Cascade pipe column gas-liquid separation device

Abstract

The application is a kind of cascade pipe column type gas-liquid separation device, which comprises a primary separation pipe column structure, a lower cylinder, at least one tangential inlet arranged at the top of the side wall of the lower cylinder, a flow guide cylinder arranged in the lower cylinder, a first annular space formed between the flow guide cylinder and the lower cylinder, a secondary separation pipe column structure, an upper cylinder, a gas phase outlet arranged at the top of the upper cylinder, an inner pipe column arranged in the upper cylinder and extending downward through the flow guide cylinder, the top of the inner pipe column being closed, an inner pipe side outlet arranged at the top of the side wall of the inner pipe column, the inner pipe column and the flow guide cylinder being spaced apart to form a second annular space, a drain pipe arranged at the center of the cascade pipe column type gas-liquid separation device, and the bottom end of the drain pipe being connected to an electric submersible pump. The application adopts a multi-stage separation pipe column structure to perform multiple cyclone separation on natural gas production gas. An annular gap is arranged between the inner pipe column and the flow guide cylinder, a backflow liquid film is formed by the downward flowing liquid through the annular gap, and the gas phase liquid carrying phenomenon is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development technology, and in particular to a cascaded tubular gas-liquid separation device. Background Technology

[0002] Natural gas hydrates, high-pressure gas (water-soluble gas), and deep gas represent a vast unconventional natural gas resource potential with broad development prospects. However, natural gas extraction is currently relatively limited, requiring further research into new technologies and addressing various challenges encountered during extraction. With the advancement of oil and gas exploration and development technologies, the effective extraction of unconventional natural gas will inevitably be achieved. This is increasingly important for meeting the growing energy demand, and unconventional natural gas will undoubtedly become a new generation of environmentally friendly, efficient, and high-quality alternative energy. Natural gas hydrates are widely distributed in nature on the slopes of continents and islands, at the uplifted edges of active and passive continental margins, on polar continental shelves, and in the deep-water environments of oceans and some inland lakes.

[0003] Natural gas extraction inevitably involves dehydration and purification. In petrochemical plants, various gas-phase dehydration equipment is used, among which tubular gas-liquid separators are widely used in various gas-liquid separation applications due to their advantages such as simple and compact structure, light weight, low energy consumption, low price, excellent performance, convenient operation, simple maintenance, and easy installation. Tubular gas-liquid separators utilize a separation mechanism coupled with centrifugal and gravitational forces, giving them high separation efficiency. However, current tubular gas-liquid separators generally suffer from gas-phase liquid carryover, resulting in poor liquid-phase separation efficiency and limiting their engineering applications.

[0004] Therefore, based on years of experience and practice in related industries, the inventor proposes a cascaded tubular gas-liquid separation device to overcome the shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a cascaded tubular gas-liquid separator, which employs a multi-stage separation tubular structure to perform multiple cyclone separations on the produced natural gas. An annular gap is provided between the inner tubular column and the guide cylinder, allowing the liquid phase discharged into the upper cylinder to return to the lower cylinder through the annular gap, thus completing the gas-liquid separation. Furthermore, the liquid flow flowing downward through the annular gap forms a reflux liquid film, preventing the produced natural gas from directly entering the inner tubular column in a short-circuit flow manner, thereby significantly reducing the phenomenon of liquid carrying by the gas phase and improving the separation efficiency. A drain pipe is provided at the axis of the entire gas-liquid separator, acting as a central flow stabilizer, which makes the cyclone field inside the lower cylinder and the inner tubular column more stable, ensuring the cyclone separation effect.

[0006] The objective of this invention is achieved by providing a cascaded tubular gas-liquid separation device, comprising:

[0007] The first-stage separation tubing structure includes a lower cylinder closed at both ends. At least one tangential inlet is provided at the top of the side wall of the lower cylinder. A guide tube is coaxially arranged inside the lower cylinder at the position corresponding to the tangential inlet. The two ends of the guide tube are open. The guide tube and the lower cylinder form a first annular space that can strongly swirl the produced natural gas.

[0008] The two-stage separation column structure includes an upper cylinder connected to the lower cylinder at its bottom end, the upper cylinder and the lower cylinder forming an outer column; a gas phase outlet is provided at the top of the upper cylinder, and an inner column extending downward through the guide tube is provided inside the upper cylinder, the top of the inner column being closed, and an inner tube side outlet being provided at the top of the side wall of the inner column; the inner column and the guide tube are spaced apart to form a second annular space, the second annular space being able to communicate with the inner cavities of the upper cylinder and the lower cylinder;

[0009] The drain pipe is located at the axis of the cascaded tubular gas-liquid separator, extending upward from the bottom of the lower cylinder through the lower cylinder, the inner tubular column, the upper cylinder, and the gas phase outlet. The bottom end of the drain pipe is connected to an electric submersible pump that provides the power for draining.

[0010] In a preferred embodiment of the present invention, a variable diameter section is provided on the outer wall of the drain pipe at the connection between the upper cylinder and the lower cylinder, and a swirl-generating blade capable of strongly swirling the natural gas produced is provided between the variable diameter section and the inner pipe column.

[0011] In a preferred embodiment of the present invention, an arc-shaped plate is connected to the outer wall of the lower cylinder at the position of the tangential inlet. The flow channel area between the inner wall of the arc-shaped plate and the outer wall of the lower cylinder is gradually reduced. The natural gas produced is guided and accelerated by the arc-shaped plate and enters the first annular space through the tangential inlet to form a strong swirling flow so as to separate the gas and liquid phases.

[0012] In a preferred embodiment of the present invention, the central angle of the tangential inlet along the circle containing the cross-section of the lower cylinder is greater than 60° and less than 90°.

[0013] In a preferred embodiment of the present invention, an upper baffle is provided at the top of the lower cylinder, and a connecting hole is provided on the upper baffle, at which the downwardly extending guide cylinder is connected; a lower baffle is provided on the outer wall of the lower cylinder below the tangential inlet, and an inlet flow channel is formed between the lower baffle, the arc-shaped plate and the upper baffle, and the cross-sectional area of ​​the inlet flow channel is gradually reduced.

[0014] In a preferred embodiment of the present invention, the radial width of the second annular space is less than 1 / 5 of the inner diameter of the guide tube, and the length of the bottom end of the inner tube extending out of the guide tube is greater than 1 / 5 of the inner diameter of the guide tube and less than 2 / 3 of the inner diameter of the guide tube.

[0015] In a preferred embodiment of the present invention, a baffle plate is provided at the top of the inner tube column, and the outer diameter of the baffle plate is larger than the outer diameter of the inner tube column.

[0016] In a preferred embodiment of the present invention, a cone with a diameter that gradually decreases from top to bottom is provided in the lower cylinder below the guide cylinder, the bottom end of the cone is connected to the underflow pipe, and the electric submersible pump is provided below the underflow pipe.

[0017] In a preferred embodiment of the present invention, a top cover plate is provided at the top of the upper cylinder, and a gas phase outlet pipe communicating with the inner cavity of the upper cylinder is provided at the center of the top cover plate, and the inner cavity of the gas phase outlet pipe constitutes the gas phase outlet.

[0018] In a preferred embodiment of the present invention, the variable diameter section includes a lower conical section with a diameter that gradually increases from bottom to top, the top end of the lower conical section is connected to a cylindrical section, and the top end of the cylindrical section is connected to an upper conical section with a diameter that gradually decreases from bottom to top; the swirl-generating blade is disposed between the cylindrical section and the inner tube column.

[0019] As described above, the cascaded tubular gas-liquid separator of the present invention has the following beneficial effects:

[0020] In the cascaded tubular gas-liquid separator of this invention, a multi-stage separation tubular structure is adopted to perform multiple swirling separations on the produced natural gas. An annular gap is provided between the inner tubular column and the guide cylinder. The liquid phase that enters the inner tubular column with the gas phase and is discharged into the inner space of the upper cylinder from the inner tube side outlet can return to the lower cylinder through the annular gap to complete the gas-liquid separation. Moreover, the liquid flow flowing downward through the annular gap forms a reflux liquid film, preventing the produced natural gas from directly entering the inner tubular column in the form of a short-circuit flow, thereby significantly reducing the phenomenon of liquid carrying by the gas phase and improving the separation efficiency. A drain pipe is set at the axis of the entire gas-liquid separator, which acts as a central flow stabilizer, making the swirling field inside the lower cylinder and the inner tubular column more stable and ensuring the swirling separation effect. Attached Figure Description

[0021] The accompanying drawings are intended only to illustrate and explain the present invention and do not limit the scope of the invention.

[0022] in:

[0023] Figure 1 : This is a schematic diagram of the cascaded tubular gas-liquid separation device of the present invention.

[0024] Figure 2 :for Figure 1 Sectional view of AA.

[0025] Figure 3 :for Figure 1 BB section view.

[0026] In the picture:

[0027] 101. First annular space; 102. Second annular space;

[0028] 1. Gas phase outlet pipe; 2. Top cover plate; 3. Flange; 4. Anti-blow plate; 5. Upper cylinder; 6. Inner tube column; 7. Upper baffle; 8. Flow guide tube; 9. Lower baffle; 10. Lower cylinder; 11. Conical cylinder; 12. Underflow pipe; 13. Arc plate; 14. Drain pipe; 15. Variable diameter section; 16. Swirl-generating blade; 17. Electric submersible pump; 18. Tangential inlet; 19. Gas phase outlet; 20. Inner tube side outlet. Detailed Implementation

[0029] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0030] The specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the invention in any way. Under the teachings of this invention, those skilled in the art can conceive of any possible modifications based on the invention, all of which should be considered within the scope of the invention. It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "mounted," "connected," and "linked" should be interpreted broadly; for example, they can refer to mechanical or electrical connections, or internal communication between two elements, and can be direct or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] like Figure 1 , Figure 2 , Figure 3 As shown, the present invention provides a cascaded tubular gas-liquid separator, comprising,

[0033] The first-stage separation tubing structure includes a lower cylinder 10 closed at both ends. At least one tangential inlet 18 is provided at the top of the side wall of the lower cylinder 10. A guide tube 8 is coaxially arranged inside the lower cylinder 10 at the position corresponding to the tangential inlet 18. The two ends of the guide tube 8 are open. The guide tube 8 and the lower cylinder 10 form a first annular space 101 that can strongly swirl the natural gas produced.

[0034] The two-stage separation column structure includes an upper cylinder 5 connected to the lower cylinder 10 at its bottom end, the upper cylinder 5 and the lower cylinder 10 forming an outer column; the upper cylinder 5 and the lower cylinder 10 are coaxially arranged; a gas phase outlet 19 is provided at the top of the upper cylinder 5; an inner column 6 is provided inside the upper cylinder 5, extending downward through the guide tube 8; the top of the inner column 6 is closed; an inner tube side outlet 20 is provided at the top of the side wall of the inner column 6; the inner column 6 and the guide tube 8 are spaced apart to form a second annular space 102, the second annular space 102 can connect the inner cavities of the upper cylinder 5 and the lower cylinder 10;

[0035] The drain pipe 14 is located at the axis of the cascaded tubular gas-liquid separator. It extends upward from the bottom of the lower cylinder 10, passing through the lower cylinder 10, the inner tubular column 6, the upper cylinder 5, and the gas phase outlet 19. The bottom of the drain pipe 14 is connected to the electric submersible pump 17 that provides the power for draining.

[0036] The outer tube column is composed of an upper cylinder 5 and a lower cylinder 10. The entire outer tube column can be set up in three dimensions, and according to the actual working conditions, support components can be added at the bottom of the outer tube column to enhance the stability of the gas-liquid separation device.

[0037] The connection between the upper cylinder 5 and the lower cylinder 10 is located in the middle of the outer tube column. The tangential inlet 18 is set at this position. One or two tangential inlets 18 can be set, and the number is determined according to the actual working conditions.

[0038] Produced natural gas enters the first annular space 101 through a tangential inlet, forming a strong vortex to separate the gas and liquid phases. The heavy phase water gradually accumulates on the inner wall of the lower cylinder 10 under centrifugal force and converges downwards under gravity, while the light phase natural gas flows back upwards to form a core flow (the bottom of the lower cylinder 10 is closed, allowing the natural gas to flow back upwards to form a core flow), and enters the inner tube column 6, flowing upwards along the inner tube column 6, forming a strong vortex field again within the inner tube column 6. The separation effect of the strong vortex field and the impact of the natural gas with the closed top of the inner tube column further achieves the aggregation and separation of the liquid phase components in the natural gas; and the vortex field inside the lower cylinder 10 and the inner tube column 6 is further stabilized by the flow-guiding effect of the central drain pipe 14.

[0039] The gas phase discharged from the inner tube side outlet 20 of the inner tube column 6 continues to flow upward inside the upper cylinder 5 and is eventually discharged from the gas phase outlet 19. The liquid phase discharged from the inner tube side outlet 20 of the inner tube column 6 flows downward under the action of gravity and flows down from the second annular space 102 (annular gap) between the inner tube column 6 and the guide tube 8 to the inner space of the lower cylinder 10. Finally, it gathers at the bottom of the lower cylinder 10 and is driven by the electric submersible pump 17 to be discharged from the top through the drain pipe 14, thus completing the separation of the gas phase and liquid phase in the natural gas produced gas. The liquid flow flowing downward through the second annular space 102 (annular gap) forms a reflux liquid film, preventing the natural gas produced gas from directly entering the inner tube column 6 in the form of a short-circuit flow, thereby greatly reducing the phenomenon of gas phase carrying liquid and improving the separation efficiency.

[0040] In the cascaded tubular gas-liquid separator of the present invention, a multi-stage separation tubular structure is adopted to perform multiple swirling separations on the produced natural gas. An annular gap (second annular space 102) is provided between the inner tubular column 6 and the guide cylinder 8. The liquid phase that enters the inner tubular column 6 with the gas phase and is discharged into the inner space of the upper cylinder 5 from the inner tube side outlet 20 can return to the lower cylinder 10 through the annular gap to complete the gas-liquid separation. The liquid flow flowing downward through the annular gap forms a reflux liquid film, preventing the produced natural gas from directly entering the inner tubular column 6 in the form of a short-circuit flow, thereby greatly reducing the liquid-carrying phenomenon of the gas phase and improving the separation efficiency. A drain pipe 14 is provided at the axis of the entire gas-liquid separator, which acts as a central flow stabilizer, making the swirling field inside the lower cylinder 10 and the inner tubular column 6 more stable and ensuring the swirling separation effect.

[0041] Furthermore, such as Figure 1 As shown, a variable diameter section 15 is provided on the outer wall of the drain pipe 14 at the connection between the upper cylinder 5 and the lower cylinder 10. A swirl-generating blade 16, which can strongly swirl the produced natural gas, is provided between the variable diameter section 15 and the inner tubing 6. The swirl-generating blade 16 enhances the rotation intensity of the swirling flow field inside the inner tubing 6, thereby enhancing the secondary separation effect.

[0042] The variable diameter section 15 is a solid structure, which expands the inner diameter of the annular flow channel between the drain pipe 14 and the inner tube column 6, thereby reducing the flow area. A swirl-generating blade 16 is provided between the variable diameter section 15 and the inner tube column 6. The swirl-generating blade 16 swirls the rising flow in the inner tube column 6 (generated by the action of the cone 11) again to generate enhanced swirling separation and enhance the separation efficiency of the entire gas-liquid separation device.

[0043] In a specific embodiment of the present invention, the variable diameter section 15 includes a lower conical section with a diameter that gradually increases from bottom to top, the top end of the lower conical section is connected to a cylindrical section, and the top end of the cylindrical section is connected to an upper conical section with a diameter that gradually decreases from bottom to top; a swirl-generating blade 16 (using existing technology) is provided between the cylindrical section and the inner tube column 6.

[0044] Furthermore, such as Figure 1 , Figure 2 As shown, an arc-shaped plate 13 is connected to the outer wall of the lower cylinder 10 at the position of the tangential inlet 18. The flow channel area between the inner wall of the arc-shaped plate 13 and the outer wall of the lower cylinder 10 is gradually reduced. The natural gas produced is guided by the arc-shaped plate 13 to rotate and accelerate through the tangential inlet 18 into the first annular space 101 to form a strong swirling flow so as to separate the gas and liquid phases.

[0045] The tangential inlet 18 is a rectangular opening provided on the side wall of the lower cylinder 10. One side of the rectangular opening extends and is connected to an arc-shaped plate 13. The arc-shaped plate 13 is tangentially connected to the outer wall surface of the lower cylinder 10 and extends outward from the tangential connection point to completely cover the tangential inlet and continues to extend a certain distance. In this embodiment, the arc-shaped plate 13 extends outward from the tangential connection point with the outer wall surface of the lower cylinder 10 to cover a 90-degree angle range, thereby covering the tangential inlet 18.

[0046] An inlet for natural gas extraction is formed between the outer wall of the lower cylinder 10 and the side of the arc plate 13 away from the lower cylinder 10. The flow channel area between the inlet and the tangential inlet 18 gradually decreases. After entering through the inlet, the natural gas extraction is first guided by the arc plate 13, thus rotating into the tangential inlet 18 of the lower cylinder 10. Under the influence of the gradually decreasing flow channel area, the flow velocity of the natural gas extraction increases, forming a strong swirling flow in the first annular space 101 (between the inner wall of the lower cylinder 10 and the guide tube 8), thereby achieving gas-liquid two-phase separation.

[0047] Furthermore, one or two tangential inlets 18 are provided. In one specific embodiment, two tangential inlets 18 are provided. The two tangential inlets 18 are distributed with rotational symmetry at points along the central axis of the lower cylinder 10, and the central angle α of the rectangular opening of each tangential inlet 18 along the circle containing the cross-section of the lower cylinder 10 is greater than 60° and less than 90°. Figure 2 As shown, is Figure 1 The sectional view AA, which omits the view structure of the drain pipe 14 and the electric submersible pump 17, specifically shows the tangential inlet structure of the cascaded tubular gas-liquid separation device of the present invention. Figure 2 A schematic diagram of an embodiment with two tangential inlets 18 is shown, the two tangential inlets 18 being rotationally symmetrically distributed along the central axis of the outer tube (lower cylinder 10).

[0048] In this specific embodiment, a line is drawn from the side of the tangential inlet 18 that is not tangentially connected to the arc-shaped plate 13 downwards to the center of the cylinder 10. This line is connected to... Figure 2 The angle between the horizontal center lines is 28°, that is, the line connecting the side of the tangential inlet 18 that is tangentially connected to the arc plate 13 downward to the center of the cylinder 10, and the line connecting the other side that is not in contact with the arc plate 13 downward to the center of the cylinder 10, the included angle between the two connecting lines is greater than 60°.

[0049] Furthermore, such as Figure 1 As shown, an upper baffle 7 is provided at the top of the lower cylinder 10, and a connecting hole is provided on the upper baffle 7. A downwardly extending guide cylinder 8 is connected to the connecting hole. A lower baffle 9 is provided on the outer wall of the lower cylinder 10 below the tangential inlet 18. The lower baffle 9, the arc plate 13 and the upper baffle 7 form an inlet flow channel, and the cross-sectional area of ​​the inlet flow channel is gradually reduced.

[0050] The present invention redesigns the structure of the tangential inlet, using the structure of the arc plate to form a funnel-shaped flow channel with a gradually decreasing flow area. After the natural gas produced enters from the inlet, it is first guided by the arc plate, thus rotating into the tangential inlet 18 of the lower cylinder 10. Under the influence of the gradually decreasing flow channel area, the flow velocity of the natural gas produced increases, thereby improving the swirling intensity and improving the separation efficiency.

[0051] Furthermore, the inner tube column 6 is connected and fixed to the guide tube 8 by a support rod to achieve the positioning of the inner tube column 6 inside the outer tube column.

[0052] Furthermore, the radial width of the second annular space 102 is less than 1 / 5 of the inner diameter of the guide tube, and the length of the bottom end of the inner tube extending out of the guide tube is greater than 1 / 5 of the inner diameter of the guide tube and less than 2 / 3 of the inner diameter of the guide tube.

[0053] In a specific embodiment of the present invention (DN100 pilot test device), the inner diameter of the outer column (upper cylinder 5 and lower cylinder 10) is 100 mm, the inner diameter of the guide tube 8 is 58 mm, the inner diameter of the inner column is 40 mm, the radial width of the second annular space 102 is 5 mm, and the length of the lower end of the inner column 6 extending out of the guide tube 8 is 20 mm. Under these size constraints, the pilot device basically eliminates the phenomenon of liquid carrying, and the gas-liquid separation efficiency is greatly improved compared with the traditional column-type gas-liquid separation equipment.

[0054] Furthermore, such as Figure 1 As shown, a baffle plate 4 is installed at the top of the inner tubular column 6. The outer diameter of the baffle plate 4 is larger than the outer diameter of the inner tubular column 6. The baffle plate 4 seals the top of the inner tubular column 6.

[0055] In one specific embodiment, two inner tube side outlets 20 are symmetrically arranged on the side wall of the inner tube column 6. For example... Figure 3 The diagram shown (excluding the view of the drain pipe 14, the variable diameter section 15, and the swirl-generating blade 16) illustrates the structural relationship of the two inner tube side outlets 20 at the top of the side wall of the inner tube column.

[0056] The rising natural gas flow inside the inner tube column 6 (at the center of the cascaded tube gas-liquid separator of the present invention) is blocked by the baffle plate 4 and flows out of the inner tube column 6 from the two inner tube side outlets 20. Under the impact of the baffle plate 4, the accumulation and descent of the trace liquid phase carried in the gas phase is promoted, thereby enhancing the separation effect.

[0057] Furthermore, such as Figure 1 As shown, a cone 11 with a diameter that gradually decreases from top to bottom is provided inside the lower cylinder 10 below the guide tube 8. The bottom end of the cone 11 is connected to the underflow pipe 12, and an electric submersible pump 17 is provided below the underflow pipe 12.

[0058] Furthermore, such as Figure 1 As shown, a top cover plate 2 is provided at the top of the upper cylinder 5, and the top cover plate 2 is connected to the upper cylinder 5 through a flange 3; a gas phase outlet pipe 1 is provided at the center of the top cover plate 2, which communicates with the inner cavity of the upper cylinder 5, and the inner cavity of the gas phase outlet pipe 1 constitutes a gas phase outlet 19.

[0059] The drain pipe 14 is located at the axis of the entire cascaded tube column gas-liquid separation device. The top end of the drain pipe 14 passes through the gas phase outlet pipe 1 and is connected to the external pipeline or equipment to discharge the liquid phase. The lower end of the drain pipe 14 is connected to the electric submersible pump 17 installed at the bottom of the outer tube column (lower cylinder 10). The electric submersible pump 17 provides the power for the liquid phase to be discharged from the upper end.

[0060] The working principle of the cascaded tubular gas-liquid separator of the present invention is as follows:

[0061] Natural gas produced enters through the two tangential inlets 18 of this invention. Under the guidance and swirling effect of the arc plate 13 and the constraint of the flow channel structure with the gradually shrinking flow area between the arc plate 13 and the outer tube wall, it enters the first annular space 101 (the annular space between the outer tube and the guide cylinder 8) and forms a strong swirling flow. The heavy phase water gradually gathers on the inner wall of the outer tube under centrifugal force and collects downward under gravity. The light phase natural gas flows back upward to form a core flow and enters the inner tube 6. It flows upward along the inner tube 6 and forms a strong swirling flow field again. The swirling flow is further enhanced by the swirling blades 16. Under the separation effect of the strong swirling flow field and the impact stop effect of the natural gas with the anti-impact plate 4 at the top of the inner tube, the aggregation and separation of the liquid phase components in the natural gas are further realized. Moreover, under the stabilizing and guiding effect of the drain pipe 14 at the axis, the entire swirling flow field in the lower cylinder 10 and the inner tube 6 is more stable.

[0062] The gas phase discharged from the inner tube side outlet 20 (side outlet near the upper end) of the inner tube column 6 continues to flow upward inside the upper cylinder 5 and is eventually discharged from the gas phase outlet pipe 1. The liquid phase discharged from the inner tube side outlet 20 of the inner tube column 6 flows downward under the action of gravity and flows down from the second annular space 102 (the annular gap between the inner tube column 6 and the guide tube 8) to the inner space of the lower cylinder 10. Finally, it collects in the underflow pipe 12 and is discharged to the bottom of the lower cylinder 10. Driven by the electric submersible pump 17, it is discharged from the upper end through the drain pipe 14, completing the separation of the gas phase and liquid phase in the natural gas produced gas. The liquid flow flowing downward through the annular gap forms a reflux liquid film, preventing the natural gas produced gas from directly entering the inner tube column in the form of a short-circuit flow, thereby greatly reducing the phenomenon of gas phase carrying liquid and improving the separation efficiency.

[0063] As described above, the cascaded tubular gas-liquid separator of the present invention has the following beneficial effects:

[0064] In the cascaded tubular gas-liquid separator of this invention, a multi-stage separation tubular structure is adopted to perform multiple swirling separations on the produced natural gas. An annular gap is provided between the inner tubular column and the guide cylinder. The liquid phase that enters the inner tubular column with the gas phase and is discharged into the inner space of the upper cylinder from the inner tube side outlet can return to the lower cylinder through the annular gap to complete the gas-liquid separation. Moreover, the liquid flow flowing downward through the annular gap forms a reflux liquid film, preventing the produced natural gas from directly entering the inner tubular column in the form of a short-circuit flow, thereby significantly reducing the phenomenon of liquid carrying by the gas phase and improving the separation efficiency. A drain pipe is set at the axis of the entire gas-liquid separator, which acts as a central flow stabilizer, making the swirling field inside the lower cylinder and the inner tubular column more stable and ensuring the swirling separation effect.

[0065] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A cascaded tubular gas-liquid separation device, characterized in that, include, The first-stage separation tubing structure includes a lower cylinder closed at both ends. At least one tangential inlet is provided at the top of the side wall of the lower cylinder. A guide tube is coaxially arranged inside the lower cylinder at the position corresponding to the tangential inlet. The two ends of the guide tube are open. The guide tube and the lower cylinder form a first annular space that can strongly swirl the produced natural gas. The two-stage separation column structure includes an upper cylinder connected to the lower cylinder at its bottom end, the upper cylinder and the lower cylinder forming an outer column; a gas phase outlet is provided at the top of the upper cylinder, and an inner column extending downward through the guide tube is provided inside the upper cylinder, the top of the inner column being closed, and an inner tube side outlet being provided at the top of the side wall of the inner column; the inner column and the guide tube are spaced apart to form a second annular space, the second annular space being able to communicate with the inner cavities of the upper cylinder and the lower cylinder; A drain pipe is located at the axis of the cascaded tubular gas-liquid separator, extending upward from the bottom of the lower cylinder through the lower cylinder, the inner tubular column, the upper cylinder, and the gas phase outlet. The bottom of the drain pipe is connected to an electric submersible pump that provides the power for draining. A variable diameter section is provided on the outer wall of the drain pipe at the connection between the upper cylinder and the lower cylinder, and a swirl-generating blade that can strongly swirl the natural gas produced is provided between the variable diameter section and the inner pipe column. An arc-shaped plate is connected to the outer wall of the lower cylinder at the tangential inlet. The flow channel area between the inner wall of the arc-shaped plate and the outer wall of the lower cylinder is gradually reduced. The natural gas produced is guided and accelerated by the arc-shaped plate and enters the first annular space through the tangential inlet to form a strong swirling flow so as to separate the gas and liquid phases.

2. The cascaded tubular gas-liquid separator as described in claim 1, characterized in that, The central angle of the tangential inlet along the circle containing the cross-section of the lower cylinder is greater than 60° and less than 90°.

3. The cascaded tubular gas-liquid separator as described in claim 1, characterized in that, An upper baffle is provided at the top of the lower cylinder, and a connecting hole is provided on the upper baffle. The connecting hole is connected to the downwardly extending guide cylinder. A lower baffle is provided on the outer wall of the lower cylinder below the tangential inlet. The lower baffle, the arc-shaped plate and the upper baffle form an inlet flow channel, and the cross-sectional area of ​​the inlet flow channel is gradually reduced.

4. The cascaded tubular gas-liquid separator as described in claim 1, characterized in that, The radial width of the second annular space is less than 1 / 5 of the inner diameter of the guide tube, and the length of the bottom end of the inner tube extending out of the guide tube is greater than 1 / 5 of the inner diameter of the guide tube and less than 2 / 3 of the inner diameter of the guide tube.

5. The cascaded tubular gas-liquid separator as described in claim 1, characterized in that, A baffle plate is provided at the top of the inner tube column, and the outer diameter of the baffle plate is larger than the outer diameter of the inner tube column.

6. The cascaded tubular gas-liquid separator as described in claim 1, characterized in that, The lower cylinder is located below the guide cylinder and has a tapered cylinder with a diameter that gradually decreases from top to bottom. The bottom end of the tapered cylinder is connected to the underflow pipe, and the electric submersible pump is located below the underflow pipe.

7. The cascaded tubular gas-liquid separator as described in claim 1, characterized in that, A top cover plate is provided at the top of the upper cylinder, and a gas phase outlet pipe communicating with the inner cavity of the upper cylinder is provided at the center of the top cover plate. The inner cavity of the gas phase outlet pipe constitutes the gas phase outlet.

8. The cascaded tubular gas-liquid separator as described in claim 1, characterized in that, The variable diameter section includes a lower conical section with a diameter that gradually increases from bottom to top, the top end of the lower conical section is connected to a cylindrical section, and the top end of the cylindrical section is connected to an upper conical section with a diameter that gradually decreases from bottom to top; the swirl-generating blade is disposed between the cylindrical section and the inner tube column.

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