Underground gasifier process water circulation device for underground coal gasification process

Abstract

The utility model relates to a process water circulation device of an underground gasification furnace for an underground coal gasification process. The circulating device comprises a coarse filter, a reservoir, a water injection pump and a valve which are arranged on the ground, the coarse filter, the reservoir, the water injection pump and the valve are sequentially connected through a ground water injection pipe, an injection well and a condensate channel are formed in the ground, the opening end of the injection well is a well opening, and the other end of the injection well extends to a coal seam. An underground gasification furnace is arranged below the coal seam and used for igniting coal, and a condensation pipeline is arranged in the condensate channel; according to the circulating device, condensate is conveyed into the coarse filter through the condensate channel, the condensate is filtered by the coarse filter, the filtered condensate is sprayed to a high-temperature combustion area of the underground gasification furnace through the nozzle, and synthesis gas is cooled. And the generation of sewage can be reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of underground coal gasification, and in particular relates to an underground gasification furnace process water circulation device used in the underground coal gasification process. Background Art

[0002] Underground coal gasification (ISC) is a process that converts coal directly into product gas, usually called synthesis gas, by combustion and gasification of underground coal seams in the presence of an oxidant. The synthesis gas can then be used as a feedstock for a variety of applications, including fuel production, chemical production, and power generation. This underground coal gasification technology is applicable to most coal deposits. In view of the increasingly stringent environmental requirements for the mining industry and considering the related labor and infrastructure costs, this technology is undoubtedly very attractive.

[0003] Surface wells penetrate the coal seam directly, providing an effective channel for oxidant injection and product gas production. A pair of wells are connected or extended horizontally underground to form a substantially horizontal drilling channel (also referred to as a coal seam well or connecting channel). This channel facilitates oxidant injection, combustion zone growth and product gas transportation. A well used for oxidant injection is called an "injection well" and the other well used for producing product gas is called a "product well". Both directional horizontal drilling and vertical drilling can be used as injection wells or product wells. Underground coal gasification (ISC) may also require the use of one or more vertical wells (e.g., functional wells and auxiliary wells) between the injection well and the product well.

[0004] When there are injection wells, product wells and horizontal channels connecting the two in a coal seam, this structure is called an underground coal gasification (ISC) unit or well pair. The ISC unit includes a combustion zone, a gasification zone and a pyrolysis zone, wherein the combustion zone is near the oxidant injection point in the coal seam; the gasification zone is radially surrounding the combustion zone or downstream of the combustion zone, where the coal is gasified and partially oxidized to generate product gas; the pyrolysis zone is downstream of the gasification zone, where the pyrolysis reaction of coal generally occurs. The high-temperature product gas flows downstream from the gasification zone and is eventually transported to the ground from the wellhead of the product well. While the coal is burning or gasifying, the ISC combustion zone in the coal seam will grow and become larger.

[0005] The product gas (raw synthesis gas) generated by underground coal gasification usually contains synthesis gas (a mixture of CO, CO2, H2, CH4 and other gases) and other components such as solid particles, water, coal tar, hydrocarbon vapor, and other trace components including H2S, NH4, COS, etc.). The complexity of its composition depends on many aspects: the oxidant used in underground coal gasification (air or other oxidants, such as oxygen, oxygen-enriched air or steam mixture), the intrinsic water in the coal seam or the water infiltrating into the coal seam from the surrounding strata, the coal quality and the operating parameters of the underground coal gasification process, including temperature, pressure, etc.

[0006] The current problems faced by underground coal gasification technology are: the temperature of the synthesis gas produced by the underground gasification furnace is as high as 600℃~800℃. The high-temperature synthesis gas is damaged when passing through the wellbore of the product well due to the high temperature, causing the casing, oil pipe and cementing cement of the wellbore to be damaged by thermal stress, and the casing connector and cementing cement ring are damaged. In addition, sewage will be generated after the synthesis gas is cooled, and the sewage needs to be treated during operation, which greatly reduces the work efficiency. Utility Model Content

[0007] The purpose of the utility model is to provide a circulation device with simple structure and reasonable design in order to solve the above problems.

[0008] The utility model achieves the above-mentioned purpose through the following technical solutions:

[0009] The utility model provides an underground gasification furnace process water circulation device for underground coal gasification process, comprising a coarse filter, a water reservoir, a water injection pump and a valve arranged on the ground, wherein the coarse filter, the water reservoir, the water injection pump and the valve are sequentially connected through a ground water injection pipe, an injection well and a condensate channel are opened on the ground, the opening end of the injection well is a wellhead, the other end of the injection well extends to the coal seam, an underground gasification furnace is arranged below the coal seam for igniting coal, a condensation pipeline is arranged in the condensate channel, one end of the condensation pipeline is connected to the coarse filter, and the other end is connected to the underground gasification furnace for collecting and transports condensate generated by coal combustion. The inner wall of the injection well close to the ground is connected with a surface casing, the other end of the surface casing extends underground, the inner sleeve of the surface casing is connected with a production casing, an oil pipe and a water injection coiled pipe are arranged in the production casing, the ends of the production casing, the oil pipe and the water injection coiled pipe away from the ground are all extended to the high-temperature combustion zone of the underground gasifier, the other end of the water injection coiled pipe is connected to the wellhead of the injection well, and is connected to the output end of the valve through a wellhead bypass, the other end of the oil pipe extends to the wellhead of the injection well, and the end of the water injection coiled pipe away from the ground is connected with a nozzle.

[0010] As a further optimization scheme of the utility model, the coarse filter includes a box body, the upper surface of the box body is provided with a liquid inlet, the upper surface of the box body is connected to a rotating motor, the driving end of the rotating motor extends to the interior of the box body and is fixedly connected to a rotating column, the surface of the rotating column is connected to at least multiple groups of rotating plates, the multiple groups of rotating plates are distributed in a circle, and filter cavities are formed between every two groups of rotating plates and the inner wall of the box body, and a filter assembly is provided in each group of filter cavities, the filter assembly includes a filter element, the rotating motor drives the multiple groups of filter elements to rotate and replace each other, and a liquid outlet is provided on the surface of the box body near the bottom.

[0011] As a further optimization scheme of the utility model, the filter assembly also includes a sleeve frame, which is detachably connected to the surface of the rotating column, a certain space is reserved between the upper end of the sleeve frame and the top of the box body, and the filter element is detachably connected to the inner wall of the sleeve frame.

[0012] As a further optimization solution of the utility model, the filter element includes a lap portion and a main body portion, the inner wall of the sleeve frame protrudes toward the middle to form a lap plate, and the lap portion is lapped on the upper surface of the lap plate.

[0013] As a further optimization scheme of the present utility model, the surface of the sleeve frame close to the rotating column side is connected with an insert block, the cross-section of the insert block is "T"-shaped, the side of the rotating column is provided with an installation groove, the inner wall of the installation groove is slidably connected with two groups of symmetrically arranged blocks, the surface of each group of blocks is connected with spring 1, the other end of spring 1 is fixedly connected to the inner wall of the installation groove, the inner wall of the installation groove is slidably connected with a trigger block, the surface of the trigger block is connected with spring 2, the other end of spring 2 is fixedly connected to the inner wall of the installation groove, the surface of the block is connected with a matching block, the surface of the trigger block is connected with a lifting block, and the surfaces where the lifting block and the matching block contact each other are both inclined surfaces.

[0014] As a further optimization solution of the utility model, a door is hinged on the side of the box body, and the filter assembly can be taken out from the door.

[0015] As a further optimization solution of the utility model, a material dropping channel is provided on the bottom surface of the main body, and a door structure is connected to the channel.

[0016] As a further optimization scheme of the utility model, the inner bottom of the box body is connected to a base, the rotating column is rotatably connected to the surface of the base, and two groups of partitions are connected to the sides of the base. The two groups of partitions cooperate with the base to separate the space at the bottom of the box body into a liquid flow chamber and a particle collection chamber. The particle collection chamber corresponds to the box door, and the inner bottom of the particle collection chamber is connected to a collection box.

[0017] As a further optimization solution of the utility model, the liquid outlet is communicated with the liquid flow cavity.

[0018] The beneficial effect of the utility model is that the utility model transports the condensate to the coarse filter through the condensate channel, the coarse filter filters the condensate, and the filtered condensate is sprayed to the high-temperature combustion zone of the underground gasification furnace through the nozzle to cool the synthesis gas. Through this circulation device, not only the synthesis gas can be cooled, but also the generation of sewage can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the overall structure diagram of Embodiment 1 of the present utility model;

[0020] Figure 2 This is a schematic diagram of the internal structure of the coarse filter of Example 2 of the utility model;

[0021] Figure 3 This is a top view of the internal structure of the coarse filter of Example 2 of the utility model;

[0022] Figure 4 This is a schematic diagram of the internal structure of the frame of Embodiment 2 of the present utility model;

[0023] Figure 5 This is a schematic diagram of the partition structure of Example 2 of the utility model;

[0024] Figure 6 This is a schematic diagram of the installation slot structure of Embodiment 2 of the utility model;

[0025] Figure 7 This is a schematic diagram of the positions of the matching block and the lifting block in Example 2 of the utility model (partial enlarged view);

[0026] Figure 8 This is a schematic diagram of the internal structure of the installation slot of Embodiment 2 of the present utility model;

[0027] Fig. 9 This is a schematic diagram of the positions of the spring 2 and the trigger block in Embodiment 2 of the utility model.

[0028] In the figure: 1, underground gasifier; 2, nozzle; 3, water injection coiled pipe; 4, production casing; 5, surface casing; 6, injection well; 7, valve; 8, water injection pump; 9, water reservoir; 10, coarse filter; 11, condensate channel; 12, coal seam; 13, oil pipe; 14, box; 15, rotating motor; 16, rotating column; 17, rotating plate; 18, filter chamber; 19, filter element; 191, overlap; 192. Main body; 20. Liquid inlet; 21. Liquid outlet; 22. Frame; 221. Strap; 23. Insert block; 24. Mounting slot; 25. Block; 26. Spring 1; 27. Trigger block; 28. Spring 2; 29. ​​Matching block; 30. Lifting block; 31. Box door; 32. Door structure; 33. Base; 34. Partition; 35. Liquid flow chamber; 36. Particle collection chamber; 37. Collection box. DETAILED DESCRIPTION

[0029] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0030] Example 1

[0031] like Figure 1As shown, an underground gasifier process water circulation device for underground coal gasification process includes a coarse filter 10, a water reservoir 9, a water injection pump 8 and a valve 7 arranged on the ground. The coarse filter 10, the water reservoir 9, the water injection pump 8 and the valve 7 are connected in sequence through a ground water injection pipe. An injection well 6 and a condensate channel 11 are opened on the ground. The opening end of the injection well 6 is a wellhead, and the other end of the injection well 6 extends to a coal seam 12. An underground gasifier 1 is arranged below the coal seam 12 for igniting coal. A condensation pipe is arranged in the condensate channel 11. One end of the condensation pipe is connected to the coarse filter 10, and the other end is connected to the underground gasifier 1 for collecting The condensate produced by coal combustion is transported. The inner wall of the injection well 6 close to the ground is connected with a surface casing 5. The other end of the surface casing 5 extends underground. The inner sleeve of the surface casing 5 is connected with a production casing 4. The production casing 4 is provided with an oil pipe 13 and a water injection coiled pipe 3. The ends of the production casing 4, the oil pipe 13 and the water injection coiled pipe 3 away from the ground are all extended to the high-temperature combustion zone of the underground gasifier 1. The other end of the water injection coiled pipe 3 is connected to the wellhead of the injection well 6, and is connected to the output end of the valve 7 through a wellhead bypass. The other end of the oil pipe 13 extends to the wellhead of the injection well 6. The end of the water injection coiled pipe 3 away from the ground is connected with a nozzle 2.

[0032] It should be noted that the water injection coiled pipe 3, oil pipe 13, injection well 6, water injection pump 8 and water reservoir 9, coarse filter 10, valve 7, condensate channel 11, and ground water injection pipe constitute a condensate circulation system and become an integral part of the condensate circulation system channel.

[0033] Furthermore, cement slurry material (cementing cement) is injected between the surface casing 5 and the production casing 4 and the inner wall of the injection well 6 to form a cementing cement ring.

[0034] In this embodiment, the following components are further described:

[0035] The water injection coiled pipe 3 is bundled outside the oil pipe 13. The water injection coiled pipe 3 is made of PVC polyvinyl chloride pipe / HDPE high molecular polyethylene pipe. The inner diameter of the water injection coiled pipe 3 meets the requirements of the condensate flow rate, and its outer diameter is 1 / 2-2 inches;

[0036] The surface casing 5 and the production casing 4 are made of materials that can meet the requirements of formation collapse on the casing, and can be made of carbon steel. The sizes of the two are 95 / 8 inches to 133 / 8 inches, and the connection is made of airtight buckles;

[0037] The oil pipe 13 is used to inject the oxidant. Its material can meet the corrosion requirements of oxygen and air, and can be made of carbon steel. The inner diameter of the pipe can reach the size required for the air and oxygen delivery, specifically, it can be 5-95 / 8 inches;

[0038] Cementing cement ring, the cementing cement performance decline period meets the product well service life, and there is no leakage of gas in the gasifier wellbore;

[0039] The injection well 6 is used to connect the surface casing 5 and the production casing 4. The oil pipe 13 is suspended inside the injection well 6. The water injection coiled pipe 3 is connected to the injection well and connected through the output end of the valve 7 next to the wellhead to form a condensate transportation channel.

[0040] The valve 7 is arranged between the injection well 6 and the water injection pump 8. The model and type can be selected according to the production process requirements of the gasifier. It is used to adjust the condensate flow rate and can close the condensate delivery channel in time when an abnormal situation occurs.

[0041] Water injection pump 8, the water injection pump 8 provides power for the condensate, the lift of the water injection pump 8 needs to meet the requirements of the jet of the condensate nozzle 2, and the displacement of the water injection pump 8 meets the production requirements of the underground gasifier 1;

[0042] The water reservoir 9 provides a storage place for the condensate and has the function of cooling the condensate to reduce the temperature of the condensate to a normal temperature without damaging the seals of the water injection pump 8 and other equipment due to the temperature;

[0043] The coarse filter 10 is used to remove dust and other particles from the gasifier condensate. The gasifier process condensate generated from the underground gasifier is transported to the coarse filter 10 through a condensation pipeline.

[0044] It needs further explanation:

[0045] 1) Before using the underground gasifier process water circulation system, it is necessary to simulate the gasification process of the underground gasifier in advance to obtain process parameters such as synthesis gas pressure, composition, output, temperature, etc.

[0046] 2) After obtaining the gasification simulation parameters, the pipe string dimensions of the surface casing 5, production casing 4, and oil pipe 13 of the underground gasifier injection well are designed according to the process parameters such as synthesis gas pressure and output;

[0047] 3) Determine the processing capacity and performance requirements of the rough processor according to the amount of condensate produced by the underground gasifier process in the design, and the fine particulate matter discharged by the rough processor needs to meet the environmental emission standards;

[0048] 4) The ground water reservoir provides a storage place for the condensate. The capacity of the water reservoir must meet the discharge volume of the condensate from the underground gasification process and have the function of cooling the condensate. The temperature of the condensate entering the injection pump cannot exceed the bearing capacity of the injection pump and other ground equipment;

[0049] 5) The injection pump performance meets the production requirements of the underground gasifier, and the displacement meets the demand for condensate to participate in the gasifier reaction;

[0050] 6) The size and specifications of the water injection coiled pipe 3 are selected according to the amount of condensate required to meet the underground gasifier reaction. After the size and specifications of the water injection coiled pipe 3 are determined, the injection distance of the condensate is calculated according to the process production requirements of the underground gasifier, and the size of the nozzle 2 installed at the front end of the water injection coiled pipe 3 (the end away from the ground) is selected.

[0051] In actual use, the underground gasifier 1 injects oxidant and underground gasification process condensate to controllably burn the coal seam 12 to produce high-temperature synthesis gas, and transports the synthesis gas to the ground through the product well channel. The condensate is transported to the coarse filter 10 through the condensate channel 11, and the coarse filter 10 filters the condensate. The filtered condensate then passes through the water reservoir 9, the water injection pump 8 and the valve 7 in turn, enters the water injection continuous pipe 3 from the wellhead of the injection well 6, and is finally sprayed from the nozzle 2 to the high-temperature combustion zone of the underground gasifier 1 to cool the synthesis gas. The above steps are repeated. Through this circulation system, not only the synthesis gas can be cooled, but also the generation of sewage can be reduced.

[0052] Example 2

[0053] This embodiment provides a coarse filter for the underground gasifier process water circulation device provided in Example 1, such as Figures 2 to 3 As shown, it includes a box body 14, the upper surface of the box body 14 is provided with a liquid inlet 20, the upper surface of the box body 14 is connected to a rotating motor 15, the driving end of the rotating motor 15 extends to the inside of the box body 14, and is fixedly connected to a rotating column 16, the surface of the rotating column 16 is connected to at least a plurality of rotating plates 17, the plurality of rotating plates 17 are distributed in a circle, and a filter cavity 18 is formed between every two groups of rotating plates 17 and the inner wall of the box body 14, and a filter assembly is arranged in each group of filter cavities 18, and the filter assembly includes a filter element 19, and the rotating motor 15 drives the plurality of filter elements 19 to rotate for mutual replacement, and a liquid outlet 21 is arranged on the surface of the box body 14 near the bottom.

[0054] In this embodiment, the coarse filter in this embodiment is described by taking the arrangement of three groups of filter chambers 18 as an example.

[0055] It should be noted that the liquid inlet 20 is connected to the condensation pipe, and the liquid outlet 21 is connected to the water reservoir 9 through a ground water injection pipe. The condensation pipe transports the condensate to the box 14, and the condensate is filtered by the filter element 19. The filtered condensate flows out from the liquid outlet 21 and is transported to the water reservoir 9 by the ground water injection pipe connected to the liquid outlet 21.

[0056] In actual use, the filter element 19 located below the liquid inlet 20 is the first filter element 19, the filter element 19 corresponding to the chamber door 31 is the second filter element 19, and the remaining group of filter elements 19 is the third filter element 19. When a large amount of solid particles are accumulated in the first filter element 19, the rotating motor 15 can be started to rotate the second filter element 19 to the bottom of the liquid inlet 20, and the first filter element 19 can be replaced. The first filter element 19 is moved to the position of the second filter element 19. At this time, the second filter element 19 can continue to filter the condensate.

[0057] Furthermore, the filter assembly also includes a sleeve frame 22, which is detachably connected to the surface of the rotating column 16, with a certain space reserved between the upper end of the sleeve frame 22 and the top of the box body 14, and the filter element 19 is detachably connected to the inner wall of the sleeve frame 22.

[0058] Furthermore, the filter element 19 includes a lap portion 191 and a main body portion 192 . The inner wall of the sleeve frame 22 protrudes toward the middle to form a lap plate 221 . The lap portion 191 is lapped on the upper surface of the lap plate 221 .

[0059] like Figures 6 to 9 As shown, the surface of the sleeve 22 close to the rotating column 16 is connected with an insert block 23, the cross-section of the insert block 23 is "T"-shaped, and a mounting groove 24 is opened on the side of the rotating column 16. The inner wall of the mounting groove 24 is slidably connected with two groups of symmetrically arranged blocks 25, and the surface of each group of blocks 25 is connected with a spring 1 26, and the other end of the spring 1 26 is fixedly connected to the inner wall of the mounting groove 24. The inner wall of the mounting groove 24 is slidably connected with a trigger block 27, and the surface of the trigger block 27 is connected with a spring 28, and the other end of the spring 28 is fixedly connected to the inner wall of the mounting groove 24. The surface of the block 25 is connected with a matching block 29, and the surface of the trigger block 27 is connected with a lifting block 30, and the surfaces where the lifting block 30 and the matching block 29 contact each other are both inclined surfaces.

[0060] like Figures 2 to 5 As shown, a door 31 is hinged on the side of the box body 14 , and the filter assembly can be taken out from the door 31 .

[0061] In actual use, when the filter element 19 needs to be replaced, the box door 31 is first opened, and the bottom of the sleeve frame 22 is held and lifted upward. At this time, the plug block 23 presses the trigger block 27 and drives the trigger block 27 to move upward, and the trigger block 27 drives the lifting block 30 to move upward. Due to the mutual cooperation between the lifting block 30 and the matching block 29, the two sets of card blocks 25 are away from the plug block 23. At this time, the sleeve frame 22 can be moved toward the box door 31, so that the sleeve frame 22 can be disassembled, and then taken out from the top of the sleeve frame 22 The filter element 19 can be replaced. When installing the sleeve frame 22, the plug block 23 can be directly inserted into the installation groove 24. Specifically, before the plug block 23 is fully inserted into the installation groove 24, the plug block 23 first contacts the clamping block 25, and the contact surface between the clamping block 25 and the plug block 23 is an inclined surface. At this time, the plug block 23 drives the two groups of clamping blocks 25 to move away from the plug block 23. When the plug block 23 is fully inserted into the installation groove 24, the clamping block 25 clamps the two sides of the plug block 23 to fix it.

[0062] It should be noted that the sleeve frame 22 can be replaced manually or by a robot.

[0063] Furthermore, a material dropping channel is provided on the bottom surface of the main body 192, and a door structure 32 is connected to the channel.

[0064] It should be noted that, in this embodiment, the door structure 32 is an electrically controlled valve.

[0065] Furthermore, the inner bottom of the box body 14 is connected to a base 33, the rotating column 16 is rotatably connected to the surface of the base 33, and the sides of the base 33 are connected to two groups of partitions 34. The two groups of partitions 34 cooperate with the base 33 to separate the space at the bottom of the box body 14 into a liquid flow chamber 35 and a particle collection chamber 36. The particle collection chamber 36 corresponds to the box door 31, and the inner bottom of the particle collection chamber 36 is connected to a collection box 37.

[0066] Furthermore, the liquid outlet 21 is communicated with the liquid flow cavity 35 .

[0067] In actual use, the liquid flow cavity 35 is located below the first filter element 19. When a large amount of solid particles are accumulated in the first filter element 19 and it is moved to the position of the third filter element 19, the first filter element 19 is still located in the liquid flow cavity 35. At this time, the residual liquid in the first filter element 19 will drip into the liquid flow cavity 35. When the third filter element 19 moves to the bottom of the liquid inlet 20 and the first filter element 19 needs to be replaced, the removed filter element 19 will not be stained with a large amount of liquid. Through this arrangement, the filtered condensate can be fully utilized.

[0068] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the utility model. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model.

Claims

1. A process water circulation device for an underground gasifier used in an underground coal gasification process, characterized in that: The invention comprises a coarse filter (10), a water reservoir (9), a water injection pump (8) and a valve (7) arranged on the ground. The coarse filter (10), the water reservoir (9), the water injection pump (8) and the valve (7) are connected in sequence through a ground water injection pipe. An injection well (6) and a condensate channel (11) are provided on the ground. The opening end of the injection well (6) is a wellhead. The other end of the injection well (6) extends to a coal seam (12). An underground gasification furnace (1) is provided below the coal seam (12) for igniting coal. A condensation pipe is provided in the condensate channel (11). One end of the condensation pipe is connected to the coarse filter (10) and the other end is connected to the underground gasification furnace (1). The condensate is used to collect and transport condensate generated by coal combustion. The inner wall of the injection well (6) at one end close to the ground is connected to a surface casing (5), the other end of the surface casing (5) extends underground, the inner sleeve of the surface casing (5) is connected to a production casing (4), an oil pipe (13) and a water injection coiled pipe (3) are arranged in the production casing (4), the ends of the production casing (4), the oil pipe (13) and the water injection coiled pipe (3) away from the ground all extend to the high-temperature combustion zone of the underground gasifier (1), the other end of the water injection coiled pipe (3) is connected to the wellhead of the injection well (6), and is connected to the output end of the valve (7) through a wellhead bypass, the other end of the oil pipe (13) extends to the wellhead of the injection well (6), and the end of the water injection coiled pipe (3) away from the ground is connected to a nozzle (2).

2. The process water circulation device for underground gasification furnace used in underground coal gasification process according to claim 1, characterized in that: The coarse filter (10) comprises a casing (14), the upper surface of which is provided with a liquid inlet (20), the upper surface of which is connected with a rotating motor (15), the driving end of which extends into the interior of the casing (14) and is fixedly connected with a rotating column (16), the surface of which is connected with at least a plurality of rotating plates (17), the plurality of rotating plates (17) being distributed in a circular pattern, a filter cavity (18) being formed between every two groups of rotating plates (17) and the inner wall of the casing (14), a filter assembly being provided in each group of filter cavities (18), the filter assembly comprising a filter element (19), the rotating motor (15) driving the plurality of filter elements (19) to rotate and replace each other, and a liquid outlet (21) being provided on the surface of the casing (14) near the bottom.

3. The process water circulation device for an underground gasifier used in an underground coal gasification process according to claim 2, characterized in that: The filter assembly further comprises a sleeve frame (22), wherein the sleeve frame (22) is detachably connected to the surface of the rotating column (16), a space is reserved between the upper end of the sleeve frame (22) and the top of the housing (14), and the filter element (19) is detachably connected to the inner wall of the sleeve frame (22).

4. The process water circulation device for an underground gasifier used in an underground coal gasification process according to claim 3, characterized in that: The filter element (19) comprises a lap joint portion (191) and a main body portion (192); the inner wall of the sleeve frame (22) protrudes toward the middle to form a lap plate (221); and the lap joint portion (191) is lapped on the upper surface of the lap plate (221).

5. The process water circulation device for underground gasification furnace used in underground coal gasification process according to claim 3, characterized in that: The surface of the sleeve frame (22) close to the rotating column (16) is connected with an insert block (23), the cross section of the insert block (23) is in a "T" shape, the side of the rotating column (16) is provided with a mounting groove (24), the inner wall of the mounting groove (24) is slidably connected with two groups of symmetrically arranged clamping blocks (25), the surface of each group of clamping blocks (25) is connected with a spring 1 (26), the other end of the spring 1 (26) is fixedly connected to the inner wall of the mounting groove (24), the inner wall of the mounting groove (24) is slidably connected with a trigger block (27), the surface of the trigger block (27) is connected with a spring 2 (28), the other end of the spring 2 (28) is fixedly connected to the inner wall of the mounting groove (24), the surface of the clamping block (25) is connected with a matching block (29), the surface of the trigger block (27) is connected with a lifting block (30), and the surfaces of the lifting block (30) and the matching block (29) that contact each other are both inclined surfaces.

6. The process water circulation device for underground gasification furnace used in underground coal gasification process according to claim 2, characterized in that: A door (31) is hingedly connected to the side of the box body (14), and the filter assembly can be taken out from the door (31).

7. The process water circulation device for underground gasification furnace used in underground coal gasification process according to claim 4, characterized in that: The bottom surface of the main body (192) is provided with a material dropping channel, and a door structure (32) is connected to the channel.

8. The process water circulation device for underground gasification furnace used in underground coal gasification process according to claim 2, characterized in that: The inner bottom of the box body (14) is connected to a base (33); the rotating column (16) is rotatably connected to the surface of the base (33); the side of the base (33) is connected to two groups of partitions (34); the two groups of partitions (34) cooperate with the base (33) to separate the space at the inner bottom of the box body (14) into a liquid flow chamber (35) and a particle collection chamber (36); the particle collection chamber (36) corresponds to the box door (31); and the inner bottom of the particle collection chamber (36) is connected to a collection box (37).

9. The process water circulation device for underground gasification furnace used in underground coal gasification process according to claim 8, characterized in that: The liquid outlet (21) is in communication with the liquid flow chamber (35).

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