Ocean underwater compressed air energy storage combined cooling heating and power system

Abstract

The invention relates to the technical field of renewable energy power generation distribution and storage, in particular to an ocean underwater compressed air energy storage combined cooling heating and power system which comprises a compressor unit, an expansion unit, an ORC power generation system, a hot water tank, a cold water tank and an air storage tank. The compressor unit is connected with the hot water tank and the ORC power generation system. The air storage tank is connected with the expansion unit, the expansion unit is further connected with the hot water tank, and the hot water tank is further connected with the cold water tank; the compressor unit comprises at least two stages of compressors, and the expansion unit comprises at least two stages of expansion machines. The multi-stage compression and multi-stage expansion equipment is adopted for energy storage and energy release, compared with the prior art, the effect of configuring an efficient, large-capacity and low-cost energy storage facility is achieved, and the problem that the efficient, large-capacity and low-cost energy storage facility needs to be configured urgently due to rapid expansion of the offshore renewable energy power generation installation scale is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of renewable energy power generation and energy storage, and particularly to a marine underwater compressed air energy storage combined cooling, heating and power supply system. Background Art

[0002] In recent years, the installed capacity of offshore renewable energy power generation in China has increased rapidly, especially offshore wind power. Due to the inherent intermittency and instability of renewable energy, with the rapid increase in the installed scale, it has become extremely urgent to equip corresponding energy storage facilities.

[0003] For the energy storage of marine renewable energy power generation, there are two methods: onshore energy storage and offshore energy storage. Onshore energy storage means transmitting the electric energy to land and then storing it. For example, compressed air energy storage in the form of storage tanks, compressed air energy storage in rock caves or mine pits, battery energy storage, etc. The best way for offshore energy storage is marine underwater compressed air energy storage, which can cleverly utilize the hydrostatic pressure of seawater to achieve constant-pressure energy storage and energy release. The system operates efficiently and has a high energy storage density. Compressed air energy storage in onshore storage tank mode has a small scale and high costs. Compressed air energy storage in onshore rock cave or mine pit mode is difficult to site and cannot match large-scale offshore renewable energy power generation. Battery energy storage currently cannot achieve high-capacity, high-efficiency and low-cost. Compared with onshore energy storage, the storage tank of marine underwater compressed air energy storage is located underwater, and the internal air pressure is equal to the external hydrostatic pressure, so the pressure borne by the storage tank is greatly reduced, and it does not occupy surface and onshore space, and can be naturally integrated with offshore wind power and photovoltaic power generation geographically. In addition, offshore energy storage can meet the dispatching requirements of the power grid, enable more offshore renewable energy power generation to be connected to the grid, and can efficiently utilize expensive offshore cables.

[0004] The marine renewable energy power generation and energy storage system requires both an operation and maintenance platform and an energy storage and energy release platform. These platforms need cooling and heating during operation and maintenance to maintain the safe operation of equipment and the comfort of personnel, and the underwater compressed air energy storage system can both generate electricity and provide cooling and heating for floating platforms. Based on this, the present application proposes a marine underwater compressed air energy storage combined cooling, heating and power supply system. Summary of the Invention

[0005] The object of the present invention is to provide a marine underwater compressed air energy storage combined cooling, heating and power supply system to solve the problems existing in the prior art.

[0006] To solve the problems existing in the prior art, the present invention adopts the following technical solutions:

[0007] Advantages of the Present Invention

[0008] 1. The present invention uses multi-stage compression and multi-stage expansion equipment for energy storage and energy release. Compared with the prior art, it achieves the effect of configuring an energy storage facility with high efficiency, large capacity, and low cost, and solves the problem that with the rapid expansion of the installed capacity of offshore renewable energy power generation, there is an urgent need to configure an energy storage facility with high efficiency, large capacity, and low cost.

[0009] 2. In view of the fact that the inter-stage compression heat is greater than the heat required to heat the air at the inlet of the expansion machine, in order to efficiently utilize this part of the compression heat, the present invention configures an organic Rankine power generation system and uses surface seawater as the cold source. The heat supply for the offshore floating platform uses the inter-stage compression heat, and the cold supply uses the air at the outlet of the intermediate-stage expansion machine for re-expansion refrigeration.

[0010] 3. The present invention utilizes an underwater open air storage tank to efficiently utilize the hydrostatic pressure to achieve constant-pressure storage and constant-pressure release of air, improving the performance of the expansion machine and the compressor and the energy recovery efficiency of the entire system.

[0011] 4. The offshore underwater compressed air energy storage and offshore floating platform solve the instability of offshore wind power and offshore photovoltaic power and the problem of large-scale energy storage configuration. Moreover, the present invention can be arranged near offshore wind power or offshore photovoltaic power, and at the same time realizes the efficient utilization of the synergy of energy in the air (wind power or photovoltaic power), on the water (the ORC power generation device uses surface seawater as the power generation cold source), and underwater (hydrostatic pressure). BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic structural diagram of the present invention.

[0013] Description of the reference numerals: 1 - first-stage compressor; 2 - first-stage cooler; 3 - second-stage compressor; 4 - second-stage cooler; 5 - third-stage compressor; 6 - third-stage cooler; 7 - air storage tank inlet valve; 8 - air storage tank air release valve; 9 - first-stage heater; 10 - first-stage expansion machine; 11 - second-stage heater; 12 - second-stage expansion machine; 13 - third-stage heater; 14 - third-stage expansion machine; 15 - refrigeration expansion machine inlet valve; 16 - hot water pump for heater; 17

[0014] - hot water tank; 18 - cold water tank; 19 - cold water pump; 20 - hot water pump for heat supply; 21 - heat supply heat exchanger; 22 - hot water pump for ORC; 23 - evaporator; 24 - ORC expansion machine; 25 - ORC circulation pump; 26 - ORC condenser; 27 - seawater pump; 28 - refrigeration expansion machine; 29 - refrigeration heat exchanger; 30 – floating platform; 31 - seawater; 32 - air storage tank. DETAILED DESCRIPTION OF THE INVENTION

[0015] To make the objectives, technical solutions, and beneficial effects of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0016] As Figure 1 shown, an ocean underwater compressed air energy storage combined cooling, heat, and power supply system includes a compressor unit, an expander unit, an ORC power generation system, a hot water tank 17, a cold water tank 18, and an air storage tank 32;

[0017] The compressor unit is respectively connected to the hot water tank 17 and the ORC power generation system; the air storage tank 32 is connected to the expander unit, and the expander unit is also connected to the hot water tank 17, and the hot water tank 17 is also connected to the cold water tank 18; the compressor unit includes at least two-stage compressors, and the expander unit includes at least two-stage expanders;

[0018] When the power demand is at a low ebb, the compressors in the compressor unit compress, releasing inter-stage compression heat. The inter-stage compression heat is recovered by water, and the water is stored in the hot water tank 17; at the same time, the inter-stage compression heat supplies heat to the ORC power supply system.

[0019] When the power demand is at a peak, the air in the air storage tank 32 is released to drive the expander unit to do work, and the hot water tank 17 heats up the expander unit; the water in the hot water tank 17 is stored in the cold water tank 18 after passing through the expander unit.

[0020] In the present invention, since the compressor unit includes at least two-stage compressors, when the compressors compress, they release inter-stage compression heat. The inter-stage compression heat is recovered by water, raising the temperature of the water to become hot water, which is stored in the hot water tank 17. Additionally, considering that the inter-stage compression heat is greater than the heat required to heat the air at the inlet of the expander, to efficiently utilize this part of the compression heat, an ORC power generation system is configured. The inter-stage compression heat supplies heat to the ORC power supply system, and then the ORC power supply system generates electricity.

[0021] When the power demand is at a low ebb, under the action of the compressor unit, electrical energy is converted into high-pressure air and stored in the air storage tank 32, achieving the effect of heat storage.

[0022] When the power demand is at a peak, the air stored in the air storage tank 32 is released, driving the expander to do work and converting the pressure energy of the air into electrical energy. Preferably, the air storage tank 32 is an underwater air storage tank 32, which stores high-pressure air.

[0023] Moreover, since the temperature of the compressed air entering the expander for work is relatively low and its work capacity is poor, the air in the air storage tank 32 can be heated by the water in the hot water tank 17 to increase the temperature and enthalpy value and enhance the work capacity. After heating the air, the temperature of the water decreases and it is stored in the cold water tank 18.

[0024] The above-mentioned at least two-stage compressor can be a compressor that completes compression in multiple stages, with one or several cylinders in each stage, or can be multiple compressors of different stages. In the present invention, multiple compressors of different stages are taken as an example for illustration.

[0025] In some embodiments of the present invention, the marine underwater compressed air energy storage combined cooling, heating and power supply system further includes a floating platform 30, which is respectively connected to the compressor unit, and the inter-stage compression heat supplies heat to the floating platform 30.

[0026] Specifically, when the floating platform 30 needs cooling capacity, the low-temperature air before the last-stage expander is introduced into the refrigeration expander for expansion refrigeration, and the system does not require electric energy to drive the refrigerator. In addition, since the recovered inter-stage compression heat of the compressor is more than the heat required to heat the inlet air of the expander, this part of the surplus heat can be used as a heat source. On the one hand, it can meet the heat energy demand of the floating platform 30, and on the other hand, it can supply heat to the ORC power supply system to enable the ORC power supply system to generate electricity.

[0027] In some embodiments of the present invention, a cooler is correspondingly connected to the outlet end of each stage of the compressor; a heater is connected to the outlet end of each stage of the expander. In the compressor unit, since a cooler is correspondingly connected to the outlet end of each different-stage compressor, the temperature of the compressed hot air can be balanced by the cooler to avoid danger caused by excessive temperature. Moreover, the air entering the next-stage compressor can be slightly cooled down, which can improve the compression efficiency in the next-stage compressor. In the expander unit, since a heater is correspondingly connected to the outlet end of each expander, after the temperature of the compressed air entering the expander for work, the compressed air is heated by the heater to balance the temperature of the compressed air, increase the temperature and enthalpy value, enhance the work capacity, and improve the efficiency of the expander.

[0028] Furthermore, the floating platform 30 is also connected to the expander unit. The expander unit includes multiple stages of expanders. The low-temperature air before the last-stage expander is introduced into the refrigeration expander for expansion refrigeration, and the cooling capacity obtained by refrigeration is used by the floating platform 30.

[0029] In some embodiments of the present invention, the ORC power supply system includes an evaporator 23, an ORC expander 24, an ORC condenser 26, and an ORC circulation pump 25 connected in sequence; the inlet of the water side of the evaporator 23 is connected to the hot water pump 22 for ORC, and the outlet of the water side is connected to the cold water tank 18; the inlet of the water side of the ORC condenser 26 is connected to the seawater 31 pump 27, and the outlet is connected to the drainage pipeline. In the present invention, surface seawater 31 is used as the cold source, and the intermediate-stage compression heat of the compressor unit is used as the heat source.

[0030] In some embodiments of the present invention, the air storage tank 32 is an underwater air storage tank 32. The underwater air storage tank 32 can be suspended at a certain depth underwater, fixed by an anchoring system, or placed on the seabed by a counterweight, and the air storage tank 32 is a cylindrical storage tank with an open bottom. By using the underwater open-type air storage tank 32, the hydrostatic pressure is efficiently utilized to achieve constant-pressure storage and release of air, improving the performance of the expander and compressor and the energy recovery efficiency of the entire system.

[0031] In some embodiments of the present invention, the marine underwater compressed air energy storage combined cooling, heating and power supply system is arranged near offshore wind power or offshore photovoltaic, and the three cooperate with each other. Specifically, the marine underwater compressed air energy storage and the offshore floating platform 30 solve the instability and large-scale energy storage problems of offshore wind power and offshore photovoltaic, and the present invention can be arranged near offshore wind power or offshore photovoltaic, simultaneously realizing the efficient utilization of energy in the air (offshore wind power or offshore photovoltaic), on the water (the equipment in the ORC power generation system uses surface seawater 31 as the power generation cold source), and underwater (hydrostatic pressure).

[0032] In some embodiments of the present invention, the floating platform 30 is also equipped with a heating heat exchanger 21, and the heating heat exchanger 21 is connected to the hot water tank 17.

[0033] In the present invention, an example is given where the compressor unit includes a first-stage compressor 1, a second-stage compressor 3, and a third-stage compressor 5, the expander unit includes a first-stage expander 10, a second-stage expander 12, and a third-stage expander 14, and correspondingly connected are a first-stage cooler 2, a second-stage cooler 4, a third-stage cooler 6, a first-stage heater 9, a second-stage heater 11, and a third-stage heater 13.

[0034] Specifically, the inlet end of the first-stage compressor 1 is connected to the outside atmosphere, and the high-pressure outlet is sequentially connected to the first-stage cooler 2, the second-stage compressor 3, the second-stage cooler 4, the third-stage compressor 5, and the third-stage cooler 6. The high-pressure and low-temperature air discharged from the outlet end of the third-stage cooler 6 is filled into the underwater air storage tank 32 through the air storage tank inlet valve 7.

[0035] After the water in the cold water tank 18 is pressurized by the cold water pump 19, it is divided into three paths of cold water, which are respectively connected to the first-stage cooler 2, the second-stage cooler 4, and the third-stage cooler 6. The water passing through the three coolers becomes hot water, and the three paths of hot water converge and enter the hot water tank 17.

[0036] The air storage tank 32 is connected to the first-stage heater 9 through the gas storage tank air release valve 8.

[0037] The air inlet of the first-stage expander 10 is connected to the first-stage heater 9, and the air outlet of the first-stage expander 10 is successively connected to the second-stage heater 11 and the second-stage expander 12. The air outlet of the second-stage expander 12 is divided into two paths. One path is connected to the third-stage heater 13, and the other path is connected to the refrigeration expander inlet valve 15. Moreover, the air inlet of the third-stage expander 14 is connected to the third-stage heater 13, and the air outlet of the third-stage expander 14 is connected to the outside atmosphere.

[0038] The first-stage heater 9, the second-stage heater 11, and the third-stage heater 13 all include an air end and a water inlet and outlet end. Taking the first-stage heater 9 as an example, the inlet of its air end is connected to the air storage tank 32 through the gas storage tank air release valve 8, and the outlet of its air end is successively connected to the first-stage expander 10, the second-stage heater 11, the second-stage expander 12, the third-stage heater 13, and the third-stage expander 14; the water inlet and outlet ends of the first heater respectively include a water inlet end and a water outlet end. The water inlet end is connected to the hot water tank 17 through the hot water pump for heating, and the water outlet end enters the cold water tank 18.

[0039] The refrigeration expander inlet valve 15 is connected to the air inlet of the refrigeration expander 28, and the air outlet of the refrigeration expander 28 is connected to the refrigeration heat exchanger 29.

[0040] Furthermore, the water outlet of the hot water tank 17 is divided into three paths, which are respectively connected to the hot water pump for heater 16, the hot water pump for heating 20, and the hot water pump for ORC 22. And the hot water pump for heating 20 is also connected to the heating heat exchanger 21, and the heating heat exchanger 21 is also connected to the cold water tank 18. That is, the hot water tank 17 is connected to the ORC power supply system through the hot water pump for ORC 22.

[0041] Since the cooling heat released between compressor stages is greater than the heat required for heating the expander inlet, efficiently utilizing this part of the remaining heat to drive the ORC system for power generation can improve the system energy recovery efficiency and reduce the investment payback period.

[0042] In addition, the low-temperature air at the outlet of the second-stage expander 12 can be expanded again for direct refrigeration. Compared with compression refrigeration, only one more refrigeration expander 28 needs to be added, without the need to purchase a complete set of compression refrigeration equipment, and no electric energy is consumed, providing cooling capacity for the floating platform 30. If the floating platform 30 needs heat energy, hot water can be directly led out from the hot water tank 17 and enter the heating heat exchanger 21 for heat energy extraction.

[0043] As a specific embodiment of the present invention, the compressed air energy storage system has a power of 400 MW and a capacity of 1000 MWh, and the underwater air storage tank 32 is placed 800 meters deep underwater.

[0044] Three-stage compression and three-stage expansion equipment are adopted for energy storage and energy release.

[0045] When the power demand is at a low ebb, the normal temperature and pressure air is pressurized by the compressor, the inter-stage temperature rises to 180 °C, after being cooled by cold water, the air temperature becomes 55 °C, and the water temperature rises to 165 °C. The 165 °C hot water enters the hot water tank 17 for storage, and the air with a temperature of 55 °C and a pressure of 8.0 MPa is filled into the underwater air storage tank 32, realizing the storage of electric energy.

[0046] When the power demand is at a peak, the underwater air storage tank 32 releases high-pressure air for power generation; the air before entering the expander is heated by the hot water in the hot water tank 17 to reach 150 °C, and then enters the expander to expand and do work. Due to heating the air, the hot water temperature drops from 165 °C to 50 °C, and then is stored in the cold water tank 18.

[0047] Since the inter-stage cooling heat of the compressor is more than the heat required to heat the air entering the expander, the remaining 165 °C hot water is used to drive the ORC device for power generation. The driving heat source of the ORC device is the 165 °C hot water, and the cold source is the surface seawater 31 at the ambient temperature.

[0048] The air temperature at the outlet of the second-stage expander 12 is 40 °C. If the system needs cooling capacity, a part of this air can be drawn out for further expansion for refrigeration.

[0049] If the system needs heat energy, a part of the hot water can be drawn from the 165 °C hot water tank 17 to provide it.

[0050] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Claims

1. An ocean underwater compressed air energy storage combined cooling, heating and power supply system, characterized in that, It includes a compressor unit, an expander unit, an ORC power generation system, a hot water tank, a cold water tank and an air storage tank; The compressor unit is respectively connected to the hot water tank and the ORC power generation system; the air storage tank is connected to the expander unit, and the expander unit is also connected to the hot water tank, and the hot water tank is also connected to the cold water tank; the compressor unit includes a compressor with at least two stages, and the expander unit includes an expander with at least two stages; When the power demand is at a low ebb, the compressor in the compressor unit compresses, releases the inter-stage compression heat, recovers the inter-stage compression heat through water, and the water is stored in the hot water tank; at the same time, the inter-stage compression heat supplies heat to the ORC power supply system; When the power demand is at a peak, the air in the air storage tank is released to drive the expander unit to do work, and the hot water tank heats up the expander unit; the water in the hot water tank is stored in the cold water tank after passing through the expander unit.

2. The marine underwater compressed air energy storage combined cooling, heating and power supply system according to claim 1, characterized in that The marine underwater compressed air energy storage combined cooling, heat and power supply system further includes a floating platform, the floating platform is respectively connected to the compressor unit, and the inter-stage compression heat supplies heat to the floating platform.

3. The marine underwater compressed air energy storage combined cooling, heating and power supply system according to claim 1, wherein The outlet end of each stage of the compressor is correspondingly connected with a cooler; the outlet end of each stage of the expander is connected with a heater.

4. The marine underwater compressed air energy storage combined cooling, heating and power supply system according to claim 3, characterized in that, The floating platform is also connected to the expander unit, and the expander unit includes multiple stages of expanders. The low-temperature air before the last stage of the expander is introduced into a refrigeration expander for expansion refrigeration, and the cold quantity obtained by refrigeration is used by the floating platform.

5. The marine underwater compressed air energy storage combined cooling, heating and power supply system according to claim 3, wherein The floating platform is also equipped with a heat supply heat exchanger, and the heat supply heat exchanger is connected to the hot water tank.

6. The marine underwater compressed air energy storage combined cooling, heat and power supply system according to claim 1, wherein The ORC power supply system includes an evaporator, an ORC expander, an ORC condenser and an ORC circulation pump connected in sequence; The inlet of the water side of the evaporator is connected to the hot water pump for ORC, and the outlet of the water side is connected to the cold water tank; the inlet of the water side of the ORC condenser is connected to the seawater pump, and the outlet is connected to the drainage pipeline.

7. The marine underwater compressed air energy storage combined cooling, heating and power supply system according to claim 1, wherein, The air storage tank is an underwater air storage tank, and the underwater air storage tank can float at a certain depth underwater, be fixed by an anchoring system, or be placed on the seabed by a counterweight, and the air storage tank is a cylindrical storage tank with an open bottom.

8. The marine underwater compressed air energy storage combined cooling, heating and power supply system according to claim 1, characterized in that, The marine underwater compressed air energy storage combined cooling, heat and power supply system is arranged near offshore wind power or offshore photovoltaic, and the three cooperate with each other.

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