Energy saving in heat supply systems

Completed by: students of group T-23

Salazhenkov M.Yu.

Krasnov D.

Introduction

Today, the energy saving policy is a priority direction in the development of energy and heat supply systems. In fact, every state enterprise draws up, approves and implements plans for energy saving and energy efficiency improvement of enterprises, workshops, etc.

The country's heating system is no exception. It is quite large and cumbersome, consumes colossal amounts of energy and at the same time there are no less colossal losses of heat and energy.

Let's consider what the heat supply system is, where the greatest losses occur and what complexes of energy-saving measures can be applied to increase the "efficiency" of this system.

Heating systems

Heat supply - supply of heat to residential, public and industrial buildings (structures) to meet household (heating, ventilation, hot water supply) and technological needs of consumers.

In most cases, heat supply is the creation of a comfortable indoor environment - at home, at work or in a public place. Heating supply also includes heating tap water and water in swimming pools, greenhouse heating, etc.

The distance over which heat is transported in modern district heating systems reaches several tens of kilometers. The development of heat supply systems is characterized by an increase in the power of the heat source and unit capacities of the installed equipment. Thermal power of modern thermal power plants reaches 2-4 Tkal/h, regional boiler houses 300-500 Gkal/h. In some heat supply systems, several heat sources work together for common heat networks, which increases the reliability, flexibility and efficiency of heat supply.

The water heated in the boiler room can circulate directly to the heating system. Hot water is heated in the heat exchanger of the hot water supply system (DHW) to a lower temperature, about 50-60 ° C. The return water temperature can be an important factor in boiler protection. The heat exchanger not only transfers heat from one circuit to another, but also effectively copes with the pressure difference that exists between the first and second circuits.

The required floor heating temperature (30 °C) can be obtained by adjusting the temperature of the circulating hot water. The temperature difference can also be achieved by using three-way valve, mixing in the system hot water with return.

Regulation of heat supply in heat supply systems (daily, seasonal) is carried out both in the heat source and in heat-consuming installations. In water heating systems, the so-called central quality control of heat supply is usually carried out for the main type of heat load - heating or for a combination of two types of load - heating and hot water supply. It consists in changing the temperature of the heat carrier supplied from the heat supply source to the heat network in accordance with the accepted temperature schedule (that is, the dependence of the required water temperature in the network on the outside air temperature). Central qualitative regulation is supplemented by local quantitative regulation in heating points; the latter is most common in hot water applications and is usually carried out automatically. In steam heating systems, local quantitative regulation is mainly carried out; the steam pressure in the heat supply source is maintained constant, the steam flow is regulated by consumers.

1.1 Composition of the heating system

The heat supply system consists of the following functional parts:

1) source of heat energy production (boiler house, thermal power plant, solar collector, devices for the utilization of industrial heat waste, installations for the use of heat from geothermal sources);

2) transporting devices of thermal energy to the premises (heating networks);

3) heat-consuming devices that transmit thermal energy consumer (heating radiators, heaters).

1.2 Classification of heating systems

According to the place of heat generation, heat supply systems are divided into:

1) centralized (the source of heat energy production works for the heat supply of a group of buildings and is connected by transport devices with heat consumption devices);

2) local (the consumer and the source of heat supply are located in the same room or in close proximity).

The main advantages of district heating over local heating are a significant reduction in fuel consumption and operating costs (for example, by automating boiler plants and increasing their efficiency); the possibility of using low-grade fuel; reducing the degree of air pollution and improving the sanitary condition of populated areas. In local heating systems, heat sources are furnaces, hot water boilers, water heaters (including solar ones), etc.

According to the type of heat carrier, heat supply systems are divided into:

1) water (with temperature up to 150 °C);

2) steam (pressure 7-16 atm).

Water serves mainly to cover domestic, and steam - technological loads. The choice of temperature and pressure in heat supply systems is determined by the requirements of consumers and economic considerations. With an increase in the distance of heat transportation, an economically justified increase in the parameters of the coolant increases.

According to the method of connecting the heating system to the heat supply system, the latter are divided into:

1) dependent (the heat carrier heated in the heat generator and transported through heat networks enters directly into heat-consuming devices);

2) independent (the heat carrier circulating through the heating networks heats the heat carrier circulating in the heating system in the heat exchanger). (Fig.1)

In independent systems, consumer installations are hydraulically isolated from the heating network. Such systems are used mainly in large cities - in order to increase the reliability of heat supply, as well as in cases where the pressure regime in the heat network is unacceptable for heat-consuming installations due to their strength or when the static pressure created by the latter is unacceptable for the heat network ( such are, for example, the heating systems of high-rise buildings).

Figure 1 - Schematic diagrams of heat supply systems according to the method of connecting heating systems to them

According to the method of connecting the hot water supply system to the heat supply system:

1) closed;

2) open.

In closed systems, hot water supply is supplied with water from the water supply, heated to the required temperature by water from the heating network in heat exchangers installed in heating points. In open systems, water is supplied directly from the heating network (direct water intake). Water leakage due to leaks in the system, as well as its consumption for water intake, are compensated by additional supply of an appropriate amount of water to the heating network. To prevent corrosion and scale formation on the inner surface of the pipeline, the water supplied to the heating network undergoes water treatment and deaeration. In open systems, the water must also meet the requirements for drinking water. The choice of system is determined mainly by the presence of a sufficient amount of water of drinking quality, its corrosive and scale-forming properties. Both types of systems have become widespread in Ukraine.

According to the number of pipelines used to transfer the coolant, heat supply systems are distinguished:

single-pipe;

two-pipe;

multipipe.

Single-pipe systems are used in cases where the coolant is completely used by consumers and is not returned back (for example, in steam systems without condensate return and in open water systems, where all the water coming from the source is disassembled for hot water supply to consumers).

In two-pipe systems, the heat carrier is fully or partially returned to the heat source, where it is heated and replenished.

Multi-pipe systems suit, if necessary, the allocation of certain types of heat load (for example, hot water supply), which simplifies the regulation of heat supply, operation mode and methods of connecting consumers to heating networks. In Russia, two-pipe heat supply systems are predominantly used.

1.3 Types of heat consumers

The heat consumers of the heat supply system are:

1) heat-using sanitary systems of buildings (systems of heating, ventilation, air conditioning, hot water supply);

2) technological installations.

The use of hot water for space heating is quite common. At the same time, a variety of methods for transferring water energy are used to create a comfortable indoor environment. One of the most common is the use of heating radiators.

An alternative to heating radiators is floor heating, when the heating circuits are located under the floor. The floor heating circuit is usually connected to the heating radiator circuit.

Ventilation - a fan coil unit that supplies hot air to a room, usually used in public buildings. Often a combination of heating devices is used, for example, radiators for heating and underfloor heating or radiators for heating and ventilation.

Hot tap water has become part of everyday life and daily needs. Therefore, a hot water installation must be reliable, hygienic and economical.

According to the mode of heat consumption during the year, two groups of consumers are distinguished:

1) seasonal, requiring heat only during the cold season (for example, heating systems);

2) year-round, requiring heat all year round (hot water supply systems).

Depending on the ratio and modes of individual types of heat consumption, three characteristic groups of consumers are distinguished:

1) residential buildings (characterized by seasonal heat consumption for heating and ventilation and year-round - for hot water supply);

2) public buildings (seasonal heat consumption for heating, ventilation and air conditioning);

3) industrial buildings and structures, including agricultural complexes (all types of heat consumption, the quantitative ratio between which is determined by the type of production).

2 District heating

District heating is an environmentally friendly and reliable way to provide heat. District heating systems distribute hot water or, in some cases, steam from a central boiler plant between multiple buildings. There is a very wide range of sources that serve to generate heat, including the burning of oil and natural gas or the use of geothermal waters. The use of heat from low temperature sources, such as geothermal heat, is possible with the use of heat exchangers and heat pumps. The possibility of using non-utilized heat from industrial enterprises, surplus heat from waste processing, industrial processes and sewerage, targeted heating plants or thermal power plants in district heating, makes it possible to implement optimal choice heat source in terms and energy efficiency. This way you optimize costs and protect the environment.

Hot water from the boiler house is fed to a heat exchanger that separates the production site from the distribution pipelines of the district heating network. The heat is then distributed to the final consumers and fed through the substations to the respective buildings. Each of these substations usually includes one heat exchanger for space heating and hot water.

There are several reasons for installing heat exchangers to separate a heating plant from a district heating network. Where significant pressure and temperature differences exist that can cause serious damage to equipment and property, a heat exchanger can keep sensitive heating and ventilation equipment from entering contaminated or corrosive media. Another important reason for separating the boiler house, distribution network and end users is to clearly define the functions of each component of the system.

In a combined heat and power plant (CHP), heat and electricity are produced simultaneously, with heat being the by-product. Heat is usually used in district heating systems, leading to increased energy efficiency and cost savings. The degree of use of energy obtained from fuel combustion will be 85–90%. The efficiency will be 35–40% higher than in the case of separate production of heat and electricity.

In CHP plants, fuel combustion heats water, which turns into steam at high pressure and high temperature. The steam drives a turbine connected to a generator that produces electricity. After the turbine, the steam is condensed in a heat exchanger. The heat released during this process is then fed into the district heating pipes and distributed to the final consumers.

For the end consumer, district heating means uninterrupted energy supply. A district heating system is more convenient and efficient than small individual home heating systems. Modern technologies fuel combustion and emission cleaning reduce negative impact on the environment.

In apartment buildings or other buildings heated by district heating, the main requirement is heating, hot water supply, ventilation and floor heating for a large number of consumers with minimal cost energy. Using high-quality equipment in the heating system, you can reduce overall costs.

Another very important task of heat exchangers in district heating is to ensure the safety of the internal system by separating end users from the distribution network. This is necessary because of the significant difference in temperature and pressure values. In the event of an accident, the risk of flooding can also be minimized.

In central heating points, a two-stage scheme for connecting heat exchangers is often found (Fig. 2, A). This connection means maximum heat utilization and low return water temperature when using the hot water system. It is particularly advantageous in combined heat and power plant applications where a low return water temperature is desirable. This type of substation can easily supply heat to up to 500 apartments, and sometimes more.

A) Two-stage connection B) Parallel connection

Figure 2 - Scheme of connecting heat exchangers

Parallel connection of a DHW heat exchanger (Fig.2, B) is less complicated than a two-stage connection and can be applied to any size plant that does not need a low return water temperature. Such a connection is usually used for small and medium-sized heating points with a load of up to approximately 120 kW. Connection diagram for hot water heaters in accordance with SP 41-101-95.

Most district heating systems place high demands on the installed equipment. The equipment must be reliable and flexible, providing the necessary safety. In some systems, it must also meet very high hygiene standards. Another important factor in most systems is low operating costs.

However, in our country, the district heating system is in a deplorable state:

technical equipment and the level of technological solutions in the construction of heat networks correspond to the state of the 1960s, while the radii of heat supply have sharply increased, and there has been a transition to new standard sizes of pipe diameters;

the quality of metal of heat pipelines, thermal insulation, shut-off and control valves, construction and laying of heat pipelines are significantly inferior to foreign analogues, which leads to large losses of thermal energy in networks;

poor conditions for thermal and waterproofing of heat pipelines and channels of heat networks contributed to an increase in the damage of underground heat pipelines, which led to serious problems replacement of heating network equipment;

domestic equipment of large CHPPs corresponds to the average foreign level of the 1980s, and at present, steam turbine CHPPs are characterized by a high accident rate, since almost half of the installed capacity of the turbines has exhausted the estimated resource;

operating coal-fired CHP plants do not have flue gas purification systems from NOx and SOx, and the efficiency of trapping particulate matter often does not reach the required values;

The competitiveness of DH at the present stage can only be ensured by the introduction of specially new technical solutions, both in terms of the structure of systems, and in terms of schemes, equipment of energy sources and heating networks.

2.2 Efficiency of district heating systems

One of the most important conditions for the normal operation of the heat supply system is the creation of a hydraulic regime that provides pressure in the heat network sufficient to create network water flows in heat-consuming installations in accordance with a given heat load. The normal operation of heat consumption systems is the essence of providing consumers with thermal energy of the appropriate quality, and consists for the energy supply organization in maintaining the parameters of the heat supply mode at the level regulated by the Rules for Technical Operation (PTE) of power plants and networks of the Russian Federation, PTE of thermal power plants. The hydraulic regime is determined by the characteristics of the main elements of the heat supply system.

During operation in the existing district heating system due to a change in the nature of the heat load, the connection of new heat consumers, an increase in the roughness of pipelines, adjustments of the calculated temperature for heating, changes temperature graph release of thermal energy (TE) from the source of TE, as a rule, there is an uneven supply of heat to consumers, an overestimation of the flow of network water and a reduction in the throughput of pipelines.

In addition to this, as a rule, there are problems in the heating systems. Such as, misregulation of heat consumption modes, understaffing of elevator units, unauthorized violation by consumers of connection schemes (established by projects, specifications and agreements). These problems of heat consumption systems are manifested, first of all, in the misregulation of the entire system, which is characterized by increased coolant flow rates. As a result, insufficient (due to increased pressure losses) available pressures of the coolant at the inlets, which in turn leads to the desire of subscribers to provide the necessary drop by draining network water from the return pipelines to create at least a minimum circulation in heating appliances (violations of connection schemes and etc.), which leads to an additional increase in flow and, consequently, to additional pressure losses, and to the emergence of new subscribers with reduced pressure drops, etc. There is a "chain reaction" in the direction of a total misalignment of the system.

All this has a negative impact on the entire heat supply system and on the activities of the energy supply organization: the inability to comply with the temperature schedule; increased replenishment of the heat supply system, and when the water treatment capacity is exhausted, forced replenishment with raw water (consequence - internal corrosion, premature failure of pipelines and equipment); forced increase in heat supply to reduce the number of complaints from the population; increase in operating costs in the system of transport and distribution of thermal energy.

It should be pointed out that in the heat supply system there is always an interrelation of the steady thermal and hydraulic regimes. A change in the flow distribution (including its absolute value) always changes the heat exchange condition, both directly at the heating installations and in heat consumption systems. The result of abnormal operation of the heating system is, as a rule, a high temperature of the return network water.

It should be noted that the temperature of the return network water at the source of thermal energy is one of the main operational characteristics designed to analyze the state of the equipment of thermal networks and the modes of operation of the heat supply system, as well as to assess the effectiveness of measures taken by organizations operating thermal networks in order to increase the level operation of the heating system. As a rule, in the case of misalignment of the heat supply system, the actual value of this temperature differs significantly from its normative, calculated value for this heat supply system.

Thus, when the heat supply system is misaligned, the temperature of the network water, as one of the main indicators of the mode of supply and consumption of thermal energy in the heat supply system, turns out to be: in the supply pipeline, almost in all intervals of the heating season, it is characterized reduced values; the temperature of the return network water, despite this, is characterized by increased values; the temperature difference in the supply and return pipelines, namely this indicator (along with the specific consumption of network water per connected heat load) characterizes the level of quality of heat energy consumption, is underestimated compared to the required values.

It should be noted one more aspect related to the increase relative to the calculated value of network water consumption for the thermal regime of heat consumption systems (heating, ventilation). For direct analysis, it is advisable to use the dependence that determines, in case of deviation of the actual parameters and structural elements of the heat supply system from the calculated ones, the ratio of the actual heat energy consumption in heat consumption systems to its calculated value.

where Q is the consumption of thermal energy in heat consumption systems;

g - consumption of network water;

tp and tо - temperature in the supply and return pipelines.

This dependence (*) is shown in Fig.3. The ordinate shows the ratio of the actual consumption of thermal energy to its calculated value, the abscissa shows the ratio of the actual consumption of network water to its calculated value.

Figure 3 - Graph of the dependence of the consumption of thermal energy by systems

heat consumption from the consumption of network water.

As general trends, it is necessary to point out that, firstly, an increase in network water consumption by n times does not cause an increase in thermal energy consumption corresponding to this number, that is, the heat consumption coefficient lags behind the network water consumption coefficient. Secondly, with a decrease in the consumption of network water, the supply of heat to the local heat consumption system decreases the faster, the lower the actual consumption of network water compared to the calculated one.

Thus, heating and ventilation systems react very poorly to excessive consumption of network water. Thus, an increase in the consumption of network water for these systems by 50% relative to the calculated value causes an increase in heat consumption by only 10%.

The point in Fig. 3 with coordinates (1; 1) displays the calculated, actually achievable mode of operation of the heat supply system after commissioning. Under the actually achievable mode of operation is meant such a mode, which is characterized by the existing position of the structural elements of the heat supply system, heat losses by buildings and structures and determined by the total consumption of network water at the outlets of the heat source, necessary to provide a given heat load with the existing heat supply schedule.

It should also be noted that the increased consumption of network water, due to the limited value of the throughput of heat networks, leads to a decrease in the values ​​of available pressures at the consumer inlets necessary for the normal operation of heat-consuming equipment. It should be noted that the pressure loss in the heating network is determined by a quadratic dependence on the network water flow:

That is, with an increase in the actual consumption of network water GF by 2 times relative to the calculated value GP, the pressure losses in the heating network increase by 4 times, which can lead to unacceptably small available pressures at the thermal nodes of consumers and, consequently, to insufficient heat supply to these consumers, which can cause unauthorized discharge of network water to create circulation (unauthorized violation by consumers of connection schemes, etc.)

Further development of such a heat supply system along the path of increasing the flow rate of the coolant, firstly, will require the replacement of the head sections of the heat pipelines, the additional installation of network pumping units, an increase in the productivity of water treatment, etc., and secondly, it leads to an even greater increase in additional costs - the cost of compensation for electricity, make-up water, heat losses.

Thus, it seems technically and economically more reasonable to develop such a system by improving its quality indicators - increasing the temperature of the coolant, pressure drops, increasing the temperature difference (heat removal), which is impossible without a drastic reduction in coolant consumption (circulation and make-up) in heat consumption systems and , respectively, in the entire heating system.

Thus, the main measure that can be proposed to optimize such a heat supply system is the adjustment of the hydraulic and thermal regime of the heat supply system. The technical essence of this measure is to establish the flow distribution in the heat supply system based on the calculated (i.e., corresponding to the connected heat load and the selected temperature schedule) network water consumption for each heat consumption system. This is achieved by installing appropriate throttling devices (autoregulators, throttle washers, elevator nozzles) at the inputs to the heat consumption systems, the calculation of which is based on the calculated pressure drop at each input, which is calculated based on the hydraulic and thermal calculation of the entire heat supply system.

It should be noted that the creation of a normal mode of operation of such a heat supply system is not limited to carrying out adjustment activities, it is also necessary to carry out work to optimize the hydraulic mode of the heat supply system.

Regime adjustment covers the main links of the district heating system: a water heating installation of a heat source, central heating points (if any), a heat network, control and distribution points (if any), individual heating points and local heat consumption systems.

Commissioning begins with an inspection of the district heating system. The collection and analysis of initial data on the actual operating modes of the system of transport and distribution of heat energy, information on the technical condition of heat networks, the degree of equipment of the heat source, heat networks and subscribers with commercial and technological measuring instruments is carried out. The applied modes of heat energy supply are analyzed, possible defects in the design and installation are identified, information is selected to analyze the characteristics of the system. An analysis is made of operational (statistical) information (sheets of accounting for coolant parameters, energy supply and consumption modes, actual hydraulic and thermal modes of heating networks) with different values outside air temperature in the base periods, obtained according to the readings of standard measuring instruments, as well as an analysis of the reports of specialized organizations.

At the same time, a design scheme for heat networks is being developed. A mathematical model of the heat supply system is being created on the basis of the ZuluThermo calculation complex, developed by Politerm (St. Petersburg), capable of simulating the actual thermal and hydraulic operation of the heat supply system.

It should be pointed out that there is a fairly common approach, which consists in minimizing the financial costs associated with the development of measures to adjust and optimize the heat supply system, namely, the costs are limited to the acquisition of a specialized software package.

The "pitfall" in this approach is the reliability of the original data. The mathematical model of the heat supply system, created on the basis of unreliable initial data on the characteristics of the main elements of the heat supply system, turns out, as a rule, to be inadequate to reality.

2.3 Energy saving in DH systems

Recently, there have been criticisms of district heating based on district heating - the joint generation of heat and electrical energy. As the main disadvantages, there are large heat losses in pipelines during heat transport, a decrease in the quality of heat supply due to non-compliance with the temperature schedule and the required pressure from consumers. It is proposed to switch to decentralized, autonomous heat supply from automated boiler houses, including those located on the roofs of buildings, justifying this with lower cost and no need to lay heat pipes. But at the same time, as a rule, it is not taken into account that the connection of the heat load to the boiler room makes it impossible to generate cheap electricity for heat consumption. Therefore, this part of the ungenerated electricity should be replaced by its production by the condensation cycle, the efficiency of which is 2-2.5 times lower than that of the heating cycle. Consequently, the cost of electricity consumed by the building, the heat supply of which is carried out from the boiler house, should be higher than that of the building connected to the heating system of heat supply, and this will cause a sharp increase in operating costs.

S. A. Chistovich anniversary conference"75 Years of District Heating in Russia", held in Moscow in November 1999, proposed that home boilers supplement district heating, acting as peak heat sources, where the missing network capacity does not allow high-quality heat supply to consumers. At the same time, heat supply is preserved and the quality of heat supply is improved, but this decision reeks of stagnation and hopelessness. It is necessary that the district heating supply fully performs its functions. After all, district heating has its own powerful peak boiler houses, and it is obvious that one such boiler house will be more economical than hundreds of small ones, and if the capacity of the networks is insufficient, then it is necessary to shift the networks or cut off this load from the networks so that it does not violate the quality of heat supply to other consumers.

Great success in district heating has been achieved by Denmark, which, despite the low concentration of heat load per 1 m2 of surface area, is ahead of us in terms of district heating coverage per capita. Denmark is holding a special public policy by preference for connecting new heat consumers to district heating. In Western Germany, for example, in Mannheim, district heating based on district heating is developing rapidly. In the Eastern lands, where, focusing on our country, heat supply was also widely used, despite the rejection of panel housing construction, central heating in residential areas, which turned out to be inefficient in a market economy and Western image life, continues to develop the area of ​​district heating based on district heating as the most environmentally friendly and cost-effective.

All of the above indicates that at the new stage we must not lose our leading positions in the field of district heating, and for this it is necessary to modernize the district heating system in order to increase its attractiveness and efficiency.

All the advantages of the joint generation of heat and electricity were attributed to the side of electricity, district heating was financed on a residual basis - sometimes the CHP had already been built, but the heating networks had not yet been brought up. As a result, low-quality heat pipelines with poor insulation and inefficient drainage were created, heat consumers were connected to heat networks without automatic load control, at best, using hydraulic regulators for stabilizing the coolant flow of very poor quality.

This forced the supply of heat from the source according to the method of central quality control (by changing the temperature of the coolant depending on the outside temperature according to a single schedule for all consumers with constant circulation in the networks), which led to a significant overconsumption of heat by consumers due to differences in their operating mode and the impossibility of joint operation of several heat sources on a single network for mutual redundancy. The absence or inefficiency of the operation of control devices at the points of connection of consumers to heating networks also caused an overrun of the volume of the coolant. This led to an increase in the return water temperature to such an extent that there was a danger of failure of the station circulation pumps, and this forced the reduction of heat supply at the source, violating the temperature schedule even under conditions of sufficient power.

Unlike us, in Denmark, for example, all the benefits of district heating in the first 12 years are given to the side of thermal energy, and then they are divided in half with electrical energy. As a result, Denmark was the first country to manufacture pre-insulated pipes for ductless installation with a hermetic cover layer and an automatic leak detection system, which dramatically reduced heat loss during transportation. In Denmark, for the first time, silent, supportless "wet-running" circulation pumps, heat metering devices and effective systems for auto-regulating the heat load were invented, which made it possible to build automated individual heating points (ITP) directly in the buildings of consumers with automatic control of the supply and metering of heat in places of its use.

Total automation of all heat consumers made it possible to: abandon the qualitative method central regulation on a heat source that causes undesirable temperature fluctuations in the pipelines of the heating network; reduce the maximum water temperature parameters to 110-1200C; ensure the possibility of operation of several heat sources, including waste incinerators, on a single network with the most efficient use of each.

The temperature of the water in the supply pipeline of heating networks varies depending on the level of the established outdoor temperature in three steps: 120-100-80°C or 100-85-70°C (there is a tendency to an even greater decrease in this temperature). And inside each stage, depending on the change in load or deviation of the outside temperature, the flow rate of the coolant circulating in the heating networks changes according to the signal of the fixed value of the pressure difference between the supply and return pipelines - if the pressure difference drops below the set value, then the subsequent heat generating and pumping stations are switched on installation. Heat supply companies guarantee each consumer a specified minimum level of pressure drop in the supply networks.

Consumers are connected through heat exchangers, and, in our opinion, an excessive number of connection steps are used, which is apparently caused by the boundaries of property ownership. Thus, the following connection scheme was demonstrated: to the main networks with design parameters of 125 ° C, which are administered by the energy producer, through a heat exchanger, after which the water temperature in the supply pipeline drops to 120 ° C, distribution networks are connected, which are in municipal ownership.

The level of maintenance of this temperature is set electronic regulator acting on the valve installed on the return pipeline of the primary circuit. In the secondary circuit, the coolant is circulated by pumps. Connection to these distributing networks of local heating and hot water supply systems of individual buildings is carried out through independent heat exchangers installed in the basements of these buildings with a full range of heat control and metering devices. Moreover, the regulation of the temperature of the water circulating in the local heating system is carried out according to the schedule, depending on the change in the temperature of the outside air. Under design conditions, the maximum water temperature reaches 95°C, recently there has been a tendency to decrease it to 75-70°C, the maximum return water temperature is 70 and 50°C, respectively.

Connection of heating substations of individual buildings is carried out according to standard schemes with parallel connection of a hot water storage tank or in a two-stage scheme using the potential of the heat carrier from the return pipe after the heating water heater using high-speed hot water heat exchangers, while it is possible to use a hot water pressure storage tank with a tank charging pump. In the heating circuit, pressurized membrane tanks are used to collect water when it expands from heating; in our case, atmospheric expansion tanks installed at the top of the system are more used.

To stabilize the operation of the control valves at the inlet to the heating point, a hydraulic regulator for the constancy of the pressure difference is usually installed. And in order to bring the heating systems with pump circulation to the optimal operating mode and facilitate the distribution of the coolant along the risers of the system, a "partner valve" in the form of a balance valve, which allows, according to the pressure loss measured on it, to set the correct flow rate of the circulating coolant.

In Denmark, they do not pay much attention to the increase in the calculated flow rate of the heat carrier at the heating point when turning on the heating of water for domestic needs. In Germany, it is forbidden by law to take into account the load on hot water supply when selecting heat power, and when automating heating points, it is accepted that when the hot water heater is turned on and when the storage tank is filled, the pumps that circulate in the heating system are turned off, i.e., the heat supply to the heating.

In our country, serious importance is also attached to preventing an increase in the power of the heat source and the estimated flow rate of the heat carrier circulating in the heating network during the hours of the maximum hot water supply. But the solution adopted in Germany for this purpose cannot be applied in our conditions, since we have a much higher load ratio of hot water supply and heating, due to the large absolute consumption of domestic water and higher population density.

Therefore, when automating the heat points of consumers, they apply the limitation of the maximum water flow from the heating network when the specified value is exceeded, determined based on the average hourly load of the hot water supply. When heating residential areas, this is done by closing the valve of the heat supply regulator for heating during the hours of the maximum water consumption. By setting the heating controller to some overestimation of the maintained heat carrier temperature curve, the underheating in the heating system that occurs when the maximum watershed is passed is compensated during drawdown periods below the average (within the specified water flow from the heating network - coupled regulation).

The water flow sensor, which is a signal for limitation, is a water flow meter included in the heat meter kit installed at the heating network inlet to the central heating substation or ITP. The differential pressure regulator at the inlet cannot serve as a flow limiter, since it provides a given differential pressure in conditions of full opening of the valves of the heating and hot water supply regulators installed in parallel.

In order to increase the efficiency of the joint generation of heat and electricity and equalize the maximum energy consumption in Denmark, heat accumulators, which are installed at the source, are widely used. The lower part of the accumulator is connected to the return pipeline of the heating network, the upper part is connected to the supply pipeline through a movable diffuser. With a reduction in circulation in the distribution heating networks, the tank is charged. With an increase in circulation, the excess coolant flow from the return pipeline enters the tank, and hot water is squeezed out of it. The need for heat accumulators increases in CHP plants with backpressure turbines, in which the ratio of generated electrical and thermal energy is fixed.

If the design temperature of the water circulating in the heating networks is below 100 ° C, then atmospheric-type storage tanks are used; at a higher design temperature, pressure is created in the tanks to ensure that hot water does not boil.

However, the installation of thermostats together with heat flow meters for each heating device leads to an almost double increase in the cost of the heating system, and in a single-pipe scheme, in addition, the required heating surface of the devices increases to 15% and there is a significant residual heat transfer of devices in the closed position of the thermostat, which reduces the efficiency of auto-regulation. Therefore, an alternative to such systems, especially in low-cost municipal construction, are façade automatic heating control systems - for extended buildings and central ones with temperature graph correction based on the deviation of air temperature in the prefabricated exhaust ventilation ducts from apartment kitchens - for point buildings or buildings with a complex configuration.

However, it must be borne in mind that when reconstructing existing residential buildings, it is necessary to enter each apartment with welding to install thermostats. At the same time, when organizing front-facing auto-regulation, it is enough to cut jumpers between front-facing branches of sectional heating systems in the basement and in the attic, and for 9-story non-attic buildings of mass construction of the 60-70s - only in the basement.

It should be noted that new construction per year does not exceed 1-2% of the existing housing stock. This indicates the importance of the reconstruction of existing buildings in order to reduce the cost of heat for heating. However, it is impossible to automate all buildings at once, and in conditions where several buildings are automated, real savings are not achieved, since the heat carrier saved at automated facilities is redistributed among non-automated ones. The above once again confirms that it is necessary to build PDCs at existing heat networks at a faster pace, since it is much easier to automate simultaneously all buildings powered by one PDC than from a CHP, and other already created PDCs will not let an excess amount of coolant into their distribution networks.

All of the above does not exclude the possibility of connecting individual buildings to boiler houses with an appropriate feasibility study with an increase in the tariff for consumed electricity (for example, when laying or re-laying a large number of networks is necessary). But in the conditions of the existing system of district heating from CHP, this should have a local character. The possibility of using heat pumps, transferring part of the load to CCGTs and GTUs is not ruled out, but given the current conjuncture of prices for fuel and energy carriers, this is not always profitable.

Heat supply of residential buildings and microdistricts in our country, as a rule, is carried out through group heating points (CHP), after which individual buildings are supplied through independent pipelines with hot water for heating and for domestic needs with tap water heated in heat exchangers installed in the central heating station. Sometimes up to 8 heat pipelines come out of the central heating center (with a 2-zone hot water supply system and a significant ventilation load), and although galvanized hot water supply pipelines are used, due to the lack of chemical water treatment they are subject to intense corrosion and after 3-5 years of operation on them fistulas appear.

Currently, in connection with the privatization of housing and service enterprises, as well as with the increase in the cost of energy carriers, the transition from group heating points to individual (ITP) located in a heated building is relevant. This makes it possible to use a more efficient system of façade auto-regulation of heating for extended buildings or a central system with correction for the internal air temperature in point buildings, it allows to abandon hot water distribution networks, reducing heat losses during transportation and electricity consumption for domestic hot water pumping. Moreover, it is expedient to do this not only in new construction, but also in the reconstruction of existing buildings. There is such experience in the Eastern lands of Germany, where central heating stations were built in the same way as we did, but now they are left only as pumping water pumping stations (if necessary), and heat exchange equipment, together with circulation pumps, control and metering units, are transferred to the ITP of buildings . Intra-quarter networks are not laid, hot water pipelines are left in the ground, and heating pipelines, as more durable ones, are used to supply superheated water to buildings.

To improve the manageability of heating networks, to which a large number of IHS will be connected, and to ensure the possibility of redundancy in automatic mode it is necessary to return to the device of control and distribution points (CDP) in places where distribution networks are connected to the main ones. Each KRP is connected to the main on both sides of the sectional valves and serves consumers with a thermal load of 50-100 MW. Switching electric valves at the inlet, pressure regulators, circulating-mixing pumps, a temperature regulator, a safety valve, heat and coolant consumption meters, control and telemechanics devices are installed in the KRP.

The automation circuit of the KRP ensures that the pressure is maintained at a constant minimum level in the return line; maintaining a constant predetermined pressure drop in the distribution network; reduction and maintenance of water temperature in the supply pipeline of the distribution network according to a given schedule. As a result, in the backup mode, it is possible to supply a reduced amount of circulating water with an increased temperature through the mains from the CHPP without disturbing the temperature and hydraulic conditions in the distribution networks.

KRP should be located in ground pavilions, they can be blocked with water pumping stations (this will allow in most cases to refuse to install high-pressure, and therefore more noisy pumps in buildings), and can serve as the boundary of the balance belonging of the heat-releasing organization and the heat-distributing one (the next boundary between the heat-distributing and the wall of the building will be the heat-using organization). Moreover, the KRP should be under the jurisdiction of the heat-producing organization, since they serve to control and reserve the main networks and provide the ability to operate several heat sources for these networks, taking into account the maintenance of the coolant parameters specified by the heat-distributing organization at the outlet of the KRP.

Correct use the heat carrier from the side of the heat consumer is provided by the use of efficient systems management automation. Now there are a large number of computer systems that can perform any complexity of control tasks, but technological tasks and circuit solutions for connecting heat consumption systems remain decisive.

Recently, they began to build water heating systems with thermostats, which carry out individual automatic control of the heat transfer of heating devices according to the air temperature in the room where the device is installed. Such systems are widely used abroad, with the addition of mandatory measurement of the amount of heat used by the device as a share of the total heat consumption of the building's heating system.

In our country, in mass construction, such systems began to be used for elevator connection to heating networks. But the elevator is designed in such a way that, with a constant nozzle diameter and the same available pressure, it passes a constant flow rate of the coolant through the nozzle, regardless of the change in the flow rate of water circulating in the heating system. As a result, in 2-pipe heating systems, in which thermostats, when closed, lead to a reduction in the flow rate of the coolant circulating in the system, when connected to an elevator, the water temperature in the supply pipe will increase, and then in the opposite direction, which will lead to an increase in heat transfer from the unregulated part of the system (risers) and to underutilization of the coolant.

In a single-pipe heating system with permanent closing sections, when the thermostats are closed, hot water is discharged into the riser without cooling, which also leads to an increase in the water temperature in the return pipeline and, due to the constancy of the mixing ratio in the elevator, to an increase in the water temperature in the supply pipeline, and therefore to the same consequences as in a 2-pipe system. Therefore, in such systems, it is mandatory to automatically control the temperature of the water in the supply pipeline according to the schedule, depending on the change in the temperature of the outside air. Such regulation is possible by changing the circuit design for connecting the heating system to the heating network: replacing a conventional elevator with an adjustable one, by using pump mixing with a control valve, or by connecting it through a heat exchanger with pump circulation and a control valve on network water in front of the heat exchanger. [

3 DECENTRALIZED HEATING

3.1 Prospects for the development of decentralized heat supply

Previously decisions taken on the closure of small boiler houses (under the pretext of their low efficiency, technical and environmental danger) today turned into over-centralization of heat supply, when hot water passes from the CHP to the consumer, a path of 25-30 km, when the shutdown of the heat source due to non-payments or an emergency leads to freezing cities with millions of people.

Most industrialized countries went the other way: they improved heat-generating equipment, increasing the level of its safety and automation, efficiency gas burner devices, sanitary and hygienic, environmental, ergonomic and aesthetic indicators; created a comprehensive energy accounting system for all consumers; brought the regulatory and technical base in line with the requirements of expediency and convenience of the consumer; optimized the level of heat supply centralization; switched to the widespread introduction of alternative sources of thermal energy. The result of this work was real energy saving in all areas of the economy, including housing and communal services.

A gradual increase in the share of decentralized heat supply, maximum proximity of the heat source to the consumer, accounting by the consumer of all types of energy resources will not only create more comfortable conditions for the consumer, but also ensure real savings gas fuel.

A modern decentralized heat supply system is a complex set of functionally interconnected equipment, including an autonomous heat generating plant and building engineering systems (hot water supply, heating and ventilation systems). The main elements of the apartment heating system, which is a type of decentralized heat supply, in which each apartment in an apartment building is equipped with an autonomous system for providing heat and hot water, are a heating boiler, heating appliances, air supply and combustion products removal systems. The wiring is carried out using a steel pipe or modern heat-conducting systems - plastic or metal-plastic.

Traditional for our country, the system of centralized heat supply through CHPPs and main heat pipelines is known and has a number of advantages. But in the context of the transition to new economic mechanisms, the well-known economic instability and the weakness of interregional, interdepartmental ties, many of the advantages of the district heating system turn into disadvantages.

The main one is the length of heating mains. The average percentage of wear is estimated at 60-70%. The specific damage rate of heat pipelines has now increased to 200 registered damage per year per 100 km of heat networks. According to an emergency assessment, at least 15% of heating networks require urgent replacement. In addition to this, over the past 10 years, as a result of underfunding, the main fund of the industry has practically not been updated. As a result, heat energy losses during production, transportation and consumption reached 70%, which led to low quality heat supply at high costs.

Organizational structure interaction between consumers and heat supply companies does not stimulate the latter to save energy resources. The system of tariffs and subsidies does not reflect the real costs of heat supply.

In general, the critical situation in which the industry has found itself suggests that in the near future a large-scale crisis situation in the field of heat supply will arise, the resolution of which will require enormous financial investments.

An urgent issue is the reasonable decentralization of heat supply, apartment heating. Decentralization of heat supply (DT) is the most radical, efficient and cheap way to eliminate many shortcomings. Reasonable use of diesel fuel in combination with energy-saving measures in the construction and reconstruction of buildings will provide greater energy savings in Ukraine. In the current difficult conditions, the only way out is the creation and development of a diesel fuel system through the use of autonomous heat sources.

Apartment heat supply is an autonomous supply of heat and hot water to an individual house or a separate apartment in a multi-storey building. The main elements of such autonomous systems are: heat generators - heaters, pipelines for heating and hot water supply, fuel supply, air and smoke exhaust systems.

The objective prerequisites for the introduction of autonomous (decentralized) heat supply systems are:

the absence in some cases of free capacities at centralized sources;

densification of the development of urban areas with housing objects;

in addition, a significant part of the development falls on areas with undeveloped engineering infrastructure;

lower capital investment and the possibility of phased coverage of thermal loads;

the ability to maintain comfortable conditions in the apartment at one's own will, which in turn is more attractive compared to apartments with centralized heat supply, the temperature in which depends on the directive decision on the beginning and end of the heating period;

appearance on the market of a large number of various modifications of domestic and imported (foreign) heat generators of low power.

Today, modular boiler plants have been developed and are being mass-produced, designed to organize autonomous diesel fuel. The block-modular principle of construction provides the possibility of simple construction of a boiler house of the required power. The absence of the need to lay heating mains and build a boiler house reduces the cost of communications and can significantly increase the pace of new construction. In addition, this makes it possible to use such boiler houses for the prompt provision of heat supply in emergency and emergency situations during the heating season.

Block boiler rooms are a fully functionally finished product, equipped with all necessary appliances automation and security. The level of automation ensures the smooth operation of all equipment without the constant presence of an operator.

Automation monitors the object's need for heat depending on weather conditions and independently regulates the operation of all systems to ensure the specified modes. This achieves better compliance with the thermal schedule and additional fuel savings. In the event of emergency situations, gas leaks, the security system automatically stops the gas supply and prevents the possibility of accidents.

Many enterprises, oriented to today's conditions and having calculated economic benefit, are moving away from district heating, from remote and energy-intensive boiler houses.

The advantages of decentralized heat supply are:

no need for land allotments for heating networks and boiler houses;

reduction of heat losses due to the absence of external heating networks, reduction of network water losses, reduction of water treatment costs;

a significant reduction in the cost of repair and maintenance of equipment;

full automation of consumption modes.

If we take into account the lack of autonomous heating from small boiler houses and relatively low chimneys and, in connection with this, environmental damage, then a significant reduction in gas consumption associated with the dismantling of the old boiler house also reduces emissions by 7 times!

With all its advantages, decentralized heat supply also has negative sides. In small boiler houses, including "roof" ones, the height of the chimneys, as a rule, is much lower than in large ones, because of the dispersion conditions deteriorate sharply. In addition, small boiler houses are located, as a rule, near the residential area.

The introduction of programs for the decentralization of heat sources makes it possible to halve the need for natural gas and several times reduce the cost of heat supply to end consumers. The principles of energy saving laid down in the current heating system of Ukrainian cities stimulate the emergence of new technologies and approaches that can fully solve this problem, and the economic efficiency of diesel fuel makes this area very attractive for investment.

The use of an apartment heating system for multi-storey residential buildings makes it possible to completely eliminate heat losses in heating networks and during distribution between consumers, and significantly reduce losses at the source. It will allow organizing individual accounting and regulation of heat consumption depending on economic opportunities and physiological needs. Apartment heating will lead to a reduction in one-time capital investments and operating costs, and also saves energy and raw materials for the generation of thermal energy and, as a result, leads to a decrease in the burden on the environmental situation.

The apartment heating system is an economically, energetically, environmentally efficient solution to the issue of heat supply for multi-storey buildings. And yet, it is necessary to conduct a comprehensive analysis of the effectiveness of the use of a particular heat supply system, taking into account many factors.

Thus, the analysis of the components of losses in autonomous heat supply allows:

1) for the existing housing stock, increase the coefficient of energy efficiency of heat supply to 0.67 versus 0.3 for district heating;

2) for new construction, only by increasing the thermal resistance of enclosing structures, increase the coefficient of energy efficiency of heat supply to 0.77 versus 0.45 for centralized heat supply;

3) when using the entire range of energy-saving technologies, increase the coefficient to 0.85 against 0.66 with district heating.

3.2 Energy efficient solutions for diesel fuel

With autonomous heat supply, new technical and technological solutions can be used to completely eliminate or significantly reduce all unproductive losses in the chain of generation, transportation, distribution and consumption of heat, and not just by building a mini-boiler house, but by using new energy-saving and efficient technologies, such as how:

1) transition to a fundamentally new system of quantitative regulation of heat generation and supply at the source;

2) effective use of frequency-controlled electric drive on all pumping units;

3) reducing the length of circulating heating networks and reducing their diameter;

4) refusal to build central heating points;

5) transition to a fundamentally new scheme of individual heat points with quantitative and qualitative regulation depending on the current outdoor temperature using multi-speed mixing pumps and three-way regulator valves;

6) installation of a "floating" hydraulic mode of the heating network and a complete rejection of hydraulic balancing of consumers connected to the network;

7) installation of regulating thermostats on apartment heating appliances;

8) apartment-by-apartment wiring of heating systems with the installation of individual heat consumption meters;

9) automatic maintenance of constant pressure on hot water supply devices for consumers.

The implementation of these technologies makes it possible, first of all, to minimize all losses and creates conditions for the coincidence of the modes of the amount of generated and consumed heat in time.

3.3 Benefits of decentralized heating

If we trace the entire chain: source-transport-distribution-consumer, we can note the following:

1 Heat source - significantly reduced heat dissipation land plot, the cost of the construction part is reduced (no foundations are required for the equipment). The installed power of the source can be chosen almost equal to the consumed one, while it is possible to ignore the load of hot water supply, since during the maximum hours it is compensated by the storage capacity of the consumer's building. Today it is a reserve. Simplifies and reduces the cost of the control scheme. Heat losses are excluded due to the mismatch between the modes of production and consumption, the correspondence of which is established automatically. In practice, only the losses associated with the efficiency of the boiler remain. Thus, at the source it is possible to reduce losses by more than 3 times.

2 Heating networks - the length is reduced, the diameters are reduced, the network becomes more maintainable. A constant temperature regime increases the corrosion resistance of the pipe material. The amount of circulating water decreases, its losses with leaks. There is no need to build a complex water treatment scheme. There is no need to maintain a guaranteed differential pressure before entering the consumer, and in this regard, it is not necessary to take measures for the hydraulic balancing of the heating network, since these parameters are set automatically. Experts imagine what a difficult problem it is - to annually carry out hydraulic calculations and work on hydraulic balancing of an extensive heating network. Thus, losses in heat networks are reduced by almost an order of magnitude, and in the case of a roof-top boiler house for one consumer, these losses do not exist at all.

3 Distribution systems of TsTP and ITP. Required

> Documentation Modern heat supply systems (SHS) are quite complex technical systems with significant number elements of various functional purposes. characteristic. The paper selected the main indicators of heat supply and gas supply systems, which made it possible to substantiate the optimal heat supply schemes for the microdistrict. The analysis of the main factors influencing the operation of the heat supply system is given. Recommendations are given for choosing the optimal heat supply system. Russia inherited from the USSR high level centralization of heat supply. At the same time, combined generation of heat and electricity was ensured. The products of combustion were effectively cleaned and dispersed. But at the same time, the existing centralized heat supply systems have significant drawbacks. These are overheating of buildings during the transition period, large heat losses from pipes, disconnection of consumers for the period of preventive maintenance. The state of heat supply systems in Russia is critical. The number of accidents in heat supply networks has increased five times since 1991 (2 accidents per 1 km of heating networks). Of the 136,000 km of heating networks, 29,000 km are in disrepair. Heat losses during transportation of the coolant reach 65%. That is, every fifth ton of reference fuel is used to heat the atmosphere and soil. Reducing funding and poor translation quality worsen the situation. There is a contradiction, which lies in the fact that producers include excess heat losses in tariffs and demand payment for the heat produced, and not for the heat consumed. In addition, consumers must pay according to the area of ​​the heated premises, that is, regardless of the quantity and quality of the coolant. At present, interest in decentralized heat supply is extremely high. This is due to the appearance on the market of a wide variety of small automated boilers of foreign and domestic production, operating in automatic mode and because gas is used as fuel in such systems. Under such conditions, they become competitive with centralized sources, which are CHPs and large boiler houses. In Russia, several dozen multi-storey buildings with apartment heating up to five floors are in operation. The number of storeys is limited by current building codes. As an experiment, Gosstroy and the GUPO of the Ministry of Internal Affairs of the Russian Federation allowed the construction of 9-14-storey buildings with apartment heating in the Smolensk, Moscow, Tyumen, Saratov regions. When operating wall-mounted boilers with a closed firebox, air supply must be ensured not only for combustion, but also for 3-fold air exchange in the kitchen room, where they are usually installed. Smoke removal during apartment heating is associated with the construction of external and internal gas ducts made of corrosion-resistant metal with thermal insulation, which excludes condensation during periodic operation of heat generators during the transition period of the heating season. In high-rise buildings, there are problems with draft on the lower floors (highest draft) and upper (weak draft) floors. When using decentralized heating, basements and flights of stairs are not heated, which leads to freezing of the foundation and a decrease in the life of the building as a whole. Residents of apartments located in the central part can warm themselves at the expense of the owners of the surrounding apartments. A certain type of "energy parasites" is being created. The environmental parameters of wall-mounted boilers are normal and the NOx emission index is in the range of 30 to 40 mg/(kWh). At the same time, wall-mounted boilers have dispersed emissions of combustion products in a residential area at a relatively low height of chimneys, which has a significant impact on ecological situation , polluting the air in a residential area. In connection with the above disadvantages and advantages of centralized and autonomous heat supply systems, the question immediately arises: where and in what cases is it most appropriate to have autonomous heat supply, and in which centralized? After collecting all the necessary information, a comparison was made of four options for heat supply systems using the example of the Kurkino microdistrict in Moscow. At the same time, electric stoves are installed in all apartments. Option I - centralized heat supply from boiler houses. Option II - centralized heat supply from AIT (autonomous heat sources). Option III - decentralized heat supply from rooftop boilers. Option IV - apartment heat supply. In the first version, a district heating system was developed, where the source of heat is a boiler room, from which a two-pipe laying of heat networks to the central heating station is provided, and after the central heating station, a four-pipe installation for heating and hot water supply. In this case, the gas supply is carried out to the boiler room. In the fourth option, a local heat source is installed in the apartment, which provides the supply of coolant to the heating and hot water supply systems. In this scheme, a 2-stage gas supply system is proposed. The 1st stage is a medium-pressure gas pipeline, which is laid inside the quarter (a cabinet control point is installed in each house). 2nd stage - in-house low-pressure gas pipelines (gas is supplied only to a local heat source). The second and third options are intermediate between the first and fourth. In the second case, AIT (Autonomous Source of Heat) is used as a heat source, from which a two-pipe laying is provided from AIT to ITP (Individual Thermal Point), and from ITP - four-pipe for heating and hot water supply. In this case, it is planned to supply gas to AIT (autonomous heat sources) through medium pressure gas pipelines. In the third case, rooftop boiler houses of relatively low power (from 300 to 1000 kW) are used as a source of heat, which are located directly on the roof of the building and satisfy the need for heat for heating, ventilation and hot water supply. The gas pipeline to the boiler house is supplied along the outer wall of the building openly in places that are convenient for maintenance and exclude the possibility of damage. Variants of heat supply systems are shown in fig. 1. Technical solutions for heat supply based on several options should be made on the basis of technical and economic calculations, the best option of which is found by comparing possible solutions. The most expensive option for heat supply is the first - district heating from a boiler house. With such a system, most of the costs fall on heat networks, taking into account the CHP, which is 63.8% of the total cost of the system as a whole. Of these, only 84.5% fall on the laying of heating networks. The cost of the heat source itself is 34.7%, the share of gas networks, taking into account hydraulic fracturing and hydraulic fracturing, accounts for 1.6% of the total amount for the system. The fourth option (with apartment heat supply) is only 4.2% cheaper than the first (Fig. 2). So they can be taken as interchangeable. If in the first option most of the costs are heat networks, then with apartment heat supply - a source of heat, that is, wall-mounted boilers - 62.14% of the total cost of the system as a whole. In addition, apartment heating increases the cost of laying gas networks. It is worth paying attention to two other options. These are roof boiler rooms and AIT. From an economic point of view, the second option is the most profitable, that is, district heating from AIT (autonomous heat sources). In this option, most of the costs fall on heat networks, including ITP, which is 67.3% of the total cost of the system as a whole. Of these, the heating networks themselves account for 20.3%, the remaining 79.7% - for ITP. The cost of the heat source is 26%, the share of gas networks, taking into account hydraulic fracturing and hydraulic fracturing, accounts for 6.7% of the total amount for the system. The cost of laying pipes of the heat supply system depends on the length of the heat networks. Therefore, bringing the gas-fired heat source closer to the consumer by installing attached, built-in, roof and individual heat generators will significantly reduce system costs. In addition, statistics show that most of the failures of the district heating system occur in heat networks, which means that reducing the length of heat networks will entail an increase in the reliability of the heat supply system as a whole. Since the heat supply in Russia has a large social significance, improving its reliability, quality and economy is the most important task. Any failures in providing the population and other consumers with thermal energy have a negative impact on the country's economy and increase social tension. In the current tense situation, it is necessary to introduce resource-saving technologies. In addition, in order to increase the reliability of the heat pipelines being laid, it is necessary to use pre-insulated ductless pipes with polyurethane foam insulation in a polyethylene sheath (“pipe in pipe”). The essence of the reform of housing and communal services should not be an increase in tariffs, but the regulation of the rights and obligations of the consumer and producer of heat. It is necessary to agree on regulatory and legal issues and develop a base for technological regulation. All conditions for economic attractiveness for investment should be created. Rice. 1. Schematic diagrams of heat supply systems. 2. Schedule of reduced costs Literature 1. Economics of heat and gas supply and ventilation: Proc. for universities / L. D. Boguslavsky, A. A. Simonova, M. F. Mitin. - 3rd ed., revised. and additional - M.: Stroyizdat, 1988. - 351 p. 2. Ionin A. A. et al. Heat supply. - M .: Stroyizdat, 1982. - p. 336. Materials of the International Scientific and Technical Conference " Theoretical basis Heat and Gas Supply and Ventilation”, November 23 – 25, 2005, MGSU The article considers the issues of optimizing the parameters of the functioning of the heat supply system using exergy methods. These methods include the method of thermoeconomics, which combines both thermodynamic and economic components of systems analysis. The models obtained as a result of applying this method make it possible to obtain the optimal parameters for the functioning of the heat supply system, depending on external influences. Modern heat supply systems (SHS) are quite complex technical systems with a significant number of elements that are diverse in their functional purpose. Characteristic for them is the commonality of the technological process of obtaining steam or hot water at the boiler house due to the energy released during the combustion of fossil fuels. This allows in various economic and mathematical models to take into account only the final result of the operation of the STS - the supply of heat Qpot to the consumer in thermal or cost terms, and as the main factors determining the value of Qpot, to consider the costs of production and transportation of heat: the cost of fuel, electricity and other materials, wages, depreciation and repair of equipment, etc. Overview of methods thermodynamic analysis allows us to conclude that it is expedient to optimize the parameters of CTS functioning using exergy methods. These methods include the method of thermoeconomics, which successfully combines both thermodynamic and economic components of the CTS analysis. The main idea of ​​the thermoeconomics method is the use of a certain generalized thermodynamic characteristic to assess the changes occurring in the energy system, which ensures the final beneficial effect. Taking into account that in STS energy can be transferred both in the form of heat and in the form of mechanical work, exergy was chosen as a generalized thermodynamic characteristic. The exergy of heat should be understood as the work that can be obtained in a reversible direct cycle when a certain amount of heat Qh passes from a heating source with a temperature Th to an environment with a temperature Toc: where hT is the thermal efficiency of a direct reversible cycle. When using the thermoeconomic method, the changes that occur with the main exergy flow are analyzed, providing a useful final effect (in the case of CTS analysis, the exergy of the air in the room). At the same time, exergy losses that occur during the transmission and conversion of energy in individual elements of the CTS, as well as economic costs associated with the operation of the corresponding elements of the CTS, the presence of which is determined by the selected scheme, are considered and taken into account. An analysis of the changes undergone only by the main exergy flow, which provides a useful final effect, makes it possible to represent the thermoeconomic model of CTS in the form of a series of separate zones connected in series. Each zone is a group of elements that have relative independence within the system. Such a linearized representation technological scheme CTS greatly simplifies all further calculations by excluding individual technological links from consideration. Thus, the method of thermoeconomics, including the thermoeconomic model of the CTS, makes it possible to optimize the parameters of the CTS functioning. On the basis of the thermoeconomics method, a thermoeconomic model of the STS is developed, the schematic diagram of which is shown in fig. 1, where the water heating system with artificial water circulation is connected to the heating network according to an independent scheme. Rice. Fig. 1. Schematic diagram of the STS. 1 shows the elements of the STS that are taken into account when developing the model: 11 - a pump (compressor) with an electric motor for supplying fuel to the boiler unit; 12 - heat exchanger (boiler); 13 - network pump with an electric motor to ensure water circulation in the heating network; 14 - supply heat pipe; 15 - return heat pipe; 211 - water-to-water heat exchanger of a local heating point; 221 - circulation pump of the local heating system with an electric motor; 212 - raw water heater; 222 - source water pump with electric motor; 232 - make-up pump with an electric motor; 31 - heating appliances. When constructing a thermoeconomic model of CTS, the function of energy costs is used as an objective function. Energy costs, directly related to the thermodynamic characteristics of the system, determine, taking into account exergy, the cost of all flows of matter and energy entering the system under consideration. In addition, to simplify the resulting expressions, the following assumptions were made: · Changes in pressure losses in heat pipelines during transportation of the coolant are not taken into account. Pressure losses in pipes and heat exchangers are considered constant and independent of the operating mode; Exergy losses occurring in auxiliary heat pipelines (pipes in the boiler room) and heat pipelines of the heating system (internal pipes) as a result of heat exchange between the coolant and the environment are considered constant, independent of the STS operation mode; · exergy losses caused by water leaks from the network are considered constant, independent of the STS operation mode; · the heat exchange of the working fluid with the environment, which takes place in the boiler, tanks for various purposes (calciners, storage tanks) and heat exchangers through their outer surface washed by air, is not taken into account; heating of the coolant by transferring additional heat from the flue gases to it, as well as heating the air entering the furnace by the heat of the exhaust gases, are not optimized in this case. It is believed that the main part of the flue gas heat is used to heat the feed or network water in the economizer. The remaining part of the heat of the flue gases is released into the atmosphere, while the temperature of the flue gases Tg in the steady state operation of the boiler unit is assumed to be 140 °C; · heating of pumped water in pumps is not taken into account. Taking into account the stated initial provisions and the assumptions made, the thermoeconomic model of STS, the schematic diagram of which is shown in fig. 1 can be represented as three zones connected in series, shown in Fig. 2 and limited by the control surface. Zone 1 combines a pump (compressor) with an electric motor for supplying fuel to the boiler unit 11, a heat exchanger (boiler) 12, a network pump with an electric motor for supplying coolant to consumers 13, supply 14 and return 15 heat pipes. Zone 2(1) includes the water-to-water heat exchanger of the local heating point 211 and the circulation pump with an electric motor 221, and zone 2(2) includes the raw water heater 212, the raw water pump with an electric motor 222 and the make-up pump with an electric motor 232. Zones 2(1 ) and 2(2) are parallel connection individual elements of the thermoeconomic model of a multi-purpose STS, which provides heat supply to objects with different temperatures. Zone 3 includes heaters 31. From an external source through the control surface, exergy is supplied to various zones of the thermoeconomic model of the STS: e11 - to drive the electric motor of the fuel pump (compressor); e13 - to drive the electric motor of the network pump; e22 (1) - for driving the electric motor of the circulation pump; e22(2) - to drive the electric motor of the raw water pump; e23 (2) - to drive the electric motor of the make-up pump. The price of exergy supplied from an external source, i.e., electrical energy, is known and equal to Tsel. The equality of electrical energy and exergy is explained by the fact that electrical energy can be completely converted into any other form of energy. Fuel is supplied from an external source, the consumption of which is equal to vt, and the price is Pt. Since thermal processes occupy the main place in the process of CTS functioning, the variables to be optimized are those that make it possible to develop a thermoeconomic model of CTS and provide a relatively simple determination of the temperature conditions for the processes occurring in CTS. When solving the problem of static optimization of the CTS, taking into account the assumptions made and the accepted designations, the value of energy costs, including the costs of electrical energy and fuel, is determined by the dependence: where t is the operating time of the CTS. The consumption of electrical energy to drive the pump motors and the fuel consumption depend on the mode of operation of the STS, and hence on the temperature differences in the heat exchangers, the temperature of the flue gases and the interval of change in the temperature of the coolant. Therefore, the right side of expression (2) is a function of the chosen optimized variables. Consequently, the value of energy costs is a function of several variables, the extreme value of which is determined under the condition that the partial derivatives of the function of energy costs with respect to the variables being optimized are equal to zero. This approach is valid if all the variables being optimized are considered independent and the problem is reduced to determining the unconditional extremum. In fact, these variables are related. Obtaining analytical expressions that describe the relationship between all optimizing variables seems to be a rather difficult task. At the same time, the use of the thermoeconomic method in the course of research makes it possible to simplify this task. As shown in fig. 2, the CTS thermoeconomic model is presented as a series of series-connected zones, which makes it possible to express the exergy supplied to each of the zones in the form of functional dependencies on the exergy flow leaving the zone under consideration and the optimized variables affecting this zone. Taking into account the above, the amount of exergy supplied to various elements of the STS from an external source ej (see Fig. 2), and the volumetric fuel consumption vt, can be generally represented as follows: The equations included in the system (4) refer to different zones of the thermoeconomic model, the connection between which is carried out by the main flow of exergy. The exergy flow connecting individual zones is presented as a functional dependence on the exergy flow leaving the zone and the optimized variables affecting the zone under consideration: In expressions (4) and (5), ej means the amount of exergy, and Ej is a function that describes its change. The presence of links between the variables being optimized forces us to consider the optimization of the magnitude of energy costs as a problem of optimizing a function of several variables in the presence of constraints such as equalities (relationship equations), i.e., as a problem of finding a conditional extremum. Problems related to finding a conditional extremum can be solved using the Lagrange method of indefinite multipliers. The application of the method of indefinite Lagrange multipliers reduces the problem of finding the conditional extremum of the original function of energy costs (1) to the problem of finding the unconditional extremum of a new function - the Lagrangian. Taking into account the above systems of equations (4) and (5), the Lagrangian expression for the considered problem of optimizing the parameters of the functioning of the STS is written as follows: ) one can verify that they are completely identical. To find the extremum conditions, the partial derivatives of the Lagrange function (6) with respect to all variables (both optimized and additional, which are introduced by the constraint equations) must be taken and set equal to zero. Partial derivatives with respect to the exergy flows linking individual zones of the thermoeconomic model ej make it possible to calculate the values ​​of the Lagrange multipliers lj. Thus, the partial derivative with respect to e2(1) has the following form: The system of equations (8) establishes a relationship between energy dissipation and energy costs in each zone of the thermoeconomic model for certain values ​​of economic indicators Tel, Ts, l2(1), l2(2), l3. The quantities l2(1), l2(2), l3 in general case express the rate of change in energy costs when the amount of exergy changes, or in other words, the price of a unit of exergy leaving each zone of the thermoeconomic model. The solution of system (8), taking into account equations (7), allows us to determine the necessary conditions to find the minimum of the Lagrangian (6). To solve the systems of equations (7) and (8), expressions (4) and (5), written in general form, must be presented in the form of detailed analytical relations, which are components of the mathematical description of the processes occurring in individual elements of the CTS. Literature Brodyansky V. M., Fratsher V., Michalek K. Exergetic method and its applications. Under. ed. V. M. Brodyansky - M.: Energoatomizdat, 1988. - 288 p.

Right choice, competent design and high-quality installation of the heating system is a guarantee of warmth and comfort in the house during the entire heating season. Heating must be of high quality, reliable, safe, economical. To choose the right heating system, you need to familiarize yourself with their types, features of installation and operation of heating devices. It is also important to consider the availability and cost of fuel.

Types of modern heating systems

A heating system is a complex of elements used to heat a room: a heat source, pipelines, heating devices. Heat is transferred with the help of a coolant - a liquid or gaseous medium: water, air, steam, fuel combustion products, antifreeze.

Heating systems of buildings must be selected in such a way as to achieve the highest quality heating while maintaining comfortable air humidity for a person. Depending on the type of coolant, the following systems are distinguished:

• air;
• water;
• steam;
• electrical;
• combined (mixed).

Heating devices of the heating system are:

• convective;
• radiant;
• combined (convective-radiant).

Two-pipe scheme heating system with forced circulation

As a heat source can be used:

• coal;
• firewood;
• electricity;
• briquettes - peat or wood;
• energy from the sun or other alternative sources.

The air is heated directly from the heat source without the use of an intermediate liquid or gaseous heat carrier. The systems are used to heat private houses of a small area (up to 100 sq.m.). Installation of heating of this type is possible both during the construction of a building and during the reconstruction of an existing one. A boiler, heating element or gas burner serves as a heat source. The peculiarity of the system is that it is not only heating, but also ventilation, since the internal air in the room is heated and the fresh air coming from outside. Air streams enter through a special intake grille, are filtered, heated in a heat exchanger, after which they pass through the air ducts and are distributed in the room.

Adjustment of temperature and degree of ventilation is carried out by means of thermostats. Modern thermostats allow you to pre-set a program of temperature changes depending on the time of day. The systems also operate in air conditioning mode. In this case, the air flows are directed through the coolers. If there is no need for space heating or cooling, the system works as a ventilation system.

Diagram of an air heating device in a private house

Installation of air heating is relatively expensive, but its advantage is that there is no need to warm up the intermediate coolant and radiators, due to which fuel savings are at least 15%.

The system does not freeze, responds quickly to changes temperature regime and warms up the room. Thanks to the filters, the air enters the premises already purified, which reduces the number of pathogenic bacteria and contributes to the creation of optimal conditions for maintaining the health of people living in the house.

The lack of air heating is overdrying of the air, burning out oxygen. The problem is easily solved by installing a special humidifier. The system can be upgraded to save money and create a more comfortable microclimate. So, the recuperator heats the incoming air, due to the output to the outside. This reduces the energy consumption for its heating.

Additional purification and disinfection of air is possible. To do this, in addition to the mechanical filter included in the package, electrostatic fine filters and ultraviolet lamps are installed.

Air heating with additional appliances

Water heating

This is a closed heating system, it uses water or antifreeze as a coolant. Water is supplied through pipes from the heat source to the heating radiators. In centralized systems, the temperature is regulated at the heating point, and in individual systems - automatically (using thermostats) or manually (tap).

Types of water systems

Depending on the type of connection of heating devices, the systems are divided into:

• single-pipe,
• two-pipe,
• bifilar (two-furnace).

According to the method of wiring, they distinguish:

• top;
• bottom;
• vertical;
• horizontal heating system.

In single-pipe systems, the connection of heating devices is in series. To compensate for the loss of heat that occurs during the successive passage of water from one radiator to another, heaters with different heat transfer surfaces are used. For example, cast iron batteries with large quantity sections. In two-pipe, a parallel connection scheme is used, which allows you to install the same radiators.

The hydraulic mode can be constant and variable. In bifilar systems, heating devices are connected in series, as in single-pipe systems, but the heat transfer conditions for radiators are the same as in two-pipe systems. Convectors, steel or cast iron radiators are used as heating devices.

Scheme of two-pipe water heating of a country house

Advantages and disadvantages

Water heating is widespread due to the availability of the coolant. Another advantage is the ability to equip the heating system with your own hands, which is important for our compatriots who are accustomed to relying only on their own strength. However, if the budget allows not to save, it is better to entrust the design and installation of heating to specialists.

This will save you from many problems in the future - leaks, breakthroughs, etc. Disadvantages - freezing of the system when turned off, long time space heating. Special requirements apply to the coolant. Water in the systems must be free of impurities, with a minimum salt content.

To heat the coolant, a boiler of any type can be used: on solid, liquid fuel, gas or electricity. Most often used gas boilers, which involves connecting to the highway. If this is not possible, then usually set solid fuel boilers. They are more economical than electric or liquid fuel designs.

Note! Experts recommend choosing a boiler based on a power of 1 kW per 10 sq.m. These figures are indicative. If the ceiling height is more than 3 m, the house has large windows, there are additional consumers, or the premises are not well insulated, all these nuances must be taken into account in the calculations.

Closed house heating system

In accordance with SNiP 2.04.05-91 "Heating, ventilation and air conditioning", the use of steam systems is prohibited in residential and public buildings. The reason is the insecurity of this type of space heating. Heaters heat up to almost 100°C, which can cause burns.

Installation is complex, requires skills and special knowledge, during operation there are difficulties with the regulation of heat transfer, noise is possible when filling the system with steam. Today, steam heating is used to a limited extent: in industrial and non-residential premises, in pedestrian crossings, and heating points. Its advantages are relative cheapness, low inertia, compactness of heating elements, high heat transfer, no heat loss. All this led to the popularity of steam heating until the middle of the twentieth century, later it was replaced by water heating. However, in enterprises where steam is used for industrial needs, it is still widely used for space heating.

Boiler for steam heating

Electric heating

This is the most reliable and easiest type of heating in operation. If the area of ​​the house is not more than 100 m, electricity - good option However, heating a larger area is not economically viable.

Electric heating can be used as an additional in case of a shutdown or repair of the main system. Also this good decision for country houses in which the owners live only occasionally. Electric fan heaters, infrared and oil heaters are used as additional heat sources.

Convectors, electric fireplaces, electric boilers, floor heating power cables are used as heating devices. Each type has its own limitations. So, convectors heat the rooms unevenly. Electric fireplaces are more suitable as a decorative element, and the operation of electric boilers requires significant energy costs. The underfloor heating is mounted with advance consideration of the furniture arrangement plan, because when it is moved, the power cable may be damaged.

Scheme of traditional and electric heating of buildings

Innovative heating systems

Separately, mention should be made of innovative heating systems, which are becoming increasingly popular. The most common:

• infrared floors;
• heat pumps;
• solar collectors.

infrared floors

These heating systems have only recently appeared on the market, but have already become quite popular due to their efficiency and greater economy than conventional electric heating. Warm floors are powered by the mains, they are installed in a screed or tile adhesive. Heating elements (carbon, graphite) emit infrared waves that pass through the floor covering, heat up the bodies of people and objects, which in turn heats up the air.

Self-adjusting carbon mats and foils can be mounted under furniture legs without fear of damage. "Smart" floors regulate the temperature due to the special property of the heating elements: when overheated, the distance between the particles increases, the resistance increases - and the temperature decreases. Energy costs are relatively low. When the infrared floors are turned on, the power consumption is about 116 watts per linear meter, after warming up it decreases to 87 watts. Temperature control is provided by thermostats, which reduces energy costs by 15-30%.

Infrared carbon mats are convenient, reliable, economical, easy to install

Heat pumps

These are devices for transferring thermal energy from a source to a coolant. In itself, the idea of ​​a heat pump system is not new; it was proposed by Lord Kelvin back in 1852.

How it works: A geothermal heat pump takes heat from the environment and transfers it to the heating system. The systems can also work to cool buildings.

How a heat pump works

There are pumps with open and closed cycle. In the first case, the installations take water from the underground stream, transfer it to the heating system, take heat energy and return it to the place of intake. In the second, a coolant is pumped through special pipes in the reservoir, which transfers / takes heat from the water. The pump can use the thermal energy of water, earth, air.

The advantage of the systems is that they can be installed in houses that are not connected to the gas supply. Heat pumps are complex and expensive to install, but they save on energy costs during operation.

The heat pump is designed to use the heat of the environment in heating systems

Solar collectors

Solar installations are systems for collecting solar thermal energy and transferring it to a coolant

Water, oil or antifreeze can be used as a heat carrier. The design provides for additional electric heaters that turn on if the efficiency of the solar installation decreases. There are two main types of collectors - flat and vacuum. An absorber with a transparent coating and thermal insulation is installed in the flat ones. In vacuum, this coating is multilayer, in hermetically sealed collectors a vacuum is created. This allows you to heat the coolant up to 250-300 degrees, while flat installations can only heat it up to 200 degrees. The advantages of the installations include ease of installation, low weight, and potentially high efficiency.

However, there is one “but”: the efficiency of the solar collector depends too much on the temperature difference.

Solar collector in the domestic hot water and heating system Comparison of heating systems shows that there is no ideal heating method

Our compatriots still most often prefer water heating. Usually, doubts arise only about which specific heat source to choose, how best to connect the boiler to the heating system, etc. And yet there are no ready-made recipes suitable for absolutely everyone. It is necessary to carefully weigh the pros and cons, take into account the features of the building for which the system is selected. If in doubt, a specialist should be consulted.

Video: types of heating systems

Modern heating systems are based on various heating methods, which allows you to choose the most suitable option for your country house. Technologies developed over the years will provide not only efficient space heating, but also independent temperature control in each room, fuel economy, automatic and remote control.

Used today in country houses heating and heat supply can be conditionally divided into two groups - classical and innovative. Each group is wide enough, so modern home heating allows you to choose the most effective option for you.

Classic heating systems

Boiler heating with a liquid heat carrier belongs to the classical one. Taking heat from the boiler, the coolant heats the radiators, which in turn release heat into the room by air convection. The boiler can use gas, electricity, diesel fuel or wood as fuel.

Some types of classical heating are getting more advanced options, turning into modern systems heating. For example, electric heating can be direct - the energy is immediately converted into heat without the use of a boiler, coolant, a complex system of pipes and radiators. Direct electric infrared heating is devoid of the disadvantage inherent in standard convection. Infra-red rays heat physical bodies, not air. The heated air does not accumulate under the ceiling, the room is heated more quickly and evenly. A direct electric heating system requires the least installation and maintenance costs.

Air heating also does not use an intermediate heat carrier. The air heated by the boiler through the air ducts immediately enters the heated room. Simultaneously with heating, this method allows for air conditioning and ventilation of rooms.

Modern heating systems sometimes turn to the past, not without success. For example, engineers were able to improve obsolete solid fuel heating. In a pyrolysis solid fuel boiler, the combustion of firewood occurs according to a complex scheme with the formation of combustible pyrolysis gas. Gas is afterburned in a separate furnace, as a result, the overall efficiency of the boiler increases.

The most important indicator of the effectiveness of modern autonomous heating is the possibility of flexible automatic, program and remote control. The most simple and effective automation lends itself to gas, electric and air heating. Thanks to flexible control, modern heating systems can be easily integrated into a "smart home", increasing the overall comfort of living.

Innovative heating systems

Modern heating systems are inseparable from the search for new solutions. The category of innovative includes all non-volatile heating technologies using renewable energy sources - solar radiation, wind and wave power, heat pump, etc. It is still too expensive, technologically difficult and not always effective to make modern heating systems for a summer house or a cottage non-volatile today. But every year technologies are improved, bringing closer the possibility of organizing completely independent heating. Currently, non-volatile technologies are used to organize additional, backup and emergency heating.

Whichever heating system of a country house you choose, you first need to minimize the heat loss of the building. To do this, when designing and building a house, special architectural solutions, energy-saving materials and technologies are used. Heat accumulators are actively used, which allow storing heat at night at reduced electricity tariffs.

Modern heating of a country house is characterized not only by efficiency, economy, but also by high performance. A professionally designed and installed heating system has a long service life, allows you to quickly maintain, repair and upgrade equipment.

Ministry of Education of the Russian Federation

Federal State Budgetary Educational Institution of Higher Professional Education "Magnitogorsk State Technical University

them. G.I. Nosov"

(FGBOU VPO "MGTU")

Department of Thermal Power and Energy Systems

abstract

in the discipline "Introduction to the direction"

on the topic: "Centralized and decentralized heat supply"

Completed by: student Sultanov Ruslan Salikhovich

Group: ZEATB-13 "Heat power engineering and heat engineering"

Code: 140100

Checked by: Agapitov Evgeny Borisovich, Doctor of Technical Sciences.

Magnitogorsk 2015

1.Introduction 3

2. District heating 4

3.Decentralized heat supply 4

4. Types of heating systems and principles of their operation 4

5.Modern systems of heating and hot water supply in Russia 10

6. Prospects for the development of heat supply in Russia 15

7. Conclusion 21

1. Introduction

Living in temperate latitudes, where the main part of the year is cold, it is necessary to provide heat supply to buildings: residential buildings, offices and other premises. Heat supply provides comfortable living if it is an apartment or a house, productive work if it is an office or a warehouse.

First, let's figure out what is meant by the term "Heat supply". Heat supply is the supply of heating systems of a building with hot water or steam. The usual source of heat supply is CHP and boiler houses. There are two types of heat supply for buildings: centralized and local. With a centralized supply, certain areas (industrial or residential) are supplied. For the efficient operation of a centralized heating network, it is built by dividing it into levels, the work of each element is to perform one task. With each level, the task of the element decreases. Local heat supply - the supply of heat to one or more houses. District heating networks have a number of advantages: reduced fuel consumption and cost reduction, use of low-grade fuel, improved sanitation of residential areas. The district heating system includes a source of thermal energy (CHP), a heat network and heat-consuming installations. CHP plants produce heat and energy in combination. Sources of local heat supply are stoves, boilers, water heaters.

Heating systems are characterized by different water temperatures and pressures. It depends on customer requirements and economic considerations. With an increase in the distance over which it is necessary to “transfer” heat, economic costs increase. At present, the heat transfer distance is measured in tens of kilometers. Heat supply systems are divided according to the volume of heat loads. Heating systems are seasonal, and hot water systems are permanent.

1. District heating

District heating is characterized by the presence of an extensive branched subscriber heating network with power supply to numerous heat receivers (factories, enterprises, buildings, apartments, residential premises, etc.).

The main sources for district heating are: - combined heat and power plants (CHP), which also generate electricity along the way; - boiler rooms (in heating and steam).

1. Decentralized heat supply

Decentralized heat supply is characterized by a heat supply system in which the heat source is combined with a heat sink, that is, there is little or no heating network at all. If separate individual electric or local heating heat sinks are used in the premises, then such heat supply will be individual (an example would be the heating of the entire building's own small boiler room). The power of such heat sources, as a rule, is quite small and depends on the needs of their owners. The heat output of such individual heat sources is not more than 1 Gcal/h or 1.163 MW.

The main types of such decentralized heating are:

Electric, namely: - direct; - accumulation; - heat pump; - oven. Small boiler houses.