Anti-blocking gasification furnace for underground coal gasification and operation method

Abstract

The invention relates to the technical field of underground coal gasification, in particular to an anti-blocking gasification furnace for underground coal gasification and an operation method of the anti-blocking gasification furnace for underground coal gasification. Comprising an overlying rock layer, a coal seam body, a horizontal injection well, a horizontal section, a branch type product well, a branch point, a horizontal well branch, a downward well branch and a communication point, the coal seam body is arranged on the bottom face of the overlying rock layer, the horizontal injection well is arranged on the inner side of the overlying rock layer, and the horizontal section is arranged at the bottom end of the horizontal injection well; a branch type product well is arranged on the inner side of the overlying rock layer, a branch point is arranged at the bottom end of the branch type product well, a downward well branch is arranged on the bottom face of the branch point, and a horizontal well branch is arranged on one side of the branch point. Through a branch gas transmission mode, after an overlying rock layer collapses, a horizontal branch gas transmission channel of the branch product well is opened in time, so that the product well can normally produce synthesis gas, channel blockage is avoided, and the service life of the gasification furnace is effectively prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of underground coal gasification, and in particular to an anti-blocking gasification furnace for underground coal gasification and an operating method. Background Art

[0002] Underground coal gasification (ISC) is a process that converts coal directly into a product gas, commonly called syngas, by combustion and gasification reactions in underground coal seams in the presence of an oxidant. The syngas can then be used as a feedstock for a variety of applications, including fuel production, chemical production, and power generation.

[0003] After the current underground gasifier is ignited and gasification production begins, the furnace cavity of the gasifier continues to develop, causing the overlying rock strata to collapse under the action of stratum stress. The rock cuttings that fall from the collapse may cause the directional product well synthesis gas transportation channel to be blocked, causing the gasifier to be blocked and scrapped, affecting the service life of the gasifier.

[0004] Therefore, in view of the fact that existing underground gasifiers are more likely to cause blockage of gas transmission channels due to rock collapse, a blockage-resistant gasifier for underground coal gasification can be designed. Through branched gas transmission, after the overlying rock collapses, the horizontal branch gas transmission channels of the branched product wells can be opened in time to enable the product wells to produce synthesis gas normally, avoid channel blockage, and effectively extend the service life of the gasifier. Summary of the invention

[0005] The present invention is proposed to overcome the problem that after most underground gasifiers are ignited and gasification production begins, the collapsed rock debris may cause the directional product well synthesis gas transportation channel to be blocked, resulting in the blockage and scrapping of the gasifier.

[0006] The technical solution of the present invention is: a blockage-proof gasifier for underground coal gasification, including an overlying rock layer, a coal seam body, a horizontal injection well, a gasifier furnace cavity, a horizontal section, a branched product well, a ventilation component, a branch point, a horizontal well branch, a downward well branch and a connecting point. The coal seam body is arranged on the bottom surface of the overlying rock layer, the horizontal injection well is arranged on the inner side of the overlying rock layer, the horizontal section is arranged on the bottom end of the horizontal injection well, the branched product well is arranged on the inner side of the overlying rock layer, the ventilation component is arranged on the inner side of the horizontal injection well and the branched product well, the branch point is arranged on the bottom end of the branched product well, the downward well branch is arranged on the bottom surface of the branch point, the horizontal well branch is arranged on one side of the branch point, the connecting point is arranged at one end of the downward well branch, the horizontal section is connected with the branched product well at the connecting point, and the gasifier furnace cavity is arranged on the outer side of the horizontal section and the horizontal well branch.

[0007] Preferably, a fixed ventilation assembly is set for the horizontal injection well and the branch product well, and the ventilation assembly is used to fix the oxidant injection equipment and the ignition equipment, and the oxidant is injected into the horizontal injection well, so that the oxidant enters the gasifier furnace chamber through the horizontal section, so that the coal seam body in the gasifier furnace chamber undergoes a gasification reaction, and the gas generated by the reaction enters the downward well branch through the connection point, and the gas is transmitted to the branch product well by the downward well branch, and the gas is transported to the ground through the branch product well for unified collection and storage. As the gasification reaction proceeds, the furnace area of ​​the gasifier continues to expand. At this time, the ground stress of the overlying strata changes, and the rock debris of the collapsed overlying strata causes the gas passages of the downward well branch and the branch product well to be blocked, and the collapse of the overlying strata causes the destruction of the horizontal well branch, so that the branch product well and the horizontal well branch are connected through the branch point, and a second channel is provided for the transportation of synthesis gas through the horizontal well branch, so that the horizontal branch gas transmission channel of the branch product well is opened in time, so that the product well can produce synthesis gas normally, avoid the effect of channel blockage, and extend the service life of the gasifier.

[0008] Preferably, the horizontal injection well penetrates the overlying rock formation, and the other end of the horizontal injection well extends to the bottom of the main body of the coal seam, and the horizontal section is parallel to the bottom plate of the main body of the coal seam.

[0009] Preferably, the branch production well penetrates the overlying rock formation, and a horizontal well branch is arranged at one end of the branch production well, and the horizontal well branch is arranged horizontally in the main body of the coal seam.

[0010] Preferably, the horizontal well branch and the downward well branch can be set as a horizontal well and a vertical well branch, or as a horizontal well and a deviated well branch, or as a horizontal well and a directional well branch.

[0011] Preferably, the horizontal section is 0.5 to 1 meter away from the bottom plate of the coal seam, the horizontal well branch is -1 to +1 meter away from the main roof of the coal seam, and the bottom end of the downward well branch is 0.5 to 1 meter away from the main bottom plate of the coal seam.

[0012] Preferably, the length of the horizontal section is set to 500-1500 meters, the length of the horizontal well branch is set to 50 meters to 1500 meters, and the horizontal projection displacement deviation between the horizontal well branch and the horizontal section is 0 meters to 10 meters.

[0013] Preferably, the ventilation assembly includes an injection well casing, a product well casing and openings. The injection well casing is arranged on the inner side of the horizontal injection well, and the product well casing is arranged on the inner side of the branch product well. An opening is arranged at one end of the injection well casing, and an opening is arranged at one end of the product well casing. There are multiple groups of openings, and the opening diameters are 5 to 35 mm. The openings are staggered and spaced, and the total area of ​​the openings accounts for 5% to 35% of the area of ​​the injection well casing and the product well casing.

[0014] An operating method of a blocking-proof gasifier for underground coal gasification, using the blocking-proof gasifier for underground coal gasification as described above, comprises the following steps:

[0015] Step 100, fix the injection well casing in the horizontal injection well, then place the oxidant injection equipment and the ignition equipment in the injection well casing, and then inject the oxidant into the horizontal injection well, so that the oxidant leaks out from the opening, flows through the horizontal section and enters the gasifier furnace cavity, so that the coal seam body in the gasifier furnace cavity undergoes a gasification reaction;

[0016] Step 200: After the gasification reaction starts, the gas generated by the reaction enters the downward well branch through the connection point, and the downward well branch transmits the gas to the branch product well. The synthetic gas enters the product well casing in the branch product well through the opening, and then the product well casing is used to transport the gas to the ground for unified collection and storage;

[0017] Step 300: When the furnace area of ​​the gasifier continues to expand and causes the overlying rock formation to collapse, the rock debris generated by the collapse of the overlying rock formation blocks the gas passages to the downhole branch and the branch product well, and enables the branch product well to establish a connection with the horizontal well branch through the branch point, thereby providing a second channel for the transportation of synthesis gas through the horizontal well branch.

[0018] Beneficial effects of the present invention:

[0019] During the gasification reaction, the oxidant injection equipment and ignition equipment are fixed through the horizontal injection well, and the oxidant is injected into the horizontal injection well, so that the oxidant enters the gasifier furnace cavity through the horizontal section. After ignition, the coal seam body in the gasifier furnace cavity undergoes a gasification reaction, and the synthesis gas produced by the reaction enters the downward well branch through the connecting point. The synthesis gas is transmitted to the branch product well by the downward well branch, and the synthesis gas is transported to the ground through the branch product well for unified collection and storage. As the gasification reaction proceeds, the gasifier furnace cavity area continues to expand, and at this time, the ground stress of the overlying rock stratum occurs. The rock debris from the collapse of the overlying strata causes the gas passages to the downward well branches and the branched product wells to be blocked. At the same time, the collapse of the overlying strata causes the destruction of the horizontal well branches, so that the branched product wells are connected with the horizontal well branches through the branch points, and a second channel is provided for the transportation of synthesis gas through the horizontal well branches. This solves the problem that after the gasifier is ignited and gasification production begins in most underground gasifiers, the rock debris dropped by the collapse of the overlying strata may cause the synthesis gas transportation channel of the directional product well to be blocked, causing the gasifier to be blocked and scrapped, thereby extending the service life of the gasifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is a schematic diagram of the three-dimensional structure of a blocking-proof gasifier for underground coal gasification according to the present invention;

[0021] Figure 2Shown is a schematic diagram of the three-dimensional structure of branch points and connecting points of a gasifier for preventing blockage in underground coal gasification according to the present invention;

[0022] Figure 3 Shown is a schematic diagram of a cross-sectional three-dimensional structure of a blocking-proof gasifier for underground coal gasification according to the present invention;

[0023] Figure 4 Shown is a schematic diagram of the three-dimensional structure of a product well casing of an anti-blocking gasification furnace for underground coal gasification of the present invention.

[0024] Explanation of the accompanying reference numerals: 1. overlying rock strata; 2. main body of the coal seam; 3. horizontal injection well; 301. injection well casing; 4. horizontal section; 5. branched product well; 501. product well casing; 502. opening; 6. branching point; 7. horizontal well branch; 8. downward well branch; 9. connecting point; 10. gasifier furnace chamber. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] See also Figure 1 and Figure 2The present invention provides an embodiment: a blocking-proof gasifier for underground coal gasification, comprising an overlying rock stratum 1, a coal seam body 2, a horizontal injection well 3, a gasifier furnace chamber 10, a horizontal section 4, a branch product well 5, a ventilation component, a branch point 6, a horizontal well branch 7, a downward well branch 8 and a connecting point 9. The coal seam body 2 is arranged on the bottom surface of the overlying rock stratum 1, and a horizontal injection well 3 is arranged on the inner side of the overlying rock stratum 1. The horizontal injection well 3 runs through the overlying rock stratum 1, and the other end of the horizontal injection well 3 extends to the bottom of the coal seam body 2. A horizontal section 4 is arranged at the bottom end of the horizontal injection well 3, and the horizontal section 4 is parallel to the bottom plate of the coal seam body 2. The horizontal section 4 is 0.5 to 1 meter away from the bottom plate of the coal seam, and the length of the horizontal section 4 is set to 500-1500 meters. A branch product well 5 is arranged on the inner side of the overlying rock stratum 1, and the branch product well 5 runs through the overlying rock stratum 1. Ventilation components are arranged on the inner sides of the horizontal injection well 3 and the branch product well 5. A branch point 6 is provided at the bottom end of the branch product well 5, and a horizontal well branch 7 is provided on one side of the branch point 6. A horizontal well branch 7 is provided at one end of the branch product well 5. The horizontal well branch 7 is horizontally arranged in the coal seam main body 2, and the horizontal well branch 7 is -1 to +1 meter away from the top plate of the coal seam main body 2. The length of the horizontal well branch 7 is set to 50 meters to 1500 meters. The horizontal projection displacement deviation between the horizontal well branch 7 and the horizontal section 4 is 0 meters to 10 meters. A downward well branch 8 is provided on the bottom surface of the branch point 6. The horizontal well branch 7 and the downward well branch 8 can be set as horizontal well and vertical well branches, or as horizontal well and inclined well branches, or as horizontal well directional well branches. The bottom end of the downward well branch 8 is 0.5 meters to 1 meter away from the bottom plate of the coal seam main body 2. A connecting point 9 is provided at one end of the downward well branch 8. The horizontal section 4 is connected with the branch product well 5 at the connecting point 9, and a gasifier furnace chamber 10 is provided on the outside of the horizontal section 4 and the horizontal well branch 7.

[0027] See also Figure 3 and Figure 4 In this embodiment, the ventilation component includes an injection well casing 301, a product well casing 501 and an opening 502. The injection well casing 301 is arranged on the inner side of the horizontal injection well 3, and the product well casing 501 is arranged on the inner side of the branch product well 5. An opening 502 is opened at one end of the injection well casing 301, and an opening 502 is opened at one end of the product well casing 501. There are multiple groups of openings 502, and the aperture of the openings 502 is 5 to 35 mm. The openings 502 are staggered and distributed at intervals. The total area of ​​the openings 502 accounts for 5% to 35% of the area of ​​the injection well casing 301 and the product well casing 501. The oxidant injection device and the ignition device are fixed through the injection well casing 301, and the oxidant is injected into the gasifier furnace chamber 10 with the help of the opening 502. The synthesis gas enters the product well casing 501 through the opening 502, and the product well casing 501 is used to define the synthesis gas transmission channel, and the synthesis gas is transported to the ground for unified collection and storage.

[0028] Before the reaction, the injection well casing 301 is fixed in the horizontal injection well 3, and then the oxidant injection equipment and the ignition equipment are placed in the injection well casing 301, and the oxidant is injected into the horizontal injection well 3, so that the oxidant leaks out from the opening 502 and enters the gasifier furnace chamber 10 through the horizontal section 4, so that the coal seam main body 2 in the gasifier furnace chamber 10 undergoes a gasification reaction, and the gas generated by the reaction enters the downward well branch 8 through the connecting point 9, and the downward well branch 8 transmits the gas to the branch product well 5, and the synthetic gas enters the product well casing 501 in the branch product well 5 through the opening 502, and the product well casing 501 is used to transport the gas to the ground for unified collection and storage;

[0029] As the gasification reaction proceeds, the area of ​​the gasifier furnace chamber 10 continues to expand. At this time, the ground stress of the overlying rock stratum 1 changes. The rock debris from the collapse of the overlying rock stratum 1 causes the gas passages to the downhole branch 8 and the branch product well 5 to be blocked. The collapse of the overlying rock stratum 1 causes the destruction of the horizontal well branch 7, thereby establishing a connection between the branch product well 5 and the horizontal well branch 7 through the branch point 6, providing a second channel for the transportation of synthesis gas through the horizontal well branch 7, thereby ensuring the normal transportation of synthesis gas.

[0030] Through the above steps, by setting the horizontal injection well 3 and the branch product well 5 to fix the ventilation assembly, the ventilation assembly is used to fix the oxidant injection equipment and the ignition equipment, the oxidant is injected into the horizontal injection well 3, and the oxidant enters the gasifier furnace chamber 10 through the horizontal section 4, so that the coal seam main body 2 in the gasifier furnace chamber 10 undergoes a gasification reaction, and the gas generated by the reaction enters the downward well branch 8 through the connecting point 9, and the gas is transmitted to the branch product well 5 by the downward well branch 8, and the gas is transported to the ground through the branch product well 5 for unified collection and storage. As the reaction proceeds, the area of ​​the gasifier chamber 10 continues to expand. At this time, the ground stress of the overlying stratum 1 changes. The rock debris from the collapse of the overlying stratum 1 causes blockage of the gas passages to the downhole branch 8 and the branch product well 5. The collapse of the overlying stratum 1 causes the destruction of the horizontal well branch 7, so that the branch product well 5 is connected to the horizontal well branch 7 through the branch point 6. The second channel is provided for the transportation of the synthesis gas through the horizontal well branch 7, thereby timely opening the horizontal branch gas transmission channel of the branch product well, so that the product well can produce synthesis gas normally and avoid channel blockage.

[0031] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the spirit of the present invention.

Claims

1. A gasifier for underground coal gasification with an anti-blocking function, comprising an overlying rock layer (1), a coal seam body (2), a horizontal injection well (3), and a gasifier chamber (10), characterized in that: The invention also comprises a horizontal section (4), a branch product well (5), a ventilation assembly, a branch point (6), a horizontal well branch (7), a downward well branch (8) and a connecting point (9); a coal seam main body (2) is arranged on the bottom surface of the overlying rock formation (1); a horizontal injection well (3) is arranged on the inner side of the overlying rock formation (1); a horizontal section (4) is arranged at the bottom end of the horizontal injection well (3); a branch product well (5) is arranged on the inner side of the overlying rock formation (1); the horizontal injection well (3) and the branch product well (5) are arranged on the inner side of the overlying rock formation (1); A ventilation assembly is arranged on the inner side of the product well (5); a branch point (6) is arranged at the bottom end of the branch product well (5); a downward well branch (8) is arranged on the bottom surface of the branch point (6); a horizontal well branch (7) is arranged on one side of the branch point (6); a connecting point (9) is arranged at one end of the downward well branch (8); the horizontal section (4) is connected to the branch product well (5) at the connecting point (9); and a gasification furnace chamber (10) is arranged on the outer side of the horizontal section (4) and the horizontal well branch (7).

2. The anti-blocking gasifier for underground coal gasification according to claim 1, characterized in that: The horizontal injection well (3) penetrates the overlying rock layer (1), the other end of the horizontal injection well (3) extends to the bottom of the coal seam body (2), and the horizontal section (4) is parallel to the bottom plate of the coal seam body (2).

3. The anti-blocking gasifier for underground coal gasification according to claim 1, characterized in that: The branch production well (5) penetrates the overlying rock layer (1), and a horizontal well branch (7) is arranged at one end of the branch production well (5), and the horizontal well branch (7) is arranged horizontally in the main body of the coal seam (2).

4. The anti-blocking gasifier for underground coal gasification according to claim 3, characterized in that: The horizontal well branch (7) and the downward well branch (8) can be set as a horizontal well and a vertical well branch, or as a horizontal well and an inclined well branch, or as a horizontal well and a directional well branch.

5. The anti-blocking gasifier for underground coal gasification according to claim 1, characterized in that: The horizontal section (4) is 0.5 to 1 meter away from the bottom plate of the coal seam, the horizontal well branch (7) is -1 to +1 meter away from the top plate of the main coal seam (2), and the bottom end of the downward well branch (8) is 0.5 to 1 meter away from the bottom plate of the main coal seam (2).

6. The anti-blocking gasifier for underground coal gasification according to claim 5, characterized in that: The length of the horizontal section (4) is set to 500-1500 meters, the length of the horizontal well branch (7) is set to 50 meters to 1500 meters, and the horizontal projection displacement deviation between the horizontal well branch (7) and the horizontal section (4) is 0 meters to 10 meters.

7. The anti-blocking gasifier for underground coal gasification according to claim 1, characterized in that: The ventilation component comprises an injection well casing (301), a product well casing (501) and openings (502). The injection well casing (301) is arranged on the inner side of the horizontal injection well (3), and the product well casing (501) is arranged on the inner side of the branch product well (5). One end of the injection well casing (301) is provided with an opening (502), and one end of the product well casing (501) is provided with an opening (502). There are multiple groups of openings (502), and the aperture of the openings (502) is 5 to 35 mm. The openings (502) are arranged at staggered intervals, and the total area of ​​the openings (502) accounts for 5% to 35% of the area of ​​the injection well casing (301) and the product well casing (501).

8. An operating method for an anti-blocking gasifier for underground coal gasification, characterized in that: The anti-blocking gasifier for underground coal gasification according to any one of claims 1 to 7 comprises the following steps: Step 100, fix the injection well casing (301) in the horizontal injection well (3), then place the oxidant injection equipment and the ignition equipment in the injection well casing (301), and then inject the oxidant into the horizontal injection well (3), so that the oxidant leaks out from the opening (502), flows through the horizontal section (4) and enters the gasifier furnace chamber (10), so that the coal seam body (2) in the gasifier furnace chamber (10) undergoes a gasification reaction; Step 200, after the gasification reaction starts, the gas generated by the reaction enters the downward well branch (8) through the connecting point (9), and the downward well branch (8) transmits the gas to the branch product well (5), and the synthesis gas enters the product well casing (501) in the branch product well (5) through the opening (502), and then the product well casing (501) is used to transport the gas to the ground for unified collection and storage; Step 300: When the area of ​​the gasifier chamber (10) continues to expand and causes the overlying rock formation (1) to collapse, the rock debris generated by the collapse of the overlying rock formation (1) blocks the gas passages to the downhole branch (8) and the branch product well (5), and enables the branch product well (5) to establish communication with the horizontal well branch (7) through the branch point (6), thereby providing a second passage for the transportation of synthesis gas through the horizontal well branch (7).

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