basic parameters and classification of pumps

Terms in the field of pumps are established by GOST 17398-72 "Pumps. Terms and definitions". According to this GOST, pumps are divided into two main groups: dynamic and positive displacement.

Dynamic pumps are pumps in which fluid, under the influence of hydrodynamic forces, moves in a chamber (open volume) that is constantly connected to the inlet and outlet of the pump.

Positive displacement pumps are pumps in which fluid is moved by periodic change volume of the liquid chamber, alternately communicating with the inlet and outlet of the pump.

Dynamic pumps are divided into vane, friction and inertial pumps.

Vane pumps are pumps in which the liquid moves due to the energy transferred to it when flowing around the impeller blades. Vane pumps combine two main groups of pumps: centrifugal and axial. In centrifugal pumps, liquid moves through the impeller from the center to the periphery, and in axial pumps, through the impeller in the direction of its axis. Often pumps are supplied as a pump unit, i.e. a pump and a motor connected to it. The engine can be either electric or steam engines.

In addition, there is the concept of a pumping unit, i.e. a pumping unit with a set of equipment mounted according to a specific scheme that ensures the operation of the pump under given conditions.

In addition to terms related to the design and other characteristics of pumps, GOST 17398-72 also establishes the terminology of the main technical indicators of pumps and pumping units.

The main of these indicators is the volumetric flow of the pump - the volume of liquid supplied by the pump per unit time. Water supply is measured in m 3 /s or m 3 /h. It is allowed to measure flow in l/s.

There is a concept of mass supply - the mass of the supplied liquid per unit of time. Mass flow is measured in kg/s (t/s) or kg/h (t/h) and is determined as the second main indicator of the pump is the pressure or pressure it develops and is determined by the increase in the specific energy of water when its flow moves from the inlet to the outlet of the pump . Pressure is most often measured in meters of water column (m. water column) or in atmospheres (atm).

To determine the value of the total pump pressure H, the following formulas are used:

Н = P 2 /ρg – P 1 /ρg + Δh + (v 2 2 - v 2 1) / 2g, (m. water column) (1)

H = Hm+ (v 2 2 - v 2 1) / 2g, (m. water column), (2)

where P 2 , P 1 – water pressure in the pressure and suction pipes of the pump, respectively, atm;

Δh = (z 2 - z 1) –

vertical distance between the installation points of the pressure gauge on the pressure and the vacuum gauge on the suction, m;

v 2, v 1 - water speed in the discharge and suction pipes of the pump, m/s;

ρ is the density of water, kg/m3.

Hm is the manometric pressure of the pump, which is the sum of the readings of the pressure gauge at the pump pressure, the vacuum gauge at the suction, and the geometric pressure between the installation points of these devices Δh.

The pump head can also be expressed in terms of the water pressure at its outlet:

Р=Нρg, (m.water column) (3)

Pressure is measured in kPa, MPa, atm or kgf/cm2, and pressure is measured in meters of the column of pumped liquid. For example, a meter of water column is written as - m. water. Art., and 10 m. water. Art. = 1.0 atm. = 1.0 kgf/cm 2 = 0.1 MPa. The volumetric flow Q of the pump is measured in m 3 /s, and the mass flow M is measured in kg/s, which is defined as

where ρ is the density of the medium, kg/m3.

In turn, the volumetric flow is almost the same along the entire length of the pump flow path and can be calculated from the average speed of the medium using the flow continuity equation:

where F is the cross-sectional area of ​​the liquid flow, m2;

C is the speed of movement of the medium, m/s.

The amount of energy spent per unit of time to drive the pump determines its useful power:

Nп =ρg QH, (kW) (6)

Nп =ρQH / 102, (kW) (7)

where Q is pump performance, m 3 /s;

ρ – density of the medium, kg/m3;

N – total pump pressure, m. water column.

Energy losses are inevitable in any work process and the actual power expended to drive the pump is greater than the theoretical value:

N = Nп + ΔN, (8)

where ΔN is the sum of all energy losses arising due to the imperfection of the pump as a vane machine.

To assess the complete use of energy supplied to the pump from the engine, a characteristic called the effective efficiency of the unit is used:

Thus, knowing the efficiency, pressure and flow of the pump, you can calculate the power consumption of the pump:

N= ρgQH/η = Np / η, (kW) (10)

But a dimensionless quantity called the speed coefficient is very important for blade machines.

The speed factor ns is used to compare the geometric parameters and technical and economic indicators of similar pumps having different meanings pressure, flow and speed. Why is this necessary? The ns coefficient allows one pump to be replaced by another during design and operation, which is especially important at the present time. Physically, the speed coefficient is understood as the rotation frequency of a virtual model pump, geometrically similar in all elements to the full-scale one, with the same hydraulic and volumetric coefficients useful action provided that the model pump creates a pressure equal to 1 meter of water column with a hydraulic power of 1 hp, i.e. the flow rate of the model pump is Q = 0.075 m 3 /s at maximum efficiency mode, if we assume that the density of water is 1000 kg/m 3 under normal physical conditions.

It is known that the speed coefficient is a function of three arguments - productivity Q, pressure H and the number of revolutions n of the pump rotor, i.e. ns = f(Q, H, n), and evaluates optimal mode operation of the blade machine. With its help, it is also convenient to classify the type of pump according to the type of working body, evaluate the choice of the number of compression stages, and summarize technical and economic indicators various types pumps The formula for calculating ns was derived by full-scale modeling of processes in blade machines, i.e. empirically, and is written in the following form for pumps supplying water with density ρ=10 3 kg/m 3

ns= 3.65 n√Q/ H 3/4 , (11)

where n is the number of pump revolutions, rpm;

Q – pump flow (performance), m 3 /hour;

H - pump pressure, m. water. Art. (for multi-stage pumps with identical impellers, pressure per impeller).

Thus, the speed coefficient allows you to combine various wheels pumps into groups based on their geometric similarity and is a purely calculation parameter, with the help of which it is convenient to classify the type of pump by working parts, evaluate the choice of the number of stages for a multi-stage pump, and generalize the technical and economic indicators of various pumps.

The following classification of centrifugal pump impellers according to the speed coefficient is usually used:

1). low-speed, n s = 50-100;

2). normal, n s = 100-200;

3). high-speed, n s = 200-350

Let's give an example practical application speed factor. For example, we need to determine the number of stages of the selected feed pump with a flow rate Q = 650 m 3 /hour, a pressure of 2000 m of water. Art. (200 atm), speed n = 2850 rpm (drive from an asynchronous electric motor).

First, we determine the speed coefficient ns using formula (11), which will be equal to 663.

ns= 3.65 n√Q/ H 3/4.

Then ns= 3.65 x 2850 x √ 650 / 2000 3/4 = 663.16 ≈ 663.

Now we determine the pressure of one stage of pump H1 using the formula:

H1 = (3.65n √Q / ns) 3/4

Н1 = (3.65n √Q / ns) ¾ = (3.65 x 2850 x √650 / 663) ¾ = 400 m of water. Art.

By dividing the required total pressure of 2000 m of water. Art. per pressure of one stage, we get the number of stages of the selected feed pump - 2000 / 400 = 5 stages in the pump that satisfy the specified hydraulic requirements.

Pump selection is usually carried out for given operating conditions of the external network according to the required flow, pressure, temperature, as well as physical and chemical properties pumped liquid (corrosive properties, viscosity and density of the liquid). The flow and pressure of the pump must correspond to the hydraulic resistance characteristics of the external network, which consists of a pipeline system and fittings. In this case, the pump must provide the maximum possible flow for a given network. But taking into account possible deviations in the characteristics of the selected pump during its manufacture at the factory, we still select its pressure 3-5% higher than the required pressure to overcome the hydraulic resistance of the network. It is also important correct installation pump Pumps are sometimes installed so that the level of the suction pipe is above the liquid horizon in the receiving tank or chamber.

In such cases, it is necessary to create a vacuum (vacuum) in the inlet pipe of the pump, due to which the liquid will be sucked into the pump under the influence of column pressure atmospheric air. The suction lift developed by a vane pump is given by:

Hs = (P 0 - P 1) / ρg, (12)

where P 0 - Atmosphere pressure or pressure in the container to which the pump is connected, atm; ρ – liquid density, kg/m3; g – gravitational acceleration equal to 9.81 m/s 2

Pump catalogs always indicate the permissible vacuum suction height Hvs, i.e. the height at which the operation of this pump is ensured without changing its basic technical parameters. It is known that the reliability and stability of the operation of energy pumps depends on the permissible suction height. Therefore, let us briefly recall what the suction height of pumps is and especially the phenomenon of cavitation. The liquid is supplied through the suction pipeline to the pump impeller under the influence of the pressure difference in the receiving tank and the absolute pressure in the flow at the entrance to the impeller. The latter depends on the location of the pump relative to the surface level of the liquid in the tank and the operating mode of the pump. In practice, there are three main installation schemes for centrifugal pumps:

Rice. 1. Installation diagrams for centrifugal pumps

1. the pump axis is above the water level (0-0) in the receiving tank (chamber) – (Fig. 1, a);

2. The pump axis is below the water level (0-0) in the receiving tank (Fig. 1, b), i.e. the pump is under guaranteed water filling;

3. The pump axis is below the water level (0-0) in the receiving tank and it is under excess pressure (Fig. 1, c), so the pump is guaranteed to be filled with water. As follows from Fig. 1, the most in the best ways connecting the pump to a water source are options b) and c), because there is very high guarantee ensuring that the pump does not fail to operate, i.e. There will always be a backwater of water at the suction as long as there is an excess level at the pump inlet, and the most inconvenient method is option a). Here water must be driven into the pump, and for this it is necessary to create a vacuum at the entrance to the pump and put check valve on the suction pipeline, always fill the suction pipeline with water, while the check valve must hold this water and not release it from the pump. When the pump is turned on, it will create a vacuum at the suction and water will flow into the pump under the influence of atmospheric air pressure. When the pump is turned off, the check valve must not let water out of the pump and keep it in the pump cavity, otherwise, it will have to be filled with water again or the check valve repaired. As you can see, this is an inconvenient way to connect a pump, but it is used when you need to pump water from a well, underground tank or pit. In any case, all these methods are widely used both in power plants and other industrial enterprises and in everyday life.

From the Bernoulli equation for two sections (in our case, for the water level in the receiving tank 0 - 0 and the section at the inlet to the pump (Fig. 1.)) it follows:

Hg.v. + h p.v. = pa / ρg – pн / ρg- v 2 in / 2g, (13)

where h a.e. - losses in the suction pipeline, Pa;

pa - atmospheric pressure, Pa;

рв - absolute pressure at the pump inlet, Pa;

vв - water speed at the pump inlet, m/s.

The left side of equation (13) represents the vacuum suction height of the pump and is measured in meters of water column of the pumped liquid.

You can also write that the suction height of the pump Hb

Hв = H g.v. + h p.v. (14)

From the analysis of formulas (13, 14) it follows that if water enters the pump with backwater (Fig. 1, b), then

Hв = h p.v. -- H g.v. (15)

A negative value of H in indicates the pump is operating with support.

When the pump operates according to the diagram shown in Fig. (1, c), the expression for the vacuum suction height takes the form:

Hв = / ρg, (16)

where P 0 is the absolute pressure of the medium above the free surface of the liquid, Pa.

Depending on the design of the vane pump, the geometric suction height is calculated differently.

For horizontal pumps H g.v. - this is the difference between the elevations of the pump axis and the liquid level in the receiving tank.

For pumps with vertical shaft N g.v. measured from the middle of the inlet edges of the impeller blades (in multistage first-stage wheel pumps) to the free surface of the liquid in the receiving tank.

It must be remembered that normal operation of a centrifugal pump is ensured only in such a mode when the absolute pressure at all points of its internal cavity more pressure saturated vapor of the pumped liquid at a given temperature.

If this condition is not met, then the phenomena of vaporization and cavitation begin, which lead to a decrease or even termination of the pump supply (the pump “breaks”) and its failure.

Cavitation - s Latin language(cavitas) means emptiness. So what is this phenomenon under such a beautiful and sonorous name?

Cavitation is a process of disruption of continuity within a fluid flow, i.e. the formation in a droplet liquid of cavities filled with gas, steam or a mixture of them (cavitation bubbles or “cavities”, i.e. voids). Typically, cavitation flow is characterized by a dimensionless parameter (cavitation number):

, (17)

P - hydrostatic pressure of the oncoming flow, Pa;

P s - saturated vapor pressure of a liquid at a certain temperature environment, Pa;

ρ - density of the medium, kg/m³;

V is the flow velocity at the entrance to the system, m/s.

It is known that cavitation occurs when the flow reaches the boundary speed V = V c, when the pressure in the flow becomes equal to the pressure of vaporization (saturated vapor). This speed corresponds to the limit value of the cavitation criterion.

Depending on the value of Χ, four types of flows can be distinguished:

· pre-cavitation - continuous (single-phase) flow at Χ>1;

· cavitation - (two-phase) flow at Χ~1;

· film - with stable separation of the cavitation cavity from the rest of the continuous flow (film cavitation) at Χ< 1;

· supercavitation - at Χ<<1.

The required suction head Δh TP is usually calculated from the characteristic provided by the pump manufacturer. The Δh TP curve starts from the zero feed point and increases slowly as it increases. When the flow exceeds the pump's maximum efficiency point, the Δh TP curve rises sharply exponentially. The area to the right of the point of maximum efficiency is usually a cavitation hazard.

The cavitation reserve cannot be controlled from a mechanical point of view and the driver of the pumping station only hears it as metallic noise and clicks, but this is already developed cavitation.

Unfortunately, there are still few devices that allow one to observe and prevent cavitation. Although a pressure sensor on the suction side of the pump, which gives an alarm when the pressure drops below the permissible pressure for a given pump, should be used everywhere.

It is known from experience in operating pumps that the crackling sounds disappear after closing the pressure valve. But, thereby reducing flow and cavitation, the technological parameters of the pump itself may not be achieved.

In order to properly eliminate cavitation, it is imperative to use the basic principle - there must always be more liquid at the pump inlet than at the outlet.

Here are a few simple ways to achieve this:

1. Replace the diameter of the suction pipe with a larger one. It must be remembered that the suction diameter of the pump should always be greater than the pressure diameter;

2. move the pump closer to the water source or to the supply tank, but not closer than 5-10 diameters of the suction pipe;

3.reduce the resistance in the suction pipe by replacing its material with a less rough one;

4.replace the suction valve with a gate valve, characterized by lower local losses;

5. if the suction pipe has turns, then reduce their number or replace small bends with large turning radii, orienting them in the same plane (sometimes it is correct to replace a rigid pipe with a flexible one);

6. Increase the pressure on the suction side of the pump by raising the level in the supply tank or lowering the pump installation axis, or install a booster pump.

It is well known that cavitation occurs as a result of a local decrease in pressure below a critical value and for a real liquid it is approximately equal to the saturated vapor pressure of this liquid at a given temperature. As a result of this, the formation of a large number of tiny bubbles filled with liquid vapor and gases released from it is observed. The formation of bubbles looks like boiling liquid.

The bubbles that arise as a result of a decrease in pressure increase in size and are carried away by the flow.

In this case, a local increase in the speed of liquid movement is observed due to the restriction of the cross section of the flow by released bubbles of vapor or gas.

When entering an area with a pressure above critical, the bubbles are destroyed, and their destruction occurs at high speed and is therefore accompanied by local hydraulic shock in this microscopic zone. Since condensation occupies a certain area and occurs continuously over a long period of time, this phenomenon leads to the destruction of significant surface areas of the pump impellers or guide vanes.

In practice, the appearance of cavitation during pump operation can be detected by a characteristic crackling sound in the suction area, increasing noise and the sudden appearance of increased vibration of the pump. Cavitation is also accompanied by chemical destruction (corrosion) of the pump material under the influence of oxygen and other gases released from the liquid in the area of ​​​​low pressure.

With the simultaneous action of corrosion and cyclic mechanical stress, the strength of the metal parts of the pump quickly decreases. At the same time, the effect of cavitation on the metal parts of the pump increases if the pumped liquid contains suspended abrasive substances: sand, small slag particles, etc.

Under the influence of cavitation, the surfaces of parts become rough and spongy, which contributes to their rapid abrasion by suspended substances. In turn, these substances, abrading the surfaces of pump parts, contribute to increased cavitation.

Cast iron and carbon steel are most susceptible to cavitation damage, and bronze and stainless steel are the least susceptible.

Rice. 2. Destruction of the impeller of a centrifugal pump under the influence of cavitation

In order to increase the resistance of pump parts from destruction, protective coatings are used. To do this, the surfaces of the parts are overlaid with hard linings made of hard alloys (stellites), local surface hardening and other methods of protection are used. However, the main measure to combat premature wear of the pump flow part is to prevent cavitation modes of their operation.

The technical documentation for pumps (catalogues, passports, etc.) must indicate the permissible suction height (or permissible cavitation reserve) for normal physical conditions, i.e. for an atmospheric pressure of 0.1 MPa (which corresponds to 760 mm Hg. ) and the temperature of the pumped liquid is 20°C.

Therefore, the main technical characteristics that determine the operation of any pump are:

1. pressure (Nn, m. water column; atm.; kgf/cm2; Pa, kPa, MPa);

2. flow (Q, l/sec; m 3 /hour; kg/s; t/hour);

3. power consumption (N, kW);

4. efficiency (η,%);

5. rotation speed (n, rpm);

6. pump suction height (N sun, m. water column).

Of the indicated pump parameters, flow and rotation speed are independent variables, and the remaining parameters are functionally dependent on flow and rotation speed. The relationship between parameters in various pump modes is usually depicted graphically in the form of characteristics.

To obtain them, it is necessary to test the pump under different suction conditions, at different pressures, flows and powers, varying from minimum to maximum values. Only as a result of these tests can an idea of ​​the operation of the pump and its energy performance be obtained.

Experimental characteristics of the pump are necessary technical material for assessing the quality of the pump, for choosing its operating mode and for correct and reliable operation. These experimental characteristics are obtained by testing each pump at the manufacturer and are attached to the technical documentation when the pump is sold.

Here we will not consider the construction of normal and other characteristics of pumps, as well as the use of mathematical tools for calculating pumps, because this is not the task of our Manual, so we refer the inquisitive reader to the Literature, which is given at the end of the Manual.

Due to the nature of the physical and working process in the pump, the mechanical energy of the drive motor is converted into the hydraulic energy of the fluid being moved.

We already know that there are dozens of different types of pumps, but the main ones and often used in power plants are positive displacement and vane pumps. In positive displacement pumps, energy is transferred by the forced action of the working body (plunger, piston, rotor) on the transported medium and its displacement (plunger, piston, rotary pumps). In vane pumps, the conversion of mechanical energy into hydraulic energy is carried out by an impeller mounted on a rotating rotor shaft, equipped with blades (centrifugal, axial, vortex, diagonal pumps). At modern power plants, both in Russia and abroad, CBN - centrifugal pumps and OH - axial pumps are mainly used. Check valve on pump suction:

Rice. 3. Scheme of a centrifugal pumping unit

1 – open source of water;

2 – suction pipeline;

3 – open pressure reservoir;

4 – flow meter insert in the pressure pipeline;

5 – centrifugal pump;

6 – electric motor;

M – pressure gauge at pump pressure;

V – pressure and vacuum gauge at the pump suction;

P – atmospheric pressure.

In Fig. Figure 4 shows a section and structure of a conventional single-stage centrifugal pump.

Rice. 4. Scheme of a centrifugal pump

1 – expanding pump casing (“volute”);

2 – pump shaft;

3 – impeller;

4 – impeller blades;

5 – inlet (suction) pipe of the pump;

6 – outlet (pressure) pipe of the pump.

Inside the pump housing 1, which usually has a spiral shape in the form of a snail, an impeller 3 is mounted on a shaft 2. The impeller consists of rear and front disks, between which blades 4 are installed, bent from the radial direction in the direction opposite to the direction of rotation of the impeller wheels.

Using pipes 5 and 6, the pump body is connected to the suction and pressure pipelines. If, with the housing and suction pipeline filled with liquid, the impeller is rotated, then the liquid located in the channels of the impeller (between its blades) will be thrown from the center of the impeller to the periphery under the influence of centrifugal force. As a result, a vacuum is created in the central part of the wheel, and excess pressure is created at the periphery. Under the influence of this pressure, the liquid from the pump enters the pressure pipeline, and at the same time, through the suction pipeline, under the influence of vacuum, the liquid enters the pump. Thus, a continuous supply of liquid is carried out by a centrifugal pump.

Centrifugal pumps can be not only single-stage (with one impeller), as shown in Fig. 2, but also multi-stage (with several impellers). At the same time, the principle of their operation in all cases remains the same - the liquid moves under the action of the centrifugal force developed by the rotating impeller.

The so-called diagonal pumps, the design of which combines the features of centrifugal and axial pumps, have become widespread abroad. Unlike centrifugal pumps, in diagonal pumps the flow exits the impeller at an angle of 45° rather than 90°.

In diagonal pumps, the fluid flow passing through the impeller is directed not radially, as in centrifugal pumps, and not parallel to the axis, as in axial pumps, but obliquely, as if along the diagonal of a rectangle made up of radial and axial directions.

The inclined flow direction creates the main design feature of diagonal pumps - the arrangement of the impeller blades inclined to the pump axis. This circumstance makes it possible to use the combined action of lifting and centrifugal forces when creating pressure, and in terms of their operating parameters, diagonal pumps occupy an intermediate position between centrifugal and axial pumps.

Like central and axial pumps, diagonal pumps are available in both horizontal and vertical shafts.

Rice. 5. Section of a diagonal pump with a horizontal rotor

Rice. 6. Axial type pump

1 – pump housing; 2 – stationary guide device of the pump; 3 – rotating pump rotor; 4 – working blades of the pump rotor rotating around their own axis.

Rice. 7. Jet pump

1 – confuser on supply of stimulating medium (water, gas);

2 - pipe for sucked liquid (gas);

3 – working chamber for mixing the supplied and sucked media (vacuum chamber);

4 – diffuser part of the pressure-discharge part of the pump.

Rice. 8. Gear pump

1 – pump housing;

2 – suction part of the pump;

3 – safety-bypass valve;

4 – pressure part of the pump.

Rice. 9. Piston (plunger) pump

1 – pump housing;

2 – piston (plunger);

3 – cylinder;

4 – piston rod;

5 – crank;

6 – connecting rod;

7 – drive;

Kv – valve at the pump suction;

Kn – discharge valve on the pressure side of the pump

At thermal power plants, centrifugal hydraulic pumps are used as feed pumps, which have a very high pressure increase coefficient, especially multi-stage ones. Mechanical energy is supplied in the form of rotating torque and transmitted to the fluid through the blades of the rotating impeller. The action of the blades on the liquid filling the impeller causes an increase in hydrodynamic pressure and causes the liquid to move in the direction from the center of the impeller to the periphery, throwing it into the spiral casing. In further movement, the liquid enters the pressure pipeline. It follows that the main working body of a centrifugal pump is a blade wheel rotating freely inside the housing. In Fig. 10, 11 show photographs of the impeller of a centrifugal pump. In turn, the impeller consists of two vertical disks (front and rear along the fluid flow), as shown in Fig. 10, spaced at some distance from each other. Between the disks, connecting them into a single structure, there are blades, smoothly curved in the direction opposite to the direction of rotation of the wheel (Fig. 9), i.e. along the fluid flow. The inner surfaces of the disks and the surfaces of the blades form the inter-blade channels of the wheel, which during pump operation are filled with the pumped liquid.

Fig. 10. Cross-section of the impeller of a centrifugal pump

Rice. 11. Centrifugal pump impeller assembly

From the course of theoretical mechanics it is known that when the wheel rotates with an angular velocity ω (1/sec), a centrifugal force F c.b. will act on the elementary mass of liquid m (kg), located in the inter-blade channel at a distance R (m) from the shaft axis. . , defined by the expression:

F c.b = m ω 2 R(18)

In engineering calculations, formula (19) is also used, which is equivalent to formula (18):

F c.b = mV 2 / R, (19)

where V (m/s) is the linear speed of movement of the elementary mass of matter at a radius R from the center of rotation.

We have already said that to ensure the continuous movement of liquid through the pump, it is necessary to ensure its constant supply to the pump and removal from the pump. Therefore, the liquid enters through the hole in the front disk of the impeller through the suction pipe from the suction pipe.

For example, the movement of water through the suction pipeline into the feed pump occurs due to excess pressure in the deaerator housing and the feed water column, equal to the difference between the installation elevations of the deaerator accumulator tank and the installation elevation of the feed pump in the turbine room of the main building of the power plant.

The usual level for installing the accumulator tank of a block deaerator is 20÷24 meters in the deaerator shelf room of the power plant, depending on the power of the power unit, and the installation of the feed pump is carried out at the level of 0.0 ÷ 5.0 meters in the turbine hall of the main building of the power plant. It follows that the difference between the installation elevations of the deaerator accumulator tank and the feed pump can be 15.0 - 19.0 (24 - 5 = 19) meters and if we take into account the temperature and specific volume of feed water in the accumulator tank, as well as the hydraulic resistance of the feed water downpipe water to the suction of the feed pump, it turns out that the head pressure at the suction of the feed pump will be 13÷17 m of water. Art. or 1.3 -1.7 atm. This makes it possible to partially recover from the dangerous phenomenon of cavitation, having a guaranteed supply of feed water pressure at the suction of the feed pump. In Fig. 12 is a hydrostatic diagram of a feed pump to illustrate the above.

Rice. 12. Hydrostatic diagram of the feed pump

A – mark for installing the deaerator battery tank;

B – mark for installing the feed pump;

H1 – height of the feed water level in the deaerator battery tank;

H2 is the difference between the installation marks of the deaerator accumulator tank and the feed pump.

Analysis of equations (18,19) shows that the centrifugal force, and therefore the pressure developed by the pump, is greater, the higher the speed of rotation of the impeller.

But the increase in the rotation speed of the pump rotor is limited by the rotation speed of the electric motor, because Any high-speed electric motor is generally used to drive a centrifugal pump, but most often asynchronous-type electric motors, the speed of which is slightly lower than the synchronous speed, are used for this purpose.

The use of other electric motors, as well as electrical devices for regulating the speed of the electric motor, although they make it possible to change the speed of rotation of the pump rotor, are not widely used in power plants as a drive for feed pumps due to their complexity and unreliability.

In this regard, recently at Russian and foreign power plants, the electric drive of feed pumps with a fluid coupling, which is shown in the Appendix, Fig. P-1,2.

Depending on the required parameters, purpose and operating conditions, a large number of different designs of centrifugal pumps have now been developed, which can be classified according to several criteria. For example, based on the number of impellers, single-stage and multistage pumps are distinguished. In multistage pumps, the pumped liquid passes sequentially through a number of impellers mounted on a common shaft.

The pressure created by such a pump is equal to the sum of the pressures developed by each wheel.

Depending on the number of wheels (stages), pumps can be two-stage, three-stage, etc. In fact, on one shaft there are several single-stage pumps in the form of impellers, which consistently increase the pressure of the entire pump, which is its main pressure-flow characteristic.

Based on the method of supplying water to the impeller, a distinction is made between pumps with one-way supply and pumps with two-way supply or so-called centrifugal pumps with two-way water inlet.

According to the method of draining fluid from the impeller, pumps with volute and turbine outlet are distinguished.

In pumps with a volute outlet, the pumped liquid from the impeller enters directly into the volute chamber and is then either discharged into the pressure pipeline or through transfer channels to the next impellers.

In turbine exhaust pumps, the fluid, before entering the volute chamber, passes through a system of stationary blades that form a special device called a guide vane installed in the pump stator.

Based on the layout of the pump unit (shaft location relative to the supports), horizontal and vertical pumps are distinguished.

According to the method of connection to the engine, centrifugal pumps are divided into drive pumps (with a pulley or gearbox), connected directly to the engines using a coupling, and monoblock pumps, the impeller of which is installed on the elongated end of the electric motor shaft - cantilever pumps.

For example, cantilever type pumps are designated as K-120-15, i.e. console pump, with a capacity of 120 m 3 / hour and a pressure of 15 atm.

The pressure of single-stage centrifugal pumps, commercially produced by Russian industry, reaches 120 m of water. Art. (1.2 MPa; 12 atm).

In turn, serial multistage pumps develop a pressure of up to 2500 m of water. Art. (25 MPa; 250 atm) or more.

The parameters of specially manufactured centrifugal pumps, both single-stage and multi-stage, can be significantly higher.

As for the efficiency, depending on the design, it varies widely - from 0.85 to 0.90 for large single-stage pumps and 0.55-0.60 for high-pressure multistage pumps.

Such low efficiency multistage high-pressure pumps is associated with hydraulic losses in the flow part of the pump and especially with high friction of the unloading steel disk of the hydraulic heel in the axial unloading system of the pump.

In turn, the friction of this monolithic cast iron disk with a thickness of 30-40 mm and a diameter of about 300 mm at a rotation speed of almost 50 rps in a closed water volume (in the hydraulic foot chamber) leads to noticeable heating of the water in the pump, the temperature of which is taken into account in the Rankine thermal cycle .

It is also known that the power consumption of the pump at zero flow, i.e. when the outlet valve is closed (this is idling the pump), it does not drop to zero and is about 30-40% of the rated power of the electric motor. This power is also converted into heat energy, which can increase the temperature of the feed water to the effect of “steaming” the pump, in which the impellers, unloading device, support bearings, pump shaft seals are subjected to mechanical stress and can ultimately lead to emergency failure of the pump. . The increase in feed water temperature ∆t in non-flow mode is determined by the formula:

∆t = 632N (1-h) / 1000Q(o C), (20)

N – electric motor power, kW;

h - efficiency pump;

Q – pump flow, kg/s.

From equation (20) it follows that with a decrease in pump flow Q, the temperature of the feed water increases.

Sometimes this method of increasing the temperature of the feed water is used by machine operators when starting up power units, which, of course, is neither economical nor rational from the point of view of the reliability of the pumping unit. From page 68, it follows that the maximum permissible increase in water temperature reaches 11 o C and is based on the assumption that only the heat caused by hydraulic losses inside the pump contributes to an increase in the temperature of the feed water in the pump by this amount. In fact, the limit for increasing the water temperature in the pump is most often arbitrary. For example, for pumps that do not have unloading devices (recirculation line), sometimes in order to maintain a minimum flow through a slightly open pressure valve, it is allowed to increase the temperature to 30 o C in order to avoid “steaming”.

But in any case, operation of a centrifugal pump, especially a multistage one, in non-flow mode is not permissible for more than three minutes.

At modern large power plants, the power of electric motors driving feed pumps reaches several thousand kilowatts. From here you can imagine how quickly and high the temperature of the feedwater can rise at zero flow, when these thousands of kilowatts of electrical energy are converted into thermal energy.

But be that as it may, centrifugal pumps differ from other pumps in the unique property of self-regulation and the possibility of forced regulation in a wide range of their performance and pressure. Self-regulation means an independent change in operating mode with a change in network resistance, which is especially important for electrically driven feed pumps and the maneuverability of power units. This property of central hydraulic pumps is widely used in the operation of pumps, especially when they are included in parallel operation on a common hydraulic network, both during scheduled switching on and during emergency automatic switching on of the reserve (AVR). In the next section we will look at options for incorporating a feed pumping unit into a power plant circuit.

Chapter 2. Feeding installations of thermal power plants

2.1 Inclusion of the feed pump in the thermal circuit of the power plant

We know that the feed pump forces feed water from the deaerator, increasing its pressure to P p.p. . =(1.25-1.3) P 0, where P 0 is the pressure of live steam in front of the turbine, taking into account the resistance of the feed path and heating surfaces of the steam boiler. Modern power plants use several schemes for switching on feed pumps, but we will consider only two of them, the most used.

1. Single-lift scheme, in which the feed pump supplies water with a final design pressure through the HPH to the feed unit of the steam boiler:

Rice. 13. Single-lift schematic diagram for switching on the feed pump

This scheme is used on power units with a capacity of up to 200 MW.

Advantages of this scheme:

1. relative ease of adjusting the feed water flow rate by the feed pump.

Feature: high pressure heaters (HPH) operate under very high pressure created by the feed pump. Due to the high pressure drop across the HPH, they are subject to high requirements for operational reliability and increased capital costs to ensure it, associated with an increase in the wall thickness of the heat exchanger housing.

2. Double-lift scheme, in which the feed pumps of the first lift pump water through the HPH to the feed pumps of the second lift, which supply water to the steam boiler:

Rice. 14. Schematic diagram of a two-lift feed pump switching on

This scheme can be used on power units with a capacity of 300 MW and above.

Advantages of this scheme:

1. performing the HPH at a lower pressure, determined by the fact that the water pressure at the inlet to the second lift pumps must, in order to prevent cavitation, slightly exceed the saturation pressure at the water temperature in front of the pumps, therefore the requirements for the reliability of the HPH are somewhat lower than in single-lift schemes.

Flaws:

1. reduced reliability of second lift feed pumps pumping water with a high final temperature;

2. increasing complexity and cost of the feeding plant;

3.increased energy consumption for pumping water with a higher temperature;

4. the need to synchronize pumps I and II of lift and the complexity of their regulation, because The second lift feed pump operates on hot water, which will instantly boil when the pressure decreases.

1.2. Feed pump drive

There are two options for feed pump drives:

1) electric;

2) turbine.

Electric drive of feed pumps

Advantages:

1) simplicity of design (synchronous or asynchronous electric motor);

2) high reliability.

Flaws:

1) the unit power of the engine is limited to 9000 kW;

2) limited possibilities for regulating feedwater flow.

Turbine drive of feed pumps

Advantages:

1) the ability to regulate the rotation speed, as well as the water supply in a wide range;

2) compactness;

3) independence from electrical power.

The choice of the PN electric motor is made on the basis of thermal and economic comparison of options.

In this regard, the power of the feed pump is determined by the formula:

, (21)

Q p.v. . – feed water consumption, kg/s;

Water pressure drop in the feed pump, kg/cm 2 ;

Average temperature of feed water at the outlet of the PN, o C;

pump efficiency;

Fluid coupling efficiency (if any).

The condition for thermal efficiency of a turbine or electric drive is the following ratio:

(22)

The efficiency coefficients of energy conversion and transmission with a turbo drive and an electric drive are respectively equal:

(23)

where are the internal relative efficiencies of the main and drive turbines;

I - mechanical efficiency of the main and drive turbines;

Throttling coefficient during steam transport in the drive turbine path;

Generator efficiency;

Efficiency of the electrical transformer and the electrical network for auxiliary needs;

Drive motor efficiency;

Fluid coupling efficiency.

At thermal power plants, an electric drive is usually used, and at condensing power plants (CPS), the type of drive depends on the power of the power units.

For example:

1) for power units with a capacity of 200 MW and less, electric drives are used;

2) for power units with a capacity of 300 MW:

· at Ne<30 % - электроприводы;

· at 30%

In conclusion, I want to say that the feed pump in the circuit of a thermal power plant, be it a classic one using natural fuel or a nuclear power plant using nuclear fuel, is an object of increased monitoring and control and is no less important than a steam turbine or steam boiler (nuclear reactor) and the correctness its operation also affects the trouble-free operation of the power unit and its reliability.

In the next section of the Manual, we will consider the commissioning of an electric feed pump after repair, where we will consider the phased commissioning of both the pump itself and all its auxiliary systems: oil system pumps and oil coolers.

2.2 Putting into operation after repairing the oil system of the electric feed pump

Let's consider the technological diagram of the oil system piping of an electric feed pump (Fig. 15), which can be either autonomous or common to several PEN (electric feed pump).

Fig. 15. Schematic flow diagram of the PEN oil system

1, 2 – oil pumps of the lubrication system;

3, 4 – oil coolers, shell and tube;

MM-1, 2 – pressure gauges, type OBM;

R-1, 2 – valves on the oil pump recirculation line;

EKM-1, 2 – electric contact pressure gauges;

MF-1, 2 – oil filters, two for one oil cooler.

The PEN oil supply system is an autonomous system with its own oil tank, a group of electric pumps (usually two electric pumps, one of which is working, the second is at the ATS or under repair), oil coolers, oil filters, fittings, flanges and pipelines, as well as automatic protection and technological interlocks, and if one working oil pump fails, an emergency signal turns on the backup oil pump located on the automatic transfer switch, whose oil supply system is working, the oil tank with a nominal oil level and the system with oil pumps are ready to be put into operation, the flow of cooling water is configured through the oil cooler, which after switching on PEN and oil pump into operation, the driver will adjust the PEN as the oil temperature rises, preventing it from exceeding the nominal value.

If it is impossible to regulate the oil temperature, urgently connect a backup oil cooler using cooling water, and remove the defective one from operation by closing the oil output valve, thereby placing the oil cooler under pressure testing from the oil pump, and flush it with a reverse flow of cooling water and inform the senior turbine shop operator (SMTC).

The PEN oil system at all thermal and nuclear power plants is largely unified, which simplifies its operation and maintainability, which is especially important for operating personnel.

The PEN oil system works as follows.

Used hot oil with a temperature not exceeding 55 °C from the bearings of the feed pump and its electric motor (two plain bearings each for the pump and electric motor) returns by gravity through the common oil drain line of the pump unit (line “a”) to the PEN oil tank, where it settles and demulsification, the time of which should be no more than 3-5 minutes, otherwise the oil must be sent for cleaning and replaced with fresh oil from the general station oil pipeline coming from the central oil supply of the power plant to the turbine room. To lubricate the bearings of the pump unit, turbine oil is used, as for steam turbines, mainly T-22 or Tp-22, the quality of which must meet the requirements of GOST-32-53-2000.

For reference: (T-22 is Turbine oil (T), with kinematic viscosity ν = 22 centistokes; Tp-22 is Turbine oil (T), with kinematic viscosity ν = 22 centistokes with an additive (p) of a synthetic composition at temperature 20 0 C. Both brands of oils are petroleum cracking distillate. The number after the oil brand - 22, 32 or other brands indicates that the kinematic viscosity of the oil is 22, 32 times higher than the kinematic viscosity of distilled water. The demulsification time indicates the amount of water present in the oil and the longer this time, the more watered the oil is, the lower its kinematic viscosity.Water aggressively affects the babbitt filling of the liner (in the babbitt alloy up to 80% tin) bearings of the pump and PEN electric motor, which leads to corrosive wear of the liner and a decrease in its service life ).

After settling in the oil tank, the oil enters the suction of electric oil pumps (1, 2). Typically, oil pumps are installed with low flow rates (up to 3-5 m 3 /h), but with high pressure - up to 30.0 atm (3.0 MPa). It follows that PEN oil pumps can be of a screw, gear, plunger or other type, which, if started incorrectly (especially in non-flow mode), can lead to damage to both the pressure oil pipeline (rupture of the flange connection of the pipelines) and the pump itself (squeezing out the pump seals , damage to pressure and suction fittings). Then the oil under pressure from the pump (one pump is in operation, the second is in AVR or under repair) through one of the oil filters (MF-1, 2), which is connected to operation, the second is in reserve (repair), enters one of the oil coolers, the other oil cooler is in reserve or repair. Here the oil is cooled with technical water to 40 0 ​​C and with an excess pressure of 0.7-1.2 atm is sent to the common oil supply line, and from it it is distributed to the bearings of the pump and electric motor, while the oil pressure in front of the bearings must not increase above 1.2 atm . When the oil pressure in the pressure pipeline increases to 1.3-1.5 atm, a mechanical safety valve is installed, which releases excess pressure at the end of the oil line into the oil tank. To regulate the amount of oil in front of the bearings, throttle washers are installed in the oil lines, the diameter of which is determined experimentally during test runs of the pump after repair and is entered into the pump’s repair and technical circular.

On NPP feed pumps, in the housing of the pump and electric motor bearings, there is a special volume for oil with ring lubrication, which is designed for emergency run-down of the pump unit and to prevent melting of the Babbitt filling of the bearing liners when the oil pumps are turned off when the power unit’s own needs are lost.

Also, on many PENs, pre-connected screws in the form of a multi-entry auger are widely used, which act as a booster (English - booster, from boost - to raise, increase pressure) and they are installed on the pump shaft before the water enters the first stage of the pump flow path. This makes it possible to partially recover from cavitation.

To prevent the ingress of mechanical impurities that may appear from the flows entering the deaerator body, a protective conical mesh is installed in front of the PEN inlet valve inside the pipeline, on which the pressure difference of the feed water “before” and “after” the mesh is measured. If a pressure drop exceeds 2.0 atm, the mesh is washed without stopping or unloading the pump for recirculation.

Protective screens are mounted in a special insert - a “reel”, which is mounted on flanges in the suction pipeline and can be easily dismantled if necessary.

Now we will start starting the feed pump electric unit, but at the beginning of the operations to start the PEN, we will turn on its oil system, without which neither the pump itself nor its drive can operate.

When the PEN is running, the entire oil system is not taken out for repair; it is taken out for repair only simultaneously with the repair of the entire pump unit, and this is understandable: without a lubrication system, the pump and its electric drive, which have plain bearings with forced lubrication, will not be able to work.

All preparatory and start-up work at the PEP is carried out by the operating personnel of the turbine shop, headed by the senior turbine shop (power unit) machinist (SMTC) on the direct orders of the turbine shop shift supervisor (TSTC) for which:

The permit work order for repair work on the PEN oil system is closed, not covered. Usually, one General Work Order is issued for repair work on the entire pumping unit: the feed pump itself and its oil system, while repair work on the electric motor is performed by the personnel of the power plant’s electrical shop, according to the Separation Sheet between the turbine and electrical shops. If it is necessary to perform any work within the pumping unit, for which a General Work Order has been issued as a whole, the responsible manager of repair work for the General Work Order issues an Interim Work Order for repair work on a unit or section of the unit;

In the Work Completion Log (located at the NSTC workplace), the heads of the electrical shop, the thermal automation and measurement shop (CTAM), and the turbine shop (he makes the last entry in this log) make authorizing entries stating that all repair work on the feed pump unit has been completed, The workshop maintenance personnel have been withdrawn and the pump is ready to be put into operation. This is the main legal document giving the NSTC the right to begin start-up operations at the PEN.

The feed pump operator performs the following work:

checks that repair personnel are completely removed from the repair area of ​​the pump unit;

checks that the instrumentation and equipment are intact, not expired by State verification, sealed, connected via impulse lines to sensors (main valves on the impulse lines are open), shut-off, control and protective valves are intact, pipeline flanges are connected with studs that cannot be turned by hand, pump coupling halves and electric motors are coupled and covered with a protective casing, the PEN oil tank hatches are closed, there is no oil in the tank according to the level glass (checks by opening the lower valve of the level glass);

reports to SMTC that the inspection of the pumping unit has been completed. If there are comments that could lead to an emergency on the pump, they are recorded in the Defects Log, which is located at the NSTC workplace, and startup work is stopped until these defects are eliminated by the repair staff of the workshops. The degree of readiness of the pump for start-up is determined by the NSTC, which is responsible for starting the pump;

After eliminating the defects, proceeds to put the PEN oil supply system into operation, the oil tank was accepted by the chemical shop for cleanliness, which was recorded in the Operational Journal of the NSTC;

orders through SMTC the supply of fresh oil to the PEN oil tank by opening the manual valve M-0 (Fig. 15);

determines by the characteristic noise in the oil tank and by the noise in the breathing valve on the oil tank that oil has entered the oil tank, air is displaced through the breathing valve (the breathing valve is a safety device and is designed to seal the gas volume of a tank with petroleum products and maintain pressure in this volume at within specified limits, as well as to protect against flame penetration into the tank); puts the oil level glass into operation, blows it into the atmosphere by opening the valves at the upper and lower ends of the tube, oil should be poured through the lower end of the tube into a previously placed container (usually a metal bucket), then closes the valve and visually checks the oil for its cleanliness and transparency ( To avoid injury, it is prohibited to use glass containers, use only transparent plastic ones);

opens manual valves N-1,2, closing valve M-O, when the nominal oil level in the oil tank is reached (usually a line corresponding to the nominal oil level in the oil tank is marked with red paint on the glass level tube), begins filling the oil pumps with oil, having previously opened the vents and drains from their housings, preventing oil from air vents from reaching the foundation and adjacent equipment. If oil spills on the floor or other places, remove the oil immediately using dry sand and a clean rag. Oily sand and rags are placed in special metal containers and removed from the workshop;

closes the valve when a continuous stream of oil appears from the air vent, and drainage, oil pumps are considered filled with oil and deaerated;

opens the pressure valves of the oil pumps (N-1,2), using pressure gauges (MM-1,2) and EKM-1 checks that they show the value of the static column of oil in the oil tank (0.08-0.10 atm), i.e. The oil level in the tank is about one meter from its bottom. In general, the scale of any pressure gauge should be selected in such a way that when the pump is operating, the value of its pressure is in the second third of the entire scale;

In the summer, supplies process water to the oil coolers by opening the manual valves (TV-1,3), as well as the vents from the pipe system of the oil coolers, fills the oil coolers with water (control - a continuous stream of water flows from the vent, close the vents), pressurize the oil coolers according to water under service water pressure (control - when the valve for emptying the oil space of the oil cooler is opened, there is no water). In the winter season, do not supply service water to the oil coolers, but when the temperature of the oil and Babbitt bearing shells begins to rise, gradually supply service water, avoiding a sharp decrease in the oil temperature;

opens the service water outlet valves (TV-2, 4) from the oil coolers by 1/3, places the oil coolers under the service water flow;

orders the assembly of electrical circuits for oil pumps;

checks, together with CTAI personnel, protections and interlocks on oil pumps (standard list and purpose of technological protections and interlocks of the feed pump, see Appendix 3);

opens the oil recirculation valves (P-1, 2) 1/2, and closes the suction valves (N-1, 3) of the pumps; close the pressure valves (N-2, 4);

turns on the electric motor of one of the oil pumps, gradually opening the suction valve of the oil pump and its

recirculation, at the local oil pump control panel (local control panel MN), controls the loading of the pump electric motor using an ammeter;

turns off the first started pump, tests the second oil pump in operation, knowing that operating oil pumps for recirculation for more than 30 minutes is unacceptable;

inspects oil pumps during operation for defects;

asks the SMTC which oil pump, according to the workshop schedule, should remain in operation and, when the oil system of the PEN itself is ready, supply oil from the operating oil pump to the supply manifold of the PEN oil pipeline through one of the oil coolers, while gradually closing the recirculation valve, check on the M-3 pressure gauge that the oil pressure at the end of the PEN pressure oil line corresponds to the nominal value, according to the PEN Operating Instructions;

switches the key of the operating oil pump "Operating mode MN" to the "Operation" position at the local control room of the MN, and the key of the backup one to the "Reserve" position, otherwise, when the operating pump is turned off, the backup oil pump will not turn on and the feed pump will be emergency shutdown, which will lead to a violation power unit operation;

records in the Operational Log (daily sheet) of the MPEN about the testing of the PEN oil pumps and the state of its oil facilities, reports this to the SMTC and waits for its further orders, without ceasing to monitor the operation of the PEN oil system.

Chapter 3. Simulation of a situation with emergency shutdown of a working oil pump

3.1 Initial condition of the equipment

An electric feed pump with one of two oil pumps is in operation (the second oil pump is located on the AVR), one of two oil coolers (the second is in reserve or repair). There are no deviations from the nominal parameters. Protections, alarms, interlocks and automation of the PEN pumping unit were put into operation in full, which was recorded in the Operational Log (Daily Report) of the MPEN.

3.2 Possible causes of emergency shutdown of a running oil pump

Disabling the electric motor of a running oil pump due to malfunctions, for example, internal damage, a short circuit in the terminal box (water ingress, break in the grounding bus of the electric motor housing), erroneous shutdown by personnel, a malfunction of the control circuit, overcurrent, etc.

Defects of the pump itself, associated, for example, with jamming of the pump or its bearings, breakage of the impeller, disengagement of the coupling of the pump with the electric motor, activation of technological protections, etc.

3.3 Scenario of the emergency process

When one operating oil pump, for example No. 1, is turned off, the oil pressure at the end of the PEN pressure oil line decreases.

In this regard, the value of the oil pressure in EKM-1, installed at the end of this line, reaches the emergency setting for the operation of the automatic transfer switch. Then, from the block contacts of EKM-1, an electrical signal is sent to the switching circuit of the electric motor of the backup oil pump No. 2, located on the automatic transfer switch, the pump unit is switched on without a time delay, replacing the switched-off oil pump. The entire process of passing the ATS and putting the backup oil pump into operation takes no more than 3.0-4.0 seconds. So, a sharp decrease in oil pressure at the end of the oil pressure line PEN due to its large volume does not occur and there will be no breakdown of the oil wedge in the plain bearings of the pump and electric motor.

When the nominal oil pressure at the end of the PEN oil line is reached and this value is established in EKM-2, the block contacts on EKM-1 and EKM-2 are cocked to the nominal operating position and are again ready to send an electrical signal to turn on the backup pump when the oil pressure drops to pressure line of the PEN oil pipeline.

3.4 Actions of operating personnel when the operating one is turned off and the backup oil pump is turned on via ATS

The PEN operator learns that the oil pump has been turned off by a light and sound alarm (howler) and the light display on the light panel of the local PEN control panel (PEN local control panel) has fallen out.

After passing the ATS and turning on the backup oil pump, the PEN driver inspects the oil pump that turned on and the one that turned off in an emergency, checks the value of the nominal oil pressure according to EKM-2 at the end of the oil line of the oil system of the operating PEN.

In the absence or presence of comments, the MPEN reports the incident to the SMTC and NSTC and records this in the Operational Journal (Daily Report) of the PEN.

If there are obvious defects on a disconnected oil pump, SMTC and NSTC personally inspect the defective oil pump, NSTC makes an entry in the Defects Log and in its Operational Log, and reports this to the head of the turbine shop or his deputy for operation.

3.5 Actions of operating personnel when the operating oil pump is turned off and the backup oil pump does not turn on

The PEN operator learns that the operating oil pump has been turned off by a light and sound alarm (beeper) and the display on the light panel at the local control room of the PEN has fallen out.

The warning signals will not be cleared until the driver acknowledges them with the signal acknowledgment button on the local control panel of the PEN, this proves that the driver has accepted the alarm.

After the operating pump is turned off and the ATS signal does not pass through to the backup oil pump (the oil pump does not turn on), the MPEN must immediately, at the local control panel of the PEN, move the locking key from the “ATS” position to the “Manual control” position and try to turn on the oil pump manually. If the oil pump does not turn on, immediately move the locking key of both oil pumps to the “Repair” position and report the event to the SMTC and NSTC (the locking key position is “Repair”, prohibits the inclusion of the PAN both locally and from the control panel - control room).

The MPEN is obliged to urgently monitor the emergency shutdown of the feed pump; in this case, the electrified valve of the recirculation line to the deaerator must be opened, and the pressure valve PEN must be closed. When closing the pressure valve and not opening the recirculation valve, immediately remove the electric valve drive from the “Automatic” and open it manually, knowing that the PEN cannot operate in flow-free mode for more than three minutes.

Using EKM-1 (on the pressure pipe of the PEN), check the zero value of excess pressure in the pressure line of the stopped PEN, this proves that the check valve of the pump is holding, and there is no reverse rotation of the pump (control from the pump coupling side).

The MPEN is obliged to monitor the normal activation of the backup PEN via the ATS and transfer its interlocking key to the local control panel of the PEN from the “ATS” position to the “Operation” position, and take the remaining PENs in operation under enhanced control.

The MPEN reports to the SMTC and the NSTC about all the work and makes a detailed entry in the Operational Journal (Daily Report) of the PEN and writes a detailed explanatory note addressed to the head of the turbine shop about the failure to pass the ATS on the oil pumps, which is transmitted by the NSTC. He carefully studies it, analyzes it, and when dismantling an emergency situation, explains to the personnel the actions of the MPEN. The NSTC is obliged to hand over the explanatory note to the head of the turbine shop personally for making both administrative and technical decisions.

3.6 Actions of operating personnel in case of fire in the PEN oil system

During the next inspection of the operating pumps, the PEN driver discovered an oil fire in one of them in the oil tank or on the oil line.

MPEN is obliged to immediately notify the NSTC and the main control room about this, and independently begin to extinguish the fire:

stop the burning pump by disconnecting from the power supply using the nearest KSA button (emergency stop button for an operating PEN), of which there should be several and they should be installed in easily accessible places within the pump;

turn on the foam fire extinguishing pump (FPPZhT) with a local key and check that high-expansion foam flows abundantly through the foam generators installed above the oil tank or above the oil line of the PEN, make sure that the source of the fire is localized and there is no open fire.

Typically, fire extinguishing foam pumps (at least three) are installed in a strictly guarded separate building on the territory of the power plant next to the underground foam concentrate storage tank.

Russian power plants use several types of foaming agents, but mainly those with a shelf life of at least 36 months.

Currently, a number of different foaming agents are produced in Russia, for example, PO-6CT, 6TS, 6MT, 6TS (3%), 6TS-V, 6TF-U, which mainly contain aqueous solutions of a mixture of surfactants with stabilizing agents additives. But still, all of them are created on the basis of PO-6 and are designed to extinguish fires of classes “A” and “B”, i.e. exactly for our case.

PO-6 is a biodegradable foaming agent for purpose with increased fire extinguishing ability, prepared on the basis of an aqueous solution of triethanolamine salts of primary alkyl sulfates with stabilizing additives with a pH value of pH = 7.0 - 10.0 and a freezing point not lower than minus three degrees. But the most stable foams are formed on the basis of protein foaming agents, which are obtained from a variety of substances, either entirely consisting of protein or containing it in significant quantities. These proteins are extracted from animal blood, skin, bones, horns, hooves, bristles, feathers, fish scales, oilseed cakes, and milk products.

In the production of such foaming agents, proteins are first hydrolyzed, since the products of their hydrolysis have a much higher foaming ability than the original proteins and proteins. To do this, they are subjected to heat treatment, usually in an alkaline environment. Moreover, hydrolysis is not completed, because The products of the final breakdown of proteins, amino acids, although they are quite strong foaming agents, they produce an unstable, quickly collapsing foam.

All protein foaming agents provide a breeding ground for various types of microorganisms. Therefore, they contain antiseptics - fluorides or phenol. Without them, foaming agents quickly lose their properties, rot and smell bad.

In the production of foaming agent PO-6, animal blood obtained from meat processing plants is first hydrolyzed with caustic soda, then neutralized with ammonium chloride or sulfuric acid. The resulting solution is evaporated to a given concentration. To increase the stability of the foam, iron sulfate is added to the foaming agent.

The multiplicity of the resulting foam coming out of a fire nozzle with a foam generator, for example, the GPS type, is more than 60 times, i.e. from a unit volume of foam concentrate PO-6, 60 volumes of foam are obtained with a stability of about 300 seconds (five minutes) at the source of the fire. This time is enough to localize and block the free access of atmospheric oxygen, i.e. stop burning.

NPPZhT are consumers of reliable power supply and belong to the power plant safety system of the first category, therefore one of them must be driven from a direct current source in case of complete loss of the power plant’s own needs, i.e. under MPA conditions (maximum design basis accident) and depending on power, they are put into operation from reversible electrical converters or from general station batteries;

stop the switched on NPPVT;

MPEN in the Operational Journal (Daily Report) PEN records the event that occurred;

the same actions are performed by MPEN in case of fire on the electric motor or on the pump itself;

It is prohibited to extinguish burning electric motors or electrified fittings that are energized with water without dielectric gloves and a special grounding device on the fire hose.

3.7 Security questions

1. In what cases is AVR of oil pumps used?

2.What is the purpose of oil filters on oil coolers?

3.Why can’t vortex oil pumps be put into operation in flow-free mode?

4. Explain the need for a recirculation line for PEN oil pumps.

5. Compare the quality of the turbine oils used.

6. Explain the need for a system of protections and interlocks on PEN oil pumps?

7. Justify the need for a check valve on pumps.

8.What will result from an emergency shutdown of the working oil pump and failure to turn on the backup oil pump?

9.What actions should the PEN driver take if the electric motor or oil tank of the PEN pumping station catches fire?

10. How does PEN axial shear protection work?

11.Composition of the foaming agent?

12. Purpose of KSA.

Chapter 4. Starting up after repair of the electric feed pump

4.1 Study of the technological scheme

The installation of a centrifugal type feed pump performs the following functions:

Feed water intake from the deaerator accumulator tank;

Increase in excess feed water pressure due to high-speed rotation (centrifugal effect) and stepwise sequential increase in water pressure in the pump casing;

Supply of feed water at such a high pressure that it could overcome the hydraulic resistance of the water-steam path of the steam generator, i.e. more fresh steam pressure from the boiler;

Creation of forced movement of feed water in the heating surfaces of the boiler.

We already know that the increase in feedwater pressure is created by the centrifugal effect created by the pump's disc impeller with peripheral blades.

For example, if the pressure at the pump suction is Pvs. = 8.0 atm, and at the pressure should be Pnap. = 158.0 atm (steam pressure is 130 atm), i.e. pressure increase range is: Pnap. - Rvs. = 158.0 -8.0 = 150.0 atm, then with a single-stage pump the diameter of the impeller will be meters, which is unacceptable in terms of reliability and technologically impossible.

Let in our case five pressure increasing stages be installed on the PEN rotor, each of which includes an impeller and its guide vane with axial and radial seals, then each stage sequentially increases the working water pressure by 30.0 atm. and at the pump outlet this value will reach 158.0 atm. (5 stages x 30.0 atm. + 8.0 atm. at suction = 158.0 atm. at pressure).

In high-pressure pumps and with one-way water inlet, axial hydraulic pressure arises during operation, which tends to move the pump rotor (shaft with impellers mounted on it) in the direction opposite to the direction of movement of the water entering the wheel, i.e. towards the pump suction side. Therefore, to compensate for the axial shear force of the pump rotor, an axial unloading system is installed in its flow part, which is described in more detail in Appendix P-5.6.

Now let's look at the basic technological diagram of the electric feed pump, shown in Fig. 16.

Fig. 16. Schematic diagram of the electric feed pump

1 – Electric valve on the suction of the pump from the deaerator (B-1); 2 – Electric valve on the pump pressure (N-1); 3 – Check valve, mechanical (OK); 4 – Manually operated valve on the recirculation line to the deaerator (VR-1); 5 – Electrified valve on the recirculation line to the deaerator (VR-2); 6 – coupling; A – electric contact pressure gauge (EKM-1); B - electric contact pressure gauge (EKM-2);

The electrically driven feed pump includes:

1.feed centrifugal pump (usually multi-stage), installed on a special metal frame, cast and secured with fixed anchor bolts on a special platform of the positive or negative level of the turbine room of the main building of the power plant. The flow part of the pump consists of two casings - an inner and an outer casing. The inner casing consists of cylindrical sections connected in series, each of which contains a working stage with one impeller and a guide vane, axial and radial seals. With its cast feet, each section rests on the horizontal frame of the outer body, and all sections are pulled together by horizontal through pins, thereby creating a single package of cylindrical sections. For example, a five-stage feed pump has five such cylindrical sections;

2. suction and pressure flanged pipes of the pump pipelines with shut-off valves and a mechanical check valve in front of the pump pressure valve. The valve drives are electrified;

3. pipeline of the feed water recirculation line with shut-off valves - two along the valve, the first with a manual drive, and the second valve is electrified;

4. asynchronous type electric motor. The pump electric motor has built-in air coolers, which in turn are cooled by process water supplied from a common manifold in the machine room of the main building of the power plant;

5. coupling, consisting of two coupling halves mounted on the shaft of the pump and the electric motor.

Currently, a hydraulic coupling is widely used, which makes it possible to change the amount of rotation of the entire shaft line of the pump unit, thereby making it possible to regulate the consumed electrical power and the supply of feed water to the steam boiler depending on the electrical load of the power unit, which is impossible to do with an asynchronous drive of the PEN (details about the fluid coupling Appendix Fig. P-1,2);

6. oil supply station for the pumping unit, located under the feed pump level in the basement with its own fire extinguishing system;

7. automatic water and foam fire extinguishing system of the pump unit;

8. station of the oil purification system (mainly oil purification methods are used - purification (cleaning from water) and clarification (cleaning from mechanical impurities)) for all steam pumps of one power unit.

4.2 Putting the PEN into operation after repair

All preparatory and start-up work at the PEP is carried out by the operating personnel of the turbine shop, headed by the senior workshop (power unit) operator (SMTC) on the direct orders of the turbine shop shift supervisor (NSTC).

The permit work order for repair work on the PEN oil system is closed, not covered. Usually, one General work permit is opened for repair work on the entire pump unit (the feed pump itself and its oil system, while repair work on the electric motor is performed by the personnel of the power plant’s electrical shop, according to the “Separation sheet between the turbine and electrical workshops”). If it is necessary to perform any work within the pumping unit, for which a General Work Order has been issued, an Interim Work Order is issued by the responsible manager of repair work for the General Work Order;

In the Work Completion Log (located at the NSTC workplace), the heads of the electrical shop, the thermal automation and measurement shop, and the turbine shop (he makes the last entry in this log) made an authorization entry stating that all repair work on the feed pump unit has been completed, the repair personnel have been withdrawn , the pump is ready to start up. This is the main legal document giving the NSTC the right to begin start-up operations on the PEN after repairs.

The NSTC gives an oral command to the SMTC to begin start-up work on the PEN, which, in turn, gives an order to the PEN driver (MPEN).

4.3 MPEN performs the following work

checks that repair personnel have been removed from the repair area;

removes and carries warning and prohibition posters, chains from fittings and locks to the NSTC workplace;

checks that the instrumentation and equipment are intact, not expired by State verification, sealed, connected via impulse lines to their sensors, shut-off, control and protective valves are intact, pipeline flanges are connected with studs, the coupling halves of the pump and electric motor are engaged and covered with a protective casing;

includes the oil supply station PEN (see paragraphs 2.2. -2.3. of this Manual);

supplies process water to the air coolers of the electric motor by opening the vents and drains, preventing water from entering the electric motor housing; when a continuous stream of water appears from the vents, close them immediately;

opens the suction valve B-1 (Fig. 10) by 10-15% of the manual drive and into the open air vent and drainage from the pump body, checks that water is flowing from the deaerator.

Attention! This work must be done very carefully, avoiding contact of hot water with the human body and nearby equipment.

After deaerating and flushing the pump through the drainage line, close the vent, start heating the metal of the feed pump with the feed water of the deaerator through the open drain of the pump, if the deaerator is under nominal parameters, perform the warm-up at the speed specified in the PEN operating instructions, avoiding water hammer in the pump body up to the complete closure of the suction valve B-1 when water hammer occurs;

after the water hammer stops, slowly open the suction valve B-1 and continue warming up the pump;

order from CTAI the assembly of electrical circuits for the drives of the suction V-1, pressure N-1 valves and recirculation valve VR-2 into the operating position, for remote control of them from the local and block control panel (MCR);

using EKM-1, check that the check valve OK has opened (the pressure gauge should show the excess pressure in the deaerator body plus the height of the feed water column, equal to the difference in elevations between the deaerator installation and the PEN);

fully open the manual recirculation valve VR-1;

when the temperature difference between the pump metal and the feed water in the deaerator reaches no more than ∆t ≤ 50 0 C, fully open the suction valve B-1 from the electric drive;

open the bypass valves of the pressure valve N-1 (not shown in the diagram in Fig. 16) to warm up the pump and equalize the water pressure before and after the pressure valve so that it can be easily opened by an electric drive;

order the assembly of the electrical circuit of the electric motor into a test position in the electrical shop and order a check of technological protections and interlocks on the PEN and the electric motor at the CTAI. The inspection is carried out by the operational personnel of the turbine shop (MPEN) and the operational personnel of the CTAI jointly. It is imperative to check the operation of the emergency button (ESA) to stop the pump by manual testing on site and from the control room;

after checking the protections and interlocks of the PEN and the electric motor, order the assembly of the electrical circuit of the electric motor into the operating position at the electrical shop;

after assembling the electrical circuit of the electric motor into the operating position, the SMTC warns the operating personnel of the main control room about the start-up of the heating element, and turn it on to work with the main control room;

MPEN and SMTC locally control the full opening of the second downstream recirculation valve VR-2, and in the control room the unit operator controls the current load of the electric motor, which should be no more than 30% of the rated value, i.e. I pen ≤ 0.3 I nom;

MPEN and SMTC inspect the entire pumping unit for fistulas and water leaks, vibration, instrumentation and instrumentation readings, noise, and the axial position of the electric motor-pump shafting. If necessary, emergency stop the pump by pressing KSA;

provided that there are no comments on the operation of the pump, give the command to open the pressure valve N-1, while checking that the recirculation valve VR-2 from blocking from the limit switches of the valve N-1 begins to close.

Using EKM-1, we determine that the pressure at the pump head is 5-10% higher than the pressure in the network, i.e. the pump will easily and smoothly enter into parallel operation with other already operating PENs and overcome the resistance of the network;

It is unacceptable to work on recirculation for a long time for strength and thermal reasons PEN;

by the characteristic noise it can be determined that the VR-2 valve has closed and the pump has taken on the full current load, the flow meter shows the nominal flow rate of feed water;

when the air temperature in the air coolers of the electric motor and oil behind the oil coolers MN PEN increases, adjust their values ​​by increasing the flow rate of process water using outlet valves;

set the position of the PEN operating mode key on the local control room and main control room to the "Operation" position;

The MPEN makes a record of the commissioning of the PEN in the Operational Log (Daily Statement), and the driver of the power unit and the NSTC makes a record in his Operational Logs;

The PEN is considered to be put into operation after repair if it has worked without any problems with nominal parameters continuously for at least 72 hours (three days);

According to the workshop schedule, the PEN should not operate continuously for more than 30 days, therefore it is necessary to carry out a planned transition to the reserve PEN. To create equal operating conditions for all PEN of the power unit, the frequency of putting operating pumps into reserve is determined, which ensures the same operating time of the pumps and uniform wear, and also checks the reliability of each pump in long-term operation. But in any case, backup PEPs must be in good working order and in constant readiness for start-up, therefore, the valves on the inlet and outlet pipelines must be open, checks of the ATS must be carried out periodically on a schedule at least once a calendar month, major repairs of the PEP must be carried out at least once every three to four years.

4.4 Security questions

1. What functions does the feed pump perform in the power unit circuit?

2. What physical effect is the method of increasing fluid pressure in the feed pump based on?

3. Why does the temperature of the feed water in the PEN increase?

4. What determines the quality of feedwater deaeration?

5. How is the axial displacement of the PEN rotor compensated?

6. Describe the main stages of commissioning the PEN?

7. What devices are provided to prevent reverse rotation of the pump?

8. Justify the need for a PEN recycling line?

9. What is the purpose of the ECM on the PEN?

10. Why is the appearance of fistulas on PEN dangerous for personnel?

11. What schemes exist for switching on the PEN at the power unit?

12. What unloading devices are available on the PEN when it is put into operation?

Chapter 5. Joint operation of two or more feed pumps on a common hydraulic network

In this chapter we will consider options for the joint operation of centrifugal feed pumps, both in series and in parallel connection to a common hydraulic network.

Typically, pumps are included in parallel operation, on which the service life, reliability, efficiency and safety of the operating power unit depend. Such pumps include feedwater, condensate, circulation pumps, pumps for lubrication systems of turbines, generators, firefighting and other pumps.

To simplify the design of a power plant during parallel operation, pumps of the same type are usually used, which makes it possible to expand the range of regulation of water supply to the network.

The need for sequential operation of pumps arises mainly to provide favorable suction conditions to a more powerful pump at the expense of a less powerful one. For example, the use of boosters and pre-switched pumps can significantly reduce the weight and size of the main feed pump. The need to turn on pumps in series may also arise when one pump of the network in question fails to create sufficient pressure.

5.1 Parallel operation of centrifugal pumps

Pumps in pumping stations and large pumping installations usually work together, i.e. Multiple pumps supply fluid to one hydraulic system. In this case, the pumps can be connected to the system in series (sequential operation) or in parallel (parallel operation). Parallel is the joint and simultaneous operation of several pumps connected by pressure pipes to a common hydraulic system. To avoid the surge phenomenon, it is best not to use pumps whose pressure characteristics have ascending sections when connected in parallel. These include pumps whose impellers have a speed coefficient of 500 ≥ n s ≥ 80.

5.2 Parallel operation of centrifugal pumps with the same characteristics

In Fig. 17(a) shows the flow-pressure characteristic Q - H of each of two identical pumps. In order to construct the total characteristic of these two pumps during parallel operation, it is necessary to double the abscissa of the Q-H curve of one pump at the same ordinates (pressures). For example, to find a point in the total characteristic Q - H, it is necessary to double the segment (ab). Thus, the segment (ab = 2ab). Other points of the summary characteristic are also found.

Rice. 17. Characteristics of parallel operation of two centrifugal pumps in one system a). pumps with the same characteristics; b). pumps with different characteristics

To determine the mode of joint operation of pumps, the P - E characteristic of the system must be constructed in the same way as when one pump is operating. The operating point in this case will be at the intersection of the total characteristics of the pumps and the characteristics of the system.

The total flow during parallel operation of two pumps is characterized by the abscissa of point 2 and is equal to Q I + I 1, the pressure corresponds to the ordinate of point 2, equal to H I + I 1 or Hi.

To establish in which mode each pump operates, it is necessary to draw a line from point 2 parallel to the abscissa axis. The abscissa corresponding to the point of intersection of this line with the Q - H curve of the pump (point 1) will determine the flow rate, and the ordinate - the pressure H i of each of the parallel operating pumps.

Consequently, the pressure developed by each pump is equal to the pressure developed by two pumps when they operate in parallel, and the flow of each pump is equal to half the total flow of the two pumps.

If only one pump supplied liquid to this system, then its operating mode would be characterized by pressure and flow at point 5.

As can be seen from Fig. 17(a) in this case its supply Q 0 would be greater than in the case of parallel operation with the second pump.

Thus, the total flow of pumps operating in parallel in a common system is less than the sum of the flow of the same pumps when operating separately. This is due to the fact that with an increase in the total flow rate of liquid supplied to the system, the pressure loss increases, and therefore the pressure required to supply this flow rate also increases, which entails a decrease in the flow rate of each pump.

The efficiency of each of the parallel operating pumps is characterized by its efficiency at point 4 at the intersection of the Q - η curve with the perpendicular dropped from point 1. As can be seen from Fig. 17(a), the efficiency of each of the pumps operating in parallel also differs from the efficiency of the pump when operating separately, which is characterized by the efficiency at point 3 on the Q - η curve.

The power of each of the parallel operating pumps is characterized by the power at point 7 on the Q-N curve, while the power of a separately operating pump is determined by the power at point 6. When constructing the total characteristic of three parallel operating pumps, it is necessary to triple the abscissa of the characteristic of each pump. The operating mode of three or more pumps when they are connected in parallel is determined in the same way as in the case of parallel operation of two pumps.

When the number of pumps operating in parallel increases or when the resistance of the system increases, for example, when one of the sections of parallel operating water pipelines is turned off during an accident, the flow of each pump individually decreases.

Parallel operation of identical pumps in one system is effective for flat system characteristics and steep pump characteristics. With a steep system characteristic, parallel operation may be ineffective, since when a second or third pump is connected to one pump, the flow will increase slightly.

Identical pumps for parallel operation according to catalogs should be selected so that the optimal characteristic point corresponds to the pressure calculated to supply the entire flow rate to the system, and a supply equal to the total flow rate divided by the number of identical pumps turned on.

When two pumps operate in parallel, their total performance is less than twice the performance of one pump. Typically, when one pump is running, the flow is 60% of the total flow when two pumps are running in parallel.

The slope of the network characteristic curve is determined by the pressure loss to overcome resistance in the pipeline.

It is known that the amount of losses is inversely proportional to the pipeline diameter to the fifth power (∆h ≡ 1/ D 5 pipes) or with a large pipeline diameter, lower pump pressures are required to pass the same flow rates, and the network characteristic will be flat. Therefore, pressure and discharge conduits for circulating water at power plants are made of large-diameter pipes. With a small pipeline diameter, large pump pressures are required, and the network characteristic will be steep.

You can adjust the new pump to a given flow rate Qnew, but with less pressure, with a slight decrease in efficiency. – by turning the impellers, if there is no spare impeller with a smaller diameter.

When operating pumping equipment at power plants, it is often necessary to change the pressure and flow characteristics of an existing pump without purchasing a new pump. In this regard, it is necessary to trim the impellers of the existing pump.

But in order to avoid a significant decrease in efficiency. pump, the reduction in the diameter of the impellers of a centrifugal pump is limited to the following limits (Table 1):

At ns > 350, turning of the impellers is usually not performed.

With an accuracy of 2-5% sufficient for practical purposes, the reduction in the diameter of the impeller is determined using a parabola of proportionality, constructed according to the formula:

H = Hnew Q 2 old /Q 2 new = BQ 2 old. (25)

In this case, the value of the new diameter Dnew. determined by the formula:

Dnew = Qnew / Qstar. (26)

Dnew = Dstar. ÖHnew / Hstar. (27)

ns = (365nÖQ) / Н 3/4 ,(28)

where Q is pump flow, m 3 /sec;

N – pump pressure, m.w.c.;

n – pump speed, rpm.

Usually if:

ns ≤ 60 - these are low-speed centrifugal pumps;

ns ≤ 70-150 are normal centrifugal pumps;

ns = 150 – 360 - these are high-speed centrifugal pumps with maximum efficiency;

ns = 350 – 650 – these are diagonal pumps;

ns = 600 – 1200 are axial pumps with high flow.

When determining ns for double-suction pumps, their performance is divided by 2, and for multistage pumps, the pressure is divided by the number of impellers.

5.3 Parallel operation of centrifugal pumps with different characteristics

Pumps with different characteristics can only operate in parallel under certain conditions, depending on the relationship between the characteristics of these pumps. It is possible to analyze the possibility and feasibility of parallel operation of pumps with different characteristics by combining the characteristics of the pumps and the system. Figure 17(b) shows the characteristics of pumps I and II. As can be seen from the figure, pump II develops less pressure than pump I. Therefore, pump II can operate in parallel with pump I, only starting from the point where the pressures they develop are equal (point C in Fig. 17(b)). The characteristic of the joint operation of pumps (total characteristic), starting from point C, is constructed by adding the abscissas of the characteristics of pumps I and II at the same ordinates (pressures developed by the pumps). To determine the total flow, it is necessary to construct a characteristic of the system (PE curve Fig. 17 (b). Then, from point A - the point of intersection of the system characteristic with the total characteristic of the joint operation of pumps I and II, a line should be drawn parallel to the ordinate axis, which will cut off a segment on the abscissa axis , corresponding to the flow rate Q i + i 1 supplied to the system by both pumps. The supply of each of the jointly operating pumps can be found by drawing a straight line from point A, parallel to the abscissa axis. The intersection of this straight line with the characteristics of pumps I and II gives the corresponding points 1 "and 2 "feed rates Q" i

As in the case of parallel operation of two pumps with the same characteristics, the total flow of the two pumps is less than the sum of the flows of each pump individually. From Fig. 17(b) it is clear that Q I +Q I >Q I + II.

The power and efficiency of jointly operating pumps are determined in the same way as in the case of joint parallel operation of two pumps with the same characteristics. The principle of constructing the characteristics of the parallel operation of different pumps is also used to construct the characteristics of the parallel operation of several identical pumps, when the flow of one of them is controlled by changing the rotation speed.

5.4 Inclusion of two electric feed pumps in parallel operation

Now we will consider the option of including a PEN in parallel operation while another PEN is running, and what conditions must be met for this. The first and most necessary condition is that the pressure of the pump being switched on exceeds the operating pressure in the network by at least 10-15%. Otherwise, the pump will not be able to enter the network, but will operate idling in a non-flow mode, which is equivalent to a closed pressure valve. We already know what this can lead to, and that this mode of operation of a centrifugal pump will not be allowed for more than three minutes.

Figure 18 shows a diagram for connecting two feed pumps in parallel operation, while they have the same pressure-flow characteristics, are of the same type, and both are in good working order. Typically, with this scheme of connecting pumps to a common hydraulic network, one of them is in operation, and the other is in ATS or under repair. Let's consider the following version of the state of the original circuit in Fig. 18: PEN-1 is in operation, and PEN-2 must be put into operation after repair. The work is performed by the operating personnel of the turbine shop - the senior workshop operator (SMTC) and the feed pump operator (MPN).

Rice. 18. Scheme for connecting two feed pumps to parallel operation

PEN-1,2 – feed pumps;

VZ-1,2 – suction valves of feed pumps;

OK-1,2 – check valves of feed pumps;

NZ-1,2 – pressure valves of feed pumps;

VR-1,2 – recirculation valves;

VB-1,2 – bypass valve of the pressure valve.

EKM-1,2,3 – electric contact pressure gauges.

In the Thermal Automation and Measurement Shop (TsTAI), order the assembly of electrical circuits for the drive of the suction (VZ-2), pressure (NZ-2) valves and recirculation valve (VR-2);

Put the PEN-2 oil supply system into operation;

Slowly opening the VZ-2 suction valve, fill the pump with hot feed water from the deaerator, knowing that its temperature is about 160 o C, gradually warm up the pump, avoiding water hammer, and control the heating according to the readings of thermometers on the local pump control panel;

Through bypass VB-2 of the pressure valve NZ-2, fill and warm up a section of the pressure pipeline from the general network pipeline and thereby relieve the pressure valve valve from one-sided pressure from the discharge side of the pump. If this unloading is not performed, then the NZ-2 pressure valve will be difficult to open using an electric drive, which will “sit on the coupling”, which will lead to knockout of the drive electrical circuit due to current overload and a delay in starting the pump, and even failure of the electric drive of the NZ valve -2;

Using EKM-2, determine that PEN-2 is filled with water and heated up (we determine the metal temperature of the pump using the readings of the measuring device on the local PEN-2 control panel, which is located next to the pump).

It is forbidden to open the vents to warm up the pump; it is allowed to open the drainage valve from the pump body, and after warming up, close it;

Turn the pressure valve NZ-2 and the recirculation valve VR-2 from the electric drive;

Through the shift supervisor of the electrical department, order the assembly of the PEN-2 electrical circuit into a test position;

Together with the CTAI staff, check the operation of technological protections and interlocks at PEN-2;

Through the shift supervisor of the electrical department, order the assembly of the electrical circuit for switching the PEN-2 electric motor into the operating position;

Check that the suction valve VZ-2 is fully open, the pressure valve is closed, but the electrical circuit of its drive is assembled, the manual valve on the recirculation line is open, and the electric valve is closed, but its electric drive circuit is assembled, the drainage and vents of the pump are closed, the bypass of the pressure valve NC -2 closed;

Turn on the PEN-2 electric motor, we see from the ammeter on the local PEN-2 panel that its arrow is on the red line, which indicates that the pump is operating at closed pressure, we will check the automatic opening of the recirculation valve from the electric drive, using the ECM-2 we check that the pressure created by PEN-2 is higher than the pressure in the network according to EKM-3. This indicates that PEN-2 will overcome the network resistance and will freely enter into parallel operation with the PEN-1 pump;

After three minutes, the pressure valve NZ-2 should automatically open, and the recirculation valve VR-2 should start closing. If this valve operation scheme does not operate, the MPEN is obliged to manually open the pressure valve from the local control panel PEN-2. In this case, switch the interlock key from “Automatic” to “Local” control and also manually close the recirculation valve – VR-2;

Using the ammeter on the local PEN-2 control panel, check that the electric motor has taken up the current load, the instrument needle has “fallen off” from the red line to the lower side and settled at the value of the nominal value of the operating current of the electric motor;

For another 20-30 minutes, it is necessary to monitor the operation of the PEN-2 pumping unit, paying special attention to the current load, the temperature of the pump metal, the operation of the PEN-2 oil system, the axial shift, so that all readings of standard instrumentation are within the operating limits.

The MPN records in the daily sheet the time when PEN-2 was put into operation and reports on the work performed by the SMTC.

5.5 Security questions

1. In what operational documentation are technological operations performed on the equipment?

2. What does it mean to “sit on the clutch”?

3. Purpose of the bypass line of the PEN pressure valve?

4. Purpose of ECM for PEN?

5. What is water hammer?

6. How can you avoid water hammer in the pump?

7. Purpose of the deaerator?

8. Why are pre-connected screws and augers needed?

9. Purpose and operation of the check valve on the PEN?

10. Necessary conditions for the pump to enter parallel operation?

11. Why and when is the pump impeller trimmed?

12. How can you determine the total productivity of two pumps operating in parallel?

APPLICATIONS

An authorization work order (work order) is a task for the performance of work, drawn up on a special form of the established form and defining the content, place of work, time of its start and end, conditions for safe conduct, composition of the team and persons responsible for the safe performance of the work.

At nuclear power plants, a dosimetry permit is issued. A dosimetry permit is a written assignment for the safe performance of work. The work permit specifies the content of the work, the place and time of its implementation, the necessary safety measures and the composition of the team. When performing work according to dosimetric permits, responsible persons are appointed for the safe performance of work.

The person issuing the permit is responsible for the possibility of safe work and the completeness of the prescribed radiation safety measures. Safety measures are determined based on the results of measuring the radiation situation and are recorded in the column “Conditions of work”, and in the column “Additional personal protective equipment” the required PPE sets are indicated. The work performer is responsible for acceptance of the workplace in accordance with the requirements of the permit, and compliance with radiation safety measures personally and by team members, for decontamination of the workplace after completing the task to acceptable levels.

The permitter is responsible for the full implementation of radiation safety measures in accordance with the work permit, the correct admission to work and the acceptance of the workplace upon completion of work. The dosimetrist is responsible for the correct measurement of the parameters of the radiation situation before the admission of the team and during its work, periodic monitoring of compliance with radiation safety measures by those working during the work.

Team members are responsible for compliance with radiation safety measures and the correct use of personal protective equipment provided for in the work permit.

The order is also a task for the safe performance of work. It is formalized by an entry in the journal for registering work permits and orders and is of a one-time nature. The duration of the order is determined by the length of the team’s working day. The list of work performed according to work permits or orders is approved by the management of the power plant.

PERMISSION WORK FORM

Enterprise _________ Division __________

OUTFIT, GENERAL OUTFIT, INTERMEDIATE OUTFIT N ____

_________________________________________

TO THE GENERAL OUTFIT N ______

(to be completed only when an interim order is issued)

To the work manager ___________________________________

For the work manager (supervisor)_________________

(cross out what is unnecessary) (surname, initials, position, rank)

with team members _____ people. __________________________

(last name, initials, rank, group)

Guaranteed _____________________________________

________________________________________________

Start of work: date ____________, time ____________

End: date _________, time __________

To ensure a safe environment it is necessary to ____________________

(the necessary measures for preparing workplaces and safety measures are listed, including those to be carried out by the duty personnel of other workshops)

Special conditions ______________________________________

The work order was issued: date ________, time ________, position

The work was extended by: date ______, time _______, position

Signature __________________, surname, initials

date Time ______________________

The conditions for the work have been fulfilled: date _______, time

Remain in work ______________________________

(equipment located near the place of work and under voltage, pressure, high temperature, explosive, etc.)

On-duty personnel of other workshops (areas) _____________

(shop, position, signature, surname, initials)

Note on the permission of the power plant shift supervisor (duty dispatcher)___________________________

(signature or note about permission given over the phone, signature of the workshop shift supervisor)

Responsible person for the duty personnel of the workshop (unit, district);

supervisor of work on intermediate work (cross out what is not necessary) ______________________________

Compliance with the conditions for the work was checked, the equipment remaining in operation was familiarized with and allowed to work.

Date Time ______________

Performance Manager ____________________________________

Work producer _____________________

Registration of daily access to work, completion of work, transfer to another workplace. The work is completely finished, the team has been removed, grounding,

installed by the team, removed, reported to (to) ___________________

Date Time______________

Producer of works

(observer) ______________________

Responsible work manager ____________________

Standard technological protections and interlocks on PEN.

Let's consider existing protections, interlocks and alarms using the example of an electric feed pump of the SPE-1250-75 type, used in both thermal and nuclear power plants.

Currently, other types of PEN are used, but the principle of constructing protections and interlocks with signaling deviations in the operating parameters of the pumping unit remains the same: to ensure maximum safe operation of the pumping unit - feed pump-electric motor

Thermal protection:

Decrease in feed water pressure at pump head to less than 40 atm. – activation comes from the ECM installed at the local control room. When the pump starts, the protection pad is automatically disabled for 30 seconds.

Increase in pressure in the axial unloading chamber of the pump by more than 12 atm. – the protection is triggered by the ECM installed at the local control room.

Reduced oil pressure at the end of the oil line is less than 35 atm. – the operation comes from the ECM installed at the local control room, the delay time of the protection operation is 8 seconds.

Electrical protection:

Differential protection of the electric motor against inter-phase short circuit - without a time delay, it acts to disconnect the oil switch of the pump motor;

Minimum voltage protection when the supply voltage drops when:

Umin = 0.65 Unom., the oil switch is turned off with a time delay of 35 seconds;

Umin = 0.45 Unom., the oil switch is turned off with a time delay of 7.0 seconds;

Protection of the electric motor from current overload when the overload current Iac is reached. = 1.5Inom. The protection operates with a time delay greater than the duration of the starting current.

Protection of the electric motor from a short circuit of the stator winding to ground - only a warning signal is sent to the local control board of the PEN.

PEN blocking:

The pump is switched on until:

Increasing the oil pressure in the lubrication system to more than 0.5 atm and opening the feed water recirculation line to the deaerator;

When the feedwater flow rate decreases to less than 400 m 3 /hour, the recirculation valves from the VMD to the local control room of the PEN are opened;

When the feedwater flow rate is more than 480 m 3 /hour, the recirculation line to the deaerator is closed;

AVR of PEN oil pumps occurs:

Upon shutdown of a running pump;

When the pressure at the oil pump pressure drops to less than 1.8 atm. – the signal comes from the ECM installed at the local control room;

When the lubricant pressure decreases to 0.5 atm. - the backup oil pump is turned on;

When the lubricant pressure decreases to 0.35 atm. – PEN turns off.

Signaling deviations during normal operation of the PEN.

Decrease in feed water pressure at pump head to less than 82 atm. a flashing sign appears on the pump mimic diagram in the control room;

A decrease in the oil level in the PEN oil tank is less than 0.1 m from the nominal level - the warning blinker at the local control panel of the PEN falls out, and a sound signal sounds;

An increase in the oil temperature at the inlet to the bearings of the pump unit exceeds 45 °C – the warning blinker falls out on the local control panel of the PEN, and an audible signal sounds;

An increase in the temperature of the oil at the drain from the bearings of the pump unit exceeds 70 ° C - the warning blinker falls out on the local control panel of the PEN, and a sound signal sounds.

PEN with fluid coupling.

In Fig. P-1 shows a PEN, where a hydraulic coupling (fluid coupling), widely used in modern power plants, is shown as a connecting coupling.

Rice. P-1 General view of the feed pump assembly

Rice. P-2. Pumping unit PEN with hydraulic coupling

A – block of the automatic control system (ACS) and oil supply to the fluid coupling.

Rice. P-3. Hydraulic coupling

Rice. P-4. Energy savings from using a fluid coupling

From the analysis of the graphs in Fig. P-4 follows that with small feeds of the PEN, maximum energy savings are achieved on its drive from an asynchronous electric motor, which cannot be achieved with rigid couplings. This is especially important when the power unit is often unloaded up to a complete shutdown according to the operating or dispatch schedule, or when the power unit is involved in regulating the power of the power system, usually at night. This ability to regulate power and supply of PEN is also important during startups and shutdowns of the power unit, which provides significant savings in electricity for the power plant’s own needs.

PEN axial unloading system.

In pumps with one-way water inlet, axial hydraulic pressure arises during operation, which tends to move the pump rotor (shaft with impellers mounted on it) in the direction opposite to the direction of movement of water entering the wheel.

How can you balance the axial force? This can be achieved:

1. two-way water inlet into the impeller, and in a multistage pump - the corresponding group arrangement of impellers on the pump shaft (mixed type);

2. by drilling holes in the rear wall of the impeller, through which there is a slight reduction in the difference in forces acting on the outer and inner walls of the impeller; in this case, the wheel has seals on both sides, however, these drillings reduce efficiency. stages and in modern pumps this method of axial unloading is almost never used;

3. the device of a hydraulic heel for multi-stage pumps.

Due to the fact that the first two methods are not used in the design of feed pumps, we will consider only the third method of balancing the axial force - this is the device of a hydraulic heel for multi-stage feed pumps.

How the PEN hydraulic heel works.

The hydraulic foot is a massive disk mounted on the pump shaft behind its last stage. In Fig. P -5 shows the operating diagram of the hydraulic heel: water from the pump inlet chamber (A), passing through the annular gap (3) and the radial gap (B), enters the hydraulic heel chamber (4), from which it exits into the chamber connected to the atmosphere or with pump suction pipe.

Rice. P-5. Schematic diagram of axial unloading of a feed pump

1 - The last pump impeller along the feed water flow;

2 - Hydraulic washer;

3 - Annular gap;

4 - Hydraulic chamber;

5 - Hydraulic disc;

6 - Hydraulic seal of the pump shaft;

A – Feed water inlet from the impeller;

B – Radial clearance (during pump operation – no more than 0.15-0.20 mm);

B - Dynamic force displacement of the pump rotor towards the pressure;

D – Force of hydraulic unloading of the pump rotor towards the suction side.

The axial force in modern feed pumps is directed towards the pump suction and amounts to several tons. Therefore, the axial force is unloaded using a hydraulic foot (unloading disk), the operation of which is shown in the Appendix in Fig. P-6, where it is shown that for axial unloading of the pump, vector A of the axial displacement of the pump rotor is directed towards its suction (pressure pressure is 16 times greater than the water pressure at the suction - vector B, P 2 = 8 atm), on the shaft with On the pressure side, a unloading monolithic disk is installed, into the chamber of which feed water is supplied from the pump pressure in the opposite direction of the displacement vector.

Rice. P-6. Diagram of the unloading chamber and the forces acting on the unloading disk

Feed pump malfunctions

Mechanical damage and malfunctions of feed pumps occur due to:

Unsatisfactory repairs and maintenance;

Incorrect assembly, alignment and drive, balancing during installation, poor lubrication of bearings;

Errors when starting and stopping.

The following can lead to serious consequences:

Absence or improper design and use of feed pump unloading lines;

Absence or malfunction of check valves and flow limiters on the unloading lines, their inclusion in the common unloading pipeline and in the suction line of the feed pumps.

Malfunctions in the operation of feed pumps that can lead to an emergency stop of the boiler, their causes and methods of elimination are given in the passports and technical descriptions of the pumps.

To ensure reliable operation of feed pumps, the manufacturer guarantees their proper operation, taking into account the use of spare parts, for at least 12 months. from the date of commissioning for condensate pumps with a flow rate of up to 20 m3 / h and at least 24 months. for all other pumps, subject to compliance with the rules of transportation, storage, installation and operation.

Preservation of pumps and spare parts is carried out in such a way as to ensure their protection against corrosion during transportation and storage without re-preservation for two years. In addition, all openings, connecting flanges and pipes of the pump are closed with plugs or plugs, and critical connectors and openings of the inlet and pressure pipes are sealed.

In pumps weighing more than 1000 kg or on their foundation frames (plates), control devices are provided to align their position on the foundation and the place for leveling. Places for level installation are indicated on the installation drawing. Before testing the pump, the electric motor is started separately to check the direction of rotation, the absence of vibration, and the temperature of the bearings, after which the coupling halves are connected, and the joint operation of the electric motor with the pump is tested, first at idle and then under load. Wheel and rotor assemblies must be balanced. The root mean square value of the vibration velocity measured on the pump bearing housings should not be more than 7 mm/s during manufacture and 11 mm/s during operation, and the temperature of the metal and oil of the bearings should not be more than 35-40 °C higher than the temperature ambient air. It is necessary to ensure continuous monitoring of their proper condition during operation of the feed pumps.

Regularly check the pump instrumentation, maintain the feed water pressure after the pumps and monitor the water pressure before the pump in accordance with the pump operating instructions. Post posters near the valves on the discharge pipes of the pumps with the inscription that the unloading line must be turned on:

When starting the pump;

When idling;

When the load is reduced to the maximum permissible for the reliability of pump operation in accordance with the production instructions, but not lower than 20% of its rated capacity.

In addition, have at the workplace a diagram of feeding and deaeration installations with all related equipment and fittings, instructions for servicing installations related to the supply of steam boilers.

The instructions must indicate the procedure for personnel to prevent and eliminate possible malfunctions and accidents.

It is not allowed to put the feed pump into operation, nor to operate it at idle speed, with the valve on the discharge side closed, without bypassing water through the recirculation (discharge) line for more than three minutes.

It is important to ensure that the valves on the suction and discharge pipes of the standby feed pumps are open.

When taking the pump out for repair or into reserve, it is necessary to turn off its electric motor only after closing the discharge valve (with the preliminary opening of the recirculation line).

If the feed pump remains in reserve, after stopping it completely, it is necessary to reopen the valve on the discharge pipe and check whether the motor rotor is rotating.

If, in the event of a leak in the check valve, the pump rotates in the opposite direction, then you must immediately close the discharge valve at the pump and take it out for repairs.

It is necessary to equip an ATS - an automatic device for starting the backup pump when the pressure in the pressure line decreases and periodically, according to a schedule, check its operation (mandatory for all electric-driven feed pumps).

In addition, a separate recirculation (discharge) line with a restrictive washer is installed from each feed pump, connected to the deaerator or feed tank (but not to the suction line of the feed pumps). The outlet to the unloading line is made before the pump check valve. If the unloading lines for pumps of the same type are combined, then a check valve is installed on each of them.

Combining the discharge lines of electric and turbo pumps is prohibited!

When operating feed pumps, the temperature of the bearings and their drives must not be allowed to rise above 70 o C; if necessary, replace the lubricant in the bearings or in the lubrication system.

Noise and shock in the pump are observed when:

If the coupling halves are bored incorrectly;

Static deflection of the shaft;

Knock of bearings;

Turn short circuit in the electric motor;

The impeller touching the seals;

In case of unacceptable heating of bearings;

When cavitation occurs.

A noticeable decrease in pump performance after some time of normal operation can be caused by:

Increased gap losses inside the pump;

Increasing water temperature;

High resistance of the suction pipeline (pump steaming);

Impeller clogging and wear;

Air entering the pump and suction pipe.

Feed pumps are placed below the deaerator feed water tanks to avoid interruption of the hot water flow due to its boiling. The formation of steam bubbles in the suction pipe of the pump leads to hydraulic shocks in the supply pipelines and disruption of the water supply to the pump, which can cause an accident.

The main reasons for “steaming” PEN are:

1. A sharp decrease in water level or pressure in the deaerator;

2. A sharp decrease in feedwater consumption with a closed recirculation line;

3. A sharp increase in the supply of feed water to the pump when the suction grid is clogged;

4.Increasing the resistance on the unloading line from the hydraulic heel chamber;

5. Increased leakage through the hydraulic foot chamber.

Let's consider only two main reasons, because... Under no circumstances should the pump be allowed to “steam”, which can quickly lead to its failure.

1. A sharp decrease in water level or pressure in the deaerator.

This can be caused by:

1.1. if the readings of the electronic level gauge are unreliable, check it and duplicate it against the level glass installed in the feed water accumulator tank;

1.2. clogging of the filter mesh at the pump suction.

The filter mesh on the PEN suction has two conical bodies, inserted one into the other, between which a brass mesh is sandwiched. The inner conical body of the mesh consists of vertical wire rods with a diameter of 6.0 mm with wire wound on them with a diameter of 1.0 mm. The outer conical body of the mesh is made of 4.0 mm thick perforated steel sheet with 22,000 holes with a diameter of 4.0 mm.

For periodic purging and washing of the filter, there are two pipes for supplying the main condensate from the condensate pumps and removing dirt from the bottom of the filter. Blowing can be done with the pump running, and flushing only with the pump stopped;

1.3.closing the main condensate supply control valve.

Urgently check at the control room whether the circuit on the regulator's electric drive is assembled, immediately contact the deaerator operator's lineman, request that the regulator's bypass be manually opened and check the opening of the main condensate supply valve through the deaerator's vapor cooler. A sharp decrease in the level of feed water in the deaerator accumulator tank while the feed pump is running can lead to the formation of a funnel at the pump suction and to its failure, because the pump cannot operate on water steam;

1.4. closing the heating steam regulator in the deaerator leads to a decrease in steam pressure in its body. Urgently open the regulator bypass and manually check the operation of the regulator itself;

1.5. unauthorized opening of the electric valve for supplying cold, chemically demineralized water to the deaerator for emergency replenishment and pre-start filling of the deaerator. This leads to a sharp decrease in steam pressure in the deaerator and can lead to boiling of the entire volume of water in the deaerator body and to its destruction.

2. A sharp decrease in feedwater consumption when the recirculation line is closed. This can be caused by:

2.1. If the flow meter reading is incorrect, check its readings;

2.2. spontaneous closing of the pressure valve due to a short circuit in its electric drive;

2.3. breakage of the electric motor-pump coupling. Urgently check the current load of the electric motor. If the coupling breaks, the ammeter will show the no-load current of the electric motor, i.e. less than rated current. A mechanical check valve is installed on the pump discharge pipe, which serves to prevent the pump from “steaming” when the feed water flow rate decreases. The check valve is equipped with an automatic recirculation line that ensures a flow rate of at least 30% of the rated pump flow rate when the pressure valve is closed.

“Steaming” of the pump is expressed by the occurrence of metallic contact between the stationary and rotating parts of the pump as a result of a break in the continuity of the water flow, which causes intense steam formation in the pump. When “steaming,” strong shocks and noises are observed at the water inlet to the pump, a decrease in pressure at the pump head, and a sharp fluctuation in the current load of the pump electric motor.

Types and types of feed centrifugal pumps

PE type electric feed pumps supply water with temperatures up to 165 °C to drum and direct-flow steam boilers and are designed to supply water to stationary steam boilers of thermal power plants operating on organic fuel.

Pumps with nominal flows of 380 and 580 m 3 /h can be operated with or without a fluid coupling; 600 m 3 /h - only with fluid coupling; 710 m 3 /h - without fluid coupling; 780 m 3 /h - can be equipped with a synchronous variable frequency electric drive.

The group of feed pumps also includes pumps of two types PE and TsVK and are designed to supply steam boilers with water that does not contain solid particles. Structurally, they are horizontal sectional multistage pumps with one-sided impellers and are divided into single-casing and double-casing.

Six-stage single-casing pumps PE65/40, PE65-53, PE150-53 and PE150-63 are designed for boilers with a steam pressure of 40 kgf/cm2. The material of the flow part is gray cast iron SCh20.

The ten-stage single-casing pump PE270-150-3 is designed for boilers with a pressure of 100 and 140 kgf/cm2. The material of the flow part is steel.

The shaft supports are two plain bearings with water cooling chambers.

The design of the pumps provides for cooling of the seals with water. Water is supplied to the seal assembly to condense vapors from the pumped liquid, which may leak through the seal. The axial force acting on the pump rotor is absorbed by a hydraulic heel cast from modified cast iron.

The two-casing design is represented by pumps: ten-stage PE380-185-3, ΠE500-180-3, ΠE580-195 and eleven-stage PE380-200-3 for subcritical boilers with a steam pressure of 140 kgf/cm2, seven-stage pump PE600-300-3 for supercritical boilers with steam pressure 255 kgf/cm2.

Digital designation of pumps: the first digit is the flow m3/hour, the second is the pressure in kgf/cm2 (atm).

With the development of nuclear energy, special feed pumps for nuclear power plants were created, which are not intended for a wide range of consumers and are designated by the letter A, i.e. only for nuclear power plants.

Feeding centrifugal vortex cantilever pumps of the TsVK type are designed for pumping water and other neutral liquids with temperatures up to 105 °C, containing solid inclusions up to 0.05 mm in size, with a concentration of no more than 0.01% by weight.

Rice. P-7. Section of a PE type feed pump (Feed pump with Electric Drive) 1 - shaft, 2 - bearing, 3 - mechanical seal, 4 - inlet cover, 5 - ring inlet, 6 - pre-connected wheel, 7 - cover, 8 - impeller, 9 - section ; 10 - guide vane, 11 - pump casing, 12 - internal housing, 13 - pressure cover, 14 - shaft end seal housing; 15 - rotor stop, 16 - unloading disk; 17 - auxiliary pipelines; 18 – outer casing, 19 – plate.

Rice. P-8. Section of a TsVK type pump: 1 - cover, 2 - centrifugal wheel; 3 - insert I; 4 - vortex wheel, 5 - insert II; 6 - mechanical seal, 7 - housing, 8 - shaft

In the digital designation of the pump, the numerator of the fraction is flow (l/sec.), the denominator is pressure (m.water column). Structurally, they are a cantilever horizontal pump with two impellers. The impeller of the first stage is centrifugal, the second stage is vortex. This combination makes it possible to obtain normal suction conditions with the first stage (permissible vacuum suction height -7 m), and with the second stage - high pressure. The material of the flow part is cast iron, the vortex wheel is 35L steel. The shaft seal is mechanical; it is possible to install an oil seal with soft packing. The pumps can be equipped with explosion-proof electric motors. Currently, the following manufacturing plants are operating for the production of pumps and equipment for them: OJSC Livgidromash, FSUE Turbopump, OJSC Bobruisk Machine-Building Plant, OJSC Shchelkovo Pump Plant, CJSC Kataysky Pump Plant, CJSC Yasnogorsk Machine-Building Plant", "Sumy Machine-Building Plant", JSC "Uralgidromash", JSC "Vakuummash", JSC "Moldovahidromash", JSC "Rybnitsa Pump Plant", JSC "Gornas", JSC "Prompribor", JSC "Kusinsky Machine-Building Plant".

Literature

Main literature

1. Bystritsky G.F. Fundamentals of energy. Textbook: M., Infra-M. 2007.

2. Zalutsky E.V. and others. Pumping stations.-Kyiv. "Vishcha school". 2006.

3. Modern thermal power engineering / ed. Trukhnia A.D./ MPEI. 2007.

4. Soloviev Yu.P. Auxiliary equipment at power plants. M.: Publishing house MPEI. 2005.

5. Sterman L.S., Lavygin V.M., Tishin S.G. Thermal and nuclear power plants. – M.: Publishing house MPEI. 2007.

6. Thermal and nuclear power plants. /Ed. A.V. Klimenko/, vol. 3. MPEI. 2004.

7. Thermal power plants: Textbook for universities/Ed. E.D.Burova and others. M.: MPEI. 2007.

8. Tiator I.N. Pumping equipment for heating systems. – M.: Publishing house MPEI. 2006.

additional literature

9. Budov V.M. NPP pumps. - M.: Energoatomizdat. 1986.

10. Gorshkov A.M. Pumps.- M.-L.: Mechanical Engineering. 1947.

11. Karelin V.Ya. Pumps and pumping stations. - M.: Energy. 1996.

12. Krivchenko G.I. Hydraulic machines. Turbines and pumps. M.: Energy. 1988.

13. Lomakin A.A. Centrifugal and axial pumps. - M.: Mechanical Engineering. 1976.

14. Malyushenko V.V. Energy pumps. - M.: Energy. 1981.

15. Malyushenko V.V., Mikhailov A.K. Pumping equipment for thermal power plants. - M.: 1975.

16. Rychagov V.V. etc. Pumps and pumping stations. - M.: Kolos. 1988.

17. Stepanov A.I. Centrifugal and axial pumps. M.: Mashgiz. 1960.

18. Heat engineering reference book. T.1., M.: Energy. 1975.

19.Cherkassky V.M. Pumps, fans, compressors. - M.: Energy. 1994.

20.Chinyaev I.A. Vane pumps. Reference manual. - M.: Mechanical Engineering. 1992.

21. Sherstyuk A.N. Pumps, fans, compressors. - M.: Higher school. 1972.

22. Engel-Kron I.V. Construction and repair of equipment in turbine shops of power plants. - M.: Higher school. 1971.

Pumps- machines for creating a pressure flow of a liquid medium. When developing hydraulic systems and networks, the correct selection and use of pumps allows us to obtain the specified parameters for the movement of fluids in hydraulic systems. In this case, the designer needs to know design features of pumps, their properties and characteristics. In this section you can download for free and without registration books on centrifugal, vane, gear pumps and ventilators.

	Name:Pumps, fans, compressors: A textbook for thermal power engineering specialties at universities.
	Cherkassky V. M.
	Description:Classifications, fundamentals of theory, characteristics, control methods, designs and operating issues of machines for supplying liquids and gases used in energy and other industries are considered.
	The year of publishing: 1984
	Views: 36579 | Downloads: 6834

	Name:Gear pumps for metal-cutting machines.
	Rybkin E.A., Usov A.A.
	Description:The book contains an analysis of theoretical and experimental studies of methods for calculating and designing gear hydraulic pumps used in hydraulically powered metal-cutting machines.
	The year of publishing: 1960
	Views: 35392 | Downloads: 893

Ministry of Education and Science of the Russian Federation Federal State Budgetary Educational Institution of Higher Professional Education

"Yaroslavl State Technical University" Department of "Processes and Apparatuses of Chemical Technology"

CALCULATION OF PUMPING INSTALLATION

Tutorial

Compiled by: Ph.D. tech. Sciences, associate professor V. K. Leontyev, assistant M. A. Barasheva

Yaroslavl 2013

ANNOTATION

The tutorial covers brief theoretical information on the calculation of simple and complex pipelines, and the calculation of the main parameters of pump operation. Examples of pipeline calculations and pump selection are given. Multi-variant tasks have been developed to perform calculation and graphic work.

Particular attention in the manual is paid to the designs of dynamic pumps and positive displacement pumps.

The textbook is intended for students performing calculation work and course projects in the courses “Hydraulics”, “Mechanics of Liquids and Gas” and “Processes and Apparatuses of Chemical Technology”.

	Name:Pumps, fans and compressors. Study guide for colleges.
	Sherstyuk A.N.
	Description:The book outlines the basics of the theory, calculation and operation of blade machines - pumps, fans and compressors.
	The year of publishing: 1972

INTRODUCTION
1. Hydraulic calculation of pipelines
1.3. Complex pipelines
1.3.1. Series connection of pipelines
1.3.2. Parallel connection of pipelines
1.3.3. Complex branched pipeline
2. Calculation of the pumping unit
2.1. Pump operating parameters
2.1.1. Determining the pressure of a pumping unit
2.1.2. Measuring the head of a pumping unit using
devices
2.1.3. Determination of useful power, shaft power,
pumping unit efficiency
3. Pump classification
3.1. Dynamic pumps
3.1.1. Centrifugal pumps
3.1.2. Axial (propeller) pumps
3.1.3. Vortex pumps
3.1.4. Jet pumps
3.1.5 Air (gas) lifts
3.2 Positive displacement pumps
3.2.1 Piston pumps
3.2.2 Gear pumps
3.2.3 Progressive cavity pumps
3.2.4 Vane pumps
3.2.5 Montaju
3.3 Advantages and disadvantages of various types of pumps
4. Assignment for calculating a pumping unit
Exercise 1
4.1. Example of calculation of a simple pipeline
Task 2
4.2. Example of complex pipeline calculation
Task 3
4.3. Example of pumping installation calculation
Task 4
4.4. An example of calculation and selection of a pump for supplying liquid to a
BIBLIOGRAPHICAL LIST
APPENDIX A
APPENDIX B
APPENDIX B

INTRODUCTION

In chemical production, most technological processes are carried out with the participation of liquid substances. These are raw materials that are supplied from the warehouse to the processing plant, these are intermediate products moved between devices, installations, and workshops of the plant, and these are the final products delivered to the containers of the finished product warehouse.

All movement of liquids, both horizontally and vertically, requires energy. The most common source of energy for fluid flow is a pump. In other words, the pump creates a pressure flow of liquid.

The pump is an integral part of a pumping unit, which includes suction and discharge (pressure) pipelines; source and receiving tanks (or technological devices); regulating pipeline fittings (taps, valves, gate valves); measuring instruments.

A correctly selected pump must provide a given fluid flow rate in a given pumping unit, while operating in an economical mode, i.e. in the area of ​​maximum efficiency.

When choosing a pump, it is necessary to take into account the corrosive and other properties of the pumped liquid.

1. HYDRAULIC CALCULATION OF PIPELINES

1.1. Pipeline classification

The role of pipeline systems in the economy of any country, individual corporation, or simply an individual economy cannot be overestimated. Pipeline systems are currently the most efficient, reliable and environmentally friendly transport for liquid and gaseous products. Over time, their role in the development of scientific and technological progress increases. Only with the help of pipelines is it possible to unite hydrocarbon producing countries with consuming countries. A large share in the pumping of liquids and gases rightfully belongs to gas and oil pipeline systems. In almost every machine and mechanism, pipelines play a significant role.

According to their purpose, pipelines are usually distinguished by the type of products transported through them:

– gas pipelines;

– oil pipelines;

– water pipelines;

– air ducts;

– product pipelines.

Based on the type of movement of liquids through them, pipelines can be divided into two categories:

– pressure pipelines;

– non-pressure (gravity) pipelines.

In the pressure pipeline, the internal absolute pressure of the transported medium is more than 0.1 MPa. Gravity pipelines operate without excess pressure; the movement of the medium in them is ensured by a natural geodetic slope.

Based on the magnitude of pressure losses due to local resistance, pipelines are divided into short and long.

IN in short pipelines, pressure losses due to local resistance exceed or equal 10% of the pressure losses along the length. When calculating such pipelines, pressure losses due to local resistance must be taken into account. These include, for example, oil pipelines of volumetric transmissions.

Long pipelines include pipelines in which local losses are less than 10% of the pressure losses along the length. Their calculation is carried out without taking into account losses due to local resistance. Such pipelines include, for example, main water pipelines and oil pipelines.

According to the pipeline operation scheme, they can also be divided into simple

and complex.

Simple pipelines are series-connected pipelines of the same or different sections that do not have any branches. Complex pipelines include pipe systems with one or more branches, parallel branches, etc.

Depending on the change in the flow rate of the transported medium, pipelines are divided into:

– transit;

– with travel expenses.

In transit pipelines, liquid is not withdrawn as it moves; the flow rate remains constant; in pipelines with travel flow, the flow rate varies along the length of the pipeline.

Pipelines can also be divided according to the type of cross-section: into pipelines with a round and non-circular cross-section (rectangular, square and other profiles). Pipelines can also be divided according to the material from which they are made: steel pipelines, concrete, plastic, etc.

1.2. Simple pipeline of constant cross-section

The main element of any pipeline system, no matter how complex it may be, is a simple pipeline. A simple pipeline, according to the classical definition, is a pipeline assembled from pipes of the same diameter and the quality of its internal walls, in which a transit fluid flow moves, and on which there are no local hydraulic resistances. Let's consider a simple pipeline of constant cross-section, having a total length l and a diameter d, as well as a number of local resistances (valve, filter, check valve).

Rice. 1.1 Simple pipeline diagram

The cross-sectional size of the pipeline (diameter or hydraulic radius size), as well as its length (length) of the pipeline (l, L) are the main geometric characteristics of the pipeline. The main technological characteristics of the pipeline are the fluid flow in the pipeline Q and the pressure H (at the head structures of the pipeline, i.e. at its beginning). Most of the other characteristics of a simple pipeline are, despite their importance, derived characteristics. Since in a simple pipeline the fluid flow is transit (the same at the beginning and end of the pipeline), the average speed of fluid movement in the pipeline is constant ν = cons’t.

Let's write down Bernoulli's equation for sections 1-1 and 2-2.

h p,

where z 1, z 2 – distance from the comparison plane to the centers of gravity of the selected sections – geometric head, m;

		P1, P2					– pressure at the center of gravity of the selected sections, Pa;
		– flow density, kg/m3;
		g – free fall acceleration, m/s2;
								– average flow speed in the corresponding section;
	h p – pressure loss in the pipeline, m;
								g – piezometric pressure, m;
					2 g – velocity head, m.

Since the pipeline cross-section is constant, the flow speed is the same along the entire length of the pipeline, and, accordingly, the velocity pressures in sections 1-1 and 2-2 are equal. Then Bernoulli's equation takes the following form:

					h p .

Pressure losses in a pipeline are composed of pressure losses due to friction and local resistance; according to the principle of addition, pressure losses in a pipeline can be defined as:

where is the friction coefficient; l – pipeline length, m;

d – internal diameter of the pipeline, m:

– sum of local resistance coefficients.

The amount of pressure loss is directly related to the fluid flow in the pipeline.

In this way, the pressure loss in the pipeline can be determined

				2 g S

The dependence of the total pressure loss in the pipeline on the volumetric flow rate of liquid h p f (Q) is called the pipeline characteristic.

In the case of a turbulent mode of motion, assuming the quadratic law of resistance (= cons’t), the following expression can be considered a constant:

Rice. 1.2 Pipeline characteristics

1 – characteristics of the pipeline in laminar mode of fluid movement; 2 – characteristics of the pipeline under turbulent motion conditions

The required pressure is the piezometric pressure at the beginning of the pipeline, according to Bernoulli’s equation:

H consumption			z 2 z 1		h p .

Thus, the required pressure is spent on lifting the liquid to a height z z 2 z 1, overcoming the pressure at the end of the pipeline and overcoming the resistance of the pipeline.

The sum of the first two terms in formula (1.9) is a constant value, it is called static pressure:

The dependence of the required pipeline pressure on the volumetric flow rate of liquid H inflow f (Q) is called network characteristics. In laminar flow, the required pressure curve is a straight line; in turbulent flow, it has

1.3. Complex pipelines

TO complex pipelines should include those pipelines that do not fit into the category of simple ones, i.e. Complex pipelines include: pipelines assembled from pipes of different diameters (series connection of pipelines), pipelines with branches: parallel connection of pipelines, pipeline networks, pipelines

With continuous liquid distribution.

1.3.1. Series connection of pipelines

When connecting pipelines in series, the end of the previous simple pipeline is simultaneously the beginning of the next simple pipeline.

Let's consider several pipes of different lengths, different diameters and containing different local resistances, which are connected in series (Figure 1.4).

Rice. 1.4 Series piping diagram

Section one. Pumps

Chapter I. Purpose, principle of operation and areas of application of various types of pumps
§ 1. Basic parameters and classification of pumps
§ 2. Design diagrams and operating principles of vane pumps
§ 3. Design diagrams and operating principles of friction pumps
§ 4. Design diagrams and principles of operation of volumetric pumps
§ 5. Advantages and disadvantages of pumps of various types

Chapter 2. Working process of vane pumps
§ 6. Pressure developed by the pump
§ 7. Pump power and its efficiency
§ 8. Kinematics of fluid movement in the working parts of pumps
§ 9. Basic pump equation. Theoretical pressure
§ 10. The influence of the actual nature of the movement of fluid in the pump impeller on the value of the theoretical pressure
§ 11. Similarity of pumps. Conversion formulas and speed factor
§ 12. Suction height of pumps
§ 13. Cavitation in pumps. Permissible suction lift

Chapter 3. Characteristics and operating mode of vane pumps
§ 14. Theoretical. Pump characteristics
§ 15. Methods for obtaining pump characteristics
§ 16. Changes in pump characteristics with changes in rotation speed and geometric dimensions of the impeller
§ 17. Unsteady and transient operating modes of pumps

Chapter 4. Pumps and network work together
§ 18. Pipeline characteristics and actual pump flow
§ 19. Regulation of pump operation
§ 20. The influence of the hydrological characteristics of the water source and the design features of the network on the operating mode of the pumps
§ 21. Parallel operation of pumps
§ 22. Sequential operation of pumps
§ 23. Parallel operation of well pumps

Chapter 5. Design of pumps used for water supply and sewerage
§ 24. Centrifugal cantilever pumps
§ 25. Double-entry centrifugal pumps
§ 26. Centrifugal vertical pumps
§ 27. Multistage centrifugal pumps
§ 28. Borehole pumps
§ 29. Axial pumps
§ 30. Dynamic pumps for wastewater
§ 31. Water ring pumps
§ 32. Blowers
§ 33. Metering pumps
§ 34. Water jet pumps
§ 35. Special pumps

Chapter 6. Pumps used in construction work
§ 36. Ground pumps
§ 37. Centrifugal sand pumps
§ 38. Mortar pumps
§ 39. Concrete pumps
§ 40. Screw pneumatic pumps for cement

Section two. Pumping stations

Chapter 7. Types of pumping stations for water supply and sewerage systems
§ 41. Purpose of pumping stations. Basic requirements for their structures and equipment
§ 42. Schematic diagrams of pumping stations
§ 43. Types of pumping stations

Chapter 8. Main power and auxiliary equipment of pumping stations
§ 44. Composition of pumping station equipment
§ 45. Drive motors of pumps of various types
§ 46. Garbage-containing devices
§ 47. Gates, valves, valves
§ 48. Lifting and transport mechanisms
§ 49. Equipment for pump filling systems, technical water supply, drainage and drainage
§ 50. Control and measuring equipment of pumping stations
§ 51. Pipes and fittings of intrastation communications

Chapter 9. Selection of basic equipment for pumping stations
§ 52. Requirements for the selection of design operating modes of pumping stations
§ 53. Calculation of the operating mode of pumping stations
§ 54. Features of water management calculations for industrial pumping stations
§ 55. Determination of design pressure
§ 56. Selection of the type and number of installed pumps
§ 57. Determination of the permissible suction height and foundation level of the pumping unit
§ 58. Determination of drive motor power

Chapter 10. Water supply pumping stations
§ 59. Specific features of water pumping stations
§ 60. Basic design solutions for pumping station buildings
§ 61. Suction pipelines
§ 62. Pressure pipelines
§ 63. Location of pumping units and determination of the main dimensions of the pumping station building
§ 64. Underground part of the pumping station building Foundations and/supporting structures
§ 65. Upper structure of the pumping station building
§ 66. Pumping stations of the first rise
§ 67. Pumping stations of the second rise
§ 68. Pumping stations and installations for groundwater intake
§ 69. Boosting pumping stations
§ 70. Circulation pumping stations
§ 71. Mobile pumping stations

Chapter 11. Sewage pumping stations
§ 72. Purpose of sewer pumping stations; their main elements
§ 73. Classification of sewage pumping stations; device diagrams
§ 74. Receiving tanks of sewage pumping stations
§ 75. Location of pumping units
§ 76. Features of the design of suction and pressure pipelines
§ 77. Water supply to sewage pumping stations
§ 78. Designs of sewage pumping stations
§ 79. Special types of sewage pumping stations

Chapter 12. Electrical part of pumping stations
§ 80. Electrical equipment for pumping stations
§ 81. Electrical connection diagrams
§ 82. Transformer substations and distribution devices

Chapter 13. Automation of pumping stations
§ 83. Basic elements of automation systems
§ 84. Schematic diagrams of automatic control
§ 85. Schemes of automated pumping units and pumping stations

Chapter 14. Operation of pumping stations
§ 86. Basic provisions of the rules for the technical operation of pumping stations
§ 87. Operating reliability parameters and measures to improve them
§ 88. Wear and tear of pumping station equipment
§ 89. Preventive and major repairs of equipment
§ 90. Full-scale tests of pumping station units

Chapter 15. Technical and economic indicators of pumping stations
§ 91. Specific technical and economic indicators and their definition
§ 92. Technical and economic comparison of options for the designed pumping station

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