阅读说明：本技术 一种供工业蒸汽超临界二氧化碳动力系统及运行方法 (Power system for industrial steam supercritical carbon dioxide 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：本发明公开了一种供工业蒸汽超临界二氧化碳动力系统及运行方法,本发明采用超临界二氧化碳循环为动力循环,耦合蒸汽发生系统,同时为用户提供蒸汽、电两种能源；通过热端-回热-蒸汽发生过程的耦合优化,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；本发明系统将蒸汽发生过程分为两个阶段：先通过中温回热器出口热侧工质抽气初次加热给水,然后利用分流的低温烟气二次加热工业蒸汽,合理利用系统低温余热,还可以通过调整二氧化碳抽气和烟气分流比例,调节供蒸汽的温度,满足不同工业抽汽负荷需求,提高机组运行灵活性。(The invention discloses a supercritical carbon dioxide power system for industrial steam and an operation method thereof, wherein supercritical carbon dioxide circulation is adopted as power circulation and coupled with a steam generation system, and two energy sources of steam and electricity are provided for users at the same time; through the coupling optimization of the hot end-regenerative-steam generation process, the energy utilization rate of the supercritical carbon dioxide power system can be greatly improved; the system of the invention divides the steam generation process into two stages: the hot side working medium at the outlet of the medium-temperature heat regenerator is firstly used for pumping air and primarily heating water supply, then the split low-temperature flue gas is used for secondarily heating industrial steam, the low-temperature waste heat of the system is reasonably utilized, the temperature of the steam supply can be adjusted by adjusting the proportion of carbon dioxide pumping air and flue gas splitting, the requirements of different industrial steam pumping loads are met, and the operation flexibility of the unit is improved.)

1. A power system for industrial steam supercritical carbon dioxide is characterized in that: the system comprises a boiler (1), wherein a working medium outlet of a supercritical carbon dioxide high-temperature heating surface (11) in 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 high-temperature heat regenerator (3), a medium-temperature heat regenerator (4) and a low-temperature heat regenerator (5), a hot side outlet of the low-temperature heat regenerator (5) is connected with a working medium inlet of a precooler (6), a working medium outlet of the precooler (6) is connected with an inlet of a main compressor (7), an outlet of the main compressor (7) is sequentially connected with a low-temperature heat regenerator (5), a medium-temperature heat regenerator (4) and a cold side of the high-temperature heat regenerator (3), and a cold side outlet of the high-temperature heat regenerator (3) is;

the hot side outlet of the medium temperature heat regenerator (4) is also connected with the hot side inlet of the feed water heater (9), the hot side outlet of the feed water heater (9) is connected with the hot side outlet of the low temperature heat regenerator (5), the cold side inlet of the feed water heater (9) is connected with the water supply port, the cold side outlet of the feed water heater (9) is connected with the inlet of the feed water heating surface (13) of the boiler (1), and the outlet of the feed water heating surface (13) is connected with the steam supply port.

2. The industrial steam supercritical carbon dioxide power system according to claim 1, characterized in that: the hot side outlet of the low-temperature heat regenerator (5) is also connected with the working medium inlet of the recompressor (8), and the working medium outlet of the recompressor (8) is connected with the cold side inlet of the high-temperature heat regenerator (3).

3. The industrial steam supercritical carbon dioxide power system according to claim 2, characterized in that: the temperature of the working medium outlet of the secondary compressor (8) is 180-220 ℃.

4. The industrial steam supercritical carbon dioxide power system according to claim 1, characterized in that: the water feeding heating surface (13) in the boiler (1) is arranged in a section with the smoke temperature lower than 400 ℃.

5. The industrial steam supercritical carbon dioxide power system according to claim 1, characterized in that: the supercritical carbon dioxide high-temperature heating surface (11) in the boiler (1) is arranged in a section with the flue gas temperature higher than 400 ℃.

6. The industrial steam supercritical carbon dioxide power system according to claim 1, characterized in that: an air preheater (12) is also arranged in the boiler (1), and the air preheater (12) is arranged in a section with the smoke temperature lower than 400 ℃.

7. The industrial steam supercritical carbon dioxide power system according to claim 1, characterized in that: the pressure of the exhaust port of the turbine (2) is 7.7MPa-8.5 MPa.

8. The industrial steam supercritical carbon dioxide power system according to claim 1, characterized in that: the working medium outlet temperature of the precooler (6) is 33-38 ℃.

9. The industrial steam supercritical carbon dioxide power system according to claim 1, characterized in that: the water supply temperature at the outlet of the water supply heater (9) is 110-130 ℃.

10. The method of operating an industrial steam supercritical carbon dioxide power system according to any one of claims 1 to 9, characterized by: after the pressure of supercritical carbon dioxide is increased in a main compressor (7), the supercritical carbon dioxide is sequentially absorbed in a low-temperature heat regenerator (5), a medium-temperature heat regenerator (4), a high-temperature heat regenerator (3) and a supercritical carbon dioxide high-temperature heating surface (11) to form high-temperature high-pressure carbon dioxide, then the high-temperature high-pressure carbon dioxide enters a turbine (2) to do work, exhaust of the turbine (2) is sequentially released in the high-temperature heat regenerator (3), the medium-temperature heat regenerator (4) and the low-temperature heat regenerator (5) to be divided into two strands, one strand is increased in pressure by a re-compressor (8) and then converged into an inlet of the high-temperature heat regenerator (3), and the other strand enters the main compressor (7) after being cooled;

part of working medium which is shunted at the hot side outlet of the medium temperature heat regenerator (4) is cooled by the feed water heater (9) and then converges into the hot side outlet of the low temperature heat regenerator (5), and the temperature of the feed water at the outlet of the feed water heater (9) is adjusted by adjusting the air extraction proportion of the part of supercritical carbon dioxide working medium, so that the requirements of different industrial steam extraction loads are met, and the operation flexibility of the unit is improved;

the feed water is heated by the feed water heater (9) and the feed water heating surface (13) in the boiler (1) to generate steam to meet the industrial steam requirement, and the temperature of the heat supply steam is adjusted by adjusting the flow of the flue gas which is distributed to the air preheater (12) and the feed water heating surface (13) in the boiler (1), so that different industrial steam extraction load requirements are met, and the operation flexibility of the unit is improved.

Technical Field

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

Background

The stable growth of the economy of China is not supported by a strong energy system. The realization of cogeneration and the simultaneous satisfaction of the electricity and heat load requirements of the society are one of the main directions of the development of the future power generation system. Meanwhile, the cogeneration is one of the most effective means for saving energy, reducing emission and improving the energy utilization efficiency of the power station. In recent years, the energy of China is developing towards diversification, but the number of thermal power is large, the technology is mature, and the short-time internal combustion coal power generation is still the main power generation mode of China. The coal consumption of the thermal power generating unit accounts for about 50% of the total coal consumption of the whole country.

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, and the cogeneration enters a rapid development period. The supercritical carbon dioxide power cycle has the advantages of high energy density, compact system structure, high cycle efficiency and the like, and is a main power cycle form in the future instead of water-based industrial Rankine cycle. Therefore, the method has wide development prospect for realizing cogeneration based on supercritical carbon dioxide power circulation and has important significance for energy conservation and emission reduction work in China.

Because the exhaust steam temperature of the supercritical carbon dioxide system is more than 400 ℃, the exhaust steam heating system has large irreversible loss when used for heating industrial steam, the temperature of working medium entering a precooler is less than 100 ℃, and the requirement of industrial steam heat users is difficult to meet, proper energy level matching needs to be carried out on the system, and a reasonable heat source is found for supplying the industrial steam.

Disclosure of Invention

In order to overcome the problems in the prior art, the invention aims to provide a supercritical carbon dioxide power system for industrial steam and an operation method thereof. Through the coupling optimization of the hot end-regenerative-steam generation 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 power system for supplying industrial steam with supercritical carbon dioxide comprises a boiler 1, wherein a working medium outlet of a supercritical carbon dioxide high-temperature heating surface 11 in 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 a high-temperature heat regenerator 3, a medium-temperature heat regenerator 4 and a hot side of a low-temperature heat regenerator 5, a hot side outlet of the low-temperature heat regenerator 5 is connected with a working medium inlet of a precooler 6, a working medium outlet of the precooler 6 is connected with an inlet of a main compressor 7, an outlet of the main compressor 7 is sequentially connected with a low-temperature heat regenerator 5, the medium-temperature heat regenerator 4 and a cold side of the high-temperature heat regenerator 3, and a cold side outlet of the high;

the hot side outlet of the medium temperature heat regenerator 4 is also connected with the hot side inlet of the feed water heater 9, the hot side outlet of the feed water heater 9 is connected with the hot side outlet of the low temperature heat regenerator 5, the cold side inlet of the feed water heater 9 is connected with the water supply inlet, the cold side outlet of the feed water heater 9 is connected with the inlet of the feed water heating surface 13 of the boiler 1, and the outlet of the feed water heating surface 13 is connected with the steam supply interface.

The hot side outlet of the low-temperature heat regenerator 5 is also connected with the working medium inlet of the recompressor 8, and the working medium outlet of the recompressor 8 is connected with the cold side inlet of the high-temperature heat regenerator 3.

The temperature of the working medium outlet of the secondary compressor 8 is 180-220 ℃.

The feedwater heating surface 13 in the boiler 1 is arranged in a section where the flue gas temperature is below 400 ℃.

The supercritical carbon dioxide high-temperature heating surface 11 in the boiler 1 is arranged in a section with the flue gas temperature higher than 400 ℃.

An air preheater 12 is also arranged in the boiler 1, the air preheater 12 being arranged in a section where the flue gas temperature is below 400 ℃.

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

The temperature of the working medium outlet of the precooler 6 is 33-38 ℃.

The water supply temperature at the outlet of the water supply heater 9 is 110-130 ℃.

The operation method of the industrial steam supercritical carbon dioxide power system is characterized by comprising the following steps: after the pressure of supercritical carbon dioxide is increased in the main compressor 7, the supercritical carbon dioxide absorbs heat in the low-temperature heat regenerator 5, the medium-temperature heat regenerator 4, the high-temperature heat regenerator 3 and the supercritical carbon dioxide high-temperature heating surface 11 in sequence to form high-temperature high-pressure carbon dioxide, then the high-temperature high-pressure carbon dioxide enters the turbine 2 to do work, the exhaust gas of the turbine 2 is released heat in the high-temperature heat regenerator 3, the medium-temperature heat regenerator 4 and the low-temperature heat regenerator 5 in sequence and then divided into two parts, one part is increased in pressure by the recompressor 8 and then converged into the inlet of the high-temperature heat regenerator 3, and the other part is cooled;

part of working medium which is shunted at the hot side outlet of the medium temperature heat regenerator 4 is cooled by the water supply heater 9 and then is gathered at the hot side outlet of the low temperature heat regenerator 5, and the temperature of water supplied at the outlet of the water supply heater 9 is adjusted by adjusting the air extraction proportion of the part of supercritical carbon dioxide working medium, so that the requirements of different industrial steam extraction loads are met, and the operation flexibility of a unit is improved;

the feed water is heated by the feed water heater 9 and the feed water heating surface 13 in the boiler 1 to generate steam to meet the industrial steam requirement, the temperature of the heat supply steam is adjusted by adjusting the flow of the flue gas which is distributed to the air preheater 12 and the feed water heating surface 13 in the boiler 1, different industrial steam extraction 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 the steam generation system, provides two energy sources of steam 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-steam generation 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 divides the steam generation process into two stages: firstly, the hot side working medium at the outlet of the medium temperature heat regenerator is used for pumping air to heat the supplied water for the first time, and then the split low-temperature flue gas is used for heating the industrial steam for the second time, so that the low-temperature waste heat of the system is reasonably utilized, and the pinch point of a water supply heater is also avoided;

(4) the invention can adjust the temperature of steam supply by adjusting the proportion of carbon dioxide extraction and flue gas diversion, meet the requirements of different industrial steam extraction loads and improve the operation flexibility of the unit.

Drawings

FIG. 1 is a schematic diagram of a power system for industrial steam supercritical carbon dioxide in accordance with the present invention.

Figure 2 is a plot of enthalpy versus temperature for carbon dioxide and water.

In the figure: the system comprises a boiler 1, a turbine 2, a high-temperature regenerator 3, a medium-temperature regenerator 4, a low-temperature regenerator 5, a precooler 6, a main compressor 7, a recompressor 8, a feed water heater 9, a supercritical carbon dioxide high-temperature heating surface 11, an air preheater 12 and a feed water heating surface 13.

Detailed Description

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

Principle of operation

The invention discloses a power system for industrial steam supercritical carbon dioxide and an operation method. The invention adopts supercritical carbon dioxide circulation as cogeneration power circulation, couples a steam generation system and provides two energy sources of steam and electricity for users. Through the coupling optimization of the hot end-regenerative-steam generation process, the invention can greatly improve the energy utilization rate of the supercritical carbon dioxide power system. Because the steam generation process has phase change heat exchange, the problem of pinch point can occur when only carbon dioxide is used for heating the feed water heater, and the enthalpy value-temperature change curve of carbon dioxide and water is shown in figure 1, which can be seen from the figure: if the pressure of water is 1MPa and the pressure of the carbon dioxide working medium is 8MPa, the heat exchanger can generate a pinch point at about 179 ℃ only by adopting the carbon dioxide as a heat source to heat the water working medium, and the heat exchange of the heat exchanger is seriously deteriorated. The pressure of the water working medium and the carbon dioxide is changed, the temperature of the pinch point is also changed, and if only the carbon dioxide is used as a heat source in the steam generation process, the pinch point problem is difficult to avoid.

To avoid pinch points in the feedwater heater, the present system divides the steam generation process into two stages: the hot side working medium at the outlet of the medium-temperature heat regenerator is firstly used for pumping air and primarily heating water supply, then the split low-temperature flue gas is used for secondarily heating industrial steam, the low-temperature waste heat of the system is reasonably utilized, the temperature of the steam supply can be adjusted by adjusting the proportion of carbon dioxide pumping air and flue gas splitting, the requirements of different industrial steam pumping loads are met, and the operation flexibility of the unit is improved.

As shown in figure 2, the power system for supplying industrial steam with supercritical carbon dioxide comprises a boiler 1, wherein a working medium outlet of a high-temperature heating surface 11 of the supercritical carbon dioxide in 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 a high-temperature heat regenerator 3, an intermediate-temperature heat regenerator 4 and a hot side of a low-temperature heat regenerator 5, a hot side outlet of the low-temperature heat regenerator 5 is connected with a working medium inlet of a precooler 6, a working medium outlet of the precooler 6 is connected with an inlet of a main compressor 7, an outlet of the main compressor 7 is sequentially connected with a low-temperature heat regenerator 5, the intermediate-temperature heat regenerator 4 and a cold side of the high-temperature heat regenerator 3, and a cold side outlet of the; the hot side outlet of the medium temperature heat regenerator 4 is also connected with the hot side inlet of the feed water heater 9, the hot side outlet of the feed water heater 9 is connected with the hot side outlet of the low temperature heat regenerator 5, the cold side inlet of the feed water heater 9 is connected with the water supply inlet, the cold side outlet of the feed water heater 9 is connected with the inlet of the feed water heating surface 13 of the boiler 1, and the outlet of the feed water heating surface 13 is connected with the steam supply interface.

As a preferred embodiment of the invention, the hot side outlet of the low-temperature heat regenerator 5 is also connected with the working medium inlet of the recompressor 8, the working medium outlet of the recompressor 8 is connected with the cold side inlet of the high-temperature heat regenerator 3, and the system circulation efficiency is higher by adopting a shunting recompression mode.

As the preferred embodiment of the invention, the temperature of the working medium outlet of the recompressor 8 is 180-220 ℃, so that the higher circulation efficiency of the system can be ensured.

As a preferred embodiment of the invention, the feed water heating surface 13 in the boiler 1 is arranged in a section with the flue gas temperature lower than 400 ℃, so that the low-temperature waste heat of the boiler 1 can be reasonably utilized, and the requirement of no industrial steam load can be met.

As a preferred embodiment of the invention, a supercritical carbon dioxide high-temperature heating surface 11 in the boiler 1 is arranged in a section with the flue gas temperature higher than 400 ℃; therefore, the average heat absorption temperature of the circulation can be improved, and the circulation efficiency is higher.

As a preferred embodiment of the present invention, an air preheater 12 is also arranged in the boiler 1, and the air preheater 12 is arranged in a section where the flue gas temperature is lower than 400 ℃, so that the heat load requirement of the air preheater 12 can be met.

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 the preferred embodiment of the invention, the temperature of the working medium outlet of the precooler 6 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 the preferred embodiment of the invention, the temperature of the feedwater at the outlet of the feedwater heater 9 is 110-130 ℃, thus avoiding the problem of heat exchange pinch in the feedwater heater 9, maintaining the temperature of the flue gas at the outlet of the feedwater heating surface 13 in a reasonable range and reducing the heat loss of the exhaust gas of the boiler 1. The invention relates to an operation method of an industrial steam supercritical carbon dioxide power system, which is characterized by comprising the following steps: after the pressure of supercritical carbon dioxide is increased in the main compressor 7, the supercritical carbon dioxide absorbs heat in the low-temperature heat regenerator 5, the medium-temperature heat regenerator 4, the high-temperature heat regenerator 3 and the supercritical carbon dioxide high-temperature heating surface 11 in sequence to form high-temperature high-pressure carbon dioxide, then the high-temperature high-pressure carbon dioxide enters the turbine 2 to do work, the exhaust gas of the turbine 2 is released heat in the high-temperature heat regenerator 3, the medium-temperature heat regenerator 4 and the low-temperature heat regenerator 5 in sequence and then divided into two parts, one part is increased in pressure by the recompressor 8 and then converged into the inlet of the high-temperature heat regenerator 3, and the other part is cooled;

part of working medium which is shunted at the hot side outlet of the medium temperature heat regenerator 4 is cooled by the water supply heater 9 and then is gathered at the hot side outlet of the low temperature heat regenerator 5, and the temperature of water supplied at the outlet of the water supply heater 9 is adjusted by adjusting the air extraction proportion of the part of supercritical carbon dioxide working medium, so that the requirements of different industrial steam extraction loads are met, and the operation flexibility of a unit is improved;

the feed water is heated by the feed water heater 9 and the feed water heating surface 13 in the boiler 1 to generate steam to meet the industrial steam requirement, the temperature of the heat supply steam is adjusted by adjusting the flow of the flue gas which is distributed to the air preheater 12 and the feed water heating surface 13 in the boiler 1, different industrial steam extraction load requirements are met, and the operation flexibility of the unit is improved.