Heat supply of the residential area from the hot water boiler house

Introduction.

Energy is the leading industry of the modern industrially developed national economy of the country. The concept of energy covers a wide range of installations for the production, transport and use of electric and thermal energy, energy of compressed gases and other energy carriers.

In our country, whose main territory is located in a harsh climatic zone, providing consumers with thermal energy is also of great importance. The main consumption of thermal energy in the urban economy falls on industry (about 70%). The most heat-consuming include: chemical and petrochemical, mechanical engineering and metalworking, fuel and food industries.

At the industrial enterprise, thermal energy is distributed to technological processes, heating, ventilation and hot water supply. In housing and communal services, the main consumers of thermal energy are building heating systems.

Heat supply. Heat supply systems.

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

There are local and centralized heat supply. The local heating system serves one or more buildings, the centralized system serves a residential or industrial area. In the USSR, centralized heat supply acquired the greatest importance. Its main advantages over local ones are a significant reduction in fuel consumption and operating costs (for example, due to automation of boiler plants and increasing their efficiency); possibility of using low-grade fuel; reduced degree of air basin pollution and improved sanitary condition of populated areas.

The heat supply system of the building is designed to provide the thermal energy (heat) of its engineering systems, which require the supply of heated coolant for its functioning. In addition to traditional systems (heating and hot water supply), other heat-consuming systems (ventilation and air conditioning, heated floors, swimming pool) can be provided in a modern civilian building.

The district heat supply system includes a heat source, a heat network and heat consuming plants connected to the network through heat points. Heat sources with centralized heat supply can be thermal power plants (CHP), which carry out the combined generation of electric and thermal energy; high-power boiler plants generating only thermal energy; devices for utilization of thermal wastes of industry; geothermal heat plants. In local heat supply systems, heat sources are furnaces, hot water boilers, water heaters (including solar ones), etc. Heat carriers in district heat supply systems are usually water with a temperature of 150 ° C and steam under a pressure of 0.71.6 MPa (716 at). Water serves mainly for coating communal household, and steam - technological loads. The choice of temperature and pressure in heat supply systems is determined by consumer requirements and economic considerations. As heat transportation range increases, economically justified increase of coolant parameters increases. The distance to which heat is transported in modern district heating systems reaches several tens of km. The costs of conventional fuel per unit of heat released to the consumer are determined mainly by the efficiency of the heat supply source. The development of heat supply systems is characterized by an increase in the capacity of the heat source and the unit capacities of the installed equipment. The thermal capacity of modern CHPs reaches 2-4 Gcal/h, district boiler houses 300-500 Gcal/h. In some heat supply systems, several heat sources work together on common heat networks, which increases the reliability, maneuverability and cost-effectiveness of heat supply.

At the choice of the coolant, the heat supply is water and steam. As a coolant, heated water is usually used at present. Water vapor for heat supply purposes, due to numerous shortcomings, is used extremely rarely, mainly in production buildings where steam is required for technological needs. The heat source for the local or decentralized water heat supply system is a hot water boiler house located directly in or near the building. With centralized water heat supply, high-temperature water enters the building from a remote heat source: a thermal power plant (CHP) or a district thermal station (RTS).

Depending on the heat supply source, the schemes and equipment of the boiler house or local heat station of the building are distinguished, from where heat is supplied to the engineering systems, their control and control.

According to the connection schemes of heating plants, dependent and independent heat supply systems are distinguished. In dependent systems, the coolant from the heat network enters directly to the heating plants of consumers, in independent ones - to the intermediate heat exchanger installed in the thermal point, where it heats the secondary heat carrier circulating in the local consumer installation. In independent systems, consumer installations are hydraulically isolated from the thermal network. Such systems are mainly used in large cities - in order to improve the reliability of heat supply, as well as in cases where the mode in the heat network is unacceptable for heat-consuming plants according to the conditions of their strength or when the static pressure created by the latter is unacceptable for the heat network (such, for example, heating systems of high-rise buildings).

Depending on the connection scheme of hot water supply plants, closed and open heat supply systems are distinguished. In closed systems, water from the water supply line, heated to the required temperature by water from the heat network in heat exchangers installed in heat points, is supplied to the hot water supply. In open systems, water is supplied directly from the heat network (direct water discharge). Leakage of water due to leaks in the system, as well as its flow rate for the water intake, is compensated by additional supply of the corresponding amount of water to the heat network. To prevent corrosion and scale formation on the internal surface of the pipeline, water supplied to the heat network undergoes water treatment and deaeration. In open systems, water must also meet drinking water requirements. The choice of the system is determined mainly by the presence of a sufficient amount of drinking water, its corrosive and boiling properties. In the USSR, systems of both types became widespread.

According to the number of pipelines used to transfer the coolant, there are single-, two - and multi-tube heat supply systems. Single-tube systems are used when the coolant is fully used by consumers and is not returned (for example, in steam systems without condensate return and in open water systems where all water coming from the source is disassembled for hot water supply to consumers). In double-tube systems, the coolant is completely or partially returned to the heat source, where it is heated and replenished. Multi-tube systems are used when it is necessary to separate separate types of heat load (for example, hot water supply), which simplifies the regulation of heat release, operation mode and methods of connecting consumers to heat networks. In the USSR, two-tube heat supply systems became predominantly widespread.

Control of heat release in heat supply systems (daily, seasonal) is carried out both in the heat source and in heat consuming plants. In water heat supply systems, the so-called central high-quality control of heat supply is usually carried out according to the main type of heat load - heating or hot water supply. It consists in changing the temperature of the coolant supplied from the heat supply source to the heat network in accordance with the accepted temperature schedule (that is, the dependence of the required water temperature in the network on the outside air temperature). Central quality regulation is complemented by local quantity in heat points; the latter is most common in hot water supply and is usually carried out automatically. In steam heat supply systems, local quantitative control is mainly carried out; steam pressure in heat supply source is kept constant, steam flow rate is controlled by consumers.

Quite often, the scheme of the local heat station of the building with centralized heat supply can be combined, when, for example, the water heating system is connected to the external heat networks according to an independent scheme, and other systems, for example, ventilation and air conditioning, according to a dependent scheme.

Heating - centralized heat supply based on combined production of electricity and heat at thermal power plants. Thermodynamic efficiency of power generation according to the heating cycle is due to the exclusion, as a rule, of heat removal into the environment, which is inevitable in power generation according to the condensation cycle. Due to this, the specific (per 1 kWh) fuel consumption for electricity generation is significantly reduced (by 4050%). In terms of development, heating Russia occupies a leading position in the world. The capacity of heating turbines installed on thermal power plants is about 1/3 of the capacity of steam turbines of all thermal power plants in the country. Due to the combined production of electricity and heat in 1974. in the USSR, fuel savings of more than 30 million tons were obtained.

Some problems of heating in Russia.

The development of heating in Russia has great traditions. 75 years ago, in November 1924, the first heat pipeline from the Leningrad State Power Plant No. 3 was commissioned (today it is the Ginter CHPP of Lenenergo JSC).

This heat pipeline for the first time in Russia supplied heat to building No. 96 on the embankment of the Fontanka River. This date is considered the beginning of the development of heating in Russia. Throughout its existence, this industry has contributed to and still contributes to the saving of large volumes of fuel and economic resources due to the high efficiency of combined production of electric and thermal energy at CHP, compared to their separate production.

Currently, 70% of all power plants in Russia are thermal, of which more than half are thermal power plants. The total capacity of the CHPP is 60 GW, electricity production is 521 billion kWh, heat is 527 million. Gkal (according to the results of 1997). Fuel economy as a result of combined electricity and heat production amounted to 24 million tons. This is both an economic and environmental effect. In the volume of commercial products, heat energy, which is sold by CHP members of RAO UES of Russia, is about 30%.

In theory, fuel economy in combined power and heat production can be estimated at 30%. However, with the existing heat transport system with large heat losses, the cost of heat delivery makes it very expensive for the end user. Heat losses reaching 3040% occur mainly not in highways, but in distribution networks - more than 90%. Fuel economy in combined power and heat production should be substantially greater than the cost of transportation. Now this difference is small - about 1.5 billion rubles in the whole country.

The underestimation of this area of ​ ​ work (heat transport) led to the fact that the end user has heat prices from the CHP and the boiler house at the same level. Therefore, some consumers (industrial, communal), if there is a district heating system, build autonomous boiler houses. This can negatively affect the efficiency of the CHP and the environmental situation.

Thus, the question arises about the need to adjust the development of the CT system so that it is not only more efficient than autonomous heat sources, but also more profitable for the end user. In particular, by selling heat to municipal services on the verge of main and distribution heat pipelines, it is necessary to create economic conditions that would ensure the interest of these services in improving the quality of their heating networks and reducing heat losses in them.

The annual commissioning of 3 million m2 of new housing in Moscow requires a new approach to the problem of energy supply in the capital.

There are several solutions, of which the most rational is the transition to energy-saving technologies that save primary fuel energy - from generation to consumption and payments.

Higher selling prices for gas fuel, which is processed into useful electrical and thermal energy with low efficiency, lead to an even greater increase in the cost of electricity and heat.

Let us imagine the peak capacity of the existing traditional energy system, which should provide 3 million square meters. m of new buildings, taking into account the fact that the use of the most modern energy-saving technologies in construction allows to reduce the total (heat + electricity) peak consumption in new residential buildings to 50 W/m2. In this case, additional peak power for electric and thermal energy of 150 MW is required annually. Of these, about 80 MW of thermal power in recent years is provided by RTS and roof boiler houses, and about 70 MW of electrical power is provided by the existing Mosenergo CHP.

The efficiency factor (efficiency) of the Moscow power system for electric power generation is on average 20% (Mosenergo report for 1999). In this case, the generation of the specified capacity (70 MW) will require the combustion of natural gas with an equivalent capacity of 350 MW. The remaining required 80 MW of thermal power will be provided by RTAs operating with an average efficiency of 0.85 and a heating system with CTP (CPD0.6). The total efficiency of this energy saving method is 0.51 (0,850,6 = 0.51). The production of the specified 80 MW will require the use of natural gas with a thermal capacity of 160 MW.

Thus, 510 MW (350 MW + 160 MW) of natural gas thermal capacity is required to provide the required 150 MW peak capacity. The total efficiency of the used power supply system consists of no more than 0.294 or about 30% (150 MW: 510 MW - 0.294).

As a result of providing the newly introduced housing with only electric energy from the Mosenergo networks, and thermal energy from local RTS with heat trays and CTP connected to them, the annual gas consumption will increase by 307 million cubic meters, and about 5070% of such valuable fuel as natural gas will be burned in the "wind."

The use of individual heat stations (ITPs) and roof boiler houses mitigates the situation, but does not radically change it due to the increase in the need for electric energy with unclaimed thermal energy of Mosenergo.

Decentralization of energy sources reduces peak fuel consumption by about 4 times compared to the option of using the capabilities of Mosenergo, and with the option of roof boiler houses - by 2 times.

According to experts, in Russia one ruble invested in energy conservation gives three rubles of return. Budgetary savings in decentralized electricity and heat supply are provided by:

• refusal to build relatively expensive (capital-intensive) RTS, accident, ITP, TP, power lines and, often, roof boiler rooms;

• sharp reduction in the cost of utilities due to a significant reduction in their length and elimination of heating lines with a corresponding decrease in operating and repair costs;

• reduction of specific consumption of natural gas for generation of electric and thermal energy due to higher efficiency of aggregates and LFR of gas fuel and, accordingly, economy of this type of fuel.

One of the important directions of improving heating systems and ensuring maximum fuel economy is the creation of heat supply systems based on mini-CHP using gas piston plants.

When deciding on the construction of its own station, it is necessary to take into account the advantages of mini-CHP compared to traditional steam pipe or gas turbine stations:

• lower cost of heat and electricity generation

• high efficiency (up to 94%)

• Relatively low investment

• Short planning and construction time

• susceptibility to variable loads

• lower cost of heat and electricity transmission and distribution

• low level of harmful emissions

• easy operation

• lower operating costs

To reduce capital costs for the construction of the building for mini-CHP, the installation of power units is supposed to be carried out in existing boiler buildings.

Mini - CHP. Evaluation of cogeneration profitability.

Mini-CHP is a power plant with combined generation of electric energy and heat (cogenerator), located in close proximity to the consumer. As a source of energy in a mini-CHP internal combustion engine (ICE).

Cogeneration is an energy technology - economic independence and a reduction in heat and electricity costs by 2.8 times. Cogeneration is a highly efficient use of a primary energy source - gas, to obtain two forms of useful energy - thermal and electrical. The main advantage of the cogenerator over conventional thermal power plants is that the energy conversion here is more efficient. In other words, the cogeneration system allows the use of heat which is usually simply lost. At the same time, the need for purchased energy is reduced by the amount of heat and electric energy generated, which helps to reduce production costs. The use of the cogenerator reduces energy costs by approximately $100/kW of the installed electric power of the cogenerator.

The cogenerator consists of a gas engine, a generator, a heat extraction system and a control system. Heat is removed from the gas exhaust, oil cooler and engine coolant. At the same time, on average, per 100 kW of electric power, the consumer receives 150 160 kW of thermal power in the form of hot water (90 ° C129 ° C) for heating and hot water supply.

Cogenerators successfully cover the demand of consumers for cheap electric and thermal energy. Independent electricity supply entails a number of advantages.

Position of cogenerators in the Russian energy saving market.

The use of cogenerators in the central part of large cities allows you to effectively complement the energy saving market, without reconstructing old congested networks. At the same time, the quality of electrical and thermal energies significantly increases. The autonomous operation of the cogenerator allows providing consumers with electricity with stable parameters in frequency and voltage, thermal energy with stable parameters in temperature and high-quality hot water. As potential facilities for the use of cogeneration in Russia are industrial production, plants, oil refineries, hospitals, housing facilities, their own needs of gas pumping stations, compression stations, boiler houses, etc.

As a result of the introduction of combined sources, it is possible to solve the problem of providing consumers with heat and electricity without additional construction of powerful power transmission lines and heat pipelines. The proximity of sources to consumers will significantly reduce the loss of energy transmission and improve its quality, and therefore increase the utilization rate of natural gas energy.

Position of cogenerators on the electric power market.

Cogenerators fit well into the electrical circuit of individual consumers and into the city's electrical networks while working in parallel with the network. Cogenerators cover the lack of generating capacity in the center of cities. The advent of cogenerators allows you to unload the electric networks of the city center, ensure stable quality of electricity and make it possible to connect new consumers of appropriate capacity.

Competitive analysis of the Russian energy saving market.

The conditions imposed on suppliers of electricity and thermal energy to connect to electrical and thermal networks often lead to significant irretrievable costs and even to a revision of these same connections. The specific cost of connecting to energy networks has already reached, and at a number of facilities exceeds, the specific cost of a cogeneration plant with the same energy parameters. A significant difference between the capital costs of energy saving from the networks and energy saving from the own source is that the capital costs associated with the purchase of the cogenerator are reimbursed, and the capital costs of connecting to the networks are irrevocably lost when transferring the newly built substations to the balance of energy companies.

Capital costs for the use of the cogenerator are compensated by the low cost of energy as a whole. Typically, full capital and operating cost recovery occurs after the cogenerator has been in operation for three to four years. Moreover, energy savings from the cogenerator reduce the annual costs of electricity and heat supply compared to power supply from power systems by about $100 for each kW of the nominal electric power of the cogenerator, in the case when the cogenerator operates in the basic power generation mode (at 100% load year-round). This is possible when the generator supplies a load in a continuous cycle of operation or if it operates in parallel with the network. The latter solution is also beneficial for electric and thermal networks.

The electric grid will be interested in connecting cogenerators to its networks, as it acquires additional generating capacity without capital investments in the construction of the power plant. In this case, the power system buys cheap electricity for its sequential implementation at a more profitable tariff. Heat networks are able to reduce heat production and purchase cheap heat for its sale to nearby consumers through existing heat networks.

Output:

Possible heat supply options:

a) Clean hot water boiler room.

Such a boiler house is unpromising in terms of system economy due to increased fuel requirements and the need to address environmental problems. High maintenance costs.

b) City CHP.

Since this project considers a small settlement (quarter), this type of heat supply will be too expensive and unprofitable, due to large losses in pipelines. The city CHP is located far away, pulling the heating system to a small quarter is laborious and uneconomical. The CHP equipment is mentally and physically obsolete for the most part, the quality of repairs is at a low level, heat transport communications constantly fail and require the replacement of pipes and qualitatively different gaskets from source to consumer with reliable insulation of networks. Accidents on long main and distribution networks from the CHP dramatically reduce the reliability of heat supply to consumers of all categories: housing and communal and industrial enterprises of various profiles. There may be cases of long-term disconnection of consumers from thermal and electrical networks during the heating period.

c) Cogeneration boiler house with small boilers of high capacity.

This type of heat supply is very attractive from an economic and environmental point of view. The simultaneous generation of heat and electricity has a number of advantages. The main ones are:

• short construction time;

• improving the reliability of heat supply to consumers;

• reduction of thermal control inertia;

• reduction of losses in heat networks.

Electricity is generated from its own boiler house, it becomes possible to sell electricity to nearby consumers, therefore, tariffs will be lower. The disadvantages include the difficulty of placing them, the need to address the issue of the supply of excess electricity to the general grid and the large initial construction costs, which are covered in a short time.

This project considers the heat supply of the residential quarter from the hot water boiler house and the power supply of the nearby enterprise in Tula. The economic comparison of two heat supply options is given:

1) from the classic hot water boiler house;

2) from the boiler house with cogeneration.