An underground coal gasification drilling mining process

Abstract

An underground coal gasification drilling mining process specifically includes the following steps: (1) at a pre-set construction site, operating a new underground coal gasification mining system to drill vertically into the stratum in a vertical direction, crushing the stratum into soil residue and discharging it to the ground, thereby forming a vertical borehole; (2) when the new underground coal gasification mining system drills downward into the coal seam, changing the drilling direction so that the new underground coal gasification mining system drills in a certain horizontal direction within the coal seam, crushing the coal seam into coal powder; (3) the crushed coal powder is burned and gasified in the new underground coal gasification mining system, and the synthesis gas generated after the combustion is transported to a gas gathering station on the ground for further processing. The present invention can realize the transformation from vertical drilling into the stratum to horizontal drilling into the coal seam, crushing the coal seam into coal powder, and burning and gasifying the coal powder, thereby realizing the integrated operation of coal seam drilling and gasification.

Description

Technical Field

[0001] The present invention relates to the technical field of underground coal gasification, in particular to an underground coal gasification drilling mining process. Background Art

[0002] Underground coal gasification, also known as underground coal gasification, is the process of controlled combustion of underground coal to produce combustible gas through thermal and chemical reactions on the coal. It is a new multidisciplinary technology for the development of clean energy and chemical raw materials that integrates well construction, coal mining, and gasification processes. Its essence is to only extract the energy-containing components in coal, changing physical coal mining to chemical coal mining. Therefore, it has the advantages of good safety, low investment, high efficiency, and low pollution, and is known as the second-generation coal mining method.

[0003] However, there are relatively few related underground coal gasification mining processes in China, and the technology is still not very mature. Summary of the Invention

[0004] The purpose of the present invention is to provide an underground coal gasification drilling mining process, which can realize the transformation from vertical drilling into the stratum to horizontal drilling into the coal seam, crush the coal seam into coal powder, burn and gasify the coal powder, and realize the integrated operation of coal seam drilling and gasification.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] An underground coal gasification drilling mining process specifically comprises the following steps:

[0007] (1) At a pre-set construction site, the new underground coal gasification mining system is operated to drill vertically into the stratum, breaking the stratum into soil debris and discharging it to the ground to form a vertical borehole;

[0008] (2) When the new underground coal gasification mining system drills down into the coal seam, the drilling direction is changed so that the new underground coal gasification mining system drills in a certain horizontal direction in the coal seam to crush the coal seam into coal powder;

[0009] (3) The crushed coal powder is burned and gasified in a new underground coal gasification mining system, and the synthesis gas generated after combustion is transported to the ground gas gathering station for further processing;

[0010] (4) After the new underground coal gasification mining system drills along a certain horizontal direction of the coal seam to the end of the coal seam, it is withdrawn to the coal seam below the vertical drill hole, and the drilling direction is changed, so that the new underground coal gasification mining system drills along another horizontal direction in the coal seam to crush the coal seam into coal powder and gasify it again. After drilling through, it is withdrawn again and the drilling direction in the coal seam is changed to gasify it. In this way, the entire coal seam in the mining area can be gasified by repeating the operation;

[0011] The new underground coal gasification mining system includes a first guide cylinder, a second guide cylinder, a drilling and crushing device and a combustion gasification device. The first guide cylinder and the second guide cylinder are concentric and vertically arranged. The lower side of the first guide cylinder and the upper side and lower side of the second guide cylinder are open. The top of the first guide cylinder and the bottom of the second guide cylinder are fixedly connected. The drilling and crushing device is concentrically installed on the inner bottom of the first guide cylinder, and the combustion gasification device is concentrically fixedly installed in the second guide cylinder. A plurality of formation through holes in a circumferential array are provided on the top plate of the first guide cylinder. The first guide cylinder is connected with the annular cavity between the second guide cylinder and the combustion gasification device through each formation through hole. A coal seam through hole is provided in the center of the top plate of the first guide cylinder. The lower end of the combustion gasification device is fixedly connected to the coal seam through hole. A formation sealing device for sealing each formation through hole is provided in the first guide cylinder. A plurality of reducing and steering devices are provided on the outer circumference of the upper side of the second guide cylinder. The structures of the reducing and steering devices are the same and are arranged in a circumferential array.

[0012] The first guide cylinder and the second guide cylinder are both stepped cylinder structures with a smaller upper portion and a larger lower portion. The outer diameter of the upper cylinder of the first guide cylinder is equal to the outer diameter of the lower cylinder of the second guide cylinder. Spiral ridges are evenly arranged on the outer circumference of the upper cylinder of the first guide cylinder.

[0013] The drilling and crushing device includes a rotating cylinder and a driven internal gear. The rotating cylinder is coaxially arranged at the bottom of the lower cylinder of the first guide cylinder. The top of the rotating cylinder is open, and the outer circle of the rotating cylinder is in sliding contact with the inner circle of the lower cylinder of the first guide cylinder. A limiting ring groove is circumferentially provided on the middle part of the outer circle of the rotating cylinder. A plurality of limiting screws are threadedly connected on the outer circumference of the lower cylinder of the first guide cylinder. Each limiting screw is respectively arranged along the radial direction of the first guide cylinder. The inner end of each limiting screw passes through the lower cylinder wall of the first guide cylinder and extends into the limiting ring groove. The driven internal gear is coaxially arranged in the lower cylinder of the first guide cylinder and is located above the rotating cylinder. The inner diameter of the internal gear is the same as the inner diameter of the rotating cylinder, the outer diameter of the driven internal gear is not larger than the outer diameter of the rotating cylinder, the bottom of the driven internal gear and the top of the rotating cylinder are fixedly connected by a number of vertical connecting plates, and a number of motor fixing plates in a circumferential array are integrally formed on the lower side of the inner circle of the upper cylinder of the first guide cylinder. A rotary reduction motor is fixedly installed on each motor fixing plate, and the output shaft of each rotary reduction motor is vertically arranged. The output shaft of each rotary reduction motor passes downward through the motor fixing plate and extends into the interior of the driven internal gear, and the lower end of the output shaft of each rotary reduction motor is fixedly installed with a driving external gear that meshes with the driven internal gear for transmission. The lower surface of the bottom plate of the rotating cylinder is flush with the bottom of the lower cylinder of the first guide cylinder. A number of rigid ball protrusions are evenly arranged on the lower surface of the bottom plate of the rotating cylinder. A polygonal hollow prism is integrally formed in the middle of the upper surface of the bottom plate of the rotating cylinder. A number of vertical support plates are fixedly connected to the outer edge of the upper surface of the bottom plate of the rotating cylinder. Each vertical support plate is arranged in a circular array. Each vertical support plate is parallel to each side of the polygonal hollow prism. A horizontal crushing reduction motor is fixedly installed on the outer surface of each vertical support plate. The output shaft of each horizontal crushing reduction motor is arranged along the radial direction of the rotating cylinder. Each horizontal crushing reduction motor is respectively connected to the polygon The side faces of the hollow prism correspond one to one in the radial direction of the rotating cylinder, and the output shafts of the horizontal crushing reduction motors pass through the corresponding vertical support plates respectively. The output shafts of the horizontal crushing reduction motors are coaxially connected to a horizontal cutting shaft. The inner ends of the horizontal cutting shafts are rotatably mounted on the corresponding side faces of the polygonal hollow prism. Cutting blades are spirally arranged axially on the outer circumference of the horizontal cutting shafts. A number of rectangular through holes that are transparent from top to bottom and arranged in a circular array are provided on the bottom plate of the rotating cylinder. The length direction of the rectangular through holes is arranged along the radial direction of the rotating cylinder, and each rectangular through hole is located directly below each horizontal cutting shaft.

[0014] The combustion gasification device includes a gasification chamber, a coalbed methane output pipe and an oxygen delivery pipe. The gasification chamber is a cylindrical structure that is transparent from top to bottom. The gasification chamber is vertically arranged inside the lower tube of the second guide tube with the same center. The lower end of the gasification chamber is fixedly connected to the coal seam tube. The lower end of the coal seam tube is fixedly connected to the coal seam through hole. The coalbed methane output pipe is arranged inside the upper tube of the second guide tube with the same center. The lower end of the coalbed methane output pipe is fixedly connected to the upper end of the gasification chamber. The oxygen delivery pipe is fixedly sleeved on the outer circumference of the coalbed methane output pipe with the same center. An oxygen supply annular cavity is formed between the inner circle of the oxygen delivery pipe and the outer circle of the coalbed methane output pipe. The lower end of the oxygen delivery pipe is fixedly connected to an annular sealing plate sleeved on the coalbed methane output pipe. The inner circle of the annular sealing plate is fixedly connected to the outer circle of the coalbed methane output pipe. A plurality of vertical oxygen dividing boxes are arranged in a circumferential array inside the lower tube of the second guide tube. The gasification chamber is located in the middle of each of the dry vertical oxygen dividing boxes. The outer circumference of the lower side of the oxygen delivery pipe is fixedly connected There are several oxygen branch pipes in a circular array, and the lower end of each oxygen branch pipe is fixedly connected to the top of each vertical oxygen dividing box. Each vertical oxygen dividing box is fixedly connected to the gasification chamber through several horizontal oxygen supply pipes arranged up and down. The inner end of each horizontal oxygen supply pipe passes through the wall of the gasification chamber and extends into the gasification chamber. The inner end of each horizontal oxygen supply pipe is fixedly installed with a nozzle that sprays toward the center of the gasification chamber. Several ignition electrodes in a circular array are fixedly arranged on the lower inner wall of the gasification chamber. The inner lower part of the coal seam barrel is rotatably connected to a disc-shaped coal seam channel plugging plate. The left and right sides of the circular circumference of the disc-shaped coal seam channel plugging plate are fixedly connected to a rotating shaft rotatably set on the wall of the coal seam barrel. Two coal seam channel servos are fixedly installed on the outer circumference of the lower side of the coal seam barrel. The two coal seam channel servos are symmetrically arranged on both sides of the coal seam barrel. The output shafts of the two coal seam channel servos are synchronously driven and connected to the left and right rotating shafts respectively.

[0015] The stratum sealing device includes a hydraulic cylinder and a stratum sealing plate. The hydraulic cylinder is vertically arranged in the lower tube of the first guide tube with the same center. The outer circumference of the top of the polygonal hollow prism is fixedly connected to the first fixed seat through a number of support rods. The hydraulic cylinder is fixedly installed on the first fixed seat. The stratum sealing plate is a disc-shaped plate. The stratum sealing plate is horizontally arranged in the upper tube of the first guide tube with the same center. The piston rod of the hydraulic cylinder extends vertically upward. The bottom center of the stratum sealing plate is fixedly connected to the upper end of the piston rod of the hydraulic cylinder. Three fan-shaped through holes are evenly opened on the stratum sealing plate. The three fan-shaped through holes are arranged in a circular array. The diameter of the stratum sealing plate is larger than the diameter of the circle where the outermost quadrant points of each stratum through hole are located and smaller than the inner diameter of the upper tube of the first guide tube. The outer arc diameter of the fan-shaped through hole is equal to the diameter of the circle where the innermost quadrant points of each stratum through hole are located, and the inner arc diameter of the fan-shaped through hole is smaller than the diameter of the coal seam through hole.

[0016] The front diameter-changing steering device includes a second fixed seat, a guide reduction motor, two guide light bars, a guide screw, a screw nut, a slider, an L-shaped guide plate, a hinged support and a diameter-changing moving block. The upper side and lower side of the outer circumference of the upper cylinder of the second guide cylinder are fixedly connected with an annular flange. The second fixed seat is fixedly connected to the lower side of the upper annular flange. The guide reduction motor, the guide screw and the two guide light bars are all vertically arranged. The guide reduction motor is fixedly installed on the second fixed seat. The L-shaped guide plate includes a horizontal plate and a vertical plate. The front side of the flat plate is fixedly connected to the upper side of the vertical plate, the lower end of the output shaft of the guide reduction motor is transmission-connected to the upper end of the guide screw, the lower end of the guide screw is rotatably connected to the horizontal plate of the L-shaped guide plate, and the two guide light bars are symmetrically arranged on both sides of the guide reduction motor. The upper ends of the two guide light bars are fixedly connected to the annular flange on the upper side, and the lower ends of the two guide light bars are fixedly connected to the annular flange on the lower side. The left and right sides of the vertical plate of the L-shaped guide plate are respectively fixedly connected to the two guide light bars and are located on the two guide light bars. The two guide light bars pass through the left and right sides of the slider respectively, the slider is slidably connected to the two guide light bars, the screw nut is sleeved on the guide screw and is threadedly connected to the guide screw, the front side of the screw nut is fixedly connected to the middle of the slider by a screw, the hinged support is fixedly installed on the upper side of the annular flange on the lower side by screws and is located between the two guide light bars, the lower ends of the two guide light bars pass through the left and right sides of the hinged support respectively, the diameter-reducing moving block is arranged in front of the vertical plate of the L-shaped guide plate, and the diameter-reducing moving block is arranged in front of the vertical plate of the L-shaped guide plate. A horizontal limit rod is fixedly connected to the middle part of the rear side of the moving block, and a vertical guide long hole that is transparent to the front and back is opened on the vertical plate of the L-shaped guide plate. The rear side of the horizontal limit rod passes through the vertical guide long hole, and the upper and lower sides of the variable diameter moving block are hinged with a connecting rod. The upper end of the upper connecting rod is hinged to the lower side of the slider, and the lower end of the lower connecting rod is hinged to the hinged support. A guide skin is fixedly installed between the two annular flanges and is mounted on the outside of the upper tube of the second guide tube. The outer side surface of the variable diameter moving block presses against the inner side surface of the guide skin.

[0017] A sealing cover is provided on the outside of the driven internal gear and each driving external gear, and a gas sensor is provided on the inner wall of the first guide cylinder.

[0018] The upper end of the second guide cylinder is fixedly connected to several sections of the first pipe string, the upper end of the oxygen delivery pipe is fixedly connected to several sections of the second pipe string, and the upper end of the coalbed methane output pipe is fixedly connected to several sections of the third pipe string. The first pipe string is concentrically sleeved on the outside of the second pipe string, and the second pipe string is concentrically sleeved on the outside of the third pipe string. Radial support ribs are arranged between the outer circle of the third pipe string and the inner circle of the second pipe string, and between the outer circle of the second pipe string and the inner circle of the first pipe string. The upper ends of the first pipe string, the second pipe string and the third pipe string are all provided with internal threaded female heads, and the lower ends of the first pipe string, the second pipe string and the third pipe string are all provided with external threaded male heads. Two adjacent sections of the first pipe string, two adjacent sections of the second pipe string and two adjacent sections of the third pipe string are all fixedly connected and sealed by internal threaded female heads and external threaded male heads.

[0019] Step (1) is specifically as follows: first, the new underground coal gasification mining system is vertically set, the bottom of the rotating cylinder contacts the ground, the two coal seam channel servos drive the two rotating shafts to rotate the disc-shaped coal seam channel plug to a horizontal state, the disc-shaped coal seam channel plug seals the coal seam cylinder, the piston rod of the hydraulic cylinder is in a retracted state, so that the formation plug is separated from the inner surface of the top plate of the first guide cylinder and has a large distance, each formation through hole is in a transparent state, the first guide cylinder is connected to the annular cavity between the second guide cylinder and the combustion gasification device through each formation through hole, then, each rotating reduction motor is started synchronously, the output shaft of each rotating reduction motor drives each active external gear to rotate synchronously, each active external gear synchronously drives the driven internal gear to rotate, the driven internal gear drives the rotating cylinder to rotate synchronously, each rigid ball protrusion on the lower surface of the bottom plate of the rotating cylinder coarsely crushes the formation, and the coarsely crushed soil particles enter the rotating cylinder upward through each rectangular through hole, in this process, each horizontal crushing reduction motor rotates synchronously and drives each horizontal cutting shaft, each horizontal cutting The cutting blades on the shaft rotate and realize secondary crushing of the coarsely crushed soil particles. The upper port of the annular cavity between the first pipe string and the second pipe string is connected to the exhaust port of the exhaust fan on the ground. The exhaust fan is started to draw the secondary crushed soil particles into the annular cavity between the second guide cylinder and the combustion gasification device through the through holes of each formation, and then draw them upward to the ground through the annular cavity between the second guide cylinder and the gasification chamber, the coalbed methane output pipe and the oxygen delivery pipe, and the annular cavity between the first pipe string and the second pipe string. The outer circumference of the upper side of the first guide cylinder is The spiral ridges cut the inner wall of the vertical borehole, so that the outer circle of the first guide cylinder and the inner wall of the vertical borehole form an annular cavity for ventilation. It can also reduce the contact area between the outer circumference of the first guide cylinder and the inner wall of the vertical borehole, and reduce the friction resistance during the drilling process. The drilling process is achieved by connecting a single first pipe string, a second pipe string and a third pipe string to the upper end of the second guide cylinder, the upper end of the oxygen delivery pipe and the upper end of the coalbed methane output pipe, respectively, and simultaneously buckling and continuously connecting multiple sections of the first pipe string, the second pipe string and the third pipe string to advance forward.

[0020] Step (2) is specifically as follows: when the gas sensor detects gas, it indicates that the bottom of the rotating cylinder has drilled into the coal seam, then the vertical drilling is changed to horizontal drilling, and the guide reduction motors on the side of the outer circumference of the upper cylinder of the second guide cylinder are controlled to move forward, and the guide reduction motors on the side of the outer circumference of the upper cylinder of the second guide cylinder synchronously drive the corresponding guide screws to rotate forward, driving the corresponding screw nuts to drive the corresponding sliders to move downward, so that the corresponding variable-diameter moving blocks are all extended outward to press the guide skin and act on the well wall, and the corresponding variable-diameter moving blocks can act in the opposite direction on the side of the outer circumference of the upper cylinder of the second guide cylinder under the action of the well wall. When the cam is in the air, the guide shaft is moved in an opposite direction so that the cam can move ...

[0021] Step (3) is specifically as follows: when drilling into the coal seam and the drilling direction becomes horizontal, the two coal seam channel servos drive the two rotating shafts to rotate the disc-shaped coal seam channel plugging plate to a vertical state, then the channel of the coal seam barrel is opened, and the piston rod of the hydraulic cylinder extends upward, so that the formation plugging plate moves upward until it is in tight contact with the inner surface of the top plate of the first guide barrel, and each formation through hole is blocked. The first guide barrel is connected to the coal seam barrel through the coal seam through hole, and then the first guide barrel is connected to the gasification chamber. The rigid ball protrusions on the lower surface of the bottom plate of the rotating barrel coarsely crush the coal seam, and the coarsely crushed coal particles enter the rotating barrel upward through each rectangular through hole, and the cutting blades on each transverse cutting shaft rotate to realize the second crushing of the coarsely crushed coal particles. The coal particles are crushed once, and the secondary crushed coal particles become coal powder and enter the coal seam barrel through three fan-shaped through holes and the coal seam through hole, and then enter the gasification chamber through the coal seam barrel. At the same time, oxygen is transported downward from the ground through the oxygen delivery pipe, and the oxygen enters each vertical oxygen dividing box through the oxygen branch pipe. The oxygen in each vertical oxygen dividing box then enters the gasification chamber through each horizontal oxygen supply pipe. The oxygen is evenly sprayed toward the center of the gasification chamber through each nozzle, so that the oxygen and the coal powder in the gasification chamber are fully contacted and mixed. The mixture of coal powder and oxygen in the gasification chamber is ignited by each ignition electrode to realize the combustion and gasification of the coal powder. The synthesis gas generated after combustion is transported to the ground gas gathering station through the coalbed methane output pipe for further processing;

[0022] Step (4) is specifically as follows: according to the method of drilling a horizontal well, after the new underground coal gasification mining system is drilled along a certain horizontal direction of the coal seam to the end of the coal seam, the multiple sections of the first pipe string, the second pipe string and the third pipe string are unhooked, so that the new underground coal gasification mining system is gradually withdrawn to the coal seam below the vertical borehole, and step (2) is repeated, so that the lower side of the first guide cylinder is tilted in another direction, and drilling is continued, thereby changing the drilling direction again, so that the new underground coal gasification mining system is drilled in the coal seam along another horizontal direction, the coal seam is crushed into coal powder, and gasified again. After drilling through, the system is withdrawn again and the drilling direction in the coal seam is changed to gasify. In this way, the operation is repeated, and all the coal seams in the mining area can be gasified. The process of horizontal drilling and gasification in the coal seam is the same as step (3) and will not be repeated.

[0023] The present invention can realize the transformation from vertical stratum drilling to horizontal coal seam drilling, crush the coal seam into coal powder, burn and gasify the coal powder, and realize the integrated operation of coal seam drilling and gasification. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the operation of the present invention in strata and coal seams.

[0025] Figure 2 It is a bottom view of the present invention.

[0026] Figure 3 It is a front view of the present invention.

[0027] Figure 4 It is a structural schematic diagram of the drilling and crushing device and the formation sealing device of the present invention.

[0028] Figure 5 It is a structural schematic diagram of the combustion gasification device and various diameter-changing turning devices of the present invention.

[0029] Figure 6 It is a structural schematic diagram of a single variable diameter steering device of the present invention.

[0030] Figure 7 yes Figure 1 A partial enlarged view of point A in the middle.

[0031] Figure 8 yes Figure 1 A partial enlarged view of point B in the middle.

[0032] Figure 9 yes Figure 1 A partial enlarged view of point C in the middle.

[0033] Figure 10 It is a schematic structural diagram of the present invention for drilling in coal seams. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are further described below with reference to the accompanying drawings.

[0035] like Figures 1-10 As shown, an underground coal gasification drilling mining process specifically includes the following steps:

[0036] (1) At a pre-set construction site, the new underground coal gasification mining system 53 is operated to drill vertically into the stratum 51 in a vertical direction, breaking the stratum 51 into soil residue and discharging it to the ground, thereby forming a vertical borehole 54;

[0037] (2) When the new underground coal gasification mining system 53 drills down into the coal seam 52, the drilling direction is changed so that the new underground coal gasification mining system 53 drills in the coal seam 52 along a certain horizontal direction to crush the coal seam 52 into coal powder;

[0038] (3) The crushed coal powder is burned and gasified in the new underground coal gasification mining system 53, and the synthesis gas generated after combustion is transported to the ground gas gathering station for further processing;

[0039] (4) After the new underground coal gasification mining system 53 drills along a certain horizontal direction of the coal seam 52 to the end of the coal seam 52, the new underground coal gasification mining system 53 is withdrawn to the coal seam 52 below the vertical borehole 54, and the drilling direction is changed so that the new underground coal gasification mining system 53 drills along another horizontal direction in the coal seam 52 to crush the coal seam 52 into coal powder and gasify it again. After drilling through, the system is withdrawn again and the drilling direction in the coal seam 52 is changed to gasify it. In this way, the entire coal seam in the mining area can be gasified by repeating the operation.

[0040] The new underground coal gasification mining system 53 includes a first guide cylinder 1, a second guide cylinder 2, a drilling and crushing device and a combustion gasification device. The first guide cylinder 1 and the second guide cylinder 2 are concentric and vertically arranged. The lower side of the first guide cylinder 1 and the upper and lower sides of the second guide cylinder 2 are open. The top of the first guide cylinder 1 and the bottom of the second guide cylinder 2 are fixedly connected. The drilling and crushing device is concentrically installed on the inner bottom of the first guide cylinder 1, and the combustion gasification device is concentrically fixedly installed in the second guide cylinder 2. A plurality of formation through holes 3 in a circumferential array are opened on the top plate of the first guide cylinder 1. The first guide cylinder 1 is connected to the annular cavity between the second guide cylinder 2 and the combustion gasification device through each formation through hole 3. A coal seam through hole 4 is opened in the center of the top plate of the first guide cylinder 1. The lower end of the combustion gasification device is fixedly connected to the coal seam through hole 4. A formation plugging device for sealing each formation through hole 3 is provided in the first guide cylinder 1. A plurality of reducing and steering devices are provided on the outer circumference of the upper side of the second guide cylinder 2. The structures of the reducing and steering devices are the same and are arranged in a circumferential array.

[0041] The first guide cylinder 1 and the second guide cylinder 2 are both stepped cylinder structures with a smaller upper portion and a larger lower portion. The outer diameter of the upper cylinder of the first guide cylinder 1 is equal to the outer diameter of the lower cylinder of the second guide cylinder 2. Spiral ridges 5 are evenly arranged on the outer circumference of the upper cylinder of the first guide cylinder 1.

[0042] The drilling and crushing device includes a rotating cylinder 6 and a driven internal gear 7. The rotating cylinder 6 is coaxially rotated and arranged at the bottom of the lower cylinder of the first guide cylinder 1. The top of the rotating cylinder 6 is open. The outer circle of the rotating cylinder 6 is in sliding contact with the inner circle of the lower cylinder of the first guide cylinder 1. A limiting ring groove 8 is circumferentially provided in the middle part of the outer circle of the rotating cylinder 6. A plurality of limiting screws 9 are threadedly connected on the outer circumference of the lower cylinder of the first guide cylinder 1. Each limiting screw 9 is respectively arranged along the radial direction of the first guide cylinder 1. The inner end of each limiting screw 9 passes through the lower cylinder wall of the first guide cylinder 1 and extends into the limiting ring groove 8. The driven internal gear 7 is coaxially arranged in the lower cylinder of the first guide cylinder 1 and is located above the rotating cylinder 6. The inner diameter of the driven internal gear 7 The inner diameter of the driven internal gear 7 is the same as the inner diameter of the rotating cylinder 6, and the outer diameter of the driven internal gear 7 is not larger than the outer diameter of the rotating cylinder 6. The bottom of the driven internal gear 7 and the top of the rotating cylinder 6 are fixedly connected by several vertical connecting plates 10. The lower side of the inner circle of the upper cylinder of the first guide cylinder 1 is integrally formed with several motor fixing plates 11 in a circumferential array. A rotary reduction motor 12 is fixedly installed on each motor fixing plate 11. The output shaft of each rotary reduction motor 12 is vertically arranged. The output shaft of each rotary reduction motor 12 passes downward through the motor fixing plate 11 and extends into the interior of the driven internal gear 7. The lower end of the output shaft of each rotary reduction motor 12 is fixedly installed with a driving external gear 13 that meshes with the driven internal gear 7. The rotating cylinder 6 The lower surface of the bottom plate is flush with the bottom of the lower side of the first guide cylinder 1, and a number of rigid ball protrusions 14 are evenly arranged on the lower surface of the bottom plate of the rotating cylinder 6. A polygonal hollow prism 15 is integrally formed in the middle of the upper surface of the bottom plate of the rotating cylinder 6. A number of vertical support plates 16 are fixedly connected to the outer edge of the upper surface of the bottom plate of the rotating cylinder 6. Each vertical support plate 16 is arranged in a circular array. Each vertical support plate 16 is parallel to each side of the polygonal hollow prism 15. A horizontal crushing reduction motor 17 is fixedly installed on the outer surface of each vertical support plate 16. The output shaft of each horizontal crushing reduction motor 17 is arranged along the radial direction of the rotating cylinder 6. Each horizontal crushing reduction motor 17 is respectively connected to the polygonal hollow prism. The side surfaces of 15 correspond one to one in the radial direction of the rotating cylinder 6, and the output shafts of the horizontal crushing reduction motors 17 pass through the corresponding vertical support plates 16 respectively. The output shafts of the horizontal crushing reduction motors 17 are coaxially connected to a horizontal cutting shaft 18. The inner ends of the horizontal cutting shafts 18 are rotatably mounted on the corresponding side surfaces of the polygonal hollow prism 15. A cutting blade 19 is spirally arranged axially on the outer circumference of the horizontal cutting shaft 18. A number of rectangular through holes 20 that are transparent from top to bottom and arranged in a circumferential array are provided on the bottom plate of the rotating cylinder 6. The length direction of the rectangular through holes 20 is arranged along the radial direction of the rotating cylinder 6, and each rectangular through hole 20 is located directly below each horizontal cutting shaft 18.

[0043] The combustion gasification device includes a gasification chamber 21, a coalbed methane output pipe 22 and an oxygen delivery pipe 23. The gasification chamber 21 is a cylindrical structure that is transparent from top to bottom. The gasification chamber 21 is vertically arranged in the lower tube of the second guide tube 2 with the same center. The lower end of the gasification chamber 21 is fixedly connected to the coal seam tube 24. The lower end of the coal seam tube 24 is fixedly connected to the coal seam through hole 4. The coalbed methane output pipe 22 is concentrically arranged in the upper tube of the second guide tube 2. The lower end of the coalbed methane output pipe 22 is fixedly connected to the upper end of the gasification chamber 21. The oxygen delivery pipe 23 is fixedly sleeved in the same center. On the outer circumference of the coalbed methane output pipe 22, an oxygen supply annular cavity is formed between the inner circle of the oxygen delivery pipe 23 and the outer circle of the coalbed methane output pipe 22. The lower end of the oxygen delivery pipe 23 is fixedly connected to an annular sealing plate 25 sleeved on the coalbed methane output pipe 22. The inner circle of the annular sealing plate 25 is fixedly connected to the outer circle of the coalbed methane output pipe 22. A plurality of vertical oxygen dividing boxes 26 are arranged in an array on the inner circumference of the lower cylinder of the second guide cylinder 2. The gasification chamber 21 is located in the middle of each of the vertical oxygen dividing boxes 26. The outer circumference of the lower side of the oxygen delivery pipe 23 is fixed. A plurality of oxygen branch pipes 27 are connected in a circumferential array. The lower end of each oxygen branch pipe 27 is fixedly connected to the top of each vertical oxygen dividing box 26. Each vertical oxygen dividing box 26 is fixedly connected to the vaporization chamber 21 through a plurality of horizontal oxygen supply pipes 28 arranged up and down. The inner end of each horizontal oxygen supply pipe 28 passes through the wall of the vaporization chamber 21 and extends into the vaporization chamber 21. The inner end of each horizontal oxygen supply pipe 28 is fixedly installed with a nozzle 29 that sprays toward the center of the vaporization chamber 21. The lower end of the vaporization chamber 21 is fixed with a nozzle 29 that sprays toward the center of the vaporization chamber 21. A number of ignition electrodes 30 in a circular array are fixedly installed on the inner side wall. A disc-shaped coal seam channel blocking plate 31 is rotatably connected to the inner lower part of the coal seam barrel 24. The left and right sides of the circular circumference of the disc-shaped coal seam channel blocking plate 31 are fixedly connected to a rotating shaft rotatably set on the wall of the coal seam barrel 24. Two coal seam channel servos 32 are fixedly installed on the outer circumference of the lower side of the coal seam barrel 24. The two coal seam channel servos 32 are symmetrically arranged on both sides of the coal seam barrel 24. The output shafts of the two coal seam channel servos 32 correspond to the left and right rotating shafts connected to the synchronous transmission.

[0044] The stratum plugging device includes a hydraulic cylinder 33 and a stratum plugging plate 34. The hydraulic cylinder 33 is vertically arranged in the lower cylinder of the first guide cylinder 1 with the same center. The top outer circumference of the polygonal hollow prism 15 is fixedly connected to the first fixed seat 35 through a plurality of support rods. The hydraulic cylinder 33 is fixedly installed on the first fixed seat 35. The stratum plugging plate 34 is a disc-shaped plate. The stratum plugging plate 34 is horizontally arranged in the upper cylinder of the first guide cylinder 1 with the same center. The piston rod of the hydraulic cylinder 33 extends vertically upward. The stratum plugging plate 34 is fixedly mounted on the first fixed seat 35. The bottom center is fixedly connected to the upper end of the piston rod of the hydraulic cylinder 33. Three fan-shaped through holes 36 are evenly opened on the formation sealing plate 34. The three fan-shaped through holes 36 are arranged in a circular array. The diameter of the formation sealing plate 34 is larger than the diameter of the circle where the outermost quadrant points of each formation through hole 3 are located and smaller than the inner diameter of the upper tube of the first guide tube 1. The outer arc diameter of the fan-shaped through hole 36 is equal to the diameter of the circle where the innermost quadrant points of each formation through hole 3 are located, and the inner arc diameter of the fan-shaped through hole 36 is smaller than the diameter of the coal seam through hole 4.

[0045] The front diameter-changing steering device includes a second fixed seat 37, a guide reduction motor 38, two guide light bars 39, a guide screw 40, a screw nut 41, a slider 42, an L-shaped guide plate 43, a hinged support 44 and a diameter-changing moving block 45. The upper and lower sides of the outer circumference of the upper tube of the second guide cylinder 2 are fixedly connected with an annular flange 46. The second fixed seat 37 is fixedly connected to the lower side of the upper annular flange 46. The guide reduction motor 38, the guide screw 40 and the two guide light bars 39 are all arranged vertically. The guide reduction motor 38 is fixedly mounted on the second fixed seat 37. The L-shaped guide plate 43 includes a horizontal plate and The vertical plate and the front side of the horizontal plate are integrally fixedly connected to the upper side of the vertical plate. The lower end of the output shaft of the guide reduction motor 38 is transmission-connected to the upper end of the guide screw 40. The lower end of the guide screw 40 is rotatably connected to the horizontal plate of the L-shaped guide plate 43. The two guide light bars 39 are symmetrically arranged on both sides of the guide reduction motor 38. The upper ends of the two guide light bars 39 are fixedly connected to the annular flange 46 on the upper side. The lower ends of the two guide light bars 39 are fixedly connected to the annular flange 46 on the lower side. The left and right sides of the vertical plate of the L-shaped guide plate 43 are respectively fixedly connected to the two guide light bars 39 and are located on the two guide light bars 39. The two guide light bars 39 pass through the left and right sides of the slider 42 respectively. The slider 42 is slidably connected to the two guide light bars 39. The screw nut 41 is sleeved on the guide screw 40 and is threadedly connected to the guide screw 40. The front side of the screw nut 41 is fixedly connected to the middle of the slider 42 by screws. The hinged support 44 is fixedly installed on the upper side of the annular flange 46 on the lower side by screws and is located between the two guide light bars 39. The lower ends of the two guide light bars 39 pass through the left and right sides of the hinged support 44 respectively. The diameter-changing moving block 45 is arranged in front of the vertical plate of the L-shaped guide plate 43. A horizontal limit rod 47 is fixedly connected to the middle of the rear side of block 45. A vertical guide slot 48, which is transparent from front to back, is provided on the vertical plate of the L-shaped guide plate 43. The rear side of the horizontal limit rod 47 passes through the vertical guide slot 48. A connecting rod 49 is hinged to the upper and lower sides of the variable diameter movable block 45. The upper end of the upper connecting rod 49 is hinged to the lower side of the slider 42, and the lower end of the lower connecting rod 49 is hinged to the hinge support 44. A guide skin 50, which is mounted on the outer side of the upper tube of the second guide tube 2, is fixedly installed between the two annular flanges 46. The outer side of the variable diameter movable block 45 presses against the inner side of the guide skin 50. The horizontal limit rod 47 guides the movement trajectory of the variable diameter movable block 45, while the guide skin 50 provides a sealed guide.

[0046] A sealed housing is provided outside the driven internal gear 7 and each driving external gear 13, and a gas sensor is provided on the inner wall of the first guide cylinder 1. The sealed housing prevents soil particles or coal gangue particles from entering the meshing area between each driving external gear 13 and the driven internal gear 7 and damaging the tooth surfaces.

[0047] The upper end of the second guide cylinder 2 is fixedly connected to several sections of the first pipe string 55, the upper end of the oxygen delivery pipe 23 is fixedly connected to several sections of the second pipe string, and the upper end of the coalbed methane output pipe 22 is fixedly connected to several sections of the third pipe string. The first pipe string 55 is concentrically sleeved on the outside of the second pipe string, and the second pipe string is concentrically sleeved on the outside of the third pipe string. Radial support ribs are interspersed between the outer circle of the third pipe string and the inner circle of the second pipe string, and between the outer circle of the second pipe string and the inner circle of the first pipe string 55. The upper ends of the first pipe string 55, the second pipe string, and the third pipe string are all provided with internal threaded female heads, and the lower ends of the first pipe string 55, the second pipe string, and the third pipe string are all provided with external threaded male heads. Adjacent sections of the first pipe string 55, adjacent sections of the second pipe string, and adjacent sections of the third pipe string are all threadedly fixedly connected and sealed by the internal threaded female heads and external threaded male heads. Pipe string sealing is an existing mature technology and will not be described in detail.

[0048] Step (1) is specifically as follows: first, the new underground coal gasification mining system 53 is vertically arranged, the bottom of the rotating cylinder 6 is in contact with the ground, the two coal seam channel steering gears 32 drive the two rotating shafts to rotate the disc-shaped coal seam channel plugging plate 31 to a horizontal state, the disc-shaped coal seam channel plugging plate 31 blocks the coal seam cylinder 24, the piston rod of the hydraulic cylinder 33 is in a retracted state, so that the formation plugging plate 34 is separated from the inner surface of the top plate of the first guide cylinder 1 and has a large distance, each formation through hole 3 is in a transparent state, and the first guide cylinder 1 passes through each formation through hole 3 and the annular cavity between the second guide cylinder 2 and the combustion gasification device Then, each rotary reduction motor 12 is started synchronously, and the output shaft of each rotary reduction motor 12 drives each active external gear 13 to rotate synchronously, and each active external gear 13 drives the driven internal gear 7 to rotate synchronously, and the driven internal gear 7 drives the rotating drum 6 to rotate synchronously. Each rigid ball protrusion 14 on the lower surface of the bottom plate of the rotating drum 6 roughly crushes the stratum 51, and the roughly crushed soil particles pass through each rectangular through hole 20 and enter the rotating drum 6 upward. In this process, each horizontal crushing reduction motor 17 rotates synchronously and drives each horizontal cutting shaft 18. The cutting blade 19 rotates and realizes secondary crushing of the coarsely crushed soil particles. The upper end of the annular cavity between the first pipe string 55 and the second pipe string is connected to the exhaust port of the exhaust fan on the ground. The exhaust fan is started to draw the secondary crushed soil particles into the annular cavity between the second guide cylinder 2 and the combustion gasification device through each formation through hole 3, and then through the annular cavity between the second guide cylinder 2 and the gasification chamber 21, the coalbed methane output pipe 22 and the oxygen delivery pipe 23, and the annular cavity between the first pipe string 55 and the second pipe string to the ground. The spiral ribs 5 on the outer circumference of the upper side of the first guide cylinder 1 cut The inner wall of the vertical borehole 54 is cut so that the outer circle of the first guide cylinder 1 and the inner wall of the vertical borehole 54 form an annular cavity for ventilation. It can also reduce the contact area between the outer circumference of the first guide cylinder 1 and the inner wall of the vertical borehole 54, and reduce the friction resistance during drilling. The drilling process is achieved by connecting a single first pipe string 55, a second pipe string and a third pipe string to the upper end of the second guide cylinder 2, the upper end of the oxygen delivery pipe 23 and the upper end of the coalbed methane output pipe 22, respectively, and simultaneously buckling and continuously connecting multiple sections of the first pipe string 55, the second pipe string and the third pipe string to advance forward. This process is a conventional technology in drilling operations.

[0049] Step (2) is specifically as follows: when the gas sensor detects gas overflowing from the coal seam, it indicates that the bottom of the rotating cylinder 6 has drilled into the coal seam 52, and the vertical drilling is changed to horizontal drilling, and the guide reduction motors 38 on the side of the outer circumference of the upper side of the second guide cylinder 2 are controlled to move forward. The guide reduction motors 38 on the side of the outer circumference of the upper side of the second guide cylinder 2 synchronously drive the corresponding guide screws 40 to rotate forward, driving the corresponding screw nuts 41 to drive the corresponding sliders 42 to move downward, so that the corresponding variable-diameter moving blocks 45 are all extended outward to press the guide skin 50 and act on the well wall. Under the action of the well wall, the corresponding variable-diameter moving blocks 45 can act in the opposite direction on the outer circumference of the upper side of the second guide cylinder 2. On one side of the circumference, the guide reduction motors 38 on the other side of the upper outer circumference of the second guide cylinder 2 are controlled to move in reverse. The guide reduction motors 38 on the other side of the upper outer circumference of the second guide cylinder 2 synchronously drive the corresponding guide screws 40 to rotate in the opposite direction, driving the corresponding screw nuts 41 to drive the corresponding sliders 42 to move upward, so that the corresponding variable-diameter moving blocks 45 are all retracted inward. In this way, the side of the upper outer circumference of the second guide cylinder 2 can be tilted to the other side, and then the lower side of the first guide cylinder 1 can be tilted to the opposite side. Continuing to drill downward can realize the change of drilling direction, thereby realizing the change from vertical drilling in the formation 51 to horizontal drilling along a certain side in the coal seam 52.

[0050] Step (3) is specifically as follows: when drilling into the coal seam 52 and the drilling direction becomes horizontal, the two coal seam channel servos 32 drive the two rotating shafts to rotate the disc-shaped coal seam channel plugging plate 31 to a vertical state, then the channel of the coal seam barrel 24 is opened, and the piston rod of the hydraulic cylinder 33 extends upward, so that the formation plugging plate 34 moves upward to be in tight contact with the inner surface of the top plate of the first guide cylinder 1, and each formation through hole 3 is blocked. The first guide cylinder 1 is connected to the coal seam barrel 24 through the coal seam through hole 4, and then the first guide cylinder 1 is connected to the gasification chamber 21. The rigid ball protrusions 14 on the lower surface of the bottom plate of the rotating cylinder 6 coarsely crush the coal seam 52, and the coarsely crushed coal particles enter the rotating cylinder 6 upward through each rectangular through hole 20, and the cutting blades 19 on each transverse cutting shaft 18 rotate to realize the second crushing of the coarsely crushed coal particles. After the secondary crushing, the secondary crushed coal particles become coal powder and enter the coal seam barrel 24 through the three fan-shaped through holes 36 and the coal seam through hole 4, and then enter the gasification chamber 21 through the coal seam barrel 24. At the same time, oxygen is transported downward from the ground through the oxygen delivery pipe 23. The oxygen enters each vertical oxygen dividing box 26 through the oxygen branch pipe 27. The oxygen in each vertical oxygen dividing box 26 then enters the gasification chamber 21 through each horizontal oxygen supply pipe 28. The oxygen is uniformly sprayed toward the center of the gasification chamber 21 through each nozzle 29, so that the oxygen and the coal powder in the gasification chamber 21 are fully contacted and mixed. The mixture of coal powder and oxygen in the gasification chamber 21 is ignited by each ignition electrode 30 to realize combustion and gasification of the coal powder. The synthesis gas generated after combustion is transported to the ground gas gathering station through the coalbed methane output pipe 22 for further processing;

[0051] Step (4) is specifically as follows: according to the method of drilling a horizontal well, after the new underground coal gasification mining system 53 is drilled along a certain horizontal direction of the coal seam 52 to the end of the coal seam 52, the multiple sections of the first pipe string 55, the second pipe string and the third pipe string are unhooked, so that the new underground coal gasification mining system 53 is gradually withdrawn to the coal seam 52 below the vertical borehole 54, and step (2) is repeated, so that the lower side of the first guide cylinder 1 is tilted in another direction, and drilling is continued, thereby changing the drilling direction again, so that the new underground coal gasification mining system 53 is drilled in the coal seam 52 along another horizontal direction, crushing the coal seam 52 into coal powder, and gasifying it again. After drilling through, it is withdrawn again and the drilling direction in the coal seam 52 is changed, and the coal is gasified. In this way, the operation is repeated, and all the coal seams 52 in the mining area can be gasified. The process of horizontal drilling and gasification in the coal seam 52 is the same as step (3) and will not be repeated.

[0052] The sealing housing, the gas sensor, the second pipe string and the third pipe string are not shown in the figure.

[0053] A platform for assembling and disassembling the first tubular string 55, the second tubular string and the third tubular string is provided on the ground (the method for assembling and disassembling the first tubular string 55, the second tubular string and the third tubular string is conventional in the art and will not be described in detail). Since the movement trajectory of the first tubular string 55, the second tubular string and the third tubular string synchronously turns from vertical to horizontal is an arc segment structure with an arc center angle of substantially 90°, the length of each section of the first tubular string 55, the second tubular string and the third tubular string is less than the arc length of the arc segment, such as Figure 10 shown.

[0054] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. An underground coal gasification drilling mining process, characterized by: The specific steps include: (1) At a pre-set construction site, the underground coal gasification mining system is operated to drill into the stratum vertically, breaking the stratum into soil debris and discharging it to the ground to form a vertical borehole; (2) When the underground coal gasification mining system drills down into the coal seam, the drilling direction is changed so that the underground coal gasification mining system drills in the coal seam in a horizontal direction to break the coal seam into coal powder; (3) The crushed coal powder is burned and gasified in the underground coal gasification mining system, and the synthesis gas generated after combustion is transported to the ground gas gathering station for further processing; (4) After the underground coal gasification mining system drills along the horizontal direction of the coal seam to the end of the coal seam, it is withdrawn to the coal seam below the vertical drill hole, and the drilling direction is changed, so that the underground coal gasification mining system drills along another horizontal direction in the coal seam to crush the coal seam into coal powder and gasify it again. After drilling through, it is withdrawn again and the drilling direction in the coal seam is changed to gasify it. In this way, the entire coal seam in the mining area can be gasified by repeating the operation; The underground coal gasification mining system includes a first guide cylinder, a second guide cylinder, a drilling and crushing device and a combustion gasification device. The first guide cylinder and the second guide cylinder are concentric and vertically arranged. The lower side of the first guide cylinder and the upper side and lower side of the second guide cylinder are open. The top of the first guide cylinder and the bottom of the second guide cylinder are fixedly connected. The drilling and crushing device is concentrically installed on the inner bottom of the first guide cylinder, and the combustion gasification device is concentrically fixedly installed in the second guide cylinder. A plurality of formation through holes in a circumferential array are provided on the top plate of the first guide cylinder. The first guide cylinder is connected to the annular cavity between the second guide cylinder and the combustion gasification device through each formation through hole. A coal seam through hole is provided in the center of the top plate of the first guide cylinder. The lower end of the combustion gasification device is fixedly connected to the coal seam through hole. A formation sealing device for sealing each formation through hole is provided in the first guide cylinder. A plurality of reducing and steering devices are provided on the outer circumference of the upper side of the second guide cylinder. The structures of the reducing and steering devices are the same and are arranged in a circumferential array.

2. The underground coal gasification drilling mining process according to claim 1, characterized in that: The first guide cylinder and the second guide cylinder are both stepped cylinder structures with a smaller upper portion and a larger lower portion. The outer diameter of the upper cylinder of the first guide cylinder is equal to the outer diameter of the lower cylinder of the second guide cylinder. Spiral ridges are evenly arranged on the outer circumference of the upper cylinder of the first guide cylinder. The drilling and crushing device includes a rotating cylinder and a driven internal gear. The rotating cylinder is coaxially arranged at the bottom of the lower cylinder of the first guide cylinder. The top of the rotating cylinder is open, and the outer circle of the rotating cylinder is in sliding contact with the inner circle of the lower cylinder of the first guide cylinder. A limiting ring groove is circumferentially provided on the middle part of the outer circle of the rotating cylinder. A plurality of limiting screws are threadedly connected on the outer circumference of the lower cylinder of the first guide cylinder. Each limiting screw is respectively arranged along the radial direction of the first guide cylinder. The inner end of each limiting screw passes through the lower cylinder wall of the first guide cylinder and extends into the limiting ring groove. The driven internal gear is coaxially arranged in the lower cylinder of the first guide cylinder and is located above the rotating cylinder. The inner diameter of the internal gear is the same as the inner diameter of the rotating cylinder, the outer diameter of the driven internal gear is not larger than the outer diameter of the rotating cylinder, the bottom of the driven internal gear and the top of the rotating cylinder are fixedly connected by a number of vertical connecting plates, and a number of motor fixing plates in a circumferential array are integrally formed on the lower side of the inner circle of the upper cylinder of the first guide cylinder. A rotary reduction motor is fixedly installed on each motor fixing plate, and the output shaft of each rotary reduction motor is vertically arranged. The output shaft of each rotary reduction motor passes downward through the motor fixing plate and extends into the interior of the driven internal gear, and the lower end of the output shaft of each rotary reduction motor is fixedly installed with a driving external gear that meshes with the driven internal gear for transmission. The lower surface of the bottom plate of the rotating cylinder is flush with the bottom of the lower cylinder of the first guide cylinder. A number of rigid ball protrusions are evenly arranged on the lower surface of the bottom plate of the rotating cylinder. A polygonal hollow prism is integrally formed in the middle of the upper surface of the bottom plate of the rotating cylinder. A number of vertical support plates are fixedly connected to the outer edge of the upper surface of the bottom plate of the rotating cylinder. Each vertical support plate is arranged in a circular array. Each vertical support plate is parallel to each side of the polygonal hollow prism. A horizontal crushing reduction motor is fixedly installed on the outer surface of each vertical support plate. The output shaft of each horizontal crushing reduction motor is arranged along the radial direction of the rotating cylinder. Each horizontal crushing reduction motor is respectively connected to the polygon The side faces of the hollow prism correspond one to one in the radial direction of the rotating cylinder, and the output shafts of the horizontal crushing reduction motors pass through the corresponding vertical support plates respectively. The output shafts of the horizontal crushing reduction motors are coaxially connected to a horizontal cutting shaft. The inner ends of the horizontal cutting shafts are rotatably mounted on the corresponding side faces of the polygonal hollow prism. Cutting blades are spirally arranged axially on the outer circumference of the horizontal cutting shafts. A number of rectangular through holes that are transparent from top to bottom and arranged in a circular array are provided on the bottom plate of the rotating cylinder. The length direction of the rectangular through holes is arranged along the radial direction of the rotating cylinder, and each rectangular through hole is located directly below each horizontal cutting shaft.

3. The underground coal gasification drilling mining process according to claim 2, characterized in that: The combustion gasification device includes a gasification chamber, a coalbed methane output pipe and an oxygen delivery pipe. The gasification chamber is a cylindrical structure that is transparent from top to bottom. The gasification chamber is vertically arranged inside the lower tube of the second guide tube with the same center. The lower end of the gasification chamber is fixedly connected to the coal seam tube. The lower end of the coal seam tube is fixedly connected to the coal seam through hole. The coalbed methane output pipe is arranged inside the upper tube of the second guide tube with the same center. The lower end of the coalbed methane output pipe is fixedly connected to the upper end of the gasification chamber. The oxygen delivery pipe is fixedly sleeved on the outer circumference of the coalbed methane output pipe with the same center. An oxygen supply annular cavity is formed between the inner circle of the oxygen delivery pipe and the outer circle of the coalbed methane output pipe. The lower end of the oxygen delivery pipe is fixedly connected to an annular sealing plate sleeved on the coalbed methane output pipe. The inner circle of the annular sealing plate is fixedly connected to the outer circle of the coalbed methane output pipe. A plurality of vertical oxygen dividing boxes are arranged in a circumferential array inside the lower tube of the second guide tube. The gasification chamber is located in the middle of each of the dry vertical oxygen dividing boxes. The outer circumference of the lower side of the oxygen delivery pipe is fixedly connected There are several oxygen branch pipes in a circular array, and the lower end of each oxygen branch pipe is fixedly connected to the top of each vertical oxygen dividing box. Each vertical oxygen dividing box is fixedly connected to the gasification chamber through several horizontal oxygen supply pipes arranged up and down. The inner end of each horizontal oxygen supply pipe passes through the wall of the gasification chamber and extends into the gasification chamber. The inner end of each horizontal oxygen supply pipe is fixedly installed with a nozzle that sprays toward the center of the gasification chamber. Several ignition electrodes in a circular array are fixedly arranged on the lower inner wall of the gasification chamber. The inner lower part of the coal seam barrel is rotatably connected to a disc-shaped coal seam channel plugging plate. The left and right sides of the circular circumference of the disc-shaped coal seam channel plugging plate are fixedly connected to a rotating shaft rotatably set on the wall of the coal seam barrel. Two coal seam channel servos are fixedly installed on the outer circumference of the lower side of the coal seam barrel. The two coal seam channel servos are symmetrically arranged on both sides of the coal seam barrel. The output shafts of the two coal seam channel servos are synchronously driven and connected to the left and right rotating shafts respectively.

4. The underground coal gasification drilling mining process according to claim 3, characterized in that: The stratum sealing device includes a hydraulic cylinder and a stratum sealing plate. The hydraulic cylinder is vertically arranged in the lower tube of the first guide tube with the same center. The outer circumference of the top of the polygonal hollow prism is fixedly connected to the first fixed seat through a number of support rods. The hydraulic cylinder is fixedly installed on the first fixed seat. The stratum sealing plate is a disc-shaped plate. The stratum sealing plate is horizontally arranged in the upper tube of the first guide tube with the same center. The piston rod of the hydraulic cylinder extends vertically upward. The bottom center of the stratum sealing plate is fixedly connected to the upper end of the piston rod of the hydraulic cylinder. Three fan-shaped through holes are evenly opened on the stratum sealing plate. The three fan-shaped through holes are arranged in a circular array. The diameter of the stratum sealing plate is larger than the diameter of the circle where the outermost quadrant points of each stratum through hole are located and smaller than the inner diameter of the upper tube of the first guide tube. The outer arc diameter of the fan-shaped through hole is equal to the diameter of the circle where the innermost quadrant points of each stratum through hole are located, and the inner arc diameter of the fan-shaped through hole is smaller than the diameter of the coal seam through hole.

5. The underground coal gasification drilling mining process according to claim 4, characterized in that: The variable diameter steering device includes a second fixed seat, a guide reduction motor, two guide light bars, a guide screw, a screw nut, a slider, an L-shaped guide plate, a hinged support and a variable diameter moving block. The upper side and lower side of the outer circumference of the upper cylinder of the second guide cylinder are fixedly connected with an annular flange. The second fixed seat is fixedly connected to the lower side of the upper annular flange. The guide reduction motor, the guide screw and the two guide light bars are all vertically arranged. The guide reduction motor is fixedly installed on the second fixed seat. The L-shaped guide plate includes a horizontal plate and a vertical plate. The horizontal plate The front side of the guide is fixedly connected to the upper side of the vertical plate as a whole, the lower end of the output shaft of the guide reduction motor is transmission-connected to the upper end of the guide screw, and the lower end of the guide screw is rotatably connected to the horizontal plate of the L-shaped guide plate. The two guide light bars are symmetrically arranged on both sides of the guide reduction motor, and the upper ends of the two guide light bars are fixedly connected to the upper annular flange, and the lower ends of the two guide light bars are fixedly connected to the lower annular flange. The left and right sides of the vertical plate of the L-shaped guide plate are respectively fixedly connected to the two guide light bars and are located on the two guide light bars. The two guide light bars pass through the left and right sides of the slider respectively. The slider is slidably connected to the two guide light bars. The screw nut is sleeved on the guide screw and is threadedly connected to the guide screw. The front side of the screw nut is fixedly connected to the middle of the slider by a screw. The hinged support is fixedly installed on the upper side of the annular flange on the lower side by screws and is located between the two guide light bars. The lower ends of the two guide light bars pass through the left and right sides of the hinged support respectively. The diameter-changing moving block is set in front of the vertical plate of the L-shaped guide plate. The diameter-changing moving block A horizontal limit rod is fixedly connected to the middle part of the rear side of the block, and a vertical guide long hole that is transparent from front to back is opened on the vertical plate of the L-shaped guide plate. The rear side of the horizontal limit rod passes through the vertical guide long hole, and the upper and lower sides of the variable diameter moving block are hinged with a connecting rod. The upper end of the upper connecting rod is hinged to the lower side of the slider, and the lower end of the lower connecting rod is hinged to the hinged support. A guide skin is fixedly installed between the two annular flanges and is mounted on the outside of the upper tube of the second guide tube. The outer side surface of the variable diameter moving block presses against the inner side surface of the guide skin.

6. The underground coal gasification drilling mining process according to claim 5, characterized in that: A sealing cover is provided on the outside of the driven internal gear and each driving external gear, and a gas sensor is provided on the inner wall of the first guide cylinder.

7. The underground coal gasification drilling mining process according to claim 6, characterized in that: The upper end of the second guide cylinder is fixedly connected to several sections of the first pipe string, the upper end of the oxygen delivery pipe is fixedly connected to several sections of the second pipe string, and the upper end of the coalbed methane output pipe is fixedly connected to several sections of the third pipe string. The first pipe string is concentrically sleeved on the outside of the second pipe string, and the second pipe string is concentrically sleeved on the outside of the third pipe string. Radial support ribs are arranged between the outer circle of the third pipe string and the inner circle of the second pipe string, and between the outer circle of the second pipe string and the inner circle of the first pipe string. The upper ends of the first pipe string, the second pipe string and the third pipe string are all provided with internal threaded female heads, and the lower ends of the first pipe string, the second pipe string and the third pipe string are all provided with external threaded male heads. Two adjacent sections of the first pipe string, two adjacent sections of the second pipe string and two adjacent sections of the third pipe string are all fixedly connected and sealed by internal threaded female heads and external threaded male heads.

8. The underground coal gasification drilling mining process according to claim 7, characterized in that: Step (1) is specifically as follows: first, the underground coal gasification mining system is vertically set, the bottom of the rotating cylinder contacts the ground, the two coal seam channel servos drive the two rotating shafts to rotate the disc-shaped coal seam channel plug to a horizontal state, the disc-shaped coal seam channel plug seals the coal seam cylinder, the piston rod of the hydraulic cylinder is in a retracted state, so that the formation plug is separated from the inner surface of the top plate of the first guide cylinder and has a large distance, each formation through hole is in a transparent state, the first guide cylinder is connected to the annular cavity between the second guide cylinder and the combustion gasification device through each formation through hole, then, each rotating reduction motor is started synchronously, the output shaft of each rotating reduction motor drives each active external gear to rotate synchronously, each active external gear synchronously drives the driven internal gear to rotate, the driven internal gear drives the rotating cylinder to rotate synchronously, each rigid ball protrusion on the lower surface of the bottom plate of the rotating cylinder coarsely crushes the formation, and the coarsely crushed soil particles enter the rotating cylinder upward through each rectangular through hole, in this process, each transverse crushing reduction motor rotates synchronously and drives each transverse cutting shaft, each transverse cutting shaft The cutting blades on the upper part rotate and realize secondary crushing of the coarsely crushed soil particles. The upper port of the annular cavity between the first pipe string and the second pipe string is connected to the exhaust port of the exhaust fan on the ground. The exhaust fan is started to draw the secondary crushed soil particles into the annular cavity between the second guide cylinder and the combustion gasification device through the through holes of each formation, and then draw them upward to the ground through the annular cavity between the second guide cylinder and the gasification chamber, the coalbed methane output pipe and the oxygen delivery pipe, and the annular cavity between the first pipe string and the second pipe string. The outer circumference of the upper side of the first guide cylinder is The spiral ridges cut the inner wall of the vertical borehole, so that the outer circle of the first guide cylinder and the inner wall of the vertical borehole form an annular cavity for ventilation. It can also reduce the contact area between the outer circumference of the first guide cylinder and the inner wall of the vertical borehole, and reduce the friction resistance during the drilling process. The drilling process is achieved by connecting a single first pipe string, a second pipe string and a third pipe string to the upper end of the second guide cylinder, the upper end of the oxygen delivery pipe and the upper end of the coalbed methane output pipe, respectively, and simultaneously buckling and continuously connecting multiple sections of the first pipe string, the second pipe string and the third pipe string to advance forward.

9. The underground coal gasification drilling mining process according to claim 8, characterized in that: Step (2) is specifically as follows: when the gas sensor detects gas, it indicates that the bottom of the rotating cylinder has drilled into the coal seam, then the vertical drilling is changed to horizontal drilling, and the guide reduction motors on the side of the outer circumference of the upper cylinder of the second guide cylinder are controlled to move forward, and the guide reduction motors on the side of the outer circumference of the upper cylinder of the second guide cylinder synchronously drive the corresponding guide screws to rotate forward, driving the corresponding screw nuts to drive the corresponding sliders to move downward, so that the corresponding variable-diameter moving blocks are all extended outward to press the guide skin and act on the well wall, and the corresponding variable-diameter moving blocks can act in the opposite direction on the side of the outer circumference of the upper cylinder of the second guide cylinder under the action of the well wall. When the cam is in the air, the guide shaft is moved in an opposite direction so that the cam can move ...

10. The underground coal gasification drilling mining process according to claim 9, characterized in that: Step (3) is specifically as follows: when drilling into the coal seam and the drilling direction becomes horizontal, the two coal seam channel servos drive the two rotating shafts to rotate the disc-shaped coal seam channel plugging plate to a vertical state, then the channel of the coal seam barrel is opened, and the piston rod of the hydraulic cylinder extends upward, so that the formation plugging plate moves upward until it is in tight contact with the inner surface of the top plate of the first guide barrel, and each formation through hole is blocked. The first guide barrel is connected to the coal seam barrel through the coal seam through hole, and then the first guide barrel is connected to the gasification chamber. The rigid ball protrusions on the lower surface of the bottom plate of the rotating barrel coarsely crush the coal seam, and the coarsely crushed coal particles enter the rotating barrel upward through each rectangular through hole, and the cutting blades on each transverse cutting shaft rotate to realize the second crushing of the coarsely crushed coal particles. The coal particles are crushed once, and the secondary crushed coal particles become coal powder and enter the coal seam barrel through three fan-shaped through holes and the coal seam through hole, and then enter the gasification chamber through the coal seam barrel. At the same time, oxygen is transported downward from the ground through the oxygen delivery pipe, and the oxygen enters each vertical oxygen dividing box through the oxygen branch pipe. The oxygen in each vertical oxygen dividing box then enters the gasification chamber through each horizontal oxygen supply pipe. The oxygen is evenly sprayed toward the center of the gasification chamber through each nozzle, so that the oxygen and the coal powder in the gasification chamber are fully contacted and mixed. The mixture of coal powder and oxygen in the gasification chamber is ignited by each ignition electrode to realize the combustion and gasification of the coal powder. The synthesis gas generated after combustion is transported to the ground gas gathering station through the coalbed methane output pipe for further processing; Step (4) is specifically as follows: according to the method of drilling a horizontal well, after the underground coal gasification mining system is drilled along a certain horizontal direction of the coal seam to the end of the coal seam, the multiple sections of the first pipe string, the second pipe string and the third pipe string are unhooked, so that the underground coal gasification mining system is gradually withdrawn to the coal seam below the vertical borehole, and step (2) is repeated, so that the lower side of the first guide cylinder is tilted in another direction, and drilling is continued, thereby changing the drilling direction again, so that the underground coal gasification mining system is drilled in the coal seam along another horizontal direction, the coal seam is crushed into coal powder, and gasified again. After drilling through, the system is withdrawn again and the drilling direction in the coal seam is changed, and gasification is carried out. In this way, the operation is repeated, and all the coal seams in the mining area can be gasified. The process of horizontal drilling and gasification in the coal seam is the same as step (3).

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