Graded heat storage system and power generation system

Abstract

The invention discloses a graded heat storage system and a power generation system. The graded heat storage system comprises a gas storage; the plurality of compressors connected in series are connected with the gas storage; the expansion machines are arranged corresponding to the compressors and connected with one another, and the expansion machines are connected with the gas storage; the multiple first heat storage devices are arranged corresponding to the compressors, inlets of the first heat storage devices are connected with the corresponding compressors, outlets of the first heat storage devices are connected with the corresponding expansion machines, and the multiple first heat storage devices are provided with different preset storage temperatures; the gas storage, the compressor, the first heat storage device and the expansion machine form a circulation system. By means of the mode, different kinds of heat generated by the multi-stage compressor can be stored respectively, high-quality heat and low-quality heat are prevented from being mixed, and the high-quality heat can be reserved and effectively utilized.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed air energy storage, and in particular to a hierarchical heat storage system and a power generation system. Background Art

[0002] Compressed air energy storage technology is a method of energy storage that converts electrical energy into compressed air potential energy for storage and then expands the compressed air to release energy when needed. Traditional solutions use multi-stage compression to reduce energy consumption, and during the compression process, the heat generated by compression is recovered through a heat exchanger to preheat the gas in the subsequent expansion process. However, under normal circumstances, the actual operating pressure ratio and outlet temperature of each compressor stage are not consistent, and traditional systems often only have a unified heat storage tank for heat storage, resulting in the mixing of high-quality heat and low-quality heat generated by different compression stages. This mixing dilutes the high-temperature, high-quality heat, thereby reducing the efficiency of heat utilization and causing waste of high-quality heat.

[0003] Furthermore, compressors at different stages are limited by various factors, resulting in different maximum compression ratios. This also leads to significantly different temperatures of compressed air during the compression process at different stages. Using a single heat storage device prevents the effective utilization of these widely varying heat levels. Summary of the Invention

[0004] In response to the above problems, the present invention provides a hierarchical heat storage system and a power generation system to at least solve some of the problems in the prior art.

[0005] According to a first aspect of the present invention, a hierarchical heat storage system is provided, comprising a gas storage reservoir, a plurality of compressors connected in series, a plurality of expanders connected in series, and a plurality of first heat storage devices. The plurality of compressors are connected to the gas storage reservoir; a plurality of expanders are disposed correspondingly to the compressors and are interconnected, and the plurality of expanders are connected to the gas storage reservoir; a plurality of first heat storage devices are disposed correspondingly to the compressors, with inlets of the first heat storage devices connected to corresponding compressors, and outlets of the first heat storage devices connected to corresponding expanders, and the plurality of first heat storage devices are configured with different preset storage temperatures; the gas storage reservoir, the compressors, the first heat storage devices, and the expanders form a circulation system.

[0006] Through the above method, different first heat storage devices are used to store different amounts of heat generated by multiple compressors, avoiding the mixing of high-quality heat and low-quality heat, preventing the dilution of high-quality heat, thereby reducing the waste of high-quality heat and facilitating the retention and effective use of high-quality heat.

[0007] Optionally, the compressors are provided with different levels, and the preset storage temperature of the first heat storage device corresponds to the level of the corresponding connected compressor.

[0008] In the above manner, compressors of different levels are matched with first heat storage devices of different preset storage temperatures, so as to facilitate hierarchical heat storage.

[0009] Optionally, the graded heat storage system further includes a plurality of first heat exchangers, which are arranged corresponding to the compressors, the first ends of the first heat exchangers are connected to the outlets of the compressors, and the second ends of the first heat exchangers are connected to the inlets of the corresponding first heat storage devices, for recovering the heat generated by the compressors of the corresponding levels.

[0010] In the above manner, the gas at the compressor outlet is received by the first heat exchanger and transported to the corresponding first heat storage device for storage, thereby facilitating efficient recovery of heat generated by compressors of different levels.

[0011] Optionally, the graded heat storage system further includes a plurality of second heat exchangers, which are arranged corresponding to the expanders, the first ends of the second heat exchangers are connected to the outlets of the corresponding first heat storage devices, and the second ends of the second heat exchangers are connected to the inlets of the corresponding expanders, to ensure that the compressed air is sufficiently preheated before entering the expanders.

[0012] In the above manner, the gas with different heat contents in the first heat storage device is transported to the expander through the second heat exchanger, so as to facilitate targeted preheating according to different quality heat, which is beneficial to subsequent expansion by the expander.

[0013] Optionally, the multiple compressors are set with different pressure ratios, and the pressure ratios correspond to the levels.

[0014] In the above manner, the compression ratio of the compressor corresponds to the level, making it easy to distinguish the compression ratio.

[0015] Optionally, the outlet temperatures of multiple compressors vary in a gradient to meet different heat storage requirements.

[0016] Through the above method, it is easy to increase the compressor outlet temperature step by step, and generate heat of different temperatures and different qualities step by step.

[0017] Optionally, the hierarchical heat storage system further comprises a second heat storage device, the inlet of which is connected to the second heat exchanger, and the outlet of which is connected to the first heat exchanger.

[0018] In the above manner, the second heat storage device is used to connect the second heat exchanger at the expander and the first heat exchanger at the compressor, so that the gas expanded by the expander can be further transported to the compressor to form a cycle.

[0019] A second aspect of the present invention provides a power generation system comprising the above-mentioned hierarchical heat storage system.

[0020] Through the above method, electrical energy is converted into compressed air potential energy and stored in grades according to temperature and quality. The air is preheated according to the different quality heat, and the temperature of the air before expansion is gradually increased. When needed, the compressed air is expanded through the expander to release energy, thereby improving the power generation efficiency of the expanders at all levels and improving the working efficiency of the overall power generation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of a hierarchical heat storage system according to an embodiment of the present invention.

[0022] Reference numerals:

[0023] 100. Hierarchical heat storage system; 1. Gas storage. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. Figure 1 A hierarchical thermal storage system 100 according to an embodiment of the present invention is described.

[0026] <Hierarchical Thermal Storage System 100>

[0027] Figure 1 FIG is a structural diagram of a hierarchical heat storage system 100 according to an embodiment of the present invention. Figure 1 The first embodiment of the present invention provides a hierarchical heat storage system 100, comprising a gas storage reservoir 1, three compressors connected in series, three expanders connected in series, and three first heat storage devices.

[0028] The three compressors connected in series are C1, C2, and C3 from left to right; the three expanders connected in series are T1, T2, and T3 from left to right; and the three first heat storage devices are HOT1, HOT2, and HOT3 from top to bottom. The three first heat storage devices are connected in parallel, and the compressors, expanders, and first heat storage devices are all arranged in parallel. Gas storage 1 is used to supply and store gas. Compressor C3 is connected to gas storage 1, and expander T1 is connected to gas storage 1. The three expanders are connected to the three compressors. The three first heat storage devices are arranged in parallel with the three compressors. The inlets of the first heat storage devices are connected to the corresponding compressors, and the outlets of the first heat storage devices are connected to the corresponding expanders. That is, C1, HOT1, and T1 are connected in sequence, C2, HOT2, and T2 are connected in sequence, and C3, HOT3, and T3 are connected in sequence. The three first heat storage devices HOT1, HOT2, and HOT3 are set with different preset storage temperatures. Gas storage 1, the compressors, the first heat storage devices, and the expanders form a circulation system.

[0029] It should be noted that the embodiment of the present invention does not limit the number of compressors, expanders and first heat storage devices, as long as they correspond to each other.

[0030] Through the above method, different first heat storage devices are used to store different amounts of heat generated by multiple compressors, avoiding the mixing of high-quality heat and low-quality heat, preventing the dilution of high-quality heat, thereby reducing the waste of high-quality heat and facilitating the retention and effective use of high-quality heat.

[0031] The quality of heat in the present invention corresponds to factors such as the level of the compressor, the pressure ratio and the outlet temperature. Figure 1 The components of the hierarchical heat storage system 100 in the embodiment of the present invention are described.

[0032] <Compressor>

[0033] Continue to refer Figure 1 The three compressors C1, C2 and C3 connected in series are set with different levels. For example, C1 is a first-stage compressor, C2 is a second-stage compressor, and C3 is a third-stage compressor. The preset storage temperature of the first heat storage device corresponds to the level of the corresponding connected compressor, that is, the preset storage temperature of HOT1 corresponds to the level of C1, the preset storage temperature of HOT2 corresponds to the level of C2, and the preset storage temperature of HOT3 corresponds to the level of C3.

[0034] In the above manner, the outlets of the compressors are connected to separate first heat storage devices through independent heat exchangers, and compressors of different levels are corresponded to first heat storage devices with different preset storage temperatures, which facilitates graded heat storage.

[0035] like Figure 1 As shown, the three compressors are set with different pressure ratios, which correspond to their levels. The compressor has an inlet temperature, which can be 55°C. Different pressure ratios can produce different outlet temperatures. For example, the pressure ratios of multiple compressors are set in ascending order according to the level, that is, the pressure ratio of the first-stage compressor C1 is lower than the pressure ratio of the second-stage compressor C2, and the pressure ratio of the second-stage compressor C2 is lower than the pressure ratio of the third-stage compressor C3. Taking a system that needs to compress to 9 MPa as an example, the pressure ratio of the first-stage compressor C1 can be between 1-1.5, the pressure ratio of the second-stage compressor C2 can be between 1.5-7.03, and the pressure ratio of the third-stage compressor can be greater than 7.03. For example, the pressure ratio of C1 is 1.25, the pressure ratio of C2 is 4.48, and the pressure ratio of C3 is 8.

[0036] In other embodiments, the pressure ratios of the multiple compressors are set to decrease in order of levels. The present invention does not limit the setting method of the pressure ratio.

[0037] In the above manner, the compression ratio of the compressor corresponds to the level, making it easy to distinguish the compression ratio.

[0038] Furthermore, as the pressure ratios of the three compressors are set to increase sequentially, the outlet temperatures of the three compressors also increase sequentially. The outlet temperatures of the three compressors can vary in a gradient to meet different heat storage requirements. That is, the outlet temperature of the first-stage compressor C1 is relatively low (low temperature), corresponding to the storage in the first heat storage device HOT1 with a relatively low temperature; the outlet temperature of the second-stage compressor C2 is moderate (medium temperature), corresponding to the storage in the first heat storage device HOT2 with a moderate temperature; and the outlet temperature of the third-stage compressor C3 is relatively high (high temperature), corresponding to the storage in the first heat storage device HOT3 with a relatively high temperature.

[0039] Through the above method, it is easy to increase the compressor outlet temperature step by step, and generate heat of different temperatures and different qualities step by step.

[0040] <First Heat Storage Device>

[0041] refer to Figure 1The first heat storage devices HOT1, HOT2, and HOT3 can be heat storage tanks. The heat storage tanks contain heat storage medium, and the preset storage temperature of the heat storage tanks can be the temperature of the heat storage medium. For example, the heat storage medium temperature of HOT1 can be 100°C (i.e., low temperature), the heat storage medium temperature of HOT2 can be between 100-300°C (i.e., medium temperature), and the heat storage medium temperature of HOT3 can be less than 300°C (i.e., high temperature). The preset storage temperature of the heat storage tanks matches the outlet temperature of the corresponding level of compressor. Taking into account the heat loss of the heat storage medium during transportation, the preset storage temperature of the first heat storage device can be slightly lower than the outlet temperature of the compressor. For example, the outlet temperature of the secondary compressor is 180°C, and the corresponding preset storage temperature of the first heat storage device HOT2 is 170°C. The outlet temperature can be the outlet air temperature, realizing hierarchical heat storage.

[0042] <First Heat Exchanger>

[0043] like Figure 1 As shown, the hierarchical heat storage system 100 also includes three first heat exchangers HX1, HX2, and HX3, which are arranged corresponding to the compressors. The three first heat exchangers are spaced apart from the compressors and connected in series with the three compressors. The first ends of the first heat exchangers are connected to the outlets of the compressors, and the second ends of the first heat exchangers are connected to the inlets of the corresponding first heat storage devices, which are used to recover heat generated by the compressors at the corresponding levels. In other words, C1, HX1, and HOT1 are connected in sequence; C2, HX2, and HOT2 are connected in sequence; and C3, HX3, and HOT3 are connected in sequence.

[0044] In the above manner, the gas at the compressor outlet is received by the first heat exchanger and transported to the corresponding first heat storage device for storage, thereby facilitating efficient recovery of heat generated by compressors of different levels.

[0045] <Second Heat Exchanger>

[0046] like Figure 1 As shown, the hierarchical heat storage system 100 may also include three second heat exchangers HX4, HX5, and HX6, which are arranged corresponding to the expanders. The first ends of the second heat exchangers are connected to the outlets of the corresponding first heat storage devices, and the second ends of the second heat exchangers are connected to the inlets of the corresponding expanders, to ensure that the compressed air is fully preheated before entering the expanders. In other words, HOT1, HX4, and T1 are connected in sequence, HOT2, HX5, and T2 are connected in sequence, and HOT3, HX6, and T3 are connected in sequence.

[0047] In the above manner, the gas with different heat contents in the first heat storage device is transported to the expander through the second heat exchanger, so as to facilitate targeted preheating according to different quality heat, gradually increase the temperature of the air before expansion, facilitate expansion by subsequent expanders, improve the power generation efficiency of expanders at each level, and thus improve the working efficiency of the overall hierarchical heat storage system 100.

[0048] <Expander>

[0049] like Figure 1 As shown, throttle valves (not shown) can be respectively provided on the expanders T1, T2 and T3 to adjust and control the flow rate or pressure of the internal expansion medium (air).

[0050] <Second Heat Storage Device>

[0051] like Figure 1 As shown, the hierarchical heat storage system 100 further includes a second heat storage device COLD. The temperature of the second heat storage device COLD is lower than the preset storage temperature of any of the first heat storage devices (i.e., HOT1, HOT2, and HOT3). Second heat exchangers HX4, HX5, and HX6 are connected in parallel to the inlet of the second heat storage device COLD. First heat exchangers HX1, HX2, and HX3 are connected in parallel to the outlet of the second heat storage device COLD.

[0052] In the above manner, the second heat storage device COLD is used to connect the three second heat exchangers at the expander and the three first heat exchangers at the compressor, so that the gas expanded by the expander can be further transported to the compressor to form a cycle.

[0053] <Power Generation System>

[0054] like Figure 1 As shown, the second embodiment of the present invention provides a power generation system including the aforementioned hierarchical heat storage system 100. This configuration can convert electrical energy into compressed air potential energy and store it in a hierarchical manner according to temperature and quality. Different quality heat is then preheated, gradually increasing the temperature of the air before expansion. When necessary, the compressed air is expanded through expanders to release energy, thereby improving the power generation efficiency of each expander and, therefore, the overall efficiency of the power generation system.

[0055] The working process of the hierarchical heat storage system 100 in the embodiment of the present invention is described below.

[0056] In the compression stage, the three compressors C1, C2 and C3 connected in series with the gas storage reservoir 1 respectively obtain air from the gas storage reservoir 1. The three compressors C1, C2 and C3 of different levels compress the air and convert electrical energy into compressed air potential energy.

[0057] During the storage phase, first heat exchangers HX1, HX2, and HX3, connected to compressors C1, C2, and C3, respectively, recover heat generated when the compressors compress air. C1 has a lower heat content than C2, which in turn has a lower heat content than C3. This means that the heat recovered by HX1, HX2, and HX3 increases in order: low-temperature heat, medium-temperature heat, and high-temperature heat, respectively. First heat exchangers HX1, HX2, and HX3 store the recovered heat in their three connected first heat storage devices. The low-temperature heat in HX1 is stored in HOT1, the medium-temperature heat in HX2 is stored in HOT2, and the high-temperature heat in HX3 is stored in HOT3.

[0058] During the expansion and discharge phase, the first heat storage devices HOT1, HOT2, and HOT3 transport the heat storage medium to the second heat exchangers HX4, HX5, and HX6, respectively. The three expanders T1, T2, and T3 are connected to the second heat exchangers HX4, HX5, and HX6, respectively, which can gradually increase the temperature of the air before expansion, thereby improving the power generation efficiency of the expanders at each level, thereby improving the working efficiency of the overall hierarchical heat storage system 100.

[0059] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A hierarchical heat storage system, characterized in that: include: gas storage; A plurality of compressors connected in series are connected to the gas storage; A plurality of expanders connected in series are arranged corresponding to the compressors and connected to each other, and the plurality of expanders are connected to the gas storage; a plurality of first heat storage devices, arranged corresponding to the compressors, wherein the inlets of the first heat storage devices are connected to the corresponding compressors, and the outlets of the first heat storage devices are connected to the corresponding expanders, and the plurality of first heat storage devices are set with different preset storage temperatures; The gas storage, the compressor, the first heat storage device and the expander form a circulation system.

2. The hierarchical heat storage system according to claim 1, characterized in that: The compressors are provided with different levels, and the preset storage temperature of the first heat storage device corresponds to the level of the correspondingly connected compressor.

3. The hierarchical heat storage system according to claim 2, characterized in that: Also includes: Multiple first heat exchangers are arranged corresponding to the compressors, the first ends of the first heat exchangers are connected to the outlets of the compressors, and the second ends of the first heat exchangers are connected to the inlets of the corresponding first heat storage devices, for recovering the heat generated by the compressors corresponding to the levels.

4. The hierarchical heat storage system according to claim 3, characterized in that: Also includes: Multiple second heat exchangers are arranged corresponding to the expanders, the first ends of the second heat exchangers are connected to the outlets of the corresponding first heat storage devices, and the second ends of the second heat exchangers are connected to the inlets of the corresponding expanders, so as to ensure that the compressed air is fully preheated before entering the expanders.

5. The hierarchical heat storage system according to claim 2, characterized in that: The plurality of compressors are set at different pressure ratios, and the pressure ratios correspond to the levels.

6. The hierarchical heat storage system according to claim 5, characterized in that: The outlet temperatures of the multiple compressors vary in a gradient to meet different heat storage requirements.

7. The hierarchical heat storage system according to claim 4, characterized in that: Also includes: A second heat storage device, wherein an inlet of the second heat storage device is connected to the second heat exchanger, and an outlet of the second heat storage device is connected to the first heat exchanger.

8. A power generation system, characterized in that: It comprises a hierarchical heat storage system as described in any one of claims 1 to 7.

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