Constant-pressure heat storage system of compressed air energy storage power station

Abstract

The utility model discloses a compressed air energy storage power station constant pressure heat storage system which comprises a heat storage module, a circulation heat exchange module, a buffer water supplementing module and a nitrogen filling module, the heat storage module comprises a plurality of heat storage tanks, the heat storage tanks are all communicated with the nitrogen filling module, the circulation heat exchange module comprises a heat exchanger, and the heat exchanger is communicated with the buffer water supplementing module. A circulating pipe a and a circulating pipe b are arranged at two ports of a channel on one side of the heat exchanger respectively and are communicated with the heat storage tank in an opening and closing mode, the buffer water supplementing module comprises a buffer tank, a water supplementing pipe and a water returning pipe which are communicated with the buffer tank are arranged on the buffer tank, and the water supplementing pipe and the water returning pipe are communicated with the heat storage tank in an opening and closing mode. Compared with the prior art, on the premise that no heat loss exists, system pressure fluctuation can be effectively restrained, resource waste caused by loss of constant-pressure media (such as nitrogen) can be avoided, and popularization and application of the high-heat energy storage technology are greatly promoted.

Description

Technical Field

[0001] The utility model relates to the technical field of thermal energy storage, in particular to a constant-pressure thermal storage system of a compressed air energy storage power station. Background Art

[0002] More than half of the world's final energy consumption is thermal energy. Heat storage technology has the advantages of large energy storage capacity, long storage cycle, and low cost. The cost of heat storage can be 1 / 10 of the cost of electricity storage or even lower. Compared with other energy storage technologies, heat storage is more suitable for large-scale energy storage needs and can become an important driving force for increasing the penetration rate of renewable energy in energy systems. At present, conventional large-scale heat storage technology using water as a heat storage medium changes its volume when water absorbs heat and heats up and releases heat and cools down. The volume change of the heat storage medium will cause pressure fluctuations in the system, which will have an adverse effect on the heat storage and heat release stability of the system and the pressure fatigue of the container, and will reduce the system's heat storage and heat release efficiency and the service life of the pressure vessel, as well as the serious loss and waste of constant pressure media (such as nitrogen). These problems seriously restrict the promotion and application of thermal energy storage technology. Summary of the invention

[0003] The purpose of the utility model is to solve the problems in the prior art and to propose a constant-pressure heat storage system for a compressed air energy storage power station, which can effectively suppress system pressure fluctuations without heat loss and avoid waste of resources caused by loss of constant-pressure medium (such as nitrogen), which greatly promotes the promotion and application of high-heat energy storage technology.

[0004] To achieve the above-mentioned purpose, the utility model proposes a constant-pressure heat storage system for a compressed air energy storage power station, comprising a heat storage module, a circulating heat exchange module, a cache water replenishment module and a nitrogen filling module, wherein the heat storage module comprises a plurality of heat storage tanks, and the heat storage tanks are all connected to the nitrogen filling module, the circulating heat exchange module comprises a heat exchanger, and two ports of a side channel of the heat exchanger are respectively provided with a circulation pipe a and a circulation pipe b, and the circulation pipe a and the circulation pipe b are both openly and closedly connected to the heat storage tank, the cache water replenishment module comprises a cache tank, and the cache tank is provided with a water replenishment pipe and a return water pipe connected thereto, and the water replenishment pipe and the return water pipe are both openly and closedly connected to the heat storage tank.

[0005] Preferably, the circulating heat exchange module also includes flange port a, flange port b, flange port c and flange port d, and flange port a and flange port b are both connected to one port of the channel on the other side of the heat exchanger through valve j, and flange port c and flange port d are both connected to the other port of the channel on the other side of the heat exchanger through valve j.

[0006] Preferably, the nitrogen filling module comprises a nitrogen filling pipe, the nitrogen filling pipe is provided with a nitrogen filling port, and the nitrogen filling pipe is connected to each heat storage tank via a valve h.

[0007] Preferably, the cache tank is connected to the softened water supply pipe through valve i.

[0008] Preferably, a water supply drive pump group and a valve k are provided on the water supply pipe in sequence, the water supply pipe in front of the valve k is connected to each heat storage tank through a valve L, and a valve g is provided on the return pipe, and the return pipe in front of the valve g is connected to each heat storage tank through a valve e.

[0009] Preferably, the water replenishment drive pump group includes two water replenishment pumps arranged in parallel, and both ends of the water replenishment pumps are provided with stop valves a.

[0010] Preferably, a circulation drive pump group is provided on the circulation pipe a, the circulation pipe a behind the circulation drive pump group is connected to each heat storage tank through a valve a, a valve b is provided on the circulation pipe a between two adjacent valves a, the circulation pipe b is connected to each heat storage tank through a valve c, and a valve d is provided on the circulation pipe b between two adjacent valves c.

[0011] Preferably, the circulation drive pump group includes two circulating water pumps arranged in parallel, and both ends of the circulating water pumps are provided with stop valves b.

[0012] Preferably, the heat storage tank is provided with a pressure transmitter.

[0013] Preferably, the valves are all electric valves.

[0014] Beneficial effects of the utility model: The utility model can actively stabilize the system pressure by setting up a cache water replenishment module, and release a part of the volume of water into the cache tank during the heat storage stage, and the volume of the released water is consistent with the volume increase after the system heat storage and heating. In the heat release stage, a part of the volume of water is replenished from the cache tank to the low-temperature water ball tank, and the volume of the replenished water is consistent with the volume decrease after the system heat release and cooling. The water release and replenishment rates are adjustable, which is fully adapted to the volume change rate during the heat storage and release process. Compared with the existing technology, it can effectively suppress system pressure fluctuations without heat loss, and can avoid the waste of constant pressure medium (such as nitrogen) causing waste of resources, which greatly promotes the promotion and application of high thermal energy storage technology.

[0015] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The utility model is a structural schematic diagram of a constant pressure heat storage system of a compressed air energy storage power station.

[0017] In the figure: 1-heat storage module, 2-circulation heat exchange module, 3-buffer water replenishment module, 4-nitrogen filling module, 11-heat storage tank, 12-pressure transmitter, 21-heat exchanger, 22-circulation pipe a, 23-circulation pipe b, 24-circulation drive pump group, 25-valve c, 26-valve d, 27-flange a, 28-flange b, 29-flange c, 210-flange d, 211-valve j , 212-valve a, 213-valve b, 31-buffer tank, 32-water supply pipe, 33-valve e, 34-return pipe, 35-valve g, 36-valve i, 37-valve k, 38-water supply drive pump group, 39-valve L, 41-nitrogen filling pipe, 42-nitrogen filling port, 43-valve h, 381-water supply pump, 382-stop valve a, 241-circulating water pump, 242-stop valve b. DETAILED DESCRIPTION

[0018] See also Figure 1The utility model discloses a constant pressure heat storage system for a compressed air energy storage power station, comprising a heat storage module 1, a circulating heat exchange module 2, a cache water replenishment module 3 and a nitrogen filling module 4, wherein the heat storage module 1 comprises a plurality of heat storage tanks 11, and the heat storage tanks 11 are all connected to the nitrogen filling module 4, the circulating heat exchange module 2 comprises a heat exchanger 21, and two ports of a side channel of the heat exchanger 21 are respectively provided with a circulating pipe a22 and a circulating pipe b23, and the circulating pipe a22 and the circulating pipe b23 are both connected to the heat storage tank 11 in an open-closed manner, the cache water replenishment module 3 comprises a cache tank 31, and the cache tank 31 is provided with a water replenishment pipe 34 and a return pipe 34 connected thereto. 2, the water supply pipe 34 and the return pipe 32 are both in open and closed communication with the heat storage tank 11, the circulating heat exchange module 2 also includes a flange port a27, a flange port b28, a flange port c29 and a flange port d210, the flange port a27 and the flange port b28 are both in communication with one port of the other side channel of the heat exchanger 21 through a valve j211, the flange port c29 and the flange port d210 are both in communication with the other port of the other side channel of the heat exchanger 21 through a valve j211, the nitrogen filling module 4 includes a nitrogen filling pipe 41, the nitrogen filling pipe 41 is provided with a nitrogen filling port 42, and the nitrogen filling pipe 41 is connected to each heat storage tank 11. The buffer tank 31 is connected to the softened water supply pipe through the valve h43, the water supply pipe 34 is provided with a water supply drive pump group 38 and a valve k37 in sequence, the water supply pipe 34 in front of the valve k37 is connected to each heat storage tank 11 through the valve L39, the return pipe 32 is provided with a valve g35, the return pipe 32 in front of the valve g35 is connected to each heat storage tank 11 through the valve e33, the water supply drive pump group 38 includes two water supply pumps 381 arranged in parallel, both ends of the water supply pump 381 are provided with a stop valve a382, and the circulation pipe a22 is provided with a circulation drive The pump group 24, the circulation pipe a22 behind the circulation driving pump group 24 is connected to each heat storage tank 11 through a valve a212, and the circulation pipe a22 between two adjacent valves a212 is provided with a valve b213, the circulation pipe b23 is connected to each heat storage tank 11 through a valve c25, and the circulation pipe b23 between two adjacent valves c25 is provided with a valve d26, the circulation driving pump group 24 includes two circulating water pumps 241 arranged in parallel, both ends of the circulating water pump 241 are provided with a stop valve b242, the heat storage tank 11 is provided with a pressure transmitter 12, and the valves are all electric valves.

[0019] Working process of this utility model:

[0020] The utility model discloses a compressed air energy storage power station constant pressure heat storage system. During operation, the number of heat storage tanks 11 is four ( Figure 1 For medium spherical tanks A, B, C, D), the number of valves a212 is four ( Figure 1M13, M15, M17, M19), the number of valve b213 is three ( Figure 1 M21, M23, M25), the number of valve c25 is four ( Figure 1 M14, M16, M18, M20), the number of valves d26 is three ( Figure 1 M22, M24, M26), the number of valves e33 is four ( Figure 1 M5, M6, M7, M8), the number of valves h43 is four ( Figure 1 M1, M2, M3, M4), the number of valves j211 is four ( Figure 1 M32, M33, M34, M35); the number of valves k37 is four ( Figure 1 (M9, M10, M11, M12).

[0021] In the system startup phase, valve M1 is opened, nitrogen is first delivered to spherical tank A in heat storage module 1 through nitrogen filling module 4 and reaches the set pressure, then M1 is closed, a water supply pump 381 is started, valve L39 is opened, valves M6, M7, and M8 are opened in sequence, water is delivered to spherical tanks B, C, and D in sequence through buffer water supply module 3, and the set liquid levels are reached respectively and the corresponding valves M6, M7, and M8 are closed, then valve L39 is closed and the corresponding water supply pump 381 is stopped. At this time, the system completes the heat storage preparation.

[0022] In the heat storage stage of the system, valves M33 and M35 are opened, and the external heat source enters the system through the flange port b28 of the heat exchanger 21 in the circulating heat exchange module, and exits the system through the flange port c29 of the heat exchanger 21 after heat exchange. Start a circulating water pump 241 in the circulating heat exchange module and open the related stop valve b242, open valves M1, M2, M14, M15, and M21, and let the water in the spherical tank B pass through valves M15, M21 and the corresponding pipe section of the circulation pipe a22 from the bottom, and the high-temperature water after heat exchange enters the spherical tank A from the bottom through the corresponding pipe section of the circulation pipe b23 and M14. The nitrogen in the spherical tank A slowly enters the spherical tank B through valves M1, M2 and the corresponding pipe section of the nitrogen filling pipe 41 as the liquid level of the high-temperature water enters. In the continuous process, the cold water level in the spherical tank B slowly decreases, and the high-temperature water level in the spherical tank A slowly rises. When the cold water level in spherical tank B drops to the set value, spherical tank A stores hot water to complete heat storage, and spherical tank B stores nitrogen. Close valve g35 and valves M1, M2, M14, M15, and M21. During the heat storage process, the water expands after heating up, and the volume increases, causing the pressure in spherical tank A to increase. When the pressure transmitter 12 installed on spherical tank A detects the pressure increase, valve g35 and valve M6 are opened. Under the action of its internal pressure, the water retained in spherical tank B enters the buffer tank 31 through valve M6, valve g35 and the corresponding section of the return pipe 32, releasing its internal volume to stabilize the system pressure;

[0023] Open valves M2, M3, M17, M16, M21, M22, and M23, and let the cold water in spherical tank C pass through valves M17, M23, M21 and the corresponding pipe section of circulation pipe a22 from the bottom. The high-temperature water after heat exchange enters spherical tank B from the bottom through valves M22 and M16 of the corresponding pipe section of circulation pipe b23. The nitrogen in spherical tank B slowly enters spherical tank C through valves M2, M3 and the corresponding pipe section of nitrogen filling pipe 41 as the liquid level of high-temperature water enters. In the continuous process, the cold water level of spherical tank C slowly decreases, and the high-temperature water level of spherical tank B slowly increases. When the cold water level of spherical tank C drops to the set value, spherical tank B stores hot water to complete heat storage, and spherical tank C stores nitrogen, valves M2, M3, M17, M16, M21, M22, and M23. During the heat storage process, the water expands after heating up, and the volume increases, causing the pressure in the spherical tank B to increase. When the pressure transmitter 12 installed on the spherical tank B detects the pressure increase, the valve g35 and the valve M7 are opened. Under the action of the internal pressure, the water retained in the spherical tank C enters the buffer tank 31 through the valve M7, the valve g35 and the corresponding section of the return pipe 32, and releases its internal volume to stabilize the system pressure.

[0024] The switching is carried out in this way, and the cold water in the spherical tank D is transported to the circulating heat exchange module, and after heat exchange with the external heat source to become high-temperature water, it is transported to the spherical tank C for storage, and the nitrogen in the spherical tank C is transported to the spherical tank D. At this time, the spherical tanks A, B, and C in the heat storage module store hot water, and the spherical tank D stores nitrogen, and the heat storage stage of the system ends. In this process, part of the water is transported to the cache tank 31, and the volume of water transported to the cache tank 31 during the heat storage process is consistent with the volume increased during the system from low-temperature water to high-temperature water and low-temperature nitrogen to high-temperature nitrogen during the heat storage process.

[0025] In the heat release stage of the system, valves M32 and M34 are opened, and the external heat source enters the system through flange port a27 of heat exchanger 21, and exits the system through flange port d210 after heating. A circulating water pump 241 in the circulating heat exchange module is started, and valves M3, M4, M17, M21, M22, M23, M24, M26, and M20 are opened, and the heat release of spherical tank C is switched to the heat exchanger 21 from the bottom through valves M17, M23, and M21 and the corresponding pipe section of the circulation pipe a22, and heat exchange with the external heat source is completed in the heat exchanger 21. The low-temperature water after heat exchange enters spherical tank D from the bottom through valves M22, M24, M26, and M20 and the corresponding pipe section of the circulation pipe b23. The nitrogen in spherical tank D slowly enters spherical tank C through valves M4, M3 and the corresponding pipe section of nitrogen filling pipe 41 as the liquid level of low-temperature water enters. As the volume of water decreases during cooling, the pressure in the spherical tank D decreases. When the pressure transmitter 21 on the spherical tank D detects that the pressure in the spherical tank D decreases, the valves L39 and M12 are opened to start a water supply pump 381 and open the relevant stop valve a382, and the water in the buffer tank 31 is transported to the spherical tank D through the valves L39, M12 and the corresponding pipe sections of the water supply pipe 34. The volume reduction of water and nitrogen after cooling in the heat release process of the adaptation system spherical tank C is adjusted by the regulating valve b6 on the input end of the valve L39 to stabilize the system pressure. In the continuous process, the hot water level of the spherical tank C slowly decreases, and the low-temperature water level of the spherical tank D slowly increases. When the hot water level of the spherical tank C drops to the set value, the spherical tank C completes the heat release and stores nitrogen, and the spherical tank D stores cold water. Close valves M3, M4, M8, M17, M21, M22, M23, M24, M26, and M20.

[0026] Open valves M2, M3, M15, M18, M21, M22, and M24, switch to spherical tank B to release heat, and transport the high-temperature water in spherical tank B from the bottom through valves M15, M21, and the corresponding pipe section of the circulation pipe a22 to the heat exchanger 21, and complete heat exchange with the external heat source in the heat exchanger 21. The low-temperature water after heat exchange enters spherical tank C from the bottom through valves M22, M24, M18, and the corresponding pipe section of the circulation pipe b23. The nitrogen in spherical tank C slowly enters spherical tank B through valves M2, M3, and the corresponding pipe section of the nitrogen filling pipe 41 as the liquid level of the low-temperature water enters. When the pressure transmitter 21 on the spherical tank C detects that the pressure in the spherical tank C is reduced, the valves L39 and M11 are opened, a water supply pump 381 is started, and the relevant stop valve a382 is opened, and the water in the buffer tank 31 is transported to the spherical tank C through the valves L39, M11 and the corresponding pipe sections of the water supply pipe 34. The volume reduction of the water and nitrogen after cooling during the heat release process of the adaptation system spherical tank B is adjusted by the regulating valve b6 on the input end of the valve L39 to stabilize the system pressure. In the continuous process, the hot water level of the spherical tank B slowly decreases, and the low-temperature water level of the spherical tank C slowly increases. When the hot water level of the spherical tank B drops to the set value, the spherical tank B completes the heat release and stores nitrogen, and the spherical tank C stores cold water. Close valves M2, M3, M15, M18, M21, M22, and M24.

[0027] The switching is carried out in this way, and the cold water in the spherical tank A is transported to the circulating heat exchange module, and after heat exchange with the external heat source to become low-temperature water, it is transported to the spherical tank B for storage, and the nitrogen in the spherical tank B is transported to the spherical tank A. At this time, the spherical tanks B, C, and D in the heat storage module store low-temperature water, and the spherical tank A stores nitrogen, and the heat release stage ends. In this process, part of the water is transported to the low-temperature water spherical tank in sequence by the buffer water replenishment module. The volume of water transported to the low-temperature water spherical tank during the heat release process is consistent with the volume reduction in the process of the system changing from high-temperature water to low-temperature water and high-temperature nitrogen to low-temperature nitrogen during the heat release process.

[0028] The thermal energy storage system of the utility model uses nitrogen as an isolation and insulation medium to effectively isolate high-temperature water from low-temperature water, and prevent thermal short circuit. At the same time, the system pressure is increased to ensure that high-temperature water does not flash vaporize, and the heat storage temperature can be increased to 300°C. At the same time, it can ensure that the pressure in the tank remains constant during the heat storage and heat release process. Compared with conventional heat storage systems, the utility model can greatly improve the energy storage density, effectively reduce the volume of the storage tank, increase the service life, and reduce the one-time investment; it is not limited to use in compressed air power stations, but can also be used in other heat storage fields, such as new energy consumption, solar thermal power generation heat storage, off-peak electricity heat storage and other fields;

[0029] Compared with the conventional heat storage system where cold water tanks and hot water tanks need to be paired separately, the spherical tank of the thermal energy storage system of the utility model can be used as both a high-temperature storage tank and a low-temperature storage tank, which can greatly reduce the number of storage tanks, and the thermal energy storage density and capacity are extremely large. (The energy storage capacity of the conventional system is n / 2; the energy storage capacity of the high energy storage density thermal storage system of the utility model is n-1n: the number of storage tanks), which greatly reduces the one-time investment and floor space.

[0030] The utility model is provided with a buffer water replenishment module, which can stabilize the system pressure. In the heat storage stage, part of the volume of water is released into the buffer tank by the system's internal pressure. In the heat release stage, part of the volume of water is replenished from the buffer tank to the low-temperature water ball tank, thereby stabilizing the system pressure.

[0031] The heat exchanger and the pump in the circulating heat exchange module in the thermal energy storage system of the utility model can realize the heat storage function and the heat release function through valve switching, and there is no need to set up a heat storage heat exchanger and a heat release heat exchanger separately.

[0032] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention falls within the protection scope of the present invention.

Claims

1. A constant pressure heat storage system for a compressed air energy storage power station, characterized in that: The invention comprises a heat storage module (1), a circulating heat exchange module (2), a buffer water replenishment module (3) and a nitrogen filling module (4), wherein the heat storage module (1) comprises a plurality of heat storage tanks (11), and the heat storage tanks (11) are all connected to the nitrogen filling module (4); the circulating heat exchange module (2) comprises a heat exchanger (21), and two ports of a side channel of the heat exchanger (21) are respectively provided with a circulating pipe a (22) and a circulating pipe b (23), and the circulating pipe a (22) and the circulating pipe b (23) are both connected to the heat storage tank (11) in an open-closed manner; the buffer water replenishment module (3) comprises a buffer tank (31), and the buffer tank (31) is provided with a water replenishment pipe (34) and a water return pipe (32) connected thereto, and the water replenishment pipe (34) and the water return pipe (32) are both connected to the heat storage tank (11) in an open-closed manner.

2. A compressed air energy storage power station constant pressure heat storage system according to claim 1, characterized in that: The circulating heat exchange module (2) further comprises a flange port a (27), a flange port b (28), a flange port c (29) and a flange port d (210); the flange port a (27) and the flange port b (28) are both connected to one port of the channel on the other side of the heat exchanger (21) through a valve j (211); and the flange port c (29) and the flange port d (210) are both connected to the other port of the channel on the other side of the heat exchanger (21) through the valve j (211).

3. A compressed air energy storage power station constant pressure heat storage system according to claim 1, characterized in that: The nitrogen filling module (4) comprises a nitrogen filling pipe (41), the nitrogen filling pipe (41) is provided with a nitrogen filling port (42), and the nitrogen filling pipe (41) is connected to each heat storage tank (11) via a valve h (43).

4. A compressed air energy storage power station constant pressure heat storage system according to claim 1, characterized in that: The buffer tank (31) is connected to the softened water supply pipe via a valve i (36).

5. A compressed air energy storage power station constant pressure heat storage system according to claim 1, characterized in that: The water supply pipe (34) is provided with a water supply drive pump group (38) and a valve k (37) in sequence. The water supply pipe (34) in front of the valve k (37) is connected to each heat storage tank (11) via a valve L (39). The return pipe (32) is provided with a valve g (35). The return pipe (32) in front of the valve g (35) is connected to each heat storage tank (11) via a valve e (33).

6. A compressed air energy storage power station constant pressure heat storage system as claimed in claim 5, characterized in that: The water replenishment drive pump group (38) comprises two water replenishment pumps (381) arranged in parallel, and both ends of the water replenishment pumps (381) are provided with stop valves a (382).

7. A compressed air energy storage power station constant pressure heat storage system according to claim 1, characterized in that: The circulation pipe a (22) is provided with a circulation drive pump group (24); the circulation pipe a (22) behind the circulation drive pump group (24) is connected to each heat storage tank (11) via a valve a (212); a valve b (213) is provided on the circulation pipe a (22) between two adjacent valves a (212); the circulation pipe b (23) is connected to each heat storage tank (11) via a valve c (25); a valve d (26) is provided on the circulation pipe b (23) between two adjacent valves c (25).

8. A compressed air energy storage power station constant pressure heat storage system according to claim 7, characterized in that: The circulating drive pump group (24) comprises two circulating water pumps (241) arranged in parallel, and both ends of the circulating water pumps (241) are provided with stop valves b (242).

9. A compressed air energy storage power station constant pressure heat storage system according to claim 1, characterized in that: The heat storage tank (11) is provided with a pressure transmitter (12).

10. A compressed air energy storage power station constant pressure heat storage system according to any one of claims 2 to 8, characterized in that: The valves are all electric valves.

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