Integrated heat storage gas-steam combined cycle power generation system and operation method thereof

Abstract

The invention discloses an integrated heat storage gas-steam combined cycle power generation system and an operation method thereof. The integrated heat storage gas-steam combined cycle power generation system comprises a gas turbine power generation unit, a fused salt heat storage unit and a waste heat boiler steam power generation unit. When sunlight is sufficient, the gas turbine power generation unit is switched to a low-load operation mode, the fused salt heat storage unit heats to generate reheated steam, inlet feed water of the waste heat boiler is preheated, and the peak regulation depth of gas-steam combined cycle is increased; and when sunlight is insufficient, the fused salt heat storage unit continuously releases heat storage capacity to maintain the stability of main steam parameters and quits operation until the heat storage capacity reaches a critical threshold value, at the moment, the gas turbine power generation unit is improved to the reference load to operate, and stable power supply of a power grid is ensured. The novel hybrid power generation system is constructed by fully utilizing the heat storage characteristic of the fused salt and combining the flexible scheduling capability of the gas turbine unit, so that the operation flexibility is improved, the fuel consumption is reduced, and the energy utilization efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar molten salt heat storage and gas-steam combined cycle power generation, and in particular to a gas-steam combined cycle power generation system with integrated heat storage and an operation method thereof. Background Art

[0002] In today's era, the global energy structure is accelerating the transformation from fossil energy to renewable energy. As an efficient, flexible and relatively clean power generation technology, gas-steam combined cycle has an important strategic position and development prospects. This technology combines the advantages of gas turbines and steam turbines. The dual-cycle structure significantly improves the power generation efficiency of the unit, usually up to about 60%, which is much higher than most coal-fired power generation units. However, gas-steam combined cycle units are difficult to promote and apply on a large scale due to their high operating costs and harsh operating conditions. Renewable energy sources such as solar energy and wind energy have lower operating costs and higher environmental performance, but are constrained by the intermittent and unstable output. In this context, renewable energy systems such as solar molten salt heat storage have the potential for coupled development with gas-steam combined cycle, that is, solar molten salt heat storage units provide auxiliary heat sources for gas-steam combined cycle power generation, reducing the loss of natural gas; and the rapid response capability of gas-steam combined cycle units can make up for the shortcomings of solar thermal molten salt power generation on rainy days or at night, ensuring the stable power supply of the power grid. However, in the existing patents, not only is the energy utilization form of the gas-steam combined cycle unit coupled with solar energy relatively simple, but the configuration design and operation control method for coupling the solar molten salt heat storage technology with the gas-steam combined cycle system are even more lacking. Summary of the invention

[0003] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a gas-steam combined cycle power generation system with integrated heat storage and an operation method thereof, which fully utilizes the peak-shaving potential of solar molten salt heat storage, combines the flexible scheduling capability of the gas turbine unit, and coordinates the three-pressure reheat steam cycle unit to achieve the cascade utilization of energy, reduce fuel consumption and heat loss, and improve the energy conversion efficiency as a whole.

[0004] In order to achieve the above object, the present invention adopts the following technical solution:

[0005] A gas-steam combined cycle power generation system with integrated heat storage includes a gas turbine power generation unit, a molten salt heat storage unit and a waste heat boiler steam power generation unit; wherein,

[0006] The gas turbine power generation unit comprises a first generator 1, a compressor 2, a combustion chamber 3, and a gas turbine 4; air is introduced into one end of the compressor 2, and the other end is connected to the combustion chamber 3, fuel is introduced into the combustion chamber 3, the outlet of the combustion chamber 3 is connected to the inlet of the gas turbine 4, the outlet of the gas turbine 4 is connected to the gas pipeline inlet of the waste heat boiler 5 of the waste heat boiler steam power generation unit, and the feed water in the waste heat boiler 5 is heated, the gas pipeline outlet of the waste heat boiler 5 is connected to the gas inlet of the feed water heater 12, and the gas is discharged into the environment after heat exchange with the feed water, and the compressor 2 and the gas turbine 4 are connected to the first generator 1 through a transmission shaft;

[0007] The molten salt heat storage unit includes a heliostat 18, a tower collector 17, a molten salt-water heat exchanger 13, a molten salt-steam heat exchanger 14, a high-temperature molten salt storage tank 16, a high-temperature molten salt pump 15, a low-temperature molten salt storage tank 20 and a low-temperature molten salt pump 19; the heliostat 18 reflects and focuses sunlight to the tower collector 17, the tower collector 17 is connected to the inlet of the high-temperature molten salt storage tank 16, the outlet of the high-temperature molten salt storage tank 16 is connected to the molten salt inlet of the molten salt-steam heat exchanger 14 through the high-temperature molten salt pump 15, the molten salt outlet of the molten salt-steam heat exchanger 14 is connected to the molten salt inlet of the molten salt-water heat exchanger 13, the molten salt outlet of the molten salt-water heat exchanger 13 is connected to the inlet of the low-temperature molten salt storage tank 20, and the outlet of the low-temperature molten salt storage tank 20 is connected to the tower collector 17 through the low-temperature molten salt pump 19 to circulate and heat the molten salt;

[0008] The waste heat boiler steam power generation unit includes a waste heat boiler 5, a high-pressure cylinder 6, an intermediate-pressure cylinder 7, a low-pressure cylinder 8, a second generator 9, a condenser 10, a condensate pump 11, a feed water heater 12, a molten salt-water heat exchanger 13 and a molten salt-steam heat exchanger 14; the superheated steam outlet of the waste heat boiler 5 is connected to the inlet of the high-pressure cylinder 6, the outlet of the high-pressure cylinder 6 is connected to the steam inlet of the molten salt-steam heat exchanger 14, the outlet of the high-pressure cylinder 6 is connected to the reheated steam inlet of the waste heat boiler 5, the second valve 22 is connected to the pipeline between the high-pressure cylinder 6 and the molten salt-steam heat exchanger 14, the first valve 21 is connected to the pipeline between the high-pressure cylinder 6 and the waste heat boiler 5, the steam outlet of the molten salt-steam heat exchanger 14 is connected to the inlet of the intermediate-pressure cylinder 7, the reheated steam outlet of the waste heat boiler 5 is connected to the inlet of the intermediate-pressure cylinder 7, the reheated steam outlet of the intermediate-pressure cylinder 7 is connected to the reheated steam outlet ... The steam outlet is connected to the inlet of the intermediate pressure cylinder 7, the outlet of the intermediate pressure cylinder 7 is connected to the inlet of the low pressure cylinder 8, the outlet of the low pressure cylinder 8 is connected to the steam inlet of the condenser 10, the feed water outlet of the condenser 10 is connected to the feed water inlet of the feed water heater 12 through the condensate pump 11, the feed water outlet of the feed water heater 12 is connected to the feed water inlet of the molten salt-water heat exchanger 13, the fourth valve 24 is connected to the pipeline between the feed water heater 12 and the molten salt-water heat exchanger 13, the feed water outlet of the molten salt-water heat exchanger 13 is connected to the feed water working medium inlet of the waste heat boiler 5, and undergoes cyclic heating of high-temperature fuel gas, the third valve 23 is connected to the pipeline between the feed water heater 12 and the waste heat boiler 5, the high pressure cylinder 6, the intermediate pressure cylinder 7, and the low pressure cylinder 8 are connected to the second generator 9 through the transmission shaft.

[0009] Furthermore, the heliostat 18 reflects sunlight to the tower collector 17 by concentrating light, heats the molten salt heat storage medium to 585-590°C, and then sends it to the high-temperature molten salt storage tank 16. The high-temperature molten salt is first passed into the molten salt-steam heat exchanger 14 to heat the outlet steam of the high-pressure cylinder 6 to 543-550°C, and then the molten salt enters the molten salt-water heat exchanger 13 to preheat the inlet feed water of the waste heat boiler 5 to 125-129°C. After heat exchange, the molten salt enters the low-temperature molten salt storage tank 20 for storage, and finally returns to the tower collector 17 to repeat this process.

[0010] Furthermore, in the waste heat boiler steam power generation unit, the feed water heater 12, the molten salt-water heat exchanger 13 and the molten salt-steam heat exchanger 14 all adopt shell and tube heat exchangers; wherein, in the molten salt-water heat exchanger 13, the shell side working fluid is molten salt, the inlet temperature is 280-287°C, and the outlet temperature is 132-138°C, and the tube side working fluid is water, the inlet temperature is 72-80°C, and the outlet temperature is 125-129°C; in the molten salt-steam heat exchanger 14, the shell side working fluid is high-temperature molten salt, the inlet temperature is 572-580°C, and the outlet temperature is 290-295°C, and the tube side working fluid is steam, the inlet temperature is 272-278°C, and the outlet temperature is 543-550°C.

[0011] Furthermore, the high temperature molten salt storage tank 16 and the low temperature molten salt storage tank 20 are made of quaternary molten salt (54.5% KNO 3 , 9.1%NaNO 3 、18.2%Ca(NO 3 ) 2 and 18.2% LiNO 3 ) as a heat storage medium, the operating temperature range is 130 ~ 590 ° C.

[0012] Furthermore, the heliostats 18 are arranged with the tower collector 17 as the center and extend outwards along an Archimedean spiral.

[0013] Furthermore, the compressor 2 in the gas turbine power generation unit adopts an axial flow compressor, which is composed of 10 to 18 compressor stages, and the inlet and outlet comprehensive pressure ratio can reach 21.

[0014] Furthermore, the first generator 1, the compressor 2 and the gas turbine 4 are coaxially connected.

[0015] The operating method of the gas-steam combined cycle power generation system with integrated heat storage,

[0016] 1) When the sunshine is sufficient, the molten salt heat storage unit, the gas turbine power generation unit and the waste heat boiler steam power generation unit all start to work; specifically, the second valve 22 on the branch road entering the molten salt-steam heat exchanger 14 and the fourth valve 24 on the branch road entering the molten salt-water heat exchanger 13 are opened, the first valve 21 on the branch road entering the waste heat boiler 5 and the third valve 23 on the branch road entering the waste heat boiler 5 are closed, and the inlet air volume of the compressor 2 and the fuel addition volume of the combustion chamber 3 are reduced; the low-temperature molten salt pump 19 is started to introduce the molten salt stored in the low-temperature molten salt storage tank 20 into the tower collector 17 to absorb solar heat, and enter the high-temperature molten salt after heat exchange. The salt storage tank 15 is gathered. After the temperature of the high-temperature molten salt storage tank 15 is stabilized, the high-temperature molten salt pump 15 is turned on to introduce the high-temperature molten salt into the molten salt-steam heat exchanger 14 to reheat the steam at the outlet of the high-pressure cylinder 6 in the waste heat boiler steam power generation unit, and the steam performs work in the medium-pressure cylinder 7 and the low-pressure cylinder 8; the molten salt after heat exchange then enters the molten salt-water heat exchanger 13 to preheat the inlet feed water of the waste heat boiler 5, and the cooled molten salt flows back to the low-temperature molten salt storage tank 20 for storage, and then is pumped into the tower collector 17 for a circulating heating process; the outlet gas of the waste heat boiler 5 is preliminarily preheated by the feed water heater 12 to the outlet condensate of the condensate pump 11;

[0017] 2) When the sunshine is insufficient, the molten salt heat storage unit stops running, and the gas turbine power generation unit and the waste heat boiler steam power generation unit start to operate independently; specifically, the first valve 21 on the branch entering the waste heat boiler 5 and the third valve 23 on the branch entering the waste heat boiler 5 are opened, and the second valve 22 on the branch entering the molten salt-steam heat exchanger 14 and the fourth valve 24 on the branch entering the molten salt-water heat exchanger 13 are closed, and the medium-pressure main steam at the outlet of the high-pressure cylinder 6 enters the medium-pressure cylinder 7 to perform work after being reheated by the waste heat boiler 5, and the feed water heater 12 preheats the condensate and then directly enters the waste heat boiler 5 to exchange heat with the gas, and at the same time, the air volume at the inlet of the compressor 2 and the fuel addition volume of the combustion chamber 3 are restored to normal operating conditions.

[0018] Furthermore, the molten salt heat storage unit has a heat storage time of 8 to 12 hours; the gas turbine power generation unit is equipped with a low-nitrogen combustion chamber and an adjustable guide vane compressor.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The present invention integrates solar molten salt heat storage into a gas-steam combined cycle unit, using solar energy as an auxiliary heat source, reducing the consumption of fuels such as natural gas and reducing the operating cost of the unit. At the same time, through the circulation gradient heating of the two-stage molten salt heat exchanger, the thermodynamic parameters of the waste heat boiler feed water and the medium-pressure main steam of the steam turbine are improved. Compared with the conventional solar thermal molten salt energy storage system, the cycle thermal efficiency of the entire unit is further improved;

[0021] (2) Based on the flexible adjustment performance of the gas turbine power generation unit, the present invention combines the large heat capacity and good thermal stability of the molten salt heat storage technology to further buffer the intermittent and fluctuating nature of solar energy, which is conducive to the stable operation and deep flexible peak regulation of the entire system, and can ensure continuous energy supply in extreme weather or at night, thereby enhancing the utilization rate of the overall unit equipment;

[0022] (3) The present invention utilizes a quaternary molten salt as a heat storage medium. The working range of the molten salt can better match the heat exchange process with water and steam, reduce the heat loss of the heat exchange process, and improve the energy utilization efficiency of the entire integrated system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a gas-steam combined cycle power generation system with integrated heat storage according to the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the preferred implementation examples described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0025] like Figure 1As shown, the present invention provides a gas-steam combined cycle power generation system with integrated heat storage, including a gas turbine power generation unit, a molten salt heat storage unit and a waste heat boiler steam power generation unit; wherein,

[0026] The gas turbine power generation unit comprises a first generator 1, a compressor 2, a combustion chamber 3, and a gas turbine 4; air is introduced into one end of the compressor 2, and the other end is connected to the combustion chamber 3, fuel is introduced into the combustion chamber 3, the outlet of the combustion chamber 3 is connected to the inlet of the gas turbine 4, the outlet of the gas turbine 4 is connected to the gas pipeline inlet of the waste heat boiler 5 of the waste heat boiler steam power generation unit, and the feed water in the waste heat boiler 5 is heated, the gas pipeline outlet of the waste heat boiler 5 is connected to the gas inlet of the feed water heater 12, and the gas is discharged into the environment after heat exchange with the feed water, and the compressor 2 and the gas turbine 4 are connected to the first generator 1 through a transmission shaft;

[0027] The molten salt heat storage unit includes a heliostat 18, a tower collector 17, a molten salt-water heat exchanger 13, a molten salt-steam heat exchanger 14, a high-temperature molten salt storage tank 16, a high-temperature molten salt pump 15, a low-temperature molten salt storage tank 20 and a low-temperature molten salt pump 19; the heliostat 18 reflects and focuses sunlight to the tower collector 17, the tower collector 17 is connected to the inlet of the high-temperature molten salt storage tank 16, the outlet of the high-temperature molten salt storage tank 16 is connected to the molten salt inlet of the molten salt-steam heat exchanger 14 through the high-temperature molten salt pump 15, the molten salt outlet of the molten salt-steam heat exchanger 14 is connected to the molten salt inlet of the molten salt-water heat exchanger 13, the molten salt outlet of the molten salt-water heat exchanger 13 is connected to the inlet of the low-temperature molten salt storage tank 20, and the outlet of the low-temperature molten salt storage tank 20 is connected to the tower collector 17 through the low-temperature molten salt pump 19 to circulate and heat the molten salt;

[0028] The waste heat boiler steam power generation unit includes a waste heat boiler 5, a high-pressure cylinder 6, an intermediate-pressure cylinder 7, a low-pressure cylinder 8, a second generator 9, a condenser 10, a condensate pump 11, a feed water heater 12, a molten salt-water heat exchanger 13 and a molten salt-steam heat exchanger 14; the superheated steam outlet of the waste heat boiler 5 is connected to the inlet of the high-pressure cylinder 6, the outlet of the high-pressure cylinder 6 is connected to the steam inlet of the molten salt-steam heat exchanger 14, the outlet of the high-pressure cylinder 6 is connected to the reheated steam inlet of the waste heat boiler 5, the second valve 22 is connected to the pipeline between the high-pressure cylinder 6 and the molten salt-steam heat exchanger 14, the first valve 21 is connected to the pipeline between the high-pressure cylinder 6 and the waste heat boiler 5, the steam outlet of the molten salt-steam heat exchanger 14 is connected to the inlet of the intermediate-pressure cylinder 7, the reheated steam outlet of the waste heat boiler 5 is connected to the inlet of the intermediate-pressure cylinder 7, the reheated steam outlet of the intermediate-pressure cylinder 7 is connected to the reheated steam outlet ... The steam outlet is connected to the inlet of the intermediate pressure cylinder 7, the outlet of the intermediate pressure cylinder 7 is connected to the inlet of the low pressure cylinder 8, the outlet of the low pressure cylinder 8 is connected to the steam inlet of the condenser 10, the feed water outlet of the condenser 10 is connected to the feed water inlet of the feed water heater 12 through the condensate pump 11, the feed water outlet of the feed water heater 12 is connected to the feed water inlet of the molten salt-water heat exchanger 13, the fourth valve 24 is connected to the pipeline between the feed water heater 12 and the molten salt-water heat exchanger 13, the feed water outlet of the molten salt-water heat exchanger 13 is connected to the feed water working medium inlet of the waste heat boiler 5, and undergoes cyclic heating of high-temperature fuel gas, the third valve 23 is connected to the pipeline between the feed water heater 12 and the waste heat boiler 5, the high pressure cylinder 6, the intermediate pressure cylinder 7, and the low pressure cylinder 8 are connected to the second generator 9 through the transmission shaft.

[0029] Furthermore, the heliostat 18 reflects sunlight to the tower collector 17 by concentrating light, and after heating the molten salt heat storage medium to 585-590°C, it is sent to the high-temperature molten salt storage tank 16, and then the high-temperature molten salt is first passed into the molten salt-steam heat exchanger 14 to heat the outlet steam of the high-pressure cylinder 6 to 543-550°C, and then the molten salt enters the molten salt-water heat exchanger 13 to preheat the inlet feed water of the waste heat boiler 5 to 125-129°C, and after heat exchange, the molten salt enters the low-temperature molten salt storage tank 20 for storage, and finally returns to the tower collector 17 to repeat this process. In this way, the cascade utilization of energy can be achieved, by using high-grade energy to reheat the outlet steam of the high-pressure cylinder 6 and using low-grade energy to preheat the inlet feed water of the waste heat boiler 5, which promotes the precise matching of energy supply and demand, reduces energy waste, and significantly improves the overall energy utilization efficiency.

[0030] Furthermore, in the waste heat boiler steam power generation unit, the feed water heater 12, the molten salt-water heat exchanger 13 and the molten salt-steam heat exchanger 14 all adopt shell and tube heat exchangers; wherein, in the molten salt-water heat exchanger 13, the shell side working fluid is molten salt, the inlet temperature is 280-287°C, and the outlet temperature is 132-138°C, and the tube side working fluid is water, the inlet temperature is 72-80°C, and the outlet temperature is 125-129°C; in the molten salt-steam heat exchanger 14, the shell side working fluid is high-temperature molten salt, the inlet temperature is 572-580°C, and the outlet temperature is 290-295°C, and the tube side working fluid is steam, the inlet temperature is 272-278°C, and the outlet temperature is 543-550°C. This can ensure the high efficiency of the heat exchange process and is beneficial to the maintenance of the equipment. At the same time, the two fluid working media in the molten salt-water heat exchanger 13 present co-current heat exchange, and the structure is relatively simple, which is easy to install and maintain. The inlet temperature difference of the heat exchanger is the largest, and the inlet feed water of the waste heat boiler 5 can be quickly preheated, and gradually decreases with the flow direction, so that the temperature gradient in the heat exchanger is relatively uniform, which can avoid local overheating and ensure the safety and reliability of equipment operation; and the two fluid working media in the molten salt-steam heat exchanger 14 present counter-current heat exchange, so that the temperature difference between the two remains relatively uniform and large during the entire heat exchange process, and the temperature difference can be fully utilized to achieve the most ideal heat exchange state, which greatly improves the heat exchange efficiency.

[0031] Furthermore, the high temperature molten salt storage tank 16 and the low temperature molten salt storage tank 20 are made of quaternary molten salt (54.5% KNO 3 , 9.1%NaNO 3 、18.2%Ca(NO 3 ) 2 and 18.2% LiNO 3 ) as a heat storage medium, the operating temperature range is 130 ~ 590 ° C. This expands the operating range of the working medium and ensures the high efficiency of the heat storage unit.

[0032] Furthermore, the heliostats 18 are arranged in an Archimedean spiral line with the tower collector 17 as the center, which not only takes into account the changes in the solar altitude angle in different seasons, but also optimizes the optical path design, improves the energy collection efficiency, reduces the system complexity, and enhances the stability and adaptability of the heat collection unit.

[0033] Furthermore, the gas turbine power generation unit adopts an axial flow compressor, which is composed of 10 to 18 compressors, and the inlet and outlet comprehensive pressure ratio can reach 21. This can ensure a higher isentropic efficiency, gradually increase the air pressure, reduce energy loss, and help improve the thermal efficiency of the gas turbine unit. At the same time, the high pressure ratio can increase the combustion temperature and pressure of the combustion chamber, which is conducive to improving the combustion efficiency and power generation efficiency, reducing the emission of pollutants, and ensuring the thermal economy of the system.

[0034] Furthermore, the first generator 1, the compressor 2 and the gas turbine 4 are coaxially connected. This ensures that the equipment operates at the same frequency, reduces unnecessary losses, and maintains high efficiency and stability of system operation.

[0035] The described method for operating a gas-steam combined cycle power generation system with integrated heat storage is that when there is sufficient sunshine, the gas turbine power generation unit switches to a low-load operation mode, the molten salt heat storage unit heats to generate reheat steam, and preheats the inlet feed water of the waste heat boiler, thereby enhancing the peak-shaving depth of the gas-steam combined cycle; when there is insufficient sunshine, the molten salt heat storage unit continuously releases the stored heat to maintain the stability of the main steam parameters until the heat storage capacity reaches the critical threshold and then exits operation, at which time the gas turbine power generation unit is increased to the base load operation to ensure stable power supply to the power grid. The specific method is as follows:

[0036] 1) When the sunshine is sufficient, the molten salt heat storage unit, the gas turbine power generation unit and the waste heat boiler steam power generation unit all start to work; specifically, the second valve 22 on the branch road entering the molten salt-steam heat exchanger 14 and the fourth valve 24 on the branch road entering the molten salt-water heat exchanger 13 are opened, the first valve 21 on the branch road entering the waste heat boiler 5 and the third valve 23 on the branch road entering the waste heat boiler 5 are closed, and the inlet air volume of the compressor 2 and the fuel addition volume of the combustion chamber 3 are reduced; the low-temperature molten salt pump 19 is started to introduce the molten salt stored in the low-temperature molten salt storage tank 20 into the tower collector 17 to absorb solar heat, and enter the high-temperature molten salt after heat exchange. The salt storage tank 15 is gathered. After the temperature of the high-temperature molten salt storage tank 15 is stabilized, the high-temperature molten salt pump 15 is turned on to introduce the high-temperature molten salt into the molten salt-steam heat exchanger 14 to reheat the steam at the outlet of the high-pressure cylinder 6 in the waste heat boiler steam power generation unit, and the steam performs work in the medium-pressure cylinder 7 and the low-pressure cylinder 8; the molten salt after heat exchange then enters the molten salt-water heat exchanger 13 to preheat the inlet feed water of the waste heat boiler 5, and the cooled molten salt flows back to the low-temperature molten salt storage tank 20 for storage, and then is pumped into the tower collector 17 for a circulating heating process; the outlet gas of the waste heat boiler 5 is preliminarily preheated by the feed water heater 12 to the outlet condensate of the condensate pump 11;

[0037] 2) When the sunshine is insufficient, the molten salt heat storage unit stops running, and the gas turbine power generation unit and the waste heat boiler steam power generation unit start to operate independently; specifically, the first valve 21 on the branch entering the waste heat boiler 5 and the third valve 23 on the branch entering the waste heat boiler 5 are opened, and the second valve 22 on the branch entering the molten salt-steam heat exchanger 14 and the fourth valve 24 on the branch entering the molten salt-water heat exchanger 13 are closed, and the medium-pressure main steam at the outlet of the high-pressure cylinder 6 enters the medium-pressure cylinder 7 to perform work after being reheated by the waste heat boiler 5, and the feed water heater 12 preheats the condensate and then directly enters the waste heat boiler 5 to exchange heat with the gas, and at the same time, the air volume at the inlet of the compressor 2 and the fuel addition volume of the combustion chamber 3 are restored to normal operating conditions.

[0038] Furthermore, the molten salt heat storage unit has a heat storage time of 8 to 12 hours; the gas turbine power generation unit is equipped with a low-nitrogen combustion chamber and an adjustable guide vane compressor. This ensures that the unit has the ability to adjust across days and large-scale consumption, and at the same time, the load adjustment range of the gas turbine power generation unit can be extended to 25%-110%, and the ramp rate can reach 8MW / min, which can serve as a fast adjustment source for the grid frequency response and meet the requirements of flexible peak-shaving operation.

Claims

1. A gas-steam combined cycle power generation system with integrated heat storage, characterized in that: The system includes a gas turbine power generation unit, a molten salt heat storage unit and a waste heat boiler steam power generation unit; wherein, The gas turbine power generation unit comprises a first generator (1), a compressor (2), a combustion chamber (3), and a gas turbine (4); air is introduced into one end of the compressor (2), and the other end is connected to the combustion chamber (3); fuel is introduced into the combustion chamber (3); the outlet of the combustion chamber (3) is connected to the inlet of the gas turbine (4); the outlet of the gas turbine (4) is connected to the gas pipeline inlet of the waste heat boiler (5) of the waste heat boiler steam power generation unit to heat the feed water in the waste heat boiler (5); the gas pipeline outlet of the waste heat boiler (5) is connected to the gas inlet of the feed water heater (12); the gas is discharged into the environment after heat exchange with the feed water; the compressor (2) and the gas turbine (4) are connected to the first generator (1) via a transmission shaft; The molten salt heat storage unit comprises a heliostat (18), a tower collector (17), a molten salt-water heat exchanger (13), a molten salt-steam heat exchanger (14), a high-temperature molten salt storage tank (16), a high-temperature molten salt pump (15), a low-temperature molten salt storage tank (20) and a low-temperature molten salt pump (19); the heliostat (18) reflects and focuses sunlight onto the tower collector (17), the tower collector (17) is connected to the inlet of the high-temperature molten salt storage tank (16), and the high-temperature molten salt storage tank (15) is connected to the inlet of the high-temperature molten salt storage tank (16). The outlet of the molten salt tank (6) is connected to the molten salt inlet of the molten salt-steam heat exchanger (14) through a high-temperature molten salt pump (15), the molten salt outlet of the molten salt-steam heat exchanger (14) is connected to the molten salt inlet of the molten salt-water heat exchanger (13), the molten salt outlet of the molten salt-water heat exchanger (13) is connected to the inlet of the low-temperature molten salt storage tank (20), and the outlet of the low-temperature molten salt storage tank (20) is connected to the tower collector (17) through a low-temperature molten salt pump (19), so that the molten salt is circulated and heated; The waste heat boiler steam power generation unit comprises a waste heat boiler (5), a high-pressure cylinder (6), a medium-pressure cylinder (7), a low-pressure cylinder (8), a second generator (9), a condenser (10), a condensate pump (11), a feed water heater (12), a molten salt-water heat exchanger (13) and a molten salt-steam heat exchanger (14); the superheated steam outlet of the waste heat boiler (5) is connected to the inlet of the high-pressure cylinder (6), the outlet of the high-pressure cylinder (6) is connected to the steam inlet of the molten salt-steam heat exchanger (14), the outlet of the high-pressure cylinder (6) is connected to the reheated steam inlet of the waste heat boiler (5), the second valve (22) is connected to the pipeline between the high-pressure cylinder (6) and the molten salt-steam heat exchanger (14), the first valve (21) is connected to the pipeline between the high-pressure cylinder (6) and the waste heat boiler (5), the steam outlet of the molten salt-steam heat exchanger (14) is connected to the inlet of the medium-pressure cylinder (7), the outlet of the waste heat boiler (5) is connected to the reheated steam inlet The reheat steam outlet is connected to the inlet of the intermediate pressure cylinder (7), the outlet of the intermediate pressure cylinder (7) is connected to the inlet of the low pressure cylinder (8), the outlet of the low pressure cylinder (8) is connected to the steam inlet of the condenser (10), the feed water outlet of the condenser (10) is connected to the feed water inlet of the feed water heater (12) through the condensate pump (11), the feed water outlet of the feed water heater (12) is connected to the feed water inlet of the molten salt-water heat exchanger (13), the fourth valve (24) is connected to the pipeline between the feed water heater (12) and the molten salt-water heat exchanger (13), the feed water outlet of the molten salt-water heat exchanger (13) is connected to the feed water working medium inlet of the waste heat boiler (5), and is subjected to the circulation heating of the high-temperature combustion gas, the third valve (23) is connected to the pipeline between the feed water heater (12) and the waste heat boiler (5), and the high pressure cylinder (6), the intermediate pressure cylinder (7), and the low pressure cylinder (8) are connected to the second generator (9) through the transmission shaft.

2. A gas-steam combined cycle power generation system with integrated heat storage according to claim 1, characterized in that: The heliostat (18) reflects sunlight to the tower collector (17) by concentrating light, and the molten salt heat storage medium is heated to 585-590° C., and then sent to the high-temperature molten salt storage tank (16). Then, the high-temperature molten salt is first passed into the molten salt-steam heat exchanger (14) to heat the outlet steam of the high-pressure cylinder (6) to 543-550° C., and then the molten salt enters the molten salt-water heat exchanger (13) to preheat the inlet feed water of the waste heat boiler (5) to 125-129° C. After heat exchange, the molten salt enters the low-temperature molten salt storage tank (20) for storage, and finally returns to the tower collector (17) to repeat this process.

3. The gas-steam combined cycle power generation system with integrated heat storage according to claim 1, characterized in that: In the waste heat boiler steam power generation unit, the feed water heater (12), the molten salt-water heat exchanger (13) and the molten salt-steam heat exchanger (14) all adopt shell and tube heat exchangers; wherein, in the molten salt-water heat exchanger (13), the shell side working fluid is molten salt, the inlet temperature is 280-287°C, and the outlet temperature is 132-138°C, and the tube side working fluid is water, the inlet temperature is 72-80°C, and the outlet temperature is 125-129°C; in the molten salt-steam heat exchanger (14), the shell side working fluid is high temperature molten salt, the inlet temperature is 572-580°C, and the outlet temperature is 290-295°C, and the tube side working fluid is steam, the inlet temperature is 272-278°C, and the outlet temperature is 543-550°C.

4. The gas-steam combined cycle power generation system with integrated heat storage according to claim 1, characterized in that: The molten salt in the high-temperature molten salt storage tank (16) and the low-temperature molten salt storage tank (20) uses quaternary molten salt as a heat storage medium, and the operating temperature range is 130 to 590° C. The quaternary molten salt is composed of 54.5% KNO3, 9.1% NaNO3, 18.2% Ca(NO3)2 and 18.2% LiNO3.

5. The gas-steam combined cycle power generation system with integrated heat storage according to claim 1, characterized in that: The heliostats (18) are arranged with the tower collector (17) as the center and extend outwards along an Archimedean spiral.

6. A gas-steam combined cycle power generation system with integrated heat storage according to claim 1, characterized in that: The compressor (2) in the gas turbine power generation unit adopts an axial flow compressor, which is composed of 10 to 18 compressor stages, and the inlet and outlet comprehensive pressure ratio can reach 21.

7. The gas-steam combined cycle power generation system with integrated heat storage according to claim 1, characterized in that: The first generator (1), the compressor (2) and the gas turbine (4) are coaxially connected.

8. The method for operating a gas-steam combined cycle power generation system with integrated heat storage according to any one of claims 1 to 7, characterized in that: 1) When the sunshine is sufficient, the molten salt heat storage unit, the gas turbine power generation unit and the waste heat boiler steam power generation unit all start to work; specifically, the second valve (22) on the branch line entering the molten salt-steam heat exchanger (14) and the fourth valve (24) on the branch line entering the molten salt-water heat exchanger (13) are opened, the first valve (21) on the branch line entering the waste heat boiler (5) and the third valve (23) on the branch line entering the waste heat boiler (5) are closed, and the inlet air volume of the compressor (2) and the fuel addition volume of the combustion chamber (3) are reduced; the low-temperature molten salt pump (19) is started, and the molten salt stored in the low-temperature molten salt storage tank (20) is introduced into the tower collector (17) to absorb solar heat, and after heat exchange, the molten salt enters the high-temperature molten salt The high-temperature molten salt is gathered in the storage tank (15). After the temperature of the high-temperature molten salt storage tank (15) is stabilized, the high-temperature molten salt pump (15) is turned on to introduce the high-temperature molten salt into the molten salt-steam heat exchanger (14) to reheat the outlet steam of the high-pressure cylinder (6) in the waste heat boiler steam power generation unit, and the steam performs work in the medium-pressure cylinder (7) and the low-pressure cylinder (8); the molten salt after heat exchange then enters the molten salt-water heat exchanger (13) to preheat the inlet feed water of the waste heat boiler (5), and the cooled molten salt flows back to the low-temperature molten salt storage tank (20) for storage, and then is pumped into the tower collector (17) for a circulating heating process; the outlet gas of the waste heat boiler (5) is preliminarily preheated by the feed water heater (12) to the outlet condensate of the condensate pump (11); 2) When the sunshine is insufficient, the molten salt heat storage unit stops operating, and the gas turbine power generation unit and the waste heat boiler steam power generation unit start to operate independently; specifically, the first valve (21) on the branch line entering the waste heat boiler (5) and the third valve (23) on the branch line entering the waste heat boiler (5) are opened, and the second valve (22) on the branch line entering the molten salt-steam heat exchanger (14) and the fourth valve (24) on the branch line entering the molten salt-water heat exchanger (13) are closed, and the medium-pressure main steam at the outlet of the high-pressure cylinder (6) enters the medium-pressure cylinder (7) to perform work after being reheated by the waste heat boiler (5), and the feed water heater (12) preheats the condensate and then directly enters the waste heat boiler (5) to exchange heat with the gas, and at the same time, the air volume at the inlet of the compressor (2) and the fuel addition volume of the combustion chamber (3) are restored to normal operating conditions.

9. The method for operating a gas-steam combined cycle power generation system with integrated heat storage according to claim 8, characterized in that: The molten salt heat storage unit can store heat for 8 to 12 hours; the gas turbine power generation unit is equipped with a low-nitrogen combustion chamber and an adjustable guide vane compressor.

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