Coal-fused salt energy storage coupling power generation system

Abstract

The utility model provides a fire coal-fused salt energy storage coupling power generation system, which solves the technical problems that the existing thermal power generation system mentioned in the background technology is insufficient in deep peak regulation and peak capacity and is difficult to fully and timely respond to the load demand of a power grid. The utility model discloses a fire coal-fused salt energy storage coupling power generation system which comprises a thermal power generating unit, the thermal power generating unit comprises a coal-fired boiler, a steam turbine generator unit and a water supply unit, the system further comprises a fused salt energy storage system, and the fused salt energy storage system comprises a fused salt flue gas heater, a fused salt storage unit and a steam generation unit. The fused salt storage unit is used for storing high-temperature fused salt and low-temperature fused salt; the fused salt flue gas heater is used for performing heat exchange on introduced low-temperature fused salt and flue gas from the coal-fired boiler and generating high-temperature fused salt, and the steam generation unit is used for performing heat exchange on shunted feed water and the high-temperature fused salt and generating superheated steam.

Description

Technical Field

[0001] The utility model relates to the technical field of thermal power generation, in particular to a coal-fired molten salt energy storage coupled power generation system. Background Art

[0002] Coal-fired power generation is a major part of China's power system, and coal-fired power generation units are excellent peak shaving power sources and base load power sources. However, with the increase in the installed capacity ratio of new energy sources such as photovoltaic and wind power, the intermittent, random, and volatile characteristics of wind and light have brought huge challenges to the safe and stable operation of the power system. Although coal-fired units still play an important role in the power balance of the power system, the demand for deep peak shaving and peak load of coal-fired power generation is increasing day by day, and the flexibility requirements are getting higher and higher. The problem of insufficient peak shaving and peak load capacity needs to be solved urgently. Limited by the characteristics of the boiler itself, its minimum operating load is restricted and difficult to drop below 30%. Facing the current complex grid demand, its peak load capacity is weak, the load increase speed is slow, it is difficult to meet the requirements of the new power system, and there will also be a large amount of abandoned electricity in the power generation of other energy sources such as new energy. Content of the Utility Model

[0003] Aiming at the deficiencies in the prior art, the utility model provides a coal-fired molten salt energy storage coupled power generation system, which solves the technical problems of insufficient deep peak shaving and peak load capacity of the existing thermal power generation system mentioned in the background art and is difficult to fully and timely respond to the grid load demand.

[0004] The technical purpose of the utility model is achieved through the following technical solutions:

[0005] A coal-fired and molten salt energy storage coupled power generation system, comprising a thermal power unit. The thermal power unit includes a coal-fired boiler, a steam turbine generator set, and a feed water unit. The coal-fired boiler is used to provide superheated steam to the steam turbine generator set, and the feed water unit is used to receive the steam from the steam turbine generator set, process it into feed water, and supply it to the coal-fired boiler. It is characterized in that it further includes a molten salt energy storage system. The molten salt energy storage system includes a molten salt flue gas heater, a molten salt storage unit, and a steam generation unit. The molten salt storage unit is respectively connected to the molten salt flue gas heater and the steam generation unit to form a molten salt circulation path. The high-temperature side of the molten salt flue gas heater is connected to the flue gas chamber of the coal-fired boiler, the low-temperature side of the molten salt flue gas heater is connected to the molten salt storage unit, the high-temperature side of the steam generation unit is connected to the molten salt storage unit, and the low-temperature side of the steam generation unit is connected to the feed water unit. The molten salt storage unit is used to store high-temperature molten salt and low-temperature molten salt. The molten salt flue gas heater is used to exchange heat between the introduced low-temperature molten salt and the flue gas from the coal-fired boiler and generate high-temperature molten salt. The steam generation unit is used to exchange heat between the diverted feed water and the high-temperature molten salt and generate superheated steam. The superheated steam generated by the steam generation unit is used to be supplied to the steam turbine generator set. The rated load capacity of the steam turbine generator set is W1, the rated load capacity of the coal-fired boiler is W2, and the rated load capacity of the molten salt energy storage system is W3, where W3=(W1 - W2)*n, n≥1.

[0006] As a preferred embodiment of the present invention, the flue gas outlet of the coal-fired boiler is connected to the high-temperature side flue gas inlet of the molten salt flue gas heater, the flue gas return port of the coal-fired boiler is connected to the high-temperature side flue gas outlet of the molten salt flue gas heater, the low-temperature molten salt outlet of the molten salt storage unit is connected to the low-temperature side molten salt inlet of the molten salt flue gas heater, and the high-temperature molten salt inlet of the molten salt storage unit is connected to the low-temperature side molten salt outlet of the molten salt flue gas heater.

[0007] As a preferred embodiment of the present invention, the molten salt energy storage system further includes a molten salt electric heater. The low-temperature side inlet of the molten salt flue gas heater and the molten salt inlet of the molten salt electric heater are respectively connected to the low-temperature molten salt outlet of the molten salt storage unit. The low-temperature side outlet of the molten salt flue gas heater and the molten salt outlet of the molten salt electric heater are respectively connected to the high-temperature molten salt inlet of the molten salt storage unit. The molten salt electric heater is used to electrically heat the introduced low-temperature molten salt to generate high-temperature molten salt.

[0008] As a preferred embodiment of the present invention, the steam generating unit includes a preheater, an evaporator and a superheater, whose high-temperature sides and low-temperature sides are connected in sequence, the high-temperature molten salt outlet of the molten salt storage unit is connected to the high-temperature side molten salt inlet of the superheater, the low-temperature molten salt inlet of the molten salt storage unit is connected to the low-temperature side molten salt outlet of the preheater, the diverter outlet of the water supply unit is connected to the low-temperature side water inlet of the preheater, and the low-temperature side steam outlet of the superheater is connected to the steam turbine generator set.

[0009] As a preferred embodiment of the present invention, the low-temperature side steam outlet of the superheater is also connected to a pipeline communicating with the heat user side and / or the high-temperature side of the feed water regenerator of the water supply unit.

[0010] As a preferred embodiment of the present invention, the superheated steam generated by the steam generation unit is also used to supply to the heat user side and / or the high temperature side of the water supply regenerator of the water supply unit.

[0011] As a preferred embodiment of the present invention, the water supply unit includes a condenser, a low-pressure regenerator, a deaerator and a high-pressure regenerator connected in sequence, the condenser is connected to the steam turbine generator set, and the high-pressure regenerator is connected to the coal-fired boiler.

[0012] As a preferred embodiment of the present invention, the deaerator is provided with a diversion outlet for conveying a portion of feed water to the steam generating unit.

[0013] As a preferred embodiment of the present invention, the molten salt storage unit includes a hot salt tank and a cold salt tank, the hot salt tank is provided with a high-temperature molten salt inlet and a high-temperature molten salt outlet, and the cold salt tank is provided with a low-temperature molten salt inlet and a low-temperature molten salt outlet.

[0014] As a preferred implementation mode of the present invention, the coupled power generation system is also equipped with a clean energy power generation system to jointly participate in the operation of the power grid.

[0015] Compared with the prior art, the utility model has the following beneficial effects:

[0016] 1. The power generation system of the present utility model adopts the form of coupling the thermal power unit with the molten salt energy storage system. On the one hand, it improves the peak shaving depth of the power generation system, enabling the thermal power unit to reach zero output at the lowest, and at the same time, it can store the heat energy of the coal-fired boiler in the molten salt energy storage system for later use. The configuration capacity ratio between the coal-fired boiler and the molten salt energy storage system can be flexibly adjusted according to the actual situation of the power grid to achieve a better peak shaving operation effect and ensure a faster load increase rate of the overall power generation system. On the other hand, it improves the load increase rate and peak capacity of the power generation system during peak electricity consumption. The heat energy stored in the molten salt energy storage system can be used at this time, and together with the thermal power unit, it drives the steam turbine generator set to generate electricity, effectively ensuring the safety and stability of the power grid operation.

[0017] 2. When cooperating with other main supporting energy sources, especially clean energy, when powered on, the existence of the power generation system of the present utility model can keep the thermal power unit itself connected to the grid with zero output and make way for other main supporting energy sources, especially clean energy, to access the grid when other main supporting energy sources, such as clean energy, meet the power grid load demand, further increasing the access proportion of other main supporting energy sources, especially clean energy.

[0018] 3. In the present utility model, the thermal power unit and the molten salt energy storage system share one steam turbine generator set, effectively reducing the cost of the entire system.

[0019] 4. Further, when the molten salt energy storage system in the present utility model is equipped with the molten salt electric heater, its electric energy can be obtained from the thermal power unit, clean energy supporting the system, or other external energy sources, helping to consume abandoned electricity, that is, flexibly selecting and setting clean energy and other external energy sources supporting the system and increasing their energy proportion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the operating state of an embodiment of the present utility model.

[0021] In the above-mentioned drawings: 1. Coal-fired boiler; 2. Steam turbine generator set; 3. Condenser; 4. Condensate pump; 5. Low-pressure regenerative heater; 6. Deaerator; 7. Feed water pump; 8. High-pressure regenerative heater; 9. Molten salt flue gas heater; 10. Molten salt electric heater; 11. Hot salt tank; 12. Cold salt tank; 13. Preheater; 14. Evaporator; 15. Superheater. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The technical solutions in the present utility model will be further described below with reference to the drawings and embodiments.

[0023] Such as Figure 1As shown, an embodiment of a coupled power generation system with coal combustion - molten salt energy storage includes a thermal power unit and a molten salt energy storage system. The overall energy configuration takes the form of photovoltaic, wind power, thermal power unit, and molten salt energy storage system as an example, and they jointly participate in the power grid operation.

[0024] The thermal power unit includes a coal - fired boiler 1, a steam turbine - generator set 2, and a feed water unit. The coal - fired boiler 1 is used to provide superheated steam to the steam turbine - generator set 2, and the feed water unit is used to receive the steam from the steam turbine - generator set 2 and process it into feed water and supply it to the coal - fired boiler 1. As Figure 1 shown, the feed water unit includes a condenser 3, a low - pressure regenerative heater 5, a deaerator 6, and a high - pressure regenerative heater 8 that are connected in sequence. The condenser 3 is connected to the steam turbine - generator set 2. A condensate pump 4 is also connected between the condenser 3 and the low - pressure regenerative heater 5. A feed water pump 7 is also connected between the deaerator 6 and the high - pressure regenerative heater 8. The high - pressure regenerative heater 8 is connected to the coal - fired boiler 1. The deaerator 6 is provided with a diversion outlet for delivering a part of the feed water to the steam generation unit.

[0025] The molten salt energy storage system includes a molten salt flue gas heater, a molten salt electric heater, a molten salt storage unit, and a steam generation unit. The molten salt storage unit is respectively connected to the molten salt flue gas heater, the molten salt electric heater, and the steam generation unit to form a molten salt circulation path. Among them, the molten salt flue gas heater and the molten salt electric heater are in a parallel arrangement form, that is, both are used to heat two parts of the molten salt from the molten salt storage unit respectively. The high - temperature side of the molten salt flue gas heater is connected to the flue gas chamber of the coal - fired boiler 1. The flue gas outlet of the coal - fired boiler 1 is connected to the high - temperature side flue gas inlet of the molten salt flue gas heater 9, and the flue gas return port of the coal - fired boiler 1 is connected to the high - temperature side flue gas outlet of the molten salt flue gas heater 9. The low - temperature side of the molten salt flue gas heater is connected to the molten salt storage unit. The high - temperature side of the steam generation unit is connected to the molten salt storage unit, and the low - temperature side of the steam generation unit is connected to the feed water unit; the molten salt storage unit is used to store high - temperature molten salt and low - temperature molten salt. The molten salt flue gas heater is used to make the introduced low - temperature molten salt absorb heat and become high - temperature molten salt. The steam generation unit is used to exchange heat between the diverted feed water and the high - temperature molten salt and generate superheated steam. The superheated steam generated by the steam generation unit is used to supply the steam turbine - generator set 2.

[0026] The molten salt storage unit includes a hot salt tank 11 and a cold salt tank 12. The hot salt tank 11 is provided with a high - temperature molten salt inlet and a high - temperature molten salt outlet. The cold salt tank 12 is provided with a low - temperature molten salt inlet and a low - temperature molten salt outlet. The high - temperature molten salt inlet of the hot salt tank 11 is respectively connected to the low - temperature side outlet of the molten salt flue gas heater 9 and the molten salt outlet of the molten salt electric heater 10. The high - temperature molten salt outlet of the hot salt tank 11 is connected to the high - temperature side molten salt inlet of the superheater 15. The low - temperature molten salt inlet of the cold salt tank 12 is connected to the low - temperature side molten salt outlet of the preheater 13. The low - temperature molten salt outlet of the cold salt tank 12 is connected to the low - temperature side inlet of the molten salt flue gas heater 9 and the molten salt inlet of the molten salt electric heater 10.

[0027] The steam generating unit includes a preheater 13, an evaporator 14, and a superheater 15, with their high-temperature sides and low-temperature sides connected in sequence. The low-temperature molten salt outlet of the preheater 13 is connected to the low-temperature molten salt inlet of the molten salt storage unit, and the high-temperature molten salt inlet of the superheater 15 is connected to the high-temperature molten salt outlet of the molten salt storage unit. The branched water outlet of the feed water unit is connected to the low-temperature side water inlet of the preheater 13, and the low-temperature side steam outlet of the superheater 15 is connected to the steam turbine generator set 2, which can cooperate with the coal-fired boiler 1 to drive the steam turbine generator set 2 to generate electricity during peak hours. The coal-fired boiler 1 is conventionally equipped with a superheated steam pipeline and a reheated steam pipeline. The high-temperature steam from the low-temperature side steam outlet of the superheater 15 can be selectively connected and merged into the superheated steam and / or reheated steam. Since the boiler feed water has certain temperature requirements, in this embodiment, the low-temperature side steam outlet of the superheater 15 can be connected to the high-temperature side of the feed water regenerator of the feed water unit. The aforementioned low-pressure regenerator 5 and high-pressure regenerator 8 both belong to the feed water regenerator. Generally, the low-temperature side steam outlet of the superheater 15 is connected to the high-temperature side inlet of the high-pressure regenerator 8 to preheat the boiler feed water. In other embodiments, the low-temperature side steam outlet of the superheater 15 can also be connected to the heat user side, that is, the superheated steam generated by the steam generating unit can be selectively supplied to the object according to actual needs, such as the heat user side or the high-temperature side of the feed water regenerator of the feed water unit.

[0028] The conventional working process of a thermal power unit is that the coal-fired boiler 1 generates superheated steam and sends it to the steam turbine generator set 2. The steam turbine generator set 2 starts generating electricity. After the superheated steam does work in the steam turbine generator set 2, it enters the feed water unit. The feed water unit processes the steam into feed water and then supplies the feed water back to the coal-fired boiler 1. With the increase in the proportion of new energy installed capacity, it is required that coal power reduce the load of the steam turbine generator set 2 when new energy such as photovoltaic and wind power generates a large amount of electricity and the electric energy is abundant. Traditional thermal power units are limited by the stable combustion and pollutant control requirements of the coal-fired boiler 1, and the minimum operating load is about 30%. The power generation system in this embodiment adopts the method of coupling a thermal power unit with a molten salt energy storage system. Taking the rated capacity W1 of the steam turbine generator set as the full capacity, the rated capacity W2 of the coal-fired boiler is configured as a part of the capacity, and the difference between the two is the other part of the capacity, that is, the rated capacity W3 of the molten salt energy storage system is configured as the other part of the capacity. That is, the rated capacity W1 of the steam turbine generator set = W2 + W3, so that compared with the traditional thermal power unit with a 100% boiler capacity configuration, the minimum power generation load of the coal-fired boiler 1 is further reduced. For example, when the rated capacity is configured according to W2 = 70%W1, calculated according to the minimum stable combustion load of the thermal power unit being 30%, compared with the traditional thermal power unit with a 100% boiler capacity configuration of W2 = W1, the actual output of the steam turbine generator set 2 is 70%W1 * 30% = 21%W1, reducing the load by 9 percentage points relatively.

[0029] At the same time, when the coal-fired boiler 1 is in operation, the energy generated by it can be stored in the molten salt through the flue gas and the molten salt flue gas heater 9. Therefore, when the coal-fired boiler 1 is stably burning at the lowest load, the boiler can only generate the steam required to maintain the minimum operating load of the steam turbine generator set, and the generator set can be connected to the grid with zero output. Still taking the rated capacity configuration of W2=70%W1 as an example, at this time, the actual output of the steam turbine generator set 2 driven by the coal-fired boiler 1 is 21% of the traditional thermal power unit. This part of energy can be stored in the high-temperature molten salt through the molten salt flue gas heater 9, and the steam turbine generator set does not output power to the power grid at this time. The molten salt flue gas heater 9 adopts a molten salt heating furnace to heat the molten salt with boiler flue gas, and the energy transfer is heat-heat transfer, and the energy utilization efficiency can reach more than 99%.

[0030] When the power demand of the power grid is met, for example, when the new energy installed capacity is the main force and its power generation has reached or exceeded the load demand of the power grid, the operating load of the coal-fired boiler is reduced to the minimum load for stable combustion, and the flue gas of the coal-fired boiler is drawn out at the same time, and the low-temperature molten salt is heated by the molten salt flue gas heater 9. The low-temperature molten salt is heated to become high-temperature molten salt and is passed into the molten salt storage unit for storage, which is the peak-shaving stage of the coupled power generation system; when the power demand of the power grid is large, for example, the output of new energy installed capacity such as photovoltaic and wind power is small or even does not generate electricity, resulting in a shortage of power in the power grid, it is necessary to increase the output load of the coal-fired boiler and put into use at the same time. The steam generated by both is incorporated into the steam turbine generator set, driving the steam turbine generator set to operate at 100% load, quickly increase the load, and reach the peak in a timely and sufficient manner, which is the peak stage of the coupled power generation system.

[0031] Since the load increase rate of the molten salt energy storage system is very fast, about more than 3 times that of the coal-fired boiler 1, the load increase rate and peak capacity of the overall system can be significantly improved. In addition, the configured capacity and ratio of the coal-fired boiler 1 and the molten salt energy storage system can be adjusted according to the actual situation of the power grid as needed to achieve a better peak shaving operation effect. For example, a larger proportion of the molten salt energy storage system can also be configured. The rated load capacity of the steam turbine generator set 2 is W1, the rated load capacity of the coal-fired boiler 1 is W2, and the rated load capacity of the molten salt energy storage system is W3, where W3=(W1 - W2)*n. As mentioned before, in this embodiment, n = 1, that is, the rated capacity W1 of the steam turbine generator set is equal to the sum of the rated load capacity of the coal-fired boiler 1 and the rated load capacity W3 of the molten salt energy storage system. In some other feasible embodiments, the value of n can be larger, that is, the molten salt energy storage system can be configured to reach a larger proportion of the surplus rated capacity. For example, W3=(W1 - W2)*1.1, to ensure a faster load increase rate of the overall combined power generation system. After the energy of the high-temperature molten salt is gradually released and cooperates with the gradual increase in the output of the coal-fired boiler 1 to make the overall load of the system approach the full load, the output of the molten salt energy storage system is gradually reduced, and the output of the coal-fired boiler is increased to the maximum load. In this way, it can not only effectively ensure the power supply support during the peak power consumption period of the power grid, but also respond to the power consumption demand of the power grid faster.

[0032] Specifically, taking clean energy and this combined power generation system as the energy configuration form of the power grid, the operation modes of different working conditions of this combined power generation system are as follows:

[0033] When the power generation of clean energy such as photovoltaic and wind power meets the load demand of the power grid, the thermal power unit operates in a stable combustion state with the coal-fired boiler 1, at the lowest load state. The molten salt flue gas heater 9 and the molten salt storage unit participate in the operation, and the steam generation unit does not participate in the operation. The superheated flue gas generated by the coal-fired boiler 1 is introduced into the high-temperature side of the molten salt flue gas heater 9, and the low-temperature molten salt in the cold salt tank 12 is introduced into the low-temperature side of the molten salt flue gas heater 9. The low-temperature molten salt introduced into the molten salt flue gas heater 9 absorbs the heat energy of the superheated flue gas and becomes high-temperature molten salt, which is then introduced into the hot salt tank 11 for storage. At this time, the steam generation amount of the coal-fired boiler 1 only meets the minimum steam amount requirement for the safe operation of the steam turbine generator set 2, and the steam turbine generator set 2 generates zero power and feeds it into the grid to make way for the clean energy to feed into the grid.

[0034] When the power generation from clean energy exceeds the grid load demand, the thermal power unit still operates at the minimum stable combustion load state of the coal-fired boiler 1. The molten salt flue gas heater and the molten salt storage unit participate in the operation, while the steam generation unit does not. The superheated flue gas generated by the coal-fired boiler 1 is introduced into the high-temperature side of the molten salt flue gas heater 9, and the low-temperature molten salt in the cold salt tank 12 is introduced into the low-temperature side of the molten salt flue gas heater 9. The low-temperature molten salt introduced into the molten salt flue gas heater 9 absorbs the thermal energy of the superheated flue gas and becomes high-temperature molten salt, which is then introduced into the hot salt tank 11 for storage. At this time, the steam generation amount of the coal-fired boiler 1 only meets the minimum steam amount requirement for the safe operation of the steam turbine generator set 2, and the steam turbine generator set 2 generates zero power and feeds it into the grid. At the same time, the molten salt electric heater 10 also participates in the operation. The excess power generated by clean energy such as photovoltaic and wind power is supplied to the molten salt electric heater 10. The molten salt electric heating furnace heats the low-temperature cold salt introduced from the cold salt tank into high-temperature molten salt and introduces it into the hot salt tank for storage. This part of the excess power generation is converted from the original abandoned power and is consumed by the molten salt electric heater 10 and becomes the stored molten salt thermal energy. Of course, according to the actual grid-connected energy configuration, the power source of the molten salt electric heater 10 can also be the original thermal power unit or other external energy sources. It is worth mentioning that according to the actual situation, the molten salt electric heater 10 can also be selected not to be set.

[0035] When the power generation from clean energy is insufficient to meet the grid load demand, the molten salt flue gas heater 9 and the molten salt electric heater 10 do not participate in the operation, while the molten salt storage unit and the steam generation unit participate. The high-temperature molten salt stored in the hot salt tank 11 is introduced into the high-temperature side of the superheater 15, and part of the feed water in the deaerator 6 is introduced into the low-temperature side of the preheater 13 (this part of the diverted feed water can also be selected to be extracted at other nodes of the feed water unit, and generally, it is preferably extracted from the passage nodes from the low-pressure regenerative heater 5 to the high-pressure regenerative heater 8). After the feed water passes through the low-temperature sides of the preheater 13, the evaporator 14, and the superheater 15 in sequence, it absorbs the thermal energy of the high-temperature molten salt on the high-temperature sides of the preheater 13, the evaporator 14, and the superheater 15 and becomes superheated steam, which is preferentially introduced into the steam turbine generator set 2 of the thermal power unit to drive the steam turbine generator set 2 to quickly increase the load. At the same time, the coal-fired boiler 1 increases the coal feeding amount and gradually increases the load, cooperating with the molten salt energy storage system to jointly drive the steam turbine generator set 2 until the power generation system meets the grid load demand. After that, as the load of the coal-fired boiler 1 rises to the maximum or is sufficient to meet the power consumption demand, the output of the molten salt energy storage system can be gradually reduced. The high-temperature molten salt passes through the high-temperature sides of the superheater 15, the evaporator 14, and the preheater 13 in sequence, and exchanges heat with the feed water on its low-temperature side to become low-temperature molten salt and is introduced into the cold salt tank 12 for storage.

[0036] In summary, for the power generation system of the thermal power unit coupled with the molten salt energy storage system in this embodiment, on the one hand, it can flexibly and effectively increase the peak shaving depth, and the thermal power unit can have zero output at the lowest; on the other hand, by using the molten salt energy storage system, it can flexibly and effectively increase the load increase rate and peak load capacity of the system during the peak electricity consumption period, ensuring the safety and stability of the power grid operation to the greatest extent, and can increase the grid connection ratio of other configured energy sources such as clean energy according to actual needs; the existence of the molten salt electric heater 10 can effectively absorb the abandoned electricity, further increasing the grid connection ratio and operation flexibility of other configured energy sources such as clean energy; the coal-fired boiler 1 of the power generation system itself and the molten salt energy storage system serve the common steam turbine generator set 2, and the molten salt flue gas heater 9 and the molten salt electric heater 10 share the molten salt energy storage system, effectively reducing the construction cost of the entire system. The rated capacity configuration ratio of the coal-fired boiler 1 and the molten salt energy storage system can be adjusted according to actual situations and conditions. When the rated capacity of the coal-fired boiler 1 is as low as possible, compared with the traditional thermal power unit, the minimum operating load can be further reduced, and the rated capacity of the molten salt energy storage system can be configured with a relatively more surplus ratio, which can further ensure a faster load increase rate of the coupled power generation system and help the thermal power unit reach the maximum output more safely and quickly.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A coupled power generation system of coal-fired power generation and molten salt energy storage, comprising a thermal power unit, wherein the thermal power unit comprises a coal-fired boiler (1), a steam turbine generator unit (2) and a water supply unit, wherein the coal-fired boiler (1) is used to provide superheated steam to the steam turbine generator unit (2), and the water supply unit is used to receive steam from the steam turbine generator unit (2) and process it into feed water and supply it to the coal-fired boiler (1), characterized in that: The invention also includes a molten salt energy storage system, which includes a molten salt flue gas heater (9), a molten salt storage unit and a steam generating unit. The molten salt storage unit is respectively connected to the molten salt flue gas heater (9) and the steam generating unit to form a molten salt circulation passage; the high temperature side of the molten salt flue gas heater (9) is connected to the flue gas chamber of the coal-fired boiler (1), the low temperature side of the molten salt flue gas heater (9) is connected to the molten salt storage unit, the high temperature side of the steam generating unit is connected to the molten salt storage unit, and the low temperature side of the steam generating unit is connected to the water supply unit; the molten salt storage The unit is used to store high-temperature molten salt and low-temperature molten salt, the molten salt flue gas heater (9) is used to exchange heat between the introduced low-temperature molten salt and the flue gas from the coal-fired boiler (1) to generate high-temperature molten salt, the steam generating unit is used to exchange heat between the diverted feed water and the high-temperature molten salt to generate superheated steam, and the superheated steam generated by the steam generating unit is used to supply the steam turbine generator set (2); the rated load capacity of the steam turbine generator set is W1, the rated load capacity of the coal-fired boiler is W2, and the rated load capacity of the molten salt energy storage system is W3, wherein W3 = (W1-W2)*n, n≥1.

2. A coal-fired-molten salt energy storage coupled power generation system according to claim 1, characterized in that: The flue gas outlet of the coal-fired boiler (1) is connected to the high-temperature side flue gas inlet of the molten salt flue gas heater (9), the flue gas return port of the coal-fired boiler (1) is connected to the high-temperature side flue gas outlet of the molten salt flue gas heater (9), the low-temperature molten salt outlet of the molten salt storage unit is connected to the low-temperature side molten salt inlet of the molten salt flue gas heater (9), and the high-temperature molten salt inlet of the molten salt storage unit is connected to the low-temperature side molten salt outlet of the molten salt flue gas heater (9).

3. A coal-fired-molten salt energy storage coupled power generation system according to claim 1, characterized in that: The molten salt energy storage system also includes a molten salt electric heater (10); the low-temperature side inlet of the molten salt flue gas heater (9) and the molten salt inlet of the molten salt electric heater (10) are respectively connected to the low-temperature molten salt outlet of the molten salt storage unit; the low-temperature side outlet of the molten salt flue gas heater (9) and the molten salt outlet of the molten salt electric heater (10) are respectively connected to the high-temperature molten salt inlet of the molten salt storage unit; the molten salt electric heater (10) is used to electrically heat the introduced low-temperature molten salt to generate high-temperature molten salt.

4. A coal-fired-molten salt energy storage coupled power generation system according to claim 1, characterized in that: The steam generating unit comprises a preheater (13), an evaporator (14) and a superheater (15), the high temperature side and the low temperature side of which are connected in sequence; the high temperature molten salt outlet of the molten salt storage unit is connected to the high temperature side molten salt inlet of the superheater (15); the low temperature molten salt inlet of the molten salt storage unit is connected to the low temperature side molten salt outlet of the preheater (13); the diverted water outlet of the water supply unit is connected to the low temperature side water inlet of the preheater (13); and the low temperature side steam outlet of the superheater (15) is connected to the steam turbine generator set.

5. A coal-fired-molten salt energy storage coupled power generation system according to claim 4, characterized in that: The low-temperature side steam outlet of the superheater (15) is also connected to a pipeline communicating with the heat user side and / or the high-temperature side of the water supply regenerator of the water supply unit.

6. A coal-fired-molten salt energy storage coupled power generation system according to claim 1, characterized in that: The superheated steam generated by the steam generation unit is also used to be supplied to the heat user side and / or the high temperature side of the regenerator of the water supply unit.

7. A coal-fired-molten salt energy storage coupled power generation system according to claim 1, characterized in that: The water supply unit comprises a condenser (3), a low-pressure regenerator (5), a deaerator (6) and a high-pressure regenerator (8) which are connected in sequence, the condenser (3) being connected to the steam turbine generator set (2), and the high-pressure regenerator (8) being connected to the coal-fired boiler (1).

8. A coal-fired-molten salt energy storage coupled power generation system according to claim 7, characterized in that: The deaerator (6) is provided with a split water outlet for conveying a portion of feed water to the steam generating unit.

9. A coal-fired-molten salt energy storage coupled power generation system according to claim 1, characterized in that: The molten salt storage unit comprises a hot salt tank (11) and a cold salt tank (12), wherein the hot salt tank (11) is provided with a high-temperature molten salt inlet and a high-temperature molten salt outlet, and the cold salt tank (12) is provided with a low-temperature molten salt inlet and a low-temperature molten salt outlet.

10. A coal-fired-molten salt energy storage coupled power generation system according to any one of claims 1 to 9, characterized in that: The coupled power generation system is also equipped with a clean energy power generation system to jointly participate in the operation of the power grid.

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