Reverse exhaust carbon dioxide recovery system for oil well

Abstract

The utility model discloses an oil well reverse exhaust carbon dioxide recovery system which comprises a gas-liquid separator, a dryer, a residual cold recoverer, a purifier, a product pump and a CO2 liquefying unit, the dryer is communicated with a feed gas outlet pipeline on the gas-liquid separator, the residual cold recoverer is communicated with a dry gas outlet pipeline on the dryer, and the CO2 liquefying unit is communicated with the product pump. The purifier is communicated with a non-condensable tail gas inlet pipeline on the residual cold recoverer, the residual cold recoverer is communicated with a purified gas inlet pipeline on the purifier, the product pump is communicated with a liquid CO2 outlet pipeline I on the purifier, and the CO2 liquefying unit is communicated with a purified gas outlet pipeline on the purifier. And the purifier is communicated with a liquid CO2 outlet pipeline II on the CO2 liquefying unit. According to the oil well reverse exhaust gas recycling device, after liquid CO2 is obtained through gas-liquid separation, drying, purification, liquefaction and other links, the liquid CO2 is injected into an oil well again to be fractured, recycling of CO2 is achieved, and the purchase and transportation cost of the carbon dioxide for oil well fracturing can be greatly reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of carbon dioxide recovery and reuse, and in particular relates to an oil well exhaust gas carbon dioxide recovery system. Background Art

[0002] Oil and gas well fracturing, also known as hydraulic fracturing, refers to the use of high-pressure, large-displacement pumps to inject a liquid with a certain viscosity and special properties (fracture fluid) into the oil and gas layer at a rate greater than the absorption capacity of the formation, causing cracks in the formation, thereby improving the flow environment of oil and gas underground and increasing the output of oil and gas wells.

[0003] Oil well back exhaust is an important part after oil and gas well fracturing operation, which involves the discharge of fluids (including gas, liquid, etc.) in the formation after fracturing. After carbon dioxide fracturing of oil wells, the components of oil well back exhaust mainly include natural gas (such as hydrocarbon gases such as methane) and carbon dioxide. In the prior art, oil well back exhaust is generally temporarily flared, resulting in a waste of energy resources. Summary of the invention

[0004] The utility model aims to provide a technical solution for an oil well reverse exhaust carbon dioxide recovery system in view of the deficiencies in the prior art. The oil well reverse exhaust is separated into liquid CO2 through multiple steps such as gas-liquid separation, drying, purification and liquefaction, and then re-injected into the oil well for fracturing, thereby realizing the recycling and utilization of CO2, which can greatly reduce the purchase and transportation costs of carbon dioxide used for oil well fracturing and save resources.

[0005] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0006] The oil well exhaust gas carbon dioxide recovery system comprises a gas-liquid separator, a dryer, a waste cooling recovery device, a purifier, a product pump and a CO2 liquefaction unit, the gas-liquid separator is connected with a raw gas inlet pipeline and a raw gas outlet pipeline, the dryer is connected with the raw gas outlet pipeline, the dryer is connected with a dry gas outlet pipeline, the waste cooling recovery device is connected with the dry gas outlet pipeline, the waste cooling recovery device is connected with a non-condensable tail gas inlet pipeline and a non-condensable tail gas outlet pipeline, the purifier is connected with the non-condensable tail gas inlet pipeline, the purifier is connected with a purified gas inlet pipeline, a purified gas outlet pipeline and a liquid CO2 outlet pipeline 1, the waste cooling recovery device is connected with the purified gas inlet pipeline, the product pump is connected with the liquid CO2 outlet pipeline 1, the CO2 liquefaction unit is connected with the purified gas outlet pipeline, the CO2 liquefaction unit is connected with a liquid CO2 outlet pipeline 2, and the purifier is connected with the liquid CO2 outlet pipeline 2.

[0007] The reverse exhaust gas from the oil well enters the gas-liquid separator through the raw gas inlet pipeline for gas-liquid separation. The separated gas enters the dryer from the raw gas outlet pipeline for drying. The dried gas enters the residual cooling recovery device through the dry gas outlet pipeline, and exchanges heat with the non-condensable tail gas entering the residual cooling recovery device for cooling. The gas after heat exchange and cooling enters the purifier through the purified gas inlet pipeline, and exchanges heat with the CO2 liquid entering the purifier for cooling again. The gas after heat exchange and cooling again enters the CO2 liquefaction unit through the purified gas outlet pipeline for liquefaction. The liquefied liquid CO2 enters the purifier through the liquid CO2 outlet pipeline 2 for heat exchange and purification. The product pump extracts the purified liquid CO2 from the liquid CO2 outlet pipeline 1, and the non-condensable tail gas generated after purification enters the residual cooling recovery device from the non-condensable tail gas inlet pipeline to recover the residual cooling. The oil well exhaust gas is separated into liquid CO2 through multiple steps such as gas-liquid separation, drying, purification and liquefaction, and then re-injected into the oil well for fracturing to achieve the recycling of CO2. This can greatly reduce the purchase and transportation costs of carbon dioxide for oil well fracturing and save resources. The CO2 liquefaction unit combined with the purifier in the recovery system can increase the concentration of the final liquid CO2 product.

[0008] Furthermore, a waste liquid discharge pipeline is arranged at the bottom of the gas-liquid separator, and a discharge regulating valve is arranged on the waste liquid discharge pipeline. The liquid separated in the gas-liquid separator can be regularly discharged from the waste liquid discharge pipeline through the discharge regulating valve, and the waste liquid discharge flow and speed can be accurately controlled by adjusting the opening of the discharge regulating valve.

[0009] Furthermore, a raw gas regulating valve is provided on the raw gas inlet pipeline, and the raw gas regulating valve decompresses the oil well exhaust gas entering the recovery system, so that the oil well exhaust gas is decompressed to 5.0Mpa, about 9°C, which meets the gas pressure requirement for entering the recovery system and is also more conducive to the smooth progress of subsequent process steps.

[0010] Furthermore, the CO2 liquefaction unit includes a CO2 liquefier, a refrigeration compressor, an air cooler and a refrigerant liquid storage tank which are circulated and connected in sequence. The CO2 liquefier is connected to a liquid CO2 outlet pipeline and a purified gas outlet pipeline. The overall structural design is ingenious and reasonable. As the core component of the CO2 liquefaction unit, the CO2 liquefier can effectively convert gaseous CO2 into liquid. The various module components in the CO2 liquefaction unit are relatively independent and connected through pipelines, which is convenient for subsequent maintenance.

[0011] Furthermore, it also includes a regenerative electric heater, which is connected to the non-condensable tail gas outlet pipeline, the regenerative tail gas outlet pipeline is connected to the regenerative electric heater, and the dryer is connected to the regenerative tail gas outlet pipeline; the non-condensable tail gas after the residual cooling is recovered by the residual cooling recovery device enters the regenerative electric heater from the non-condensable tail gas outlet pipeline for heating, and then enters the dryer from the regenerative tail gas outlet pipeline as regenerative tail gas. A regenerative electric heater is also provided in the whole recovery system, which can be started when the dryer needs to be regenerated through the regenerative electric heater. When the dryer is saturated with adsorbed water and needs to be regenerated, the switch valve on the tail gas emission main pipeline is closed. The non-condensable tail gas after recovery of residual cooling is used as the regeneration gas source of the dryer. It is heated to 180-220℃ in the regeneration electric heater, and then goes to the dryer that needs to be regenerated for reverse heating and regeneration. When the temperature of the regenerated tail gas coming out of the dryer reaches 100-130℃, it means that the regeneration heating of the dryer is over, the regeneration electric heater is turned off, and the regenerated dryer is blown cold. When the temperature of the regenerated tail gas drops back to 25-40℃, the cooling is completed, ensuring that the dryer returns to the optimal adsorption state and the system stability. Then open the switch valve on the exhaust gas main pipeline to ensure the normal emission process of the non-condensable tail gas.

[0012] Furthermore, the non-condensable tail gas outlet pipeline is connected to the tail gas emission main pipeline, and a switch valve is arranged on the tail gas emission main pipeline, through which the emission of the non-condensable tail gas can be flexibly controlled. When the non-condensable tail gas needs to be discharged normally, the switch valve can be opened, and when the dryer enters the regeneration operation process, the switch valve is closed, which is convenient for actual operation adjustment, and the non-condensable tail gas is discharged centrally through the tail gas emission main pipeline, which can facilitate the unified collection and treatment of the non-condensable tail gas, so as to transport the non-condensable tail gas to the gas recovery device at the wellhead of the oil well to recover the methane in the non-condensable tail gas, or directly use the non-condensable tail gas as fuel. The material is transported to the gas turbine that drives the refrigeration compressor in the CO2 liquefaction unit, so that the waste non-condensable tail gas can be recycled on-site, reducing the energy loss of the entire recovery system. The refrigeration compressor is driven by the gas turbine. The gas turbine has high energy efficiency, compact structure and small size, stable equipment operation, and improves the overall operation stability of the system. It also has good starting acceleration performance. In particular, the non-condensable tail gas generated in the recovery system is used as fuel to drive the gas turbine, which can reduce the overall energy consumption of the system. The gas turbine can even achieve zero-power cold start without relying on additional electricity, which increases the flexibility of system use.

[0013] Furthermore, a regenerated exhaust gas exhaust pipeline is connected to the dryer, and the regenerated exhaust gas exhaust pipeline is connected to the exhaust gas main pipeline. The switch valve is located at the front end of the connection node between the regenerated exhaust gas exhaust pipeline and the exhaust gas main pipeline. The design is reasonable. The regenerated exhaust gas exhaust pipeline is used to discharge the regenerated exhaust gas during the regeneration process of the dryer. The regenerated exhaust gas exhaust pipeline is connected to the exhaust gas main pipeline, so that the regenerated exhaust gas and non-condensable exhaust gas are discharged centrally through the exhaust gas main pipeline. The pipeline layout is more reasonable and compact, and it is also more conducive to the unified collection and treatment of the regenerated exhaust gas and non-condensable exhaust gas. The design position of the switch valve is limited, so that when the switch valve is closed, it will not affect the emission process of the regenerated exhaust gas.

[0014] Furthermore, a non-condensable exhaust gas regulating valve is provided on the non-condensable exhaust gas inlet pipeline, through which the non-condensable exhaust gas separated in the purifier can be depressurized, so that the non-condensable exhaust gas of 5.0 MPa and -20°C is depressurized to 0.05 MPa and -70°C, and then goes to the residual cold recovery device to recover the residual cold.

[0015] Furthermore, the dryer includes a dryer 1 and a dryer 2 arranged in parallel. The design is more ingenious. Two dryers 1 and 2 arranged in parallel are adopted. One of them can be in operation while the other can be in standby. When one of the dryers is in the regeneration process or under overhaul and maintenance, the other dryer can continue to operate to ensure the continuous operation of the entire recovery system. The number of operating dryers can also be adjusted according to the actual load conditions to achieve optimal utilization of energy.

[0016] The utility model has the following beneficial effects due to the adoption of the above technical solution:

[0017] In the utility model, the reverse exhaust gas of the oil well is separated through gas-liquid separation, drying, purification and liquefaction to obtain liquid CO2, which is then re-injected into the oil well for fracturing to realize the circulation and recovery of CO2, thereby greatly reducing the purchase and transportation costs of carbon dioxide for oil well fracturing and saving resources. At the same time, two parallel-connected dryers, one and the other, are adopted in the recovery system, and one of them can be opened and the other can be kept in reserve, so that when one of the dryers is in the regeneration process or under maintenance, the other dryer can continue to operate to ensure the continuous operation of the entire recovery system. The number of operating dryers can also be adjusted according to the actual load conditions to achieve optimal utilization of energy. Moreover, the methane-rich non-condensable tail gas discharged from the entire recovery system is not directly discharged, but is introduced into the gas recovery device at the wellhead of the oil well to recover methane, or is directly transported as fuel to the gas turbine in the CO2 liquefaction unit that drives the refrigeration compressor to operate, so that the discarded non-condensable tail gas can be recycled on the spot, further realizing the recycling of resources and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The utility model is further described below in conjunction with the accompanying drawings:

[0019] Figure 1 It is a process flow chart of the present invention when the non-condensable tail gas and the regenerated tail gas are transported to the fuel gas recovery device;

[0020] Figure 2 This is a process flow chart of the present invention when the non-condensable tail gas and the regenerated tail gas are transported to the gas turbine.

[0021] In the figure: 1-gas-liquid separator; 2-raw gas inlet pipeline; 3-raw gas inlet pipeline; 4-drying gas outlet pipeline; 5-residual cooling recovery device; 6-non-condensable tail gas inlet pipeline; 7-non-condensable tail gas outlet pipeline; 8-purifier; 9-purified gas inlet pipeline; 10-purified gas outlet pipeline; 11-liquid CO2 outlet pipeline 2; 12-product pump; 13-CO2 liquefaction unit; 14-liquid CO2 outlet pipeline 1 ; 15-waste liquid discharge pipeline; 16-CO2 liquefier; 17-refrigeration compressor; 18-air cooler; 19-refrigerant liquid storage tank; 20-regeneration electric heater; 21-regeneration tail gas outlet pipeline; 22-regeneration tail gas discharge pipeline; 23-dryer one; 24-dryer two; 25-tail gas discharge main pipeline; F1-raw gas regulating valve; F2-drain regulating valve; F3-non-condensable tail gas regulating valve; F4-switch valve. DETAILED DESCRIPTION

[0022] like Figure 1 and Figure 2 As shown, the utility model is an oil well reverse exhaust carbon dioxide recovery system, including a gas-liquid separator 1, a dryer, a residual cooling recovery device 5, a purifier 8, a product pump 12 and a CO2 liquefaction unit 13. The gas-liquid separator 1 is connected with a raw gas inlet pipeline 2 and a raw gas outlet pipeline 3. The raw gas inlet pipeline 2 is provided with a raw gas regulating valve F1. The raw gas regulating valve F1 decompresses the oil well reverse exhaust gas entering the recovery system, so that the oil well reverse exhaust gas is decompressed to 5.0Mpa, about 9°C, which meets the gas pressure requirements for entering the recovery system and is more conducive to the smooth progress of subsequent process steps. A waste liquid discharge pipeline 15 is provided at the bottom of the gas-liquid separator 1, and a liquid discharge regulating valve F2 is provided on the waste liquid discharge pipeline 15. The liquid separated in the gas-liquid separator 1 can be discharged from the waste liquid discharge pipeline 15 regularly through the liquid discharge regulating valve F2, and the waste liquid discharge flow rate and speed can be accurately controlled by adjusting the opening of the liquid discharge regulating valve F2.

[0023] The dryer is connected to the raw gas outlet pipeline 3, the dryer is connected to the dry gas outlet pipeline 4, the residual cooling recovery device 5 is connected to the dry gas outlet pipeline 4, the residual cooling recovery device 5 is connected to the non-condensable tail gas inlet pipeline 6 and the non-condensable tail gas outlet pipeline 7, the non-condensable tail gas inlet pipeline 6 is provided with a non-condensable tail gas regulating valve F3, and the non-condensable tail gas separated in the purifier 8 can be decompressed by the non-condensable tail gas regulating valve F3, so that the non-condensable tail gas of 5.0Mpa, -20°C is decompressed to 0.05Mpa, -70°C, and then goes to the residual cooling recovery device 5 to recover the residual cooling, the purifier 8 is connected to the non-condensable tail gas inlet pipeline 6, the purifier 8 is connected to the purified gas inlet pipeline 9, the purified gas outlet pipeline 10 and the liquid CO2 outlet pipeline 14, and the residual cooling recovery device 5 is connected to the purified gas inlet pipeline 9. The product pump 12 is connected to the liquid CO2 outlet pipeline 14. The non-condensable tail gas outlet pipeline 7 is connected to the tail gas emission main pipeline 25, and the tail gas emission main pipeline 25 is provided with a switch valve F4, through which the emission of the non-condensable tail gas can be flexibly controlled. When the non-condensable tail gas needs to be discharged normally, the switch valve F4 can be opened, and when the dryer enters the regeneration operation process, the switch valve F4 is closed, which is convenient for actual operation adjustment. The non-condensable tail gas is discharged centrally through the tail gas emission main pipeline 25, which can facilitate the unified collection and treatment of the non-condensable tail gas, so that the non-condensable tail gas can be transported to the gas recovery device at the wellhead of the oil well to recover the methane in the non-condensable tail gas, or the non-condensable tail gas can be directly used as a fuel for transmission. The waste non-condensable tail gas is sent to the gas turbine 26 in the CO2 liquefaction unit 13 for driving the refrigeration compressor 17, so that the waste non-condensable tail gas can be recycled on site, reducing the energy loss of the entire recovery system. The refrigeration compressor 17 is driven by the gas turbine 26. The gas turbine 26 has a high energy efficiency ratio, a compact structure, a small size, and a stable equipment operation, which improves the overall operation stability of the system and has good starting acceleration performance. In particular, the non-condensable tail gas generated in the recovery system is used as fuel to drive the gas turbine 26, which can reduce the overall energy consumption of the system. What's more, the gas turbine 26 can achieve zero-power cold start without relying on additional electricity, thereby increasing the flexibility of system use.

[0024] The CO2 liquefaction unit 13 is connected to the purified gas outlet pipeline 10, and the CO2 liquefaction unit 13 is connected to the liquid CO2 outlet pipeline 2 11, and the purifier 8 is connected to the liquid CO2 outlet pipeline 2 11. The CO2 liquefaction unit 13 includes a CO2 liquefier 16, a refrigeration compressor 17, an air cooler 18 and a refrigerant liquid storage tank 19 that are cyclically connected in sequence. The CO2 liquefier 16 is connected to the liquid CO2 outlet pipeline 2 11 and the purified gas outlet pipeline 10. The overall structural design is ingenious and reasonable. The CO2 liquefier 16, as the core component of the CO2 liquefaction unit 13, can effectively convert gaseous CO2 into liquid. The various module components in the CO2 liquefaction unit 13 are relatively independent and connected through pipelines, which is convenient for subsequent maintenance.

[0025] The reverse exhaust gas from the oil well enters the gas-liquid separator 1 through the raw gas inlet pipeline 2 for gas-liquid separation. The separated gas enters the dryer from the raw gas outlet pipeline 3 for drying. The dried gas enters the residual cooling recovery device 5 through the dry gas outlet pipeline 4, and exchanges heat with the non-condensable tail gas entering the residual cooling recovery device 5 for cooling. The gas after heat exchange and cooling enters the purifier 8 through the purified gas inlet pipeline 9, and exchanges heat with the CO2 liquid entering the purifier 8 for cooling again. The gas after heat exchange and cooling again enters the CO2 liquefaction unit 13 through the purified gas outlet pipeline 10 for liquefaction. The liquefied liquid CO2 enters the purifier 8 through the liquid CO2 outlet pipeline 2 11 for heat exchange and purification. The product pump 12 extracts the purified liquid CO2 from the liquid CO2 outlet pipeline 14. The non-condensable tail gas generated after purification enters the residual cooling recovery device 5 from the non-condensable tail gas inlet pipeline 6 to recover the residual cooling. The oil well exhaust gas is separated into liquid CO2 through multiple steps such as gas-liquid separation, drying, purification and liquefaction, and then re-injected into the oil well for fracturing to achieve the recycling of CO2. This can greatly reduce the purchase and transportation costs of carbon dioxide for oil well fracturing and save resources. The CO2 liquefaction unit 13 combined with the purifier 8 in the recovery system can increase the concentration of the final liquid CO2 product.

[0026] The recovery system also includes a regenerative electric heater 20, which is connected to the non-condensable tail gas outlet pipeline 7, and a regenerative tail gas outlet pipeline 21 is connected to the regenerative electric heater 20, and the dryer is connected to the regenerative tail gas outlet pipeline 21; the non-condensable tail gas after the residual cooling is recovered by the residual cooling recovery device 5 enters the regenerative electric heater 20 from the non-condensable tail gas outlet pipeline 7 and is heated, and then enters the dryer from the regenerative tail gas outlet pipeline 21 as the regenerative tail gas. The whole recovery system is also provided with a regenerative electric heater 20, which can be started when the dryer needs to be regenerated through the regenerative electric heater 20, and the tail gas outlet pipeline 21 is closed when the dryer needs to be regenerated when the moisture adsorption of the dryer is saturated. The switch valve F4 on the main pipeline 25 is opened, and the non-condensable tail gas after residual cooling is recovered as the regeneration gas source of the dryer. It is heated to 200°C in the regeneration electric heater 20, and then goes to the dryer that needs to be regenerated for reverse heating and regeneration. When the temperature of the regenerated tail gas coming out of the dryer reaches 120°C, it means that the regeneration heating of the dryer is completed, and the regeneration electric heater 20 is closed to cool the regenerated dryer. When the temperature of the regenerated tail gas drops back to 30°C, the cooling is completed, ensuring that the dryer returns to the optimal adsorption state and the system stability. Then the switch valve F4 on the tail gas emission main pipeline 25 is opened to ensure the normal emission process of the non-condensable tail gas.

[0027] The dryer is connected with a regeneration tail gas exhaust pipeline 22, which is connected to the tail gas emission main pipeline 25. The switch valve F4 is located at the front end of the connection node between the regeneration tail gas exhaust pipeline 22 and the tail gas emission main pipeline 25. The design is reasonable. The regeneration tail gas exhaust pipeline 22 is used to discharge the regeneration tail gas during the regeneration process of the dryer. The regeneration tail gas exhaust pipeline 22 is connected to the tail gas emission main pipeline 25, so that the regeneration tail gas and the non-condensable tail gas are discharged centrally through the tail gas emission main pipeline 25. The pipeline layout is more reasonable and compact, and it is also more conducive to the unified collection and treatment of the regeneration tail gas and the non-condensable tail gas. In addition, the design position of the switch valve F4 is limited, so that when the switch valve F4 is closed, it will not affect the discharge process of the regeneration tail gas. The dryer includes a dryer 1 23 and a dryer 24 arranged in parallel. The design is more ingenious. Two dryers 1 23 and two dryers 24 are arranged in parallel. One of them can be in operation while the other can be in standby mode. When one of the dryers is in the regeneration process or under repair and maintenance, the other dryer can continue to operate to ensure the continuous operation of the entire recovery system. The number of operating dryers can also be adjusted according to the actual load conditions to achieve optimal utilization of energy.

[0028] In the utility model, the oil well reverse exhaust gas after the oil well carbon dioxide fracturing is mainly composed of carbon dioxide and methane, wherein the CO2 concentration is in the range of 35% to 95%. The oil well reverse exhaust gas is separated by gas-liquid separation, drying, purification and liquefaction to obtain liquid CO2, which is then re-injected into the oil well for fracturing to achieve the recycling and reuse of CO2, thereby greatly reducing the purchase and transportation costs of carbon dioxide for oil well fracturing and saving resources. At the same time, two parallel-connected dryers 23 and 24 are used in the recovery system, and the two can be one in operation and the other in standby, so that when one of them is During the regeneration process or overhaul and maintenance of the dryer, the other dryer can continue to operate to ensure the continuous operation of the entire recovery system. The number of operating dryers can also be adjusted according to the actual load conditions to achieve optimal utilization of energy. Moreover, the methane-rich non-condensable tail gas discharged from the entire recovery system is not directly discharged, but is introduced into the gas recovery device at the wellhead of the oil well to recover methane, or is directly transported as fuel to the gas turbine 26 in the CO2 liquefaction unit 13 that drives the refrigeration compressor 17 to operate, so that the discarded non-condensable tail gas can be reused as a resource on site, further realizing the reuse of resources and reducing production costs.

[0029] The specific working process of the utility model is as follows:

[0030] The exhaust gas from the wellhead is decompressed to 5.0Mpa by the raw gas regulating valve F1, and then goes to the gas-liquid separator 1 to separate the liquid impurities at about 9°C, and then goes to the dryer for drying and dehydration to prevent ice blockage during subsequent liquefaction separation, and then goes to the residual cooling recovery device 5 to recover the non-condensable tail gas. The residual cooling itself is cooled to about 8°C, and then goes to the purifier 8 as a heat source for reboiling to increase the concentration of the recovered liquid CO2, and then is cooled to about 5°C again, and then goes to the CO2 liquefier 16 in the CO2 liquefaction unit 13 for liquefaction at -25°C. After liquefaction, the non-condensable tail gas is separated from the purifier 8. The liquid CO2 purified by reboiler in the purifier 8 is sent to the oil well for fracturing by the product pump 12 as fracturing CO2. The non-condensable tail gas of 5.0Mpa and -20°C separated from the purifier 8 is decompressed to 0.05Mpa and -70°C by the non-condensable tail gas regulating valve F3 and then goes to the residual cooling recovery device 5 to recover the residual cooling. Under normal circumstances, the non-condensable tail gas rich in methane of 0.05Mpa and 3°C coming out of the residual cooling recovery device 5 is discharged through the non-condensable tail gas outlet pipeline 7 and the tail gas exhaust main pipeline 25. The gas recovery device sent to the wellhead of the oil well recovers the methane in the non-condensable tail gas, or directly transports it as fuel to the gas turbine 26 driving the refrigeration compressor 17, so as to realize the reuse of energy and reduce energy consumption loss. When the dryer adsorbs water saturated and needs to be regenerated, the switch valve F4 is closed, and the non-condensable tail gas after the residual cooling is recovered is used as the regeneration gas source of the dryer, and is heated to 180-220°C by the regeneration electric heater 20, and then goes to the dryer that needs to be regenerated for reverse heating and regeneration. When the temperature of the regenerated tail gas from the dryer reaches 100- When the temperature of the dryer reaches 130℃, the regeneration heating of the dryer is finished, the regeneration electric heater 20 is turned off, and the regenerated dryer is cooled. When the temperature of the regenerated exhaust gas drops back to 25-40℃, the cooling is completed, the switch valve F4 is opened, and the non-condensable exhaust gas emission is switched to the normal process. The dryer regeneration is completed, and the non-condensable exhaust gas and the dryer regeneration exhaust gas are discharged through the exhaust gas emission main pipeline 25 and sent to the gas recovery device at the wellhead of the oil well to recover the methane in the non-condensable exhaust gas, or directly transported as fuel to the gas turbine 26 that drives the refrigeration compressor 17 to reduce energy consumption loss.

[0031] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent replacements or modifications made based on the present invention to achieve basically the same technical effects are all included in the protection scope of the present invention.

Claims

1. Oil well exhaust carbon dioxide recovery system, characterized by: include: A gas-liquid separator, the gas-liquid separator is connected to a raw gas inlet pipeline and a raw gas outlet pipeline; a dryer, the dryer is connected to the raw gas outlet pipeline, and the dryer is connected to a dry gas outlet pipeline; A waste cooling recovery device, the waste cooling recovery device is in communication with the dry gas outlet pipeline, and the waste cooling recovery device is connected with a non-condensable tail gas inlet pipeline and a non-condensable tail gas outlet pipeline; A purifier, the purifier is connected to the non-condensable tail gas inlet pipeline, the purifier is connected to a purified gas inlet pipeline, a purified gas outlet pipeline and a liquid CO2 outlet pipeline, and the residual cooling recovery device is connected to the purified gas inlet pipeline; A product pump, the product pump being in communication with the liquid CO2 outlet pipeline; A CO2 liquefaction unit, the CO2 liquefaction unit is connected to the purified gas outlet pipeline, a second liquid CO2 outlet pipeline is connected to the CO2 liquefaction unit, and the purifier is connected to the second liquid CO2 outlet pipeline; The reverse exhaust gas from the oil well enters the gas-liquid separator through the raw gas inlet pipeline for gas-liquid separation, the separated gas enters the dryer from the raw gas outlet pipeline for drying, the dried gas enters the residual cooling recovery device through the dry gas outlet pipeline, and exchanges heat with the non-condensable tail gas entering the residual cooling recovery device for cooling, the gas after heat exchange and cooling enters the purifier through the purified gas inlet pipeline, and exchanges heat with the CO2 liquid entering the purifier for cooling again, the gas after heat exchange and cooling again enters the CO2 liquefaction unit through the purified gas outlet pipeline for liquefaction, the liquefied liquid CO2 enters the purifier through the liquid CO2 outlet pipeline 2 for heat exchange and purification, the product pump extracts the purified liquid CO2 from the liquid CO2 outlet pipeline 1, and the non-condensable tail gas generated after purification enters the residual cooling recovery device from the non-condensable tail gas inlet pipeline to recover residual cooling.

2. The oil well exhaust carbon dioxide recovery system according to claim 1, characterized in that: A waste liquid discharge pipeline is arranged at the bottom of the gas-liquid separator, and a discharge regulating valve is arranged on the waste liquid discharge pipeline.

3. The oil well exhaust carbon dioxide recovery system according to claim 1, characterized in that: The raw gas inlet pipeline is provided with a raw gas regulating valve.

4. The oil well exhaust carbon dioxide recovery system according to claim 1, characterized in that: The CO2 liquefaction unit comprises a CO2 liquefier, a refrigeration compressor, an air cooler and a refrigerant liquid storage tank which are cyclically connected in sequence. The CO2 liquefier is connected to the second liquid CO2 outlet pipeline and the purified gas outlet pipeline.

5. The oil well exhaust carbon dioxide recovery system according to claim 1, characterized in that: It also includes a regenerative electric heater, the regenerative electric heater is connected to the non-condensable tail gas outlet pipeline, the regenerative tail gas outlet pipeline is connected to the regenerative electric heater, and the dryer is connected to the regenerative tail gas outlet pipeline; The non-condensable tail gas after the residual cooling is recovered by the residual cooling recovery device enters the regeneration electric heater from the non-condensable tail gas outlet pipeline for heating, and then enters the dryer from the regeneration tail gas outlet pipeline as the regeneration tail gas.

6. The oil well exhaust carbon dioxide recovery system according to claim 1, characterized in that: The non-condensable tail gas outlet pipeline is connected to the tail gas emission main pipeline, a switch valve is arranged on the tail gas emission main pipeline, and the tail gas emission main pipeline is connected to the gas recovery device at the wellhead of the oil well or the gas turbine driving the refrigeration compressor.

7. The oil well exhaust carbon dioxide recovery system according to claim 6, characterized in that: The dryer is connected with a regeneration exhaust gas exhaust pipeline, which is communicated with the exhaust gas exhaust main pipeline, and the switch valve is located at the front end of the connection node between the regeneration exhaust gas exhaust pipeline and the exhaust gas exhaust main pipeline.

8. The oil well exhaust carbon dioxide recovery system according to claim 1, characterized in that: The non-condensable tail gas inlet pipeline is provided with a non-condensable tail gas regulating valve.

9. The oil well exhaust carbon dioxide recovery system according to claim 1, characterized in that: The dryer comprises a first dryer and a second dryer which are arranged in parallel.

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