Separation unit used for carbon dioxide displacement in coalbed methane production

Abstract

A separation device for producing coalbed methane using carbon dioxide displacement, relating to the technical field of coalbed methane production equipment, includes a first separation section and a second separation section. The first separation section includes a first cylinder, a second cylinder, a third cylinder, a circulating pump, and a flow direction adjustment valve. The flow direction adjustment valve has a first operating state and a second operating state. In the first operating state, the circulating pump draws out dehydrating agent from the first cylinder and pumps the drawn-out dehydrating agent into the second cylinder. In the second operating state, the circulating pump draws out dehydrating agent from the second cylinder and pumps the drawn-out dehydrating agent into the first cylinder. The second separation section includes a mixer and a separator. The third cylinder is connected to the mixer via a connecting pipeline. The coalbed methane in the third cylinder flows sequentially through the mixer and separator via the connecting pipeline, mixing with ethylene glycol in the mixer and separating from ethylene glycol in the separator. This invention separates and removes moisture from coalbed methane through the first and second separation sections.

Description

Technical Field

[0001] This invention relates to the field of coalbed methane production equipment technology, and more specifically to a separation device for producing coalbed methane by carbon dioxide displacement. Background Technology

[0002] Carbon dioxide displacement process for coalbed methane production ( Its principle is to use stronger adsorption force. This process, which "displaces" methane from the micropores of coal, is the optimal solution for the efficient development of deep coalbed methane and is also the most mature and scalable technology direction for CCUS in the coal sector.

[0003] In the practice of producing coalbed methane using carbon dioxide displacement, the applicant discovered that after initial collection, the coalbed methane carries moisture and carbon dioxide that has not been adsorbed by the coal seam. The mixture of moisture and carbon dioxide is acidic, and the reaction formula is as follows:

[0004] The acidic components in coalbed methane accelerate the corrosion rate of the inner wall of gas pipelines, reduce the service life of gas pipelines, and increase the probability of safety accidents. Summary of the Invention

[0005] The present invention addresses the aforementioned technical problems in the prior art by providing a separation device for producing coalbed methane using carbon dioxide displacement, which can effectively remove moisture from the coalbed methane.

[0006] To achieve the above technical objectives, embodiments of the present invention provide a separation device for producing coalbed methane using carbon dioxide displacement, comprising: a first separation section and a second separation section. The first separation section includes a first cylinder, a second cylinder, a third cylinder, a circulating pump, and a flow direction adjustment valve. A gas inlet is connected to the top of the first cylinder via a first inflow one-way valve to unidirectionally supply coalbed methane to be processed into the first cylinder. A gas inlet is connected to the top of the second cylinder via a second inflow one-way valve to unidirectionally supply coalbed methane to be processed into the second cylinder. The top of the first cylinder is connected to the bottom of the third cylinder via a first outflow one-way valve to unidirectionally supply coalbed methane into the third cylinder. The top of the second cylinder is connected to the bottom of the third cylinder via a second outflow one-way valve to unidirectionally supply coalbed methane into the third cylinder. One end of the circulating pump is connected to the bottom of the first cylinder via the flow direction adjustment valve, and the other end of the circulating pump is connected to the flow direction adjustment valve via the flow direction adjustment valve. The regulating valve is connected to the bottom of the second cylinder; the first cylinder, the second cylinder, and the third cylinder are equipped with a dehydrating agent; the flow regulating valve has a first working state and a second working state. In the first working state, the circulating pump draws out the dehydrating agent from the first cylinder and pumps the drawn-out dehydrating agent into the second cylinder; the first cylinder draws in coalbed methane, and the second cylinder discharges the coalbed methane into the third cylinder; in the second working state, the circulating pump draws out the dehydrating agent from the second cylinder and pumps the drawn-out dehydrating agent into the first cylinder; the second cylinder draws in coalbed methane, and the first cylinder discharges the coalbed methane into the third cylinder; the second separation section includes a mixer and a separator. The third cylinder is connected to the mixer via a connecting pipe. The coalbed methane in the third cylinder flows sequentially through the mixer and the separator via the connecting pipe, mixes with ethylene glycol in the mixer, and separates from ethylene glycol in the separator.

[0007] In one possible implementation, the flow direction regulating valve is a two-position four-way solenoid directional valve.

[0008] In one possible implementation, the system further includes a controller, a first liquid level sensor, and a second liquid level sensor; the first liquid level sensor is mounted on the top of the first cylinder and is used to detect the liquid level of the dehydrating agent in the first cylinder; the second liquid level sensor is mounted on the top of the second cylinder and is used to detect the liquid level of the dehydrating agent in the second cylinder; the controller is signal-connected to the first liquid level sensor, the second liquid level sensor, and the flow direction adjustment valve, respectively; the liquid level of the dehydrating agent in the first cylinder has a first high level and a first low level; the liquid level of the dehydrating agent in the second cylinder has a second high level and a second low level; the controller is configured to, in the... In the first operating state, when the liquid level of the dehydrating agent in the first cylinder detected by the first liquid level sensor reaches the first low level and the liquid level of the dehydrating agent in the second cylinder detected by the second liquid level sensor reaches the second level, the flow direction adjustment valve is controlled to switch from the first operating state to the second operating state; in the second operating state, when the liquid level of the dehydrating agent in the second cylinder detected by the second liquid level sensor reaches the second low level and the liquid level of the dehydrating agent in the first cylinder detected by the first liquid level sensor reaches the first high level, the flow direction adjustment valve is controlled to switch from the second operating state to the first operating state.

[0009] In one possible implementation, a first delivery pump is further included, one end of which is connected to the bottom of the first cylinder and the other end of which is connected to the bottom of the third cylinder; the controller is signal-connected to the first delivery pump; the controller is configured to, in the first operating state, if the liquid level in the second cylinder reaches the second high level and the liquid level in the first cylinder has not dropped to the first low level, it is determined that there is too much dehydrating agent in circulation, and the controller starts the first delivery pump to deliver the dehydrating agent in the first cylinder to the third cylinder; if the liquid level in the first cylinder drops to the first low level and the liquid level in the second cylinder has not reached the second high level, it is determined that there is too little dehydrating agent in circulation, and the controller starts the first delivery pump to deliver the dehydrating agent in the third cylinder to the first cylinder.

[0010] In one possible implementation, a second delivery pump and a third liquid level sensor are further included. The third liquid level sensor is mounted on the third cylinder and is used to detect the liquid level height inside the third cylinder. The controller is signal-connected to both the second delivery pump and the third liquid level sensor. The second delivery pump is connected to the bottom of the third cylinder and is used to extract or deliver medium into the third cylinder. The controller is configured to, when the liquid level height detected by the third liquid level sensor in the third cylinder is lower than a first preset height, control the second delivery pump to deliver medium into the third cylinder; and when the liquid level height in the third cylinder is higher than the second preset height, control the second delivery pump to extract medium from the third cylinder, wherein the second preset height is higher than the first preset height.

[0011] In one possible implementation, the mixer has a first inlet, a second inlet, and a mixing outlet; the first inlet is connected to the upper part of the third cylinder via a connecting pipe, for allowing the pressurized coalbed methane from the first separation section to flow into the first inlet through the connecting pipe; the second inlet is used to draw in ethylene glycol; the ethylene glycol mixes with the coalbed methane and then flows out through the mixing outlet.

[0012] In one possible implementation, the mixer has a mixing tube that, from top to bottom, is provided with a first contraction section, a first throat section, a first diffusion section, a connecting tube, a second contraction section, a second throat section, and a second diffusion section; the first throat section is connected to a storage container through a second inlet; the upper port cross-sectional dimension of the first contraction section is larger than its lower port cross-sectional dimension, gradually decreasing from top to bottom; and the upper port cross-sectional dimension of the first diffusion section is smaller than its lower port cross-sectional dimension, gradually increasing from top to bottom; the second inlet is connected to the first throat section and is used to create a negative pressure at the second inlet to draw in ethylene glycol.

[0013] In one possible implementation, the upper port cross-sectional dimension of the second contraction section is larger than that of its lower port cross-sectional dimension, gradually decreasing from top to bottom; and the upper port dimension of the second diffusion section is smaller than that of its lower port cross-sectional dimension, gradually increasing from top to bottom; a central tube coaxial with the second contraction section is provided inside the second contraction section, forming an annular space between the central tube and the second contraction section, and the lower end opening of the central tube is reduced to form a constricted portion, which is located inside the second throat section.

[0014] In one possible implementation, the separator includes a housing section that is cylindrical in shape, with a tangential inlet on the outer contour of the housing section through which the mixed fluid flows in; a gas outlet at the top of the housing section through which coalbed methane is discharged; and a liquid outlet at the bottom of the housing section through which ethylene glycol is discharged.

[0015] In one possible implementation, a filter section is provided inside the housing portion, the filter section being located above the tangential inlet; a funnel section is also provided inside the housing portion, the ethylene glycol flowing in from the tangential inlet forms a swirling flow on the inner wall of the housing portion and collects inside the funnel section, flowing out from the lower port of the funnel section to the liquid outlet under its own weight.

[0016] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages: The separation device for producing coalbed methane using carbon dioxide displacement of the present invention includes a first separation section and a second separation section; the first separation section is used to draw in coalbed methane to be treated from the gas inlet, perform preliminary dehumidification and pressurization, and then transport the coalbed methane to the second separation section. In the second separation section, after the coalbed methane is mixed with ethylene glycol, the ethylene glycol adsorbs the water vapor in the coalbed methane, and then the gas and ethylene glycol are separated, thereby achieving the drying and dehumidification of the coalbed methane. Attached Figure Description

[0017] Figure 1 This is a system schematic diagram of a separation device for producing coalbed methane by carbon dioxide displacement, according to an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the mixer in a separation device for producing coalbed methane using carbon dioxide displacement, according to an embodiment of the present invention.

[0019] Figure 3 This is a cross-sectional view of a mixer in a separation device for producing coalbed methane using carbon dioxide displacement, according to an embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram of the separator in a separation device for producing coalbed methane using carbon dioxide displacement, according to an embodiment of the present invention.

[0021] Figure 5 This is a cross-sectional view of a separator in a separation device for producing coalbed methane using carbon dioxide displacement, according to an embodiment of the present invention.

[0022] Figure 6 This is a schematic diagram of a separation device for producing coalbed methane using carbon dioxide displacement, according to an embodiment of the present invention, applied to coalbed methane extraction.

[0023] Explanation of reference numerals in the attached figures 100. First separation section; 200. Second separation section; 1. First cylinder block; 2. Second cylinder block; 3. Third cylinder block; 4. Circulating pump; 5. Flow direction regulating valve; 6. Controller; 7. First delivery pump; 8. Second delivery pump; 9. First inflow check valve; 10. Second inflow check valve; 11. First outflow check valve; 12. Second outflow check valve; 13. First liquid level sensor; 14. Second liquid level sensor; 15. Third liquid level sensor; 16. Mixer; 160. Mixing tube; 161. First flow inlet; 162. Second flow inlet; 163. Mixing outlet; 164. First contraction section; 165. First throat section; 166. First diffuser section; 167. Connecting tube; 168. Second contraction section; 169. Second throat section; 1610. Second diffuser section; 1611. Central tube; 1612. Narrowing section; 1613. Annular space; 17. Separator; 170. Shell section; 171. Tangential inlet; 172. Liquid outlet; 173. Filter section; 174. Funnel section; 18. Ethylene glycol regenerator; 19. Storage container; 20. Gas inlet; 21. Gas outlet; 22. Connecting pipeline; 23. Injection well; 24. Mining well; 25. Coal seam. Detailed Implementation

[0024] Other objects and advantages of the present invention will become clear by explaining the preferred embodiments of the present application below.

[0025] Figure 1 This is a system schematic diagram of a separation device for producing coalbed methane by carbon dioxide displacement, according to an embodiment of the present invention.

[0026] like Figure 1 As shown, the separation device for producing coalbed methane using carbon dioxide displacement according to the present invention (hereinafter referred to as the separation device) includes a first separation section 100 and a second separation section 200. The first separation section 100 is used to draw in coalbed methane to be treated from the gas inlet 20, perform preliminary dehumidification and pressurization, and then transport the coalbed methane to the second separation section 200. In the second separation section 200, after the coalbed methane is mixed with ethylene glycol, the ethylene glycol adsorbs the water vapor in the coalbed methane, and then the gas and ethylene glycol are separated, thus achieving the drying and dehumidification of the coalbed methane.

[0027] Specifically, the first separation section 100 includes a first cylinder 1, a second cylinder 2, a third cylinder 3, a circulation pump 4, a flow direction adjustment valve 5, and a controller 6.

[0028] Gas inlet 20 is connected to the top of the first cylinder 1 through the first inflow check valve 9 to unidirectionally supply coalbed methane to be processed to the first cylinder 1; gas inlet 20 is connected to the top of the second cylinder 2 through the second inflow check valve 10 to unidirectionally supply coalbed methane to be processed to the second cylinder 2.

[0029] The top of the first cylinder 1 is connected to the bottom of the third cylinder 3 through the first outflow one-way valve 11, which is used to unidirectionally transport coalbed methane into the third cylinder 3; the top of the second cylinder 2 is connected to the bottom of the third cylinder 3 through the second outflow one-way valve 12, which is used to unidirectionally transport coalbed methane into the third cylinder 3.

[0030] A first liquid level sensor 13 is installed on the top of the first cylinder 1 to detect the liquid level height inside the first cylinder 1; a second liquid level sensor 14 is installed on the top of the second cylinder 2 to detect the liquid level height inside the second cylinder 2; and a third liquid level sensor 15 is installed on the top of the third cylinder 3 to detect the liquid level height inside the third cylinder 3.

[0031] One end of the circulating pump 4 is connected to the bottom of the first cylinder 1 via a flow direction adjustment valve 5, and the other end of the circulating pump 4 is connected to the bottom of the second cylinder 2 via the same valve. The flow direction adjustment valve 5 can be, for example, a two-position four-way solenoid directional valve.

[0032] The flow adjustment valve 5 has a first working state and a second working state. In the first working state, the circulation pump 4 draws out the medium from the first cylinder 1 and pumps the drawn medium into the second cylinder 2. In the second working state, the circulation pump 4 draws out the medium from the second cylinder 2 and pumps the drawn medium into the first cylinder 1.

[0033] To achieve the above control process, the controller 6 is connected to the first liquid level sensor 13, the second liquid level sensor 14 and the flow direction adjustment valve 5 respectively.

[0034] The medium liquid level in the first cylinder 1 has a preset first high level and a first low level; the medium liquid level in the second cylinder 2 has a preset second high level and a second low level.

[0035] In the first operating state, the circulating pump 4 draws media from the first cylinder 1 and pumps it into the second cylinder 2. The liquid level in the first cylinder 1, detected by the first liquid level sensor 13, gradually decreases, while the liquid level in the second cylinder 2, detected by the second liquid level sensor 14, gradually increases. When the liquid level detected by the first liquid level sensor 13 reaches the first low level and the liquid level detected by the second liquid level sensor 14 reaches the second high level, the controller 6 controls the valve core of the flow direction adjustment valve 5 to switch to the second operating state. In the second operating state, the circulating pump 4 draws media from the second cylinder 2 and pumps it into the first cylinder 1. The liquid level height detected by the first liquid level sensor 13 gradually increases, while the liquid level height detected by the second liquid level sensor 14 gradually decreases. When the liquid level detected by the first liquid level sensor 13 reaches the first high level and the liquid level detected by the second liquid level sensor 14 is at the second low level, the controller 6 controls the valve core of the flow direction adjustment valve 5 to switch to the first operating state, and this cycle repeats continuously.

[0036] In the first working state, the liquid level in the first cylinder 1 gradually decreases, creating a negative pressure in the first cylinder 1. This negative pressure causes the coalbed methane to flow from the gas inlet 20 through the first inflow check valve 9 into the first cylinder 1. Meanwhile, the liquid level in the second cylinder 2 gradually increases, and the coalbed methane in the upper part of the inner cavity of the second cylinder 2 flows out through the second outflow check valve 12 into the third cylinder 3.

[0037] In the second working state, the liquid level in the second cylinder 2 gradually decreases, creating a negative pressure inside the second cylinder 2. This negative pressure causes the coalbed methane to flow from the gas inlet 20 through the second inflow check valve 10 into the second cylinder 2, while the liquid level in the first cylinder 1 gradually increases. The coalbed methane in the upper part of the inner cavity of the first cylinder 1 flows out through the first outflow check valve 11 into the third cylinder 3.

[0038] In some embodiments, a medium is injected into the first cylinder 1, the second cylinder 2, and the third cylinder 3. This medium can be, for example, a dehydrating agent, and more specifically, ethylene glycol or triethylene glycol. Consequently, when the coalbed methane gas flows through the first cylinder 1, the second cylinder 2, and the third cylinder 3, it can come into contact with the dehydrating agent and lose some of its water vapor.

[0039] However, the dehydrating agent's absorption of moisture from the coalbed methane will cause the liquid level in each container to rise, affecting the normal operation of the equipment. To solve the above technical problem, the present invention further includes a first delivery pump 7 and a second delivery pump 8. One end of the first delivery pump 7 is connected to the bottom of the first cylinder 1, and the other end is connected to the bottom of the third cylinder 3.

[0040] In the first operating state, the liquid level in the first cylinder 1 gradually decreases. When the liquid level in the second cylinder 2 reaches the second high level, the liquid level in the first cylinder 1 fails to drop to the first low level, resulting in an excess of medium in both cylinders 1 and 2. The controller 6 controls the first delivery pump 7 to operate, delivering the medium from the first cylinder 1 to the third cylinder 3. When the liquid level detected by the first liquid level sensor 13 reaches the first low level, the first delivery pump 7 stops operating.

[0041] Additionally, in some embodiments, when the liquid level in the first cylinder 1 and the second cylinder 2 is low due to evaporation or other reasons, the controller 6 controls the first transfer pump 7 to operate in reverse, drawing liquid from the third cylinder 3 and pumping it into the first cylinder 1. When the liquid level detected by the first liquid level sensor 13 reaches the first low level, but the liquid level in the second cylinder 2 has not yet reached the second high level, the controller 6 controls the first transfer pump 7 to operate in reverse, drawing liquid from the third cylinder 3 and pumping it into the first cylinder 1. When the liquid level detected by the second liquid level sensor 14 reaches the second high level, the first transfer pump 7 stops operating.

[0042] Through the above process, the present invention can maintain the liquid volume in the first cylinder 1 and the second cylinder 2 at an optimal level.

[0043] Furthermore, in order to control the liquid level in the third cylinder 3 to a preset height, the present invention also includes a second delivery pump 8, and the controller 6 is signal-connected to the second delivery pump 8. The second delivery pump 8 is connected to the bottom of the third cylinder 3 and is used to extract or deliver media into the third cylinder 3.

[0044] Specifically, when the liquid level height of the third cylinder 3 detected by the third liquid level sensor 15 is lower than the first preset height, the controller 6 controls the second delivery pump 8 to deliver the medium into the third cylinder 3; when the liquid level height in the third cylinder 3 is higher than the second preset height, the controller 6 controls the second delivery pump 8 to extract the medium from the third cylinder 3, and the second preset height is higher than the first preset height.

[0045] Figure 2 This is a schematic diagram of the structure of the mixer 16 in a separation device for producing coalbed methane by carbon dioxide displacement according to an embodiment of the present invention. Figure 3 This is a cross-sectional view of a mixer 16 in a separation device for producing coalbed methane by carbon dioxide displacement, according to an embodiment of the present invention.

[0046] like Figures 1-3 As shown, the second separation section 200 includes a mixer 16, a separator 17, an ethylene glycol regenerator 18, and a storage container 19. The pressurized coalbed methane from the first separation section 100 enters the mixer 16, where it mixes with ethylene glycol and flows into the separator 17. The separator 17 separates the coalbed methane from the liquid; the separated coalbed methane is discharged from the gas outlet 21; the separated ethylene glycol enters the ethylene glycol regenerator to remove adsorbed moisture and flows to the storage container 19 for recycling by the mixer 16.

[0047] Specifically, the mixer 16 has a first inlet 161, a second inlet 162, and a mixing outlet 163. The first inlet 161 is connected to the upper part of the third cylinder 3 via a connecting pipe 22, and the coalbed methane pressurized in the first separation section 100 flows into the first inlet 161 through the connecting pipe 22. The second inlet 162 is used to draw in ethylene glycol. After the ethylene glycol mixes with the coalbed methane, it flows out through the mixing outlet 163.

[0048] The mixer 16 has a mixing tube 160, which, from top to bottom, is provided with a first contraction section 164, a first throat section 165, a first diffusion section 166, a connecting tube 167, a second contraction section 168, a second throat section 169, and a second diffusion section 1610. The first throat section 165 is connected to the storage container 19 through a second inlet 162.

[0049] The upper port cross-sectional dimension of the first contraction section 164 is larger than its lower port cross-sectional dimension, gradually decreasing from top to bottom; and the upper port cross-sectional dimension of the first diffuser section 166 is smaller than its lower port cross-sectional dimension, gradually increasing from top to bottom. The second inlet 162 is connected to the first throat section 165. Because the horizontal cross-sectional dimension of the first contraction section 164 gradually decreases from top to bottom, the airflow velocity increases, creating a negative pressure at the second inlet 162 to draw in ethylene glycol.

[0050] The upper port cross-sectional dimension of the second contraction section 168 is larger than that of its lower port cross-sectional dimension, gradually decreasing from top to bottom; and the upper port cross-sectional dimension of the second diffusion section 1610 is smaller than that of its lower port cross-sectional dimension, gradually increasing from top to bottom. A central tube 1611 coaxial with the second contraction section 168 is provided inside the second contraction section 168, forming an annular space 1613 between the central tube 1611 and the second contraction section 168. The lower end opening of the central tube 1611 is reduced to form a constriction section 1612, which is located inside the second throat section 169.

[0051] In the first diffusion section 166, ethylene glycol and coalbed methane are mixed once. A portion of the fluid flows towards the inner wall of the connecting pipe 167 and enters the annular space 1613. The other portion of the fluid enters the central pipe 1611 and is accelerated at the constriction 1612 at the lower end of the central pipe 1611. As a result, the fluid flowing out of the annular space 1613 to the second throat section 169 undergoes secondary mixing with the fluid flowing out of the central pipe 1611 to the second throat section 169, which is beneficial for the full and uniform mixing of ethylene glycol and coalbed methane.

[0052] During the above mixing process, ethylene glycol absorbs moisture from the coalbed methane, separating the coalbed methane from the water vapor. After the first dehumidification and pressurization of the coalbed methane in the first separation section 100, the second separation section 200 mixes the pressurized coalbed methane with ethylene glycol twice, significantly improving the dehumidification effect of the coalbed methane.

[0053] Figure 4 This is a schematic diagram of the separator 17 in a separation device for producing coalbed methane by carbon dioxide displacement according to an embodiment of the present invention. Figure 5 This is a cross-sectional view of separator 17 in a separation device for producing coalbed methane by carbon dioxide displacement, according to an embodiment of the present invention.

[0054] like Figure 1 , Figure 4 and Figure 5As shown, separator 17 is used to separate the mixed and dehumidified coalbed methane from ethylene glycol. Separator 17 includes a shell section 170, which is cylindrical. The outer contour of the shell section 170 has a tangential inlet 171, through which the mixed fluid flows in. The top of the shell section 170 has a gas outlet 21 from which the coalbed methane is discharged; the bottom of the shell section 170 has a liquid outlet 172 from which ethylene glycol is discharged.

[0055] A filter section 173 is provided inside the housing section 170. The filter section 173 is located above the tangential inlet 171. The coal seam gas flows through the filter section 173 and then flows to the gas outlet 21 to filter out the liquid droplets carried in the gas flow.

[0056] The shell portion 170 is also provided with a funnel portion 174. Ethylene glycol flowing in from the tangential inlet 171 forms a swirling flow on the inner wall of the shell portion 170 and gathers inside the funnel portion 174. Under its own weight, it flows out from the lower port of the funnel portion 174 to the liquid outlet 172.

[0057] See again Figure 1 Ethylene glycol flowing out of liquid outlet 172 passes through ethylene glycol regenerator 18 to remove adsorbed water and then enters storage container 19. The second inlet 162 of mixer 16 is connected to storage container 19 through a pipeline and is used to extract ethylene glycol from storage container 19.

[0058] The ethylene glycol regenerator 18 is existing technology. For example, Chinese utility model patents CN205347274U, CN220989705U, and CN215517219U have disclosed related technologies, which will not be repeated in this application.

[0059] Figure 6 This is a schematic diagram of a separation device for producing coalbed methane using carbon dioxide displacement, according to an embodiment of the present invention, applied to coalbed methane extraction.

[0060] like Figure 6 As shown, during the operation of the separation unit for producing coalbed methane using carbon dioxide displacement, carbon dioxide is injected into the coal seam through injection well 23, and the gas inlet 20 of the separation unit is connected to the production well 24. Coalbed methane to be treated is drawn in through gas inlet 20, undergoes preliminary dehumidification and pressurization, and then is transported to the second separation section 200. In the second separation section 200, the coalbed methane is mixed with ethylene glycol. After the ethylene glycol adsorbs water vapor from the coalbed methane, the gas and ethylene glycol are separated, thus achieving the drying and dehumidification of the coalbed methane.

[0061] The apparatus of this application has been described in detail with reference to the preferred technical solutions. However, it should be noted that, without departing from the spirit of this application, those skilled in the art can make any modifications, alterations, and variations based on the above disclosure. This application includes the above-described specific embodiments and any equivalent forms thereof.

Claims

1. A separation device for producing coalbed methane using carbon dioxide displacement, characterized in that, include: The first separation section (100) and the second separation section (200) include a first cylinder (1), a second cylinder (2), a third cylinder (3), a circulation pump (4), and a flow direction adjustment valve (5). The gas inlet (20) is connected to the top of the first cylinder (1) through the first inflow check valve (9) to unidirectionally supply coalbed methane to be processed to the first cylinder (1), and the gas inlet (20) is connected to the top of the second cylinder (2) through the second inflow check valve (10) to unidirectionally supply coalbed methane to be processed to the second cylinder (2). The top of the first cylinder (1) is connected to the bottom of the third cylinder (3) through a first outflow one-way valve (11) for unidirectional delivery of coalbed methane to the third cylinder (3); the top of the second cylinder (2) is connected to the bottom of the third cylinder (3) through a second outflow one-way valve for unidirectional delivery of coalbed methane to the third cylinder (3). One end of the circulating pump (4) is connected to the bottom of the first cylinder (1) through the flow direction adjustment valve (5), and the other end of the circulating pump (4) is connected to the bottom of the second cylinder (2) through the flow direction adjustment valve (5). The first cylinder (1), the second cylinder (2) and the third cylinder (3) are provided with a dehydrating agent; The flow direction regulating valve (5) has a first working state and a second working state. In the first working state, the circulating pump (4) is drawn out from the first cylinder (1) and pumps the drawn-out dehydrating agent into the second cylinder (2); the first cylinder (1) draws in coalbed methane and the second cylinder (2) discharges coalbed methane into the third cylinder (3). In the second working state, the circulating pump (4) extracts the dehydrating agent from the second cylinder (2) and pumps the extracted dehydrating agent into the first cylinder (1); the second cylinder (2) draws in coalbed methane, and the first cylinder (1) discharges the coalbed methane into the third cylinder (3). The second separation section (200) includes a mixer (16) and a separator (17). The third cylinder (3) is connected to the mixer (16) through a connecting pipe (22). The coalbed methane in the third cylinder (3) flows sequentially through the mixer (16) and the separator (17) through the connecting pipe (22), mixes with ethylene glycol in the mixer (16), and separates from ethylene glycol in the separator (17).

2. The separation device for producing coalbed methane by carbon dioxide displacement as described in claim 1, characterized in that, The flow direction regulating valve (5) is a two-position four-way solenoid directional valve.

3. The separation device for producing coalbed methane by carbon dioxide displacement as described in claim 2, characterized in that, It also includes a controller (6), a first liquid level sensor (13), and a second liquid level sensor (14). The first liquid level sensor (13) is installed on the top of the first cylinder (1) and is used to detect the liquid level of the dehydrating agent in the first cylinder (1); The second liquid level sensor (14) is installed on the top of the second cylinder (2) and is used to detect the liquid level of the dehydrating agent in the second cylinder (2); The controller (6) is connected to the first liquid level sensor (13), the second liquid level sensor (14), and the flow direction adjustment valve (5) respectively. The liquid level of the dehydrating agent in the first cylinder (1) has a first high level and a first low level; The liquid level of the dehydrating agent in the second cylinder (2) has a second high level and a second low level; The controller (6) is configured to, In the first working state, when the liquid level height of the dehydrating agent in the first cylinder (1) detected by the first liquid level sensor (13) reaches the first low level, and the liquid level height of the dehydrating agent in the second cylinder (2) detected by the second liquid level sensor (14) reaches the second liquid level, the flow direction adjustment valve (5) is controlled to switch from the first working state to the second working state. In the second working state, when the liquid level of the dehydrating agent in the second cylinder (2) detected by the second liquid level sensor (14) reaches the second low level, and the liquid level of the dehydrating agent in the first cylinder (1) detected by the first liquid level sensor (13) reaches the first high level, the flow direction adjustment valve (5) is controlled to switch from the second working state to the first working state.

4. The separation device for producing coalbed methane by carbon dioxide displacement as described in claim 3, characterized in that, It also includes a first delivery pump (7), one end of which is connected to the bottom of the first cylinder (1), and the other end is connected to the bottom of the third cylinder (3); The controller (6) is signal-connected to the first delivery pump (7); The controller (6) is configured to, in the first operating state, When the liquid level in the second cylinder (2) reaches the second highest level, if the liquid level in the first cylinder (1) does not drop to the first lowest level, it is determined that there is too much dehydrating agent in the circulation. The controller (6) starts the first delivery pump (7) to deliver the dehydrating agent in the first cylinder (1) to the third cylinder (3). When the liquid level in the first cylinder (1) drops to the first low level and the liquid level in the second cylinder (2) does not reach the second high level, it is determined that there is too little dehydrating agent in the uncirculated liquid. The controller (6) starts the first delivery pump (7) to deliver the dehydrating agent in the third cylinder (3) to the first cylinder (1).

5. The separation device for producing coalbed methane by carbon dioxide displacement as described in claim 4, characterized in that, It also includes a second transfer pump (8) and a third level sensor (15). The third liquid level sensor (15) is installed on the third cylinder (3) and is used to detect the liquid level height inside the third cylinder (3); The controller (6) is connected to the second delivery pump (8) and the third liquid level sensor (15) respectively; The second delivery pump (8) is connected to the bottom of the third cylinder (3) and is used to extract or deliver medium into the third cylinder (3); The controller (6) is configured to control the second delivery pump (8) to deliver medium into the third cylinder (3) when the liquid level height detected by the third liquid level sensor (15) is lower than the first preset height; and to control the second delivery pump (8) to extract medium from the third cylinder (3) when the liquid level height in the third cylinder (3) is higher than the second preset height.

6. The separation device for producing coalbed methane by carbon dioxide displacement as described in claim 5, characterized in that, The mixer (16) has a first inlet (161), a second inlet (162) and a mixing outlet (163). The first inlet (161) is connected to the upper part of the third cylinder (3) through the connecting pipe (22) for the coalbed methane pressurized by the first separation section (100) to flow into the first inlet (161) through the connecting pipe (22); the second inlet (162) is used to draw in ethylene glycol; after the ethylene glycol and coalbed methane are mixed, they flow out through the mixing outlet (163).

7. The separation device for producing coalbed methane by carbon dioxide displacement as described in claim 6, characterized in that, The mixer (16) has a mixing tube (160) which is provided with a first contraction section (164), a first throat section (165), a first diffusion section (166), a connecting tube (167), a second contraction section (168), a second throat section (169), and a second diffusion section (1610) from top to bottom. The first throat segment (165) is connected to the storage container (19) through the second inlet (162); The upper port cross-sectional dimension of the first contraction section (164) is larger than the lower port cross-sectional dimension, and gradually decreases from top to bottom; and the upper port dimension of the first diffusion section (166) is smaller than the lower port cross-sectional dimension, and gradually increases from top to bottom. The second inlet (162) is connected to the first throat segment (165) to create a negative pressure at the second inlet (162) to draw in ethylene glycol.

8. The separation device for producing coalbed methane by carbon dioxide displacement as described in claim 7, characterized in that, The upper port cross-sectional dimension of the second contraction section (168) is larger than the lower port cross-sectional dimension, and gradually decreases from top to bottom; and the upper port dimension of the second diffusion section (1610) is smaller than the lower port cross-sectional dimension, and gradually increases from top to bottom. The second contraction section (168) is provided with a central tube (1611) coaxial with it, and an annular space (1613) is formed between the central tube (1611) and the second contraction section (168). The lower end opening size of the central tube (1611) is reduced to form a constricted part (1612), and the constricted part (1612) is located in the second throat section (169).

9. The separation device for producing coalbed methane by carbon dioxide displacement as described in claim 8, characterized in that, The separator (17) includes a shell section (170) which is cylindrical. The outer contour of the shell section (170) has a tangential inlet (171) through which the mixed fluid flows in. The top of the shell section (170) is a gas outlet (21) through which coalbed methane is discharged. The bottom of the shell section (170) has a liquid outlet (172) through which ethylene glycol is discharged.

10. The separation device for producing coalbed methane by carbon dioxide displacement as described in claim 9, characterized in that, A filter section (173) is provided inside the housing portion (170), and the filter section (173) is located above the tangential inlet (171); The shell section (170) is further provided with a funnel section (174). Ethylene glycol flowing in from the tangential inlet (171) forms a swirling flow on the inner wall of the shell section (170) and gathers inside the funnel section (174). Under its own weight, it flows out from the lower port of the funnel section (174) to the liquid outlet (172).

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