A self-excited oscillation pulverized coal filtering system used in coalbed methane mining

Abstract

The invention discloses a self-excited oscillation filtration coal powder system used in the coalbed methane mining process, the system comprises: an outer cylinder seat, an end cover, a spring assembly, a filter assembly, an oscillation sheet, a water inlet pipe, a water outlet pipe and a sand pump; the outer cylinder seat is a cylindrical body with a chamber provided therein, and a hole is opened at the center of the bottom; the upper pipe opening of the water inlet pipe extends upward from the hole at the bottom of the outer cylinder seat into the inner cavity of the outer cylinder seat; the lower pipe opening of the water inlet pipe is downwardly connected to the coalbed methane mining well; the end cover sealing cover is closed at the upper end of the outer cylinder seat; the center of the end cover is provided with an air outlet connected to an external coalbed methane gas production pipeline; the end cover, the spring assembly, the filter assembly and the oscillation sheet are connected in sequence from top to bottom; the filter assembly surrounds the air outlet; the oscillation sheet is suspended directly above the pipe opening of the water inlet pipe; a water outlet is provided at the bottom of the outer cylinder seat; and the sand pump is connected to the water outlet through the water outlet pipe. The invention effectively separates coalbed methane from coal powder, and the coalbed methane and coal powder are collected separately, thereby improving the extraction efficiency.

Description

Technical Field

[0001] The invention relates to a coal powder filtering system, in particular to a self-excited oscillation coal powder filtering system used in the coalbed methane mining process. Background Art

[0002] At present, coal dust is produced in the process of coalbed methane mining. The mechanism of coal dust production is that the geological characteristics of the coal seam determine that it will produce coal dust during the process of engineering disturbance. The geological characteristics of the coal seam (such as coal rock components, inorganic mineral components, metamorphic degree, coal body structure, etc.) are the basic conditions for the production of coal dust, and engineering disturbances (such as fracturing, drilling, perforation, drainage and mining, etc.) are the inducing factors for the production of coal dust. In the process of drainage and pressure reduction in coalbed methane development, unreasonable drainage system, high drainage intensity, fast gas production growth rate, and bottom hole pressure fluctuations will also affect the production of coal dust. In the process of coalbed methane mining, coal dust needs to be collected and processed, otherwise it is easy to cause coal dust to deposit in the seepage channel and cause blockage. Once blockage occurs, not only does it require greater water power to drive the coal dust deposited in the channel and clear the seepage channel, but it is also easy to cause pump jamming and other phenomena, affecting the mining efficiency and mining performance of coalbed methane. Summary of the invention

[0003] In order to solve the technical problems existing in the known technology, the present invention provides a self-excited oscillation pulverized coal filtering system for separating coalbed methane from pulverized coal and collecting them separately for use in the coalbed methane mining process.

[0004] The technical solution adopted by the present invention to solve the technical problems existing in the known technology is: a self-excited oscillation pulverized coal filtering system for coalbed methane mining process, the system comprising: an outer cylinder seat, an end cover, a spring assembly, a filter assembly, an oscillating plate, a water inlet pipe, a water outlet pipe and a sand pump; the outer cylinder seat is a cylindrical body with a chamber provided therein, and a hole is opened at the center of the bottom; the upper pipe opening of the water inlet pipe extends upward from the opening at the bottom of the outer cylinder seat into the inner cavity of the outer cylinder seat; the lower pipe opening of the water inlet pipe is downwardly connected to the coalbed methane mining well; the end cover sealing cover is closed on the upper end of the outer cylinder seat; the center of the end cover is provided with an outlet connected to an external coalbed methane mining pipeline; the end cover, the spring assembly, the filter assembly and the oscillating plate are connected in sequence from top to bottom; the filter assembly surrounds the outlet; the oscillating plate is suspended directly above the pipe opening of the water inlet pipe; the bottom of the outer cylinder seat is provided with an outlet; the sand pump is connected with the outlet through the outlet pipe.

[0005] Furthermore, the end cover is detachably sealed and covered on the upper end of the outer cylinder seat.

[0006] Furthermore, it also includes a cleaning device for cleaning the filter assembly and the inner wall of the outer cylinder seat; the cleaning device includes a nozzle arranged circumferentially along the side wall of the outer cylinder seat; and the nozzle is provided with perforations.

[0007] Furthermore, the nozzle is provided with a water inlet chamber, an air-water mixing chamber, a throat chamber and a diffusion chamber which are connected in sequence; the water inlet chamber has a water inlet hole connected to an external water inlet pipeline at its rear end, and its front end extends into the air-water mixing chamber, and the cavity body of the extending part is a frustum with a small front and a large rear; the air-water mixing chamber has an air inlet hole connected to an external compressed air pipeline at the rear end side wall, and its front end inner cavity is a frustum with a small front and a large rear; the throat chamber is cylindrical; the diffusion chamber includes a frustum-shaped cavity with a large front and a small rear, and the perforations are opened on the inner wall of the front cavity.

[0008] Furthermore, the rear inner cavity of the diffusion tube cavity is a frustum-shaped cavity that is larger at the front and smaller at the rear, and the front inner cavity is a frustum-shaped or arc-shaped cavity that is smaller at the front and larger at the rear; a perforation is opened at the center of the top of the front inner cavity; and perforations are evenly distributed circumferentially on the side wall of the rear inner cavity close to the front inner cavity.

[0009] Furthermore, the filter screen assembly includes multiple layers of filter screens stacked in sequence from bottom to top, wherein the center of each layer of the filter screen is recessed downward to form a basin-shaped recessed portion, and the spring assembly includes multiple groups of springs connected in sequence from outside to inside to the lower surface of the end cover; each group of the springs is connected to the upper edge of a layer of the filter screen.

[0010] Furthermore, the longitudinal section of the recessed portion of each layer of the filter screen is arc-shaped or trapezoidal with a larger upper portion and a smaller lower portion.

[0011] Furthermore, the filter screen located at the upper layer is provided with a protrusion that matches with the filter hole of the filter screen located at the lower layer.

[0012] Furthermore, the upper pipe opening of the water inlet pipe is in the shape of a frustum that is small at the top and large at the bottom.

[0013] Furthermore, an annular groove is provided at the bottom of the outer cylinder seat, and the water outlet is provided at the bottom of the annular groove; the cross section of the annular groove is an arc or a trapezoid with a larger upper part and a smaller lower part.

[0014] The advantages and positive effects of the present invention are as follows: the present invention connects the end cover, spring assembly, filter assembly and oscillation plate in the inner cavity of the outer cylinder seat from top to bottom in sequence; the filter assembly surrounds the air outlet; the oscillation plate is suspended directly above the water inlet pipe orifice; the pressurized water flowing out of the water inlet pipe orifice causes the oscillation plate to swing, thereby causing the vibration of the multi-layer filter screen, and self-excited oscillation is formed under the action of the spring. The oscillation of the multi-layer filter screen can effectively prevent the filter screen from being blocked, ensuring that the coalbed methane flows out through the air outlet of the end cover and is collected. At the same time, a water outlet is provided at the bottom of the outer cylinder seat; a sand pump is used to connect to the water outlet through the water outlet pipe to pump away the coal powder and the like that is intercepted by the filter assembly and deposited at the bottom of the outer cylinder seat; in this way, the coalbed methane and the coal powder are effectively separated, and each is collected, thereby improving the extraction efficiency.

[0015] The mouth of the water inlet pipe of the present invention is a frustum-shaped pipe that is small at the top and large at the bottom, which can increase the flow rate of water when it enters the inner cavity of the outer cylinder base, facilitate triggering the oscillation plate to cause the vibration of the multi-layer filter screen, and make the vibration amplitude larger.

[0016] The filter screen assembly of the present invention comprises multiple layers of filter screens stacked in sequence from bottom to top, wherein the center of each layer of the filter screen is recessed downward to form a cone-shaped groove that is larger at the top and smaller at the bottom, thereby increasing the filter area and improving the filter efficiency.

[0017] The present invention designs the multi-layer filter screen into an upper and lower multi-layer structure. The filter screen at the upper layer is provided with a spherical protrusion, which cooperates with the filter holes of the filter screen at the lower layer and collides with each other during the oscillation process, thereby more effectively preventing the filter screen from being blocked.

[0018] The outer cylinder seat of the present invention is designed with a jet nozzle around it, and a perforation facing the filter assembly is arranged on the nozzle. The perforation is designed around the nozzle, and the coal powder on the filter is flushed by high-speed water flow, thereby extending the service life of the filter.

[0019] The bottom end of the outer cylinder seat of the present invention is an annular groove with an arc-shaped cross section, which is convenient for the washed coal powder to slide smoothly to the bottom outlet and be pumped to the ground by the sand pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the cross-sectional structure of the present invention.

[0021] Figure 2 It is a schematic diagram of the connection structure of a spring assembly, a filter assembly and an oscillating plate of the present invention;

[0022] Figure 3 It is a schematic diagram of the top view of the relative positions of the outer cylinder seat, the spring assembly, the filter assembly and the air outlet pipe of the present invention;

[0023] Figure 4It is a schematic diagram of the structure in which the protrusion of the upper filter screen matches the filter hole of the lower filter screen of the present invention;

[0024] Figure 5 It is a schematic diagram of the nozzle structure of the present invention.

[0025] In the figure: 1, water inlet pipe; 2, outer cylinder seat; 3, oscillation plate; 4, filter screen assembly; 401, filter hole; 402, spherical protrusion; 5, spring assembly; 6, air outlet pipe; 7, nozzle; 701, water inlet chamber; 702, air inlet hole; 703, air-water mixing chamber; 704, throat chamber; 705, diffusion chamber; 706, perforation; 8, water outlet; 9, water outlet pipe; 10, sand pump; 11, end cover. DETAILED DESCRIPTION

[0026] In order to further understand the content, features and effects of the present invention, the following embodiments are listed and described in detail with reference to the accompanying drawings:

[0027] See also Figures 1 to 5A self-excited oscillation filtration coal powder system for coalbed methane mining, the system comprising: an outer cylinder seat 2, an end cover 11, a spring assembly 5, a filter assembly 4, an oscillation sheet 3, a water inlet pipe 1, a water outlet pipe 9 and a sand pump 10; the outer cylinder seat 2 is a cylindrical body with a cavity inside, and a hole is opened at the center of the bottom; the upper pipe opening of the water inlet pipe 1 extends upward from the bottom opening of the outer cylinder seat 2 into the inner cavity of the outer cylinder seat 2; the lower pipe opening of the water inlet pipe 1 is connected downward to the coalbed methane mining well; the water inlet pipe 1 is sealed and connected to the bottom opening of the outer cylinder seat 2; the end cover 11 is sealed The cover is closed on the upper end of the outer cylinder seat 2; the center of the end cover 11 is provided with an air outlet connected to the external coalbed methane production pipeline; the end cover 11, the spring assembly 5, the filter assembly 4 and the oscillation plate 3 are connected in sequence from top to bottom; the spring assembly 5, the filter assembly 4 and the oscillation plate 3 are all located in the inner cavity of the outer cylinder seat 2; the filter assembly 4 surrounds the air outlet; the filter assembly 4 is used to filter the mixed fluid of coalbed methane, coal powder and water from the coalbed methane production well flowing from the water inlet pipe 1, and separate the coalbed methane from the mixture of coal powder and water. The oscillation plate 3 is suspended directly above the mouth of the water inlet pipe 1; a water outlet 8 is provided at the bottom of the outer cylinder seat 2; the sand pump 10 is connected to the water outlet 8 through the water outlet pipe 9. The end cover 11 may be provided with an outlet pipe 6 at its outlet, which is connected to an external coalbed methane production pipeline; the lower end of the outlet pipe 6 may be connected to the upper surface of the filter assembly 4. The outlet pipe 6 may be a bellows, which is an elastic product that can produce both tensile displacement and compressive deformation. The upper surface of the filter assembly 4 may be provided with an annular groove. The lower end of the outlet pipe 6 may be embedded in the annular groove of the filter assembly 4. The oscillation sheet 3 may be a plurality of arc-shaped sheets, or a plurality of cylinders or a plurality of cuboids, which may be arranged around the center of the filter assembly 4 and hung on the bottom surface of the filter assembly 4.

[0028] The water inlet pipe 1 is located at the lower part of the outer cylinder seat 2, and is connected to the coalbed methane mining well downward. The water in the coalbed methane mining well flows into the inner cavity of the outer cylinder seat 2 through the water inlet pipe 1; the water in the coalbed methane mining well flows out from the bottom to the top through the upper pipe opening of the water inlet pipe 1, and the water flows through the gap of the oscillation plate 3, causing the suspended oscillation plate 3 to vibrate, thereby driving the vibration of the filter screen assembly 4, and the coal powder washed onto the filter screen assembly 4 by the water flow falls and settles at the bottom of the outer cylinder seat 2 under the vibration of the filter screen assembly 4. The bottom of the outer cylinder seat 2 is provided with a water outlet 8, and the sand pump 10 is started to pump the groundwater together with the coal powder from the water outlet 8 at the bottom of the outer cylinder seat 2 to the ground.

[0029] The vibration of the filter assembly 4 shakes off the coal powder attached to the filter assembly 4 to prevent the coal powder from clogging the filter holes 401 of the filter assembly 4. At the same time, the coalbed methane can smoothly pass through the filter and be discharged from the gas outlet above.

[0030] Preferably, the end cover 11 may be a detachable end cover, and its lower surface or inner and outer side surfaces may be correspondingly sealed and connected with the end surface or inner and outer side surfaces of the outer cylinder seat 2. The end cover 11 is detachably sealed and covered on the upper end of the outer cylinder seat 2. The top end cover 11 and the outer cylinder seat 2 adopt a detachable sealing connection structure, which is convenient for fault inspection and replacement of internal parts.

[0031] Preferably, a cleaning device for cleaning the filter assembly and the inner wall of the outer cylinder seat may also be included; the cleaning device may include a nozzle 7 arranged along the circumference of the side wall of the outer cylinder seat 2; the nozzle 7 may be provided with a perforation 706 facing the filter assembly 4 and the inner wall of the outer cylinder seat. The jet nozzle 7 may be arranged around the outer cylinder seat 2, and pressurized water enters the nozzle 7 through a pipeline and is ejected from the perforation 706 of the nozzle 7, so that the filter and the cylinder wall can be cleaned regularly.

[0032] Preferably, the nozzle 7 may be provided with a water inlet chamber 701, an air-water mixing chamber 703, a throat chamber 704 and a diffusion chamber 705 which are interconnected in sequence; the water inlet chamber 701 may have a water inlet hole connected to an external water inlet pipeline at its rear end, and its front end may extend into the air-water mixing chamber 703, and the cavity body of the extending part of the water inlet chamber 701 may be a frustum-shaped cavity with a small front and a large rear end; the air-water mixing chamber 703 may have an air inlet hole 702 connected to an external compressed air pipeline at its rear end side wall, and its front end inner cavity may be a frustum-shaped cavity with a small front and a large rear end; the throat chamber 704 may be cylindrical; the diffusion chamber 705 may include a frustum-shaped cavity with a large front and a small rear end, and the perforation 706 may be opened on the inner wall of the front cavity of the diffusion chamber 705. The pressurized water flow is ejected from the water inlet chamber 701, and the compressed gas in the external air inlet pipe enters the air-water mixing chamber 703 from the air inlet hole 702. After the compressed air and the water flow ejected from the water inlet chamber 701 are mixed in the air-water mixing chamber 703, they are accelerated through the throat chamber 704 to form a high-speed and high-pressure water flow, which is then diffused through the diffusion chamber 705 and ejected from the perforation 706. The high-speed water flow can flush the filter screen, and the water flow reflected by the filter screen flushes the coal powder attached to the cylinder wall.

[0033] The cleaning device may include a water pump, an air pump, etc., wherein the water pump generates pressurized water and the air pump generates compressed air; the cleaning device may also directly use pressurized water and compressed air from external pipelines.

[0034] Preferably, the rear inner cavity of the diffusion tube cavity 705 may be a frustum-shaped cavity with a larger front and a smaller rear portion, and the front inner cavity may be a frustum-shaped cavity with a smaller front and a larger rear portion or an arc-shaped cavity; a perforation 706 may be opened at the center of the top of the front inner cavity; and perforations 706 may be evenly distributed along the circumferential direction on the side wall of the rear inner cavity close to the front inner cavity. The perforations 706 arranged around the axis of the nozzle 7 can increase the flushing range and improve the flushing efficiency.

[0035] Preferably, the filter assembly 4 may include multiple layers of filter screens stacked in sequence from bottom to top, wherein the center of each layer of the filter screen may be recessed downward to form a basin-shaped recessed portion, and the longitudinal section of the recessed portion of each layer of the filter screen may be an arc or a trapezoidal structure with a larger upper portion and a smaller lower portion. The longitudinal section of the recessed portion of the filter screen is preferably a trapezoidal structure with a larger upper portion and a smaller lower portion, so that the center of each layer of the filter screen may be recessed downward to form a cone-shaped recessed portion with a larger upper portion and a smaller lower portion, and the end cover 11 may be provided with an outlet pipe 6 at its outlet that is connected to an external coalbed methane production pipeline; the outlet pipe 6 may be a corrugated pipe. The lower end of the outlet pipe 6 may be connected to the upper edge of the cone-shaped recessed portion of the uppermost filter screen; the upper edge of the cone-shaped recessed portion of the uppermost filter screen may be provided with an annular groove. The lower end of the outlet pipe 6 may be embedded in the annular groove of the uppermost filter screen.

[0036] The spring assembly 5 may include multiple groups of springs sequentially connected to the lower surface of the end cover 11 from the outside to the inside; each group of the springs may be connected to the upper edge of a layer of the filter screen. The spring is a tension spring; a spring connector such as a hook or a hanging ring may be fixed to the filter screen assembly 4 and the end cover 11 respectively; and then the earrings on both sides of the spring are connected to the hook or the hanging ring.

[0037] The center of each layer of the filter screen is recessed downward to form a cone-shaped groove with a larger top and a smaller bottom, which increases the filtering area and improves the filtering efficiency. The diameter of the filter hole 401 of the filter screen located in the upper layer can be smaller than the diameter of the filter hole 401 of the filter screen located in the lower layer. The filter holes 401 of the multi-layer filter screen decrease from bottom to top, thereby filtering the coal powder step by step, achieving effective filtering of the coal powder.

[0038] Preferably, the filter screen located at the upper layer may be provided with a protrusion that matches with the filter hole 401 of the filter screen located at the lower layer. The protrusion may be a spherical protrusion 402, and the protrusion of the upper filter screen is arranged correspondingly with the filter hole 401 of the lower filter screen. During the oscillation of the filter screen, the protrusion of the upper filter screen collides with the filter hole 401 of the lower filter screen, which can clear the blocked filter hole 401, further ensuring the extraction efficiency of coalbed methane.

[0039] Preferably, the upper nozzle of the water inlet pipe 1 may be in the shape of a frustum with a small top and a large bottom. The upper nozzle of the water inlet pipe 1 may be in the shape of a frustum with a small top and a large bottom, which can increase the flow rate of water when it enters the inner cavity of the outer cylinder base, and is convenient for triggering the oscillation sheet 3 to cause the vibration of the multi-layer filter screen, so that the amplitude of the vibration is larger.

[0040] Preferably, an annular groove may be provided at the bottom of the outer cylinder seat 2, and the water outlet 8 is provided at the bottom of the annular groove. The cross section of the annular groove is an arc or a trapezoid with a larger upper part and a smaller lower part. Preferably, an annular groove with an arc cross section is provided at the bottom of the outer cylinder seat 2, so that the coal powder can be smoothly precipitated and gathered near the water outlet 8 at the bottom of the outer cylinder seat 2. The sand pump 10 starts working and pumps the groundwater together with the coal powder to the ground.

[0041] The structure and working principle of the present invention are further described below by a preferred embodiment of the present invention:

[0042] A self-excited oscillation filtration coal powder system used in the coalbed methane mining process mainly includes a frustoconical water inlet pipe 1 with a small upper part and a large lower part, an outer cylinder seat 2, an end cover 11, an oscillation plate 3, a filter screen assembly 4, a spring assembly 5, an air outlet pipe 6, a cleaning device, a water outlet pipe 9 and a sand pump 10.

[0043] The upper pipe opening of the frustum-shaped water inlet pipe 1 extends from the bottom of the outer cylinder seat 2 into the inner cavity of the outer cylinder seat 2, and is connected to the coalbed methane mining well downward. The water in the coalbed methane mining well flows through the frustum-shaped water inlet pipe 1 into the inner cavity of the outer cylinder seat 2. A detachable end cover 11 is provided on the top of the outer cylinder seat 2, and an air outlet is provided in the center of the end cover 11. An air outlet pipe 6 is sealed and connected at the air outlet. The lower end of the air outlet pipe 6 is connected to the upper surface of the filter screen assembly 4, and the air outlet pipe 6 is a corrugated pipe. A nozzle 7 is provided on the side wall of the outer cylinder seat 2, and a water outlet 8 is provided at the bottom of the outer cylinder seat 2. The filter screen assembly 4 is arranged in the internal cavity of the outer cylinder seat 2, and the filter screen assembly 4 is located. The lower end of the filter screen assembly 4 is connected to the oscillation plate 3, and the upper end of the filter screen assembly 4 is connected to the spring assembly 5, and is fixed under the end cover 11 through the spring assembly 5.

[0044] The water inlet pipe 1 is a frustum-shaped pipe that is small at the top and large at the bottom, and the oscillating plate 3 is suspended directly above the water outlet 8 of the frustum-shaped water inlet pipe 1. According to the principle of liquid flow continuity, the water flow in the coalbed methane mining well flows from bottom to top, and the flow velocity is the largest when it flows through the top water outlet 8 of the frustum-shaped water inlet pipe 1. The high-speed water flow passes through the gap of the oscillating plate 3, realizing the high-frequency oscillation of the oscillating plate 3, thereby driving the high-frequency vibration of the filter mesh assembly 4, preventing the coal powder in the water flow from clogging the filter holes 401 of the filter mesh assembly 4. While filtering the coal powder, the coalbed methane can also smoothly pass through the filter mesh assembly 4 and be discharged from the air outlet above.

[0045] The end cover 11 is detachable, which is convenient for fault inspection and replacement of internal parts. The bottom of the outer cylinder seat 2 is provided with an annular groove with an arc cross section, and the bottom of the annular groove is provided with a water outlet 8, which facilitates the smooth sedimentation and accumulation of coal powder near the water outlet 8 at the bottom of the annular groove, and facilitates the sand pump 10 to pump the coal powder to the ground.

[0046] The filter assembly 4 is composed of multiple layers of filter screens stacked from bottom to top, and the center of each layer of filter screen is a cone-shaped groove that is larger at the top and smaller at the bottom. The diameter of the filter holes 401 of the multiple layers of filter screens also decreases from bottom to top, that is, the diameter of the filter holes 401 of the filter screen located on the upper layer is smaller than the diameter of the filter holes 401 of the filter screen located on the lower layer, thereby filtering the coal powder step by step to achieve effective filtering of the coal powder. The multiple layers of filter screens are provided with spherical protrusions 402, and the spherical protrusions 402 of the upper filter screen are arranged to correspond to the filter holes 401 of the lower filter screen. During the oscillation process, the spherical protrusions 402 collide with the filter holes 401, which can clear the blocked filter holes 401, further improving the extraction efficiency of coalbed methane.

[0047] The system also includes a cleaning device for cleaning the filter assembly and the inner wall of the outer cylinder seat; the cleaning device includes a nozzle 7 arranged along the circumference of the side wall of the outer cylinder seat 2; the nozzle 7 is provided with a perforation 706 facing the filter assembly 4. The jet nozzle 7 is arranged around the outer cylinder seat 2, and pressurized water enters the nozzle 7 through a pipeline and is ejected from the perforation 706 of the nozzle 7, which can regularly clean the filter and the cylinder wall and extend the service life of the system.

[0048] The nozzle 7 is provided with a water inlet chamber 701, an air-water mixing chamber 703, a throat chamber 704 and a diffusion chamber 705 which are connected in sequence; the water inlet chamber 701 has a water inlet hole connected to an external water inlet pipeline at its rear end, and its front end extends into the air-water mixing chamber 703, and the cavity body of the extended part is a cone-shaped cavity with a small front and a large rear; the air-water mixing chamber 703 has an air inlet hole 702 connected to an external compressed air pipeline at the rear end side wall, and its front end inner cavity is a cone-shaped cavity with a small front and a large rear; the throat chamber 704 is cylindrical; the diffusion chamber 705 includes a cone-shaped cavity with a large front and a small rear, and the perforation 706 is opened on the inner wall of the front cavity. The pressurized water jets out from the water inlet chamber 701, mixes with the air in the air inlet pipe in the air-water mixing chamber 703, and then accelerates through the throat pipe to form a high-speed high-pressure water flow, which then diffuses through the diffuser and then jets out from the perforations 706. The high-speed water flow can flush the filter screen, and part of the water flow reflected by the filter screen flushes the coal powder attached to the cylinder wall. At least part of the perforations 706 are arranged around the axis of the nozzle 7 to increase the flushing range and improve the flushing efficiency.

[0049] The embodiments described above are only used to illustrate the technical ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The patent scope of the present invention cannot be limited only by this embodiment, that is, any equivalent changes or modifications made to the spirit disclosed by the present invention still fall within the patent scope of the present invention.

Claims

1. A self-excited oscillation filtration coal powder system used in coalbed methane mining, characterized in that: include: Outer cylinder seat, end cover, spring assembly, filter assembly, oscillating plate, water inlet pipe, water outlet pipe and sand pump; The outer cylinder seat is a cylindrical body with a cavity inside, and a hole is opened at the center of its bottom; the upper pipe opening of the water inlet pipe extends upward from the hole at the bottom of the outer cylinder seat into the inner cavity of the outer cylinder seat; the lower pipe opening of the water inlet pipe is downwardly connected to the coalbed methane production well; the end cover sealing cover is closed on the upper end of the outer cylinder seat; the center of the end cover is provided with an outlet connected to the external coalbed methane production pipeline; the end cover, the spring assembly, the filter assembly and the oscillation plate are connected in sequence from top to bottom; the filter assembly surrounds the outlet; the oscillation plate is suspended just above the pipe opening of the water inlet pipe; a water outlet is provided at the bottom of the outer cylinder seat; the sand pump is connected to the water outlet through the water outlet pipe; The upper pipe opening of the water inlet pipe is in the shape of a frustum that is small at the top and large at the bottom; An annular groove is provided at the bottom of the outer cylinder seat, and the water outlet is provided at the bottom of the annular groove; the cross section of the annular groove is an arc or a trapezoid with a larger upper portion and a smaller lower portion.

2. The self-excited oscillation pulverized coal filtering system for coalbed methane mining according to claim 1, characterized in that: The end cover is detachably and sealingly covered on the upper end of the outer cylinder seat.

3. The self-excited oscillation pulverized coal filtering system for coalbed methane mining according to claim 1, characterized in that: It also includes a cleaning device for cleaning the filter assembly and the inner wall of the outer cylinder seat; the cleaning device includes a nozzle arranged circumferentially along the side wall of the outer cylinder seat; and the nozzle is provided with perforations.

4. The self-excited oscillation pulverized coal filtering system for coalbed methane mining according to claim 3, characterized in that: The nozzle is provided with a water inlet chamber, an air-water mixing chamber, a throat chamber and a diffusion chamber which are connected in sequence; the water inlet chamber has a water inlet hole connected to an external water inlet pipeline at its rear end, and its front end extends into the air-water mixing chamber, and the cavity body of the extending part is a frustum with a small front and a large rear; the air-water mixing chamber has an air inlet hole connected to an external compressed air pipeline at the rear end side wall, and its front end inner cavity is a frustum with a small front and a large rear; the throat chamber is cylindrical; the diffusion chamber includes a frustum-shaped cavity with a large front and a small rear, and the perforations are opened on the inner wall of the front cavity.

5. The self-excited oscillation pulverized coal filtering system for coalbed methane mining according to claim 4, characterized in that: The diffusion tube cavity has a rear inner cavity in the shape of a cone that is larger at the front and smaller at the back, and a front inner cavity in the shape of a cone that is smaller at the front and larger at the back or an arc; A perforation is provided at the center of the top of the front inner cavity; and perforations are evenly distributed along the circumferential direction on the side wall of the rear inner cavity close to the front inner cavity.

6. The self-excited oscillation pulverized coal filtering system used in coalbed methane mining according to claim 1, characterized in that: The filter screen assembly includes multiple layers of filter screens stacked in sequence from bottom to top, wherein the center of each layer of the filter screen is recessed downward to form a basin-shaped recessed portion, and the spring assembly includes multiple groups of springs connected in sequence from outside to inside to the lower surface of the end cover; each group of the springs is connected to the upper edge of a layer of the filter screen.

7. The self-excited oscillation pulverized coal filtering system used in the coalbed methane mining process according to claim 6, characterized in that: The longitudinal section of the recessed portion of each layer of the filter screen is an arc or a trapezoid with a larger top and a smaller bottom.

8. The self-excited oscillation pulverized coal filtering system for coalbed methane mining according to claim 6, characterized in that: The filter screen located at the upper layer is provided with a protrusion which matches with the filter hole of the filter screen located at the lower layer.

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