CN103629724B - Significantly reduce the system of cogeneration of heat and power central heating temperature - Google Patents

Abstract

A system that greatly reduces the central heating temperature of combined heat and power generation. By introducing an absorption heat exchange unit and a multi-stage electric drive heat pump, the heat source is used as a power source and heat exchange for many times, which improves the utilization efficiency of the steam heat source and makes it more efficient. Provide heat for users; introduce solar collectors, use solar energy as a clean energy to heat up the return water of the primary network, save energy and protect the environment; in addition, add heat exchangers to the thermal power plant, and use the low-grade heat source in the condenser to increase the return water of the primary network. At the same time, the steam double-effect absorption heat pump, steam single-effect absorption heat pump, and steam large temperature difference absorption heat pump are introduced to recover low-grade heat step by step, effectively utilize the exhaust steam in the steam turbine, and improve energy utilization efficiency. The water supply temperature of the primary network is reduced to 90°C, which saves the heating and steam extraction of the thermal power plant and increases the power generation capacity of the thermal power plant; at the same time, the reduction of the heating water temperature saves the amount of thermal insulation materials and reduces the heat loss of the heating pipeline.

Description

A system that significantly reduces the temperature of district heating for combined heat and power generation

technical field

The invention belongs to the field of combined heat and power heat supply, and in particular relates to a system for greatly reducing the temperature of centralized heat supply for combined heat and power.

Background technique

In recent years, with the increase of urban heating area in my country and the construction of industrial plants and production lines, the heat consumption in my country has grown rapidly. From the analysis of heating methods, there are mainly the following heating methods for residents in my country: combined heat and power generation, central heating in small and medium-sized regional boiler rooms, small household gas-fired water heaters, household coal-fired furnaces, etc. Among them, the cogeneration method is a comprehensive energy utilization technology that uses high-grade thermal energy of fuel to generate electricity and then supplies low-grade thermal energy for heating. At present, the average power generation efficiency of 3 million kilowatt thermal power plants in my country is 33%, while the power generation efficiency of thermal power plants can reach 20% when heating, and more than 70% of the remaining 80% of heat can be used for heating. The 10,000-kilojoule fuel can generate 2,000 kilojoules of electricity and 7,000 kilojoules of heat by cogeneration. However, if ordinary thermal power plants are used to generate electricity, the 2000 kilojoules of electricity will consume 6000 kilojoules of fuel. Therefore, if the electricity produced by cogeneration is deducted from the fuel consumption according to the power generation efficiency of ordinary power plants, the remaining 4,000 kilojoules of fuel can generate 7,000 kilojoules of heat. In this sense, the heating efficiency of thermal power plants is 170%, which is about twice that of small and medium-sized boiler rooms. Therefore, when conditions permit, the heating method of combined heat and power should be developed first. Nevertheless, there are still some problems in heat supply in the way of heat and power cogeneration, for example, a large amount of energy is wasted by exhaust steam from the steam turbine directly entering the cooling tower, so that a large amount of latent heat of vaporization is not fully utilized. At the same time, the steam required for heating greatly reduces the power generation efficiency and so on. On the other hand, high-temperature steam heating pipes need a large amount of thermal insulation materials to reduce heat loss; in the case of high heating temperature, even though more thermal insulation materials are used, greater heat loss will be caused.

Contents of the invention

Aiming at the problem that a large amount of latent heat of vaporization in the exhaust steam of the steam turbine cannot be fully utilized, and the disadvantage of a large amount of heat loss in the heating pipeline, the present invention provides a system for greatly reducing the temperature of central heating for combined heat and power generation.

The technical scheme that the present invention adopts for solving technical problems is:

In a thermal power plant, part of the high-temperature steam in the steam turbine drives the generator to generate electricity, and the other part of the high-temperature steam is respectively input to the steam double-effect absorption heat pump, steam single-effect absorption heat pump, and steam large temperature difference absorption heat pump, as the absorption heat pump units at all levels The power source participates in heat exchange;

The exhaust steam in the steam turbine enters the condenser, and part of the hot water with a heat exchange rate of 40°C is input into the heat exchanger to exchange the heat of the return water of the primary network at 15°C to 25°C, and the other part is connected to steam in parallel Double-effect absorption heat pumps, steam single-effect absorption heat pumps, and steam large-temperature-difference absorption heat pumps are used as low-temperature heat sources for absorption heat pump units at all levels, and return to the condenser after heat exchange; hot water at 25°C enters the steam double-effect absorption The heat pump, steam single-effect absorption heat pump, and steam large temperature difference absorption heat pump are heated to 55°C, 70°C, and 90°C respectively, and finally the hot water at 90°C is input to the absorption heat exchange unit as primary network water supply;

In the heat exchange station, the primary network water supply at 90°C is input into the absorption heat exchange unit as the power source, and continues to be used as the low-temperature heat source of the absorption heat exchange unit after cooling down. As a low-temperature heat source, the temperature drops to 25 ℃, the 25℃ hot water is then used as a low-temperature heat source to input to the evaporator side of the multi-stage electric drive heat pump so that the condenser side can provide users with 60 ℃ hot water heating, and the evaporation from the multi-stage electric drive heat pump The 5°C primary network return water discharged from the side of the collector is input into the solar collector to heat the temperature of the primary network return water to 15°C, and then enters the thermal power plant system through the heat exchanger.

Absorption heat pumps at all levels are driven by steam turbines around 0.3MPa for heating and extraction.

The beneficial effects of the present invention are:

The water supply temperature of the primary network is reduced to 90°C, which saves the heating and steam extraction of the thermal power plant and increases the power generation capacity of the thermal power plant; at the same time, the reduction of the heating water temperature saves the amount of insulation materials and reduces the heat loss of the heating pipeline.

The absorption heat exchange unit and multi-stage electric drive heat pump are introduced, and the heat source is used as a power source and heat exchange many times, which improves the utilization efficiency of the steam heat source and better provides heat for users;

Introduce solar heat collectors, use solar energy as a clean energy to heat up the return water of the primary network, save energy and protect the environment;

In addition, a heat exchanger is added to the thermal power plant, and the low-grade heat source in the condenser is used to increase the return water temperature of the primary network. At the same time, a steam double-effect absorption heat pump, a steam single-effect absorption heat pump, and a steam large temperature difference absorption heat pump are introduced to recover step by step The low-grade heat effectively utilizes the exhaust steam in the steam turbine and improves energy utilization efficiency.

This system provides the power generation efficiency of the power plant above 30%.

Description of drawings

Fig. 1 is a schematic diagram of the present invention.

In the figure: 1. Steam turbine, 2. Generator, 3. Condenser, 4. Cooling tower, 5. Heat exchanger, 6. Steam double-effect absorption heat pump, 7. Steam single-effect absorption heat pump, 8. Steam large Temperature difference absorption heat pump, 10. Absorption heat exchange unit, 11. Multi-stage electric drive heat pump, 12. Solar collector, 13. User

detailed description

In a thermal power plant, a part of the high-temperature steam in the steam turbine 1 drives the generator 2 to generate electricity, and the other part of the high-temperature steam is respectively input to the steam double-effect absorption heat pump 6, the steam single-effect absorption heat pump 7, and the steam large temperature difference absorption heat pump 8, as The power source of the absorption heat pump unit participates in heat exchange;

The exhaust steam in the steam turbine 1 enters the condenser 3, and part of the hot water with a heat exchange rate of 40°C is input to the heat exchanger 5 to exchange the heat of the 15°C primary network return water to 25°C, and the other part is connected in parallel Connect steam double-effect absorption heat pump 6, steam single-effect absorption heat pump 7, and steam large temperature difference absorption heat pump 8, as the low-temperature heat source of absorption heat pump units at all levels, and return to condenser 3 after heat exchange; 25℃ hot water Enter the steam double-effect absorption heat pump 6, steam single-effect absorption heat pump 7, and steam large temperature difference absorption heat pump 8 in turn to heat to 55°C, 70°C, and 90°C respectively, and finally the hot water at 90°C is input to the absorption as primary network water supply type heat exchange unit 10;

In the heat exchange station, the primary network water supply at 90°C is input into the absorption heat exchange unit 10 as the power source, and continues to be used as the low-temperature heat source of the absorption heat exchange unit 10 after performing work and cooling down, and the temperature decreases after heat exchange as a low-temperature heat source The temperature is 25°C, and the 25°C hot water is then used as a low-temperature heat source to be input to the evaporator side of the multi-stage electric drive heat pump 11 so that the condenser side can provide users with 60°C hot water heating, and the multi-stage electric drive heat pump The 5°C primary network return water discharged from the evaporator side in 11 is input into the solar collector 12 to heat the primary network return water temperature to 15°C, and then enters the thermal power plant system through the heat exchanger 5.

Absorption heat pumps at all levels are driven by steam turbines around 0.3MPa for heating and extraction.

The present invention is not limited to this embodiment, and any equivalent ideas or changes within the technical scope disclosed in the present invention are listed in the protection scope of the present invention.

Claims (1)

1. significantly reduce a system for cogeneration of heat and power central heating temperature, it is characterized in that:

In steam power plant, in steam turbine (1), a part of high-temperature steam drives generator (2) generating, another part high-temperature steam is input to steam double-effect absorption heat pump (6), steam single-effective absorption heat pump (7), the large temperature difference absorption heat pump (8) of steam respectively, and the power source as absorption type heat pump assembly at different levels participates in heat exchange;

Exhaust steam in steam turbine (1) enters into condensing engine (3), wherein a part of heat exchange is that the hot water of 40 DEG C to be input to a secondary net backwater heat exchange of 15 DEG C in heat exchanger (5) is 25 DEG C, another part accesses steam double-effect absorption heat pump (6), steam single-effective absorption heat pump (7), the large temperature difference absorption heat pump (8) of steam in parallel, as the low-temperature heat source of absorption type heat pump assembly at different levels, return in condensing engine (3) after heat exchange; 25 DEG C of hot water enters steam double-effect absorption heat pump (6) successively, steam single-effective absorption heat pump (7), the large temperature difference absorption heat pump (8) of steam are heated to 55 DEG C, 70 DEG C, 90 DEG C respectively, and the hot water of last 90 DEG C supplies water as a secondary net and is input to absorption heat exchange unit (10);

In heat exchange station, one secondary net of 90 DEG C supplies water input absorption heat exchange unit (10) as power source, the low-temperature heat source as this absorption heat exchange unit (10) is continued after acting cooling, 25 DEG C are reduced to as temperature after low-temperature heat source heat exchange, this hot water of 25 DEG C is input to the vaporizer side in multistage electric drive heat pump (11) as low-temperature heat source again to make condenser side provide the hot water heating of 60 DEG C for user, be input in solar thermal collector (12) from a secondary net backwater of 5 DEG C of the vaporizer side discharge multistage electric drive heat pump (11) and a secondary net return water temperature is heated to 15 DEG C, then entered in steam power plant's system by heat exchanger (5).