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We reduce heat loss in the house. The concept of optimization of thermal and hydraulic modes of operation of heat networks

Each of the above sections has characteristic unproductive losses, the reduction of which is the main function of energy saving. Let's consider each section separately.

1.Plot for the production of thermal energy. existing boiler house.

The main link in this section is the boiler unit, the functions of which are the conversion of the chemical energy of the fuel into thermal energy and the transfer of this energy to the coolant. A number of physical and chemical processes take place in the boiler unit, each of which has its own efficiency. And any boiler unit, no matter how perfect it is, necessarily loses part of the fuel energy in these processes. A simplified diagram of these processes is shown in the figure.

There are always three types of main losses at the heat production site during normal operation of the boiler unit: with underburning of fuel and exhaust gases (usually no more than 18%), energy losses through the boiler lining (no more than 4%) and losses with blowdown and for the boiler house’s own needs ( about 3%). The indicated heat loss figures are approximately close to a normal, not new, domestic boiler (with an efficiency of about 75%). More advanced modern boilers have a real efficiency of about 80-85% and these standard losses are lower. However, they can further increase:

If the regime adjustment of the boiler unit with an inventory of harmful emissions is not carried out in a timely and high-quality manner, losses with underburning of gas can increase by 6-8%;
The diameter of the burner nozzles installed on a medium-sized boiler is usually not recalculated for the actual load of the boiler. However, the load connected to the boiler is different from that for which the burner is designed. This discrepancy always leads to a decrease in heat transfer from torches to heating surfaces and an increase in losses by 2-5% due to chemical underburning of fuel and exhaust gases;
If the surfaces of boiler units are cleaned, as a rule, once every 2-3 years, this reduces the efficiency of the boiler with contaminated surfaces by 4-5% due to an increase in losses with flue gases by this amount. In addition, the insufficient efficiency of the chemical water treatment (CWT) system leads to the appearance chemical deposits(scale) on internal surfaces boiler, significantly reducing its efficiency.
If the boiler is not equipped with a complete set of control and regulation means (steam meters, heat meters, combustion process and heat load control systems) or if the boiler unit control means are not set optimally, then this, on average, further reduces its efficiency by 5%.
If the integrity of the boiler lining is violated, additional suction of air into the furnace occurs, which increases losses with underburning and exhaust gases by 2-5%
The use of modern pumping equipment in the boiler house allows two to three times to reduce the cost of electricity for the boiler house's own needs and reduce the cost of their repair and maintenance.
A significant amount of fuel is spent on each "start-stop" cycle of the boiler. The ideal option for operating a boiler room is its continuous work in the power range determined by the regime card. The use of reliable shut-off valves, high-quality automation and control devices allows minimizing losses arising from power fluctuations and emergency situations in the boiler room.

The above sources of additional energy losses in the boiler house are not obvious and transparent for their identification. For example, one of the main components of these losses - losses with underburning, can only be determined using a chemical analysis of the composition of the exhaust gases. At the same time, an increase in this component can be caused by a number of reasons: the correct fuel-air mixture ratio is not observed, there are uncontrolled air suctions into the boiler furnace, the burner is operating in a non-optimal mode, etc.

Thus, permanent implicit additional losses only during the production of heat in the boiler room can reach a value of 20-25%!

2. Loss of heat in the area of its transportation to the consumer. Existing heating pipelines.

Usually, the thermal energy transferred to the heat carrier in the boiler room enters the heating main and follows to consumer objects. The value of the efficiency of this section is usually determined by the following:

Efficiency of network pumps that ensure the movement of the coolant along the heating main;
losses of thermal energy along the length of heating mains associated with the method of laying and insulating pipelines;
losses of thermal energy associated with the correct distribution of heat between consumer objects, the so-called. hydraulic configuration of the heating main;
coolant leaks that occur periodically during emergency and emergency situations.

With a reasonably designed and hydraulically adjusted heating system, the distance of the end user from the energy production site is rarely more than 1.5-2 km and the total loss usually does not exceed 5-7%. But:

the use of domestic powerful network pumps with low efficiency almost always leads to significant unproductive energy overruns.
with a large length of pipelines of heating mains, the quality of thermal insulation of heating mains acquires a significant impact on the magnitude of heat losses.
hydraulic adjustment of the heating main is a fundamental factor determining the efficiency of its operation. The objects of heat consumption connected to the heating main must be properly spaced so that the heat is distributed evenly over them. Otherwise, thermal energy ceases to be effectively used at consumption facilities and a situation arises with the return of part of the thermal energy through the return pipeline to the boiler house. In addition to reducing the efficiency of boilers, this causes a deterioration in the quality of heating in the most remote buildings along the heating network.
if water for hot water supply systems (DHW) is heated at a distance from the object of consumption, then the pipelines of the DHW routes must be made according to the circulation scheme. The presence of a dead-end DHW circuit actually means that about 35-45% of the heat energy going to DHW needs, is wasted.

Usually, the loss of thermal energy in heating mains should not exceed 5-7%. But in fact, they can reach values of 25% or more!

3. Losses at the objects of heat consumers. Heating and hot water systems of existing buildings.

The most significant components of heat losses in heat and power systems are losses at consumer facilities. The presence of such is not transparent and can only be determined after the appearance of a heat metering device in the heat station of the building, the so-called. heat meter. Experience with a huge number of domestic thermal systems allows us to indicate the main sources of unproductive losses of thermal energy. In the most common case, these are losses:

in heating systems associated with the uneven distribution of heat over the object of consumption and the irrationality of the internal thermal scheme of the object (5-15%);
in heating systems associated with a discrepancy between the nature of heating and the current weather conditions (15-20%);
in DHW systems due to the lack of hot water recirculation, up to 25% of thermal energy is lost;
in DHW systems due to the absence or inoperability of hot water regulators on DHW boilers (up to 15% of the DHW load);
in tubular (high-speed) boilers due to the presence of internal leaks, contamination of heat exchange surfaces and difficulty in regulation (up to 10-15% of the DHW load).

Total implicit non-productive losses at the consumption site can be up to 35% of the heat load!

The main indirect reason for the presence and increase of the above losses is the absence of heat metering devices at heat consumption facilities. The lack of a transparent picture of heat consumption by the facility causes the resulting misunderstanding of the importance of taking energy-saving measures on it.

3. Thermal insulation

Thermal insulation, thermal insulation, thermal insulation, protection of buildings, thermal industrial installations (or their individual units), cold rooms, pipelines and other from unwanted heat exchange with the environment. So, for example, in construction and thermal power engineering, thermal insulation is necessary to reduce heat losses to the environment, in refrigeration and cryogenic technology - to protect equipment from heat influx from outside. Thermal insulation is provided by the device of special fences made of heat-insulating materials (in the form of shells, coatings, etc.) and hindering heat transfer; these thermal protection means themselves are also called thermal insulation. With a predominant convective heat exchange for thermal insulation, fences containing layers of material that are impervious to air are used; with radiant heat transfer - structures made of materials that reflect thermal radiation (for example, from foil, metallized lavsan film); with thermal conductivity (the main mechanism of heat transfer) - materials with a developed porous structure.

The effectiveness of thermal insulation in the transfer of heat by thermal conduction is determined by the thermal resistance (R) of the insulating structure. For a single-layer structure, R=d/l, where d is the thickness of the layer of insulating material, l is its thermal conductivity. An increase in the efficiency of thermal insulation is achieved by the use of highly porous materials and the installation of multilayer structures with air gaps.

The task of thermal insulation of buildings is to reduce heat losses during the cold season and ensure the relative constancy of the temperature in the premises during the day with fluctuations in the outdoor temperature. By using effective heat-insulating materials for thermal insulation, it is possible to significantly reduce the thickness and weight of building envelopes and thus reduce the consumption of basic building materials (brick, cement, steel, etc.) and increase allowable dimensions prefabricated elements.

Bills for heating and hot water are a significant part of the splits in the core and to a certain extent reflect the level of consumption of thermal energy. In the past, energy was cheap. Now its price has increased and is unlikely to decrease in the foreseeable future. But you can reduce the cost of heating and hot water. This is done with the help of thermomolding. It will reduce heat leakage through the structure of the house and increase the efficiency of heating and hot water systems. Of course, thermal modernization will require considerable financial costs, but if it is done correctly, the costs will be reimbursed from the funds saved on heating.

Where does the heat go?

Consider the main reasons for the high level of consumption of thermal energy in private homes. Heat goes away:

☰ through ventilation. IN modern houses traditional structures thus lose 30-40% of heat;
☰ windows and doors. Usually they account for up to 25% of the total heat loss at home.
☰ In some houses, the size of windows is determined, guided by non-rational norms natural light, but the architectural fashion that came to us from countries with a warmer climate;
☰ external walls. 15-20% of heat escapes through the construction of the walls. The building codes of the past years did not require a high thermal insulation capacity from the wall structure, moreover, they were often violated without that;
☰ roof. Up to 15% of heat escapes through it;
☰ floor on the ground. A common solution in houses without a basement, with insufficient thermal insulation, can lead to a loss of 5-10% of heat;
☰ cold bridges, or thermal bridges. They cause a loss of about 5% of heat.

Insulation of external walls

It consists in creating an additional layer of thermal insulation on the outer or inside outer wall of the house. At the same time, heat losses decrease, and the temperature of the inner surface of the steppe increases, which makes living in the house more comfortable and eliminates the cause of increased humidity and mold. After additional insulation, the thermal insulation properties of the wall are improved by three to four times.

Insulation from the outside is much more convenient and efficient, so it is used in the vast majority of cases. It provides:

☰ uniformity of thermal insulation on the entire surface of the outer wall;
☰ An increase in the thermal static of the wall, that is, the latter becomes a heat accumulator. During the day, it heats up from sunlight, and at night, cooling down, it gives off heat to the room;
☰ elimination of wall unevenness and creation of a new, more aesthetic facade of the house;
☰ performance of work without inconvenience to residents.

Insulation of the house from the inside is used only in exceptional cases, for example, in houses with richly decorated facades or when only some rooms are insulated.

Insulation of ceilings and roofs

Ceilings in an unheated attic are insulated by laying a layer of slabs, mats or bulk materials. If the attic is planned to be used, then a layer of boards or a cement screed is laid over the insulation. Laying an extra layer of thermal insulation in the attic, where it is easy to get to, is actually simple and inexpensive.

More complicated is the situation with the so-called ventilated combined roof, where there is a space of several tens of centimeters above the ceiling of the last floor, to which there is no direct access. Then a special insulation is blown into this space so that, after hardening, it forms a thick heat-insulating layer on the ceiling.

It is possible to insulate a combined roof (this is usually arranged above the attic floors) by laying an additional layer of thermal insulation on it and performing a new roofing. Ceilings above basements are most easily insulated by gluing or hanging insulation with anchors and steel mesh. The thermal insulation layer can be left open or covered with aluminum foil, wallpaper, plaster, etc.

Reducing heat loss through windows

There are several ways to reduce heat loss through the window "carpentry".

Here are the SIMPLE ones:
☰ shrink windows;
☰ note shutters and blinds;
☰ change windows.

by the most in a radical way reducing heat loss is the latter. Instead of old ones, windows with higher thermal insulation properties are installed. The market offers various types of energy-saving trenches: wooden, plastic, aluminum, with two- and three-chamber double-glazed windows, with special low-emission glass. Changing windows will not be cheap, but new ones are easier to care for (plastic windows do not need to be painted), their high density prevents dust from penetrating, sound and heat insulation improves.

Some homes have too many windows, far more than needed for natural light. Therefore, it is possible to reduce their area by filling part of the openings with wall material.

Most low temperatures outside the house, they usually leave at night, when there is no daylight. Therefore, heat loss can be reduced by using shutters or blinds.

Heating and hot water supply system

If the heat supply of the house is carried out with the help of a boiler house, which has been used for 10-15 years, then it requires thermal modernization. The biggest disadvantage of old boilers is their low productivity. In addition, such coal-fired appliances emit a lot of combustion products. Therefore, it is advisable to replace them with modern gas or liquid fuel boilers: they have more productivity and they pollute the air less.

You can upgrade the heating system itself in the house. Alya, they arrange thermal insulation on heating and hot water pipes that pass through unheated rooms. In addition, thermostatic valves are installed on all radiators. This allows you to set the required temperature and not heat non-residential premises. You can also arrange air heating or "warm floor". Modernization of the hot water network is the replacement of leaking pipelines and the thermal insulation of new ones, the optimization of the operation of the hot water system and the inclusion of a circulation pump in it.

Ventilation system

To reduce heat loss through this system, you can install a heat exchanger - a device that allows you to use the heat of the air leaving the house. In addition, heating can be applied supply air. The simplest devices that reduce heat loss through dense modern windows are ventilation pockets that supply air to the premises.

Unconventional Energy Sources

Alya home heating can use renewable energy. For example, heat from burning firewood, waste wood (sawdust) and straw. Alya this use special boilers. The cost of heating in this way is significantly lower than systems operating on traditional fuels.

To use solar heat for heating, use solar collectors located on the roof or on the wall of the house. For maximum efficiency of their work, the collectors should be placed on the southern slope of the roof with a slope of about 45 °. In our climatic conditions, the collectors are usually combined with another heat source, such as a convection gas boiler or a solid fuel boiler.

For heating and hot water supply, heat pumps can be used that use the heat of the earth or groundwater. However, they require electricity to operate. The cost of heat produced by heat pumps is low, but the cost of the pump and the heating system is quite high. The annual heat demand for individual houses is 120-160 kWh/m2. It is easy to calculate that heating a dwelling with an area of 200 m2 will require 24,000-32,000 kWh during the year. By applying a number of technical measures, this value can be reduced by almost two times.

Ministry of Education of the Republic of Belarus

educational institution

"Belarusian National Technical University"

ESSAY

Discipline "Energy Efficiency"

on the topic: “Heat networks. Losses of thermal energy during transmission. Thermal insulation.»

Completed by: Schreider Yu. A.

Group 306325

Minsk, 2006

1. Heating network. 3

2. Losses of thermal energy during transmission. 6

2.1. Sources of losses. 7

3. Thermal insulation. 12

3.1. Thermal insulation materials. 13

4. List of used literature. 17

1. Thermal networks.

A heat network is a system of firmly and tightly interconnected participants in heat pipelines through which heat is transported from sources to heat consumers using heat carriers (steam or hot water).

The main elements of heat networks are a pipeline consisting of steel pipes, interconnected by welding, an insulating structure designed to protect the pipeline from external corrosion and heat loss, and Basic structure, perceiving the weight of the pipeline and the forces arising during its operation.

The most critical elements are pipes, which must be sufficiently strong and tight at maximum pressures and temperatures of the coolant, have a low coefficient of thermal deformation, low roughness of the inner surface, high thermal resistance of the walls, which contributes to the preservation of heat, and the invariance of material properties during prolonged exposure to high temperatures and pressures .

The supply of heat to consumers (heating, ventilation, hot water supply systems and technological processes) consists of three interrelated processes: communication of heat to the heat carrier, transport of the heat carrier and use of the thermal potential of the heat carrier. Heat supply systems are classified according to the following main features: power, type of heat source and type of coolant.

In terms of power, heat supply systems are characterized by the range of heat transfer and the number of consumers. They can be local or centralized. Local heating systems are systems in which the three main links are combined and located in the same or adjacent premises. At the same time, the receipt of heat and its transfer to the air of the premises are combined in one device and are located in heated premises (furnaces). Centralized systems in which heat is supplied from one heat source to many rooms.

By type of heat source of the system district heating divided into district heating and district heating. In the system of district heating, the source of heat is the district boiler house, district heating-CHP.

According to the type of heat carrier, heat supply systems are divided into two groups: water and steam.

Heat carrier is a medium that transfers heat from a heat source to heating devices of heating, ventilation and hot water supply systems.

The heat carrier receives heat in the district boiler house (or CHPP) and through external pipelines, which are called heat networks, enters the heating, ventilation systems of industrial, public and residential buildings. In heating devices located inside buildings, the coolant gives off part of the heat accumulated in it and is discharged through special pipelines back to the heat source.

In water heating systems, the heat carrier is water, and in steam systems, steam. In Belarus, water heating systems are used for cities and residential areas. Steam is used at industrial sites for technological purposes.

Systems of water heat pipelines can be single-pipe and two-pipe (in some cases, multi-pipe). The most common is a two-pipe heat supply system (hot water is supplied to the consumer through one pipe, and chilled water is returned to the CHP or boiler room through the other, return pipe). Distinguish between open and closed heating systems. IN open system“direct water withdrawal” is carried out, i.e. hot water from the supply network is disassembled by consumers for household, sanitary and hygienic needs. With full use of hot water can be applied single pipe system. For closed system characteristic is the almost complete return of network water to the CHPP (or district boiler house).

The following requirements are imposed on the heat carriers of district heating systems: sanitary and hygienic (the heat carrier should not worsen sanitary conditions in enclosed spaces - the average surface temperature of heating devices cannot exceed 70-80), technical and economic (so that the cost of transport pipelines is the lowest, the mass of heating devices - low and ensured the minimum fuel consumption for space heating) and operational (possibility of central adjustment of the heat transfer of consumption systems due to variable outdoor temperatures).

The direction of the heat pipelines is selected according to the heat map of the area, taking into account geodetic survey materials, the plan of existing and planned above-ground and underground structures, data on the characteristics of soils, etc. The question of choosing the type of heat pipeline (above-ground or underground) is decided taking into account local conditions and technical and economic justifications.

With a high level of ground and external waters, the density of existing underground structures on the route of the designed heat pipeline, which is heavily crossed by ravines and railways, in most cases, preference is given to above-ground heat pipelines. They are also most often used on the territory of industrial enterprises in the joint laying of energy and technological pipelines on common overpasses or high supports.

In residential areas, for architectural reasons, underground laying of heating networks is usually used. It is worth saying that above-ground heat-conducting networks are durable and maintainable, compared with underground ones. Therefore, it is desirable to find at least a partial use of underground heat pipelines.

When choosing a heat pipeline route, one should be guided primarily by the conditions of reliability of heat supply, the safety of the work of maintenance personnel and the public, and the possibility of quick elimination of malfunctions and accidents.

For the purposes of safety and reliability of heat supply, networks are not laid in common channels with oxygen pipelines, gas pipelines, compressed air pipelines with a pressure above 1.6 MPa. When designing underground heat pipelines in terms of reducing initial costs, the minimum number of chambers should be chosen, constructing them only at the points of installation of fittings and devices that need maintenance. The number of required chambers is reduced when using bellows or lens expansion joints, as well as axial expansion joints with a large stroke (double expansion joints), natural compensation of temperature deformations.

On a non-carriageway, ceilings of chambers and ventilation shafts protruding to the surface of the earth to a height of 0.4 m are allowed. To facilitate the emptying (drainage) of heat pipelines, they are laid with a slope to the horizon. To protect the steam pipeline from ingress of condensate from the condensate pipeline during the shutdown of the steam pipeline or a drop in steam pressure, check valves or gates should be installed after the steam traps.

A longitudinal profile is built along the heating network route, on which the planning and existing ground marks, the standing groundwater level, existing and planned underground utilities, and other structures intersected by the heat pipeline are applied, indicating the vertical marks of these structures.

2. Losses of thermal energy during transmission.

To assess the efficiency of any system, including heat and power, a generalized physical indicator is usually used - the efficiency factor (COP). physical meaning Efficiency - the ratio of the value obtained useful work(energy) to spent. The latter, in turn, is the sum of the useful work (energy) received and the losses that occur in system processes. Thus, increasing the efficiency of the system (and hence increasing its efficiency) can be achieved only by reducing the amount of unproductive losses that occur during operation. This is the main task of energy saving.

The main problem that arises in solving this problem is to identify the largest components of these losses and select the optimal technological solution that can significantly reduce their impact on the efficiency. Moreover, each specific object (the goal of energy saving) has a number of characteristic design features and the components of its heat loss are different in magnitude. And whenever it comes to improving the efficiency of heat and power equipment (for example, a heating system), before making a decision in favor of using any technological innovation, it is imperative to conduct a detailed examination of the system itself and identify the most significant channels of energy loss. A reasonable decision would be to use only such technologies that will significantly reduce the largest non-productive components of energy losses in the system and at minimal cost significantly increase its efficiency.

2.1 Sources of losses.

Any heat and power system for the purpose of analysis can be divided into three main sections:

1. site for the production of thermal energy (boiler room);

2. section for the transportation of thermal energy to the consumer (pipelines of heating networks);

3. heat consumption area (heated object).

Each of the above sections has characteristic unproductive losses, the reduction of which is the main function of energy saving. Let's consider each section separately.

1.Plot for the production of thermal energy. existing boiler house.

If the regime adjustment of the boiler unit with an inventory of harmful emissions is not carried out in a timely and high-quality manner, losses with underburning of gas can increase by 6-8%;
The diameter of the burner nozzles installed on a medium-sized boiler is usually not recalculated for the actual load of the boiler. However, the load connected to the boiler is different from that for which the burner is designed. This discrepancy always leads to a decrease in heat transfer from torches to heating surfaces and an increase in losses by 2-5% due to chemical underburning of fuel and exhaust gases;
If the surfaces of boiler units are cleaned, as a rule, once every 2-3 years, this reduces the efficiency of the boiler with contaminated surfaces by 4-5% due to an increase in losses with flue gases by this amount. In addition, the insufficient efficiency of the chemical water treatment system (CWT) leads to the appearance of chemical deposits (scale) on the internal surfaces of the boiler, which significantly reduces the efficiency of its operation.
If the boiler is not equipped with a complete set of control and regulation means (steam meters, heat meters, combustion process and heat load control systems) or if the boiler unit control means are not set optimally, then this, on average, further reduces its efficiency by 5%.
If the integrity of the boiler lining is violated, additional suction of air into the furnace occurs, which increases losses with underburning and exhaust gases by 2-5%
The use of modern pumping equipment in the boiler house allows two to three times to reduce the cost of electricity for the boiler house's own needs and reduce the cost of their repair and maintenance.
A significant amount of fuel is spent on each "start-stop" cycle of the boiler. The ideal option for operating a boiler house is its continuous operation in the power range determined by the regime map. The use of reliable shut-off valves, high-quality automation and control devices allows minimizing losses arising from power fluctuations and emergency situations in the boiler room.

Thus, permanent implicit additional losses only during the production of heat in the boiler room can reach a value of 20-25%!

2. Loss of heat in the area of its transportation to the consumer. Existing heating pipelines.

Efficiency of network pumps that ensure the movement of the coolant along the heating main;
losses of thermal energy along the length of heating mains associated with the method of laying and insulating pipelines;
losses of thermal energy associated with the correct distribution of heat between consumer objects, the so-called. hydraulic configuration of the heating main;
coolant leaks that occur periodically during emergency and emergency situations.

the use of domestic powerful network pumps with low efficiency almost always leads to significant unproductive energy overruns.
with a large length of pipelines of heating mains, the quality of thermal insulation of heating mains acquires a significant impact on the magnitude of heat losses.
hydraulic adjustment of the heating main is a fundamental factor determining the efficiency of its operation. The objects of heat consumption connected to the heating main must be properly spaced so that the heat is distributed evenly over them. Otherwise, thermal energy ceases to be effectively used at consumption facilities and a situation arises with the return of part of the thermal energy through the return pipeline to the boiler house. In addition to reducing the efficiency of boilers, this causes a deterioration in the quality of heating in the most remote buildings along the heating network.
if water for hot water supply systems (DHW) is heated at a distance from the object of consumption, then the pipelines of the DHW routes must be made according to the circulation scheme. The presence of a dead-end DHW circuit actually means that about 35-45% of the heat energy used for the needs of the DHW is wasted.

Usually, the loss of thermal energy in heating mains should not exceed 5-7%. But in fact, they can reach values of 25% or more!

3. Losses at the objects of heat consumers. Heating and hot water systems of existing buildings.

in heating systems associated with the uneven distribution of heat over the object of consumption and the irrationality of the internal thermal scheme of the object (5-15%);
in heating systems associated with a discrepancy between the nature of heating and current weather conditions (15-20%);
in DHW systems, due to the lack of hot water recirculation, up to 25% of thermal energy is lost;
in DHW systems due to the absence or inoperability of hot water regulators on DHW boilers (up to 15% of the DHW load);
in tubular (high-speed) boilers due to the presence of internal leaks, contamination of heat exchange surfaces and difficulty in regulation (up to 10-15% of the DHW load).

Total implicit non-productive losses at the consumption site can be up to 35% of the heat load!

3. Thermal insulation

Thermal insulation, thermal insulation, thermal insulation, protection of buildings, thermal industrial installations (or their individual units), refrigerators, pipelines and other things from unwanted heat exchange with the environment. So, for example, in construction and thermal power engineering, thermal insulation is necessary to reduce heat losses to the environment, in refrigeration and cryogenic technology - to protect equipment from heat influx from outside. Thermal insulation is provided by the device of special fences made of heat-insulating materials (in the form of shells, coatings, etc.) and hindering heat transfer; these thermal protection means themselves are also called thermal insulation. With a predominant convective heat exchange for thermal insulation, fences containing layers of material that are impervious to air are used; with radiant heat transfer - structures made of materials that reflect thermal radiation (for example, from foil, metallized lavsan film); with thermal conductivity (the main mechanism of heat transfer) - materials with a developed porous structure.

The task of thermal insulation of buildings is to reduce heat losses during the cold season and ensure the relative constancy of the temperature in the premises during the day with fluctuations in the outdoor temperature. By using effective thermal insulation materials for thermal insulation, it is possible to significantly reduce the thickness and weight of building envelopes and thus reduce the consumption of basic building materials (brick, cement, steel, etc.) and increase the allowable dimensions of prefabricated elements.

In thermal industrial installations (industrial furnaces, boilers, autoclaves, etc.), thermal insulation provides significant fuel savings, increases the power of thermal units and increases their efficiency, intensifies technological processes, and reduces the consumption of basic materials. The economic efficiency of thermal insulation in industry is often evaluated by the heat saving coefficient h = (Q 1 - Q 2) / Q 1 (where Q 1 is the heat loss of the installation without thermal insulation, and Q 2 - with thermal insulation). Thermal insulation of industrial installations operating at high temperatures also contributes to the creation of normal sanitary and hygienic working conditions for maintenance personnel in hot shops and the prevention of industrial injuries.

3.1 Thermal insulation materials

The main areas of application of heat-insulating materials are the insulation of building envelopes, process equipment (industrial furnaces, thermal units, refrigerators, etc.) and pipelines.

Not only heat losses, but also its durability depend on the quality of the insulating structure of the heat pipe. With the appropriate quality of materials and manufacturing technology, thermal insulation can simultaneously play the role of anti-corrosion protection of the outer surface of the steel pipeline. Such materials include polyurethane and derivatives based on it - polymer concrete and bion.

The main requirements for thermal insulation structures are as follows:

low thermal conductivity both in the dry state and in the state natural humidity;

· small water absorption and small height of capillary rise of liquid moisture;

low corrosive activity;

High electrical resistance

alkaline reaction of the medium (pH> 8.5);

Sufficient mechanical strength.

The main requirements for heat-insulating materials for steam pipelines of power plants and boiler houses are low thermal conductivity and high thermal stability. Such materials are usually characterized by a high content of air pores and a low bulk density. The latter quality of these materials predetermines their increased hygroscopicity and water absorption.

One of the main requirements for thermal insulation materials for underground heat pipelines is low water absorption. Therefore, high-performance heat-insulating materials with a high content of air pores, which easily absorb moisture from the surrounding soil, are generally unsuitable for underground heat pipelines.

There are rigid (slabs, blocks, bricks, shells, segments, etc.), flexible (mats, mattresses, bundles, cords, etc.), loose (granular, powdery) or fibrous heat-insulating materials. According to the type of the main raw materials, they are divided into organic, inorganic and mixed.

Organic, in turn, are divided into organic natural and organic artificial. Organic natural materials include materials obtained by processing non-commercial wood and woodworking waste ( fibreboard and particle boards), agricultural waste (straw, reeds, etc.), peat (peat slabs), and other local organic raw materials. These thermal insulation materials, as a rule, are characterized by low water and bioresistance. These shortcomings are deprived of organic artificial materials. Very promising materials of this subgroup are foams obtained by foaming synthetic resins. Foam plastics have small closed pores and this is different from foam plastics - also foamed plastics, but with connecting pores and therefore not used as heat-insulating materials. Depending on the recipe and the nature of the manufacturing process, foams can be rigid, semi-rigid and elastic with pores of the required size; desired properties can be imparted to products (for example, combustibility is reduced). A characteristic feature of most organic heat-insulating materials is low fire resistance, so they are usually used at temperatures not exceeding 150 °C.

More fire-resistant materials of mixed composition (fibrolite, wood concrete, etc.) obtained from a mixture of mineral binder and organic filler (wood chips, sawdust, etc.).

inorganic materials. A representative of this subgroup is aluminum foil (alfol). It is used in the form of corrugated sheets laid with the formation of air gaps. The advantage of this material is its high reflectivity, which reduces radiant heat transfer, which is especially noticeable at high temperatures. Other representatives of the subgroup of inorganic materials are artificial fibers: mineral, slag and glass wool. The average thickness of mineral wool is 6-7 microns, the average thermal conductivity coefficient is λ=0.045 W/(m*K). These materials are not combustible, not passable for rodents. They have low hygroscopicity (no more than 2%), but high water absorption (up to 600%).

Lungs and cellular concrete(mainly aerated concrete and foam concrete), foam glass, glass fiber, expanded perlite products, etc.

Inorganic materials used as mounting materials are made on the basis of asbestos (asbestos cardboard, paper, felt), mixtures of asbestos and mineral binders (asbestos-diatom, asbestos-lime-silica, asbestos-cement products) and on the basis of expanded rocks(vermiculite, perlite).

For insulation industrial equipment and installations operating at temperatures above 1000 ° C (for example, metallurgical, heating and other furnaces, furnaces, boilers, etc.), so-called lightweight refractories are used, made from refractory clays or highly refractory oxides in the form of piece products (bricks , blocks of various profiles). It is also promising to use fibrous thermal insulation materials made of refractory fibers and mineral binders (their thermal conductivity coefficient at high temperatures is 1.5-2 times lower than that of traditional ones).

Thus, there are a large number of thermal insulation materials from which a choice can be made depending on the parameters and operating conditions of various installations that need thermal protection.

4. List of used literature.

1. Andryushenko A.I., Aminov R.Z., Khlebalin Yu.M. "Heating plants and their use". M. : Vyssh. school, 1983.

2. Isachenko V.P., Osipova V.A., Sukomel A.S. "Heat transfer". M.: energy publishing house, 1981.

3. R.P. Grushman "What a heat insulator needs to know." Leningrad; Stroyizdat, 1987.

4. Sokolov V. Ya. "Heat supply and heat networks" Publishing house M .: Energy, 1982.

5. Thermal equipment and heating networks. G.A. Arseniev and others. M.: Energoatomizdat, 1988.

6. "Heat transfer" V.P. Isachenko, V.A. Osipova, A.S. Sukomel. Moscow; Energoizdat, 1981.

Progressive technologies make it possible to increase the durability of heating networks, increase their reliability and at the same time increase the efficiency of heat transport.

The following is a brief description of such technologies.

1) Channelless laying of heat pipelines of the "pipe in pipe" type with polyurethane foam insulation in a polyethylene sheath and an insulation moisture control system.

Such heat pipelines make it possible to eliminate by 80% the possibility of damage to pipelines from external corrosion, reduce heat losses through insulation by 2-3 times, reduce operating costs for maintaining heating mains, reduce construction time by 2-3 times, reduce capital costs by 1.2 times with laying of heating mains in comparison with channel laying. Polyurethane foam insulation is designed for long-term exposure to coolant temperatures up to 130°C and short-term peak exposure to temperatures up to 150°C. Necessary condition reliable and trouble-free operation of pipelines of heating networks - the presence of a system of operational-remote control (ODC) of insulation. This system allows you to control the quality of installation and welding of steel pipelines, factory insulation, insulation of butt joints. The system includes: alarm copper conductors embedded in all elements of the heating system; terminals along the route and in places of control (CTP, boiler room); control devices: portable for periodic and stationary for continuous control. The system is based on measuring the conductivity of the thermal insulation layer, which changes with changes in humidity. Control over the state of the UEC during the operation of the pipeline is carried out using a detector. One detector allows you to simultaneously control two pipes up to 5 km each. Exact location damaged area determined using a portable locator. One locator allows you to determine the location of damage at a distance of up to 2 km from the point of its connection. The service life of heat networks with polyurethane foam insulation is predicted to be 30 years.

2) Bellows compensators, unlike stuffing boxes, provide complete tightness of compensating devices, reduce operating costs. Reliable bellows expansion joints are produced by Metalcomp JSC for all pipeline diameters with channelless, channel, ground and aboveground laying. The use of bellows expansion joints in Mosenergo JSC installed on main pipelines with a diameter of 300 to 1400 mm in the amount of more than 2000 pieces, made it possible to reduce specific water leakage from 3.52 l/m 3 h in 1994 to 2.43 l/m 3 h in 1999.
3) High-density ball valves, hydraulically actuated ball valves used as shear valves, can improve performance characteristics fittings and fundamentally change the existing schemes for protecting heating systems from pressure increase.
4) The introduction of new schemes for regulating the performance of pumping stations using variable frequency drives, the use of protection schemes against pressure increase in the return line when the pumping station is stopped can significantly improve the reliability of equipment operation and reduce power consumption during the operation of these stations.
5) Ventilation of channels and chambers is aimed at reducing heat losses through the insulation of heat pipelines, which is one of the most important tasks in the operation of heat networks. One of the reasons for the increased heat loss through the insulation of the heat pipe of the underground laying is its moistening. To reduce humidity and reduce heat losses, it is necessary to ventilate channels, chambers, which allows maintaining the moisture state of thermal insulation at a level that ensures minimal heat losses.
6) About a third of damage to heating networks is due to internal corrosion processes. Even compliance with the normative value of leaks of heat networks, equal to 0.25% of the volume of all pipelines, which is 30,000 t/h, leads to the need for strict control of the quality of make-up water.

The main parameter that can be influenced is the pH value.

Increasing the pH value of network water is a reliable way to combat internal corrosion, provided that the normalized oxygen content is maintained in the water. The high degree of protection of pipelines at pH 9.25 is determined by the change in the properties of iron oxide films.

The level of pH increase that provides reliable protection pipelines from internal corrosion, significantly depends on the content of sulfates and chlorides in the network water.

The higher the concentration of sulfates and chlorides in the water, the higher the pH value should be.

One of the few ways to extend the working life of heat networks laid in the standard way, excluding pipelines in polyurethane foam insulation, are anti-corrosion coatings.

Thermal insulation of pipelines and heating network equipment is used for all types of laying, regardless of the temperature of the coolant. Thermal insulation materials are in direct contact with the external environment, which is characterized by continuous fluctuations in temperature, humidity and pressure. In view of this, heat-insulating materials and structures must satisfy a number of requirements. Considerations of economy and durability require that the choice of heat-insulating materials and construction be made taking into account the laying methods and operating conditions determined by the external load on the heat-insulation, the level of groundwater, the temperature of the heat carrier, and the hydraulic mode of operation of the heating network.

New types of heat-insulating coatings should have not only low thermal conductivity, but also low air and water permeability, as well as low electrical conductivity, which reduces electrochemical corrosion of the pipe material.

The most economical type of laying of heat pipelines of heating networks is above-ground laying. However, taking into account architectural and planning requirements, environmental requirements in settlements, the main type of laying is underground laying in through, semi-through and non-through channels. Channelless heat pipelines, being more economical in comparison with channel laying in terms of capital costs for their construction, are used in cases where they thermal efficiency and durability are not inferior to heat pipes in impassable channels.

Thermal insulation is provided for linear sections of pipelines of heating networks, fittings, flange connections, compensators and pipe supports for aboveground, underground channel and channelless laying.

Heat losses from the surface of pipelines increase when the thermal insulation is moistened. Moisture to the surface of pipelines comes when they are flooded with ground and surface waters. Other sources of dampening of thermal insulation is the natural moisture contained in the soil. If the pipelines are laid in the channels, then on the surface of the ceilings of the channels, moisture condensation from the air is possible and it can enter in the form of drops on the surface of the pipelines. To reduce the impact of drops on thermal insulation, it is necessary to ventilate the channels of heating networks. Moreover, the moistening of thermal insulation contributes to the destruction of pipes due to their corrosion. outer surface, which leads to a reduction in the service life of pipelines. Therefore, on metal surface pipes are coated with anti-corrosion coatings.

Thus, the main energy-saving measures that reduce heat loss from the surface of pipelines are:

§ Insulation of uninsulated areas and restoration of the integrity of existing thermal insulation;
§ restoration of the integrity of the existing waterproofing;
§ applying coatings consisting of new heat-insulating materials, or using pipelines with new types of heat-insulating coatings;
§ insulation of flanges and valves.

Insulation of uninsulated sections is a primary energy saving measure, since heat losses from the surface of uninsulated pipelines are very large compared to losses from the surface of insulated pipelines, and the cost of applying thermal insulation is relatively low.

Let's compare heat losses by non-insulated heat pipelines with a heat network with pre-insulated pipes using the heat supply system of the city of Shatura as an example.

Heat supply specifics
The importance of solving heat supply problems is determined by several factors.

Fuel costs for heat supply are enormous. Only for pumping network water in district heating systems, about 50 billion kW are needed. h of electricity per year; and taking into account the consumption of electricity at thermal points and for direct electric heating, the consumption of natural gas and liquid hydrocarbons for local heating of dwellings, the cost of fossil fuel for heat supply is more than 40% of all used in the country, i.e. almost as much as is spent on all other branches of industry, transport, etc. taken together. Fuel consumption by heat supply is comparable to all fuel exports of the country.
The largest reserves of energy savings are also concentrated in the process of providing heat. Electric energy savings can be achieved mainly by improving power installations (electricity sources, transport, energy-using installations at the consumer), and thermal energy savings can be achieved not only by improving heat sources, heating networks, heat-consuming installations, but also by improving the characteristics of heated objects (enclosing structures of buildings and structures, ventilation, window construction, etc.).
In the electric power industry, with the adoption of a package of laws on reform, conditions have appeared for the development of competition (dependence of the price in the electricity market over time, competition of sources, etc.), which creates financial incentives for market participants to improve their energy processes to reduce costs. And the federal law “On Heat Supply” has not yet been adopted, and even with its introduction, the possibilities for creating a competition system will be severely limited. Accordingly, where there are no market relations, it is difficult to create a system of incentives for energy conservation.
There is a close relationship between heat supply and fuel and gas supply systems, as well as electricity supply. Electrical energy is a substitute energy for district heating (DH) systems. Violations in DH systems are critical for power supply systems, during severe cold snaps, the need for heat is much greater than for electricity, and in case of violation of heat supply modes Electric Energy used in the most irrational way - for space heating. Also, the heat load of DH systems is the basis for district heating, i.e. use of heat waste from the process of electricity production for heat supply purposes.
With regard to district heating systems, not everyone understands the huge benefits of DH in terms of energy savings, they need to be explained. Aggressive advertising of individual heat sources proposed for implementation in the district heating system coverage area with reference to foreign experience misleads consumers. In the West, programs are being adopted to support the development of district heating systems as the basis for cogeneration. In contrast to our country, where DH has historically developed predominantly, the main problem there is the difficulty of laying heating networks in cramped urban conditions and the reorientation of consumers from autonomous to centralized heat supply.

Actual loads and losses
According to the results of energy surveys, the calculated and contractual connected heat loads differ significantly from the actual ones, usually in the direction of excess. Overestimation of loads, with insufficient equipment of consumers with metering devices and calculations for metering devices at sources, makes it possible for heat supply organizations to underestimate excess losses in networks and, accordingly, overestimate the volume of sold thermal energy.
Estimated loads are the main input data for the development of normative energy characteristics. If they differ from the actual ones, the calculated regime characteristics are obtained, which are unattainable in reality. The lack of reliable standards does not allow for a full-fledged analysis of the energy efficiency of networks.
The actual loads are also important for determining the reserves of the heat supply system.
Heat supply from sources = Consumption + Actual losses in networks
To balance, you need to know at least two components. In the absence of 100% equipment with metering devices, in most cases it is easier to determine the supply of heat from sources and the actual losses in the networks. Vacation, subject to verification of reliability, can be determined by heat energy meters at heat sources or the fuel balance of the source in the presence of fuel metering. The actual losses in the networks are determined according to the methods allowed for use in the energy audit procedure, i.e. archives of metering devices available to consumers are used (at least 20% of consumers). When applying these methods, there is no need to carry out additional measurements and tests.
The determination of the actual loads and losses should be integral part development of the general fuel and energy balance of the municipality.
The actual losses of network water, according to the results of energy surveys, are usually commensurate with the normative leakage, equal to 0.25% of the volume of heat networks per hour. In a number of regions they do not exceed the standard. So, in Moscow, the actual losses of network water and, accordingly, the losses of thermal energy with them are 2-3 times lower than the normative ones. This fact characterizes, first of all, not only the satisfactory state of heating networks, but overestimated norms that do not reflect the capabilities of new technologies. At the federal and regional levels, it is necessary to adjust the norms for losses of network water in the direction of reduction.
Determination of thermal energy losses through thermal insulation in accordance with the "Methodological guidelines for determining thermal losses in water heating networks (RD 34.09.255-97)" is practically not carried out anywhere. Thus, the requirements of the "Rules for the technical operation of power plants and networks of the Russian Federation" are violated. The reason is the complexity and high cost of testing, the need to disconnect consumers.
The results of the energy audit of heat supply systems show that the actual losses in the examined heat networks exceed the normative ones by 1.2-2 times.
Bringing heat losses to standard values, in addition to saving thermal energy and reducing the cost of electricity for its transportation, will ensure the release of thermal power. This may eliminate the need to build new heat sources. Thus, when evaluating economic efficiency relocation of heating network sections should take into account not only the saved heat, but also the capital costs for the construction of new sources.
It is necessary to recognize the fact of the presence of excess heat losses, which is becoming more and more obvious with the trend towards an increase in the proportion of consumers equipped with metering devices.
into practice heat supply organizations it is necessary to introduce an analysis of the state of heat networks not only in terms of the ratio of heat losses to supply, but also in terms of the ratio actual losses to the normative. The first indicator currently used for analysis is incorrect, because it characterizes not only the state of the heating network, but also its configuration and thermal insulation design standards.

Methods for reducing losses in heat networks
The main methods are to reduce energy losses:

periodic diagnostics and monitoring of the state of heating networks;
drainage of channels;
replacement of dilapidated and most frequently damaged sections of heating networks (primarily those subject to flooding) based on the results of engineering diagnostics, using modern heat-insulating structures;
drain cleaning;
restoration (application) of anti-corrosion, heat and waterproofing coatings in accessible places;
ensuring high-quality water treatment of make-up water;
organization of electrochemical protection of pipelines;
restoration of waterproofing of joints of floor slabs;
ventilation of channels and chambers;
installation of bellows expansion joints;
use of improved pipe steels and non-metallic pipelines;
organization of real-time determination of actual losses of thermal energy in main heat networks according to data from thermal energy meters at a thermal power plant and at consumers in order to promptly make decisions to eliminate the causes of increased losses;
strengthening supervision during emergency recovery work by administrative and technical inspections;
transfer of consumers from heat supply from central to individual heat points.

Incentives and criteria for personnel should be created. Today's task of the emergency service: come, dig, patch, fall asleep, leave. The introduction of only one criterion for evaluating activity - the absence of repeated openings, immediately radically changes the situation (breaks occur in places of the most dangerous combination of corrosion factors and increased requirements must be imposed on the replaced local sections of the heating system in terms of corrosion protection). Diagnostic equipment will immediately appear, there will be an understanding that if this heating main is flooded, it must be drained, and if the pipe is rotten, then the emergency service will be the first to prove that the network section needs to be changed.
It is possible to create a system in which the heating network, on which a rupture has occurred, will be considered as if “sick” and will be admitted for treatment to the repair service, as to a hospital. After the “treatment”, it will return to the operational service with a restored resource.
Economic incentives are also very important for operating personnel. 10-20% savings from leakage loss reduction (subject to the norm of network water hardness) paid to personnel works better than any external investment. At the same time, due to the reduction in the number of flooded sections, losses through insulation are reduced and the service life of networks is increased.
Heat losses in heating networks should not exceed 5–7%, as is the case in European countries. However, our thermal networks are significantly inferior to foreign ones. Currently, in most heat networks in the CIS countries, the technological consumption of thermal energy for its transportation reaches 30% of the transmitted thermal energy. This value depends on the state of heating networks and, first of all, on the state of thermal insulation.
It is necessary to radically improve the quality of replacement of heat networks by:

preliminary examination of the relocated area in order to determine the causes of failure normative term service and preparation of high-quality technical specifications for design;
mandatory development of major overhaul projects with justification of the predicted service life;
independent instrumental verification of the quality of laying heating networks;
introduction of personal responsibility of officials for the quality of the gasket.

The technical problem of ensuring the standard service life of heat networks was solved back in the 1950s. due to the use of thick-walled pipes and the high quality of construction work, primarily anti-corrosion protection. Now set technical means much wider.
Previously, the technical policy was determined by the priority of reducing capital investments. With lower costs, it was required to ensure the maximum increase in production, so that this increase would offset the costs of repairs in the future. In today's situation, this approach is not acceptable. Under normal economic conditions, the owner cannot afford to lay networks with a service life of 10-12 years; this is ruinous for him. This is all the more unacceptable when the population of the city becomes the main payer. In each municipality, strict control over the quality of laying heat networks should be exercised.
Spending priorities must be changed, most of which is spent today on replacing sections of heating networks where there were pipe breaks during operation or summer pressure testing, on preventing the formation of breaks by monitoring the rate of pipe corrosion and taking measures to reduce it.
An obvious way to reduce the loss of thermal energy during its transmission through heat networks is to replace the traditional for Russia laying of pipelines in mineral wool as thermal insulation with a gasket in polyurethane foam or in another thermal insulation that is no less effective.
Replacement of stuffing box expansion joints with bellows, obsolete shut-off valves with new ball valves, etc., provides a sharp reduction in coolant losses due to its leakage, and hence the loss of thermal energy.
However, there is a less obvious, but cheaper way to reduce energy costs in heat supply systems - optimizing the hydraulic modes of operation of heat networks. The elimination of the misalignment of heat networks reduces the loss of thermal energy and the cost of electricity for the transfer of the coolant in the heat supply system, in some cases up to 40-50%. This is explained by the fact that in order to “heat” consumers located farthest from the heat supply source, the nearest consumers have to be overheated, increasing the flow rate of the coolant. In addition, in order to carry out at least some kind of circulation in the heating systems of these remote buildings, they often resort to "drain" work. That is why the elimination of misalignment of heat networks and the normalization of heat supply bring a significant economic effect.
All costs for new pipes, polyurethane foam insulation, bellows expansion joints and ball valves become useless without regulation of heating networks, that is, without carrying out special works on optimization of hydraulic regimes. The fact is that water heating installations of heat supply sources, their heat networks and heat consumption systems, especially when they are connected to heat networks by dependent schema, represent a single complex hydraulic system, united by a common mode of operation.
The organization of hydraulic operating modes of the heating network, in which the required distribution of the coolant flow between all consumers would be ensured, is one of the most important, but difficult tasks. It needs to be solved in order to efficient work heat supply systems as a whole and each heat consumption system separately. This requires the joint efforts of all organizations operating the heat supply system, since we have to deal, as was said, with a single hydraulic system– a water heating network with numerous heat consumption systems through which the coolant circulates – network water.
Due to the high density of the heat carrier, water heating networks are characterized by low hydraulic stability. As a result, they are subject to misalignment in case of any disturbances - connecting or disconnecting consumers, changing the switching of the heating network, changing the coolant flow in individual heat consumption systems, for example, during the operation of hot water regulators, etc.
District heating systems have been in continuous change since their inception. The length of pipelines is growing or, on the contrary, is reduced due to the disconnection of some consumers. This periodically creates difficulties in organizing the hydraulic regimes of heating networks and managing them.
A lot of heat "leaves" through the walls, floors, ceilings, windows and doors of old buildings and structures. In old brick buildings, losses are approximately 30%, and in buildings made of concrete slabs with built-in radiators - up to 40%. Heat losses in buildings also increase due to the uneven distribution of heat in rooms, so it is advisable to equalize the temperature difference (floor - ceiling) using ceiling fans. Due to this, heat loss can be reduced by up to 30%. To reduce heat leakage from the premises, it is desirable to do air curtain.
Heat losses also increase with excessive heating. The way out of the situation is to install shields outside the buildings from thermal insulation material(thermal coats), as well as replacement window frames double-glazed windows. Since double-glazed windows have several air gaps, their installation allows you to reduce heat loss through windows by half. These activities are called thermal rehabilitation. They allow to reduce heat losses in old buildings up to 10-15%. When constructing new buildings, thermal rehabilitation is already provided.
Heat regulation also helps to reduce the loss of thermal energy in the premises, taking into account the orientation of the house in parts of the world, which we have not done yet.
The main condition for the normal functioning of heat supply systems is the provision in heat networks, in front of the heat points of consumers, of a disposable pressure sufficient for the occurrence of a coolant flow in heat consumption systems corresponding to their heat needs. However, due to the low hydraulic stability of heating networks, under various disturbances, misalignment occurs in them - the greater, the lower their hydraulic stability.
There is an opportunity to significantly increase the hydraulic stability of heat networks and heat supply systems.
An analysis of the functioning of many heat networks has shown that their hydraulic stability is the higher, the lower the pressure loss in the pipelines of heat networks and the greater the head available in front of the heat point of the most distant consumer.
To increase the hydraulic stability of heat networks, it is necessary to throttle the excess part of the available pressure using hydraulic resistances of constant or variable cross-section - throttle diaphragms and elevator nozzles or control valves of means automatic regulation. These resistances must be installed in front of each heating system or in front of individual heat exchangers.
So, the adjustment of water heating networks is based on an all-round increase in their hydraulic stability through the widespread installation of specially designed throttling devices - in front of each of the heat consumption systems, regardless of its heat load. As a result, each of the heat consumption systems in the unified district heating system is placed in the same conditions compared to the others. All heat consumption systems become hydraulically equidistant from the source of heat supply.
The regulation of water heating networks consists in the distribution of the heat carrier flow between all connected heat consumption systems in proportion to their calculated heat load.
The regulation of the heat network is reduced to the regulation of the functioning of individual heat consumption systems by changing, if necessary, the hydraulic resistance of the installed throttling devices.
The criteria for the correct regulation of heat networks are the following indicators:
- establishment of the calculated flow rate of the heat carrier in the heating network and in each of the heat consumption systems;
- compliance with the required temperature difference in each of the heat consumption systems;
- maintaining the calculated air temperature in heated buildings.
The regulation of the heat network must necessarily be preceded by a thorough examination of the heat supply system and the development of optimal operating modes for a particular heat network. Based on this, adjustment (optimization) measures should be developed and implemented in full.
Attempts to regulate the heat network without developing specifically for it the optimal hydraulic regime and optimization measures (and their implementation in full) lead to even greater misalignment of the heat supply system and, consequently, to excessive costs of fuel, electricity and water to feed the heat network.
Accounting for the supply and consumption of thermal energy and heat carriers is carried out in accordance with the rules for accounting for thermal energy and heat carrier, approved by the First Deputy Minister of Fuel and Energy Russian Federation September 12, 1995
However, the degree of equipment of heat consumption systems and some sources of heat supply (mainly heating boiler systems of public heat supply) does not allow making calculations for the received heat energy and heat carriers on the basis of the rules. Rules for the use of electrical and thermal energy, approved by the Order of the Ministry of Energy and Electrification of the USSR No. 310 of December 6, 1981, were canceled in 2000.
Thus, Art. 11 of the Federal Law No. 28-FZ of 04/03/1996 (as amended on 04/05/2003) "On Energy Saving" is not complied with. Accounting for thermal energy and heat carriers, which in itself cannot give an energy-saving effect, but should stimulate energy saving in the process of heat supply, currently does not have a proper regulatory framework.
The functions of developing and approving the rules for accounting for thermal energy are not mentioned either in the regulation on the Ministry of Energy or in the regulation on the Ministry of Regional Development. As a result, the rules for the commercial accounting of thermal energy, reflecting the real situation, have not yet been considered and approved.
Program for improving the reliability of heat networks
To realize the potential of energy saving, it is necessary to introduce a whole range of measures, among which the priority is given to measures aimed at improving the reliability of the functioning of heat networks. The work that is being carried out in thermal organizations on the reconstruction of thermal networks contributes to an increase in the efficiency of transport and distribution systems of thermal energy. But very often the expected effect is not realized due to violations of the requirements of normative and technical documents of NTD, which apply to the operation, construction and overhaul of heating networks.
These operational violations include:

lack of control over the actual state of heat pipelines during operation, no periodic technical examinations thermal networks;
no measures are taken to extend the service life of existing heat pipelines;
operating personnel do not know the methods of corrosion protection, training is not carried out and is not planned;
there is no constant monitoring of the condition of pipelines in PPU - insulation with UEC systems due to the absence or malfunction of control devices;
poor quality of emergency repair work;
there is no control over the actual losses of thermal energy through the thermal insulation of heat pipelines, which characterize the state of heat networks.

Violations during the construction and overhaul of heating networks:

overhaul is carried out without projects and analysis of the causes of premature failure of heat pipelines, which leads to a repetition of previously made mistakes;
projects for the new construction of heating networks do not take into account the actual conditions for laying the route;
project design does not match regulatory documents, projects of low technical quality, errors in calculations for strength and cyclicity, the use of steel grades not provided for by GOST, ill-conceived transmission, etc. are also submitted for approval.
the terms of reference for the design do not contain data on the basis of which the main measures necessary to protect against external corrosion and ensure the estimated service life of heat pipelines, actual operating conditions and reasons that have reduced the estimated service life are developed;
in projects there is no estimated service life of heat networks;
corrosion processes are intensified due to the use of materials and products in the laying of heating networks that do not meet the requirements of the current NTD;
work on the design, installation and commissioning of systems for online remote control of pipelines in polyurethane foam insulation is carried out in violation of the requirements of the current NTD, which leads to a decrease in the service life of heating networks below the calculated one, the quality of laying the pipes themselves in polyurethane foam insulation does not always comply with regulatory documents , low-quality transition nodes from PPU to standard thermal insulation, lack of docking of UEC sections into a single system, construction of high-rise buildings in close proximity to the heating network;
low qualification of the personnel of contractors performing work;
heat pipelines laid in violation of the provisions of the current NTD (quality of anti-corrosion coatings, thickness of thermal insulation, etc.) are accepted for operation.

In view of the foregoing, it is necessary to include the development of a program to improve the reliability of heat networks among the priority measures. It is necessary to formulate in the program all measures to improve the reliability of heat networks, tested on existing heat networks, but not widely used.
The program should include a list of organizational and technical measures taken during operation, current repair, replacement and new construction of heating networks with the rationale for each event.
Among the organizational measures, the following should be noted:

organization of a corrosion protection service in heat supply enterprises, making it responsible for coordinating work to control the corrosion state of heating networks, introducing protective measures, determining the resource, introducing methods of economic incentives, developing technical specifications for corrosion protection, preparing plans for scientific and technical work, staff training;
restore the state acceptance into operation of heating networks with an independent instrumental control of the quality of the laying;
make a gradual transition from destructive methods of monitoring heat networks to non-destructive ones, massively introduce a system of local preventive maintenance with the replacement of specific places of maximum corrosion damage, with the reorientation of emergency services, from eliminating accidents to preventing them;
conduct a mandatory investigation into the causes of premature failure of pipelines of heating networks, identifying the causes, specific perpetrators and measures necessary to prevent such situations, the investigation should be carried out with the participation of representatives of Rostekhnadzor .;
organize mandatory training of operating personnel in corrosion protection methods to the requirements of regulatory documents.

Of course, this list of activities does not claim to be exclusive and is not exhaustive. For there are a great many opportunities on the way to ensuring energy efficiency, and an effective energy saving program is a product of intellectual work, the result of the joint work of an energy auditor and the energy service of an organization that is a consumer of fuel and energy resources.
Adjustment of heat supply systems
To improve the efficiency of existing power supply systems for settlements, an effective system of control over the performance indicators of their work is needed.
Existing quality control heating season actually comes down to accounting for accidents and incidents. But this does not indicate the actual quality of heat supply (sufficiency of the amount of heat consumed and its quality indicators, the efficiency of using the temperature potential of the heat carrier, the minimum costs for transport and distribution of heat).
Existing system payment for the heat received takes into account only its quantity. There is a need, along with quantity, to take into account the quality of the heat received, which provides for an increase in responsibility, both on the part of heat supply organizations and consumers.
More and more importance acquires the adjustment of heat supply systems, designed to ensure a reliable and economical mode of distribution of the heat carrier to consumers in accordance with their heat loads. In all regions of the Russian Federation, there is a hydraulic misalignment of heat supply systems, regardless of the thermal power of thermal energy sources. Lack of adjustment work is the cause of overheating for some consumers and non-heating for others, while there is a significant excess fuel consumption, up to 30%. Considering that the structure of heat networks in small towns of the Russian Federation often develops chaotically, the need for commissioning is especially acute. With rising energy prices, the need for adjustment work only increases.
Regime adjustment of the district heating system consists in ensuring the calculated temperatures inside the heated premises and the specified operating modes of the air heaters, water heating and various kinds of technological installations that consume thermal energy from the heating network with the optimal mode of operation of the system as a whole.
Regime adjustment covers the main links of the district heating system:

water heating plant of CHP or boiler room;
central heating point (CHP);
water heating network with control and distribution points (KRP) installed on it, pumping, throttle substations and other structures;
individual heat points (ITP);
local heating systems.

Control tasks for district heating systems include:

providing a heat source with the specified hydraulic and thermal regimes;
ensuring the estimated flow rate of the coolant for all heat consumption systems connected to the heating network, as well as for heat-consuming devices;
ensuring the calculated internal air temperatures in the room

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