阅读说明：本技术 辅助加热给水的超临界二氧化碳循环光热发电系统及方法 (Supercritical carbon dioxide circulating photo-thermal power generation system and method for auxiliary heating of water supply ) 是由 乔永强 张一帆 顾正萌 杨浦 张旭伟 李红智 姚明宇 于 2021-08-18 设计创作，主要内容包括：本发明公开了一种辅助加热给水的超临界二氧化碳循环光热发电系统及方法,该系统包括超临界二氧化碳循环发电系统、给水与二氧化碳换热器、熔盐储热放热系统和聚光集热系统；该系统通过聚光集热系统将太阳能转化为熔盐的热能,进而转化为超临界二氧化碳的热能,进一步将热能转化为机械能、电能。在增设的给水与二氧化碳换热器中来自超临界二氧化碳透平的高温排气加热燃煤机组的部分给水,在给水焓升保持不变的情况下,减少燃煤机组抽汽量,增加汽轮机做功,提高发电效率；通过增设给水与二氧化碳换热器,使得进入高温回热器工质温度降低,进入熔盐与二氧化碳换热器的二氧化碳温度也降低,熔盐得以有效冷却,实现了太阳能与燃煤发电的互补效果。(The invention discloses a supercritical carbon dioxide circulating photo-thermal power generation system and a supercritical carbon dioxide circulating photo-thermal power generation method for auxiliary heating of feed water, wherein the system comprises a supercritical carbon dioxide circulating power generation system, a feed water and carbon dioxide heat exchanger, a molten salt heat storage and release system and a light condensation and heat collection system; the system converts solar energy into heat energy of molten salt through the light-gathering and heat-collecting system, further converts the heat energy into heat energy of supercritical carbon dioxide, and further converts the heat energy into mechanical energy and electric energy. High-temperature exhaust gas from a supercritical carbon dioxide turbine in the added feed water and carbon dioxide heat exchanger heats part of feed water of the coal-fired unit, and under the condition that the enthalpy of the feed water is kept unchanged, the steam extraction amount of the coal-fired unit is reduced, the work of the steam turbine is increased, and the power generation efficiency is improved; by additionally arranging the water supply and carbon dioxide heat exchanger, the temperature of the working medium entering the high-temperature heat regenerator is reduced, the temperature of the carbon dioxide entering the fused salt and carbon dioxide heat exchanger is also reduced, the fused salt is effectively cooled, and the complementary effect of solar energy and coal-fired power generation is realized.)

1. A supercritical carbon dioxide circulation photo-thermal power generation system for auxiliary heating of feed water is characterized by comprising a supercritical carbon dioxide circulation power generation system, a feed water and carbon dioxide heat exchanger (11), a light-gathering heat-collecting system and a molten salt heat-storage heat-release system;

the supercritical carbon dioxide cycle power generation system comprises a molten salt and carbon dioxide heat exchanger (5), a supercritical carbon dioxide turbine (10), a high-temperature heat regenerator (12), a low-temperature heat regenerator (13), a precooler (14), a main compressor (15) and a recompressor (16);

the outlet of the supercritical carbon dioxide turbine (10) is sequentially connected with the hot side inlet and outlet of a water supply and carbon dioxide heat exchanger (11), the hot side inlet and outlet of a high-temperature regenerator (12) and the hot side inlet of a low-temperature regenerator (13), the hot side outlet of the low-temperature regenerator (13) is divided into two paths, one path is connected with the inlet of a recompressor (16), and the other path is connected with the hot side inlet of a precooler (14);

the outlet of the hot side of the precooler (14) is connected with the inlet of a main compressor (15), the outlet of the main compressor (15) is sequentially connected with the inlet and the outlet of the cold side of a low-temperature heat regenerator (13), the inlet and the outlet of the cold side of a high-temperature heat regenerator (12) and the inlet of the cold side of a fused salt and carbon dioxide heat exchanger (5), the outlet of the fused salt and the cold side of the carbon dioxide heat exchanger (5) is connected with the inlet of a supercritical carbon dioxide turbine (10), and the outlet of a compressor (16) is connected with the outlet of the cold side of the low-temperature heat regenerator (13);

the inlet at the cold side of the feed water and carbon dioxide heat exchanger (11) is connected with the outlet of the feed water pump of the coal-fired unit, and the outlet at the cold side of the feed water and carbon dioxide heat exchanger (11) is connected with the outlet at the water side of the high-pressure heater of the coal-fired unit;

the working medium of the supercritical carbon dioxide circulating power generation system is supercritical carbon dioxide;

the concentrating and heat collecting system comprises a mirror field (1) and a molten salt heat absorber (2), and the molten salt heat storage and heat release system comprises a high-temperature molten salt pump (3), a high-temperature molten salt regulating valve (4), a molten salt and carbon dioxide heat exchanger (5), a low-temperature molten salt pump (6) and a low-temperature molten salt regulating valve (7);

the fused salt heat absorber (2) absorbs sunlight reflected by the mirror field (1), an outlet of the fused salt heat absorber is connected with a hot side inlet of the fused salt and carbon dioxide heat exchanger (5) through the high-temperature fused salt pump (3) and the high-temperature fused salt adjusting valve (4) in sequence, and a hot side outlet of the fused salt and carbon dioxide heat exchanger (5) is connected with an inlet of the fused salt heat absorber (2) through the low-temperature fused salt pump (6) and the low-temperature fused salt adjusting valve (7) in sequence;

the working medium of the molten salt heat storage and release system is molten salt.

2. The supercritical carbon dioxide circulation photo-thermal power generation system for auxiliary heating of feedwater according to claim 1, characterized in that the molten salt heat storage and release system further comprises a high-temperature molten salt storage tank (8) and a low-temperature molten salt storage tank (9), wherein an inlet of the high-temperature molten salt storage tank (8) is connected with an outlet of the molten salt heat absorber (2), and an outlet of the high-temperature molten salt storage tank (8) is connected with an inlet of the high-temperature molten salt pump (3); the inlet of the low-temperature molten salt storage tank (9) is connected with the hot side outlet of the molten salt and the carbon dioxide heat exchanger (5), and the outlet of the low-temperature molten salt storage tank (9) is connected with the inlet of the low-temperature molten salt pump (6).

3. The system for supercritical carbon dioxide cycle photothermal power generation with supplemental heating of feedwater according to claim 1 wherein said mirror field (1) is comprised of a plurality of heliostats.

4. The operation method of the supercritical carbon dioxide circulating photo-thermal power generation system for auxiliary heating of water supply according to any one of claims 1 to 3 is characterized in that after being pressurized by the main compressor (15), the working medium absorbs heat in the low-temperature heat regenerator (13), the high-temperature heat regenerator (12) and the molten salt and carbon dioxide heat exchanger (5) in sequence, the working medium enters the supercritical carbon dioxide turbine (10) to expand and do work after the temperature is raised, the working medium which does work enters the water supply and carbon dioxide heat exchanger (11) to auxiliary heat the water supply of the coal-fired unit, the working medium which auxiliary heats the water supply enters the high-temperature heat regenerator (12) and the low-temperature heat regenerator (13) in sequence to release heat, the working medium after releasing heat is divided into two paths, one path of the working medium after being pressurized by the re-compressor (16) and then joins the cold side outlet of the low-temperature heat regenerator (13), the other path after being cooled by the pre-cooler (14) enters the main compressor (15) to be pressurized, completing the closed circulation of the supercritical carbon dioxide;

part of the feed water which is shunted by the feed water pump outlet of the coal-fired unit enters a feed water and carbon dioxide heat exchanger (11) to absorb heat, the temperature is raised and then the feed water is converged into a water side outlet of a high-pressure heater of the coal-fired unit or a boiler inlet, the feed water quantity flowing through the high-pressure heater is reduced, and under the condition that the enthalpy of the feed water is raised and unchanged, the steam extraction quantity of a steam turbine is correspondingly reduced, and the work of the steam turbine is increased;

the external surface of fused salt heat absorber (2) is gathered with sunlight reflection in mirror field (1), the fused salt in fused salt heat absorber (2) is heated, the fused salt after the heat absorption heaies up in fused salt heat absorber (2) is carried to fused salt and carbon dioxide heat exchanger (5) through high temperature fused salt pump (3) and high temperature fused salt governing valve (4) in proper order and is released heat, the fused salt after the heat release cooling is carried to fused salt heat absorber (2) through low temperature fused salt pump (6) and low temperature fused salt governing valve (7) in proper order and is absorbed heat once more, accomplish the fused salt circulation.

5. The operation method according to claim 4, characterized in that when the sunlight illumination condition is good, the low-temperature molten salt in the low-temperature molten salt storage tank (9) is conveyed to the molten salt heat absorber (2) to absorb heat, the high-temperature molten salt at the outlet of the molten salt heat absorber (2) is removed to enter the molten salt and carbon dioxide heat exchanger (5) to heat the carbon dioxide working medium, and the rest high-temperature molten salt enters the high-temperature molten salt storage tank (8) to be stored;

when the sunlight illumination condition is poor, the high-temperature molten salt at the outlet of the molten salt heat absorber (2) enters the molten salt and carbon dioxide heat exchanger (5), the carbon dioxide working medium cannot be heated to the required temperature, the high-temperature molten salt in the high-temperature molten salt storage tank (8) is supplemented to enter the molten salt and carbon dioxide heat exchanger (5) to heat the carbon dioxide working medium, the low-temperature molten salt after heat release is removed to enter the molten salt heat absorber (2) to absorb heat, and the residual low-temperature molten salt enters the low-temperature molten salt storage tank (9) to be stored, so that the heat release circulation of the molten salt heat storage is completed.

Technical Field

The invention relates to the technical field of multi-energy complementary power generation, in particular to a supercritical carbon dioxide circulating photo-thermal power generation system and method for auxiliary heating of water supply.

Background

With the rapid development of clean energy power generation technology and the installed scale thereof, the power supply structure in China is continuously optimized, which requires that thermal power generation mainly based on coal-fired power generation must form a power supply pattern with complementary advantages with clean energy power generation. And the complementary system of solar thermal power generation and coal-fired unit is a better choice, and can simultaneously give consideration to the requirements of energy conservation and environmental protection. At present, a solar auxiliary heating system is usually introduced into a regenerative system of a coal-fired unit of a photo-thermal and coal-fired complementary power generation system and used for heating feed water or condensed water, reducing steam extraction of a steam turbine, increasing work and further improving the power generation efficiency of the system. However, the technical scheme does not convert solar energy into electric energy or high-grade heat energy, and does not realize gradient utilization of photo-thermal resources.

In a fused salt heat storage photo-thermal power generation system with supercritical carbon dioxide circulation as power circulation, in order to pursue high circulation heat efficiency, a supercritical carbon dioxide circulation configuration with heat regeneration is generally adopted, but the temperature of a carbon dioxide working medium entering a circulation main heat exchanger is high, so that the heat obtained from a heat source in the supercritical carbon dioxide circulation is low, the carbon dioxide working medium cannot effectively cool the main heat exchanger, and the safe operation of the fused salt heat storage and heat release system is seriously influenced. Therefore, the reduction of the inlet temperature of the carbon dioxide working medium in the molten salt and the carbon dioxide main heat exchanger becomes the key of the safe and stable operation of the supercritical carbon dioxide circulating photo-thermal power generation system.

Disclosure of Invention

In order to solve the problems, the invention provides a supercritical carbon dioxide cycle photo-thermal power generation system and a supercritical carbon dioxide cycle photo-thermal power generation method for auxiliary heating of water supply, on one hand, the system utilizes high-temperature carbon dioxide after expansion and work application of a supercritical carbon dioxide turbine outlet to heat water supply in a coal-fired unit regenerative system, reduces steam extraction of a steam turbine, increases work application and further improves power generation efficiency of the coal-fired unit; on the other hand, in the conventional supercritical carbon dioxide power cycle system, high-temperature carbon dioxide at the turbine outlet directly enters a high-temperature heat regenerator for heating low-temperature carbon dioxide, and in the system disclosed by the invention, the high-temperature carbon dioxide at the supercritical carbon dioxide turbine outlet firstly exchanges heat with water supplied by a coal-fired unit, and enters the high-temperature heat regenerator for heating the low-temperature carbon dioxide after releasing heat and reducing temperature, so that the temperature of molten salt and the carbon dioxide at the cold side inlet of the carbon dioxide heat exchanger is reduced, high-temperature molten salt is effectively cooled, the molten salt heat exchanger is protected, and the operation safety of the photo-thermal power generation system is improved.

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

a supercritical carbon dioxide circulation photo-thermal power generation system for auxiliary heating of feed water comprises a supercritical carbon dioxide circulation power generation system, a feed water and carbon dioxide heat exchanger 11, a light-gathering heat collection system and a molten salt heat storage and release system;

the supercritical carbon dioxide cycle power generation system comprises a molten salt and carbon dioxide heat exchanger 5, a supercritical carbon dioxide turbine 10, a high-temperature heat regenerator 12, a low-temperature heat regenerator 13, a precooler 14, a main compressor 15 and a recompressor 16; the outlet of the supercritical carbon dioxide turbine 10 is sequentially connected with the inlet and the outlet of the hot side of a feedwater and carbon dioxide heat exchanger 11, the inlet and the outlet of the hot side of a high-temperature heat regenerator 12 and the inlet of the hot side of a low-temperature heat regenerator 13, the outlet of the hot side of the low-temperature heat regenerator 13 is divided into two paths, one path is connected with the inlet of a recompressor 16, and the other path is connected with the inlet of the hot side of a precooler 14; the outlet of the hot side of the precooler 14 is connected with the inlet of a main compressor 15, the outlet of the main compressor 15 is sequentially connected with the inlet and the outlet of the cold side of a low-temperature heat regenerator 13, the inlet and the outlet of the cold side of a high-temperature heat regenerator 12 and the inlet of the cold side of a fused salt and carbon dioxide heat exchanger 5, the outlet of the fused salt and carbon dioxide heat exchanger 5 is connected with the inlet of a supercritical carbon dioxide turbine 10, and the outlet of a recompressor 16 is connected with the outlet of the cold side of the low-temperature heat regenerator 13;

the inlet at the cold side of the feed water and carbon dioxide heat exchanger 11 is connected with the outlet of the feed water pump of the coal-fired unit, and the outlet at the cold side of the feed water and carbon dioxide heat exchanger 11 is connected with the outlet at the water side of the high-pressure heater of the coal-fired unit;

the working medium of the supercritical carbon dioxide circulating power generation system is supercritical carbon dioxide;

the concentrating and heat collecting system comprises a mirror field 1 and a molten salt heat absorber 2, and the molten salt heat storage and heat release system comprises a high-temperature molten salt pump 3, a high-temperature molten salt regulating valve 4, a molten salt and carbon dioxide heat exchanger 5, a low-temperature molten salt pump 6 and a low-temperature molten salt regulating valve 7;

the fused salt heat absorber 2 absorbs sunlight reflected by the mirror field 1, an outlet of the fused salt heat absorber 2 is connected with an inlet of a hot side of the fused salt and carbon dioxide heat exchanger 5 through a high-temperature fused salt pump 3 and a high-temperature fused salt regulating valve 4 in sequence, and an outlet of the hot side of the fused salt and carbon dioxide heat exchanger 5 is connected with an inlet of the fused salt heat absorber 2 through a low-temperature fused salt pump 6 and a low-temperature fused salt regulating valve 7 in sequence;

the working medium of the molten salt heat storage and release system is molten salt.

The molten salt heat storage and release system further comprises a high-temperature molten salt storage tank 8 and a low-temperature molten salt storage tank 9, an inlet of the high-temperature molten salt storage tank 8 is connected with an outlet of the molten salt heat absorber 2, and an outlet of the high-temperature molten salt storage tank 8 is connected with an inlet of the high-temperature molten salt pump 3; an inlet 9 of the low-temperature molten salt storage tank is connected with a hot side outlet of the molten salt and the carbon dioxide heat exchanger 5, and an outlet 9 of the low-temperature molten salt storage tank is connected with an inlet 6 of the low-temperature molten salt pump.

The heliostat field 1 is composed of a plurality of heliostats.

The operation method of the supercritical carbon dioxide circulating photo-thermal power generation system for auxiliary heating of water supply comprises the steps that after being pressurized by a main compressor 15, a working medium absorbs heat in a low-temperature heat regenerator 13, a high-temperature heat regenerator 12 and a fused salt and carbon dioxide heat exchanger 5 in sequence, the working medium enters a supercritical carbon dioxide turbine 10 to expand and do work after the temperature is raised, the working medium which does work enters a water supply and carbon dioxide heat exchanger 11 to assist in heating the water supply of a coal-fired unit, the working medium which assists in heating the water supply enters the high-temperature heat regenerator 12 and the low-temperature heat regenerator 13 in sequence to release heat, the working medium which releases heat is divided into two paths, one path of the working medium is pressurized by a re-compressor 16 and then converges to a cold side outlet of the low-temperature heat regenerator 13, the other path of the working medium is cooled by a precooler 14 and then enters the main compressor 15 to be pressurized, and the closed cycle of supercritical carbon dioxide is completed;

part of the feed water which is shunted by the feed water pump outlet of the coal-fired unit enters the feed water and carbon dioxide heat exchanger 11 to absorb heat, the temperature rises and then converges to the water side outlet of the high-pressure heater of the coal-fired unit or the boiler inlet, the feed water quantity flowing through the high-pressure heater is reduced, and under the condition that the enthalpy of the feed water is increased and unchanged, the steam extraction quantity of the steam turbine is correspondingly reduced, and the work of the steam turbine is increased;

the mirror field 1 reflects and gathers sunlight to the outer surface of the molten salt heat absorber 2 to heat the molten salt in the molten salt heat absorber 2, the molten salt heated by heat absorption in the molten salt heat absorber 2 is conveyed to the molten salt and carbon dioxide heat exchanger 5 to release heat through the high-temperature molten salt pump 3 and the high-temperature molten salt regulating valve 4 in sequence, the molten salt cooled by heat release is conveyed to the molten salt heat absorber 2 through the low-temperature molten salt pump 6 and the low-temperature molten salt regulating valve 7 in sequence to absorb heat again, and molten salt circulation is completed;

according to the operation method, when the sunlight illumination condition is good, the low-temperature molten salt in the low-temperature molten salt storage tank 9 is conveyed to the molten salt heat absorber 2 to absorb heat, the high-temperature molten salt at the outlet of the molten salt heat absorber 2 is removed to enter the molten salt and carbon dioxide heat exchanger 5 to heat a carbon dioxide working medium, and the rest high-temperature molten salt enters the high-temperature molten salt storage tank 8 to be stored;

when the sunlight illumination condition is poor, the high-temperature molten salt at the outlet of the molten salt heat absorber 2 enters the molten salt and carbon dioxide heat exchanger 5, the carbon dioxide working medium cannot be heated to the required temperature, the high-temperature molten salt in the high-temperature molten salt storage tank 8 is supplemented to enter the molten salt and carbon dioxide heat exchanger 5 to heat the carbon dioxide working medium, the released low-temperature molten salt removes the heat absorbed by the molten salt heat absorber 2, and the rest low-temperature molten salt enters the low-temperature molten salt storage tank 9 to be stored, so that the molten salt heat storage and release circulation is completed.

The invention has the following beneficial technical effects:

the system converts solar energy into heat energy of molten salt through the light-gathering and heat-collecting system, and further converts the heat energy into heat energy of supercritical carbon dioxide, pushes the supercritical carbon dioxide turbine to do work, and further converts the heat energy into mechanical energy and electric energy. By additionally arranging the feed water and carbon dioxide heat exchangers in the supercritical carbon dioxide circulation and utilizing the exhaust of the supercritical carbon dioxide turbine to heat part of feed water of the coal-fired unit, the steam extraction of the steam turbine of the coal-fired unit can be reduced and the work of the steam turbine can be increased under the condition that the enthalpy of the feed water is kept unchanged, so that the power generation efficiency of the coal-fired unit is improved; compared with the conventional system arrangement that supercritical carbon dioxide turbine exhaust directly enters the hot side of the high-temperature heat regenerator, the turbine exhaust firstly releases heat in the water supply and carbon dioxide heat exchanger, and then enters the hot side of the high-temperature heat regenerator after being cooled, so that the temperature of carbon dioxide at the outlet of the cold side of the high-temperature heat regenerator can be reduced, namely, the temperature of carbon dioxide at the inlet of the cold side of the molten salt and the carbon dioxide heat exchanger is reduced, the molten salt is effectively cooled, the safe operation of a molten salt heat storage and release system is ensured, the reliability of a photo-thermal power generation system is improved, and the complementary effect of solar energy and coal-fired power generation is realized.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention.

Wherein, 1 is a mirror field, 2 is a molten salt heat absorber, 3 is a high-temperature molten salt pump, 4 is a high-temperature molten salt regulating valve, 5 is a molten salt and carbon dioxide heat exchanger, 6 is a low-temperature molten salt pump, 7 is a low-temperature molten salt regulating valve, 8 is a high-temperature molten salt storage tank, 9 is a low-temperature molten salt storage tank, 10 is a supercritical carbon dioxide turbine, 11 is a feed water and carbon dioxide heat exchanger, 12 is a high-temperature heat regenerator, 13 is a low-temperature heat regenerator, 14 is a precooler, 15 is a main compressor, and 16 is a recompressor.

Detailed Description

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

As shown in fig. 1, the supercritical carbon dioxide cycle photo-thermal power generation system for auxiliary heating of feed water provided by the present invention includes a molten salt and carbon dioxide heat exchanger 5, a supercritical carbon dioxide turbine 10, a feed water and carbon dioxide heat exchanger 11, a high temperature regenerator 12, a low temperature regenerator 13, a precooler 14, a main compressor 15 and a recompressor 16; wherein, the outlet of the cold side of the fused salt and carbon dioxide heat exchanger 5 is connected with the inlet of the supercritical carbon dioxide turbine 10, the outlet of the supercritical carbon dioxide turbine 10 is sequentially connected with the inlet and the outlet of the hot side of the water and carbon dioxide heat exchanger 11, the inlet and the outlet of the hot side of the high-temperature heat regenerator 12 and the inlet of the hot side of the low-temperature heat regenerator 13, the outlet of the hot side of the low-temperature heat regenerator 13 is respectively connected with the inlet of the hot side of the precooler 14 and the inlet of the recompressor 16, the outlet of the hot side of the precooler 14 is connected with the inlet of the main compressor 15, the outlet of the main compressor 15 is sequentially connected with the inlet and the outlet of the cold side of the low-temperature heat regenerator 13, the inlet and the outlet of the cold side of the high-temperature heat regenerator 12 and the inlet and the cold side of the fused salt and carbon dioxide heat exchanger 5; the outlet of the recompressor 16 is connected with the outlet of the cold side of the low-temperature regenerator 13.

The supercritical carbon dioxide circulating photo-thermal power generation system for auxiliary heating of water supply further comprises a molten salt heat absorber 2, a high-temperature molten salt pump 3, a high-temperature molten salt adjusting valve 4, a molten salt and carbon dioxide heat exchanger 5, a low-temperature molten salt pump 6 and a low-temperature molten salt adjusting valve 7 which are sequentially connected; wherein, fused salt and 5 hot side entries of carbon dioxide heat exchanger are connected through high temperature fused salt pump 3 and high temperature fused salt governing valve 4 to fused salt heat absorber 2 export, and fused salt and 5 hot side exports of carbon dioxide heat exchanger are connected fused salt heat absorber 2 entries through low temperature fused salt pump 6 and low temperature fused salt governing valve 7.

The supercritical carbon dioxide circulating photo-thermal power generation system for auxiliary heating of the feed water also comprises a high-temperature molten salt storage tank 8 and a low-temperature molten salt storage tank 9; the inlet of the high-temperature molten salt storage tank 8 is connected with the outlet of the molten salt heat absorber 2, and the outlet of the high-temperature molten salt storage tank 8 is connected with the inlet of the high-temperature molten salt pump; an inlet of the low-temperature molten salt storage tank 9 is connected with an outlet of the hot side of the molten salt and the carbon dioxide heat exchanger 5, and an outlet of the low-temperature molten salt storage tank 9 is connected with an inlet of the low-temperature molten salt pump 6.

The supercritical carbon dioxide circulating photo-thermal power generation system for auxiliary heating of the feed water further comprises a feed water and carbon dioxide heat exchanger 11, wherein a cold side inlet of the feed water and carbon dioxide heat exchanger 11 is connected with a feed water pump outlet of a coal-fired unit, and a cold side outlet of the feed water and carbon dioxide heat exchanger 11 is connected with an outlet of a high-pressure heater of the coal-fired unit.

The supercritical carbon dioxide circulating photo-thermal power generation system for auxiliary heating of water supply further comprises a mirror field 1 composed of a plurality of heliostats, and sunlight reflected by the mirror field 1 is absorbed by a molten salt heat absorber 2.

In the invention, supercritical carbon dioxide is adopted as a supercritical carbon dioxide circulating working medium, and molten salt is adopted as a working medium in a heat storage and release system.

The operation method of the supercritical carbon dioxide circulating photo-thermal power generation system for auxiliary heating of the feed water provided by the invention comprises the following steps: the mirror field 1 consisting of a plurality of heliostats reflects and gathers sunlight to the outer surface of the molten salt heat absorber 2, and heats low-temperature molten salt in the molten salt heat absorber 2; the high-temperature molten salt heated by heat absorption in the molten salt heat absorber 2 is conveyed to the hot side of the molten salt and carbon dioxide heat exchanger 5 through the high-temperature molten salt pump 3 and the high-temperature molten salt regulating valve 4, and the supercritical carbon dioxide on the cold side of the molten salt and carbon dioxide heat exchanger 5 is heated; the low-temperature molten salt which releases heat and cools in the hot side of the molten salt and carbon dioxide heat exchanger 5 is conveyed to the molten salt heat absorber 2 through the low-temperature molten salt pump 6 and the low-temperature molten salt regulating valve 7, and the low-temperature molten salt absorbs heat and heats in the molten salt heat absorber 2 again to complete the molten salt heat absorption and release cycle.

When the illumination condition is good, the low-temperature molten salt stored in the low-temperature molten salt storage tank 9 is conveyed to the molten salt heat absorber 2 through the low-temperature molten salt pump 6 and the low-temperature molten salt regulating valve 7 to be heated, the high-temperature molten salt at the outlet of the molten salt heat absorber 2 enters the hot side of the molten salt and carbon dioxide heat exchanger 5, and the rest high-temperature molten salt enters the high-temperature molten salt storage tank 8 to be stored; when the illumination condition is poor or the high-temperature fused salt at the outlet of the fused salt heat absorber 2 can not heat the supercritical carbon dioxide on the cold side of the fused salt and the carbon dioxide heat exchanger to the required temperature, the high-temperature fused salt stored in the high-temperature fused salt storage tank 8 is conveyed to the hot side of the fused salt and the carbon dioxide heat exchanger 5 through the high-temperature fused salt pump 3 and the high-temperature fused salt regulating valve 4, the low-temperature fused salt at the outlet of the hot side of the fused salt and the carbon dioxide heat exchanger 5 enters the fused salt heat absorber 2, and the rest low-temperature fused salt enters the low-temperature fused salt storage tank 9 to be stored.

The molten salt and high-temperature working medium heated to the rated temperature at the cold side of the carbon dioxide heat exchanger 5 enters the supercritical carbon dioxide turbine 10 to perform expansion work, the high-temperature carbon dioxide working medium expanded to work in the supercritical carbon dioxide turbine 10 sequentially enters the water supply and carbon dioxide heat exchanger 11, the high-temperature heat regenerator 12 and the low-temperature heat regenerator 13 to release heat and cool, the carbon dioxide working medium at the outlet of the hot side of the low-temperature heat regenerator 13 is divided into two paths, one path of working medium enters the hot side of the precooler 14 to continue releasing heat and cooling, and the other path of working medium enters the recompressor 16 to pressurize.

The low-temperature carbon dioxide working medium which is discharged and cooled at the hot side of the precooler 14 is pressurized by the main compressor 15, enters the cold side of the low-temperature heat regenerator 13 to absorb heat and raise the temperature, the pressurized working medium in the recompressor 16 is converged with the working medium at the outlet of the cold side of the low-temperature heat regenerator 13, then sequentially enters the cold side of the high-temperature heat regenerator 12 and the molten salt and carbon dioxide heat exchanger 5 to continue absorbing heat and raising the temperature, and the molten salt and the high-temperature carbon dioxide at the outlet of the cold side of the carbon dioxide heat exchanger 5 enter the supercritical carbon dioxide turbine 10 again to expand and do work, so that the supercritical carbon dioxide cycle is completed.

Part of water working medium is shunted from the outlet of the water supply pump of the coal-fired unit, enters the cold side of the water supply and carbon dioxide heat exchanger 11 to absorb heat and raise temperature, and then is converged with the water supply at the outlet of the high-pressure heater of the coal-fired unit, and enters the boiler together; because part of the feed water is shunted to the feed water and carbon dioxide heat exchanger 11, the flow of the working medium entering the water side of the high-pressure heater of the coal-fired unit is reduced, under the condition that the feed water temperature entering the boiler or the feed water enthalpy of the high-pressure heater is kept unchanged, the steam extraction quantity of the steam turbine required by the high-pressure heater is correspondingly reduced, the work of the steam turbine of the coal-fired unit is increased, the power of the generator is correspondingly increased, and the power generation efficiency is improved.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments 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.