阅读说明：本技术 一种回收烟气中潜热的火电系统储能调峰系统及工作方法 (Thermal power system energy storage peak regulation system for recovering latent heat in flue gas and working method ) 是由 张一帆 李红智 高炜 李凯伦 张磊 于 2021-03-30 设计创作，主要内容包括：本发明公开了一种回收烟气中潜热的火电系统储能调峰系统及工作方法,该系统包括烟道、烟气冷却器、水泵、水-二氧化碳换热器、回热器、压缩机、电动机、二氧化碳-颗粒/熔盐换热器、节流阀、冷罐、泵、和热罐；本发明结合二氧化碳热泵冷端温度低、热端温度高、COP高的优势,首先将饱和湿烟气中的低品位余热进行提质回收,随后通过大型储热系统将提质后的热量进行存储并实现高效灵活应用。该发明可有效解决火电机组脱硫后的饱和湿烟气中大量低品位余热利用难的问题,回收了烟气中的大量低品位余热的同时,还可回收大量水资源；另外,可以根据火电机组调峰的需求,利用储热系统进行机组辅助调峰,取代能效不高的电锅炉、热水储罐等。(The invention discloses a thermal power system energy storage peak shaving system for recovering latent heat in flue gas and a working method thereof, wherein the system comprises a flue, a flue gas cooler, a water pump, a water-carbon dioxide heat exchanger, a heat regenerator, a compressor, a motor, a carbon dioxide-particle/molten salt heat exchanger, a throttle valve, a cold tank, a pump and a hot tank; the invention combines the advantages of low temperature at the cold end, high temperature at the hot end and high COP (coefficient of performance) of the carbon dioxide heat pump, firstly carries out upgrading and recycling on low-grade waste heat in saturated wet flue gas, and then stores upgraded heat through a large heat storage system and realizes efficient and flexible application. The method can effectively solve the problem that a large amount of low-grade waste heat in the saturated wet flue gas after desulfurization of the thermal power generating unit is difficult to utilize, and can recover a large amount of water resources while recovering a large amount of low-grade waste heat in the flue gas; in addition, the heat storage system can be used for carrying out auxiliary peak shaving of the thermal power generating unit according to the peak shaving requirement of the thermal power generating unit, and an electric boiler, a hot water storage tank and the like with low energy efficiency are replaced.)

1. A thermal power system energy storage peak regulation system for recovering latent heat in flue gas is characterized by comprising a flue gas cooling loop, a carbon dioxide heat pump loop and an energy storage loop; the flue gas cooling loop and the carbon dioxide heat pump loop exchange heat through a water-carbon dioxide heat exchanger (4); the carbon dioxide heat pump loop and the energy storage loop exchange heat through a carbon dioxide-particle/molten salt heat exchanger (8).

2. The thermal power system energy storage peak shaving system for recovering latent heat in flue gas as claimed in claim 1, wherein: the flue gas cooling loop comprises a flue (1), a flue gas cooler (2), a water pump (3) and a water-carbon dioxide heat exchanger (4); wherein the flue gas cooler (2) is arranged in the flue (1) to realize the heat exchange of cooling water and flue gas; the outlet of the water pump (3) is sequentially connected with the hot side of the water-carbon dioxide heat exchanger (4) and the cold side of the flue gas cooler (2) and then connected with the inlet of the water pump (3) to form closed cooling water circulation.

3. The thermal power system energy storage peak shaving system for recovering latent heat in flue gas as claimed in claim 1, wherein: the carbon dioxide heat pump loop comprises a water-carbon dioxide heat exchanger (4), a heat regenerator (5), a compressor (6), a motor (7), a carbon dioxide-particle/molten salt heat exchanger (8) and a throttle valve (9); wherein the cold side outlet of the water-carbon dioxide heat exchanger (4) is communicated with the cold side of the heat regenerator (5) and the compressor (6) in sequence; the outlet of the compressor (6) is communicated with the hot side of the carbon dioxide-particle/molten salt heat exchanger (8), the hot side of the heat regenerator (5) and the throttle valve (9) in sequence; and finally, the outlet of the throttle valve (9) is communicated with the cold side inlet of the water-carbon dioxide heat exchanger (4) to form a closed loop.

4. The thermal power system energy storage peak shaving system for recovering latent heat in flue gas according to claim 3, characterized in that: the compressor (6) is arranged coaxially with the electric motor (7).

5. The thermal power system energy storage peak shaving system for recovering latent heat in flue gas as claimed in claim 1, wherein: the energy storage circuit comprises a cold tank (10), a pump (11), a carbon dioxide-particle/molten salt heat exchanger (8) and a hot tank (12); wherein the outlet of the cold tank (10) is communicated with the hot tank (12) through a pump (11) and the cold side of the carbon dioxide-particle/molten salt heat exchanger (8); a central heating device or a waste heat power generation device is connected between the outlet of the hot tank (12) and the cold tank (10) according to the actual demand of a user.

6. The working method of the thermal power system energy storage peak regulation system for recovering latent heat in flue gas of any one of claims 1 to 5 is characterized in that: in the flue gas cooling circuit: the water pump (3) sends cooling water to the hot side of the water-carbon dioxide heat exchanger (4), heat is transferred to carbon dioxide, then the cooled cooling water is sent to the flue gas cooler (2) to absorb low-grade waste heat in flue gas, and the heated water returns to the inlet of the water pump (3);

in the carbon dioxide heat pump loop: after the pressure of carbon dioxide is increased by a compressor (6), the carbon dioxide is sent to the hot side of a carbon dioxide-particle/molten salt heat exchanger (8) to heat particles/molten salt, and then is sent to the hot side of a heat regenerator (5) to reduce the temperature, the carbon dioxide after temperature reduction is sent to a throttle valve (9) to reduce the pressure and enters a gas-liquid two-phase area, the carbon dioxide in a two-phase state enters the cold side of a water-carbon dioxide heat exchanger (4) to absorb low-grade heat in cooling water, and carbon dioxide saturated gas after heat absorption is heated by the heat regenerator (5) and then returns to the inlet of the compressor (6) again, so that a;

in the energy storage loop: the particles/molten salt in the cold tank (10) is sent to a carbon dioxide-particle/molten salt heat exchanger (8) by a pump (11) for heating, and the heated particles/molten salt is sent to a hot tank (12) for storage; a central heating device or a waste heat power generation device is connected between the outlet of the hot tank (12) and the cold tank (10) according to the actual demand of a user.

Technical Field

The invention belongs to the technical field of thermal power generation, and particularly relates to a thermal power system energy storage peak shaving system for recovering latent heat in flue gas and a working method.

Background

In recent years, with the rapid development of the power generation industry in China, the thermal power generating units in China have attracted attention in the aspect of waste heat utilization, such as the technologies of 'low-temperature economizer + air heater', 'bypass flue economizer + extrusion exhaust and air heating water supply' and the like, so that most of the thermal power generating units in China can directly utilize waste heat and are effectively utilized, and the efficiency of the thermal power generating units reaches the world advanced level.

However, a large amount of heat exists in the thermal power generating unit in the form of low-grade waste heat, the temperature of the part of the waste heat is usually below 50 ℃, the part of the waste heat is difficult to be directly utilized through a conventional waste heat utilization means, and most of the waste heat is dissipated to the environment through circulating cooling water and boiler exhaust smoke. But the total amount of the waste heat of the part is huge, which accounts for about 50% of the total heat of the input fuel, and the direct discharge causes serious energy waste. In order to further improve the energy efficiency of the thermal power generating unit, the recycling of low-grade waste heat is inevitable.

In addition, the emission of low-grade waste heat to the environment requires the consumption of large amounts of water resources. For example, in the process of discharging waste heat to the environment from a cooling tower, a large amount of evaporation loss is generated in the circulating cooling water, and a large amount of white mist is generated to form visual pollution; in the process of discharging the desulfurized saturated wet flue gas, white smoke plume can be generated to form visual pollution, and most of the water lost by the smoke plume comes from the water supplement of the desulfurizing tower.

If a large amount of low-grade waste heat in the thermal power generating unit is reasonably recycled, the energy efficiency of the unit is improved, and the consumption of water resources is obviously reduced. Therefore, the deep recycling of the low-grade waste heat of the thermal power generating unit has important significance.

Although a lot of researches are carried out on the aspect of low-grade waste heat utilization of a thermal power plant at present, most of the low-grade waste heat utilization of the thermal power plant adopt absorption heat pumps and the like, and the problems of small waste heat quality improvement, low COP (coefficient of performance), single use, general economy and the like exist. Therefore, a lot of original work is also required. The advantages of low temperature of the cold end, high temperature of the hot end and high COP of the carbon dioxide heat pump are combined, the low-grade waste heat in the saturated wet flue gas is firstly upgraded and recovered, and then the upgraded heat is stored through a large heat storage system, so that efficient and flexible application is realized.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide an energy storage and peak regulation system of a thermal power system for recovering latent heat in flue gas and a working method thereof. The method can effectively solve the problem that a large amount of low-grade waste heat in the saturated wet flue gas after desulfurization of the thermal power generating unit is difficult to utilize, and can recover a large amount of water resources while recovering a large amount of low-grade waste heat in the flue gas; in addition, the heat storage system can be used for carrying out auxiliary peak shaving of the thermal power generating unit according to the peak shaving requirement of the thermal power generating unit, and an electric boiler, a hot water storage tank and the like with low energy efficiency are replaced.

In order to achieve the purpose, the invention adopts the technical scheme that:

a thermal power system energy storage peak regulation system for recovering latent heat in flue gas comprises a flue gas cooling loop, a carbon dioxide heat pump loop and an energy storage loop; the flue gas cooling loop and the carbon dioxide heat pump loop exchange heat through a water-carbon dioxide heat exchanger 4; the carbon dioxide heat pump loop and the energy storage loop exchange heat through a carbon dioxide-particle/molten salt heat exchanger 8.

The flue gas cooling loop comprises a flue 1, a flue gas cooler 2, a water pump 3 and a water-carbon dioxide heat exchanger 4; wherein the flue gas cooler 2 is arranged in the flue 1 to realize the heat exchange of cooling water and flue gas; the outlet of the water pump 3 is sequentially connected with the hot side of the water-carbon dioxide heat exchanger 4 and the cold side of the flue gas cooler 2 and then connected with the inlet of the water pump 3 to form closed cooling water circulation.

The carbon dioxide heat pump loop comprises a water-carbon dioxide heat exchanger 4, a heat regenerator 5, a compressor 6, a motor 7, a carbon dioxide-particle/molten salt heat exchanger 8 and a throttle valve 9; wherein the outlet of the cold side of the water-carbon dioxide heat exchanger 4 is communicated with the cold side of the heat regenerator 5 and the compressor 6 in turn; the outlet of the compressor 6 is sequentially communicated with the hot side of the carbon dioxide-particle/molten salt heat exchanger 8, the hot side of the heat regenerator 5 and the throttle valve 9; and finally, the outlet of the throttle valve 9 is communicated with the cold side inlet of the water-carbon dioxide heat exchanger 4 to form a closed loop.

The energy storage loop comprises a cold tank 10, a pump 11, a carbon dioxide-particle/molten salt heat exchanger 8 and a hot tank 12; wherein the outlet of the cold tank 10 is communicated with the cold side of the carbon dioxide-particle/molten salt heat exchanger 8 and the hot tank 12 through a pump 11; a central heating device, a waste heat power generation device and the like can be connected between the outlet of the hot tank 12 and the cold tank 10 according to the actual requirements of users.

The compressor 6 is arranged coaxially with the motor 7.

The working method of the thermal power system energy storage peak regulation system for recovering latent heat in flue gas comprises the following steps: the water pump 3 sends cooling water to the hot side of the water-carbon dioxide heat exchanger 4, heat is transferred to carbon dioxide, then the cooled cooling water is sent to the flue gas cooler 2 to absorb low-grade waste heat in flue gas, and the heated water returns to the inlet of the water pump 3;

in the carbon dioxide heat pump loop: after the pressure of the carbon dioxide is increased by the compressor 6, the carbon dioxide is sent to the hot side of the carbon dioxide-particle/molten salt heat exchanger 8 to heat particles/molten salt, and then the carbon dioxide is sent to the hot side of the heat regenerator 5 to reduce the temperature; the cooled carbon dioxide is sent to a throttle valve 9 to be depressurized and enters a gas-liquid two-phase area, and the two-phase carbon dioxide enters the cold side of the water-carbon dioxide heat exchanger 4 to absorb low-grade heat in the cooling water; the carbon dioxide saturated gas after absorbing heat is heated by the heat regenerator 5 and then returns to the inlet of the compressor 6 again. Thus forming a compression heat pump cycle;

in the energy storage loop: the particles/molten salt in the cold tank 10 are sent to a carbon dioxide-particle/molten salt heat exchanger 8 by a pump 11 for heating, and the heated particles/molten salt is sent to a hot tank 12 for storage; a central heating device or a waste heat power generation device is connected between the outlet of the hot tank 12 and the cold tank 10 according to the actual requirement of a user.

The invention has the beneficial effects that:

when the thermal power system energy storage peak shaving system for recovering latent heat in flue gas is specifically operated, the advantages of low cold end temperature, high hot end temperature and high heating coefficient of performance (COP) of a carbon dioxide heat pump loop are combined, low-grade waste heat in saturated wet flue gas is firstly upgraded and recovered, and then upgraded heat is stored through a large heat storage system, so that efficient and flexible application is realized. The method can effectively solve the problem that a large amount of low-grade waste heat in the saturated wet flue gas after desulfurization of the thermal power generating unit is difficult to utilize, and can recover a large amount of water resources while recovering a large amount of low-grade waste heat in the flue gas; in addition, the heat storage system can be used for carrying out auxiliary peak shaving of the thermal power generating unit according to the peak shaving requirement of the thermal power generating unit, and an electric boiler, a hot water storage tank and the like with low energy efficiency are replaced.

Drawings

FIG. 1 is an overall system diagram of the present invention.

Wherein, 1 is a flue, 2 is a flue gas cooler, 3 is a water pump, 4 is a water-carbon dioxide heat exchanger, 5 is a heat regenerator, 6 is a compressor, 7 is a motor, 8 is a carbon dioxide-particle/molten salt heat exchanger, 9 is a throttle valve, 10 is a cold tank, 11 is a pump, and 12 is a hot tank.

Detailed Description

The present invention will be described in further detail with reference to examples.

As shown in fig. 1, the thermal power system energy storage peak shaving system for recovering latent heat in flue gas of the present invention includes a flue 1, a flue gas cooler 2, a water pump 3, a water-carbon dioxide heat exchanger 4, a heat regenerator 5, a compressor 6, a motor 7, a carbon dioxide-particle/molten salt heat exchanger 8, a throttle valve 9, a cold tank 10, a pump 11, and a hot tank 12.

The system comprises a flue gas cooling loop, a carbon dioxide heat pump loop and an energy storage loop. The flue gas cooling loop and the carbon dioxide heat pump loop exchange heat through a water-carbon dioxide heat exchanger 4; the carbon dioxide heat pump loop and the energy storage loop exchange heat through a carbon dioxide-particle/molten salt heat exchanger 8.

The flue gas cooling loop comprises a flue 1, a flue gas cooler 2, a water pump 3 and a water-carbon dioxide heat exchanger 4. Wherein the flue gas cooler 2 is arranged in the flue 1 to realize the heat exchange of cooling water and flue gas. The outlet of the water pump 3 is sequentially connected with the hot side of the water-carbon dioxide heat exchanger 4 and the cold side of the flue gas cooler 2 and then connected with the inlet of the water pump 3 to form closed cooling water circulation.

The carbon dioxide heat pump circuit comprises a water-carbon dioxide heat exchanger 4, a regenerator 5, a compressor 6, a motor 7, a carbon dioxide-particle/molten salt heat exchanger 8 and a throttle valve 9. Wherein the outlet of the cold side of the water-carbon dioxide heat exchanger 4 is communicated with the cold side of the heat regenerator 5 and the compressor 6 in turn. The outlet of the compressor 6 is communicated with the hot side of the carbon dioxide-particle/molten salt heat exchanger 8, the hot side of the heat regenerator 5 and the throttle valve 9 in sequence. And finally, the outlet of the throttle valve 9 is communicated with the cold side inlet of the water-carbon dioxide heat exchanger 4 to form a closed loop.

The energy storage circuit comprises a cold tank 10, a pump 11, a carbon dioxide-particle/molten salt heat exchanger 8 and a hot tank 12. Wherein the outlet of the cold tank 10 is communicated with the cold side of the carbon dioxide-particle/molten salt heat exchanger 8 and the hot tank 12 through a pump 11. A central heating device, a waste heat power generation device and the like can be connected between the outlet of the hot tank 12 and the cold tank 10 according to the actual requirements of users.

The compressor 6 is arranged coaxially with the motor 7.

The specific working process of the invention is as follows:

in the flue gas cooling circuit: the water pump 3 sends cooling water to the hot side of the water-carbon dioxide heat exchanger 4, heat is transferred to carbon dioxide, then the cooled cooling water is sent to the flue gas cooler 2 to absorb low-grade waste heat in flue gas, and the heated water returns to the inlet of the water pump 3.

In the carbon dioxide heat pump loop: after the pressure of the carbon dioxide is increased by the compressor 6, the carbon dioxide is sent to the hot side of the carbon dioxide-particle/molten salt heat exchanger 8 to heat particles/molten salt, and then the carbon dioxide is sent to the hot side of the heat regenerator 5 to reduce the temperature; the cooled carbon dioxide is sent to a throttle valve 9 to be depressurized and enters a gas-liquid two-phase area, and the two-phase carbon dioxide enters the cold side of the water-carbon dioxide heat exchanger 4 to absorb low-grade heat in the cooling water; the carbon dioxide saturated gas after absorbing heat is heated by the heat regenerator 5 and then returns to the inlet of the compressor 6 again. Thus, a compression heat pump cycle is formed.

In the energy storage loop: the particles/molten salt in the cold tank 10 is sent to the carbon dioxide-particles/molten salt heat exchanger 8 by the pump 11 to be heated, and the heated particles/molten salt is sent to the hot tank 12 to be stored. A central heating device, a waste heat power generation device and the like can be connected between the outlet of the hot tank 12 and the cold tank 10 according to the actual requirements of users.

When the specific operation is adopted, the advantages of low cold end temperature, high hot end temperature and high COP of the carbon dioxide heat pump are combined, the low-grade waste heat in the saturated wet flue gas is upgraded and recovered, and then the upgraded heat is stored through the large-scale heat storage system, so that efficient and flexible application is realized. The method can effectively solve the problem that a large amount of low-grade waste heat in the saturated wet flue gas after desulfurization of the thermal power generating unit is difficult to utilize, and can recover a large amount of water resources while recovering a large amount of low-grade waste heat in the flue gas; in addition, the heat storage system can be used for carrying out auxiliary peak shaving of the thermal power generating unit according to the peak shaving requirement of the thermal power generating unit, and an electric boiler, a hot water storage tank and the like with low energy efficiency are replaced.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.