Determination of the structure of unaccounted water consumption using the zoning method

Examination of water supply and sewerage systems - our experience

Water losses in heating networks: methods for reducing the volume of leaks

Water losses in heating networks: methods for reducing leakage volumes

The task of reducing water losses is very urgent today. Coolant leaks and, as a consequence, significant heat losses exist on most existing networks. As a result, the volume of necessary make-up water and the cost of its preparation increase.

Main causes of leaks:

• Destruction of pipes due to corrosion.
• Poor fit of the regulating and shut-off valves.
• Violations of the integrity of the pipeline under the influence of mechanical loads that occur due to poor-quality installation.

To replenish leaks, the energy of a heat source is required (make-up water is heated to a certain temperature), which leads to unnecessary costs.

Hot water losses can be:

• emergency;
• permanent.

Constants in heating networks depend on the area of ​​leaky areas and pressure. Accidental leaks are associated with pipeline ruptures. Losses cold water(cooled coolant) due to accidents are quite rare. The vast majority of accidents occur on supply pipelines. High-temperature water moves through them under fairly high pressure.

According to current standards, when operating a heating network, coolant leakage per hour should be no more than 0.25% of the total volume.

To reduce heat loss caused by water leaks, it is necessary to regularly carry out preventive measures.

Such measures include:

• Protection of pipes from electrochemical corrosion. To do this, cathodic protection is performed and anti-corrosion agents are applied.
• High-quality water treatment. To slow down pipeline corrosion, the amount of oxygen dissolved in water is reduced.
• Periodic assessment of the residual life of pipes. Thanks to this, it is possible to promptly identify sections of the pipeline that need to be replaced. This can significantly reduce the risk of accidents and, as a result, reduce water losses.

Water balance of heating networks

At any facility that supplies heat, the efficiency of operation is determined every month. In particular, they calculate the balance of water supplied and delivered to end consumers. An imbalance may indicate either significant leaks or incorrect measurements or calculations. For example, when performing calculations, the error of measuring instruments is not taken into account.

If there is a large imbalance, it makes sense to order network diagnostics, which will determine it technical condition and the possibility of further exploitation. Engineering diagnostics is a whole complex of works. A visual inspection of the pipeline is carried out, which allows identifying pockets of corrosion. Using ultrasound diagnostics, pipe thickness measurements are performed.

Hidden leaks are detected through correlation and acoustic diagnostics. An analysis of technical documentation and the necessary engineering calculations are also performed. The customer is presented with a conclusion that indicates the remaining resource, the technical condition of the network and recommendations.

Ministry of Education of the Republic of Belarus

Educational institution

"Belarusian National Technical University"

ABSTRACT

Discipline "Energy Efficiency"

on the topic: “Heat networks. Loss of thermal energy during transmission. Thermal insulation."

Completed by: Shrader Yu. A.

Group 306325

Minsk, 2006

1. Heating network. 3

2. Loss 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. Heating networks.

A heat network is a system of heat pipelines firmly and tightly connected to each other, through which heat is carried out using coolants (steam or hot water) is transported from sources to heat consumers.

The main elements of heating 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, which takes the weight of the pipeline and the forces arising during its operation.

The most critical elements are pipes, which must be sufficiently strong and sealed at maximum pressures and temperatures of the coolant, and have a low coefficient temperature deformations, low internal surface roughness, high thermal resistance walls that contribute to the preservation of heat, the unchanged properties of the material under prolonged exposure to high temperatures and pressures.

The supply of heat to consumers (heating systems, ventilation, hot water supply and technological processes) consists of three interrelated processes: the transfer of heat to the coolant, the transport of the coolant and the use of the thermal potential of the coolant. Heat supply systems are classified according to the following main characteristics: 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 heat supply systems are systems in which three main units are combined and located in the same or adjacent rooms. In this case, the receipt of heat and its transfer to indoor air are combined in one device and located in heated rooms (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 a district heating system, the source of heat is the district boiler house, district heating plant, or combined heat and power plant.

Based on the type of coolant, heat supply systems are divided into two groups: water and steam.

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

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

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

Water heat pipeline systems can be single-pipe or double-pipe (in some cases multi-pipe). The most common is two-pipe system heat supply (hot water is supplied to the consumer through one pipe, and cooled water is returned to the thermal power plant or boiler room through the other, return pipe). There are open and closed heat supply 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. When hot water is fully utilized, a single-pipe system can be used. For closed system characterized by almost complete return of network water to the thermal power plant (or district boiler house).

The following requirements apply to coolants of centralized heating systems: sanitary and hygienic(the coolant should not worsen sanitary conditions in enclosed spaces - average temperature surface area of ​​heating devices cannot exceed 70-80), technical and economic (so that the cost of transport pipelines is minimal, the mass of heating devices is small and ensures minimum consumption fuel for heating premises) and operational (possibility central adjustment heat transfer from consumption systems due to variable outdoor temperatures).

The direction of heat pipes is selected according to a heat map of the area, taking into account geodetic survey materials, plans of existing and planned above-ground and underground structures, data on soil characteristics, etc. The issue of choosing the type of heat pipe (above-ground or underground) is decided taking into account local conditions and technical and economic justifications.

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

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

When choosing a heat pipeline route, one should be guided, first of all, by the conditions of reliability of heat supply, safety of work of operating personnel and the population, and the ability to quickly eliminate problems and accidents.

For the purpose of safety and reliability of heat supply, networks are not laid in common channels with oxygen pipelines, gas pipelines, pipelines compressed air with pressure above 1.6 MPa. When designing underground heat pipelines in order to reduce initial costs, you should choose a minimum number of chambers, constructing them only at installation points for fittings and devices that require maintenance. The number of chambers required is reduced when using bellows or lens compensators, as well as long-stroke axial compensators (dual compensators), natural compensation of temperature deformations.

On a non-roadway, ceilings of chambers and ventilation shafts protruding onto the ground surface to a height of 0.4 m are allowed. To facilitate emptying (drainage) of heat pipes, they are laid with a slope towards the horizon. To protect the steam pipeline from condensate entering from the condensate pipeline during the period when the steam pipeline is stopped or the steam pressure drops, check valves or gates must be installed after the steam traps.

A longitudinal profile is constructed along the heating network route, onto which planning and existing ground marks and the standing level are applied groundwater, existing and projected underground communications, and other structures crossed by the heat pipeline, indicating the vertical elevations of these structures.

2. Loss of thermal energy during transmission.

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

The main problem that arises when solving this problem is identifying the largest components of these losses and choosing the optimal technological solution that can significantly reduce their impact on the efficiency value. Moreover, each specific object (energy saving goal) has a number of characteristic design features and the components of its heat losses are different in magnitude. And whenever it comes to increasing 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 necessary to conduct a detailed examination of the system itself and identify the most significant channels of energy loss. A reasonable solution would be to use only technologies that will significantly reduce the largest unproductive components of energy losses in the system and during minimum costs will significantly increase its efficiency.

2.1 Sources of losses.

For the purpose of analysis, any heat and power system can be divided into three main sections:

1. thermal energy production area (boiler room);

2. area for transporting thermal energy to the consumer (heating network pipelines);

3. area of ​​thermal energy consumption (heated facility).

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

1. Thermal energy production site. Existing boiler room.

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

At the thermal energy production site at normal operation In a boiler unit, there are always three types of main losses: 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 purging and for the own needs of the boiler room (about 3%). The indicated heat loss figures are approximately close for a normal, not new, domestic boiler (with an efficiency of about 75%). More advanced modern boiler units have a real efficiency of about 80-85% and their standard losses are lower. However, they can increase further:

• If routine adjustment of the boiler unit with an inventory of harmful emissions is not carried out in a timely and efficient manner, losses due to underburning of gas may increase by 6-8%;
• Diameter of burner nozzles installed on the boiler unit medium power usually not recalculated for the actual boiler load. 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 the torches to the heating surfaces and an increase of 2-5% in losses due to chemical underburning of the 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 a 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 boiler unit, significantly reducing its operating efficiency.
• If the boiler is not equipped complete set means of control and regulation (steam meters, heat meters, systems for regulating the combustion process and heat load) or if the control means of the boiler unit are not configured optimally, then on average this further reduces its efficiency by 5%.
• If the integrity of the boiler lining is violated, additional air suction into the furnace occurs, which increases losses due to underburning and flue gases by 2-5%
• Use of modern pumping equipment in the boiler room allows you to reduce electricity costs for the boiler room’s own needs by two to three times and reduce the costs of their repair and maintenance.
• Each start-stop cycle of the boiler unit consumes a significant amount of fuel. Perfect option operation of the boiler room - 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 us to minimize losses arising due to power fluctuations and emergency situations in the boiler room.

The sources of additional energy losses in the boiler room listed above are not obvious and transparent for their identification. For example, one of the main components of these losses - losses due to underburning - can only be determined using a chemical analysis of the composition of the flue 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 maintained, there are uncontrolled air suctions into the boiler furnace, the burner device is operating in a non-optimal mode, etc.

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

2. Heat losses during its transportation to the consumer. Existing pipelines of heating networks.

Usually thermal energy, transferred to the coolant in the boiler room, enters the heating main and goes to consumer facilities. The efficiency value of a given section is usually determined by the following:

• Efficiency network pumps, ensuring the movement of 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;
• periodically occurring coolant leaks during emergencies and emergencies.

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

• the use of domestic high-power network pumps with low efficiency almost always leads to significant waste of electricity.
• With a large length of heating pipelines, the quality of thermal insulation of heating mains has a significant impact on the amount of heat losses.
• The hydraulic efficiency of the heating main is a fundamental factor determining the efficiency of its operation. Heat-consuming objects connected to the heating main must be properly spaced so that the heat is distributed evenly over them. Otherwise, thermal energy ceases to be used effectively at consumption facilities and a situation arises with the return of part of the thermal energy through return pipeline to the boiler room. In addition to reducing the efficiency of boiler units, this causes a deterioration in the quality of heating in the buildings most distant 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 a circulation scheme. Presence of a dead-end DHW schemes actually means that about 35-45% of the thermal energy going to DHW needs, is wasted.

Typically, thermal energy losses in heating mains should not exceed 5-7%. But in fact they can reach values ​​of 25% or higher!

3. Losses at heat consumer facilities. Heating and hot water systems of existing buildings.

The most significant components of heat losses in heat power systems are losses at consumer facilities. The presence of such is not transparent and can only be determined after the appearance of a thermal energy meter, the so-called, in the heating station of the building. heat meter. Work experience with a huge amount 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 uneven distribution of heat throughout the object of consumption and irrationality of the internal thermal circuit of the object (5-15%);
• in heating systems associated with a discrepancy between the nature of heating and the current weather conditions (15-20%);
• V 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 of regulation (up to 10-15% of the DHW load).

Total implicit non-productive losses at a consumption facility can amount to up to 35% of the heat load!

The main indirect reason for the presence and increase of the above losses is the lack of heat consumption metering devices at heat consumption facilities. The lack of a transparent picture of a facility’s heat consumption causes a consequent misunderstanding of the importance of taking energy-saving measures there.

3. Thermal insulation

Thermal insulation, thermal insulation, thermal insulation, protection of buildings, thermal industrial installations(or individual nodes thereof), refrigeration chambers, pipelines and other things from unwanted heat exchange with the environment. For example, in construction and thermal power engineering, thermal insulation is necessary to reduce heat losses in environment, in refrigeration and cryogenic technology - to protect equipment from external heat influx. Thermal insulation is ensured by the installation of special fences made of heat-insulating materials (in the form of shells, coatings, etc.) and impeding heat transfer; These thermal protection agents themselves are also called thermal insulation. With predominant convective heat exchange, fencing containing layers of material impermeable to air is used for thermal insulation; for radiant heat transfer - structures made of materials that reflect thermal radiation (for example, 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 transferring heat by 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 coefficient. Increasing the efficiency of thermal insulation is achieved by using highly porous materials and multilayer structures with air gaps.

The task of thermal insulation of buildings is to reduce heat loss during the cold season and ensure relative constancy of indoor temperature throughout the day when the outside temperature fluctuates. By using effective thermal insulation materials for thermal insulation, it is possible to significantly reduce the thickness and weight of enclosing structures and thus reduce the consumption of basic building materials (brick, cement, steel, etc.) and increase the permissible 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. Economic efficiency thermal insulation in industry is often assessed 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 service personnel in hot shops and the prevention of industrial injuries.

3.1 Thermal insulation materials

The main areas of application of thermal insulation materials are insulation of enclosing building structures, technological equipment(industrial furnaces, heating units, refrigerators, etc.) and pipelines.

Not only the heat losses, but also its durability. With the appropriate quality of materials and manufacturing technology, thermal insulation can simultaneously fulfill the role of anti-corrosion protection outer surface steel pipeline. Such materials include polyurethane and its derivatives - 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;

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

· low corrosion activity;

· high electrical resistance;

· alkaline reaction of the environment (pH>8.5);

· sufficient mechanical strength.

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

One of the main requirements for thermal insulation materials for underground heat pipelines is low water absorption. Therefore, highly effective thermal insulation materials with a large content of air pores, which easily absorb moisture from the surrounding soil, are, as a rule, unsuitable for underground heat pipelines.

There are rigid (slabs, blocks, bricks, shells, segments, etc.), flexible (mats, mattresses, bundles, cords, etc.), bulk (granular, powdery) or fibrous thermal insulation materials. Based on the type of main raw material, they are divided into organic, inorganic and mixed.

Organic, in turn, is divided into organic natural and organic artificial. Organic natural materials include materials obtained by processing non-commercial wood and wood waste (fibreboards 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. Organic artificial materials do not have these disadvantages. Very promising materials in this subgroup are foam plastics obtained by foaming synthetic resins. Foam plastics have small closed pores and this differs from porous plastics - also foamed plastics, but having connecting pores and therefore not used as thermal insulation materials. Depending on the recipe and character technological process manufacturing foams can be rigid, semi-rigid and elastic with pores required size; products can be given the desired properties (for example, flammability is reduced). A characteristic feature of most organic heat-insulating materials is low fire resistance, so they are usually used at temperatures no higher than 150 °C.

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

Inorganic materials. A representative of this subgroup is aluminium foil(alfol). It is applied in the form 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. Average thickness mineral wool 6-7 microns, average thermal conductivity coefficient λ=0.045 W/(m*K). These materials are non-flammable and impervious to rodents. They have low hygroscopicity (no more than 2%), but high water absorption (up to 600%).

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

Inorganic materials used as installation materials are made on the basis of asbestos (asbestos cardboard, paper, felt), mixtures of asbestos and mineral binders (asbestodiatoms, 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 materials thermal insulation 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 is a large number of thermal insulation materials from which a choice can be made depending on the parameters and operating conditions various installations, requiring thermal protection.

4. List of used literature.

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

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

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

4. Sokolov V. Ya. “Heating and heating networks” Publishing house M.: Energia, 1982.

5. Thermal equipment and heating networks. G.A. Arsenyev et al. M.: Energoatomizdat, 1988.

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

---IV. Improving the efficiency of energy supply systems
------4.4. Heating network

4.4.3. Methods for reducing losses in heating networks

VIII. Use of renewable energy resources

The main methods are:

• periodic diagnostics and monitoring of the condition of heating networks;
• drainage of canals;
• 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 thermal insulation structures;
• cleaning drains;
• restoration (application) of anti-corrosion, heat and waterproofing coatings in accessible places;
• increasing the pH of network water;
• ensuring high-quality water treatment of make-up water;
• organization of electrochemical protection of pipelines;
• restoration of waterproofing of floor slab joints;
• 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 thermal energy losses in main heating networks based on data from thermal energy metering devices at the thermal station and at consumers for the purpose of prompt decision-making 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 heating points.

Incentives and criteria for personnel must be created. Today's task of the emergency service: come, dig, patch, fill up, leave. The introduction of only one criterion for assessing activity - the absence of repeated ruptures - immediately radically changes the situation (ruptures occur in places of the most dangerous combination of corrosion factors and increased requirements in terms of corrosion protection must be imposed on the replaced local sections of the heating network). Diagnostic equipment will immediately appear, and there will be an understanding that if this heating main is flooded, it needs to be drained, and if the pipe is rotten, then the emergency service will be the first to prove that a section of the network needs to be changed.

It is possible to create a system in which heating network, where the rupture occurred, will be considered as if “sick” and will be admitted for treatment to the repair service, like a hospital. After “treatment”, it will be returned to operational service with a restored resource.

Economic incentives for operating personnel are also very important. 10-20% savings from reducing losses due to leaks (subject to compliance with the network water hardness standards) paid to staff works better than any external investment. At the same time, due to the reduction in the number of flooded areas, losses through insulation are reduced and the service life of networks is increased.

The first thing that the heat supply enterprises of the former CMEA and Baltic countries did after the transition to market relations was to drain the channels of the heating networks. Of all the possible technical measures to reduce costs, this turned out to be the most cost-effective.

It is necessary to radically improve the quality of replacement of heating networks through:

• preliminary examination of the relayed area in order to determine the reasons for failure regulatory period service and training of quality terms of reference for design;
• mandatory project development overhaul with justification for the predicted service life;
• independent instrument testing of the quality of laying heating networks;
• introducing personal responsibility of officials for the quality of gaskets.

The technical problem of ensuring the standard service life of heating networks was solved back in the 50s of the 20th century. due to the use of thick-walled pipes and High Quality construction work, primarily anti-corrosion protection. Now recruiting technical means much wider.

Previously, technical policy was determined by the priority of reducing capital investments. It was necessary to ensure a maximum increase in production at lower costs, so that this increase would compensate for the costs of repairs in the future. In today's situation, this approach is not acceptable. In 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 especially unacceptable when the city population becomes the main payer. In every municipal formation There must be strict control over the quality of the installation of heating networks.

Priorities in spending funds must be changed, most of which is spent today on replacing sections of heating networks in which there were pipe ruptures during operation or summer pressure testing, to preventing the formation of ruptures by monitoring the rate of pipe corrosion and taking measures to reduce it.

We ask you to leave your comments and suggestions on strategy. To read the document, select the section you are interested in.

Energy Saving Technologies and methods

Introduction
This article briefly describes the problems of energy saving that have developed today at the vast majority of domestic facilities for the production, transportation and consumption of thermal energy, offering options for their effective solution.

Existing thermal systems, for the most part, were designed and created without taking into account the opportunities that have appeared on the heat and power market over the past 10 years. The massive development of computing technology led to the emergence at that time of a huge number of technological innovations that radically changed the situation in energy saving. For example, the ability to accurately simulate thermal processes on a computer has led to the emergence of new efficient designs boilers and heating circuits, and advances in the electronics industry have made it possible wide application thermal energy metering devices and highly economical control devices.

Thus, at the end of the twentieth century, energy saving received a large number of effective technologies and new equipment, which made it possible to significantly (up to 50%) increase the reliability and efficiency of existing thermal systems and design new systems that were qualitatively different from existing ones.

Energy saving. Axioms.

To assess the operating efficiency of any system, including heat and power, a generalized physical indicator is usually used - the coefficient of performance (efficiency). The physical meaning of efficiency is the ratio of the amount of useful work (energy) received to the amount expended. The latter, in turn, is the sum of the useful work (energy) received and losses arising in system processes. Thus, increasing the efficiency of the system (and therefore increasing its efficiency) can only be achieved by reducing the amount of unproductive losses that arise during operation. This is the main task of energy saving.

The main problem that arises when solving this problem is identifying the largest components of these losses and choosing the optimal technological solution that can significantly reduce their impact on the efficiency value. Moreover, each specific object - the goal of energy saving - has a number of characteristic design features and the components of its heat losses are different in magnitude. And whenever it comes to increasing 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 necessary to conduct a detailed examination of the system itself and identify the most significant channels of energy loss. A reasonable solution would be to use only technologies that will significantly reduce the largest unproductive components of energy loss in the system and, at minimal cost, significantly increase its operating efficiency.

However, despite the uniqueness in general case factors causing losses in each specific thermal system, domestic facilities have a number characteristic features. They are very similar to each other, which is due to the fact that they were built according to design standards common to the Soyuz at a time when thermal energy cost “a penny.” The characteristic problems and main channels of heat loss in the power systems of “post-Soviet” facilities have been well studied by the specialists of our enterprise. We have worked out the solution to the vast majority of energy saving problems in them in practice, which allows us to analyze, consider the most typical situations with heat losses and propose options for their solution with predicting results, based on our experience of working with similar situations at other facilities.

The study below examines the most characteristic problems existing thermal facilities, describes the most significant channels of unproductive losses of thermal energy in them and offers options for reducing these losses with a preliminary forecast of the results.

Thermal systems. Sources of losses.

For the purpose of analysis, any heat and power system can be divided into 3 main sections:

1. thermal energy production area (boiler room);

2. area for transporting thermal energy to the consumer (heating network pipelines);

3. area of ​​thermal energy consumption (heated facility).

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

1. Thermal energy production site. Existing boiler room.

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

In the thermal energy production area, during normal operation of the boiler unit, there are always three types of main losses: 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 purge and for the own needs of the boiler house ( about 3%). The indicated heat loss figures are approximately close for a normal, not new, domestic boiler (with an efficiency of about 75%). More advanced modern boiler units have a real efficiency of about 80-85% and their standard losses are lower. However, they can increase further:

If routine adjustment of the boiler unit with an inventory of harmful emissions is not carried out in a timely and efficient manner, losses due to underburning of gas may increase by 6-8%; The diameter of the burner nozzles installed on a medium-power boiler unit 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 the torches to the heating surfaces and an increase of 2-5% in losses due to chemical underburning of the 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 a boiler with contaminated surfaces by 4-5% due to an increase in losses with flue gases by this amount. In addition, insufficient operating efficiency of the chemical water treatment system (CWT) leads to the appearance of chemical deposits (scale) on the internal surfaces of the boiler unit, significantly reducing its operating efficiency. If the boiler is not equipped with a full set of control and regulation tools (steam meters, heat meters, systems for regulating the combustion process and heat load) or if the boiler unit control means are not configured optimally, then on average this further reduces its efficiency by 5%. If the integrity of the boiler lining is violated, additional air intakes into the furnace occur, which increases losses from underburning and exhaust gases by 2-5%. The use of modern pumping equipment in the boiler room allows you to reduce electricity costs for the boiler room’s own needs by two to three times and reduce the cost of their repair and service. Each start-stop cycle of the boiler unit consumes a significant amount of fuel. The ideal option for operating a boiler room 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 us to minimize losses arising due to power fluctuations and emergency situations in the boiler room.

The sources of additional energy losses in the boiler room listed above are not obvious and transparent for their identification. For example, one of the main components of these losses - losses due to underburning - can only be determined using a chemical analysis of the composition of the flue 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 maintained, there are uncontrolled air suctions into the boiler furnace, the burner device is operating in a non-optimal mode, etc.

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

An algorithm for increasing the operating efficiency of an existing boiler unit can generally be represented as a sequence of certain actions (in order of effectiveness):

1. Conduct comprehensive examination boiler units, including gas analysis of combustion products. Assess the quality of work of peripheral equipment of the boiler room.

2. Carry out routine adjustment of boilers with an inventory of harmful emissions. Develop operating schedules for boiler units at various loads and measures that will ensure the operation of boiler units only in economical mode.

3. Clean the external and internal surfaces of the boiler units.

4. Equip the boiler room with working control and regulation devices, optimally configure the automation of boiler units.

5. Restore the thermal insulation of the boiler unit by identifying and eliminating uncontrolled sources of air suction into the furnace;

6. Check and possibly upgrade the boiler room’s water treatment system.

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

1. Thermal energy production site. Existing boiler room.

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

In the thermal energy production area, during normal operation of the boiler unit, there are always three types of main losses: 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 purge and for the own needs of the boiler house ( about 3%). The indicated heat loss figures are approximately close for a normal, not new, domestic boiler (with an efficiency of about 75%). More advanced modern boiler units have a real efficiency of about 80-85% and their standard losses are lower. However, they can increase further:

• If routine adjustment of the boiler unit with an inventory of harmful emissions is not carried out in a timely and efficient manner, losses due to underburning of gas may increase by 6-8%;
• The diameter of the burner nozzles installed on a medium-power boiler unit 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 the torches to the heating surfaces and an increase of 2-5% in losses due to chemical underburning of the 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 a boiler with contaminated surfaces by 4-5% due to an increase in losses with flue gases by this amount. In addition, insufficient operating efficiency of the chemical water treatment system (CWT) leads to the appearance of chemical deposits (scale) on the internal surfaces of the boiler unit, significantly reducing its operating efficiency.
• If the boiler is not equipped with a full set of control and regulation tools (steam meters, heat meters, systems for regulating the combustion process and heat load) or if the boiler unit control means are not configured optimally, then on average this further reduces its efficiency by 5%.
• If the integrity of the boiler lining is violated, additional air suction into the furnace occurs, which increases losses due to underburning and flue gases by 2-5%
• The use of modern pumping equipment in a boiler room allows you to reduce electricity costs for the boiler room’s own needs by two to three times and reduce the costs of their repair and maintenance.
• Each start-stop cycle of the boiler unit consumes a significant amount of fuel. The ideal option for operating a boiler room 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 us to minimize losses arising due to power fluctuations and emergency situations in the boiler room.

The sources of additional energy losses in the boiler room listed above are not obvious and transparent for their identification. For example, one of the main components of these losses - losses due to underburning - can only be determined using a chemical analysis of the composition of the flue 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 maintained, there are uncontrolled air suctions into the boiler furnace, the burner device is operating in a non-optimal mode, etc.

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

2. Heat losses during its transportation to the consumer. Existing pipelines of heating networks.

Typically, the thermal energy transferred to the coolant in the boiler room enters the heating main and goes to consumer facilities. The efficiency value of a given section is usually determined by the following:

• Efficiency of network pumps that ensure the movement of 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;
• periodically occurring coolant leaks during emergencies and emergencies.

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

• the use of domestic high-power network pumps with low efficiency almost always leads to significant waste of electricity.
• With a large length of heating pipelines, the quality of thermal insulation of heating mains has a significant impact on the amount of heat losses.
• The hydraulic efficiency of the heating main is a fundamental factor determining the efficiency of its operation. Heat-consuming objects connected to the heating main must be properly spaced so that the heat is distributed evenly over them. Otherwise, thermal energy ceases to be used effectively 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 boiler units, this causes a deterioration in the quality of heating in the buildings most distant 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 a circulation scheme. The presence of a dead-end DHW circuit actually means that about 35-45% of the thermal energy used for DHW needs is wasted.

Typically, thermal energy losses in heating mains should not exceed 5-7%. But in fact they can reach values ​​of 25% or higher!

3. Losses at heat consumer facilities. Heating and hot water systems of existing buildings.

The most significant components of heat losses in heat power systems are losses at consumer facilities. The presence of such is not transparent and can only be determined after the appearance of a thermal energy meter, the so-called, in the heating station of the building. heat meter. Experience of working 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 uneven distribution of heat throughout the object of consumption and irrationality of the internal thermal circuit of the object (5-15%);
• in heating systems associated with a discrepancy between the nature of heating and current weather conditions (15-20%);
• in hot water 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 of regulation (up to 10-15% of the DHW load).

Total implicit non-productive losses at a consumption facility can amount to up to 35% of the heat load!

The main indirect reason for the presence and increase of the above losses is the lack of heat consumption metering devices at heat consumption facilities. The lack of a transparent picture of a facility’s heat consumption causes a consequent misunderstanding of the importance of taking energy-saving measures there.

3. Thermal insulation

Thermal insulation, thermal insulation, thermal insulation, protection of buildings, thermal industrial installations (or individual units thereof), refrigeration chambers, pipelines and other things from unwanted heat exchange with the environment. 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 the outside. Thermal insulation is ensured by the installation of special fences made of heat-insulating materials (in the form of shells, coatings, etc.) and impeding heat transfer; These thermal protection agents themselves are also called thermal insulation. With predominant convective heat exchange, fencing containing layers of material impermeable to air is used for thermal insulation; for radiant heat transfer - structures made of materials that reflect thermal radiation (for example, 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 transferring heat by 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 coefficient. Increasing the efficiency of thermal insulation is achieved by using highly porous materials and constructing multilayer structures with air layers.

The task of thermal insulation of buildings is to reduce heat loss during the cold season and ensure relative constancy of indoor temperature throughout the day when the outside temperature fluctuates. By using effective thermal insulation materials for thermal insulation, it is possible to significantly reduce the thickness and weight of enclosing structures and thus reduce the consumption of basic building materials (brick, cement, steel, etc.) and increase the permissible dimensions of prefabricated elements.