Cold and heat storage type lightweight compressed gas energy storage power generation system

Abstract

The utility model provides a cold and heat storage type light compressed gas energy storage power generation system which comprises a compression pipeline and an expansion pipeline which are connected end to end and form circulation, and an internal heat exchanger is arranged between the compression pipeline and the expansion pipeline. The internal heat exchanger is used for pre-heating the compression pipeline during compression and pre-cooling the expansion pipeline during expansion; a compressor and a first heat exchanger are arranged on the compression pipeline, and the first heat exchanger is located at the rear end of the internal heat exchanger and connected with a heat storage tank. An expansion generator and a second heat exchanger are arranged on the expansion pipeline, and the second heat exchanger is located at the rear end of the internal heat exchanger and connected with a cold storage tank. The cold storage and heat storage type light-weight compressed gas energy storage power generation system is compact in structure, small in installation space, low in manufacturing and using cost, high in energy utilization rate and good in using effect.

Description

Technical Field

[0001] The utility model relates to a power generation system, in particular to a cold and heat storage type lightweight compressed gas energy storage power generation system. Background Art

[0002] Compressed air energy storage technology is a physical energy storage technology that uses compressed air to store energy. It has the advantages of large energy storage capacity, high safety, economy, environmental protection and mature technology. It plays an important role in the future energy system, especially in promoting the use of renewable energy and improving the stability of the power grid.

[0003] Carbon dioxide energy storage (CES) technology is a new physical energy storage technology based on compressed air energy storage (CAES) and Brayton power generation cycle. As a new technology, carbon dioxide energy storage uses a multi-stage compressor to convert atmospheric pressure gaseous carbon dioxide into high-pressure liquid carbon dioxide during the low electricity price period, and converts electrical energy into the form of carbon dioxide internal energy for storage; during the peak period of electricity consumption, the high-pressure liquid carbon dioxide is expanded and converted into atmospheric pressure gaseous carbon dioxide through a multi-stage expander to generate electricity, and finally realize the storage and release of electrical energy. However, this system has two disadvantages: ① The cost investment is huge. The whole system consists of low-pressure gas storage warehouse, high-pressure storage tank, compressor unit, turbine unit and heat exchange system. Since the low-pressure gas storage warehouse usually uses atmospheric pressure storage, the volume is very large, which invisibly increases the equipment cost and land cost. For safety, the high-pressure storage tank must have sufficient thickness, which will greatly increase the cost and difficulty of making the storage tank. The investment cost of these systems will be very huge, and the cost of technology promotion cannot be ignored; ② Low equipment utilization rate. The entire energy storage system usually uses the compressor to operate and store energy during the off-peak period, and the turbine generator to release energy during the peak period. Therefore, the compressor and turbine exist separately and operate in staggered periods. The entire system has a long operating time, a single set of equipment has a short operating time, and the overall equipment utilization rate is low, which invisibly increases the investment cost of the equipment. ③ The original energy storage system has a relatively fixed operating mechanism for different energy storage media, which has great limitations. Utility Model Content

[0004] [1] Technical issues to be solved

[0005] The technical problem to be solved by the utility model is to provide a cold and heat storage type lightweight compressed gas energy storage power generation system with compact structure, low manufacturing and use costs, small installation space and high equipment utilization rate.

[0006] 【2】Technical solutions to solve the problem

[0007] The utility model provides a cold and heat storage type lightweight compressed gas energy storage power generation system, which includes:

[0008] The compression pipeline and the expansion pipeline are connected end to end to form a cycle, and an internal heat exchanger 4 is provided between the compression pipeline and the expansion pipeline. The internal heat exchanger 4 is used to preheat the compression pipeline during compression and to pre-cool the expansion pipeline during expansion;

[0009] A compressor 3 and a first heat exchanger 51 are provided on the compression pipeline. The compressor 3 is located at the front end of the internal heat exchanger 4, and the first heat exchanger 51 is located at the rear end of the internal heat exchanger 4 and is connected to a heat storage tank 52. The heat storage tank 52 is connected to an external heat source and can collect and store the heat of the external heat source, and is used to heat the compression pipeline;

[0010] An expansion generator 6 and a second heat exchanger 21 are provided on the expansion pipeline. The expansion generator 6 is located at the front end of the internal heat exchanger 4, and the second heat exchanger 21 is located at the rear end of the internal heat exchanger 4 and is connected to a cold storage tank 22. The cold storage tank 22 is connected to a refrigeration unit and can store cold energy, and is used to cool the expansion pipeline.

[0011] Further, the medium in the compression pipeline and the expansion pipeline is a gas medium.

[0012] Further, the medium in the compression pipeline and the expansion pipeline is carbon dioxide or air or nitrogen.

[0013] Further, the main shafts of the compressor 3 and the expansion generator 6 are connected to each other and can operate synchronously.

[0014] Further, the medium in the compression pipeline is compressed by the compressor 3 to increase the temperature and pressure, and then enters the expansion pipeline after being heated successively by the internal heat exchanger 4 and the first heat exchanger 51.

[0015] Further, the medium in the expansion pipeline is expanded by the expansion generator 6 to decrease the temperature and pressure, and then enters the compression pipeline after being cooled successively by the internal heat exchanger 4 and the second heat exchanger 21.

[0016] Further, the compressor 3 is used to compress the medium from the state of temperature A and pressure a to the state of temperature B and pressure b. The internal heat exchanger 4 is used to increase the temperature of the medium from temperature B to temperature C. The first heat exchanger 51 is used to increase the temperature of the medium from temperature C to temperature D. Among them, the temperatures of A, B, C, and D increase in sequence, and the pressure a is less than the pressure b.

[0017] Further, the expansion generator 6 is used to expand the medium from the state of temperature D and pressure b to the state of temperature E and pressure a. The internal heat exchanger 4 is used to decrease the temperature of the medium from temperature E to temperature F. The second heat exchanger 21 is used to decrease the temperature of the medium from temperature F to temperature A. Among them, the temperatures of D, E, F, and A decrease in sequence, and the pressure b is greater than the pressure a.

[0018] Further, the expansion generator is a turbine expansion generator.

[0019] Further, the external heat source is the waste heat of the boiler.

[0020] Further, the gas at the intake end of the compression pipeline and the outlet end of the expansion pipeline is saturated gas.

[0021] 【3】Beneficial effects

[0022] The cold and heat storage type lightweight compressed gas energy storage power generation system of the present utility model subverts the traditional compressed air energy storage stored in the form of "high-pressure" potential energy and replaces it with a power storage mode with "cold and heat storage" as the storage method. It adopts a simpler storage mode, lower equipment investment cost, and more flexible combination method, improving the economic competitiveness of compressed gas energy storage. The main ways include the following three changes and highlights: by allowing the gas medium to circulate and operate synchronously within the entire system. First, the energy storage gas medium does not need to stay, canceling the low-pressure gas storage tank and high-pressure storage tank, greatly reducing the investment in storage tank equipment. Secondly, the compressor and the turbine expander can operate synchronously. Technically, the compressor and the turbine expander are coaxially arranged, reducing the cost of compression and expansion equipment; using the waste cold and waste heat generated by compression and expansion, preliminary heating and cooling are carried out through the regenerator, and finally, energy storage is carried out by using a refrigeration unit to store cold during the low electricity consumption period at night and the waste heat of the boiler to store heat, greatly reducing the difficulty of energy storage and effectively realizing the cascaded utilization of cold energy and heat energy; adopting the gas-gas conversion form, the cold and heat storage energy storage mode, with a variety of gas media, not limited to air and carbon dioxide, making the entire system have more possibilities; the cold and heat storage type lightweight compressed gas energy storage power generation system of the present utility model has a compact structure, small installation space, low manufacturing and use costs, high energy utilization rate, and good use effect. Description of the drawings

[0023] Figure 1 It is a schematic structural diagram of the cold and heat storage type lightweight compressed gas energy storage power generation system of the present utility model. Specific implementation manners

[0024] The following will introduce the embodiments of the present utility model in detail with reference to the drawings.

[0025] Refer to Figure 1 , the present utility model provides a cold and heat storage type lightweight compressed gas energy storage power generation system, including a compression pipeline and an expansion pipeline. The compression pipeline and the expansion pipeline are connected end to end to form a circulating pipeline. Refer to Figure 1, with the dashed line as the demarcation line, the upper part is the compression pipeline, and the lower part is the expansion pipeline. An internal heat exchanger 4 is provided between the compression pipeline and the expansion pipeline. The compression pipeline is connected to the first and second interfaces of the internal heat exchanger, and the expansion pipeline is connected to the third and fourth interfaces of the internal heat exchanger. This internal heat exchanger 4 is used to preheat the compression pipeline during compression and at the same time pre-cool the expansion pipeline during expansion to achieve internal heat exchange.

[0026] A compressor 3 and one or more first heat exchangers 51 are provided on the compression pipeline. Among them, the compressor 3 is located at the front end of the internal heat exchanger 4. Based on the air flow direction, the inlet end is the front and the outlet end is the rear, that is, flowing from front to back. The first heat exchanger 51 is located at the rear end of the internal heat exchanger 4. This first heat exchanger 51 is connected to a heat storage tank 52, and the heat storage tank 52 is connected to an external heat source, which is used to collect and store the heat of the external heat source. In this embodiment, the external heat source is a boiler. The first heat exchanger 51 can absorb the waste heat of the boiler and store it for heating the compression pipeline when the power generation system is working.

[0027] An expansion generator 6 and one or more second heat exchangers 21 are provided on the expansion pipeline. The expansion generator 6 is a turbine expansion generator, which is located at the front end of the internal heat exchanger 4. The second heat exchanger 21 is located at the rear end of the internal heat exchanger 4. This second heat exchanger 21 is connected to a cold storage tank 22, and the cold storage tank 22 is connected to a refrigeration unit, which can store cold energy for cooling the expansion pipeline when the power generation system is working.

[0028] In this application, the boiler (external heat source) and the refrigeration unit work at night with low electricity prices. That is, at night with low electricity prices, the cold storage tank is stored with cold energy, and the heat storage tank is stored with heat energy. And the power generation system works during the day with high electricity prices, thereby improving the energy utilization rate and reducing the use cost, and realizing the reasonable distribution of the two.

[0029] In this application, the media in the compression pipeline and the expansion pipeline are gas media. Therefore, there is no need for liquid storage tanks (high-pressure tanks, low-pressure tanks, etc.), reducing the installation space and the manufacturing, use and maintenance costs. The gas medium is carbon dioxide or air or nitrogen, or it can also be other gases.

[0030] In this embodiment, the main shafts of the compressor 3 and the expansion generator 6 are connected to each other and arranged coaxially, which can achieve synchronous operation, and thus can reduce the costs of the compression and expansion equipment.

[0031] During operation, the medium in the compression pipeline is compressed by the compressor 3, then heated and pressurized, and enters the expansion pipeline after being heated successively by the internal heat exchanger 4 and the first heat exchanger 51; the medium in the expansion pipeline is expanded by the expansion generator 6, then cooled and depressurized, and enters the compression pipeline after being cooled successively by the internal heat exchanger 4 and the second heat exchanger 21, forming a cycle of compression and expansion.

[0032] Specifically, the compressor 3 is used to compress the medium from the state of temperature A and pressure a to the state of temperature B and pressure b. The temperature B is higher than the temperature A, and the pressure b is higher than the pressure a. That is, after being compressed by the compressor, both the temperature and pressure of the medium increase. The internal heat exchanger 4 is used to increase the temperature of the medium from temperature B to temperature C, and the pressure remains unchanged during this process. The first heat exchanger 51 is used to increase the temperature of the medium from temperature C to temperature D, and the pressure remains unchanged during this process. Among them, the temperatures A, B, C, and D increase in sequence, and the pressure a is less than the pressure b. In this embodiment, the pressure a is 2 Mpa - 3 Mpa, the pressure b is 6 Mpa - 8 Mpa, the temperature A is -20°C to -8°C, the temperature B is 60°C to 70°C, the temperature C is 100°C to 120°C, and the temperature D is 190°C to 210°C; the expansion generator 6 is used to expand the medium from the state of temperature D and pressure b to the state of temperature E and pressure a. The temperature E is lower than the temperature D, and the pressure a is lower than the pressure b. That is, after being expanded by the expansion generator, both the temperature and pressure decrease. The internal heat exchanger 4 is used to decrease the temperature of the medium from temperature E to temperature F, and the pressure remains unchanged during this process. The second heat exchanger 21 is used to decrease the temperature of the medium from temperature F to temperature A, and the pressure remains unchanged during this process. Among them, the temperatures D, E, F, and A decrease in sequence, and the pressure b is greater than the pressure a. In this embodiment, the pressure a is 2 Mpa - 3 Mpa, the pressure b is 6 Mpa - 8 Mpa, the temperature A is -20°C to -8°C, the temperature D is 190°C to 210°C, the temperature E is 110°C to 125°C, and the temperature F is 60°C to 80°C, thereby forming a gas-gas cycle.

[0033] In this application, the gas at the inlet end of the compression pipeline (i.e., the inlet end of the compressor) and the outlet end of the expansion pipeline (i.e., the outlet end of the second heat exchanger) is saturated gas. The inlet end of the compression pipeline is connected to the outlet end of the expansion pipeline to form a cycle, that is, the gas in the first pipeline 101 is saturated gas. Saturated gas refers to the steam in a dynamic equilibrium state. At a certain temperature, when liquid evaporates, molecules escape from the liquid surface to form steam, and at the same time, there are also molecules returning from the steam to the liquid. When these two processes reach dynamic equilibrium, the macroscopic evaporation stops, and this kind of steam is called saturated steam.

[0034] The following is a detailed description of this embodiment:

[0035] It includes a first pipeline 101, a compressor 3, a second pipeline 102, an internal heat exchanger 4 (the first and second interfaces), a third pipeline 103, a first heat exchanger 51, a fourth pipeline 104, an expansion generator 6, a fifth pipeline 105, an internal heat exchanger 4 (the third and fourth interfaces), a second heat exchanger 21 and the first pipeline 101 (the same as above), forming a circulation pipeline. The first pipeline 101 contains 2.5 Mpa low-temperature and low-pressure gaseous CO2, and the gas in the first pipeline 101 is a saturated gas. It is compressed by the compressor to form 7 Mpa medium-temperature and high-pressure gaseous CO2 and enters the second pipeline. The 7 Mpa medium-temperature and high-pressure gaseous CO2 in the second pipeline is heated by the internal heat exchanger to form 7 Mpa high-pressure and medium-high-temperature gaseous CO2 and enters the third pipeline. The 7 Mpa high-pressure and medium-high-temperature gaseous CO2 in the third pipeline is heated again through heat exchange in the heat storage tank to form 7 Mpa high-pressure and high-temperature gaseous CO2 and enters the fourth pipeline. The above is the compression pipeline; the 7 Mpa high-pressure and high-temperature gaseous CO2 in the fourth pipeline generates electricity through the turbine expansion generator and forms 2.5 Mpa low-pressure and medium-high-temperature gaseous CO2 and enters the fifth pipeline. The 2.5 Mpa low-pressure and medium-high-temperature gaseous CO2 in the fifth pipeline is cooled by the internal heat exchanger to form 2.5 Mpa low-pressure and medium-temperature gaseous CO2 and enters the sixth pipeline. The 2.5 Mpa low-pressure and medium-temperature gaseous CO2 in the sixth pipeline is cooled again through cold energy exchange in the second heat exchanger to form 2.5 Mpa low-pressure and low-temperature gaseous CO2 and enters the first pipeline. The above is the expansion pipeline, thus completing the entire cycle process. During the period of low electricity prices at night, the refrigeration unit uses low-cost electricity for refrigeration and heat storage, and stores the cold energy in the cold storage tank. At the same time, it collects the waste heat of the boiler and stores the heat energy in the heat storage tank, finally completing the energy storage process of cold storage and heat storage.

[0036] The above internal heat exchanger plays a role in heating during the compression process and cooling during the expansion process, effectively utilizing the cascade utilization of its cold energy and heat energy. In the entire cycle process, it finally realizes the cold storage and heat storage process during the low electricity consumption peak period at night and the power generation process from compression to expansion during the high electricity consumption peak period during the day.

[0037] The energy storage and heat storage lightweight compressed gas energy storage power generation system of the present utility model subverts the traditional compressed air energy storage that stores in the form of "high-pressure" potential energy and replaces it with an energy storage mode of "energy storage and heat storage". It adopts a simpler storage mode, lower equipment investment cost, and more flexible combination method to improve the economic competitiveness of compressed gas energy storage. The main ways include the following three changes and highlights: The gas medium circulates and operates synchronously within the entire system. First, the energy storage gas medium does not need to stay, eliminating the low-pressure gas storage bin and high-pressure storage tank, greatly reducing the investment in storage tank equipment. Second, the compressor and turbine expander can operate synchronously. Technically, the compressor and turbine expander are coaxial, reducing the cost of compression and expansion equipment. The waste cold and waste heat generated by compression and expansion are initially heated and cooled through a recuperator. Finally, energy storage is carried out by using a refrigeration unit to store cold energy during the low electricity consumption period at night and the waste heat of the boiler to store heat, greatly reducing the difficulty of energy storage and effectively realizing the cascade utilization of cold energy and heat energy. The gas-gas conversion form and the energy storage and heat storage energy storage mode are adopted, and the gas medium is diverse, not limited to air and carbon dioxide, making the entire system have more possibilities. The energy storage and heat storage lightweight compressed gas energy storage power generation system of the present utility model is compact in structure, small in installation space, low in manufacturing and use costs, high in energy utilization rate, and good in use effect.

[0038] The above are only the preferred embodiments of the present utility model. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the technical principle of the present utility model, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present utility model.

Claims

1. A cold and heat storage type lightweight compressed gas energy storage power generation system, characterized in that: include: A compression pipeline and an expansion pipeline connected end to end to form a cycle, an internal heat exchanger is provided between the compression pipeline and the expansion pipeline, the internal heat exchanger is used to pre-heat the compression pipeline during compression and to pre-cool the expansion pipeline during expansion; The compression pipeline is provided with a compressor and a first heat exchanger, the compressor is located at the front end of the internal heat exchanger, the first heat exchanger is located at the rear end of the internal heat exchanger and is connected to a heat storage tank, the heat storage tank is connected to an external heat source and can collect and store heat from the external heat source, and is used to heat the compression pipeline; An expansion generator and a second heat exchanger are provided on the expansion pipeline. The expansion generator is located at the front end of the internal heat exchanger. The second heat exchanger is located at the rear end of the internal heat exchanger and is connected to a cold storage tank. The cold storage tank is connected to the refrigeration unit and can store cold energy and is used to cool the expansion pipeline.

2. The cold and heat storage lightweight compressed gas energy storage power generation system according to claim 1, characterized in that: The medium in the compression pipeline and the expansion pipeline is a gas medium.

3. The cold and heat storage lightweight compressed gas energy storage power generation system according to claim 1 or 2, characterized in that: The medium in the compression pipeline and the expansion pipeline is carbon dioxide, air or nitrogen.

4. The cold and heat storage type lightweight compressed gas energy storage power generation system according to claim 1, characterized in that: The main shafts of the compressor and the expansion generator are connected to each other and can realize synchronous operation.

5. The cold and heat storage type lightweight compressed gas energy storage power generation system according to claim 1, characterized in that: The medium in the compression pipeline is compressed by the compressor, and then the temperature and pressure of the medium are increased. The medium is heated in the internal heat exchanger and the first heat exchanger in sequence, and then enters the expansion pipeline.

6. The cold and heat storage type lightweight compressed gas energy storage power generation system according to claim 1, characterized in that: The medium in the expansion pipeline is cooled and depressurized after expansion by the expansion generator, and enters the compression pipeline after being cooled in sequence by the internal heat exchanger and the second heat exchanger.

7. The cold and heat storage type lightweight compressed gas energy storage power generation system according to claim 5, characterized in that: The compressor is used to compress the medium from the A temperature and a pressure state to the B temperature and b pressure state, the internal heat exchanger is used to raise the medium temperature from B to C, and the first heat exchanger is used to raise the medium temperature from C to D, wherein the A temperature, B temperature, C temperature and D temperature increase in sequence, and the a pressure is less than the b pressure.

8. The cold and heat storage type lightweight compressed gas energy storage power generation system according to claim 6, characterized in that: The expansion generator is used to expand the medium from the D temperature and b pressure state to the E temperature and a pressure state, the internal heat exchanger is used to reduce the medium from the E temperature to the F temperature, and the second heat exchanger is used to reduce the medium from the F temperature to the A temperature, wherein the D temperature, the E temperature, the F temperature and the A temperature decrease in sequence, and the b pressure is greater than the a pressure.

9. The cold and heat storage type lightweight compressed gas energy storage power generation system according to claim 1, characterized in that: The expansion generator is a turbine expansion generator.

10. The cold and heat storage type lightweight compressed gas energy storage power generation system according to claim 1, characterized in that: The gas at the air inlet end of the compression pipeline and the air outlet end of the expansion pipeline is saturated gas.

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