Modern heat supply systems development prospects. A brief overview of modern heating systems for residential buildings and public buildings Electric heating boilers

MODERN HEATING SYSTEMS

(, Khabarovsk Center for Energy and Resource Saving)

In Khabarovsk and the Khabarovsk Territory, as in many other regions of Russia, “open” heat supply systems are predominantly used.

In thermodynamics, an “open” system is understood as a system that exchanges mass with its environment, i.e., a “loose” system.

In this publication, an “open” system is understood as a heat supply system in which the hot water supply (DHW) system is connected via an “open” system, i.e., with direct water withdrawal from the pipelines of the heating supply system, and the heating and ventilation system is connected according to a dependent connection scheme to heating networks.

Open heat supply systems have the following disadvantages:

1. High consumption of make-up water and, therefore, high costs for water treatment. With this scheme, the coolant can be used both productively (for the needs of hot water supply) and unproductively: unauthorized leaks.

Unauthorized leaks include:

Leaks through shut-off and control valves;

Leaks due to damaged pipelines;

Leaks through the risers of the heating system (discharges) with misregulated heating systems and with insufficient pressure drops at the elevator inputs;

Leaks (discharges) during repairs of the heating system, when you have to completely drain the water and then refill the system, and if the outlet valves do not “hold”, then you have to “de-energize” an entire block or tie-in.

An example is an accident in November 2001 in Khabarovsk in the Bolshaya - Vyazemskaya microdistrict. In order to repair the heating system in one of the schools, an entire block had to be turned off.

2. With an open DHW scheme, the consumer receives water directly from the heating network. In this case, hot water can have a temperature of 90°C or more and a pressure of 6-8 kgf/cm2, which leads not only to excessive heat consumption, but also potentially creates a dangerous situation for both sanitary equipment and people.

3. Unstable hydraulic heat consumption mode (one consumer instead of another).

4. Poor quality coolant, which contains a large amount of mechanical impurities, organic compounds and dissolved gases. This leads to a decrease in the service life of pipelines of heat supply systems due to increased corrosion and to a decrease in their throughput due to “fouling”, which disrupts the hydraulic regime.

5. It is, in principle, impossible to create comfortable conditions for the consumer when using elevator heating systems.

It is necessary to answer that almost all heating points of subscribers in Khabarovsk are equipped with elevator thermal input.

The main advantage of the elevator is that it does not consume energy for its drive. There is an opinion that the elevator has low efficiency, and this would be true if it would be necessary to consume energy to operate it. In fact, the pressure difference in the pipelines of the heating system is used to operate the mixing. If it weren’t for the elevator, we would have to throttle the coolant flow, and throttling is a loss of energy. Therefore, in relation to thermal inputs, an elevator is not a pump with low efficiency, but a device for recycling the energy spent on driving the circulation pumps of a thermal power plant. Another advantage of the elevator is that its maintenance does not require highly qualified specialists, since the elevator is a simple, reliable and unpretentious device to operate.

The main disadvantage of the elevator is the impossibility of proportional regulation of thermal power, since with the diameter of the nozzle apparatus opening not changing, it has a constant mixing coefficient, and the control process assumes the possibility of changing this value. For this reason, in the West, the elevator is rejected as a device for heating points. Note that this drawback can be eliminated if you use an elevator with an adjustable nozzle.

However, the practice of using elevators with an adjustable nozzle has shown their low reliability when the quality of the network water is poor (presence of mechanical impurities). In addition, such devices have a small control range. Therefore, these devices have not found widespread use in Khabarovsk.

Another disadvantage of the elevator is the unreliability of its operation with a small available pressure drop. For stable operation of the elevator, it is necessary to have a pressure drop of 120 kPa or more. However, to date, elevator units have been designed in Khabarovsk with a pressure drop of 30-50 kPa. With such a difference, normal operation of elevator units is, in principle, impossible and therefore very often consumers with such units work to “discharge”, which leads to excess losses of network water.

The use of elevator units hinders the implementation of energy-saving measures in heat supply systems, such as complex automatic control of coolant parameters in the building and a heating system design adequate to these tasks, ensuring accuracy and stability of comfortable conditions and economical heat consumption.

Complex automatic regulation includes the following basic principles:

regulation in individual heating points (IHP) or automated control units (ACU), ensuring, in accordance with the heating schedule, a change in the temperature of the coolant supplied to the heating system depending on the outside air temperature;

individual automatic control on each heating device using a thermostat, ensuring maintenance of the set temperature in the room.

All of the above led to the fact that, starting in 2000, a large-scale transition from “open” dependent heat supply systems to “closed” independent systems with automated heating points began in Khabarovsk.

Reconstruction of the heat supply system using energy-saving measures and the transition from “open” dependent systems to “closed” independent systems will allow:

Increase the comfort and reliability of heat supply by maintaining the required temperature in the premises, regardless of weather conditions and coolant parameters;

It will increase the hydraulic stability of the heat supply system: the hydraulic mode of the main heating networks is normalized due to the fact that the automation does not allow heat consumption to exceed the norm;

Receive heat savings of 10-15% by regulating the coolant temperature in accordance with the outside air temperature and reducing the temperature in heated buildings at night by up to 30% during the transition period of the heating season;

Increase the service life of the building heating system pipelines by 4-5 times, due to the fact that with an independent heat supply scheme, a clean coolant that does not contain dissolved oxygen circulates in the internal circuit of the heating system and therefore the heating devices and supply pipelines do not become clogged with dirt and corrosion products;

Dramatically reduce the recharge of heating networks and, consequently, the costs of water treatment, as well as improve the quality hot water.

The use of independent heat supply systems opens up new prospects in the development of intra-block networks and internal systems heating: use of flexible pre-insulated plastic distribution pipelines with a service life of about 50 years, polypropylene pipes for internal systems, stamped panel and aluminum radiators, etc.

However, the transition in Khabarovsk to modern heat supply systems with automated heating points has confronted design and installation organizations, energy supply organizations, and heat consumers with a number of problems, such as:

Lack of year-round coolant circulation in main heating networks.

An outdated approach to the design and installation of internal heat supply systems.

Need for maintenance modern systems heat supply.

Let's look at these problems in more detail.

Problem No. 1 Lack of year-round circulation in the main pipelines of heating networks.

In Khabarovsk, the main pipelines of the heat supply system are circulated only during the heating season: from approximately mid-September to mid-May. The rest of the time, the coolant flows through one of the pipelines: supply or return, and part of the time it is supplied through one pipeline, and partly through the other.

This leads to great inconvenience and additional costs when introducing energy-saving technologies in heat supply systems, in particular in hot water supply (DHW) systems. Due to the lack of circulation in the inter-heating season, it is necessary to use a mixed “open-closed” hot water system: “closed” in the heating season and “open” in the inter-heating season, which increases the capital costs for installation and equipment of the heating point by 0.5-3% .

Problem #2. An outdated approach to the design and installation of internal heat supply systems for buildings.

In the pre-perestroika period of development of our state, the government set the task of saving metal. In this regard, the mass introduction of single-pipe unregulated heating systems began, which was due to lower (compared to two-pipe) metal consumption, installation costs and higher thermal-hydraulic stability in multi-storey buildings.

Currently, when commissioning new facilities in Russian cities, such as Moscow and St. Petersburg, as well as in Ukraine, for the purpose of energy saving, it is mandatory to use thermostats in front of heating devices, which in fact, with minor exceptions, predetermines the design of two-pipe heating systems.

Therefore, the widespread use of single-pipe systems when equipping each heating device with a thermostat has lost its meaning. In adjustable heating systems, when installing a thermostat in front of the heating device, a two-pipe heating system turns out to be highly efficient and has increased hydraulic stability. At the same time, the differences in metal costs compared to single-pipe ones are within ±10%.

It should also be noted that single-pipe heating systems are practically not used abroad

Schemes of two-pipe systems can be different, but it is most advisable to use an independent scheme, since when using thermostats (thermostats), the dependent scheme is unreliable in operation due to the low quality of the coolant. With small holes in thermostats, measured in millimeters, they quickly fail.

It is proposed to use single-pipe heating systems with thermostats only for buildings of no more than 3-4 floors. It also notes that it is inappropriate to use cast iron heating devices in heating systems with thermostats, since during operation molding soil, sand, and scale are washed out of them, which clog the holes of the thermostats.

The use of independent heat supply schemes opens up new prospects: the use of polymer or metal-polymer pipelines for internal systems, modern heating devices (aluminum and steel heating devices with built-in thermostats).

It should be noted that a two-pipe heating system, unlike a single-pipe one, requires mandatory adjustment using special equipment and highly qualified specialists.

It should be noted that even when designing and installing automated heating points with weather control in Khabarovsk, only single-pipe heating systems without thermostats in front of the heating devices have been designed and implemented to date. Moreover, these systems are hydraulically unbalanced, and sometimes so much (for example, the orphanage on Lenin Street) that in order to maintain normal temperature in the building, the end risers work “to reset” and this is with an independent heating circuit!

I would like to believe that underestimation of the importance of balancing the hydraulics of heating systems is simply due to the lack of necessary knowledge and experience.

If Khabarovsk designers and installation organizations are asked the question: “Is it necessary to balance the wheels of a car?”, then the obvious answer will follow: “Undoubtedly!” But why then is balancing the heating, ventilation and hot water supply systems not considered necessary? After all, incorrect flow rates of the coolant lead to incorrect air temperatures in the room, poor operation of automation, noise, rapid failure of pumps, and uneconomical operation of the entire system.

Designers believe that it is enough to carry out a hydraulic calculation with the selection of pipes and, if necessary, washers, and the problem will be solved. But that's not true. Firstly, the calculation is approximate, and, secondly, during installation a lot of additional uncontrollable factors arise (most often, installers simply do not install throttle washers).

There is an opinion that the hydraulics of heating systems can be linked by calculating the settings of thermostatic valves. This is also incorrect. For example, if for some reason a sufficient amount of coolant does not pass through the riser, then the thermostatic valves will simply open, and the air temperature in the room will be low. On the other hand, if there is an excessive consumption of coolant, a situation may arise when the vents and thermostatic valves are open. All of the above does not at all detract from the need and importance of installing thermostatic valves in front of heating devices, but only emphasizes that for their good operation it is necessary to balance the system.

By balancing the system we mean adjusting the hydraulics so that each element of the system: radiator, heater, branch, arm, riser, main has the design costs. In this case, determining and setting the settings of thermostatic valves is part of the commissioning process.

As stated above, in Khabarovsk only hydraulically unbalanced single-pipe heating systems without thermostats are designed and installed.

Let us show, using examples of new facilities being commissioned, what this leads to.

Example 1. Orphanage No. 1 on the street. Lenin.

Put into operation at the end of 2001. The hot water supply system is closed, and the heating system is single-pipe, without thermostats, connected according to an independent circuit. Designed by Khabarovskgrazhdanproekt, installation of the heating and hot water system by Khabarovsk Installation Department No. 1. Design and installation of the heating point - specialists from KhTSES. The heating unit is undergoing maintenance at KhTSES.

After the launch of the heat supply system, the following shortcomings were revealed:

The heating system is not balanced. In some rooms there was overheating: 25-27°C, and in others underheating: 12-14°C. This is due to several reasons:

to balance the heating system, the designers provided washers, but the installers did not cut them in, citing the fact that “they will still clog in 2-3 weeks”;

individual heating devices are made without closing sections, their surface is overestimated, which leads to overheating of individual rooms.

In addition, in order to ensure circulation and normal temperature, in sub-heated rooms, the end risers worked as a “discharge”, which led to water leaks of 20-30 tons per day, and this is with an independent circuit!!!

System supply ventilation does not work, and this is unacceptable, since the building has thermostatic windows with low air permeability.

At the request of the Customer, KhTSES specialists installed balancing fittings on the risers and carried out balancing of the heating system. As a result, the temperature in the rooms leveled out and amounted to 20-22 ° C, the system recharge was reduced to zero, and thermal energy savings amounted to about 30%. The ventilation system was not adjusted.

Example 2. Institute for Advanced Training of Doctors.

Commissioned in October 2002. The hot water system is closed, the heating system is single-pipe without thermostats and connected according to an independent circuit.

After launching the heating system, the following shortcomings were identified: the heating system is not balanced, there are no fittings for adjusting the system (the design does not even provide throttle washers). The air temperature in the rooms varies from 18 to 25°C, and in order to bring the temperature in the corner rooms to 18°C, it was necessary to increase the heat consumption by 3 times compared to the required one. That is, if the heat consumption of the building is reduced by three times, then in most rooms the temperature will be 18-20°C, but in the corner rooms the temperature will not exceed 12°C.

These examples apply to all newly introduced buildings with independent heating schemes in Khabarovsk: the circus and the circus hotel (the windows in the hotel are open (overflow), and in the backstage area it is cold (underflow), residential buildings on Fabrichnaya street, Dzerzhinsky street, therapeutic building of the Railway Hospital, etc.

Problem No. 2 is closely intertwined with problem No. 3.

Problem #3. The need for maintenance of modern heating systems.

As our three-year experience shows, modern heating systems for buildings, made using energy-saving technologies, require constant maintenance during operation. To do this, it is necessary to attract highly qualified, specially trained specialists, using special technologies and tools.

Let's show this using examples of automated heating points implemented in Khabarovsk.

Example 1. Heating points not serviced by specialized organizations.

In 1998, the Hacobank building on Leningradskaya Street in Khabarovsk was put into operation in Khabarovsk. The building's heat supply system was designed and installed by specialists from Finland. The equipment used is also Finnish. The heating system is made according to an independent two-pipe circuit with thermostats and is equipped with balancing fittings. The DHW system is closed. The system was maintained by bank specialists. During the first three years of operation, a comfortable temperature was maintained in all rooms. After 3 years, there were complaints from residents of individual apartments that the apartment was “cold.” Residents turned to HCES with a request to inspect the system and help establish a “comfortable” mode.

An inspection of the HCES showed that the automatic control system does not work (the ECL weather regulator has failed), the heat exchange surfaces of the heating system heat exchanger are clogged, which led to a decrease in its heating capacity by approximately 30% and an imbalance in the heating system.

A similar picture was observed in a residential building on the street. Dzerzhinsky 4, where the modern heating system was maintained by the residents.

Example 2. Heating points serviced by specialized organizations.

Today, the Khabarovsk Center for Energy and Resources Conservation has about 60 automated heating points under maintenance. As our operating experience has shown, during the maintenance of such units the following problems arise:

cleaning filters installed in front of hot water supply and heating heat exchangers and in front of circulation pumps;

control over the operation of pumps and heat exchange equipment;

control over the operation of automation and regulation.

The quality of the coolant and even cold water in Khabarovsk is very low and therefore the problem of cleaning the filters that are installed in the primary circuit of the hot water supply and heating heat exchangers, before the circulation pumps in the secondary circuit of the heat exchangers, constantly arises. For example, when commissioning in the heating season 2002/03. block of residential buildings on Fabrichny Lane, in each of which an IHP was installed, the filter installed in the primary circuit of the heating heat exchanger had to be washed 1-2 times a day during the first 10 days after launch and then, in the next two weeks, at least once once every 2-3 days. On the building of the circus and the circus hotel in the heating season 2001/02. I had to wash the cold water filter 1-2 times a week.

It would seem that cleaning a filter installed in the primary circuit is a routine operation that can be performed by an unqualified specialist. However, to clean (flush) the filter, it is necessary to stop the entire heating system for a while, turn off the cold water, turn off the circulation pump in the hot water system and then start it all again. Also, when turning off the heat supply system to clean the filters, it is advisable to turn off and then restart the automation system so that water hammer does not occur when the heat supply system is started. Moreover, if, when turning off the primary circuit of the DHW system, you do not turn off the secondary circuit for cold water, then due to temperature expansions a “leak” may appear in the DHW heat exchanger.

The second problem that arises during the operation of automated heating points is the problem of monitoring the operation of equipment: pumps, heat exchangers, metering and control devices.

For example, often before starting up after the inter-heating period, circulation pumps are in a “dry” state, that is, they are not filled with network water, and their gland seals dry out, and sometimes even stick to the pump shaft. Therefore, before starting, in order to avoid leakage of network water through the gland seals, it is necessary to smoothly turn the pump several times by hand.

Also, during operation, it is necessary to periodically monitor the operation of control valves so that they do not constantly operate in the “closed” or “open” mode, pressure regulators, differential pressure, etc., in addition, it is necessary to monitor changes in the hydraulic resistance and heat transfer surface of the heat exchangers .

Changes in hydraulic resistance and the area of ​​the heat transfer surface of heat exchangers can be monitored by recording or periodically measuring the temperature of the coolant in the primary and secondary circuits of the heat exchanger and the pressure drop and coolant flow in these circuits.

For example, in the heating season 2001/02. in the circus hotel, a month after the start of operation, the temperature of the hot water dropped sharply. Research has shown that at the beginning of operation, the coolant flow rate in the primary circuit of the hot water supply system was 2-3 t/hour, and a month after the start of operation it was no more than 1 t/hour. This happened due to the fact that the primary circuit of the DHW heat exchanger was clogged with welding products (scale), which led to an increase in hydraulic resistance and a decrease in the area of ​​the heat transfer surface. After the heat exchanger was disassembled and washed, the hot water temperature reached normal.

As experience in servicing modern heat supply systems with automated heating points has shown, during their operation it is necessary to constantly monitor and make adjustments to the operation of automation and control systems. In Khabarovsk, over the past 3-5 years, the temperature schedule of 130/70 has not been observed: even at temperatures below minus 30°C, the coolant temperature at the inlet of subscribers does not exceed 105°C. Therefore, HCES specialists servicing automated heating points, based on statistical observations of the heat consumption regime of objects before the start of the heating season for each object, enter their own temperature schedule into the controller, which is then adjusted during the heating season.

The problem of servicing automated heating points is closely related to the lack of a sufficient number of highly qualified specialists, who are not purposefully trained within the Far Eastern region. At the Khabarovsk Center for Energy and Resource Saving, the maintenance of automated heating units is carried out by specialists - graduates of the Department of Heat Engineering, Heat and Gas Supply and Ventilation of the Khabarovsk State Technical University, who were trained at equipment manufacturers (Danfos, Alfa-Laval, etc.).

Note that HCES is a regional service center for companies that supply equipment for automated heating points, such as: Danfos (Denmark) - supplier of controllers, temperature sensors, control valves, etc.; Wilo (Germany) - supplier of circulation pumps and pump automation; Alfa Laval (Sweden-Russia) – supplier of heat exchange equipment; TBN "Energoservice" (Moscow) - supplier of heat meters, etc.

In accordance with the service partnership agreement concluded between HCES and Alfa Laval, HCES carries out maintenance work on Alfa Laval heat exchange equipment, using personnel trained at the Alfa Laval service center, and using for these purposes only authorized Alfa Laval original spare parts and materials for operation.

In turn, Alfa-Laval supplied HCES with equipment, tools, consumables and spare parts necessary for servicing Alfa-Laval plate heat exchangers, and trained HCES specialists in its service center.

This allows KhTSES to carry out dismountable and in-place washing of heat exchangers directly at consumers in Khabarovsk.

Therefore, all issues related to the operation and repair of equipment of automated heating points are resolved locally - in Khabarovsk.

We also note that, unlike other companies involved in the implementation of automated heating points, KhTSES installs more expensive, but more reliable and higher quality equipment (for example, collapsible rather than soldered heat exchangers, pumps with a dry rather than wet rotor). This guarantees reliable operation of the equipment for 8-10 years.

The use of cheap but lower quality equipment does not guarantee uninterrupted operation of automated heating units. As our experience shows, as well as the experience of other companies, this equipment usually fails after 2-3 years and the consumer begins to feel thermal discomfort (see, for example, example 1 from problem No. 3).

Thermal tests of heat exchangers carried out in St. Petersburg showed:

The decrease in the thermal efficiency of the heat exchanger is 5% after the first year, 15% after the second, more than 25% after the third, 35% after the fourth, and 40-45% after the fifth;

A decrease in the thermal performance of the apparatus and the heat transfer coefficient is associated with contamination of the heat exchange surface both from the primary circuit and from the secondary circuit; these contaminants appear in the form of deposits, and on the side of the primary contour the deposits are brown in color, and on the side of the secondary contour they are black;

The brown color of deposits is determined mainly by iron oxides, which are formed in network water due to corrosion of the inner surface of heating pipelines; These contaminations from the primary circuit can be easily removed using a soft cloth under running warm water;

The black color of secondary circuit deposits is determined mainly by organic compounds, which are found in large quantities in the secondary circuit water, which circulates through the closed circuit of the building's heating system and is not subject to any treatment; it is not possible to remove deposits from the side of the secondary circuit in the same way as from the primary circuit, since they are not loose, but dense; to clean the heat exchange plates on the side of the secondary circuit, the plates had to be soaked in kerosene for 15-20 minutes, and then they were wiped with considerable effort with damp rags soaked in kerosene;

Due to the fact that biological deposits formed on the plates from the side of the secondary circuit have very strong adhesion to the metal surface, in-place chemical flushing of the secondary circuit does not give satisfactory results.

Cheap equipment, as a rule, is used by those implementation companies that do not provide service maintenance for the equipment they have implemented, since this requires having the appropriate equipment and materials, as well as qualified personnel, i.e., investing significant funds in the development of their production base.

Therefore, the consumer is faced with a choice:

Spend a minimum of capital investments and introduce cheap equipment (motor-rotor pumps, soldered heat exchangers, etc.), which in 2-3 years will significantly lose its properties or become completely unusable; at the same time, operating costs for repairs and maintenance of equipment after 2-3 years will increase sharply and may be of the same order as the initial investment;

Expend maximum capital investments, introduce reliable, expensive equipment (gasketed heat exchangers from trusted companies, for example Alfa-Laval, dry-motor pumps with frequency drives, reliable automation, etc.) and thereby significantly reduce your operating costs.

The choice remains with the consumer, but we must not forget that “the miser pays twice.”

Summarizing the above, we can draw the following conclusions:

1. In Khabarovsk, in the last 2-3 years, the process of transition from outdated “open” systems to modern “closed” heat supply systems with the introduction of energy-saving technologies has begun. However, to speed up this process and make it irreversible, it is necessary:

1.1. To change the psychology of Customers, designers, installers and operators, which is as follows: it is easier and cheaper to implement outdated traditional heat supply schemes with single-pipe heating systems and elevator units that do not require maintenance and adjustment, than to create additional pain and financial difficulties for yourself by moving to modern heat supply systems with automation and control systems. That is, build an object with a minimum of capital costs, then transfer it, for example, to the municipality, which will have to find funds for the operation of this object. As a result, the consumer (citizen) will again be at the extreme, who will consume “rusty” water from the heating supply system, freeze in winter due to lack of heating and suffer from heat during the transition period (October, April) during overheating, carrying out vent control, which leads to colds from - for drafts.

1.2. Create specialized organizations that would deal with the entire chain: from design and installation to commissioning and maintenance of modern heat supply systems. For this purpose, it is necessary to carry out targeted work on training specialists in the field of energy saving.

2. When designing these systems, it is necessary to closely link together all the elements of heat supply systems: heating, ventilation and hot water supply, taking into account not only the requirements of SNiPs and SP, but also considering them from an angle from the point of view of operators.

3. Unlike outdated, traditional systems, modern systems require maintenance, which can only be carried out by specialized organizations with special equipment and highly qualified specialists.

BIBLIOGRAPHY

1. On the practice of using two-pipe heating systems// Engineering systems. ABOK. North-West, No. 3, 2002.

2. Lebedev hydraulics of HVAC systems // ABOK, No. 5, 2002.

3. Ivanov operation of plate heaters in the conditions of St. Petersburg // Heating News, No. 5, 2003.

> Documentation Modern heat supply systems (HSS) are quite complex technical systems with a significant number of elements varied in their functional purpose. characteristic. The work 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. An analysis of the main factors influencing the operation of the heat supply system is presented. Recommendations are given for choosing the optimal heat supply system. Russia inherited from the USSR a high level of centralized heat supply. At the same time, combined generation of heat and electricity was ensured. Combustion products were effectively cleaned and dispersed. But at the same time, existing centralized heat supply systems have significant drawbacks. These include overheating of buildings during the transition period, large heat losses from pipes, and disconnection of consumers during maintenance work. The state of heat supply systems in Russia is critical. The number of accidents in heating networks has increased fivefold compared to 1991 (2 accidents per 1 km of heating networks). Of the 136 thousand km of heating networks, 29 thousand km are in disrepair. Heat losses during coolant transportation reach 65%. That is, every fifth ton of standard fuel is used to heat the atmosphere and soil. Reduced funding and poor quality of relaying are worsening the situation. There is a contradiction, which lies in the fact that manufacturers include excess heat losses in tariffs and require payment for the heat produced, rather than for the heat consumed. In addition, consumers must pay according to the area of ​​the heated room, that is, regardless of the quantity and quality of the coolant. Currently, there is extremely great interest in decentralized heat supply. 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 thermal power plants and large boiler houses. In Russia, several dozen multi-storey buildings with apartment-by-apartment heating of up to five floors are in operation. The number of floors is limited by current building codes. As an experiment, the State Construction Committee and the Main Directorate for Promotion of the Ministry of Internal Affairs of the Russian Federation allowed the construction of 9-14-story buildings with apartment heating in the Smolensk, Moscow, Tyumen, and 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 area, where, as a rule, they are installed. Smoke removal during apartment-by-apartment heat supply is associated with the construction of external and internal flue ducts made of corrosion-resistant metal with thermal insulation that prevents condensation during periodic operation of heat generators during the transition period of the heating season. In high-rise buildings, draft problems arise on the lower floors (highest draft) and upper floors (weak draft). When using decentralized heat supply, basements and staircases are not heated, which leads to freezing of the foundation and a decrease in the service 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 surrounding apartments. A certain type of “energy parasite” is created. The environmental parameters of wall-mounted boilers are normal, and the NOx emission rate ranges from 30 to 40 mg/(kWh). At the same time, wall-mounted boilers have combustion product emissions dispersed in a residential area at a relatively low height of chimneys, which has a significant impact on the environmental situation, polluting the air in a residential area. In connection with the above-mentioned disadvantages and advantages of centralized and autonomous heat supply systems, the question immediately arises: where and in what cases is autonomous heat supply most appropriate, and in which is 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 boiler houses. Option IV - apartment-by-apartment heat supply. In the first option, a centralized heat supply system has been developed, where the heat source is a boiler room, from which a two-pipe heating network is provided to the central heating point, and after the central heating point, a four-pipe installation for heating and hot water supply. In this case, gas is supplied to the boiler room. In the fourth option, a local heat source is installed in the apartment, which ensures the supply of coolant to the heating and hot water supply systems. This scheme proposes a 2-stage gas supply system. 1st stage – medium pressure gas pipeline, which is laid inside the block (a cabinet control point is installed in each house). 2nd stage – low pressure intra-house 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 source of heat, from which a two-pipe installation is provided from the AIT to the IHP (Individual Heating Point), and from the IHP there is a four-pipe installation for heating and hot water supply. In this case, gas is supplied to the AHS (autonomous heat sources) through medium-pressure gas pipelines. In the third case, roof boiler houses are used as a heat source, relatively low power(from 300 to 1000 kW), which are located directly on the roof of the building and satisfy the heat demand for heating, ventilation and hot water supply. The gas pipeline to the boiler room is supplied through the outer wall of the building openly in places that are convenient for maintenance and exclude the possibility of damage. Options for heat supply systems are presented in Fig. 1. Technical decisions on heat supply based on several options should be made on the basis of technical and economic calculations, the optimal option of which is found by comparing possible solutions. The most expensive heat supply option is the first - centralized heat supply from the boiler house. With such a system, most of the costs come from heating network taking into account the central heating point, which is 63.8% of total cost systems as a whole. Of this, the laying of heating networks alone accounts for 84.5%. The cost of the heat source itself is 34.7%; the share of gas networks, taking into account hydraulic fracturing and gas distribution stations, accounts for 1.6% of the total amount for the system. The fourth option (with apartment-by-apartment heat supply) is only 4.2% cheaper than the first (Fig. 2). This means that they can be accepted as interchangeable. If in the first option the majority of the costs are made up of heating networks, then with apartment-by-apartment heat supply - the heat source, that is, wall-mounted boilers - 62.14% of the total cost of the system as a whole. In addition, with apartment-by-apartment heat supply, the costs of laying gas networks increase. It is worth paying attention to two other options. These are roof boiler houses and automatic heating units. From an economic point of view, the most profitable option is the second option, that is, centralized heat supply from AIT (autonomous heat sources). In this option, most of the costs fall on heating networks, taking into account ITP, which amounts to 67.3% of the total cost of the system as a whole. Of this, 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 gas distribution stations, accounts for 6.7% of the total amount for the system. The costs of laying heat supply system pipes depend on the length of the heating networks. Consequently, bringing a gas-fired heat source closer to the consumer by installing attached, built-in, roof-top and individual heat generators will significantly reduce system costs. In addition, statistics show that most of the failures of the centralized heat supply 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 heat supply in Russia is of great social importance, increasing its reliability, quality and efficiency is the most important task. Any disruptions in the provision of thermal energy to the population and other consumers 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, to increase the reliability of laid heat pipelines, it is necessary to use pre-insulated ductless pipes with polyurethane foam insulation in a polyethylene sheath (“pipe in pipe”). The essence of the housing and communal services reform should not be an increase in tariffs, but the regulation of the rights and obligations of the consumer and heat producer. It is necessary to agree on regulatory issues and develop a technological regulation framework. All conditions for economic attractiveness for investment must be created. Rice. 1. Schematic diagrams of heat supply systems Fig. 2. Schedule of reduced costs Literature 1. Economics of heat and gas supply and ventilation: Textbook. 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. Proceedings of the International Scientific and Technical Conference “Theoretical Foundations of Heat and Gas Supply and Ventilation”, November 23 – 25, 2005, MGSU The article discusses the issues of optimizing the functioning parameters of a 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 optimal parameters for the functioning of the heat supply system depending on external influences. Modern heat supply systems (HSS) are quite complex technical systems with a significant number of elements that are varied in their functional purpose. Characteristic of them is the commonality of the technological process of producing steam or hot water in a boiler house using the energy released by burning fossil fuels. This allows in various economic and mathematical models to take into account only the final result of the operation of the heating system - the supply of heat Qpot to the consumer in thermal or cost indicators, and consider the costs of producing and transporting heat as the main factors determining the value of Qpot: consumption of fuel, electricity and other materials, wages, depreciation and repair of equipment, etc. A review of thermodynamic analysis methods allows us to conclude that it is advisable to optimize the operating parameters of STS using exergy methods. These methods include the method of thermoeconomics, which successfully combines both thermodynamic and economic components of STS analysis. The main idea of ​​the thermoeconomics method is to use, to assess changes occurring in the energy system, some generalized thermodynamic characteristic that ensures the final beneficial effect. Considering that energy can be transferred in the HTS 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 is transferred from a heating source with a temperature Th to the environment with a temperature Toc: where hT is the thermal efficiency of a direct reversible cycle. When using the thermoeconomic method, changes occurring in the main exergy flow are analyzed, which ensures a useful final effect (in the case of STS analysis, indoor air exergy). At the same time, exergy losses arising during the transmission and conversion of energy in individual elements of the STS are considered and taken into account, as well as the economic costs associated with the operation of the corresponding elements of the STS, the presence of which is determined by the selected scheme. Analysis of the changes undergone only by the main exergy flow, which provides a useful final effect, makes it possible to present the thermoeconomic model of the STS in the form of a number of separate zones connected in series. Each zone is a group of elements that are relatively independent within the system. Such a linearized representation of the technological scheme of the STS significantly simplifies all further calculations by excluding individual technological connections from consideration. Thus, the method of thermoeconomics, including the thermoeconomic model of the STS, makes it possible to optimize the operating parameters of the STS. Based on the method of thermoeconomics, a thermoeconomic model of STS is being developed, the schematic diagram of which is shown in Fig. 1, where a water heating system with artificial water circulation is connected to the heating network according to an independent circuit. Rice. 1. Schematic diagram of STS In Fig. Figure 1 indicates the STS elements taken into account when developing the model: 11 - 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 the 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 – charging pump with electric motor; 31 - heating devices. When constructing a thermoeconomic model of the STS, the energy cost function 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 are made: · the change in pressure losses in heat pipelines during transportation of the coolant is 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 pipes (pipes in the boiler room) and heat pipes of the heating system (internal pipes) as a result of heat exchange between the coolant and the environment are considered constant, independent of the operating mode of the heating system; · exergy losses caused by water leaks from the network are considered constant, independent of the operating mode of the STS; · the heat exchange of the working fluid with the environment that occurs in the boiler, tanks for various purposes (decarbonizers, storage tanks) and heat exchangers through their outer surface washed by air is not taken into account; · heating the coolant by transferring additional heat from the flue gases to it, as well as heating the air entering the furnace with the heat of the exhaust gases, are not optimized in the case under consideration. It is believed that the main part of the heat of flue gases is used to heat 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 exhaust flue gases Tyg in the steady state operation of the boiler unit is taken equal to 140 ° C; · heating of pumped water in pumps is not taken into account. Taking into account the stated starting points and the assumptions made, the thermoeconomic model of the STS, the principle diagram of which is shown in Fig. 1, can be represented in the form of three series-connected zones 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 a water-to-water heat exchanger of the local heating point 211 and a circulation pump with an electric motor 221, and zone 2(2) includes a raw water heater 212, a raw water pump with an electric motor 222 and a make-up pump with an electric motor 232. Zones 2(1 ) and 2(2) represent a parallel connection of individual elements of the thermoeconomic model of a multi-purpose STS, providing heat supply to objects with different temperatures. Zone 3 includes heating devices 31. Exergy is supplied from an external source through the control surface to various zones of the thermoeconomic model of the STS: e11 - to drive the electric motor of the fuel pump (compressor); e13 - for driving the electric motor of the network pump; e22(1) - to drive 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 charging 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 convertible into any other type of energy. Fuel is supplied from an external source, the consumption of which is vt, and the price is Ct. Since thermal processes occupy the main place in the functioning of the STS, the variables to be optimized are those that make it possible to develop a thermoeconomic model of the STS and provide a relatively simple determination of the temperature conditions for the processes taking place in the STS. When solving the problem of static optimization of the STS, taking into account the assumptions made and the accepted notations, the amount of energy costs, including the costs of electrical energy and fuel, is determined by the dependence: where t is the operating time of the STS. The consumption of electrical energy to drive pump motors and fuel consumption depend on the operating mode of the heating system, and therefore on the temperature pressure in the heat exchangers, the temperature of the exhaust gases and the range of changes in coolant temperature. Therefore, the right side of expression (2) is a function of the selected optimized variables. Consequently, the amount 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 energy cost function with respect to the optimized variables are equal to zero. This approach is valid if all optimized variables are considered as independent and the problem is reduced to determining the unconditional extremum. In reality, these variables are related to each other. 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 thermoeconomics method during research makes it possible to simplify this task. As shown in Fig. 2, the thermoeconomic model of the STS is presented in the form of a series of zones connected in series, 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 in general view are presented as follows: The equations included in system (4) refer to different zones of the thermoeconomic model, the connection between which is carried out by the main exergy flow. The exergy flow connecting individual zones is presented in the form of 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 describing its change. The presence of connections between the optimized variables forces us to consider the optimization of energy costs as a problem of optimizing a function of several variables in the presence of constraints such as equalities (connection 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 undetermined multipliers. Application of the method of indefinite Lagrange multipliers reduces the problem of finding the conditional extremum of the original energy cost function (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 operating parameters of the STS is written as follows: When comparing the expression for energy costs (2) and for the Lagrangian (6), taking into account dependencies (4) and (5 ) one can be convinced of their complete identity. To find the extremum conditions, partial derivatives of the Lagrange function (6) must be taken with respect to all variables (both optimized and additional ones introduced by the coupling equations) and set equal to zero. Partial derivatives with respect to exergy flows connecting individual zones of the thermoeconomic model ej allow one to calculate the values ​​of the Lagrange multipliers lj. Thus, the partial derivative with respect to e2(1) has the following form: System of equations (8) establishes a connection between energy dissipation and energy costs in each zone of the thermoeconomic model for certain values ​​of economic indicators Tsel, Tst, l2(1), l2(2), l3. The values ​​l2(1), l2(2), l3 in the 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. Solving system (8) taking into account equations (7) allows us to determine the necessary conditions for finding the minimum of the Lagrangian (6). To solve systems of equations (7) and (8), expressions (4) and (5), written in general form, must be presented in the form of detailed analytical relationships, which are components of a mathematical description of the processes occurring in individual elements of the STS. Literature Brodyansky V. M., Fratscher V., Michalek K. Exergetic method and its applications. Under. ed. V. M. Brodyansky - M.: Energoatomizdat, 1988. - 288 p.

Baibakov S. A., engineer at JSC VTI

1. Current situation and problems.

Due to the peculiarities of climatic conditions, uninterrupted supply of thermal energy to the population and industry in Russia is an urgent social and economic problem. According to various sources, approximately 2020 million Gcal were produced for heat supply purposes in 2000. Over 45% of the total consumption of all types of fuel was spent on this, which is approximately 2 times more than fuel consumption for the needs of the electric power industry and corresponds to the fuel intensity of all other sectors of the economy.

Currently, heat supply to consumers in large settlements is mainly produced and will be produced in the future from sufficiently powerful centralized heating systems (DHS), which have large thermal power plants or district boiler houses as heat sources.

A significant part of the heat energy needs in our country, and especially in cities with a high concentration of heat loads, is traditionally met by large central heating systems based on steam turbine CHP plants with heating turbines of various capacities, i.e. There is a widespread use of district heating, the use of which objectively allows for significant savings in fossil fuels. Thus, the combined generation of thermal and electrical energy in Russia from various sources allows saving from 20 to 30% of fuel compared to separate generation.

In modern conditions, the development of district heating and heat supply systems based on it has begun to experience competition from decentralized schemes and separate generation of thermal and electrical energy, due to the following circumstances.

The efficiency of power plants with condensing turbines has increased significantly and reaches 40 - 43%. At the same time, it was possible to increase the efficiency of heating boiler houses, the value of which exceeds the efficiency of power boilers of thermal power plants, and the efficiency of using fuel from small boiler houses can practically reach 100%. All this leads to a decrease in relative fuel economy during district heating. In addition, the development of district heating requires significant initial costs, and the payback period for the creation of large thermal power plants is about ten years. In modern economic conditions, this situation, taking into account the mobility factor, objectively leads to a transition to heat supply from quick-payback, automated and highly economical boiler houses of various capacities, including rooftop and factory-ready house boiler plants, despite the fact that the specific capital costs for such boiler houses are much higher similar indicator for thermal power plants.

One of the main problems with the traditional DHS scheme is the factor of reliability of heat supply. As already noted, the accepted location of base and peak heat sources, the development of heat supply modes and the values ​​of network water parameters were determined without taking this factor into account. As a result, the following situation arose.

The concentration of thermal power and the radial-dead-end structure of heating networks have very limited capabilities for reserving the thermal power of heat sources. Emergency heat transfers can be carried out mainly through the end sections of heating networks that have low throughput. In accordance with this, emergency situations at the heat source or at the head sections of heating networks can lead to a significant and long-term reduction in heat supply to consumers.

To increase the reliability of heat supply at the heat source, it is possible to use backup heat-generating equipment (steam heat exchangers) with steam supplied from station steam collectors or from extractions with higher steam parameters and sectioning the collectors of cogeneration plants of thermal power plants.

In heating networks, increased reliability of heat supply is ensured different ways redundancy and duplication of pipelines, which leads to an increase in the cost of heating networks and the complication of their schemes. With long main heating networks, increased reliability is ensured by sectioning main pipelines, laying several lines of pipelines with a smaller diameter and organizing jumpers between them. In addition, it is planned to connect consumers to jumper pipelines between adjacent mains, thereby providing the possibility of two-way heat supply.

Another factor that negatively affects the reliability of heating networks is the use of a fairly high temperature schedule of 150/70 o C. With this schedule, per 1 o C change in the outside air temperature there is approximately a 3.0 o C change in the temperature of the network water in the supply line. Accordingly, with possible relatively rapid intraday changes in weather conditions associated with an increase or decrease in air temperature during the heating period by 7-10 o C, a change in the temperature in the supply line by 21-30 o C is required. At the same time, changes in air temperature and, accordingly, water in pipelines are usually cyclic in nature.

In these conditions, operating experience as a measure to improve reliability involves the use of cutting the temperature curve to a maximum temperature of 120-130 o C, which leads to a lack of heat supply for heating. When installing load regulators (water temperature in the heating circuit) at heating points of consumers with an independent heating connection circuit, the use of cutting the temperature curve can lead to a significant increase in water consumption in the heating network and a significant change (complication) in the hydraulic regime of the heating networks.

A decrease in the attractiveness of obtaining heat from heat supply systems using district heating leads to the disconnection of consumers and their transition to other sources of thermal energy. At the same time, production volumes are falling and heat tariffs for other consumers are increasing.

In order to increase the attractiveness of heat supply based on district heating, it is necessary to take organizational and technical measures to increase the reliability and efficiency of heat production and transport, allowing for thoughtful and comprehensive solutions to existing problems, taking into account the expected increase in heat loads of existing systems and deterioration of main equipment, and especially those installed at thermal power plants peak boilers.

At the same time, as follows from published materials on foreign experience in organizing heat supply, currently in European countries (Denmark, Germany) the creation of large centralized heat supply systems based on the parallel connection to a common heating network of several sources of varying power with combined heat production has become widespread. and electrical energy (Mini-CHP, PGU CHPP, GTU CHPP).

This approach is due to the significant fuel savings obtained by using district heating and the ability to most effectively solve environmental problems when burning fossil fuels. At the same time, the regulation of heat supply in the systems under consideration is carried out in accordance with the schedule of quantitative and qualitative regulation at a maximum design temperature in the supply line at the level of 110 - 130 o C. Normal operation of heat supply systems in these conditions is possible only under the condition of complete automation of thermal energy consumers.

2. Analysis of existing proposals for the structure and schemes of the central heating system.

Modern central heating systems are a complex engineering complex of thermal energy sources (main and peak) and heat consumers, interconnected by heating networks for various purposes and balances, having characteristic thermal and hydraulic regimes with given coolant parameters. The magnitude of the parameters and the nature of their changes are determined by the technical capabilities of the main structural elements of heat supply systems (sources, heating networks and consumers), economic feasibility and, to a large extent, the accumulated experience in creating and operating such systems.

Recently, close attention has been paid to increasing the efficiency of combined heat generation and heat supply systems based on it. Many authors and organizations have developed various proposals on possible directions for changing the structural diagrams of such systems. At the same time, we are not talking about the use of new equipment, such as the use of steam-gas cycles for district heating, which in itself makes it possible to increase the efficiency of heat supply, but rather about the development of non-traditional schemes for heat supply systems in general, in which the advantages of combined heat energy production are used to the greatest extent .

One of such proposals is the well-known proposal from the technical literature /1/ by Doctor of Technical Sciences. Andryushchenko A.I., the essence of which is the transition to a centralized supply of heat from thermal power plants only for hot water supply with its supply to heat consumption areas according to a single-pipe scheme. In this case, the heating load is provided by peak sources located directly in the areas of heat consumption with different compositions of heat-generating equipment and corresponding heating networks. The supply of water and heat from thermal power plants to two-pipe district heating networks is carried out in the form of their replenishment to compensate for direct water withdrawal for hot water supply in district networks, carried out according to an open scheme.

The use of such a central heating scheme makes it possible to increase the efficiency of combined generation by reducing the temperature of heat removal from the heating outputs of turbines with a stable annual load for heat supply.

However, heat supply systems with a similar structure can obviously be used in completely new construction, as well as in the reorganization of a heat supply scheme that involves the use of either a suburban CPP or a new CHPP with heat supplied to existing district heating networks, which use city block boiler houses as heat sources. Those. the use of the proposal under consideration requires a special organization of the system, characterized by the concentration of a significant load of hot water supply and the construction of heating networks for its transmission to areas of heat consumption.

The proposed scheme cannot be used for existing urban heat supply systems based on large thermal power plants based on the practical impossibility of transferring the hot water supply load to one of the sources. In addition, when using open hot water supply schemes, the need to create appropriate water treatment with high productivity and the availability of source water of a certain quality should be taken into account.

Several options for changing the connection schemes for peak sources in heat supply systems and the operating conditions of heating networks are given by the authors from the Ulyanovsk State Technical University in the monograph /2/.

Basically two proposals can be considered.

The first of them proposes to connect peak boiler houses at thermal power plants in parallel to network heaters and transfer the operation of heating networks to a lower temperature schedule using central quantitative or qualitative-quantitative regulation.

In this regard, it should be said that with modern automation schemes for heating points, a central change in water flow at the heat source is impossible, since water flow is determined by regulators at the heat consumer. In addition, the possibility of complying with restrictions on permissible water flows through turbine network heaters in the event of significant changes in flow rates in heating networks, which may require shutting down the heat supply turbines and operating them in a purely condensing mode, raises doubts.

In addition, for existing heat supply systems, a direct transition to a lower temperature schedule is also not possible, since with the same heat load, the significantly increased flow of network water cannot be passed through heating networks with the same pipeline diameters.

The second proposal considers the possibility of transitioning to complete decentralization of peak power installations of heat supply systems with its production directly from consumers. This proposal is also unlikely to be economically justified in terms of the total costs of the heat supply system, although, according to the authors, it allows for significant fuel savings.

So, it is proposed to use either electric heaters or house gas boilers as peak sources. All this together will obviously be much more expensive than the reconstruction of a peak water heating boiler house at a thermal power plant, since it will require relocation of either electrical networks or gas pipes. In addition, the use of electricity for heating purposes, as previous experience shows, allows one to obtain economic benefits only if there is an excess of cheap electricity produced, for example, by hydroelectric power plants.

The authors practically do not consider the operating modes of heating networks under the proposed schemes.

One of the latest proposals made by a group of authors from Belarus (Skoda A.N. et al.), which consists in switching heat supply from thermal power plants to three-pipe heating network schemes with separate heat supply for heating and hot water supply /3/. At the same time, at the thermal power plant, the hot water supply load is provided mainly through the use of the condenser heating bundle and the selection of the lower stage, and the heat supply for heating is produced from the upper heating extraction.

The proposed version of the heat supply system diagram has a number of advantages. The efficiency of the turbine increases due to the elimination of a purely ventilation passage and the generation of electricity from thermal consumption while reducing the parameters of heat removal from the cycle. At the same time, the operating modes of thermal heating networks are improved by stabilizing the hydraulic regime and making it possible to reduce the water temperature in the supply line at positive air temperatures in accordance with the heating schedule, due to the absence of the need to break the temperature schedule. The use of storage tanks for hot water supply, installed in areas of heat consumption, also makes it possible to have a stable hydraulic and thermal regime in the pipelines of the hot water supply system from thermal power plants.

For the above SCT scheme, it is necessary to install equipment for preparing water for hot water supply at the CHP plant, and in addition, the use of such a scheme in existing systems is practically impossible to implement, since almost all heating networks from the CHP plant require additional laying of pipelines for hot water supply networks. The proposed scheme can be considered as an option when creating new centralized heat supply systems.

The above works examine in detail mainly direct heat sources (cogeneration equipment of turbines and peak boiler houses) and increasing efficiency in heat production, but insufficient attention is paid to the conditions and operating modes of connected heating networks and heat consumers, as well as issues of creating integral systems based on the proposed options. This especially concerns the possibilities of using the above proposals for use in already established central heating systems with a traditional scheme.

However, the presence of the above problems with centralized heat supply and the possible increase in heat loads in cities will require raising the question of the feasibility of their reconstruction and modernization. At the same time, existing problems must be solved in a comprehensive manner, taking into account existing conditions and possible operating modes of heating networks and consumers.

3. Proposals for changing the schemes of existing central heating systems.

As the main directions for achieving the goals set above, one should first of all consider proposals that allow for the possible decentralization of heat sources and a reduction in the temperature schedule of heating networks.

For heat supply systems with a traditional structure, reducing the temperature schedule of heating networks is an expensive and difficult task. This is determined mainly by the possibilities of regulating the heat supply for heating at consumer heating points and the pipeline diameters adopted when designing heating networks.

Below we propose a possible option for changing the structure of currently operating central heating stations, the implementation of which will make it possible to ensure the fulfillment of the specified conditions at the lowest cost.

It is proposed to reconstruct the heat supply system, transferring peak heat sources from thermal power plants to areas of heat consumption. At the same time, the peak boilers at the thermal power plant that require reconstruction are dismantled, and new peak heat sources are equipped on the heating networks of all large outputs of the thermal power plant and are connected to existing mains at intermediate points. A schematic diagram of the heat supply system with such a transfer of peak sources is shown in Fig. 1, which also shows the initial diagram of the SCT (Fig. 1 a) with a traditional structure.

Hot water boilers can be used as peak sources, as well as various other types of heat generating equipment, including combined cycle power plants or gas turbine power plants. The choice of the type of peak source is generally determined based on the results of technical and economic calculations.

The transfer of peak sources to areas of heat consumption divides heating networks with connected consumers into two zones: the zone between the thermal power plant and the point of connection of the peak source (CHP zone); and the zone after the peak source (peak boiler zone). At the same time, different temperature (temperature curves) and corresponding hydraulic regimes can be maintained in both zones. As shown in Fig. 1, switching on peak sources via network water can be done either in series with the heating equipment of the CHP plant, or in parallel with the equipment of the CHP plant. Each connection scheme has its own advantages or disadvantages.

When connected in series, a large flow of water with a relatively high temperature in front of the source will pass through the peak source, which is important when using hot water boilers. This scheme provides for the supply of heat only to the peak source zone in the absence of the possibility of delivering thermal power to the CHP zone.

With a parallel connection, a reduced flow rate with the return temperature at the inlet passes through the peak source, but at the same time it is possible to supply water and heat to the heating networks of the CHP area, thereby providing the possibility of reserving the thermal power of the CHP. A mixing pump is installed at the peak source.

In real conditions, both parallel and series connection of peak sources can be used simultaneously. The choice of specific schemes is determined by the hydraulic characteristics of existing heating networks and the necessary backup conditions.

The proposed change in the structure of the heat supply system makes it possible to reduce thermal power, released directly from the thermal power plant to the power level of the turbine heating equipment. Under this condition, the existing water flow can be passed through existing pipelines without changing the diameter, which makes it possible to switch to a lower temperature schedule in the CHP area.

The length of heating networks after the peak source is comparatively less than the total length of the network of the original system, which allows for large pressure (pressure) losses, provided that the same available pressure is ensured at the most distant consumers. In accordance with this, in networks after the peak source it is also possible to switch to a reduced schedule with increased flow rates of network water.

The proposed structural diagram of the central heating system leads to the decentralization of heat sources with the possibility of their mutual redundancy and at the same time makes it possible to switch to a lower temperature schedule in heating networks, which should ensure increased reliability of heat supply. The transition to the proposed structural scheme of the central heating system will only require bringing the automation of consumer heating points to the required level.

In addition to these advantages, the proposed scheme allows you to increase the connected load and power of the heat supply system in certain areas of the heating network by increasing the power of peak sources, without changing the diameters of the pipelines of the rest of the network and the characteristics of other heat sources included in the central heating system.

It should be noted that the hydraulic and thermal conditions of heating networks and heat sources, among other conditions, also depend on the location of the connection of the peak source to the heating network, i.e. from removing the connected peak source from the thermal power plant.

As an example of determining the indicators of the modes and assessing the main conditions for the reconstruction of the central heating system, the required parameters and operating modes were considered when changing the layout of the centralized heat supply system with a conditional design heat load of consumers of 1 Gcal/h.

The initial heating network is connected to consumers only with a heating load at a design temperature in the premises of +18 o C. Under these conditions and the temperature schedule of the traditional scheme of 150/70 o C, the water consumption in the network is constant and equal to 12.5 t/h.

It was assumed that the heating coefficient for the original traditional scheme is 0.5, i.e. half of the design load of the system is covered from the turbine heating outputs. The other half is provided by the peak boiler room. The graph for covering the thermal load of the heating supply system depending on the outside air temperature (relative heating load), adopted based on the condition of the maximum heat load of the heating turbines of the CHP plant, is shown in Fig. 2

Rice. 2 Schedule for covering the thermal load of the heating system.

For preliminary analysis, we will assume that the connection of the heat load is distributed evenly over the heating network, which is one dead-end main line of varying diameter along the length of the network. The total relative length of the network is 1.

Schemes of the initial heat supply system and the system after transferring the peak source (peak boiler house) to the heat consumption area are shown in Fig. 3. In the same fig. the following are shown symbols main parameters of SCT modes.

A. Initial (traditional) SCT scheme

b. Transformed SCT circuit

Rice. 3 SCT conversion diagram and symbols.

Legend:

1 - Cogeneration equipment of CHP

2 - Peak source (peak boiler room)

To assess changes in the hydraulic regimes of the heat supply system, it was assumed that in the heating network with a traditional scheme there is a linear change in pressure along the length of the pipelines. In this case, the relative available pressure at the thermal power plant under the traditional scheme is equal to 1, and the stability of the network (the ratio of the available pressure at the subscriber input to the available pressure at the thermal power plant) is 0.2, i.e. the available pressure at the last consumer is equal to 20% of the developed pressure at the thermal power plant.

Based on the results of the calculations, it will mainly be shown technical feasibility implementation of the transfer of the peak source to the heat consumption area and the recommended operating modes of the heat supply system. It should also be taken into account that the choice of basic parameters and solutions (power ratio, location of the peak source, accepted temperature schedules, etc.) is obviously determined not only by purely technical, but also by technical and economic conditions. The proposed material does not consider technical and economic conditions.

For the new heat supply system, the same schedule for covering the total thermal load of the system was adopted as for the original network, which is shown in Fig. 2, i.e., the peak source provides half the load under design conditions and the heating coefficient for the central district heating system as a whole remains equal to 0.5.

We will assume that for consumers connected to the network after the transferred peak source (PC zone), a heating temperature schedule of 130/70 o C is accepted. For consumers in the CHP zone, the calculated temperature schedule is accepted lower based on the possibility of turbine heat extraction and equal to 120/70 o WITH.

Provided that consumer heating points are automated, the temperature in the return line of the network will not change during reconstruction and will remain equal to this temperature for the original heating network.

The possible point of connection of the peak source to the heating networks under the accepted conditions is determined by the hydraulic mode of the original system and the conditions of the resulting hydraulic modes when transferring the peak source, for which the requirement of ensuring the previous available pressures at the connected consumers must be met.

As shown by the calculations of the thermal-hydraulic modes of the transformed heat supply system, the point of connection of the peak source closest to the thermal power plant, provided that the specified available pressures are provided at the connected consumers, is 60% of the total length of the original heating network, i.e., it is removed by 0.6 relative units of the total length of the network from the thermal power plant. At the same time, the estimated heat load of consumers in the CHP zone will be 0.6 Gcal/h, and in the peak boiler zone 0.4 Gcal/h.

For the central heating system, after reconstruction, the original schedule for covering the total thermal loads of the system is preserved. However, the load coverage graphs for the CHP and peak boiler zones for the conditions of Fig. 2 are more complex.

The graph for covering the thermal loads of consumers in the CHP zone depending on the relative heating load is shown in Fig. 4, graph of coverage of thermal loads of consumers in the peak boiler zone - in Fig. 5

In Fig. Figure 4 shows graphs of changes in the load of consumers in the CHP zone and heat supply from the CHP. A graph of heat supply from the thermal power plant to the peak source zone (to the PC zone) is also given. The latter, at relative loads greater than 0.83 (at low outside temperatures), has negative values, which indicates the need to supply heat to the CHP zone from a peak source.

Figure 5 shows graphs of the load of consumers in the PC zone and the heat supply from the peak source. In the same fig. a graph of heat supply to the PC zone from the thermal power plant is also shown, which at relative loads greater than 0.83 has negative values, indicating, as already noted, that heat is supplied from the peak source to the thermal power plant zone.

Temperature graphs of the central heating system for the CHP zone and the peak boiler room are shown in Fig. 6, which also shows the temperature graph of the original MCT for comparison.

As follows from Fig. 6, the temperature graph from the CHP of the converted heat supply system has a complex dependence on the outside air temperature. The maximum temperature under design conditions corresponds, as indicated earlier, to 120 o C, and the minimum temperature of network water from the thermal power plant at the start (end) of the heating period is taken to be 70 o C. The graph under consideration has a break point at a relative load equal to 0.5, corresponding to the peak switching point boiler room The temperature at this point determines highest consumption water in the pipelines of the CHP zone, transferred to the PC zone, which determines the most intense hydraulic regime of the CHP zone and the heat supply system as a whole. The temperature at the break point was determined based on the conditions for ensuring the necessary hydraulic conditions for the connected consumers at the accepted connection point of the portable peak source.

It should be noted that the temperature level in the supply line from the heating part of the thermal power plant determines the efficiency of the combined generation of thermal and electrical energy, and the lower it is, the higher the specific combined production.

Corresponding to the above data on temperatures in various parts of the heating system circuit at the accepted point of transfer of the peak source, graphs of water consumption depending on the relative heating load (outside air temperature) in various sections of the heating system circuit are shown in Fig. 7. For comparison, the figure shows the required flow rate of network water from the thermal power plant for the original heat supply system at a temperature curve of 150/70 o C.

As follows from Fig. 7, the water consumption from the thermal power plant in the reconstructed heat supply system is significantly lower than the initial value of 12.5 t/h and increases as the outside air temperature decreases from 6.5 to 10.0 t/h. The water flow through the peak source with a decrease in air temperature first decreases from 4.1 to 3.6 t/h and then increases to a maximum value under design conditions equal to 8.7 t/h.

Just as during heat supply, in the reconstructed central heating system there are water flows between the CHP zone and the PC zone. Water consumption by zones is shown in Fig. 8 and 9.

Figure 8 shows a graph of the total water consumption for consumers in the CHP zone, a graph of water consumption from the CHP and a graph of water supply to the CHP zone from the peak source. The latter has negative values ​​for relative loads less than 0.83 and shows that at these relative loads there is a supply of water from the pipelines of the CHP area (from the CHP) to the peak source.

In Fig. Figure 9 shows graphs of water consumption in the peak source zone, as well as graphs of water consumption for consumers in the PC zone, water consumption through the peak source and water consumption from the thermal power plant to the PC zone. In this case, the maximum value of water flow supplied from the thermal power plant to the peak source is noted at a relative load equal to 0.5 and corresponding to the switching point of the peak boiler house. The value of this flow rate is 3.3 t/h.

Based on the above data on the calculated hydraulic mode of the original network and the conditions for connecting the thermal load, calculations of hydraulic modes were carried out and piezometric graphs of the reconstructed network were constructed for characteristic relative loads (outside air temperatures), shown in Fig. 10.

In Fig. piezometric graphs are shown at the design temperature of the outside air, at the most intense hydraulic mode corresponding to the relative load at the point at which the peak source starts operating and, for comparison, a piezometric graph of the heating network of the original heat supply system. As follows from Fig. 10 requirements for hydraulic modes for the converted central heating system (requirements for available pressures of connected consumers) are met in all modes.

The obtained calculation results show the possibility of technical implementation of the proposed change in the central heating system scheme, while the results are presented for one of possible options. For the accepted conditions of changing the scheme, the costs of pumping coolant increase and the indicators of specific combined heat energy production deteriorate, since heat is released from the heating equipment of the CHP plant at higher temperatures in the supply line of the heating network of the CHP zone than for the original SCT circuit. However, for the modified design of the heat supply system, the level of maximum temperatures in the supply line will decrease, which, together with the decentralization of heat sources, will increase the reliability of heat supply with a slight decrease in its efficiency.

The technical and economic indicators of the above-considered option for reconstructing the central heating system for given design temperature schedules are determined by the accepted point of connection of the peak heat source to the heating network. Thus, removing the connection point of the peak source from the thermal power plant leads to an improvement in the performance of hydraulic modes, namely, to an increase in the available pressures in the heating network. This circumstance makes it possible to either increase the water flow from the thermal power plant when the temperature in the supply line of the thermal power plant zone decreases, thereby improving the performance of the combined production of thermal and electrical energy, or to reduce the available pressures at the thermal power plant and the peak source, reducing the additional energy consumption for pumping the coolant. In this case, one should also take into account the change in heat losses in heating networks associated with changes temperature regime heating networks

The choice of the main parameters of the variable SCT scheme is the result of technical and economic optimization calculations and is not considered in the proposed material.

4. Conclusions.

1. Existing developed centralized heat supply systems based on large urban thermal power plants with a traditional layout require reconstruction, both in terms of the equipment used and in the structural diagrams. Such reconstruction should lead, first of all, to increasing the reliability of heat supply and providing opportunities to increase the connected load.

2. The proposals for changing the schemes of heat supply systems given in modern technical literature give rise to a number of comments. Most of these proposals make it possible to increase the efficiency of using combined generation, but are practically of little use for existing central district heating systems due to the significant costs of their implementation, associated mainly with heating networks. Other proposals require a comprehensive analysis and additional calculations for heat supply modes and coolant parameters at various points in the circuits with determination of the total costs of creating and operating such systems.

3. The scheme proposed in the article for the reconstruction of traditional heat supply systems, associated with the transfer of peak sources to the area of ​​heat consumption and their connection to existing heating mains, is technically feasible and makes it possible to increase the reliability of heat supply by improving backup conditions and switching to lower temperature schedules. In this case, there is no need to re-wire heating networks, but only to bring the automation of consumer heat load connection circuits to the modern level.

Bibliography

1. Andryushchenko A.I. Combined heat supply systems. // “Thermal power engineering”. 1997. No. 5. pp. 2-6.

2. Sharapov V.I., Orlov M.E. Technologies for ensuring peak load of heat supply systems. M.: Publishing House “Heat Supply News”, 2006.-208 p.; ill.

3. Skoda A. N., Skoda V. N., Kukharchik V. M. Improvement of combined heat supply technologies. "Electric stations". 2008. No. 10. From 16-17.

The heating season in Russia lasts about seven months. For owners of private houses and those who are just planning to become one, the issue of efficient heating of the premises becomes a difficult task that is not so easy to solve. Let's try to figure out what modern heating systems in a private home are.

Most often, water or various antifreeze liquids that circulate through pipes are used for heating. The liquid is heated using gas boilers, which can operate on liquid, solid and gas fuels. Recently, electrode and induction boilers have been used as heating elements.

Water heating is popular due to the availability and efficiency of the coolant among owners of cottages and other suburban housing. The water system is easy to install yourself. The positive thing is that the volume of water in the system remains constant.

The disadvantages of water heating are the long time it takes to warm up the room, possible leaks and pipe ruptures. Do not turn off the water system in winter, as the water will freeze and burst the pipes.

Progressive heating systems

The design of modern heating systems for private houses is fundamentally different from traditional heating methods. Heating technology is developing rapidly every year. The equipment is being improved and becomes more efficient.

New energy sources are emerging that meet the requirements for protecting the natural environment and the general comfort of equipment operation.

An innovative development of Russian scientists is the PLEN infrared heating system. It consists of the thinnest polymer film and a resistive heating element made of carbon filaments.

PLEN emits the thermal component of sunlight, which is absorbed by the floor, ceiling, furniture and creates a comfortable room temperature.

Characteristics

The maximum surface temperature of this structure is 60°C, but to create the most comfortable conditions in the house, 30° - 40°C is sufficient.

PLEN can be laid over the entire surface of the base of the room, covering it with laminate or any other type of covering. If you mount the system on the ceiling, you will get a feeling of warmth and comfort like from the sun. It is also possible to attach the structure to the walls, but its effectiveness will suffer.

One of the advantages of a film heater is the absence of liquid coolant. This eliminates the need to install complex systems, leaks, and freezing of liquids. In addition, film heating systems have a number of other advantages:

• do not dry the air;
• there are no intense heat flows;
• do not create convective currents;
• fireproof;
• easy to install;
• completely safe for humans and the environment.

Another argument in favor of PLEN for a country house is many years of research by scientists. They proved that long-wave infrared radiation at moderate power has a beneficial effect on the human body.

The main disadvantage of an infrared heating system is its high cost. For device heating system For the entire house, you will have to make serious financial investments, which will not pay off quite soon.

Geothermal systems

An innovation in heating a private home is the extraction of heat from the ground, which is located in the local area. For this, a geothermal installation is used. Its design consists of a heat pump operating on the principle of a refrigerator, only for heating.

A shaft is created near the house where it is necessary to place a heat exchanger. Through it, groundwater will flow into the heat pump and release heat, which will be used to heat the building.
When heating a country house, antifreeze is used as a coolant. For this purpose, a special tank is installed in the mine.

It is very easy to use thermal energy, the source of which is sunlight. The latest country house heating systems powered by solar energy are a collector and a reservoir.

The structure of the tubes that make up the collector reduces heat loss to a minimum. Based on the design features, solar collectors There are vacuum, flat and air.

They must be placed as high as possible.

Nuances

This type of heating is suitable only for warm regions of the country where the bright sun shines at least 20-25 days a year. Otherwise, additional heating systems must be installed. Another disadvantage of solar panels is the high cost and short service life of the batteries needed to store electricity.

Hydrothermal systems

If your country house is located next to an ice-free body of water, then the necessary heat energy can be obtained from the water.

To do this, a heat exchanger probe is placed at the bottom of the reservoir, and a heat pump is installed in the house. The larger the probe size, the more efficient the hydrothermal installation.

Air systems

In warm climates, an air-to-air system can be used. The simplest types of such heat pumps are inverter air conditioners. They are installed like regular air conditioners. The efficiency of their work decreases at sub-zero temperatures, and at -30°C and below it is reduced to zero.

Wind energy has long been used to generate electricity. But it can also be used to heat suburban housing. Scientists have created a gearless wind power generator that is mounted on a vertical axis of rotation on the roof of a house. To reduce noise during operation of the structure, the axle must be equipped with a vibration isolator. An electric water heater and a heat accumulator are placed in the basement.

This device is quite difficult to manufacture, has a large size and weight. It is long and difficult to install. To obtain maximum wind energy, it is necessary to build a high enough tower.

Advantages and disadvantages

The undoubted advantage of this type of heating is its environmental friendliness. Extracting energy from wind does not cause any damage to the environment. In addition, this energy is absolutely free, and the costs of manufacturing and installing the equipment are relatively low.

Despite the undoubted advantages, this heating method country houses is not popular, which is due to the variability of wind strength and speed.

Electrical space heating refers rather to traditional heating methods that have been modernized in recent decades. Electrical appliances are easy to use, convenient and reliable. They have long been used for local heating.

To evenly heat the entire area of ​​a room using electricity, heated floors are used. This system is convenient for use in a country private house.

Warm floor system

Underfloor heating technology is a convenient and economical system for heating a room. Modern installations use advanced materials. Lightweight and durable polymer materials are used for the manufacture of pipelines.

The basis of a warm electric floor is a heating cable. The main thing in this type of heating is the quality of the cable, on which the efficiency of the system and its service life depend.
Warm floors using water do not emit harmful substances or electromagnetic radiation. Water is a cheap and heat-intensive coolant. A pipeline network through which the liquid flows is installed between the base and the floor covering. Compared to the electric "warm floor" system, this type of heating is much cheaper.

The energy supply policy pursued in recent years involves a transition to renewable energy sources. Increasingly, not gas and coal are used to produce electricity, but sun, wind, and water energy. These are environmentally friendly energy sources that do not pollute the environment with emissions and discharges.

Modern heating systems are based on various heating methods, which allows you to choose the most suitable option for your country house. Technologies proven over the years will ensure not only effective heating of rooms, but also independent temperature control in each room, fuel efficiency, automatic and remote control.

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

Classic heating systems

The classic type is boiler heating with liquid coolant. Taking heat from the boiler, the coolant heats the radiators, which in turn release heat into the room using air convection. The boiler can use gas, electricity, diesel fuel or wood as fuel.

Some types of classic heating receive more advanced versions, turning into modern heating systems. For example, electric heating can be direct - energy is immediately converted into heat without the use of a boiler, coolant, complex system of pipes and radiators. Direct electric infrared heating does not have the disadvantages inherent in standard convection heating. Infrared rays heat physical bodies, not air. Heated air does not accumulate under the ceiling, heating the room occurs more quickly and evenly. Direct system electric heating Requires the least installation and maintenance costs.

Air heating also does not use an intermediate coolant. The air heated by the boiler immediately enters the heated room through the air ducts. 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, wood combustion occurs according to a complex pattern with the formation of flammable pyrolysis gas. The gas is burned in a separate firebox, resulting in an increase in the overall efficiency of the boiler.

The most important indicator of the efficiency of modern autonomous heating is the possibility of flexible automatic, program and remote control. Gas, electric and air heating can be most easily and effectively automated. 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 innovative category includes all energy-independent heating technologies that use renewable energy sources - solar radiation, wind and wave energy, heat pump, etc. Making modern heating systems for a summer house or cottage energy-independent today is still too expensive, technologically difficult and not always effective. But every year technologies are improving, bringing closer the possibility of organizing completely independent heating. Currently, non-volatile technologies are used to organize additional, backup and emergency heating.

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

Modern heating of a country house is characterized not only by efficiency and economy, but also by high performance characteristics. A professionally designed and installed heating system has a long service life and allows for quick maintenance, repair and updating of equipment.