A compressed air energy storage system with multi-stage waste heat utilization

Abstract

The present invention provides a compressed air energy storage system with multi-stage waste heat utilization, which belongs to the field of electric energy storage technology. A multi-stage waste heat utilization system is formed by utilizing waste heat from the operation of other systems in the station, waste heat from the exhaust of the compressed air energy storage system, and high-temperature heat storage of the heat storage device during the compression process. The expansion power generation system driven by the multi-stage waste heat utilization system is operated in parallel with the original expansion power generation system, and the newly added one has fewer expansion stages or a smaller expansion ratio, and a lower rated power generation power. The gas storage system of the compressed air energy storage system can realize that the parallel expansion power generation systems can operate simultaneously. The inlet air of the newly added expansion power generation system preferentially utilizes the remaining high-pressure air that cannot drive the original expansion power generation system. The high-pressure air is heated in sequence by the waste heat from the exhaust of the original expansion system, the waste heat from the operation of other systems, and the high-temperature heat storage device and sent to the expansion system. The waste heat of the compressed air energy storage system and the waste heat from the operation of other systems can be effectively utilized to improve the energy conversion efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of electric energy storage, and in particular to a compressed air energy storage system for multi-stage waste heat utilization. Background Art

[0002] As a typical energy storage system, compressed air energy storage system has attracted widespread attention in recent years due to its large scale, strong flexibility, and development and utilization not restricted by geographical location. However, there is heat loss during air compression and expansion, heat loss of exhaust waste heat during expansion and power generation, and after the storage-release cycle, due to the entropy heat increase of electricity-heat conversion during energy storage, some of the stored high-temperature heat cannot be utilized after the expansion and power generation process ends, which affects the efficiency of the compressed air energy storage system.

[0003] In related technologies, some studies have connected the heat exchange system in the compressed air energy storage system with the plant heating network system, and used the surplus electricity in the plant to drive the compressed air energy storage system. The waste heat generated in the compressed air energy storage system is used for heating the plant to achieve heat transfer and utilization. There are also studies that directly use the exhaust of the expansion power generation system to drive the small expansion ratio expansion system to generate electricity and improve the electricity-to-electricity conversion efficiency. However, the pressure and temperature of the exhaust of the expansion power generation system are relatively low, and the power generation capacity is limited.

[0004] The exhaust waste heat in the compressed air energy storage system is reused by the method in the related technology. Since the exhaust pressure and temperature of the expansion power generation system are relatively low, the amount of electricity that can be generated and the output power are limited, and the energy conversion efficiency is still low. Therefore, it is necessary to further study the method of using waste heat for compressed air energy storage system power generation and increase the inlet temperature of the expansion power generation system to effectively improve the energy conversion efficiency. Summary of the invention

[0005] The embodiment of the present invention provides a compressed air energy storage system with multi-stage waste heat utilization, which can effectively utilize the waste heat of the compressed air energy storage system, the waste heat of other systems in combined operation and the high-temperature heat storage during the compression process, and improve the energy conversion efficiency of the compressed air energy storage system. The technical solution is as follows:

[0006] An embodiment of the present invention provides a compressed air energy storage system for multi-stage waste heat utilization, comprising:

[0007] Air compression system, heat exchange system, gas storage system, first expansion power generation system, second expansion power generation system and multi-stage waste heat utilization system,

[0008] The heat exchange system comprises a first heat exchanger, a second heat exchanger, a heat storage device and a cold storage device.

[0009] The multi-stage waste heat utilization system includes a third heat exchanger, a fourth heat exchanger and a fifth heat exchanger.

[0010] The first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger and the fifth heat exchanger each include a low-temperature side flow channel and a high-temperature side flow channel,

[0011] The air compression system is connected to the upstream of the high-temperature side flow passage of the first heat exchanger, the downstream of the high-temperature side flow passage of the first heat exchanger is connected to the inlet of the gas storage system, the outlet of the gas storage system is connected to the upstream of the low-temperature side flow passage of the second heat exchanger, the downstream of the low-temperature side flow passage of the second heat exchanger is connected to the first expansion power generation system, the exhaust port of the first expansion power generation system is connected to the upstream of the high-temperature side flow passage of the third heat exchanger, and the downstream of the high-temperature side flow passage of the third heat exchanger is connected to the outside,

[0012] The outlet of the gas storage system is also connected to the upstream of the low-temperature side flow channel of the third heat exchanger, the downstream of the low-temperature side flow channel of the third heat exchanger is connected to the upstream of the low-temperature side flow channel of the fourth heat exchanger, and the downstream of the low-temperature flow channel of the fourth heat exchanger is connected to the second expansion power generation system.

[0013] The high-temperature side flow channel of the second heat exchanger is connected to the heat storage device upstream, the high-temperature side flow channel of the second heat exchanger is connected to the cold storage device downstream, the low-temperature side flow channel of the first heat exchanger is connected to the energy storage device upstream, and the low-temperature side flow channel of the first heat exchanger is connected to the heat storage device downstream,

[0014] The high-temperature side flow channel of the fourth heat exchanger is connected to the heat storage device upstream, and the high-temperature side flow channel of the fourth heat exchanger is connected to the cold storage device downstream.

[0015] Optionally, the first expansion power generation system includes a first expansion device and a first generator, the second expansion power generation system includes a second expansion device and a second generator, and the rated power generation power of the first generator is greater than the rated power generation power of the second generator.

[0016] Optionally, the gas storage system includes a first gas storage device and a second gas storage device, the high-temperature side flow channel downstream of the first heat exchanger is connected to the air inlet of the first gas storage device and the air inlet of the second gas storage device, the air outlet of the first gas storage device is respectively connected to the low-temperature side flow channel upstream of the third heat exchanger and the low-temperature side flow channel upstream of the second heat exchanger, and the air outlet of the second gas storage device is respectively connected to the low-temperature side flow channel upstream of the third heat exchanger and the low-temperature side flow channel upstream of the second heat exchanger.

[0017] Optionally, a first switch valve and a first throttle valve are provided between the downstream of the high-temperature side flow channel of the first heat exchanger and the air inlet of the first air storage device, and between the downstream of the high-temperature side flow channel of the first heat exchanger and the air inlet of the second air storage device.

[0018] Optionally, a second throttle valve is provided at the air outlet of the first air storage device and the air outlet of the second air storage device, and a second switch valve is provided between the outlet of the second throttle valve and the upstream of the low-temperature side flow channel of the second heat exchanger and the upstream of the low-temperature side flow channel of the third heat exchanger.

[0019] Optionally, the initial gas pressures of the first gas storage device and the second gas storage device, the minimum working pressure of the first expansion device, and the minimum working pressure of the second expansion device decrease in sequence.

[0020] Optionally, a third switch valve is provided between the heat storage device and the upstream of the high-temperature side flow passage of the second heat exchanger, and between the heat storage device and the upstream of the high-temperature side flow passage of the fourth heat exchanger.

[0021] Optionally, the multi-stage waste heat utilization compressed air energy storage system also includes other waste heat generation systems, and the other waste heat generation systems include a heat storage device and a conversion device. The multi-stage waste heat utilization system also includes a fifth heat exchanger, and the low-temperature side flow channel upstream of the fifth heat exchanger is connected to the low-temperature side flow channel downstream of the third heat exchanger, the low-temperature side flow channel downstream of the fifth heat exchanger is connected to the upstream of the low-temperature side flow channel of the fourth heat exchanger, the high-temperature side flow channel upstream of the fifth heat exchanger is connected to the heat storage device, and the high-temperature side flow channel downstream of the fifth heat exchanger is connected to the cold storage device.

[0022] Optionally, the other waste heat generation system includes at least one of a flywheel energy storage system, a hydrogen production system and an electrochemical energy storage system.

[0023] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0024] (1) The system can effectively utilize the exhaust waste heat and high-temperature heat storage of the compressed air energy storage system to improve the energy conversion efficiency of the compressed air energy storage system;

[0025] (2) The compressed energy storage system utilizes the waste heat from the operation of other systems such as the flywheel energy storage system, hydrogen production system, and electrochemical energy storage system, effectively realizing heat-to-electricity conversion and improving the overall energy conversion efficiency of the combined operation system;

[0026] (3) The parallel connection of expansion power generation systems with different power generation levels increases the maximum output power of the compressed air energy storage system, realizes multi-level power generation system power generation, and expands the operating range of the compressed air energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 It is a schematic structural diagram of a compressed air energy storage system for multi-stage waste heat utilization provided in an embodiment of the present invention.

[0029] In the figure:

[0030] 1-air compression system; 3-gas storage system; 4-first expansion power generation system; 5-second expansion power generation system; 6-multi-stage waste heat utilization system; 8-other waste heat generation systems; 21-first heat exchanger; 22-second heat exchanger; 23-heat storage device; 24-cold storage device; 31-first gas storage device; 32-second gas storage device; 41-first expansion device; 42-first generator; 51-second expansion device; 52-second generator; 61-third heat exchanger; 62-fourth heat exchanger; 63-fifth heat exchanger; 71-first switch valve; 72-first throttle valve; 73-second throttle valve; 74-second switch valve; 75-third switch valve; 82-heat storage device; 83-conversion device. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] In related technologies, some studies have connected the heat exchange system in the compressed air energy storage system with the plant heating network system, and used the surplus electricity in the plant to drive the compressed air energy storage system. The waste heat generated in the compressed air energy storage system is used for heating the plant to achieve heat transfer and utilization. There are also studies that directly use the exhaust of the expansion power generation system to drive the small expansion ratio expansion system to generate electricity and improve the electricity-to-electricity conversion efficiency. However, the pressure and temperature of the exhaust of the expansion power generation system are relatively low, and the power generation capacity is limited.

[0033] The exhaust waste heat in the compressed air energy storage system is reused by the method in the related technology. Since the exhaust pressure and temperature of the expansion power generation system are relatively low, the amount of electricity that can be generated and the output power are limited, and the energy conversion efficiency is still low. Therefore, it is necessary to further study the method of using waste heat for compressed air energy storage system power generation and increase the inlet temperature of the expansion power generation system to effectively improve the energy conversion efficiency.

[0034] Figure 1Schematic diagram of the structure of a compressed air energy storage system for multi-stage waste heat utilization provided by an embodiment of the present invention. Figure 1 As shown, through practice, an embodiment of the present invention provides a compressed air energy storage system with multi-stage waste heat utilization, including an air compression system 1, a heat exchange system, an air storage system 3, a first expansion and power generation system 4, a second expansion and power generation system 5 and a multi-stage waste heat utilization system 6.

[0035] The heat exchange system includes a first heat exchanger 21, a second heat exchanger 22, a heat storage device 23 and a cold storage device 24. The multi-stage waste heat utilization system 6 includes a third heat exchanger 61, a fourth heat exchanger 62 and a fifth heat exchanger 63. The first heat exchanger 21, the second heat exchanger 22, the third heat exchanger 61, the fourth heat exchanger 62 and the fifth heat exchanger 63 all include a low-temperature side flow channel and a high-temperature side flow channel.

[0036] The air compression system 1 is connected to the upstream of the high-temperature side flow channel of the first heat exchanger 21, the downstream of the high-temperature side flow channel of the first heat exchanger 21 is connected to the inlet of the gas storage system 3, the outlet of the gas storage system 3 is connected to the upstream of the low-temperature side flow channel of the second heat exchanger 22, the downstream of the low-temperature side flow channel of the second heat exchanger 22 is connected to the first expansion power generation system 4, the exhaust port of the first expansion power generation system 4 is connected to the upstream of the high-temperature side flow channel of the third heat exchanger 61, and the downstream of the high-temperature side flow channel of the third heat exchanger 61 is connected to the outside.

[0037] The outlet of the gas storage system 3 is also connected to the upstream of the low-temperature side flow channel of the third heat exchanger 61, the downstream of the low-temperature side flow channel of the third heat exchanger 61 is connected to the upstream of the low-temperature side flow channel of the fourth heat exchanger 62, and the downstream of the low-temperature flow channel of the fourth heat exchanger 62 is connected to the second expansion power generation system 5.

[0038] The high-temperature side flow channel of the second heat exchanger 22 is connected to the heat storage device 23 upstream, and the high-temperature side flow channel of the second heat exchanger 22 is connected to the cold storage device 24 downstream. The low-temperature side flow channel of the first heat exchanger 21 is connected to the cold storage device 24 upstream, and the low-temperature side flow channel of the first heat exchanger 21 is connected to the heat storage device 23 downstream.

[0039] The high-temperature side flow passage of the fourth heat exchanger 62 is connected to the heat storage device 23 upstream, and the high-temperature side flow passage of the fourth heat exchanger 62 is connected to the cold storage device 24 downstream.

[0040] In the embodiment of the present invention, the air compression system 1 is connected to the off-peak electricity of the power grid or the surplus electricity of new energy power generation such as wind power and photovoltaic power, and is driven by the motor to generate compressed air and store it in the gas storage system 3. A first heat exchanger 21 and a second heat exchanger 22 are arranged on both sides of the inlet and outlet of the gas storage system 3. Before entering the gas storage system 3, the compressed high-temperature and high-pressure air will first be cooled by heat exchange with the low-temperature heat exchange medium discharged from and passed through the cold storage device 24 through the first heat exchanger 21, and the high-temperature heat exchange medium after heat exchange is stored in the heat storage device 23. When expansion power generation is required, the air in the gas storage system 3 is divided into two paths, one of which passes through the second heat exchanger 22, and is heated by heat exchange with the high-temperature heat exchange medium discharged from and passed through the heat storage device 23 in the second heat exchanger 22. The heated high-temperature and high-pressure gas enters the first expansion power generation system 4, driving the first expansion power generation system 4 to generate power. The heat exchange medium after heat exchange is re-introduced into the cold storage device 24 to realize the cold and hot cycle. At the same time, the other air path passes through the multi-stage waste heat utilization system 6 composed of the third heat exchanger 61 and the fourth heat exchanger 62 in sequence. In the third heat exchanger 61, the gas will perform a primary heat exchange with the high-temperature gas discharged from the first expansion power generation system 4 when it is working, and then in the fourth heat exchanger 62, it will perform a secondary heat exchange with the high-temperature heat exchange medium discharged from and passed through the heat storage device 23. After the multi-stage heat exchange, the high-temperature and high-pressure gas enters the second expansion power generation system 5 to drive the second expansion power generation system 5 to generate electricity. The electric energy generated by the first expansion power generation system 4 and the second expansion power generation system 5 can be connected to the power system of the relevant plant area to realize electric-electric conversion.

[0041] The compressed air energy storage system with multi-stage waste heat utilization provided by the embodiment of the present invention is improved on the basis of the traditional use of the gas generated by the air compression system to drive the expansion power generation system to generate work and power. Two sets of parallel first expansion power generation system 4 and second expansion power generation system 5 are set at the rear end of the gas storage system 3, wherein the high-pressure air introduced into the first expansion power generation system 4 through the gas storage system 3 passes through the heat exchange system set at both ends of the gas storage system 3, and is heat exchanged and heated in the second heat exchanger 22, and the excess exhaust gas generated by the first expansion power generation system 4 during operation is passed into the third heat exchanger 61 of the multi-stage waste heat utilization system 6. The high-pressure air introduced into the newly added second expansion power generation system 5 passes through the multi-stage waste heat utilization system 6, exchanges heat with the high-temperature exhaust gas of the first expansion power generation system 4 in the third heat exchanger 61, and exchanges heat with the high-temperature heat exchange medium in the heat storage device 23 in the fourth heat exchanger 62 to achieve multi-stage heat exchange and temperature increase. The heat exchange medium after heat exchange with the two-way gas in the second heat exchanger 22 and the fourth heat exchanger 62 re-enters the cold storage device 24 to achieve self-circulation. It can effectively utilize the exhaust waste heat and high-temperature heat storage in the compressed air energy storage system to improve the energy conversion efficiency of the compressed air energy storage system.

[0042] Exemplarily, in an embodiment of the present invention, since the heating of the gas entering the first expansion power generation system completely relies on the second heat exchanger 22, and the multi-stage waste heat utilization system 6 is provided with multiple groups of heat exchangers for gas heating, the temperature requirement for the heat exchange medium used for heat exchange with the gas in the fourth heat exchanger 62 can be lower than that of the second heat exchanger 22. Therefore, in one possible implementation method, the diameter of the connecting pipe between the upstream of the high-temperature side flow channel of the fourth heat exchanger 62 and the heat storage device 23 and the downstream of the cold storage device 24 can be smaller than the self-circulating heat exchange medium pipe in the heat exchange system, so as to reduce the flow rate of the high-temperature heat exchange medium entering the cold storage device 24 and ensure the heat exchange effect in the second heat exchanger 22.

[0043] Optionally, the first expansion power generation system 4 includes a first expansion device 41 and a first generator 42, and the second expansion power generation system 5 includes a second expansion device 51 and a second generator 52, and the rated power generation power of the first generator 42 is greater than the rated power generation power of the second generator 52. Exemplarily, in an embodiment of the present invention, the rated power of the first generator 42 is greater than the rated power generation power of the second generator 52, and the number of expansion poles and the expansion ratio requirement of the second expansion device 51 corresponding to the second generator 52 are smaller than those of the first expansion device 41. When the first expansion power generation system 4 and the second expansion power generation system 5 are operated in parallel, the second expansion power generation system 5 can be used as a secondary power generation system, and work independently or together according to the actual power generation power and power generation demand of the plant area and the compressed air energy storage system, so as to realize power generation of a multi-level power generation system and expand the operating range of the compressed air energy storage system.

[0044] Exemplarily, in the embodiment of the present invention, the first expansion device 41 and the second expansion device 51 are composed of a single expansion machine or a plurality of expansion machines connected in series.

[0045] Optionally, the gas storage system 3 includes a first gas storage device 31 and a second gas storage device 32, the high-temperature side flow channel downstream of the first heat exchanger 21 is connected to the air inlet of the first gas storage device 31 and the air inlet of the second gas storage device 32, the gas outlet of the first gas storage device 31 is respectively connected to the low-temperature side flow channel upstream of the third heat exchanger 61 and the low-temperature side flow channel upstream of the second heat exchanger 22, and the gas outlet of the second gas storage device 32 is respectively connected to the low-temperature side flow channel upstream of the third heat exchanger 61 and the low-temperature side flow channel upstream of the second heat exchanger 22. Exemplarily, in the embodiment of the present invention, the gas storage system 3 is composed of two parallel first gas storage devices 31 and second gas storage devices 32 to form a gas storage device group, both of which are connected to the downstream of the high-temperature side flow channel of the first heat exchanger 21 through a branch pipe, and the first switch valve 71 and the first throttle valve 72 are arranged between the downstream outlet of the high-temperature side flow channel of the first heat exchanger 21 and the air inlet of the first gas storage device 31, and between the downstream outlet of the high-temperature side flow channel of the first heat exchanger 21 and the air inlet of the second gas storage device 32. The outlet of the first gas storage device 31 and the rear end of the outlet of the second gas storage device 32 are divided into two paths by a three-way pipe, respectively connected to the upstream of the low-temperature side flow channel of the second heat exchanger 22 and the upstream of the low-temperature side flow channel of the third heat exchanger 61. The first gas storage device 31 and the second gas storage device 32 can both supply gas to the first expansion power generation system 4 and the second expansion power generation system 5. The second throttle valve 73 is respectively arranged on the main pipe at the rear end of the air outlet of the first air storage device 31 and the air outlet of the second air storage device 32, and the second switch valve 74 is respectively arranged on the branch pipes of the two three-way pipes connected to the second heat exchanger 22 and the third heat exchanger 61. The air storage system 3 sequentially stores high-pressure gas through the air compression system 1 until the internal air pressure reaches the set value, and the air inlet of the first air storage device 31 and the second air storage device 32 is controlled by the first switch valve 71 at the front section to control the air intake, and the air intake flow is controlled by the first throttle valve 72, and the air outlet is controlled by the second switch valve 74 at the rear end, and the air outlet flow entering the second heat exchanger 22 and the third heat exchanger 61 is respectively controlled by the second throttle valve 73 to ensure that the air pressure and flow in the pipeline components meet the needs and rated standards.

[0046] Optionally, a third switch valve 75 is provided between the heat storage device 23 and the upstream of the high-temperature side flow passage of the second heat exchanger 22, and between the heat storage device 23 and the upstream of the high-temperature side flow passage of the fourth heat exchanger 62. Exemplarily, in the embodiment of the present invention, the third switch valve 75 is provided at the front end of the second heat exchanger 22 and the fourth heat exchanger 62, which need to utilize the high-temperature heat exchange medium in the heat storage device 23 to heat the passing gas, so as to control the circulation of the heat source, and can start and stop the heat source supply following the start and stop of the corresponding first expansion device 41 and the second expansion device 51, so as to avoid unnecessary heat loss and improve the heat exchange efficiency.

[0047] Optionally, the compressed air energy storage system with multi-stage waste heat utilization further includes other waste heat generation systems 8. The other waste heat generation systems 8 include a heat storage device 82 and a conversion device 83. The multi-stage waste heat utilization system 6 further includes a fifth heat exchanger 63. The upstream of the low-temperature side flow channel of the fifth heat exchanger 63 is connected to the downstream of the low-temperature side flow channel of the third heat exchanger 61, and the downstream of the low-temperature side flow channel of the fifth heat exchanger 63 is connected to the upstream of the low-temperature side flow channel of the fourth heat exchanger 62. The upstream of the high-temperature side flow channel of the fifth heat exchanger 63 is connected to the heat storage device 82 such as flywheel energy storage, hydrogen production system, and electrochemical energy storage. The downstream of the high-temperature side flow channel of the fifth heat exchanger 63 is connected to the cold storage device 24. Exemplarily, in the embodiment of the present invention, an additional fifth heat exchanger 63 can be serially connected in the multi-stage waste heat utilization system 6 to access other waste heat generation systems 8. The other waste heat generation systems include at least one of, but are not limited to, flywheel energy storage, hydrogen production system, and electrochemical energy storage system, and can be combined and used according to actual conditions. The heat exchange medium for cooling discharged by the heat storage device 82 in the other waste heat generation systems 8 is used as a high-temperature medium to heat the passing air through the fifth heat exchanger 63, and finally enters the cold storage device 24 to jointly circulate.

[0048] Optionally, the initial air pressures of the first air storage device 31 and the second air storage device 32, the minimum operating pressure of the first expansion device 41, and the minimum operating pressure of the second expansion device 51 decrease in sequence. Exemplarily, in the embodiment of the present invention, the initial air pressures of the first air storage device 31 and the second air storage device 32 are p1, the minimum operating pressure of the first expansion device 41 is p2, the minimum operating pressure of the second expansion device 51 is p3, and p1 > p2 > p3. Further, the rated power generation of the first expansion power generation system 4 is P1, and the rated power generation of the second expansion power generation system 5 is P2, and P1 > P2.

[0049] According to the range of the power generation power P required by the compressed air energy storage system, the power generation methods of the first expansion power generation system 4 and the second expansion power generation system 5 are as follows:

[0050] When the power generation power required by the compressed air energy storage system is in the range of P2 < P < P1, the first expansion power generation system 4 operates. By means of the pressure measuring device, one of the first air storage device 31 and the second air storage device 32 that meets the pressure range, i.e., p2 < p < p1, sequentially drives the first expansion power generation system 4 to generate electricity through the corresponding switching valve and throttle valve. The exhaust gas preheating for power generation of the first expansion power generation system 4 can drive the second expansion power generation system 5 to operate through the multi-stage waste heat utilization system 6, and the generated electricity is transmitted to other waste heat generation systems 8 composed of a jointly operating flywheel energy storage system, electrochemical energy storage, hydrogen production system, etc. or used locally in the plant power system.

[0051] When the power generation power required by the compressed air energy storage system is in the range of P1 < P < P1 + P2, the first expansion power generation system 4 and the second expansion power generation system 5 work simultaneously; the first expansion power generation system 4 works, and one of the first gas storage device 31 and the second gas storage device 32 that meet the pressure range, i.e., p2 < p < p1, is determined through the pressure measuring device, and successively drives the first expansion power generation system 4 to generate electricity by controlling the corresponding switching valve and throttle valve. At the same time, the second expansion power generation system 5 works, and one of the first gas storage device 31 and the second gas storage device 32 that meet the pressure range, i.e., p3 < p, is determined through the pressure measuring device, and the gas storage device with p3 < p < p2 is preferentially used, and successively drives the second expansion power generation system 5 to generate electricity by controlling the switching valve and throttle valve. The high-pressure air at the inlet of the second expansion power generation system 5 is successively subjected to multi-stage heating through the exhaust preheating of the first expansion power generation system 4, the heat storage device 82, and the heat storage device to make full use of the system heat. Among them, in order to ensure that the air pressure meets the standard, the first expansion power generation system 4 and the second expansion power generation system 5 cannot use the same gas storage device at the same time.

[0052] When the power generation power P required by the energy storage system is less than P2, the second expansion power generation system 5 works. One of the first gas storage device 31 and the second gas storage device 32 that meet the pressure range, i.e., p3 < p, is determined through the pressure measuring device, and the gas storage device with p3 < p < p2 is preferentially used, and successively drives the second expansion power generation system 5 to generate electricity by controlling the switching valve and throttle valve. The high-pressure air at the inlet of the second expansion power generation system 5 is successively subjected to multi-stage heating through the heat supply of the heat storage device 82 and the heat storage device 23 to make full use of the system heat.

[0053] The compressed air energy storage system operating in the above manner connects the first expansion power generation system 4 and the second expansion power generation system 5 with different power generation power levels in parallel to increase the maximum output power of the compressed air energy storage system, realizes power generation by multi-level power generation systems, and further expands the operating range of the compressed air energy storage system.

[0054] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0055] The above descriptions are merely optional embodiments of the present invention and are 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 protection scope of the present invention.

Claims

1. A compressed air energy storage system for multi-stage waste heat utilization, characterized in that: include: An air compression system (1), a heat exchange system, an air storage system (3), a first expansion power generation system (4), a second expansion power generation system (5), a multi-stage waste heat utilization system (6) and other waste heat generation systems (8), The heat exchange system comprises a first heat exchanger (21), a second heat exchanger (22), a heat storage device (23) and a cold storage device (24), The multi-stage waste heat utilization system (6) comprises a third heat exchanger (61), a fourth heat exchanger (62) and a fifth heat exchanger (63). The first heat exchanger (21), the second heat exchanger (22), the third heat exchanger (61), the fourth heat exchanger (62) and the fifth heat exchanger (63) each include a low-temperature side flow channel and a high-temperature side flow channel. The air compression system (1) is connected to the upstream of the high-temperature side flow channel of the first heat exchanger (21); the downstream of the high-temperature side flow channel of the first heat exchanger (21) is connected to the inlet of the gas storage system (3); the outlet of the gas storage system (3) is connected to the upstream of the low-temperature side flow channel of the second heat exchanger (22); the downstream of the low-temperature side flow channel of the second heat exchanger (22) is connected to the first expansion power generation system (4); the exhaust port of the first expansion power generation system (4) is connected to the upstream of the high-temperature side flow channel of the third heat exchanger (61); and the downstream of the high-temperature side flow channel of the third heat exchanger (61) is connected to the outside. The outlet of the gas storage system (3) is also connected to the upstream of the low-temperature side flow channel of the third heat exchanger (61), the downstream of the low-temperature side flow channel of the third heat exchanger (61) is connected to the upstream of the low-temperature side flow channel of the fourth heat exchanger (62), and the downstream of the low-temperature flow channel of the fourth heat exchanger (62) is connected to the second expansion power generation system (5). The high-temperature side flow channel of the second heat exchanger (22) is connected to the heat storage device (23) upstream, the high-temperature side flow channel of the second heat exchanger (22) is connected to the cold storage device (24) downstream, the low-temperature side flow channel of the first heat exchanger (21) is connected to the cold storage device (24) upstream, and the low-temperature side flow channel of the first heat exchanger (21) is connected to the heat storage device (23) downstream. The high-temperature side flow channel of the fourth heat exchanger (62) is connected to the heat storage device (23) upstream, and the high-temperature side flow channel of the fourth heat exchanger (62) is connected to the cold storage device (24) downstream; The other waste heat generation system (8) includes a heat storage device (82) and a conversion device (83); the low-temperature side flow channel upstream of the fifth heat exchanger (63) is connected to the low-temperature side flow channel downstream of the third heat exchanger (61); the low-temperature side flow channel downstream of the fifth heat exchanger (63) is connected to the low-temperature side flow channel upstream of the fourth heat exchanger (62); the high-temperature side flow channel upstream of the fifth heat exchanger (63) is connected to the heat storage device (82); and the high-temperature side flow channel downstream of the fifth heat exchanger (63) is connected to the cold storage device (24).

2. The compressed air energy storage system for multi-stage waste heat utilization according to claim 1 is characterized in that: The first expansion power generation system (4) comprises a first expansion device (41) and a first generator (42), and the second expansion power generation system (5) comprises a second expansion device (51) and a second generator (52), wherein the rated power generation power of the first generator (42) is greater than the rated power generation power of the second generator (52).

3. The compressed air energy storage system for multi-stage waste heat utilization according to claim 2 is characterized in that: The gas storage system (3) comprises a first gas storage device (31) and a second gas storage device (32); the high-temperature side flow channel downstream of the first heat exchanger (21) is connected to the air inlet of the first gas storage device (31) and the air inlet of the second gas storage device (32); the gas outlet of the first gas storage device (31) is respectively connected to the low-temperature side flow channel upstream of the third heat exchanger (61) and the low-temperature side flow channel upstream of the second heat exchanger (22); the gas outlet of the second gas storage device (32) is respectively connected to the low-temperature side flow channel upstream of the third heat exchanger (61) and the low-temperature side flow channel upstream of the second heat exchanger (22).

4. The compressed air energy storage system for multi-stage waste heat utilization according to claim 3 is characterized in that: A first switch valve (71) and a first throttle valve (72) are provided between the downstream of the high-temperature side flow channel of the first heat exchanger (21) and the air inlet of the first air storage device (31), and between the downstream of the high-temperature side flow channel of the first heat exchanger (21) and the air inlet of the second air storage device (32).

5. The compressed air energy storage system for multi-stage waste heat utilization according to claim 3 is characterized in that: A second throttle valve (73) is provided at the air outlet of the first air storage device (31) and the air outlet of the second air storage device (32), and a second switch valve (74) is provided between the outlet of the second throttle valve (73) and the upstream of the low-temperature side flow channel of the second heat exchanger (22) and the upstream of the low-temperature side flow channel of the third heat exchanger (61).

6. The compressed air energy storage system for multi-stage waste heat utilization according to claim 3 is characterized in that: The initial gas pressures of the first gas storage device (31) and the second gas storage device (32), the minimum working pressure of the first expansion device (41), and the minimum working pressure of the second expansion device (51) decrease in sequence.

7. The compressed air energy storage system for multi-stage waste heat utilization according to claim 1, characterized in that: A third switch valve (75) is provided between the heat storage device (23) and the upstream of the high-temperature side flow channel of the second heat exchanger (22), and between the heat storage device (23) and the upstream of the high-temperature side flow channel of the fourth heat exchanger (62).

8. The compressed air energy storage system for multi-stage waste heat utilization according to claim 1, characterized in that: The other waste heat generation system (8) comprises at least one of a flywheel energy storage system, a hydrogen production system and an electrochemical energy storage system.

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