Molten salt heat storage peak regulation system and operation method for supercritical carbon dioxide power generation unit

Abstract

The present invention discloses a molten salt heat storage peak-shaving system and an operation method for a supercritical carbon dioxide power generation unit, the system comprising a supercritical carbon dioxide circulation power generation system consisting of a boiler, a high-pressure turbine, a low-pressure turbine, a high-temperature regenerator, a low-temperature regenerator, a recompressor, a precooler, and a main compressor, and two molten salt heat storage peak-shaving systems consisting of a molten salt cold tank, a molten salt hot tank, a heat storage molten salt regulating valve, a heat storage molten salt pump, a heat release molten salt regulating valve, a heat release molten salt pump, a heat storage molten salt heat exchanger, and a heat release molten salt heat exchanger. When the grid dispatching load is reduced, the system heats the molten salt by extracting the high-temperature working fluid at the boiler outlet and stores it in the hot tank. When the grid dispatching load increases, the stored high-temperature molten salt can be used to quickly heat part of the circulating working fluid to enter the turbine to do work, and the molten salt releases heat, thereby realizing the function of heat storage peak-shaving in the supercritical carbon dioxide circulation power generation system, greatly promoting the grid's consumption of renewable energy power generation.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation, and in particular to a molten salt heat storage peak regulation system and an operation method for a supercritical carbon dioxide power generation unit. Background Art

[0002] As a circulating working fluid, carbon dioxide is non-toxic, non-flammable, low in corrosiveness, high in thermal stability, and has low critical parameters. Carbon dioxide in a supercritical state has the characteristics of high density and high heat transfer efficiency of liquids, as well as low viscosity and strong flowability of gases. The density of carbon dioxide increases sharply near the critical point, and its compressibility decreases, which reduces the power consumption of compression and increases the system cycle efficiency. Compared with the traditional steam Rankine cycle, supercritical carbon dioxide cycle power generation technology has higher cycle thermal efficiency, compact equipment, simple layout, good inheritance, and can be realized based on existing materials, avoiding the development of expensive high-temperature nickel-based alloy materials. It is an important development direction of thermal power generation technology.

[0003] With the rapid development of renewable energy power generation technologies such as solar energy and wind energy and their installed capacity, the proportion of clean energy in my country's power structure has continued to increase, but its power generation process has obvious volatility, intermittency and regional limitations, making it difficult to stably and reliably meet the power demand of the power grid. In order to smooth out the volatility of renewable energy power generation and effectively absorb clean energy such as solar energy and wind energy, thermal power generation, which is mainly coal-fired power generation, has developed a variety of peak-shaving technologies, such as condensate throttling, deaerator and condenser hot well water storage, turbine low-pressure cylinder zero output, electric boiler thermoelectric decoupling, turbine bypass heating, coordinated optimization control and other peak-shaving technologies. However, there are problems such as insufficient peak-shaving capacity, long response time, and high operation control requirements, and the existing peak-shaving technologies are all applied to thermal power generating units with steam Rankine cycle. Summary of the invention

[0004] In order to overcome the problems existing in the above-mentioned technologies and improve the grid-connected consumption of renewable energy power generation such as solar energy and wind energy, based on the supercritical carbon dioxide cycle, the present invention proposes a molten salt heat storage peak-shaving system and an operation method for a supercritical carbon dioxide power generation unit. When the grid dispatching load is reduced, the system extracts part of the high-temperature carbon dioxide from the outlet of the boiler superheater and the reheater, exchanges heat with the low-temperature molten salt in the molten salt heat storage system, and stores the molten salt after absorbing heat, while the carbon dioxide after exothermic is re-integrated into the circulating working fluid; when the grid dispatching load is increased, part of the carbon dioxide is diverted from the cold side outlet of the high-temperature regenerator and the outlet of the high-pressure turbine, exchanges heat with the high-temperature molten salt in the molten salt heat release system, stores the molten salt after exothermic, and mixes the high-temperature carbon dioxide after absorbing heat with the circulating working fluid at the inlet of the high- and low-pressure turbines, and enters the high- and low-pressure turbines to perform work, thereby rapidly increasing the power generation capacity of the unit.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The supercritical carbon dioxide power generation unit molten salt heat storage peak-shaving system includes a supercritical carbon dioxide cycle power generation system and two sets of molten salt heat storage peak-shaving systems;

[0007] The supercritical carbon dioxide cycle power generation system comprises a boiler 21, a high-pressure turbine 22, a low-pressure turbine 23, a high-temperature regenerator 24, a low-temperature regenerator 25, a recompressor 26, a precooler 27 and a main compressor 28; the superheater outlet of the boiler 21 is connected to the inlet of the high-pressure turbine 22, the outlet of the high-pressure turbine 22 is connected to the inlet of the reheater of the boiler 21, and the outlet of the reheater of the boiler 21 is connected to the inlet of the low-pressure turbine 23;

[0008] The outlet of the low-pressure turbine 23 is connected to the hot side of the high-temperature regenerator 24 and the low-temperature regenerator 25 in sequence. The hot side outlet of the low-temperature regenerator 25 is divided into two paths, one of which is connected to the inlet of the recompressor 26, and the other is connected to the hot side inlet of the precooler 27;

[0009] The hot side outlet of the precooler 27 is connected to the inlet of the main compressor 28, the outlet of the main compressor 28 is connected to the cold side of the low temperature regenerator 25 and the high temperature regenerator 24 in sequence, the cold side outlet of the high temperature regenerator 24 is connected to the superheater inlet of the boiler 21, and the outlet of the compressor 26 is connected to the cold side outlet of the low temperature regenerator 25;

[0010] The working medium of the supercritical carbon dioxide cycle power generation system is supercritical carbon dioxide;

[0011] The two groups of molten salt heat storage peak-shaving systems include group A and group B, which are respectively connected in sequence: group A molten salt cold tank 1, group A heat storage molten salt regulating valve 2, group A heat storage molten salt pump 3, group A heat storage molten salt heat exchanger 4, group A molten salt hot tank 5, group A exothermic molten salt regulating valve 6, group A exothermic molten salt pump 7 and group A exothermic molten salt heat exchanger 8, and group B molten salt cold tank 11, group B heat storage molten salt regulating valve 12, group B heat storage molten salt pump 13, group B heat storage molten salt heat exchanger 14, group B molten salt hot tank 15, group B exothermic molten salt regulating valve 16, group B exothermic molten salt pump 17 and group B exothermic molten salt heat exchanger 18;

[0012] The outlet of the cold tank 1 of group A molten salt is connected to the cold side inlet of the heat storage molten salt heat exchanger 4 of group A through the heat storage molten salt regulating valve 2 of group A and the heat storage molten salt pump 3 of group A in sequence, and the cold side outlet of the heat storage molten salt heat exchanger 4 of group A is connected to the inlet of the hot tank 5 of group A molten salt;

[0013] The outlet of the hot tank 5 of group A molten salt is connected to the hot side inlet of the heat release molten salt heat exchanger 8 of group A through the heat release molten salt regulating valve 6 of group A and the heat release molten salt pump 7 of group A in sequence, and the hot side outlet of the heat release molten salt heat exchanger 8 of group A is connected to the inlet of the cold tank 1 of group A molten salt;

[0014] The outlet of the group B molten salt cold tank 11 is connected to the cold side inlet of the group B thermal storage molten salt heat exchanger 14 through the group B thermal storage molten salt regulating valve 12 and the group B thermal storage molten salt pump 13 in sequence, and the cold side outlet of the group B thermal storage molten salt heat exchanger 14 is connected to the inlet of the group B molten salt hot tank 15;

[0015] The outlet of the hot tank 15 of group B molten salt is connected to the hot side inlet of the heat release molten salt heat exchanger 18 of group B through the heat release molten salt regulating valve 16 of group B and the heat release molten salt pump 17 of group B in sequence, and the hot side outlet of the heat release molten salt heat exchanger 18 of group B is connected to the inlet of the cold tank 11 of group B molten salt;

[0016] The working medium of the two molten salt heat storage peak-shaving systems is molten salt.

[0017] Furthermore, the two groups of molten salt heat storage peak regulation systems also include a high-pressure turbine inlet regulating valve 9, a boiler inlet regulating valve 10, a low-pressure turbine inlet regulating valve 19, and a high-pressure turbine outlet regulating valve 20;

[0018] The hot side inlet of the heat storage molten salt heat exchanger 4 of group A is connected to the superheater outlet of the boiler 21 through the high-pressure turbine inlet regulating valve 9, the hot side outlet of the heat storage molten salt heat exchanger 4 of group A is connected to the outlet of the high-pressure turbine 22, the cold side inlet of the heat release molten salt heat exchanger 8 of group A is connected to the cold side outlet of the high-temperature regenerator 24 through the boiler inlet regulating valve 10, and the cold side outlet of the heat release molten salt heat exchanger 8 of group A is connected to the inlet of the high-pressure turbine 22;

[0019] The hot side inlet of the group B heat storage molten salt heat exchanger 14 is connected to the reheater outlet of the boiler 21 through the low-pressure turbine inlet regulating valve 19, the hot side outlet of the group B heat storage molten salt heat exchanger 14 is connected to the outlet of the low-pressure turbine 23, the cold side inlet of the group B heat release molten salt heat exchanger 18 is connected to the outlet of the high-pressure turbine 22 through the high-pressure turbine outlet regulating valve 20, and the cold side outlet of the group B heat release molten salt heat exchanger 18 is connected to the inlet of the low-pressure turbine 23.

[0020] The operation method of the molten salt heat storage peak-shaving system of the supercritical carbon dioxide power generation unit is as follows: after the working fluid is pressurized by the main compressor 28, it absorbs heat in the low-temperature regenerator 25, the high-temperature regenerator 24 and the superheater in the boiler 21 in turn, and after the temperature rises, it enters the high-pressure turbine 22 to partially expand and do work. After doing work, the temperature and pressure of the working fluid are reduced, and then it re-enters the reheater of the boiler 21 to continue absorbing heat and heating, and enters the low-pressure turbine 23 to fully expand and do work. After doing work, the working fluid enters the high-temperature regenerator 24 and the low-temperature regenerator 25 in turn to release heat. After releasing heat, the working fluid is divided into two paths, one path is pressurized by the recompressor 26 and then merged into the cold side outlet of the low-temperature regenerator 25, and the other path is cooled and released by the precooler 27 and then enters the main compressor 28 for pressurization, completing a closed cycle;

[0021] When the grid dispatching load is reduced, the high-temperature working fluid extracted from the outlet of the superheater of the boiler 21 is depressurized by the high-pressure turbine inlet regulating valve 9 and then enters the group A heat storage molten salt heat exchanger 4 to release heat. The working fluid after cooling and depressurization is mixed with the working fluid at the outlet of the high-pressure turbine 22 and enters the reheater of the boiler 21 to absorb heat and heat up. The high-temperature working fluid extracted from the outlet of the reheater of the boiler 21 is depressurized by the low-pressure turbine inlet regulating valve 19 and then enters the group B heat storage molten salt heat exchanger 14 to release heat. The working fluid after cooling and depressurization is mixed with the working fluid at the outlet of the low-pressure turbine 23 and enters the high-temperature regenerator 24 to release heat and cool down.

[0022] When the grid dispatching load is reduced, the group A heat storage molten salt regulating valve 2 and / or the group B heat storage molten salt regulating valve 12 are opened, and the low-temperature molten salt in the group A molten salt cold tank 1 passes through the group A heat storage molten salt regulating valve 2 and is pressurized in the group A heat storage molten salt pump 3, and then is transported to the group A heat storage molten salt heat exchanger 4 to absorb heat and heat up, and then is stored in the group A molten salt hot tank 5, and the low-temperature molten salt in the group B molten salt cold tank 11 passes through the group B heat storage molten salt regulating valve 12 and is pressurized in the group B heat storage molten salt pump 13, and then is transported to the group B heat storage molten salt heat exchanger 14 to absorb heat and heat up, and then is stored in the group B molten salt hot tank 15;

[0023] When the grid dispatching load increases, the exothermic molten salt regulating valve 6 of group A and / or the exothermic molten salt regulating valve 16 of group B are opened, and the high-temperature molten salt stored in the molten salt hot tank 5 of group A passes through the exothermic molten salt regulating valve 6 of group A, is pressurized in the exothermic molten salt pump 7 of group A, is transported to the exothermic molten salt heat exchanger 8 of group A for exothermic cooling, and is then stored in the molten salt cold tank 1 of group A; the high-temperature molten salt stored in the molten salt hot tank 15 of group B passes through the exothermic molten salt regulating valve 16 of group B, is pressurized in the exothermic molten salt pump 17 of group B, is transported to the exothermic molten salt heat exchanger 18 of group B for exothermic cooling, and is then stored in the molten salt cold tank 11 of group B;

[0024] When the grid dispatching load increases, the boiler inlet regulating valve 10 is opened, and part of the working fluid at the cold side outlet of the high-temperature regenerator 24 is diverted and sent to the exothermic molten salt heat exchanger 8 of group A to absorb heat and heat up, and then mixed with the inlet working fluid of the high-pressure turbine 22 to enter the high-pressure turbine 22 to do work; the high-pressure turbine outlet regulating valve 20 is opened, and part of the high-pressure turbine outlet working fluid is diverted and sent to the exothermic molten salt heat exchanger 18 of group B to absorb heat and heat up, and then mixed with the inlet working fluid of the low-pressure turbine 23 to enter the low-pressure turbine 23 to do work.

[0025] Furthermore, the two groups of molten salt heat storage peak-shaving systems operate independently of each other. Both groups can be operated at the same time, or one of them can be operated alone. The specific operation mode depends on the grid dispatching load.

[0026] Compared with the prior art, the present invention has the following beneficial technical effects:

[0027] The boiler, high-pressure turbine, low-pressure turbine, high-temperature regenerator, low-temperature regenerator, recompressor, precooler and main compressor in the molten salt heat storage peak-shaving system of the supercritical carbon dioxide power generation unit form a supercritical carbon dioxide cycle power generation unit, which uses supercritical carbon dioxide as a circulating working fluid to generate electricity and has a higher cycle thermal efficiency than the steam Rankine cycle power generation unit.

[0028] Furthermore, the system is equipped with a molten salt heat storage peak-shaving system including a molten salt storage tank, a molten salt pump, a molten salt regulating valve and a molten salt heat exchanger on the supercritical carbon dioxide cycle power generation unit. When the grid dispatching load is reduced, the high-temperature working fluid at the outlet of the boiler superheater and reheater is extracted to heat the molten salt from the cold tank in the heat storage molten salt heat exchanger, and then the molten salt after absorbing heat is stored in the hot tank. When the grid dispatching load increases, the molten salt stored in the hot tank is sent to the heat release molten salt heat exchanger to heat part of the circulating working fluid diverted from the cold side outlet of the high-temperature regenerator and the outlet of the high-pressure turbine. The molten salt after heat release is stored again in the cold tank, and the working fluid after heating enters the high and low pressure turbines to increase work, so as to quickly increase the power generation of the unit. The system realizes the flexible operation of the supercritical carbon dioxide cycle power generation system through the molten salt heat storage peak-shaving system, improves the peak-shaving capacity of the supercritical carbon dioxide power generation unit, and promotes the grid's consumption of renewable energy power generation.

[0029] Furthermore, when meeting the peak load regulation demand of the power grid, the system can ensure the safe and stable operation of the supercritical carbon dioxide boiler under low load conditions through the heat storage of molten salt.

[0030] Furthermore, this system will maximize the peak-shaving capacity of the supercritical carbon dioxide cycle power generation unit and meet the peak-shaving needs of the power grid at different levels by configuring heat storage peak-shaving systems in the high-pressure turbine and low-pressure turbine bypass respectively.

[0031] Furthermore, molten salt as a heat storage medium has the advantages of large heat storage capacity and high cost performance compared to water, thermal oil and solid heat storage. It is being widely used in the field of solar thermal power generation and the technology is relatively mature.

[0032] The operation method of the molten salt heat storage peak-shaving system of the supercritical carbon dioxide power generation unit is to extract part of the high-temperature carbon dioxide from the outlet of the boiler superheater and reheater to heat the molten salt, thereby reducing the work done in the turbine. The stored high-temperature molten salt can also be used to heat the circulating working fluid, allowing it to enter the turbine to increase the work done, so as to rapidly increase the power generation capacity of the unit, thereby realizing the peak-shaving and frequency regulation of the supercritical carbon dioxide circulation power generation unit.

[0033] Furthermore, the two groups of peak-shaving systems in the method can operate one group independently or both groups simultaneously, which has greater operational flexibility and can meet the different degrees of peak-shaving demands and different operating requirements of the power grid for supercritical carbon dioxide cycle power generation units. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a system schematic diagram of the present invention.

[0035] Among them, 1 is a group A molten salt cold tank, 2 is a group A heat storage molten salt regulating valve, 3 is a group A heat storage molten salt pump, 4 is a group A heat storage molten salt heat exchanger, 5 is a group A molten salt hot tank, 6 is a group A heat release molten salt regulating valve, 7 is a group A heat release molten salt pump, 8 is a group A heat release molten salt heat exchanger, 9 is a high-pressure turbine inlet regulating valve, 10 is a boiler inlet regulating valve, 11 is a group B molten salt cold tank, 12 is a group B heat storage molten salt regulating valve, 13 is a group B heat storage molten salt pump, 1 4 is a heat storage molten salt heat exchanger of group B, 15 is a molten salt hot tank of group B, 16 is a heat release molten salt regulating valve of group B, 17 is a heat release molten salt pump of group B, 18 is a heat release molten salt heat exchanger of group B, 19 is a low-pressure turbine inlet regulating valve, 20 is a high-pressure turbine outlet regulating valve, 21 is a boiler, 22 is a high-pressure turbine, 23 is a low-pressure turbine, 24 is a high-temperature regenerator, 25 is a low-temperature regenerator, 26 is a recompressor, 27 is a precooler, and 28 is a main compressor. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0037] The supercritical carbon dioxide cycle has a high cycle thermal efficiency, and can reach the efficiency of the steam Rankine cycle at 700°C at 600°C. It can be realized based on existing materials, and the cycle equipment is compact and simple to arrange, which is an important direction for the development of thermal power generation technology. Molten salt is a safe, stable and efficient heat storage medium, which has great advantages in heat storage. Its application in thermal power generation systems can achieve peak and frequency regulation of units, and promote the power grid to absorb renewable energy power generation such as wind power and solar power.

[0038] The molten salt heat storage peak regulation system of the supercritical carbon dioxide power generation unit of the present invention is as follows: Figure 1 As shown, it includes a supercritical carbon dioxide cycle power generation system and a molten salt heat storage peak regulation system.

[0039] The supercritical carbon dioxide cycle power generation system includes a boiler 21, a high-pressure turbine 22, a low-pressure turbine 23, a high-temperature regenerator 24, a low-temperature regenerator 25, a recompressor 26, a precooler 27 and a main compressor 28; wherein the superheater outlet of the boiler 21 is connected to the inlet of the high-pressure turbine 22, the outlet of the high-pressure turbine 22 is connected to the inlet of the reheater of the boiler 21, the outlet of the reheater of the boiler 21 is connected to the inlet of the low-pressure turbine 23, and the outlet of the low-pressure turbine 23 is connected to the hot side of the high-temperature regenerator 24 and the low-temperature regenerator 25 in sequence. The hot side outlet of the low-temperature regenerator 25 is connected to the inlet of the recompressor 26 and the hot side inlet of the precooler 27 at the same time, the hot side outlet of the precooler 27 is connected to the inlet of the main compressor 28, the outlet of the main compressor 28 is connected to the cold sides of the low-temperature regenerator 25 and the high-temperature regenerator 24 in sequence, the cold side outlet of the high-temperature regenerator 24 is connected to the superheater inlet of the boiler 21, and the outlet of the recompressor 26 is connected to the cold side outlet of the low-temperature regenerator 25, wherein the working medium of the supercritical carbon dioxide cycle power generation system is supercritical carbon dioxide.

[0040] The molten salt heat storage and peak-shaving system includes a group of molten salt cold tanks 1, a group of heat storage molten salt regulating valves 2, a group of heat storage molten salt pumps 3, a group of heat storage molten salt heat exchangers 4, a group of molten salt hot tanks 5, a group of exothermic molten salt regulating valves 6, a group of exothermic molten salt pumps 7 and a group of exothermic molten salt heat exchangers 8 connected in sequence, which form a group of molten salt heat storage and peak-shaving systems; and a group of molten salt cold tanks 11, a group of heat storage molten salt regulating valves 12, a group of heat storage molten salt pumps 13, a group of heat storage molten salt heat exchangers 14, a group of molten salt hot tanks 15, a group of exothermic molten salt regulating valves 16, a group of exothermic molten salt pumps 17 and a group of exothermic molten salt heat exchangers 18 connected in sequence, which form another group of molten salt heat storage and peak-shaving systems; and also includes a high-pressure turbine inlet regulating valve 9, a boiler inlet regulating valve 10, a low-pressure turbine inlet regulating valve 19, and a high-pressure turbine outlet regulating valve 20.

[0041] The outlet of the group A molten salt cold tank 1 passes through the group A heat storage molten salt regulating valve 2 and the group A heat storage molten salt pump 3 in sequence and is connected to the cold side inlet of the group A heat storage molten salt heat exchanger 4, the cold side outlet of the group A heat storage molten salt heat exchanger 4 is connected to the inlet of the group A molten salt hot tank 5, the hot side inlet of the group A heat storage molten salt heat exchanger 4 is connected to the outlet of the boiler superheater 21 through the high-pressure turbine inlet regulating valve 9, the hot side outlet of the group A heat storage molten salt heat exchanger 4 is connected to the outlet of the high-pressure turbine 22, and the outlet of the group A molten salt hot tank 5 passes through the group A exothermic molten salt regulating valve 6 and the group A exothermic molten salt pump 7 in sequence and is connected to the hot side inlet of the group A exothermic molten salt heat exchanger 8, the hot side outlet of the group A exothermic molten salt heat exchanger 8 is connected to the inlet of the group A molten salt cold tank 1, the cold side inlet of the group A exothermic molten salt heat exchanger 8 is connected to the cold side outlet of the high-temperature regenerator 24 through the boiler inlet regulating valve 10, and the cold side outlet of the group A exothermic molten salt heat exchanger 8 is connected to the inlet of the high-pressure turbine 22.

[0042] The outlet of the cold tank 11 of group B molten salt passes through the regulating valve 12 of group B thermal storage molten salt, the pump 13 of group B thermal storage molten salt and is connected to the cold side inlet of the heat storage molten salt heat exchanger 14 of group B in sequence. The cold side outlet of the heat storage molten salt heat exchanger 14 of group B is connected to the inlet of the hot tank 15 of group B molten salt. The hot side inlet of the heat storage molten salt heat exchanger 14 of group B is connected to the outlet of the boiler reheater 21 through the low-pressure turbine inlet regulating valve 19. The hot side outlet of the heat storage molten salt heat exchanger 14 of group B is connected to the outlet of the low-pressure turbine 23. The outlet of the B group molten salt hot tank 15 is connected to the hot side inlet of the B group molten salt heat exchanger 18 through the B group exothermic molten salt regulating valve 16 and the B group exothermic molten salt pump 17 in sequence, the hot side outlet of the B group molten salt heat exchanger 18 is connected to the inlet of the B group molten salt cold tank 11, the cold side inlet of the B group molten salt heat exchanger 18 is connected to the outlet of the high pressure turbine 22 through the high pressure turbine outlet regulating valve 20, and the cold side outlet of the B group molten salt heat exchanger 18 is connected to the inlet of the low pressure turbine 23. Among them, the working medium of the molten salt heat storage peak regulation system is molten salt.

[0043] The operation method of the molten salt heat storage peak-shaving system of the supercritical carbon dioxide power generation unit is as follows: when the grid dispatching load is reduced, the high-temperature working fluid extracted from the superheater outlet of the boiler 21 is depressurized by the high-pressure turbine inlet regulating valve 9 and then enters the group A heat storage molten salt heat exchanger 4 to release heat, and the working fluid after cooling and depressurization is mixed with the working fluid at the outlet of the high-pressure turbine 22. The low-temperature molten salt in the group A molten salt cold tank 1 is pressurized in the group A heat storage molten salt pump 3 by the group A heat storage molten salt regulating valve 2, and then is transported to the group A heat storage molten salt heat exchanger 4 to absorb heat and heat up, and then stored in In the A group molten salt hot tank 5; when the grid dispatching load is reduced, the high-temperature working fluid extracted from the reheater outlet of the boiler 21 is depressurized by the low-pressure turbine inlet regulating valve 19 and then enters the B group heat storage molten salt heat exchanger 14 to release heat, and the working fluid after cooling and depressurization is mixed with the working fluid at the outlet of the low-pressure turbine 23. The low-temperature molten salt in the B group molten salt cold tank 11 is pressurized in the B group heat storage molten salt pump 13 by the B group heat storage molten salt regulating valve 12, and then transported to the B group heat storage molten salt heat exchanger 14 to absorb heat and heat up, and then stored in the B group molten salt hot tank 15.

[0044] When the grid dispatching load increases, the high-temperature molten salt stored in the group A molten salt hot tank 5 is pressurized in the group A exothermic molten salt pump 7 through the group A exothermic molten salt regulating valve 6, and is transported to the group A exothermic molten salt heat exchanger 8 to release heat and cool down, and then stored in the group A molten salt cold tank 1. At the same time, the boiler inlet regulating valve 10 is opened to send the diverted part of the working fluid at the cold side outlet of the high-temperature regenerator 24 into the group A exothermic molten salt heat exchanger 8 to absorb heat and increase the temperature, and then mix with the working fluid at the inlet of the high-pressure turbine 22 to enter the high-pressure turbine 22 to do work; When the grid dispatching load increases, the high-temperature molten salt stored in the group B molten salt hot tank 15 is pressurized in the group B exothermic molten salt pump 17 through the group B exothermic molten salt regulating valve 16, and is transported to the group B exothermic molten salt heat exchanger 18 to release heat and cool down, and then stored in the group B molten salt cold tank 11. At the same time, the high-pressure turbine outlet regulating valve 20 is opened, and part of the high-pressure turbine outlet working fluid is diverted and sent to the group B exothermic molten salt heat exchanger 18 to absorb heat and rise in temperature, and then mixed with the low-pressure turbine 23 inlet working fluid to enter the low-pressure turbine 23 to do work.

[0045] In the supercritical carbon dioxide power generation system, the working fluid, after being pressurized by the main compressor 28, absorbs heat and heats up in the low-temperature reheater 25, the high-temperature reheater 24 and the superheater in the boiler 21, and then enters the high-pressure turbine 22 to partially expand and do work. The pressure and temperature of the partially expanded working fluid are reduced, and then the working fluid continues to absorb heat and heat up in the reheater of the boiler 21, and enters the low-pressure turbine 23 to completely expand and do work. The working fluid that has done work releases heat in the high-temperature reheater 24 and the low-temperature reheater 25 in turn. The working fluid after heat release is divided into two paths. One path is pressurized by the recompressor 26 and mixed with the working fluid at the cold side outlet of the low-temperature reheater 25, and the other path continues to release heat and cool in the precooler 27 before entering the main compressor 28 for pressurization. The working fluid thus forms a closed cycle.

[0046] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. The operation method of the molten salt heat storage peak regulation system of the supercritical carbon dioxide power generation unit is characterized in that: The supercritical carbon dioxide power generation unit molten salt heat storage peak-shaving system comprises a supercritical carbon dioxide cycle power generation system and two sets of molten salt heat storage peak-shaving systems; The supercritical carbon dioxide cycle power generation system comprises a boiler (21), a high-pressure turbine (22), a low-pressure turbine (23), a high-temperature regenerator (24), a low-temperature regenerator (25), a recompressor (26), a precooler (27) and a main compressor (28); the superheater outlet of the boiler (21) is connected to the inlet of the high-pressure turbine (22), the outlet of the high-pressure turbine (22) is connected to the inlet of the reheater of the boiler (21), and the outlet of the reheater of the boiler (21) is connected to the inlet of the low-pressure turbine (23); The outlet of the low-pressure turbine (23) is connected to the hot side of the high-temperature regenerator (24) and the low-temperature regenerator (25) in sequence. The hot side outlet of the low-temperature regenerator (25) is divided into two paths, one of which is connected to the inlet of the recompressor (26) and the other is connected to the hot side inlet of the precooler (27). The hot side outlet of the precooler (27) is connected to the inlet of the main compressor (28), the outlet of the main compressor (28) is connected to the low-temperature regenerator (25) and the cold side of the high-temperature regenerator (24) in sequence, the cold side outlet of the high-temperature regenerator (24) is connected to the superheater inlet of the boiler (21), and the outlet of the recompressor (26) is connected to the cold side outlet of the low-temperature regenerator (25); The working medium of the supercritical carbon dioxide cycle power generation system is supercritical carbon dioxide; The two groups of molten salt heat storage peak-shaving systems include group A and group B, which are respectively connected in sequence: a group A molten salt cold tank (1), a group A heat storage molten salt regulating valve (2), a group A heat storage molten salt pump (3), a group A heat storage molten salt heat exchanger (4), a group A molten salt hot tank (5), a group A heat release molten salt regulating valve (6), a group A heat release molten salt pump (7) and a group A heat release molten salt heat exchanger (8); and a group B molten salt cold tank (11), a group B heat storage molten salt regulating valve (12), a group B heat storage molten salt pump (13), a group B heat storage molten salt heat exchanger (14), a group B molten salt hot tank (15), a group B heat release molten salt regulating valve (16), a group B heat release molten salt pump (17) and a group B heat release molten salt heat exchanger (18); The outlet of the group A molten salt cold tank (1) is connected to the cold side inlet of the group A molten salt heat exchanger (4) through the group A thermal storage molten salt regulating valve (2) and the group A thermal storage molten salt pump (3) in sequence, and the cold side outlet of the group A thermal storage molten salt heat exchanger (4) is connected to the inlet of the group A molten salt hot tank (5); The outlet of the hot tank (5) of group A molten salt is connected to the hot side inlet of the heat release molten salt heat exchanger (8) of group A through the heat release molten salt regulating valve (6) of group A and the heat release molten salt pump (7) of group A in sequence, and the hot side outlet of the heat release molten salt heat exchanger (8) of group A is connected to the inlet of the cold tank (1) of group A molten salt; The outlet of the group B molten salt cold tank (11) is connected to the cold side inlet of the group B thermal storage molten salt heat exchanger (14) through the group B thermal storage molten salt regulating valve (12) and the group B thermal storage molten salt pump (13) in sequence, and the cold side outlet of the group B thermal storage molten salt heat exchanger (14) is connected to the inlet of the group B molten salt hot tank (15); The outlet of the hot tank (15) of group B molten salt is connected to the hot side inlet of the heat release molten salt heat exchanger (18) of group B through the heat release molten salt regulating valve (16) of group B and the heat release molten salt pump (17) of group B in sequence, and the hot side outlet of the heat release molten salt heat exchanger (18) of group B is connected to the inlet of the cold tank (11) of group B molten salt; The working medium of the two molten salt thermal storage peak regulation systems is molten salt; The operation method is as follows: after the working medium is pressurized by the main compressor (28), it absorbs heat in the low-temperature regenerator (25), the high-temperature regenerator (24) and the superheater in the boiler (21) in turn, and after the temperature is increased, it enters the high-pressure turbine (22) to partially expand and do work. After the work is done, the temperature and pressure of the working medium are reduced, and then it re-enters the reheater of the boiler (21) to continue absorbing heat and increasing the temperature, and enters the low-pressure turbine (23) to fully expand and do work. After the work is completed, the working medium enters the high-temperature regenerator (24) and the low-temperature regenerator (25) in turn to release heat. After releasing heat, the working medium is divided into two paths, one path is pressurized by the recompressor (26) and then merged into the cold side outlet of the low-temperature regenerator (25), and the other path is cooled and released by the precooler (27) and then enters the main compressor (28) for pressurization, thereby completing a closed cycle; When the grid dispatching load is reduced, the high-temperature working fluid extracted from the outlet of the superheater of the boiler (21) is depressurized by the high-pressure turbine inlet regulating valve (9) and then enters the group A heat storage molten salt heat exchanger (4) to release heat. The working fluid after cooling and depressurization is mixed with the working fluid at the outlet of the high-pressure turbine (22) and enters the reheater of the boiler (21) to absorb heat and increase the temperature. The high-temperature working fluid extracted from the outlet of the reheater of the boiler (21) is depressurized by the low-pressure turbine inlet regulating valve (19) and then enters the group B heat storage molten salt heat exchanger (14) to release heat. The working fluid after cooling and depressurization is mixed with the working fluid at the outlet of the low-pressure turbine (23) and then enters the high-temperature regenerator (24) to release heat and reduce the temperature. When the grid dispatching load is reduced, the group A heat storage molten salt regulating valve (2) and / or the group B heat storage molten salt regulating valve (12) are opened, and the low-temperature molten salt in the group A molten salt cold tank (1) is pressurized in the group A heat storage molten salt pump (3) through the group A heat storage molten salt regulating valve (2), and then transported to the group A heat storage molten salt heat exchanger (4) to absorb heat and increase temperature, and then stored in the group A molten salt hot tank (5); the low-temperature molten salt in the group B molten salt cold tank (11) is pressurized in the group B heat storage molten salt pump (13) through the group B heat storage molten salt regulating valve (12), and then transported to the group B heat storage molten salt heat exchanger (14) to absorb heat and increase temperature, and then stored in the group B molten salt hot tank (15); When the grid dispatching load increases, the exothermic molten salt regulating valve (6) of group A and / or the exothermic molten salt regulating valve (16) of group B are opened, and the high-temperature molten salt stored in the molten salt hot tank (5) of group A passes through the exothermic molten salt regulating valve (6) and is pressurized in the exothermic molten salt pump (7) of group A, and is transported to the exothermic molten salt heat exchanger (8) of group A to release heat and cool down, and is then stored in the molten salt cold tank (1) of group A; the high-temperature molten salt stored in the molten salt hot tank (15) of group B passes through the exothermic molten salt regulating valve (16) of group B to be pressurized in the exothermic molten salt pump (17) of group B, and is then transported to the exothermic molten salt heat exchanger (18) of group B to release heat and cool down, and is then stored in the molten salt cold tank (11) of group B; When the grid dispatching load increases, the boiler inlet regulating valve (10) is opened, and part of the outlet working fluid at the cold side of the high-temperature regenerator (24) is diverted and sent to the A group exothermic molten salt heat exchanger (8) to absorb heat and increase the temperature, and then mixed with the inlet working fluid of the high-pressure turbine (22) to enter the high-pressure turbine (22) to perform work; the high-pressure turbine outlet regulating valve (20) is opened, and part of the outlet working fluid of the high-pressure turbine is diverted and sent to the B group exothermic molten salt heat exchanger (18) to absorb heat and increase the temperature, and then mixed with the inlet working fluid of the low-pressure turbine (23) to enter the low-pressure turbine (23) to perform work.

2. The method for operating the molten salt heat storage peak-shaving system of a supercritical carbon dioxide power generation unit according to claim 1, characterized in that: The two groups of molten salt heat storage peak-shaving systems operate independently of each other. Both groups can be operated at the same time, or one of them can be operated alone. The specific operation mode depends on the grid dispatching load.

3. The operating method of the molten salt heat storage peak-shaving system of the supercritical carbon dioxide power generation unit according to claim 1 is characterized in that: The two groups of molten salt heat storage peak regulation systems further include a high-pressure turbine inlet regulating valve (9), a boiler inlet regulating valve (10), a low-pressure turbine inlet regulating valve (19), and a high-pressure turbine outlet regulating valve (20); The hot side inlet of the heat storage molten salt heat exchanger (4) of group A is connected to the superheater outlet of the boiler (21) through the high-pressure turbine inlet regulating valve (9), the hot side outlet of the heat storage molten salt heat exchanger (4) of group A is connected to the outlet of the high-pressure turbine (22), the cold side inlet of the heat release molten salt heat exchanger (8) of group A is connected to the cold side outlet of the high-temperature regenerator (24) through the boiler inlet regulating valve (10), and the cold side outlet of the heat release molten salt heat exchanger (8) of group A is connected to the inlet of the high-pressure turbine (22); The hot side inlet of the heat storage molten salt heat exchanger (14) of group B is connected to the reheat outlet of the boiler (21) through the low-pressure turbine inlet regulating valve (19), the hot side outlet of the heat storage molten salt heat exchanger (14) of group B is connected to the outlet of the low-pressure turbine (23), the cold side inlet of the heat release molten salt heat exchanger (18) of group B is connected to the outlet of the high-pressure turbine (22) through the high-pressure turbine outlet regulating valve (20), and the cold side outlet of the heat release molten salt heat exchanger (18) of group B is connected to the inlet of the low-pressure turbine (23).

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