A compressed co2 energy storage system and method based on ground flare heat recovery
By using a circulation system of heat transfer oil tank and gas-liquid heat exchanger, the waste heat of flue gas from the ground flare is used to heat the heat transfer oil, which solves the problem of unstable heat utilization in the compressed CO2 energy storage system and improves system efficiency and the gasification effect of liquid CO2.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CNPC JICHAI POWER EQUIP
- Filing Date
- 2024-12-12
- Publication Date
- 2026-06-12
AI Technical Summary
The waste heat generated by the ground flare is difficult to utilize stably, which leads to a decrease in the efficiency of the compressed CO2 energy storage system, and the heat of liquid CO2 phase change is difficult to preserve.
By setting up a circulation system of heat transfer oil tank and gas-liquid heat exchanger, the waste heat of flue gas from the ground flare is used to heat the heat transfer oil, control the temperature of the heat transfer oil, provide the heat required for the vaporization of liquid CO2, and form a circulation in the compressed CO2 energy storage unit to achieve stable heat recovery and utilization.
The efficiency of the compressed CO2 energy storage unit has been improved, the problem of unstable heat source caused by unstable combustion load of ground flare has been solved, and stable gasification and energy storage cycle of liquid CO2 have been realized.
Smart Images
Figure CN122191048A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of compressed carbon dioxide energy storage technology, and relates to a compressed CO2 energy storage system and method based on heat recovery from a ground flare. Background Technology
[0002] Compressed carbon dioxide (CO2) energy storage is a physical energy storage technology. During storage, an electric motor drives a compressor to compress CO2 at room temperature and pressure into a liquid state, storing the heat of compression. In the energy release process, the liquid CO2 vaporizes, absorbing the stored heat to drive a turbine and generate electricity. Because the liquefaction process is relatively low-temperature, the heat generated by the CO2 phase change is often difficult to retain, leading to a decrease in the efficiency of the compressed CO2 energy storage system. Additional heat can be introduced to improve efficiency. Due to its low phase change temperature, the required energy grade for this process is also relatively low.
[0003] A surface flare is a special combustion facility used to handle combustible and toxic gases and vapors that cannot be recovered or reprocessed in oil and gas fields, petrochemical plants, refineries, chemical plants, and other factories or facilities. A surface flare generates a large amount of waste heat during combustion, but due to the high uncertainty of its combustion load, it is difficult to increase the grade of usable waste heat while ensuring stable operation, thus making it difficult to utilize. Summary of the Invention
[0004] This invention provides a compressed CO2 energy storage system and method based on heat recovery from a ground flare. It combines a ground flare with compressed CO2 energy storage technology, utilizes a controllable flue gas recovery pipeline, uses the temperature of a heat transfer oil storage tank as a judgment condition to achieve heat recovery, and then provides the heat required for the gasification of liquid CO2 through high-temperature heat transfer oil.
[0005] To achieve the above objectives, the present invention adopts the following technical solution.
[0006] In a first aspect, the present invention provides a compressed CO2 energy storage system based on heat recovery from a ground-based flare, the compressed CO2 energy storage system comprising a ground-based flare, a gas-liquid heat exchanger, a thermal oil cooling tank, a thermal oil heating tank, and a compressed CO2 energy storage unit; the compressed CO2 energy storage unit comprising a CO2 evaporator, a CO2 expander, a CO2 compressor, and a CO2 liquefaction unit; wherein...
[0007] A flue gas bypass pipe is opened on one side of the ground flare, and the flue gas bypass pipe is connected to the air inlet of the gas-liquid heat exchanger.
[0008] The inlet of the gas-liquid heat exchanger is connected to the heat transfer oil cooling tank via a pipeline; the outlet of the gas-liquid heat exchanger is connected to the heat transfer oil cooling tank, and the heat transfer oil cooling tank is connected to the inlet of the CO2 evaporator of the compressed CO2 energy storage unit; the outlet of the CO2 evaporator is connected to the heat transfer oil cooling tank.
[0009] The inlet of the gas-liquid heat exchanger is also connected to the heat transfer oil tank via a pipeline.
[0010] This invention maintains the temperature of the heat transfer oil in the heat transfer oil tank within a reasonable range and is unaffected by the unstable load of the ground flare. By setting up a separate circulation between the heat transfer oil tank and the gas-liquid heat exchanger, and using a temperature sensor to monitor the temperature of the heat transfer oil in the heat transfer oil tank, the circulation between the heat transfer oil tank and the gas-liquid heat exchanger is determined based on the temperature of the heat transfer oil.
[0011] As an optional implementation, in the compressed CO2 energy storage unit, a CO2 evaporator, a CO2 expander, a CO2 compressor, a CO2 liquefier, and a CO2 evaporator are connected in sequence. This sequential connection of the CO2 evaporator, CO2 expander, CO2 compressor, CO2 liquefier, and CO2 evaporator forms a cycle of liquid CO2 self-evaporation, expansion, compression, liquefaction, and re-evaporation, enabling continuous compressed CO2 energy storage.
[0012] As an optional implementation, the compressed CO2 energy storage system also includes a control system.
[0013] As an optional implementation, a valve is installed on the flue gas bypass pipe to control the flue gas entering the ground vent flare of the gas-liquid heat exchanger.
[0014] As an optional implementation, a valve is installed on the flue gas bypass duct, and the opening and closing of the valve is controlled by the control system.
[0015] As an optional implementation, the compressed CO2 energy storage system based on ground flare heat recovery also includes a flue gas discharge pipeline, and the outlet of the gas-liquid heat exchanger is connected to the flue gas pipeline.
[0016] As an optional implementation, a temperature sensor is installed in the heat transfer oil tank to monitor the temperature of the heat transfer oil in the heat transfer oil tank.
[0017] As an optional implementation, the temperature of the high-temperature heat transfer oil is 50-60°C.
[0018] As an optional implementation, the temperature of the low-temperature heat transfer oil is below 48°C.
[0019] In this invention, when the temperature of the heat transfer oil in the heat transfer oil tank is low (below 48°C), the low-temperature heat transfer oil in the heat transfer oil tank is transported to the gas-liquid heat exchanger, where it is heated to 50-60°C using the waste heat of the flue gas.
[0020] Secondly, the present invention provides a compressed CO2 energy storage method based on heat recovery from a ground-based flare, wherein the compressed CO2 energy storage is performed using the aforementioned compressed CO2 energy storage system based on heat recovery from a ground-based flare; the compressed CO2 energy storage method includes the following steps:
[0021] (1) The flue gas from the ground flare enters the gas-liquid heat exchanger through the flue gas bypass pipe, heats the low-temperature heat transfer oil from the heat transfer oil cold tank to obtain high-temperature heat transfer oil, and stores it in the heat transfer oil hot tank.
[0022] (2) The high-temperature heat transfer oil in the heat transfer oil tank is transported to the CO2 evaporator of the compressed CO2 energy storage unit. The high-temperature heat transfer oil exchanges heat with the liquid CO2 in the CO2 evaporator, causing the liquid CO2 to evaporate into gaseous CO2. The compressed CO2 energy is stored in the compressed CO2 energy storage unit after expansion, compression, and liquefaction. The temperature of the high-temperature heat transfer oil decreases to obtain low-temperature heat transfer oil, which is then stored in the low-temperature heat transfer oil tank.
[0023] (3) Repeat steps (1) and (2) to make the low-temperature heat transfer oil undergo a heat exchange cycle from gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in CO2 evaporator → low-temperature heat transfer oil → gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in CO2 evaporator; at the same time, make the liquid CO2 undergo cyclic energy storage of evaporation, expansion, compression, liquefaction and re-evaporation in the compressed CO2 energy storage unit, so as to realize the use of flue gas waste heat for compressed CO2 energy storage.
[0024] As an optional implementation, the compressed CO2 energy storage method further includes step (4), which includes the following steps:
[0025] When the temperature of the heat transfer oil in the heat transfer oil tank decreases, the heat transfer oil in the heat transfer oil tank is transported to the gas-liquid heat exchanger, and the heat transfer oil from the heat transfer oil tank is heated by the high-temperature flue gas to obtain high-temperature heat transfer oil, which is then stored in the heat transfer oil tank.
[0026] As an optional implementation, when the temperature of the heat transfer oil in the heat transfer oil tank is below 48°C, the operation of step (4) is performed.
[0027] As an optional implementation, the temperature of the high-temperature heat transfer oil is 50-60°C.
[0028] As an optional implementation, the temperature of the low-temperature heat transfer oil is below 48°C.
[0029] As an optional implementation, the compressed CO2 energy storage method includes the following steps:
[0030] (1) Use the control system to open the valve of the flue gas bypass pipe of the ground venting torch, and the flue gas through the flue gas bypass pipe enters the gas-liquid heat exchanger to heat the low temperature heat transfer oil from the heat transfer oil cold tank. After raising the temperature of the heat transfer oil to 50-60℃, it is stored in the heat transfer oil hot tank.
[0031] (2) The high-temperature heat transfer oil in the heat transfer oil hot tank is transported to the CO2 evaporator of the compressed CO2 energy storage unit. The high-temperature heat transfer oil provides heat for the vaporization of liquid CO2, thereby causing it to vaporize. In the compressed CO2 energy storage unit, the compressed CO2 is expanded, compressed, and liquefied. After the high-temperature heat transfer oil completes heat exchange in the CO2 evaporator, it is cooled to 35°C to become low-temperature heat transfer oil. The low-temperature heat transfer oil is then transported to the heat transfer oil cold tank.
[0032] (3) Repeat steps (1) and (2) to make the cycle of low-temperature heat transfer oil → gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in CO2 evaporator → low-temperature heat transfer oil → gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in CO2 evaporator possible; at the same time, make the liquid CO2 evaporate, expand, compress, liquefy and re-evaporate in the compressed CO2 energy storage unit in a cycle to realize the continuous operation of compressed CO2 energy storage by utilizing the waste heat of flue gas;
[0033] (4) When the temperature of the heat transfer oil in the heat transfer oil tank is lower than 48°C, open the valve of the flue gas bypass pipe to introduce the flue gas into the gas-liquid heat exchanger, and at the same time pump the heat transfer oil in the heat transfer oil tank into the gas-liquid heat exchanger to raise the temperature of the heat transfer oil to 50-60°C.
[0034] In this invention, the above-mentioned technical features can be freely combined to form new technical solutions without conflict with each other.
[0035] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:
[0036] (1) The compressed CO2 energy storage system based on heat recovery from ground venting flare according to the present invention uses the waste heat of flue gas from the ground venting flare to provide the heat required for the vaporization of liquid CO2 to the compressed CO2 energy storage unit, thereby improving the efficiency of the compressed CO2 energy storage unit; at the same time, it effectively utilizes the waste heat of flue gas generated by the ground venting flare.
[0037] (2) The compressed CO2 energy storage system based on ground venting torch heat recovery according to the present invention utilizes the characteristic that the vaporization temperature of liquid CO2 is close to room temperature to reduce the temperature of heat transfer oil storage and reduce the difficulty of extracting waste heat.
[0038] (3) The compressed CO2 energy storage system based on ground venting flare heat recovery according to the present invention solves the problem of unstable combustion load of ground venting flare and inability to provide a stable heat source by setting up a separate heat transfer oil tank and a gas-liquid heat exchanger, using the temperature of heat transfer oil in the heat transfer oil tank as the judgment basis, and adjusting and maintaining the temperature of heat transfer oil in the heat transfer oil tank at any time. Attached Figure Description
[0039] Figure 1 This is a schematic diagram of a compressed CO2 energy storage system based on heat recovery from a ground-based flare, according to the present invention. Detailed Implementation
[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.
[0041] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.
[0042] Example 1
[0043] A compressed CO2 energy storage system based on heat recovery from a ground flare includes a ground flare, a gas-liquid heat exchanger, a thermal oil cold tank, a thermal oil hot tank, and a compressed CO2 energy storage unit; the compressed CO2 energy storage unit includes a CO2 evaporator, a CO2 expander, a CO2 compressor, and a CO2 liquefaction unit.
[0044] Specifically, in the compressed CO2 energy storage unit, the CO2 evaporator, CO2 expander, CO2 compressor, CO2 liquefier and CO2 evaporator are connected in sequence to form a cycle of liquid CO2 self-evaporation, expansion, compression, liquefaction and re-evaporation. Specifically, the outlet of the CO2 evaporator is connected to the inlet of the CO2 expander, the outlet of the CO2 expander is connected to the inlet of the CO2 compressor, the outlet of the CO2 compressor is connected to the inlet of the CO2 liquefier, and the outlet of the CO2 liquefier is connected to the inlet of the CO2 evaporator.
[0045] The exhaust chimney of the surface flare in the oil and gas field is modified by installing a flue gas bypass pipe on one side of the flare and a valve controlled by a control system. This bypass pipe connects to the inlet of a gas-liquid heat exchanger, whose outlet connects to a thermal oil tank. The thermal oil tank connects to the inlet of the CO2 evaporator in the compressed CO2 energy storage unit, and the CO2 evaporator outlet connects to a thermal oil cooler. The inlet of the gas-liquid heat exchanger is connected to both the thermal oil cooler and the thermal oil tank via pipelines, and the outlet of the gas-liquid heat exchanger is connected to the flue gas pipeline. A temperature sensor is installed in the thermal oil tank to monitor the temperature of the thermal oil.
[0046] The compressed CO2 energy storage system based on heat recovery from a surface flare provided in this embodiment utilizes the waste heat of flue gas discharged from the flue gas bypass pipeline of the oil and gas field surface flare to heat the low-temperature heat transfer oil entering the gas-liquid heat exchanger to obtain high-temperature heat transfer oil. The high-temperature heat transfer oil is stored in a heat transfer oil tank and then transported to a CO2 evaporator. The high-temperature heat transfer oil provides heat for the liquid CO2 to evaporate into CO2 gas, thereby enabling the liquid CO2 to cycle through evaporation, expansion, compression, liquefaction, and re-evaporation in the compressed CO2 energy storage unit. This utilizes the waste heat of the flue gas to compensate for the problem of reduced efficiency of the compressed CO2 energy storage unit caused by the difficulty in retaining the heat generated by the CO2 phase change during the energy release process, thus improving the efficiency of the compressed CO2 energy storage unit.
[0047] After the heat from the high-temperature heat transfer oil entering the CO2 evaporator is absorbed, the oil temperature decreases, becoming low-temperature heat transfer oil. This low-temperature oil is then transported from the liquid outlet of the CO2 evaporator to a heat transfer oil cold tank, and then to a gas-liquid heat exchanger to reabsorb waste heat from the flue gas, becoming high-temperature heat transfer oil again. This forms a heat recycling process: low-temperature heat transfer oil → gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in the CO2 evaporator → low-temperature heat transfer oil → gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in the CO2 evaporator. The low-temperature heat transfer oil initially entering the gas-liquid heat exchanger can come from low-temperature heat transfer oil stored in either the heat transfer oil cold tank or the heat transfer oil hot tank.
[0048] Example 2
[0049] A compressed CO2 energy storage method based on heat recovery from a ground-based flare is disclosed, employing the compressed CO2 energy storage system based on heat recovery from a ground-based flare provided in Example 1 for compressed CO2 energy storage; the compressed CO2 energy storage method includes the following steps:
[0050] S1: The control system opens the valve of the flue gas bypass pipe of the ground flare, allowing the flue gas to enter the gas-liquid heat exchanger. This heats the low-temperature heat transfer oil from the cold tank, raising its temperature to 50-60°C before storing it in the hot tank. The hot tank contains a temperature sensor. When the temperature of the hot tank drops below 48°C, the control system opens the valve of the flue gas bypass pipe, introducing the flue gas into the gas-liquid heat exchanger. Simultaneously, the heat transfer oil in the hot tank is pumped into the gas-liquid heat exchanger, raising its temperature back to 50-60°C.
[0051] S2: The high-temperature heat transfer oil in the heat transfer oil hot tank enters the CO2 evaporator of the compressed CO2 energy storage unit. The high-temperature heat transfer oil provides heat to the liquid CO2 for vaporization, thereby causing it to vaporize. In the compressed CO2 energy storage unit, the compressed CO2 is expanded, compressed, and liquefied for energy storage. After the high-temperature heat transfer oil completes heat exchange in the CO2 evaporator, it is cooled to 35°C to become low-temperature heat transfer oil. This low-temperature heat transfer oil is then transported to the heat transfer oil cold tank.
[0052] S3: Repeat steps S1 and S2 to ensure that the cycle of low-temperature heat transfer oil → gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in CO2 evaporator → low-temperature heat transfer oil → gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in CO2 evaporator is carried out; at the same time, liquid CO2 is evaporated, expanded, compressed, liquefied, and re-evaporated in the compressed CO2 energy storage unit to realize the continuous operation of compressed CO2 energy storage by utilizing the waste heat of flue gas.
Claims
1. A compressed CO2 energy storage system based on heat recovery from a ground-based flare, characterized in that, The compressed CO2 energy storage system includes a ground flare, a gas-liquid heat exchanger, a thermal oil cooling tank, a thermal oil heating tank, and a compressed CO2 energy storage unit; the compressed CO2 energy storage unit includes a CO2 evaporator, a CO2 expander, a CO2 compressor, and a CO2 liquefaction unit; wherein... A flue gas bypass pipe is opened on one side of the ground flare, and the flue gas bypass pipe is connected to the air inlet of the gas-liquid heat exchanger. The inlet of the gas-liquid heat exchanger is connected to the heat transfer oil cooling tank via a pipeline; the outlet of the gas-liquid heat exchanger is connected to the heat transfer oil cooling tank, the heat transfer oil cooling tank is connected to the inlet of the CO2 evaporator; and the outlet of the CO2 evaporator is connected to the heat transfer oil cooling tank. The inlet of the gas-liquid heat exchanger is also connected to the heat transfer oil tank via a pipeline.
2. The compressed CO2 energy storage system based on heat recovery from a ground-based flare as described in claim 1, characterized in that, The compressed CO2 energy storage system also includes a control system.
3. The compressed CO2 energy storage system based on heat recovery from a ground-based flare as described in claim 1, characterized in that, A valve is installed on the flue gas bypass pipe to control the flue gas entering the ground vent flare of the gas-liquid heat exchanger.
4. The compressed CO2 energy storage system based on heat recovery from a ground-based flare as described in claim 2, characterized in that, A valve is installed on the flue gas bypass duct, and the opening and closing of the valve is controlled by the control system.
5. The compressed CO2 energy storage system based on heat recovery from a ground-based flare according to any one of claims 1-4, characterized in that, A temperature sensor is installed in the heat transfer oil tank to monitor the temperature of the heat transfer oil in the tank.
6. A compressed CO2 energy storage method based on heat recovery from a ground-based flare, characterized in that, The compressed CO2 energy storage method employs a compressed CO2 energy storage system based on heat recovery from a ground-based flare, as described in any one of claims 1-5, to store compressed CO2 energy. The compressed CO2 energy storage method includes the following steps: (1) The flue gas from the ground flare enters the gas-liquid heat exchanger through the flue gas bypass pipe, heats the low-temperature heat transfer oil from the heat transfer oil cold tank to obtain high-temperature heat transfer oil, and stores it in the heat transfer oil hot tank. (2) The high-temperature heat transfer oil in the heat transfer oil tank is transported to the CO2 evaporator of the compressed CO2 energy storage unit. The high-temperature heat transfer oil exchanges heat with the liquid CO2 in the CO2 evaporator, causing the liquid CO2 to evaporate into gaseous CO2. The compressed CO2 energy is stored in the compressed CO2 energy storage unit after expansion, compression, and liquefaction. The temperature of the high-temperature heat transfer oil decreases to obtain low-temperature heat transfer oil, which is then stored in the low-temperature heat transfer oil tank. (3) Repeat steps (1) and (2) to make the low-temperature heat transfer oil undergo a heat exchange cycle from gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in CO2 evaporator → low-temperature heat transfer oil → gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in CO2 evaporator; at the same time, make the liquid CO2 undergo cyclic energy storage of evaporation, expansion, compression, liquefaction and re-evaporation in the compressed CO2 energy storage unit, so as to realize the use of flue gas waste heat for compressed CO2 energy storage.
7. The compressed CO2 energy storage method based on heat recovery from a ground-based flare as described in claim 6, characterized in that, The compressed CO2 energy storage method further includes step (4), which includes the following steps: When the temperature of the heat transfer oil in the heat transfer oil tank decreases, the heat transfer oil in the heat transfer oil tank is transported to the gas-liquid heat exchanger, and the heat transfer oil from the heat transfer oil tank is heated by the high-temperature flue gas to obtain high-temperature heat transfer oil, which is then stored in the heat transfer oil tank.
8. The compressed CO2 energy storage method based on heat recovery from a ground-based flare as described in claim 7, characterized in that, When the temperature of the heat transfer oil in the heat transfer oil tank is below 48°C, perform the operation of step (4).
9. The compressed CO2 energy storage method based on heat recovery from a ground-based flare according to any one of claims 6-8, characterized in that, The temperature of the high-temperature heat transfer oil is 50-60℃, and the temperature of the low-temperature heat transfer oil is below 48℃.
10. The compressed CO2 energy storage method based on heat recovery from a ground-based flare as described in claim 6, characterized in that, The compressed CO2 energy storage method includes the following steps: (1) Use the control system to open the valve of the flue gas bypass pipe of the ground venting torch, and the flue gas through the flue gas bypass pipe enters the gas-liquid heat exchanger to heat the low temperature heat transfer oil from the heat transfer oil cold tank. After raising the temperature of the heat transfer oil to 50-60℃, it is stored in the heat transfer oil hot tank. (2) The high-temperature heat transfer oil in the heat transfer oil hot tank is transported to the CO2 evaporator of the compressed CO2 energy storage unit. The high-temperature heat transfer oil provides heat for the vaporization of liquid CO2, thereby causing it to vaporize. In the compressed CO2 energy storage unit, the compressed CO2 is expanded, compressed, and liquefied. After the high-temperature heat transfer oil completes heat exchange in the CO2 evaporator, it is cooled to 35°C to become low-temperature heat transfer oil. The low-temperature heat transfer oil is then transported to the heat transfer oil cold tank. (3) Repeat steps (1) and (2) to make the cycle of low-temperature heat transfer oil → gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in CO2 evaporator → low-temperature heat transfer oil → gas-liquid heat exchanger → high-temperature heat transfer oil → waste heat utilization in CO2 evaporator possible; at the same time, make the liquid CO2 evaporate, expand, compress, liquefy and re-evaporate in the compressed CO2 energy storage unit in a cycle to realize the continuous operation of compressed CO2 energy storage by utilizing the waste heat of flue gas; (4) When the temperature of the heat transfer oil in the heat transfer oil tank is lower than 48°C, open the valve of the flue gas bypass pipe to introduce the flue gas into the gas-liquid heat exchanger, and at the same time pump the heat transfer oil in the heat transfer oil tank into the gas-liquid heat exchanger to raise the temperature of the heat transfer oil to 50-60°C.