A waste heat utilization transcritical recompression carbon dioxide energy storage system

Abstract

The application discloses a waste heat utilization transcritical recompression carbon dioxide energy storage system, and is characterized in that a recompression module containing a recompression machine, a water heat storage and release circuit and a molten salt heat storage and release circuit is arranged, so that on one hand, the loss caused by a large heat exchange temperature difference in the heat recovery process of the working medium is obviously reduced, and on the other hand, the loss generated in the heat dissipation process of the system to the external environment is greatly reduced; meanwhile, the main compression module and the recompression module share a low-pressure carbon dioxide storage tank and a high-pressure carbon dioxide storage tank, so that the energy storage density of the energy storage system is improved, and the compactness of the energy storage system is improved.

Description

Technical Field

[0001] This invention relates to the field of waste heat recovery and utilization technology, and in particular to a waste heat utilization transcritical recompression carbon dioxide energy storage system. Background Technology

[0002] Traditional compressed energy storage systems suffer from asynchronous energy storage and release, resulting in a significant amount of unused residual heat after the working fluid completes its work. Furthermore, energy loss occurs due to energy mismatch and differences in energy quality. loss. Summary of the Invention

[0003] The purpose of this invention is to provide a transcritical recompression carbon dioxide energy storage system for waste heat utilization, thereby improving the efficiency of waste heat recovery from exhaust gas.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] A waste heat utilization transcritical recompression carbon dioxide energy storage system includes a first low-pressure liquid tank and a high-pressure gas tank interconnected to form a closed loop via a main energy storage pipeline and a main energy release pipeline, a first energy storage branch line disposed on the main energy storage pipeline, and a first energy release branch line disposed on the main energy release pipeline. A constant-temperature heater, a compressor, and a first cooler are sequentially arranged on the main energy storage pipeline away from the first low-pressure liquid tank. The two ends of the first energy storage branch line are respectively connected to the main energy storage pipeline between the constant-temperature heater and the compressor, and the main energy storage pipeline between the compressor and the first cooler. A first low-temperature heater is sequentially arranged on the first energy storage branch line away from the constant-temperature heater. The compressor and the second cooler are included. The main energy release pipeline, along the direction away from the high-pressure gas tank, is sequentially equipped with a second cryogenic heater, a cryogenic regenerator, a high-temperature regenerator, a first high-temperature heater, a first turbine expander, a second high-temperature heater, a second turbine expander, a third cooler, and a constant-temperature cooler. The main energy release pipeline extends from the second turbine expander and then sequentially flows back through the high-temperature regenerator and the cryogenic regenerator. One end of the first energy release branch is connected to the main energy release pipeline between the second cryogenic heater and the cryogenic regenerator, and the other end is connected to the main energy release pipeline between the cryogenic regenerator and the high-temperature regenerator before the return flow. A third cryogenic heater is installed on the first energy release branch.

[0006] Preferably, the first energy storage branch and the energy storage main branch, and the first energy release branch and the energy release main branch are all connected by a splitter.

[0007] Preferably, both the constant temperature heater and the constant temperature cooler are connected to a constant temperature source.

[0008] Preferably, a throttling valve is provided on the energy storage branch line between the constant temperature heater and the first low-pressure liquid storage tank.

[0009] Preferably, the first low-temperature heater and the third cooler are connected by a first branch to form a closed loop, and a first cold water pool, a first air cooler, and a first hot water pool are respectively provided between the first low-temperature heater and the third cooler.

[0010] Preferably, the first air cooler is located near the first cryogenic heater.

[0011] Preferably, the second cooler and the third cryogenic heater are connected by a second branch to form a closed loop, and a cryogenic molten salt tank, a second air cooler, and a third liquid storage tank are respectively provided between the second cooler and the third cryogenic heater.

[0012] Preferably, the second air cooler is located near the third cryogenic heater.

[0013] Preferably, the first cooler and the first low-temperature heater are connected by a third branch to form a closed loop, and a second cold water pool, a third air cooler, and a second hot water pool are respectively provided between the first cooler and the first low-temperature heater.

[0014] Preferably, the third air cooler is located near the first cryogenic heater.

[0015] The present invention achieves the following technical effects compared to the prior art:

[0016] 1. This invention comprises a compressor, a re-compressor, a first turboexpander, a second turboexpander, a high-temperature regenerator, a low-temperature regenerator, a high-temperature heater, a cooler, a throttling valve, and a constant-temperature pool, connected by pipelines to form a reheat arrangement system, a waste heat recovery system, and a recompression system. The reheat arrangement system first exchanges heat between the input high-temperature working fluid and the incoming working fluid, then performs work. The secondary reheat arrangement system increases the temperature of the working fluid at the inlet of the high-temperature regenerator, reducing the heat absorbed by the working fluid in the high-temperature heater and lowering the quality of the waste heat at the tail end. After passing through the constant-temperature pool, the working fluid becomes liquid and is stored in a low-pressure liquid storage tank, reducing waste heat loss from the flue gas. The cooling system absorbs waste heat at the tail end that cannot be absorbed in traditional compression energy storage systems, reducing heat loss in the system and improving system efficiency. Efficiency and energy density have been further improved.

[0017] 2. In this invention, a flow splitting method is adopted at the compressor inlet, and the tail heat recovery system adopts a two-stage arrangement to circulate and introduce high-temperature gas from the tail, so that the energy quality is further matched.

[0018] 3. This invention reduces the exhaust temperature after power generation by splitting the working fluid at the inlet of the regenerator. The arrangement of the tail regenerator and cooler enables the temperature of the carbon dioxide after power generation to reach a preset value, further absorbing the residual heat of the carbon dioxide after power generation that could not be absorbed in the first place, reducing the exhaust loss after the expander. The arrangement of the cooler and regenerator solves the problem of absorbing residual heat from the tail exhaust in compression energy storage. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the present invention;

[0021] The components include: 1. First low-pressure liquid storage tank; 2. Constant temperature source; 3. Constant temperature heater; 4. Constant temperature cooler; 5. First air cooler; 6. First branch circuit; 7. First cold water pool; 8. Diverter; 9. First low-temperature heater; 10. Recompressor; 11. Second cooler; 12. Compressor; 13. First cooler; 14. Second cold water pool; 15. High-pressure gas tank; 16. Third air cooler; 17. Second low-temperature heater; 18. Low-temperature regenerator. 19. High-temperature regenerator; 20. First high-temperature heater; 21. First turbine expander; 22. Second high-temperature heater; 23. Second turbine expander; 24. First energy release branch; 25. Third cooler; 26. Second branch; 27. First hot water tank; 28. High-temperature molten salt tank; 29. ​​Third low-temperature heater; 30. Low-temperature molten salt tank; 31. Third air cooler; 32. Third branch; 33. Second hot water tank; 34. First energy storage branch. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The purpose of this invention is to provide a transcritical recompression carbon dioxide energy storage system for waste heat utilization, thereby improving the efficiency of waste heat recovery from exhaust gas.

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] refer to Figure 1 A waste heat utilization transcritical recompression carbon dioxide energy storage system includes a first low-pressure liquid tank and a high-pressure gas tank interconnected and forming a closed loop via a main energy storage pipeline and a main energy release pipeline, a first energy storage branch on the main energy storage pipeline, and a first energy release branch on the main energy release pipeline. A constant-temperature heater, a compressor, and a first cooler are sequentially arranged on the main energy storage pipeline away from the first low-pressure liquid tank. The two ends of the first energy storage branch are respectively connected to the main energy storage pipeline between the constant-temperature heater and the compressor, and the main energy storage pipeline between the compressor and the first cooler. A first low-temperature heater, a recompressor, and a second cooler are sequentially arranged on the first energy storage branch away from the constant-temperature heater. A second low-temperature heater, a low-temperature regenerator, a high-temperature regenerator, a first high-temperature heater, a first turbine expander, a second high-temperature heater, a second turbine expander, and a third cooler are sequentially arranged on the main energy release pipeline away from the high-pressure gas tank. The system includes a cooler and a constant-temperature cooler. The main energy release pipeline extends from the second turbine expander and then flows back through a high-temperature regenerator and a low-temperature regenerator in sequence. One end of the first energy release branch is connected to the main energy release pipeline between the second low-temperature heater and the low-temperature regenerator, and the other end is connected to the main energy release pipeline between the low-temperature regenerator and the high-temperature regenerator before the return flow. A third low-temperature heater is installed on the first energy release branch. This invention forms a reheat arrangement system, a waste heat recovery system, and a recompression system by setting up a compressor, a recompressor, a first turbine expander, a second turbine expander, a high-temperature regenerator, a low-temperature regenerator, a high-temperature heater, a cooler, a throttling valve, and a constant-temperature pool, which are connected by the cooperation of the pipelines. The reheat arrangement system first exchanges heat between the input high-temperature working fluid and the incoming working fluid, and then performs work. The arrangement of the low-temperature regenerator is to ensure that the carbon dioxide in the main energy release pipeline and the carbon dioxide in the first energy release branch reach the same temperature before the inlet of the high-temperature regenerator, avoiding unnecessary... This reduces heat loss and lowers the quality of residual heat. The working fluid, after passing through a constant-temperature pool, becomes a liquid and is stored in a low-pressure liquid storage tank. Meanwhile, the cooling system absorbs and utilizes residual heat that traditional compression energy storage systems cannot absorb, reducing heat loss in the system and improving system efficiency. Efficiency and energy density have been further improved.

[0026] refer to Figure 1 The first energy storage branch and the energy storage main branch, as well as the first energy release branch and the energy release main branch, are all connected by a splitter.

[0027] refer to Figure 1 Both the constant temperature heater and the constant temperature cooler are connected to a constant temperature source.

[0028] refer to Figure 1 A throttling valve is installed on the energy storage branch pipeline between the constant temperature heater and the first low-pressure liquid storage tank.

[0029] refer to Figure 1 The first low-temperature heater and the third cooler are connected by a first branch to form a closed loop. A first cold water pool, a first air cooler, and a first hot water pool are respectively provided between the first low-temperature heater and the third cooler.

[0030] refer to Figure 1 The first air cooler is located near the first cryogenic heater.

[0031] refer to Figure 1 The second cooler and the third cryogenic heater are connected by a second branch to form a closed loop. A cryogenic molten salt tank and a high-temperature molten salt tank are respectively provided between the second cooler and the third cryogenic heater. The setting of the cryogenic molten salt tank can realize the full temperature difference utilization and ensure that the temperature of the working medium at both ends of the cryogenic molten salt tank is equal. Furthermore, a second air cooler can also be set between the cryogenic molten salt tank and the third cryogenic heater.

[0032] refer to Figure 1 The second air cooler is located near the third cryogenic heater.

[0033] refer to Figure 1 The first cooler and the first low-temperature heater are connected by a third branch to form a closed loop. A second cold water pool, a third air cooler, and a second hot water pool are respectively provided between the first cooler and the first low-temperature heater.

[0034] refer to Figure 1 The third air cooler is located near the first cryogenic heater.

[0035] The operating mode of the system of this invention is as follows:

[0036] Energy storage section

[0037] Carbon dioxide is depressurized from the first low-pressure storage tank to state b through a throttling valve. A constant temperature source heats it to the corresponding saturation temperature, state c. After passing through a distributor, a portion of the fluid is heated to state f by the first cryogenic heater. The heating heat comes from the waste heat of the working fluid after its operation (i.e., the waste heat of xy, which is stored in the first hot water tank after energy release through heat storage. Then, during energy storage, the first cryogenic heater heats the incoming working fluid d). After heat exchange, the temperature of the hot water drops to the temperature corresponding to state L3, and then further drops to ambient temperature via the first air cooler. At this point, the water temperature is lowered to the ambient temperature, corresponding to state L1, and stored in... In the first cold water tank, a portion of the working fluid is compressed to state g by the compressor, and another portion is compressed to state h by the compressor. Then, from h to i, the working fluid is cooled to state i (the temperature of i and g is the same) by the second cooler (M1 (from the low-temperature molten salt tank) is cold molten salt, and M2 is high-temperature molten salt that has absorbed heat and is stored in the HST (high-temperature molten salt tank)). After passing through the mixer, the two working fluids, carbon dioxide i and g, merge and then pass through the first cooler (H1 is high-pressure cold water, and H2 is high-pressure hot water that has absorbed heat and is stored in the second hot water tank) to be cooled to the state corresponding to k and stored in the high-pressure gas storage tank.

[0038] Energy release section

[0039] During energy release, low-temperature, high-pressure carbon dioxide is released from the high-pressure storage tank. It first passes through the second low-temperature heater, where it is heated to the temperature corresponding to state point m (the heating heat is used to store the heat of compression in the second hot water tank). At point m, a portion of the carbon dioxide fluid (n) passes through a distributor and is heated by the high-temperature molten salt in the third low-temperature heater to the temperature corresponding to state o (the high-temperature molten salt comes from the temperature of state M3, which has been cooled through heat exchange and stored in the low-temperature molten salt tank). The arrangement of the low-temperature regenerator ensures that the carbon dioxide in the main energy release path and the carbon dioxide in the first energy release branch reach the same temperature before the inlet of the high-temperature regenerator, avoiding unnecessary... Losses increased efficiency;

[0040] A portion of the working fluid, after being split, passes through a low-temperature regenerator and is heated to the temperature corresponding to state point p by the processed working fluid. The working fluids corresponding to p and o converge at point q through a mixer, where the temperature and pressure are the same. Then, it passes through a high-temperature regenerator and is heated to the temperature corresponding to state point t by the processed carbon dioxide. From point t, it passes through the first high-temperature heater and is heated to the temperature corresponding to state point u. After heating, the carbon dioxide expands through the first turbine expander, changing its state to the state corresponding to state point v. Then, it is heated again through the second high-temperature heater and then expands through the second turbine expander (at which point the processing is complete). The processed carbon dioxide then passes through the regenerator, the high-temperature regenerator, and the low-temperature regenerator in sequence, until its temperature and pressure drop to the state corresponding to state point x. However, the working medium, carbon dioxide, still has usable residual heat at point x. Therefore, the residual heat at the end of the cycle is recovered using a third cooler (the recovered heat is stored in the first cold water tank and utilized during energy storage). The temperature of the carbon dioxide is reduced to the temperature corresponding to state point y, and the residual heat is stored in the first hot water tank and utilized during the recompression stage of energy storage. This can effectively reduce the absorption of heat from high-temperature heat sources, improve the system's cycle efficiency, and increase the energy storage density. Afterward, the carbon dioxide is cooled to saturated liquid by a constant-temperature cooler, corresponding to the temperature corresponding to state point z, and stored in the first low-pressure liquid storage tank. Thus, the energy storage cycle is completed.

[0041] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0042] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A waste heat utilization transcritical recompression carbon dioxide energy storage system, characterized in that, The system includes a first low-pressure liquid storage tank and a high-pressure gas tank interconnected to form a closed loop via a main energy storage pipeline and a main energy release pipeline, a first energy storage branch line on the main energy storage pipeline, and a first energy release branch line on the main energy release pipeline. A constant-temperature heater, a compressor, and a first cooler are sequentially arranged on the main energy storage pipeline away from the first low-pressure liquid storage tank. The two ends of the first energy storage branch line are respectively connected to the main energy storage pipeline between the constant-temperature heater and the compressor, and the main energy storage pipeline between the compressor and the first cooler. A first low-temperature heater, a re-compressor, and a second cooler are sequentially arranged on the first energy storage branch line away from the constant-temperature heater. The device includes, along the direction away from the high-pressure gas tank, a second cryogenic heater, a cryogenic regenerator, a high-temperature regenerator, a first high-temperature heater, a first turbine expander, a second high-temperature heater, a second turbine expander, a third cooler, and a constant-temperature cooler. The energy release main pipeline extends from the second turbine expander and then flows back through the high-temperature regenerator and the cryogenic regenerator in sequence. One end of the first energy release branch is connected to the energy release main pipeline between the second cryogenic heater and the cryogenic regenerator, and the other end is connected to the energy release main pipeline between the cryogenic regenerator and the high-temperature regenerator before the backflow. A third cryogenic heater is provided on the first energy release branch. The first low-temperature heater and the third cooler are connected through a first branch to form a closed loop. A first cold water pool, a first air cooler, and a first hot water pool are respectively provided between the first low-temperature heater and the third cooler. The second cooler and the third cryogenic heater are connected by a second branch to form a closed loop. A cryogenic molten salt tank, a second air cooler, and a third liquid storage tank are respectively provided between the second cooler and the third cryogenic heater. The first cooler and the first low-temperature heater are connected by a third branch to form a closed loop. A second cold water pool, a third air cooler, and a second hot water pool are respectively provided between the first cooler and the first low-temperature heater.

2. The waste heat utilization transcritical recompression carbon dioxide energy storage system according to claim 1, characterized in that, The first energy storage branch and the energy storage main branch, as well as the first energy release branch and the energy release main branch, are all connected by a splitter.

3. The waste heat utilization transcritical recompression carbon dioxide energy storage system according to claim 1, characterized in that, Both the constant temperature heater and the constant temperature cooler are connected to a constant temperature source.

4. The waste heat utilization transcritical recompression carbon dioxide energy storage system according to claim 1, characterized in that, A throttling valve is installed on the energy storage branch line between the constant temperature heater and the first low-pressure liquid storage tank.

5. A waste heat utilization transcritical recompression carbon dioxide energy storage system according to claim 1, characterized in that, The first air cooler is located near the first cryogenic heater.

6. A waste heat utilization transcritical recompression carbon dioxide energy storage system according to claim 1, characterized in that, The second air cooler is located near the third cryogenic heater.

7. A waste heat utilization transcritical recompression carbon dioxide energy storage system according to claim 1, characterized in that, The third air cooler is located near the first cryogenic heater.

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