阅读说明：本技术 一种超临界二氧化碳热电联产系统及运行方法 (Supercritical carbon dioxide cogeneration system and operation method ) 是由 刘明 杨凯旋 孙瑞强 刘继平 邢秦安 严俊杰 于 2020-11-25 设计创作，主要内容包括：本发明公开了一种超临界二氧化碳热电联产系统及运行方法,采用超临界二氧化碳循环为热电联产动力循环,耦合抽气供热系统,同时为用户提供热、电两种能源；通过热端-回热-供热过程的耦合优化,本发明可大幅度提高超临界二氧化碳动力系统的能量利用率。本发明系统针对抽气进行合理能级匹配,将供热抽气与回热系统进行耦合,减小系统中的换热不可逆损失,可以通过调整回热系统二氧化碳分流比例,满足不同的供热负荷需求,提高机组的运行灵活性；也可以使系统在满足供热温度的同时,提高进入锅炉的工质温度,降低热端换热温差,减少不可逆损失,提高机组发电效率。(The invention discloses a supercritical carbon dioxide cogeneration system and an operation method, wherein supercritical carbon dioxide circulation is adopted as cogeneration power circulation, and a gas extraction and heat supply system is coupled to provide two energy sources of heat and electricity for users; through the coupling optimization of the hot end-regenerative-heat supply process, the invention can greatly improve the energy utilization rate of the supercritical carbon dioxide power system. The system disclosed by the invention is used for reasonably matching energy levels of the extracted air, coupling the heat supply extracted air and the heat regeneration system, reducing the irreversible loss of heat exchange in the system, meeting different heat supply load requirements by adjusting the carbon dioxide flow dividing ratio of the heat regeneration system and improving the operation flexibility of the unit; the system can meet the heat supply temperature, improve the temperature of the working medium entering the boiler, reduce the temperature difference of heat exchange at the hot end, reduce the irreversible loss and improve the generating efficiency of the unit.)

1. A supercritical carbon dioxide cogeneration system characterized in that: the boiler comprises a boiler (1), wherein a working medium outlet of the boiler (1) is connected with a working medium inlet of a turbine (2), an exhaust port of the turbine (2) is sequentially connected with hot sides of a heat regenerator (31) No. 1, a heat regenerator (32) No. 2, a heat regenerator (33) No. 3 and a heat regenerator (34) No. 4, an outlet of the heat regenerator (34) No. 4 is connected with a working medium inlet of a precooler (71) No. 1, a working medium outlet of the precooler (71) No. 1 is connected with an inlet of a main compressor (4), an outlet of the main compressor (4) is sequentially connected with cold sides of the heat regenerator (34) No. 4, the heat regenerator (33) No. 2, the heat regenerator (32) No. 1 and the cold side outlet of the heat regenerator (31) No. 1 is connected;

a working medium air suction port of a turbine (2) is sequentially connected with a working medium hot side of a No. 5 heat regenerator (35), a heat supply network heater (8) and a No. 2 precooler (72), a working medium hot side outlet of the precooler (72) is connected with an inlet of a heat supply compressor (6), an outlet of the heat supply compressor (6) is connected between a cold side inlet of the No. 3 heat regenerator (33) and a cold side outlet of the No. 4 heat regenerator (34), a cold side outlet of the No. 3 heat regenerator (33) is connected with a cold side inlet of the No. 5 heat regenerator (35), and a cold side outlet of the No. 5 heat regenerator (35) is connected with an;

the cooling water inlet and outlet of the heating network heater (8) are connected with the heating network, and the cooling water inlet and outlet of the No. 1 precooler (71) and the No. 2 precooler (72) are connected with the cooling water system.

2. The supercritical carbon dioxide cogeneration system of claim 1, wherein: the outlet of the No. 4 heat regenerator (34) is also connected with the working medium inlet of the recompressor (5), and the working medium outlet of the recompressor (5) is connected with the cold side inlet of the No. 1 heat regenerator (31).

3. The supercritical carbon dioxide cogeneration system of claim 1, wherein: the pressure of the exhaust port of the turbine (2) is 7.7MPa-8.5 MPa.

4. The supercritical carbon dioxide cogeneration system of claim 1, wherein: the pressure of the air extraction opening of the turbine (2) is 10MPa-15.0 MPa.

5. The supercritical carbon dioxide cogeneration system of claim 1, wherein: the temperature of working medium outlets of the precoolers No. 1 (71) and No. 2 (72) is 33-38 ℃.

6. The supercritical carbon dioxide cogeneration system of claim 1, wherein: the deviation between the outlet temperature of the heat supply compressor (6) and the outlet temperature of the No. 4 heat regenerator (34) is less than 5 ℃.

7. The supercritical carbon dioxide cogeneration system of claim 1, wherein: the temperature of the working medium hot side inlet of the No. 2 precooler (72) is 45-75 ℃.

8. A method of operating a supercritical carbon dioxide cogeneration system according to any one of claims 1 to 7, characterized by: after the supercritical carbon dioxide is boosted in a main compressor (4), the supercritical carbon dioxide is sequentially absorbed in a No. 4 heat regenerator (34), a No. 3 heat regenerator (33), a No. 2 heat regenerator (32), a No. 1 heat regenerator (31) and a boiler (1) to become high-temperature high-pressure carbon dioxide, then the high-temperature high-pressure carbon dioxide enters a turbine (2) to do work, the exhaust gas of the turbine (2) is sequentially released in the No. 1 heat regenerator (31), the No. 2 heat regenerator (32), the No. 3 heat regenerator (33) and the No. 4 heat regenerator (34) to be divided into two strands, one strand is boosted by a recompressor (5) and then gathered into an inlet of the No. 1 heat regenerator (31), and the other strand is cooled in a precooler (7) and then enters the main compressor (;

after high-temperature and high-pressure carbon dioxide enters the turbine (2) to do work, part of the high-temperature and high-pressure carbon dioxide is extracted from an air extraction opening of the turbine (2), and after heat is released in the No. 5 heat regenerator (35), the No. 2 heat regenerator (8) and the No. 2 precooler (72) in sequence, the high-temperature and high-pressure carbon dioxide is boosted by the heat supply compressor (6) and then flows into a cold working medium inlet of the No. 3 heat regenerator (;

a part of working medium of the cold side outlet shunt part of the heat regenerator (33) No. 3 is heated by the heat regenerator (35) No. 5 and then is converged into the cold side working medium outlet of the heat regenerator (31) No. 1, and the temperature of the supercritical carbon dioxide working medium entering the heat supply network heater (8) is adjusted by adjusting the air extraction proportion of the part of working medium, so that different heat supply load requirements are met, and the operation flexibility of the unit is improved.

Technical Field

The invention belongs to the field of cogeneration, and particularly relates to a supercritical carbon dioxide cogeneration system and an operation method.

Background

The stable growth of the economy of China is not supported by a strong energy system. Fossil energy structures in China are unbalanced, coal is the main body of primary energy consumption in China, and short-time internal combustion coal power generation is still the main power generation mode in China. The thermal power generating unit is used as a large coal consumer in China, and the annual coal consumption accounts for 50% of the total coal consumption in China.

The thermal power technology progress of China is changed from the ways of improving initial parameters, reheating steam and the like to the directions of full-working-condition operation, deep utilization of waste heat and the like. Meanwhile, the northern area develops centralized heat supply, reduces the emission of pollutants of small heat supply boilers, and improves the environmental problem of frequent haze in the northern area in winter. Therefore, the cogeneration of heat and power of the thermal power generating unit has important significance for the energy conservation and emission reduction work in China.

The supercritical carbon dioxide power cycle has the advantages of large energy density, compact system structure, high cycle efficiency, realization based on the existing materials, smaller system component size, compact structure and the like. Thus, supercritical carbon dioxide power cycles are expected to replace steam power cycles.

At present, high back pressure heat supply or steam turbine air extraction heat supply is mostly adopted by a cogeneration unit in northern areas of China, but in a supercritical carbon dioxide system, turbine exhaust steam pressure is mostly below 10MPa, when the working medium temperature is higher than 60 ℃, heat release is slow, when the working medium temperature is lower than 60 ℃, a heat release curve is difficult to match, large irreversible loss is easy to generate, the residual heat required by heat supply is mostly 50-140 ℃, the difficulty in exhaust steam utilization in the temperature range is large, so that the supercritical carbon dioxide coal-fired power generation system is different from a traditional high back pressure heat supply unit in heat supply, energy levels are reasonably matched, and the requirements on heat supply temperature and load are the problems required to be solved by supercritical carbon dioxide power circulation.

Disclosure of Invention

In order to overcome the problems in the prior art, the invention aims to provide a supercritical carbon dioxide cogeneration system and an operation method thereof. Through the coupling optimization of the hot end-regenerative-heat supply process, the invention can greatly improve the energy utilization rate of the supercritical carbon dioxide power system.

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

a supercritical carbon dioxide cogeneration system comprises a boiler 1, wherein a working medium outlet of the boiler 1 is connected with a working medium inlet of a turbine 2, an exhaust port of the turbine 2 is sequentially connected with hot sides of a heat regenerator 31 No. 1, a heat regenerator 32 No. 2, a heat regenerator 33 No. 3 and a heat regenerator 34 No. 4, an outlet of the heat regenerator 34 No. 4 is connected with a working medium inlet of a precooler 71 No. 1, a working medium outlet of the precooler 71 No. 1 is connected with an inlet of a main compressor 4, an outlet of the main compressor 4 is sequentially connected with cold sides of the heat regenerator 34 No. 4, the heat regenerator 33 No. 3, the heat regenerator 32 No. 2 and the heat regenerator 31 No. 1, and a cold side outlet of the heat regenerator 31;

the extraction opening of a working medium of a turbine 2 is sequentially connected with the working medium hot side of a No. 5 heat regenerator 35, a heating network heater 8 and a No. 2 precooler 72, the outlet of the working medium hot side of the precooler 72 is connected with the inlet of a heat supply compressor 6, the outlet of the heat supply compressor 6 is connected between the cold side inlet of the No. 3 heat regenerator 33 and the cold side outlet of the No. 4 heat regenerator 34, the cold side outlet of the No. 3 heat regenerator 33 is connected with the cold side inlet of the No. 5 heat regenerator 35, and the cold side outlet of the No. 5;

the cooling water inlet and outlet of the heating network heater 8 are connected with the heating network, and the cooling water inlet and outlet of the No. 1 precooler 71 and the No. 2 precooler 72 are connected with the cooling water system.

The outlet of the No. 4 heat regenerator 34 is also connected with the working medium inlet of the recompressor 5, and the working medium outlet of the recompressor 5 is connected with the cold side inlet of the No. 1 heat regenerator 31.

The pressure of the exhaust port of the turbine 2 is 7.7MPa-8.5 MPa.

The pressure of the air extraction opening of the turbine 2 is 10MPa-15.0 MPa.

The working medium outlet temperature of precooler 71 No. 1 and precooler 72 No. 2 is 33-38 ℃.

The deviation between the outlet temperature of the heat supply compressor 6 and the outlet temperature of the No. 4 heat regenerator 34 is less than 5 ℃.

The inlet temperature of the hot side of the working medium of the No. 2 precooler 72 is 45-75 ℃.

The operation method of the supercritical carbon dioxide cogeneration system comprises the steps that after the supercritical carbon dioxide is boosted in a main compressor 4, the supercritical carbon dioxide is sequentially absorbed in a heat regenerator 34 No. 4, a heat regenerator 33 No. 3, a heat regenerator 32 No. 2, a heat regenerator 31 No. 1 and a boiler 1 to become high-temperature high-pressure carbon dioxide, then the high-temperature high-pressure carbon dioxide enters a turbine 2 to do work, exhaust gas of the turbine 2 is sequentially released in the heat regenerator 31 No. 1, the heat regenerator 32 No. 2, the heat regenerator 33 No. 3 and the heat regenerator 34 No. 4 to be divided into two parts, one part of the exhaust gas is boosted by a re-compressor 5 and then enters an inlet of the heat regenerator 31 No. 1, and the other part of the exhaust gas enters the main compressor 1 after being cooled;

after high-temperature and high-pressure carbon dioxide enters the turbine 2 to do work, part of the high-temperature and high-pressure carbon dioxide is extracted from an air extraction opening of the turbine 2, and after heat is released in the No. 5 heat regenerator 35, the heat supply network heat regenerator 8 and the No. 2 precooler 72 in sequence, the high-temperature and high-pressure carbon dioxide is boosted by the heat supply compressor 6 and then flows into a cold working medium inlet of the No. 3 heat regenerator;

a part of working medium of the cold side outlet shunt of the No. 3 heat regenerator 33 is heated by the No. 5 heat regenerator 35 and then flows into the cold side working medium outlet of the No. 1 heat regenerator 31, and the temperature of the supercritical carbon dioxide working medium entering the heat supply network heater 8 is adjusted by adjusting the air extraction proportion of the part, so that different heat supply load requirements are met, and the operation flexibility of the unit is improved.

Compared with the prior art, the invention has the following advantages:

(1) the invention adopts the supercritical carbon dioxide cycle as the cogeneration power cycle, couples an air pumping and heat supplying system, simultaneously provides two energy sources of heat and electricity for users, and can greatly improve the energy utilization rate of the supercritical carbon dioxide power system through the coupling optimization of the hot end-heat regeneration-heat supplying process;

(2) the invention adopts multi-stage regenerative flow division and recompression supercritical carbon dioxide power cycle, and the system has higher cycle efficiency;

(3) the invention can meet different heat supply load requirements by adjusting the carbon dioxide split-flow ratio of the regenerative system, thereby improving the operation flexibility of the unit;

(4) the invention can improve the temperature of the working medium entering the boiler, reduce the temperature difference of heat exchange at the hot end, reduce the irreversible loss and improve the generating efficiency of the unit while meeting the heat supply temperature of the system.

Drawings

Figure 1 is a graph of enthalpy versus temperature for different pressures of carbon dioxide.

Fig. 2 is a schematic view of a supercritical carbon dioxide cogeneration system of the present invention.

FIG. 3 is a graph showing the temperature-enthalpy change trend of the working medium during heat exchange.

In the figure: the system comprises a boiler 1, a turbine 2, a heat regenerator 31 No. 1, a heat regenerator 32 No. 2, a heat regenerator 33 No. 3, a heat regenerator 34 No. 4, a heat regenerator 35 No. 5, a main compressor 4, a recompressor 5, a heat supply compressor 6, a precooler 71 No. 1, a precooler 72 No. 2 and a heat supply network heater 8.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Principle of operation

The enthalpy value and temperature change curve of the carbon dioxide working medium under different pressures is shown in figure 1, in the supercritical carbon dioxide system, the turbine exhaust steam pressure is mostly below 10MPa, when the working medium temperature is higher than 60 ℃, the heat release is slow, when the working medium temperature is lower than 60 ℃, the heat release curve is difficult to match, large irreversible loss is easy to generate, the residual heat required by heat supply is mostly 50-140 ℃, the exhaust steam utilization difficulty in the temperature range is large, and therefore the heat supply difference of the supercritical carbon dioxide coal-fired power generation system is different from that of a traditional high-back-pressure heat supply unit. When the pressure of the carbon dioxide is high, the heat release curve is good in linearity and easy to match, so that the mode that high-pressure working medium heat supply is obtained through turbine air extraction is relatively reasonable and the system is simple. The turbine exhaust temperature of the supercritical carbon dioxide system is high, so the problem of gradient utilization of exhaust heat is solved by the exhaust heat supply.

As shown in fig. 2, the supercritical carbon dioxide cogeneration system of the present invention comprises a boiler 1, wherein a working medium outlet of the boiler 1 is connected with a working medium inlet of a turbine 2, an exhaust port of the turbine 2 is connected with hot sides of a heat regenerator 31 No. 1, a heat regenerator 32 No. 2, a heat regenerator 33 No. 3 and a heat regenerator 34 No. 4 in sequence, an outlet of the heat regenerator 34 No. 4 is connected with a working medium inlet of a precooler 71 No. 1, a working medium outlet of the precooler 71 No. 1 is connected with an inlet of a main compressor 4, an outlet of the main compressor 4 is connected with cold sides of the heat regenerator 34 No. 4, the heat regenerator 33 No. 3, the heat regenerator 32 No. 2 and the heat regenerator 31 No. 1 in sequence, and a cold side; the extraction opening of a working medium of a turbine 2 is sequentially connected with the working medium hot side of a No. 5 heat regenerator 35, a heating network heater 8 and a No. 2 precooler 72, the outlet of the working medium hot side of the precooler 72 is connected with the inlet of a heat supply compressor 6, the outlet of the heat supply compressor 6 is connected between the cold side inlet of the No. 3 heat regenerator 33 and the cold side outlet of the No. 4 heat regenerator 34, the cold side outlet of the No. 3 heat regenerator 33 is connected with the cold side inlet of the No. 5 heat regenerator 35, and the cold side outlet of the No. 5; the cooling water inlet and outlet of the heating network heater 8 are connected with the heating network, and the cooling water inlet and outlet of the No. 1 precooler 71 and the No. 2 precooler 72 are connected with the cooling water system.

As a preferred embodiment of the invention, the outlet of the No. 4 heat regenerator 34 is also connected with the working medium inlet of the recompressor 5, the working medium outlet of the recompressor 5 is connected with the cold side inlet of the No. 1 heat regenerator 31, and the system circulation efficiency is higher by adopting a shunting recompression mode.

As a preferred embodiment of the invention, the pressure at the exhaust port of the turbine 2 is 7.7MPa-8.5MPa, so that the higher output power of the turbine 2 can be maintained, and the supercritical state of the carbon dioxide working medium in the whole cycle can be ensured.

As a preferred embodiment of the present invention, the pressure of the exhaust port of the turbine 2 is 10MPa to 15.0MPa, so that the pressure required by the heat supply network heater 8 can be satisfied.

As a preferred embodiment of the invention, the temperature of working medium outlets of precoolers 71 and 72 of precoolers 1 and 2 is 33-38 ℃, so that the average heat release temperature of the circulation is lower, and the higher circulation efficiency of the system is ensured.

As a preferred embodiment of the invention, the deviation between the outlet temperature of the heat supply compressor 6 and the outlet temperature of the No. 4 regenerator 34 is less than 5 ℃, so that the irreversible loss caused by the convergence of two working mediums can be reduced.

The temperature of the hot side inlet of the working medium of the No. 2 precooler 72 is 45-75 ℃, so that the reasonable heat exchange end difference of the cold end of the heating network heater 8 can be ensured.

The invention relates to an operation method of a supercritical carbon dioxide cogeneration system, after the supercritical carbon dioxide is boosted in a main compressor 4, the supercritical carbon dioxide is sequentially absorbed in a heat regenerator 34 No. 4, a heat regenerator 33 No. 3, a heat regenerator 32 No. 2, a heat regenerator 31 No. 1 and a boiler 1 to become high-temperature high-pressure carbon dioxide, then the high-temperature high-pressure carbon dioxide enters a turbine 2 to do work, the exhaust gas of the turbine 2 is sequentially released in the heat regenerator 31 No. 1, the heat regenerator 32 No. 2, the heat regenerator 33 No. 3 and the heat regenerator 34 No. 4 to be divided into two strands, one strand is boosted by a recompressor 5 and then merged into an inlet of the heat regenerator 31 No. 1, and the other strand is cooled in a precooler 7 and then enters the main compressor 1 to;

after high-temperature and high-pressure carbon dioxide enters the turbine 2 to do work, part of the high-temperature and high-pressure carbon dioxide is extracted from an air extraction opening of the turbine 2, and after heat is released in the No. 5 heat regenerator 35, the heat supply network heat regenerator 8 and the No. 2 precooler 72 in sequence, the high-temperature and high-pressure carbon dioxide is boosted by the heat supply compressor 6 and then flows into a cold working medium inlet of the No. 3 heat regenerator;

a part of working medium of the cold side outlet shunt of the No. 3 heat regenerator 33 is heated by the No. 5 heat regenerator 35 and then flows into the cold side working medium outlet of the No. 1 heat regenerator 31, and the temperature of the supercritical carbon dioxide working medium entering the heat supply network heater 8 is adjusted by adjusting the air extraction proportion of the part, so that different heat supply load requirements are met, and the operation flexibility of the unit is improved.

The invention discloses a supercritical carbon dioxide cogeneration system and an operation method thereof. Through the coupling optimization of the hot end-regenerative-heat supply process, the invention can greatly improve the energy utilization rate of the supercritical carbon dioxide power system. Because the temperature of the supercritical carbon dioxide is changed in the heat release process when the pressure is lower, and reasonable temperature matching is difficult to perform in the low-temperature section, the heat supply of the supercritical carbon dioxide coal-fired power generation system is obviously different from that of the traditional high-back-pressure heat supply unit, and the heat supply of the working medium with higher pressure obtained by turbine extraction is a relatively reasonable and simple mode. The temperature-enthalpy change trend curve of the working medium in the heat exchange process of the heat exchanger is shown in figure 3, the system carries out reasonable energy level matching aiming at air extraction, couples heat supply air extraction and a heat regeneration system, reduces the irreversible loss of heat exchange in the system, can meet different heat supply load requirements by adjusting the carbon dioxide shunt ratio of the heat regeneration system, and improves the operation flexibility of a unit; the system can meet the heat supply temperature, improve the temperature of the working medium entering the boiler, reduce the temperature difference of heat exchange at the hot end, reduce the irreversible loss and improve the generating efficiency of the unit.