An ejector is a device in which kinetic energy is transferred from one medium moving at a higher speed to another.
A pump is an actuator that converts mechanical energy from a motor (drive) into hydraulic energy from a fluid flow. The pump, driven by the engine, communicates with the tanks with two pipelines: suction (intake) and discharge (discharge).
According to the principle of operation, marine pumps are divided into three groups: positive displacement (displacement), vane and jet. Jet pumps have no moving parts and create a differential pressure using a working medium: liquid, steam or gas, supplied to the pump under pressure. These pumps include ejectors and injectors.
Jet pumps connected to the object to be serviced by a suction pipe are called ejectors. For ejectors, the working head is higher than the useful one, that is. Ejectors are divided into water - for dehumidification, steam - for air suction and creating a vacuum in condensers, evaporators, etc.
Jet pumps connected to the object to be serviced by a discharge pipe are called injectors. For injectors, the pressure ratio is reversed, that is, the effective pressure is higher than the working one. Injectors include steam jet pumps for supplying feed water to steam generators.
Figure 1 shows a water jet dewatering ejector of the VEZh type.
The ejector body 3, welded from sheet copper, has the shape of a diffuser with an angled suction pipe 7, the opening of which is closed by a cap 6 with a chain. On the left, a brass nozzle 2 is inserted into the body, in the form of a converging nozzle with a half-nut "curtain" 1 for connecting a flexible hose through which working water is supplied to the ejector. To connect the outlet hose to the ejector, a half-nut of the curtain 4, located at the outlet end of the discharge pipe 5. This connection provides the operation of portable ejectors, which are installed on the thread of the deck bushings, communicating by means of tubes with compartments or holds that require draining.
Rice. 1 Water-jet ejector type VEZH
The ejector works as follows: the working water is usually supplied from the fire main under pressure to the nozzle. From the outlet narrow section of the nozzle, water flows at high speed into the so-called mixing chamber, while the pressure decreases. Passing through the narrow section of the diffuser (“throat”), the water entrains the air and creates a vacuum in the mixing chamber, which ensures the flow of liquid from the suction pipe 7. Due to friction and as a result of the exchange of impulses, the sucked water mixes, is captured and moves along with the working water. The mixture enters the expanding part of the diffuser, where the kinetic energy (speed) decreases and, due to this, the static head increases, which contributes to the injection of the liquid mixture through the nozzle 5 into the discharge pipeline and overboard. The flow of the ejector can be adjusted by screwing in or out of the nozzle.
Figure 2 shows a steam jet injector used to power steam boilers.
Working steam from the boiler is supplied to branch pipe 1 of the injector. The valve 2 is opened by turning the handle 10. The steam, passing through the steam nozzle 9, acquires a high speed due to the decrease in pressure. At the same time, it entrains air particles with it and creates a vacuum, which ensures that feed water enters the pump through the nozzle 3. The incoming water, mixing with steam, condenses it. The decrease in volume increases the vacuum in the mixing chamber 4, which ensures continuous suction of feed water into the injector. A mixture of condensate and water flows through a diffuser 6 to a non-return valve 5, which covers the entrance to the boiler feed pipe. As a result of the transfer of part of the kinetic energy of the mixture into pressure, the valve opens and hot water enters the steam boiler. 
Rice. 2 Steam jet injector
If the discharge pressure before valve 5 is less than the pressure in the boiler, the valve will not open. In this case, the water mixture in the chamber 7 will squeeze the vestibule valve and pour out through the hole 8.
When the pressure becomes sufficient to open the valve 5, the pressure in the chamber 7 will decrease and the vest valve will close under the action of the spring, preventing the flow of water outside. Steam injectors have a simple design and provide hot feed water to the steam boiler, but are inefficient and uneconomical.
The absence of moving parts in the jet pump ensures the pumping of liquid with various mechanical impurities, which is used on ships of the fishing industry for pumping slurry, that is, a mixture of fish with water by airlift pumps or hydraulic elevators. Unlike centrifugal fish pumps, airlifts do not damage fish when pumping slurry. Compressed air is used as a working medium in airlifts, which, when mixed with water, creates a reduced density for it.
The main disadvantage of jet pumps is their low efficiency, which usually does not exceed that of airlifts.
The ejector workflow is as follows. A high-pressure (ejection) gas at full pressure flows out of the nozzle into the mixing chamber. In a stationary mode of operation of the ejector, a static pressure is established in the inlet section of the mixing chamber 
which is always below the total pressure of the low-pressure (ejected) gas 
.
Under the influence of the pressure difference, the low-pressure gas rushes into the chamber. The relative flow rate of this gas, called the ejection coefficient 
, depends on the areas of the nozzles, on the density of gases and their initial pressures, on the mode of operation of the ejector. Despite the fact that the velocity of the ejected gas in the inlet section 
usually less than the velocity of the propelling gas 
, by proper selection of nozzle areas 
and 
an arbitrarily large value of the ejection coefficient n can be obtained.
The ejected and ejected gases enter the mixing chamber in the form of two separate streams: in the general case, they can differ in chemical composition, velocity, temperature and pressure. The mixing of flows means, ultimately, the equalization of the parameters of the gases over the entire section of the chamber.
The whole mixing process can be roughly divided into two stages - initial and main. Accordingly, two sections of the mixing chamber are distinguished (Fig. 5). With a known approximation, the flow in the initial section of the mixing chamber can be similar to a turbulent jet moving in a cocurrent flow. Due to the presence of transverse fluctuating velocity components characteristic of turbulent motion, the flows penetrate into each other, forming a gradually broadening mixing zone - the boundary layer of the jet. Within the boundary layer, there is a smooth change in the parameters of the gas mixture from their values in the ejected gas to the values in the ejected gas. Outside the boundary layer, in the initial section of the mixing chamber, there are unperturbed flows of ejected and ejected gases.
In the initial section of the chamber, particles of the ejected gas are continuously captured by the high-pressure jet and carried away into the mixing zone. Due to this, a vacuum is maintained at the inlet to the mixing chamber, which ensures the inflow of low-pressure gas into the ejector.
Depending on the relative dimensions of the ejector, with distance from the nozzle, both zones of undisturbed gas flow successively disappear; so, in fig. 5, the core of the ejection jet is eliminated first.
At some distance from the nozzle, in the section Г - Г, called the boundary section, the boundary layer of the jet fills the entire section of the mixing chamber. There are no regions of undisturbed flows in this section, but the gas parameters are significantly different along the radius of the chamber. Therefore, even after the boundary section in the main section of the mixing chamber, the alignment of the flow parameters along the section continues. In the final section of the chamber, at an average distance of 8 - 12 chamber diameters from the initial section, a fairly homogeneous mixture of gases is obtained, the total pressure of which is 
more than the total pressure of the ejected gas 
, the smaller the ejection coefficient n. The rational design of the ejector is reduced to the choice of its geometric dimensions so that, for given initial parameters and the ratio of gas flow rates, to obtain the highest value of the total pressure of the mixture, or at given initial and final pressures, to obtain the highest ejection coefficient.
Rice. 5. Changing the velocity field along the length of the mixing chamber.
The above-described scheme of the process of mixing gases in an ejector at subsonic speeds is fundamentally no different from the process of mixing incompressible liquids in a liquid ejector. As will be shown below, even at large subcritical pressure ratios, not only qualitative regularities, but also many quantitative relationships between the parameters of a gas ejector practically do not differ from the corresponding data of a liquid ejector.
A qualitatively new flow pattern is observed at supercritical pressure ratios in the nozzle. In subsonic outflow, the gas pressure at the nozzle outlet is equal to the pressure in the environment, in other words, the static gas pressures at the inlet to the mixing chamber p 1 and p 2 are the same. With a sonic or supersonic outflow of an ejected gas, the pressure at the nozzle exit can differ significantly from the pressure of the ejected gas.
If the nozzle of the ejected gas is made non-expanding, then at a supercritical pressure ratio, the static pressure at the nozzle cut exceeds the pressure in the environment - the ejected gas.
Rice. 6. Flow diagram in the initial section of the mixing chamber at a supercritical pressure ratio in the nozzle
Therefore, after exiting the nozzle A, the jet of ejecting gas B (Fig. 6), moving at the speed of sound 
, continues to expand, its speed becomes supersonic, and the cross-sectional area is greater than the area of the nozzle outlet.
The supersonic ejection jet flowing from the Laval nozzle behaves in the same way if a supersonic nozzle with incomplete expansion is used in the ejector. In this case, the gas velocity at the nozzle exit corresponds to 
, where 
- the calculated value of the velocity for a given Laval nozzle, which is determined by the ratio of the areas of the outlet and critical sections.
Thus, at pressure ratios greater than the calculated one for a given nozzle, the ejection gas in the initial section of the mixing chamber is an expanding supersonic jet. The flow of ejected gas in this section moves between the boundary of the jet and the walls of the chamber. Since the velocity of the ejected flow in the initial section is subsonic, then during flow through a converging "channel" the flow is accelerated, and the static pressure in it decreases.
With a subsonic outflow of the ejection jet, the highest rarefaction, and the maximum flow rates were achieved in the inlet section of the chamber. In this case, the minimum static pressure and the maximum velocity of the ejected flow are achieved in the 1 "section, located at a certain distance from the nozzle, where the area of the expanding supersonic jet becomes the largest. This section is usually called the choking section.
A feature of a supersonic jet is that its mixing with the surrounding flow in this section is much less intense than mixing of subsonic flows. This is due to the fact that a supersonic jet is more stable than a subsonic jet, and the blurring of the boundaries of such a jet is weaker. The physical foundations of this phenomenon can be easily understood using the following example (Fig. 7).
Rice. 7. Scheme of the force effect of gas on a body that bends the boundary of subsonic (a) and supersonic (b) flows.
If the boundary of the subsonic flow is curved for some reason (for example, the effect of gas particles from the cocurrent flow), then in this place, due to a decrease in the cross-sectional area, the static pressure decreases and an external pressure force arises, which increases the initial deformation of the boundary: upon interaction with the environment the subsonic jet “pulls in” the particles of the external flow and its boundary is quickly blurred. In a supersonic (relative to the external environment) flow, a similar curvature of the boundary and a decrease in the cross section leads to an increase in pressure; the resulting force is directed not inward, but outward of the flow and tends to restore the initial position of the boundary of the jet, pushing out the particles of the external environment.
It is interesting to note that this difference in the properties of subsonic and supersonic jets can be observed literally by touch. The subsonic jet draws inward a light object brought to the boundary, the supersonic jet has a "hard" boundary at a distance of several calibers from the nozzle; when an attempt is made to introduce an object into the jet from the outside, a noticeable resistance of the sharply expressed boundary of the jet is felt.
Rice. 8. Schlieren - photograph of the flow in the mixing chamber of the flat ejector in the subsonic regime of gas outflow from the nozzle; 
,
, p 1 = p 2.
Rice. 9. Schlieren - photograph of the flow in the mixing chamber of a flat ejector at a supercritical pressure ratio in the nozzle P 0 = 3.4.
In fig. Figures 8 and 9 show photographs of the flow in the initial section of the mixing chamber during subsonic and supersonic outflow of the ejection jet. The photographs were taken on a plane model of the ejector, the mode was changed by increasing the total pressure of the ejecting gas in front of the nozzle 
at constant pressure of the ejected gas and constant pressure at the outlet from the chamber.
The photographs show the difference between the two considered flow regimes in the initial section of the chamber.
When analyzing the processes and calculating the parameters of the ejector at supercritical pressure ratios in the nozzle, we will assume that up to the blocking section 
(Fig. 6) the ejected and ejected flows flow separately, without mixing, and intensive mixing occurs behind this section. This is very close to the actual picture of the phenomenon. The blocking section is a characteristic section of the initial mixing section, and the flow parameters in it, as will be shown below, significantly affect the working process and parameters of the ejector.
With distance from the nozzle, the boundary between the flows is blurred, the supersonic core of the ejecting jet decreases, and the gas parameters are gradually equalized over the cross section of the chamber.
The nature of the mixing of gases in the main section of the mixing chamber is practically the same as at subcritical pressure ratios in the nozzle, the velocity of the gas mixture 
in a wide range of initial parameters of gases, a lower speed of sound remains. However, with an increase in the ratio of the initial gas pressures above a certain value determined for each ejector, the flow of the mixture in the main section of the chamber becomes supersonic and can remain supersonic until the end of the mixing chamber. The conditions for the transition from the subsonic to the supersonic regime of the flow of a mixture of gases, as will be shown below, are closely related to the regime of gas flow in the blocking section.
These are the features of the process of mixing gases at supercritical ratios of gas pressures in the ejection nozzle. Note that by the pressure ratio in the nozzle we mean the ratio of the total pressure of the ejecting gas 
to the static pressure of the ejected flow in the inlet section of the mixing chamber 
which depends on the total pressure 
and reduced speed 
.
The more 
, the greater (with a constant ratio of total gas pressures) the pressure ratio in the nozzle:
Here 
is a well-known gas-dynamic function.
Thus, the supercritical regime of the outflow of the ejecting gas from the nozzle can also exist when the ratio of the initial total gas pressures 
below the critical value.
Regardless of the peculiarities of the gas flow during mixing, the velocity of the gases is equalized over the cross section of the chamber by the exchange of impulses between particles moving at a higher and lower speed. This process is accompanied by losses. In addition to the usual hydraulic losses due to friction against the walls of the nozzles and the mixing chamber, losses associated with the very essence of the mixing process are characteristic of the working process of the ejector.
Let us determine the change in kinetic energy that occurs when two gas streams are mixed, the second mass flow rate and the initial velocity of which are, respectively, G 1, G 2, 
and 
... If we assume that the mixing of flows occurs at constant pressure (this is possible either with a special profiling of the chamber, or when mixing free jets), then the amount of movement of the mixture should be equal to the sum of the initial amounts of movement of the flows:
The kinetic energy of the gas mixture is
It is easy to verify that this value is less than the sum of the kinetic energies of the flows before mixing, equal to
by the amount
. (2)
The magnitude 
represents the loss of kinetic energy associated with the process of mixing streams. These losses are similar to the energy losses during the impact of inelastic bodies. Regardless of the temperature, density and other parameters of the flows, the loss, as shown by formula (2), is the greater, the greater the difference in the velocities of the mixing flows. Hence, we can conclude that at a given velocity of the ejected gas and a given relative flow rate of the ejected gas 
(ejection coefficient) to obtain the lowest losses, i.e., the highest value of the total pressure of the gas mixture, it is desirable to increase 
so that the velocity of the ejected gas is as close as possible to the velocity of the ejected gas at the entrance to the mixing chamber. As we will see below, this really leads to the most advantageous flow of the mixing process.
Rice. 10. Change in static pressure along the length of the mixing chamber during subsonic gas flow.
When gases are mixed in the cylindrical mixing chamber of the ejector, the static pressure of the gases does not remain constant. In order to determine the nature of the change in the static pressure in the cylindrical mixing chamber, let us compare the flow parameters in two arbitrary sections of the chamber 1 and 2 located at different distances from the beginning of the chamber (Fig. 10). Obviously, in section 2, located at a greater distance from the inlet section of the chamber, the velocity field is more uniform than in section 1. If we assume that for both sections 
(for the main section of the chamber, where the static pressure changes insignificantly, this approximately corresponds to reality), then from the condition of equality of the second gas flow rates
it follows that, in sections 1 and 2, the area-average value of the flow velocity remains constant
.(3)
. (4)
It is easy to see that for 
, i.e. in the case of a uniform velocity field in section F, the quantity 
is equal to one. In all other cases, the numerator in (4) is greater than the denominator and 
.
The value of the quantity 
can serve as a characteristic of the degree of unevenness of the velocity field in a given section: the more uneven the field 
, the more 
... We will call the quantity 
field coefficient.
Returning to fig. 10, now it is easy to conclude that the value of the field coefficient 
in section 1 is greater than in section 2. The quantities of motion in sections 1 and 2 are determined by the integrals
Because 
, then it follows from here
(5)
So, the amount of motion in the flow during the leveling of the velocity field in the mixing process decreases, despite the fact that the total flow rate and the average velocity over the area 
remain constant.
Let us now write the equation of momenta for the flow between sections 1 and 2:
.
Based on inequality (5), the left side of this equation is always positive. Hence it follows that 
that is, the leveling of the velocity field in the cylindrical mixing chamber is accompanied by an increase in static pressure; there is a reduced pressure in the inlet section of the chamber compared to the pressure at the outlet of the chamber. This property of the process is directly used in the simplest ejectors, consisting of a nozzle and one cylindrical mixing chamber, as, for example, shown in Fig. 10. Due to the presence of a vacuum at the inlet to the chamber, this ejector sucks in air from the atmosphere, and then the mixture is thrown back into the atmosphere. In fig. 10 also shows the change in static pressure along the length of the ejector chamber.
The obtained qualitative conclusion is valid in cases where the change in the gas density in the considered section of the mixing process is insignificant, as a result of which it is possible to approximately consider 
... However, in some cases of admixture of gases of significantly different temperatures, when there is a large non-uniformity of density over the cross section, as well as at supersonic speeds in the main mixing section, when the density changes noticeably along the length of the chamber, the ejector operation modes are possible in which the static gas pressure during mixing does not increases and decreases.
If the mixing chamber is not cylindrical, as assumed above, but has a cross-sectional area that is variable along the length, then an arbitrary change in the static pressure along the length can be obtained.
The main geometrical parameter of an ejector with a cylindrical mixing chamber is the ratio of the area of the outlet cross-sections of the nozzles for the ejected and ejected gases
,
where F 3 is the cross-sectional area of the cylindrical mixing chamber.
High value ejector 
, i.e., with a relatively small area of the chamber, is high-pressure, but cannot work with large ejection coefficients; ejector with small 
allows to suck in a large amount of gas, but slightly increases its pressure.
The second characteristic geometric parameter of the ejector is the expansion ratio of the diffuser 
- the ratio of the cross-sectional area at the outlet of the diffuser to the area at the entrance to it. If the ejector operates at a given static pressure at the outlet of the diffuser, for example, when exhausting into the atmosphere or into a tank with constant gas pressure, then the expansion ratio f of the diffuser significantly affects all parameters of the ejector. With an increase in f, in this case, the static pressure in the mixing chamber decreases, the ejection rate and the ejection coefficient increase with a not very significant change in the total pressure of the mixture. Of course, this is true only until the moment when the speed of sound is reached in some section of the ejector.
The third geometric parameter of the ejector is the relative length of the mixing chamber 
- is not included in the usual methods of calculating the ejector, although it significantly affects the parameters of the ejector, determining the completeness of the equalization of the parameters of the mixture over the section. Below we will assume that the length of the chamber is large enough 
and the field factor 
in its outlet section is close to unity.
Ejection effect-1. The process of mixing two any media, in which one medium, being under pressure, affects the other and carries it in the required direction. 2. Artificial restoration of water pressure during high water and prolonged floods for normal operation of turbines A feature of the physical process - mixing of flows occurs at high velocities of the ejecting (active) flow.
Applying an effect. Increasing the pressure of the ejected stream without direct mechanical energy is used in inkjet devices that are used in various branches of technology:
At power plants - in combustion devices(gas injection burners);
In the power supply system of steam boilers (anti-cavitation water jet pumps);
To increase the pressure from the turbine extractions ( steam jet compressors);
For suction of air from the condenser ( steam jet and water jet ejectors);
· In air cooling systems of generators;
· In heating installations;
· As mixers for heating waters;
· In industrial heat engineering - in the systems of fuel supply, combustion and air supply of furnaces, bench installations for testing engines;
· In ventilation units - to create a continuous flow of air through ducts and rooms;
· In plumbing installations - for lifting water from deep wells;
· For transportation of solid bulk materials and liquids.
Gyroscope(or top) is a massive symmetric body rotating at high speed around the axis of symmetry .
Gyroscopic effect - preservation usually directions axis of rotation freely and rapidly rotating bodies, accompanied under certain conditions, as precession
(movement of the axis along a circular conical surface), and nutation
(oscillatory movements (tremors) of the axis of rotation;
Centrifugal force is the force that, when the body moves along a curved line, makes the body leave the curve and continue the path tangentially to it. The centripetal force is opposite to the centripetal force, which makes a body moving along a curve strive to approach the center; from the interaction of these two forces, the body receives curvilinear motion.
Doppler effect - a change in the frequency and wavelengths recorded by the receiver, caused by the movement of their source and / or the movement of the receiver.
Application: determining the distance to the object, the speed of the object, the temperature of the object.
Diffusion- mutual penetration of contacting substances due to the thermal motion of the particles of the substance. Diffusion takes place in gases, liquids and solids.
Application: in chemical kinetics and technology for the regulation of chemical reactions, in the processes of evaporation and condensation, for the bonding of substances.
Hydrostatic pressure- pressure at any point of the fluid at rest. Equal to the sum of the pressure on the free surface (atmospheric) and the pressure of the liquid column located above the point under consideration. It is the same in all directions (Pascal's law). Determines the hydrostatic force (buoyancy force, holding force) of the vessel.
An ejector is a device that is designed to transfer kinetic energy from one medium moving at a higher speed to another. The operation of this device is based on the Bernoulli principle. This means that the unit is capable of creating a reduced pressure in the narrowing section of one medium, which, in turn, will cause suction into the flow of another medium. Thus, it is transferred, and then removed from the place of absorption of the first medium.
General information about the device
An ejector is a small but very efficient device that works in tandem with a pump. If we talk about water, then, of course, a water pump is used, however, it can also work in steam, and with steam-oil, and with mercury vapor, and with liquid-mercury.
The use of this equipment is advisable if the aquifer is deep enough. In such situations, it most often happens that conventional pumping equipment cannot cope with providing the house with water, or it delivers too little pressure. The ejector will help solve this problem.
Views
An ejector is a fairly common equipment, and therefore there are several different types of this device:
- The first is the steam room. It is intended for suction of gases and confined spaces, as well as for maintaining a vacuum in these spaces. The use of these units is common in a variety of technical industries.
- The second is a steam jet. This apparatus uses the energy of a jet of steam, with the help of which it is able to suck out liquid, steam or gas from an enclosed space. The steam that exits the nozzle at high speed entails the material being transported. Most often used on various ships and ships for quick suction of water.
- A gas ejector is a device whose principle of operation is based on the fact that the overpressure of high-pressure gases is used to compress low-pressure gases.
Water suction ejector
If we talk about water extraction, then an ejector for a water pump is most often used here. The fact is that if after the water turns out to be lower than seven meters, then an ordinary water pump will cope with great difficulty. Of course, you can buy a submersible pump right away, the performance of which is much higher, but it is expensive. But with the help of an ejector, you can increase the power of an existing unit.
It should be noted that the design of this device is quite simple. Making a homemade gadget also remains a very real challenge. But for this you have to work hard on the drawings for the ejector. The basic principle of operation of this simple apparatus is that it gives additional acceleration to the flow of water, which leads to an increase in the supply of fluid per unit of time. In other words, the task of the unit is to increase the water pressure.
Components
Installing an ejector will result in a dramatic increase in the optimum water intake. Indicators will be approximately equal to 20 to 40 meters in depth. Another of the advantages of this particular device is that its operation requires much less electricity than would require, for example, a more efficient pump.
The pump ejector itself consists of parts such as:
- suction chamber;
- diffuser;
- tapered nozzle.
Principle of operation
The principle of operation of the ejector is completely based on the Bernoulli principle. This statement says that if you increase the speed of movement of any flow, then an area with low pressure will always form around it. Because of this, such an effect as discharging is achieved. The liquid itself will pass through the nozzle. The diameter of this part is always smaller than the dimensions of the rest of the structure.
It is important to understand here that even a slight restriction will significantly accelerate the flow of incoming water. Further, the water will enter the mixer chamber, where it will create a reduced pressure. Due to the occurrence of this process, it will happen so that liquid will enter the mixer through the suction chamber, the pressure of which will be much higher. This is the principle of the ejector, in a nutshell.
It is important to note here that water should not enter the device from a direct source, but from the pump itself. In other words, the unit must be mounted in such a way that some of the water that rises with the pump remains in the ejector itself, passing through the nozzle. This is necessary in order to be able to supply constant kinetic energy to the mass of liquid that needs to be lifted.
By working in this way, a constant acceleration of the flow of matter will be maintained. Of the advantages, one can single out the fact that the use of an ejector for the pump will save a large amount of electricity, since the station will not work at its limit.
Pump device type
Depending on the location, it can be built-in or remote type. There is no huge structural difference between the installation sites, however, some small differences will still make themselves felt, since the installation of the station itself, as well as its performance, will change slightly. Of course, it is clear from the name that built-in ejectors are installed inside the station itself or in the immediate vicinity of it.
This type of unit is good in that you do not have to allocate additional space for its installation. The installation of the ejector itself also does not have to be carried out, since it is already built-in, it will only be necessary to install the station itself. Another advantage of such a device is that it will be very well protected from various kinds of contamination. The disadvantage is that this type of device will create a lot of noise.
Comparison of models
Remote equipment will be somewhat more difficult to install and you will have to allocate a separate place for its location, however, the amount of noise, for example, will be significantly reduced. But there are other disadvantages. Remote models are capable of providing effective work only at a depth of 10 meters. Built-in models are initially designed for not too deep sources, but the advantage is that they create a fairly powerful head, which leads to more efficient use of fluid.
The created jet is quite enough not only for domestic needs, but also for such operations as watering, for example. The increased noise level from the built-in model is one of the most significant problems that will have to be taken care of. Most often, it is solved by the fact that it is installed together with the ejector in a separate building or in the caisson of the well. You will also have to attend to a more powerful electric motor for such stations.
Connection
If we talk about connecting an external ejector, then you will have to perform the following operations:
- Additional pipe laying. This object is necessary in order to ensure the circulation of water from the pressure line to the water intake installation.
- The second step is to connect a special pipe to the suction port of the water intake station.
But the connection of the built-in unit will be no different from the usual installation process of the pumping station. All the necessary procedures for connecting the required pipes or nozzles are carried out at the factory.
Ejector - what is it and how does it work? Any hydraulic engineer who understands the essence of converting the energy of an admixed jet into pressure in a pipeline knows the exact answer to this question. For those uninitiated in the intricacies of engineering, consumers of water from a well understand the fact that this unit of pressure equipment allows the pump to pump water from depths of more than 15-20 meters. But if you want to assemble an ejector with your own hands, improving your pump, then you will need an understanding of the essence of this device, in fact, at an engineering level. And this article will help you understand what an ejector is, how it works and how to assemble such a unit on your own.
What is an ejector and how does it work?
From the point of view of the physics of the process, an ejector is a typical ejector that builds up pressure in a pipeline channel. It works in tandem with a suction pump that takes water from a well or well.
The essence of the work of this unit is to throw a stream of liquid into the pipeline or the working chamber of the pump, accelerated to a high speed. Moreover, the acceleration is carried out by passing through a smoothly tapering section. Due to the difference in the velocities of the main flow and the mixed jet, a vacuum region is created in the unit chamber, which increases the suction force in the pipeline.
Air ejector, liquid medium ejector, and gas-liquid unit work according to this principle. In physics, the mechanics of the operation of such units is described by Bernoulli's law, formulated in the 18th century. However, the first working ejector was assembled only in the 19th century, more precisely in 1858.
Ejector pump - principle of operation and expected benefits
Modern ejectors accelerate the pressure in the pipeline, consuming about 12 percent of the pumped flow volume. That is, if 1000 liters per hour flows through the pipe, then for the efficient operation of the ejector, an emission of 120 l / h will be required.
The pump supports the following principle of operation of the ejector:
- A branch is cut into the pipe behind the pump.
- Water from this outlet is fed to the circulation pipe of the ejector.
- The suction pipe of the ejector is connected to a pipe lowered into the well, and the discharge pipe is connected to the inlet to the pump working chamber.
- A check valve must be installed on the pipe lowered into the well, which blocks the downward movement of water.
- The flow supplied to the circulation pipe moves at a high speed, creating a vacuum in the suction zone of the ejector. Under the influence of this vacuum, the suction force (water rise) and the pressure in the pipeline connected to the pump increase.
The pump equipped with an ejector begins to take water from a well more than 7-8 meters deep. Without an ejector, this process is impossible in principle. Deprived of this unit, a suction-type unit is capable of lifting water only to depths of 5-7 meters. And the ejector pump pumps water even from a depth of 45 meters. Moreover, the efficiency of such pressure equipment depends on the types of ejectors used.
Varieties of ejectors - classification by location
The ejector, the principle of which we described above, is mounted only on surface pumps. Moreover, there are two installation schemes:
- Internal placement is when the ejector is built into the pump casing or somewhere nearby.
- External placement - in this case, the ejector is mounted in a well, where, in addition to the main pipeline, there is also a circulation branch.
The internal ejector for the pump gives a 100% guarantee for the safe operation of the ejector. In this case, it is protected from silting and mechanical damage. In addition, the internal installation reduces the length of the circulation piping. The biggest drawback of this scheme is a slight increase in the suction depth. An internal ejector - what it is and what benefits it gives, we have already explained above - allows the surface pump to pump water only from a depth of 9-10 meters. You can not even dream of 15-40 meters here. And you will also be haunted by the noise of the water beating, propagated by the body of the built-in equipment.
An external ejector for promises such benefits as virtually silent operation (the source of the beat is in the well) and the generation of a significant vacuum, sufficient to lift water from a well up to 45 meters deep. The annoying disadvantages of this scheme include, firstly, the drop in the efficiency of the pressure equipment by about a third, and secondly, the need to install primary filters that regulate the flow frequency (such a unit is afraid of siltation).
However, if you are going to design an ejector with your own hands, then the most affordable option will be the external unit. This is what we will consider below in the text.
Self-production: step by step instructions
If you decide to make an ejector with your own hands, you will not need drawings, since a simplified model of an external unit can be assembled from standard tees, unions and fittings and corners for a water supply system. Moreover, only two adjustable wrenches can be used as working tools, and from consumables only FUM tape will be useful to you.
A complete list of parts for a homemade ejector is as follows:
- Male threaded connection and hose brush for mounting hoses. It will act as a nozzle from which a high-speed stream of water is ejected.
- A tee with an internal thread, the diameter of which must match the external thread of the fitting. This element will be used as a body.
- Three corners with threaded and collet ends. They can be used to streamline the routing of the circulation, suction and discharge pipelines.
- Two or three push-in or crimp fittings used to connect the pipes. Moreover, the latter option requires the use of an additional tool - a crimp wrench
The assembly process itself begins with the preparation of the fitting. A hexagon is grinded off from it, protruding above the threaded end. Next, the processed fitting is screwed into the tee from the side of the through channel, obtaining the basis for the circulation pipe. In this case, the end with a brush (fitting) should not go beyond the boundaries of the tee. If this happens, then it will have to be cut down.
To complete the installation of the circulation pipe in the tee, after the fitting, screw a corner bend with threaded ends, after which another corner is screwed onto the free part of this element, obtaining a U-shaped loop with a fitting ending. It is to this fitting that the circulation pipe from the pump will be attached.
The next step is to prepare the discharge end. To do this, a fitting with an external threaded end and a collet is screwed into the free through end of the tee (it is located above the equipped circulation outlet). The pipe from the ejector to the pump will be attached to this collet.
The last stage is the arrangement of the suction end. In this case, we simply screw a fitting-angle with an external thread and a collet clamp on the other end into the side outlet of the tee. Moreover, the collet should look down towards the circulation pipe. And the suction pipe will be attached to this fitting, laid down to the bottom of the well.
Success secrets - how to improve the efficiency of a homemade design
Firstly, the diameter of the circulation pipe should be half the size of the pressure head and suction line. Thanks to this, the flow will receive a high speed even on the approach to the fitting that replaced the nozzle.
Secondly, it is better not to lower the suction pipe to the very bottom of the well - it should be located at least one meter away. And even better - at a distance of 1.5 meters from the bottom. So silting can be avoided.
Thirdly, a check valve must be screwed onto the end of the suction pipe, which cuts off the drainage of water downward, and it will be useful to put a coarse mesh filter behind the valve. This increases the efficiency of the ejectors and reduces the risk of silting up the structure.
