Raw material injection system for underground coal gasification process

Abstract

The utility model relates to a raw material injection system for a coal underground gasification process. The raw material injection system comprises an oxidizing agent conveying mechanism, a gasifying agent injection mechanism, an injection well and an underground gasification furnace, the oxidizing agent conveying mechanism comprises an oxidizing agent conveying pipeline, and the gasifying agent injection mechanism comprises a gasifying agent injection main pipeline. A first pressure transmitter, an emergency cut-off valve, an inert protective gas mechanism, a second pressure transmitter, a first flow meter and a second check valve are sequentially connected to each of the oxidant conveying pipeline and the gasifying agent injection main pipeline from one side of the gas inlet port; the raw material injection system provides multiple channels for raw material injection, gasification reaction is more complete, the phenomenon that underground synthesis gas flows into an oxidizing agent conveying pipeline or a gasifying agent injection pipeline due to the fact that a check valve cannot be sealed or a sealing surface is damaged can be prevented, and the inert protective gas mechanism is interlocked through differential pressure, so that the process operation safety is guaranteed; during shutdown maintenance, the system can also be used for pipeline purging.

Description

Technical Field

[0001] The utility model belongs to the technical field of underground coal gasification process, and particularly relates to a raw material injection system for an underground coal gasification process. Background Art

[0002] Underground coal gasification (ISC) is a process of directly converting coal into product gas through the combustion and gasification reactions of underground coal seams in the presence of an oxidant. The product gas is usually called syngas, which can then be used as a raw material for various applications, including fuel production, chemical production, and power generation. This underground coal gasification technology is applicable to most coal reserves. Given the increasingly strict environmental protection requirements in the mining industry and considering the related labor costs and infrastructure costs, this technology is undoubtedly very attractive. The coal gasification process is a process of converting coal into syngas through a series of chemical reactions.

[0003] Surface drilling penetrates directly into the coal seam, providing an effective channel for oxidant injection and product gas production. A pair of drillings are connected underground or horizontally extended to form a substantially horizontal drilling channel (which can also be simply referred to as a coal seam wellbore or a communication channel). This channel helps oxidant injection, the growth of the combustion void area, and product gas transportation. A drilling for oxidant injection is called an "injection well", and another drilling for producing product gas is called a "product well".

[0004] When there are an injection well, a product well, and a horizontal channel connecting the two in the coal seam, this structure is called an underground coal gasification (ISC) unit or well pair. The ISC unit includes a combustion zone, a gasification zone, and a pyrolysis zone. Among them, the combustion zone is near the oxidant injection point in the coal seam; the gasification zone surrounds the combustion zone in a radial shape or is downstream of the combustion zone, where coal is gasified and partially oxidized to generate product gas; the pyrolysis zone is downstream of the gasification zone, and the pyrolysis reaction of coal generally occurs here. The high-temperature product gas flows downstream from the gasification zone and is finally transported to the ground from the wellhead of the product well. While the coal is burning or gasifying, the ISC combustion void area in the coal seam will grow and expand.

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

[0006] During the process of underground coal gasification, the internal environment of the pipeline system is at high temperature and high pressure, which may cause the check valve to fail to seal or the sealing surface to be damaged, resulting in the underground syngas leaking into the oxidant or gasifying agent conveying pipeline. The media such as CO, CO2, H2, CH4, and H2S in the syngas produced by the underground gasifier are all flammable and explosive substances. They can form explosive mixtures when mixed with air and can cause combustion and explosion accidents when encountering open flames or high heat. Therefore, a device needs to be set up to solve this problem. Summary of the Utility Model

[0007] The purpose of the present utility model is to provide a raw material injection system with a simple structure and reasonable design in order to solve the above problems.

[0008] The present utility model realizes the above purpose through the following technical solutions:

[0009] A raw material injection system for underground coal gasification process, including an oxidant conveying mechanism, a gasifying agent injection mechanism, an injection well, and an underground gasifier;

[0010] The oxidant conveying mechanism includes an oxidant conveying pipeline. The gasifying agent injection mechanism includes a main gasifying agent injection pipeline. On the oxidant conveying pipeline and the main gasifying agent injection pipeline, starting from the intake port side, a first pressure transmitter, an emergency cut-off valve, an inert protection gas mechanism, a second pressure transmitter, a first flowmeter, and a second check valve are successively connected. A bypass valve group is arranged on one side of the emergency cut-off valve;

[0011] The inert protection gas mechanisms each include a main inert protection gas conveying pipeline. The intake ports of the two main inert protection gas conveying pipelines are connected to gas storage tanks, and their outlet ports are respectively connected to the oxidant conveying pipeline and the main gasifying agent injection pipeline. On the main inert protection gas conveying pipeline, starting from the intake port side, a control valve, a first manual valve, and a first check valve are successively connected;

[0012] The injection well is opened on the ground. The oxidant conveying pipeline and the main gasifying agent injection pipeline respectively transport the oxidant and the gasifying agent into the underground gasifier through the injection well.

[0013] As a further optimized solution of the present utility model, the oxidant and the gasifying agent are respectively supplied by a gas production device and a water production device. The gas production device and the water production device are respectively connected to the intake ports of the oxidant conveying pipeline and the main gasifying agent injection pipeline. A carbon dioxide supply device is arranged on one side of the gas storage tank located on the gasifying agent injection mechanism. A differential pressure interlock is arranged between the first pressure transmitter, the second pressure transmitter, the emergency cut-off valve, and the control valve.

[0014] As a further optimized solution of the present utility model, the gas outlet ports of the oxidant delivery pipeline and the main gasifier injection pipeline are jointly connected to a coiled tubing channel. The gas outlet port of the coiled tubing channel extends from the injection well to the underground gasifier. A branch pipeline for delivering inert protective gas is connected to the position between the second pressure transmitter and the first flowmeter on the main gasifier injection pipeline. The branch pipeline for delivering inert protective gas extends from the injection well to the underground gasifier. The branch pipeline for delivering inert protective gas is sequentially connected with a second manual valve, a second gasifier flowmeter, and a check valve starting from one side of the air inlet port.

[0015] As a further optimized solution of the present utility model, one end of the main pipeline for delivering inert protective gas close to the gas storage tank is connected with a gas pipe joint. A pipe interface is provided on the surface of the gas storage tank for connecting with the gas pipe joint. A clamping component is arranged on the gas pipe joint. The clamping component includes a collar and a clamping plate. An installation groove is provided on the surface of the gas pipe joint. The collar is sleeved in the installation groove and slides along the inner wall of the installation groove. A sliding groove is provided on the surface of the installation groove close to the pipe interface. The clamping plate is slidably connected in the sliding groove. An arc-shaped groove is provided on the surface of the collar close to the sliding groove. A fixing block is connected to one side of the clamping plate close to the arc-shaped groove. The fixing block extends into the arc-shaped groove and slides along the arc-shaped groove. A clamping groove corresponding to the clamping plate is provided on the inner wall of the pipe interface. Rotating the collar can drive the clamping plate to be inserted into the clamping groove, thereby connecting the delivery gas pipe and the gas storage tank.

[0016] As a further optimized solution of the present utility model, the clamping component further includes a triggering member. The triggering member is connected to the surface of the collar. The triggering member extends to the outside of the installation groove. A fixing component is connected to the surface of the triggering member for fixing the clamping plate in the clamping groove.

[0017] As a further optimized solution of the present utility model, the fixing component includes ear plates connected to the surface of the triggering member and the surface of the gas pipe joint. The two ear plates are connected by bolts.

[0018] As a further optimized solution of the present utility model, a limiting component is arranged on the pipe interface for aligning the position of the clamping plate and the clamping groove when the gas pipe joint is inserted into the pipe interface.

[0019] As a further optimized solution of the present utility model, the limiting component includes a limiting block. The limiting block is connected to the inner wall of the pipe interface. A limiting groove cooperating with the limiting block is provided on the surface of the gas pipe joint. The diameter of one end of the pipe interface close to the gas storage tank is reduced, and an abutting portion is formed on its inner wall. The abutting portion limits the insertion depth of the gas pipe joint into the pipe interface.

[0020] The beneficial effects of the present utility model are as follows: The present utility model provides multiple channels for raw material injection, making the gasification reaction more complete, and can prevent the phenomenon that the check valve cannot be sealed or the sealing surface is damaged, resulting in the underground syngas flowing into the oxidant delivery pipeline or the gasifying agent injection pipeline. The inert protection gas mechanism ensures the safe operation of the process through differential pressure interlock. During shutdown and maintenance, this system can also be used for pipeline purging. Brief Description of the Drawings

[0021] Figure 1 is the overall structural schematic diagram of Embodiment 1 of the present utility model;

[0022] Figure 2 is the connection schematic diagram of the pipe interface and the gas pipe joint of Embodiment 2 of the present utility model;

[0023] Figure 3 is the structural schematic diagram of the collar of Embodiment 2 of the present utility model;

[0024] Figure 4 is the internal structural schematic diagram of the pipe interface and the gas pipe joint of Embodiment 2 of the present utility model;

[0025] Figure 5 is Figure 4 the enlarged view at A in

[0026] Figure 6 is the structural schematic diagram of the limit groove of Embodiment 2 of the present utility model;

[0027] Figure 7 is the position schematic diagram of two groups of ear plates of Embodiment 2 of the present utility model.

[0028] In the figure: 1. Oxidant; 2. Pressure transmitter I; 3. Emergency cut-off valve I; 4. Inert protection gas storage tank I; 5. Control valve I; 6. Check valve I; 7. Pressure transmitter III; 8. Oxidant flowmeter; 9. Check valve III; 10. Coiled tubing channel; 11. Injection well; 12. Underground gasifier; 13. Gasifying agent; 14. Pressure transmitter II; 15. Emergency cut-off valve II; 16. Carbon dioxide supply device; 17. Inert protection gas storage tank II; 18. Control valve II; 19. Check valve II; 20. Pressure transmitter IV; 21. Gasifying agent flowmeter I; 22. Check valve IV; 23. Gasifying agent flowmeter II; 24. Check valve; 25. Gas storage tank; 26. Pipe interface; 27. Gas pipe joint; 28. Collar; 29. Card plate; 30. Chute; 31. Arc groove; 32. Fixed block; 33. Limit block; 34. Limit groove; 35. Abutting portion; 36. Triggering member; 37. Ear plate; 38. Card slot. Detailed Embodiment

[0029] The present application will be further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0030] Embodiment 1

[0031] As Figure 1 shown, a raw material injection system for an underground coal gasification process includes an oxidant delivery mechanism, a gasifying agent injection mechanism, an injection well 11, and an underground gasification furnace 12; the oxidant delivery mechanism includes an oxidant delivery pipeline, and the gasifying agent injection mechanism includes a main gasifying agent injection pipeline. On the oxidant delivery pipeline and the main gasifying agent injection pipeline, starting from the intake port side, a first pressure transmitter, an emergency cut-off valve, an inert protection gas mechanism, a second pressure transmitter, a first flowmeter, and a second check valve are successively connected. A bypass valve group is provided on one side of the emergency cut-off valve. The purpose of setting the bypass valve group is: it can reduce the pressure impact during startup, or when the main pipeline needs to be repaired or replaced, the bypass valve group can keep the system running and prevent a complete shutdown;

[0032] The inert protection gas mechanisms each include a main inert protection gas delivery pipeline. The intake ports of the two main inert protection gas delivery pipelines are both connected to a gas storage tank 25, and their outlet ports are respectively connected to the oxidant delivery pipeline and the main gasifying agent injection pipeline. On the main inert protection gas delivery pipeline, starting from the intake port side, a control valve, a first manual valve, and a first check valve are successively connected;

[0033] The injection well 11 is opened on the ground. The oxidant delivery pipeline and the main gasifying agent injection pipeline respectively deliver an oxidant 1 and a gasifying agent 13 into the underground gasification furnace 12 through the injection well 11.

[0034] Specifically, the first pressure transmitter includes a pressure transmitter one 2 and a pressure transmitter two 14, the emergency cut-off valve includes an emergency cut-off valve one 3 and an emergency cut-off valve two 15, the gas storage tank 25 includes an inert protection gas storage tank one 4 and an inert protection gas storage tank two 17, the control valve includes a control valve one 5 and a control valve two 18, the first check valve includes a check valve one 6 and a check valve two 19, the second pressure transmitter includes a pressure transmitter three 7 and a pressure transmitter four 20, the first flowmeter includes an oxidant flowmeter 8 and a gasifying agent flowmeter one 21, and the second check valve includes a check valve three 9 and a check valve four 22;

[0035] The pressure transmitter one 2, the emergency cut-off valve one 3, the pressure transmitter three 7, the oxidant flowmeter 8, and the check valve three 9 are provided on the oxidant delivery pipeline;

[0036] The pressure transmitter II 14, the emergency cut-off valve II 15, the pressure transmitter IV 20, the gasifying agent flowmeter I 21, and the check valve IV 22 are arranged on the gasifying agent injection pipeline;

[0037] The inert protective gas storage tank I 4, the control valve I 5, and the check valve I 6 are arranged on the inert protective gas transmission pipeline connected to the oxidant transmission pipeline.

[0038] The inert protective gas storage tank II 17, the control valve II 18, and the check valve II 19 are arranged on the inert protective gas transmission pipeline connected to the main gasifying agent injection pipeline.

[0039] It should be noted that at least one low point drain valve is respectively arranged on the oxidant transmission pipeline and the gasifying agent transmission pipeline. Other safety accessories should be arranged on the oxidant transmission pipeline, the gasifying agent transmission pipeline, and the inert protective gas transmission pipeline, specifically including a thermometer, a safety valve, a pressure gauge, a filter, an oxygen pipeline flame arrester, etc.

[0040] In this embodiment, the material of the oxidant transmission pipeline should have good oxidation resistance and strength. Preferably, it is 304 or 316L stainless steel or above. Preferably, the welding method of tungsten inert gas welding for backing, manual arc welding for filling and surfacing is adopted. The diameter of the oxidant transmission pipeline is preferably 50 - 150 mm according to the process requirements;

[0041] The pressure transmitter I 2 and the pressure transmitter III 7 on the oxidant transmission pipeline are preferably made of stainless steel, and the explosion-proof grade meets Exd ⅡB T4 and above;

[0042] The oxidant flowmeter 8 is used to accurately control the input amount of the oxidant in the pipeline and optimize the production process. Specifically, a vortex flowmeter, a mass flowmeter, an orifice plate flowmeter, etc. can be selected;

[0043] Before installation, the oxidant transmission pipeline and the valves and instruments installed on the oxidant transmission pipeline (referring to flowmeters, emergency cut-off valves, check valves, etc.) must be clean, free of grease, dust, rust, and other impurities, and strict degreasing and cleaning treatments must be carried out;

[0044] The material of the gasifying agent transmission pipeline and the instruments and valves installed on the gasifying agent transmission pipeline is preferably 304 or 316 stainless steel or above, and the diameter of the gasifying agent transmission pipeline is preferably 25 - 100 mm;

[0045] The gasifying agent flowmeter I 21 and the gasifying agent flowmeter II 23 are made of corrosion-resistant materials, such as stainless steel, etc. Specifically, an electromagnetic flowmeter, a turbine flowmeter, an ultrasonic flowmeter, etc. can be selected;

[0046] The emergency cut-off valve can be a gate valve, a ball valve, a butterfly valve, etc., and the actuator can be a pneumatic or electric actuator;

[0047] At least one blowdown valve is provided on both the oxidant delivery pipeline and the gasifying agent injection main pipeline for maintenance, replacement, and purging;

[0048] The gas source of the inert protective gas includes any one or both of a gas cylinder and a gas production device;

[0049] The purity of the inert protective gas meets the process requirements of 99.99% or above;

[0050] The control valve can be a gate valve, ball valve, butterfly valve, globe valve, etc., and the actuator can be a pneumatic or electric actuator. The pipeline and valves should be cleaned and degreased in accordance with the oxygen pipeline specifications;

[0051] Except for maintenance, the manual valve on the inert protective gas pipeline should be kept open.

[0052] Further, the oxidant 1 and the gasifying agent 13 are respectively supplied by a gas production device and a water production device. The gas production device and the water production device are respectively connected to the intake ports of the oxidant delivery pipeline and the gasifying agent injection main pipeline. One side of the gas storage tank 25 located on the gasifying agent injection mechanism is connected with a carbon dioxide supply device 16. A differential pressure interlock is set between the first pressure transmitter, the second pressure transmitter, the emergency cut-off valve, and the control valve.

[0053] By setting a differential pressure interlock between the first pressure transmitter, the second pressure transmitter, the emergency cut-off valve, and the control valve, a safety interlock control system is formed. The inert protective gas mechanism cooperates with the safety interlock control system to ensure the safe operation of the process. During shutdown and maintenance, this system can also be used for pipeline purging. The utilization of carbon dioxide as a raw material gas in the underground coal gasification process further improves the effective components of the syngas and increases the economic benefits.

[0054] Specifically, the differential pressure interlock on the oxidant delivery channel is that the pressure difference between the pressure transmitter one 2 and the pressure transmitter three 7 controls the opening and closing of the emergency cut-off valve one 3. When the pressure difference between the pressure transmitter one 2 and the pressure transmitter three 7 is greater than or equal to 0.2 MPa, the emergency cut-off valve one 3 closes to cut off the oxidant delivery in the oxidant delivery pipeline. During normal operation, the oxidant continues to be transported to the underground gasification furnace 12 through the oxidant flowmeter 8 and the check valve three 9;

[0055] The differential pressure interlock on the gasifying agent injection channel is that the pressure difference between the pressure transmitter two 14 and the pressure transmitter four 20 controls the opening and closing of the emergency cut-off valve two 15. When the pressure difference between the pressure transmitter two 14 and the pressure transmitter four 20 is greater than or equal to 5 kPa, the emergency cut-off two closes to cut off the gasifying agent delivery in the gasifying agent injection main pipeline. During normal operation, the manual valve can be used to select whether the gasifying agent is directly transported to the underground gasification furnace 12 through the main road continuous oil pipe channel 10 or is transported to the underground gasification furnace 12 through the inert protective gas delivery branch pipeline.

[0056] Further, the outlet ports of the oxidant delivery pipeline and the main gasifier agent injection pipeline are jointly connected to a coiled tubing channel 10. The outlet port of the coiled tubing channel 10 extends from the injection well 11 into the underground gasifier 12. A branch pipeline for delivering inert protective gas is connected to the position on the main gasifier agent injection pipeline between the second pressure transmitter and the first flowmeter. The main pipeline for delivering inert protective gas and the branch pipeline for delivering inert protective gas form an inert protective gas delivery pipeline. The branch pipeline for delivering inert protective gas extends from the injection well 11 into the underground gasifier 12. The branch pipeline for delivering inert protective gas is sequentially connected with a second manual valve, a second gasifier agent flowmeter 23, and a check valve 24 starting from one side of the inlet port.

[0057] In the inert protective gas mechanism connected to the oxidant delivery pipeline, a differential pressure interlock is set between the control valve I 5, the pressure transmitter I 2, and the pressure transmitter III 7. When the differential pressure interlock system is triggered, the control valve I 5 on the inert protective gas delivery pipeline will be activated, thereby delivering inert gas to the oxidant delivery pipeline;

[0058] In the inert protective gas mechanism connected to the main gasifier agent injection pipeline, a differential pressure interlock is set between the control valve II 18, the pressure transmitter II 14, and the pressure transmitter IV 20. When the differential pressure interlock system is triggered, the control valve II 18 on the inert protective gas delivery pipeline will be activated to deliver inert gas to the gasifier agent injection pipeline. Additionally, this system can also be used to deliver carbon dioxide 16 into the underground gasifier 12 to participate in the reaction, improve the effective components of the syngas, and improve economic benefits.

[0059] Example 2

[0060] In this embodiment, an air pipe joint is added on the basis of Embodiment 1, which is used to connect the main pipeline for transporting inert protective gas and the gas storage tank 25, changing the conventional connection methods (such as flange connection, threaded connection, etc.), and providing convenience for the connection between the two. Specifically, one end of the main pipeline for transporting inert protective gas close to the gas storage tank is connected with an air pipe joint 27, a pipe interface 26 is provided on the surface of the gas storage tank 25 for connecting with the air pipe joint 27, a clamping component is arranged on the air pipe joint 27, and the clamping component includes a collar 28 and a clamping plate 29. An installation groove is provided on the surface of the air pipe joint 27, the collar 28 is sleeved in the installation groove and slides along the inner wall of the installation groove. A sliding groove 30 is provided on one side surface of the installation groove close to the pipe interface 26, the clamping plate 29 is slidably connected in the sliding groove 30. An arc groove 31 is provided on one side surface of the collar 28 close to the sliding groove 30, a fixing block 32 is connected to one side of the clamping plate 29 close to the arc groove 31, the fixing block 32 extends into the arc groove 31 and slides along the arc groove 31. A clamping groove 38 corresponding to the clamping plate 29 is provided on the inner wall of the pipe interface 26. Rotating the collar 28 can drive the clamping plate 29 to be inserted into the clamping groove 38, so as to connect the conveying air pipe and the gas storage tank 25.

[0061] Furthermore, the clamping component further includes a trigger 36, the trigger 36 is connected to the surface of the collar 28, the trigger 36 extends outside the installation groove, and a fixing component is connected to the surface of the trigger 36 for fixing the clamping plate 29 in the clamping groove 38.

[0062] It should be noted that the part of the trigger 36 located outside the installation groove fits the surface of the air pipe joint 27 and slides along its surface.

[0063] Furthermore, the fixing component includes ear plates 37 connected to the surface of the trigger 36 and the surface of the air pipe joint 27, and the two groups of ear plates 37 are connected by bolts.

[0064] Furthermore, a limiting component is arranged on the pipe interface 26 for aligning the position of the clamping plate 29 with the clamping groove 38 when the air pipe joint 27 is inserted into the pipe interface 26.

[0065] Furthermore, the limiting component includes a limiting block 33, the limiting block 33 is connected to the inner wall of the pipe interface 26, a limiting groove 34 matching the limiting block 33 is provided on the surface of the air pipe joint 27, the diameter of one end of the pipe interface 26 close to the gas storage tank 25 is reduced, and an abutting portion 35 is formed on its inner wall, and the abutting portion 35 limits the insertion depth of the air pipe joint 27 into the pipe interface 26.

[0066] In actual use, when inserting the air pipe joint 27 into the pipe interface 26, first align the limit groove 34 with the limit block 33, and then insert the air pipe joint 27 into the pipe interface 26. When the air pipe joint 27 contacts the abutting portion 35, it means that the clamping plate 29 is aligned with the clamping groove 38. At this time, the trigger member 36 can be rotated to drive the collar 28 to rotate, so that the clamping plate 29 is inserted into the clamping groove 38. When the clamping plate 29 is completely inserted into the clamping groove 38, the two ear plates 37 contact each other. At this time, bolts can be used to connect the two ear plates 37, thereby restricting the rotation of the trigger member 36.

[0067] It should be noted that a circular plate is sleeved on the outer surface of the air pipe joint 27. After the pipe interface 26 is connected to the air pipe joint 27, the circular plate abuts against the surface of the pipe interface 26, and a rubber pad can be provided on the surface in contact with the pipe interface 26 to enhance the sealing performance.

[0068] It should be further noted that for the pipeline connection structure provided in this embodiment, the time required to connect multiple groups of bolts when using a flange to connect the gas storage tank 25 and the inert protection gas delivery air pipe is saved, making the connection more convenient and improving the connection efficiency. At the same time, compared with using threads to connect the gas storage tank 25 and the inert protection gas delivery air pipe, the pipeline connection structure provided in this embodiment has better sealing performance.

[0069] The above-described embodiments only represent several implementation manners of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A raw material injection system for an underground coal gasification process, characterized in that, It includes an oxidant conveying mechanism, a gasifying agent injection mechanism, an injection well (11) and an underground gasifier (12); The oxidant delivery mechanism includes an oxidant delivery pipeline, and the gasifying agent injection mechanism includes a gasifying agent injection main pipeline. The oxidant delivery pipeline and the gasifying agent injection main pipeline are connected in sequence from the air inlet port side to a first pressure transmitter, an emergency shut-off valve, an inert protective gas mechanism, a second pressure transmitter, a first flow meter, and a second check valve. A bypass valve group is provided on one side of the emergency shut-off valve. The inert protective gas mechanism comprises an inert protective gas delivery main pipeline, the air inlet ports of the two groups of the inert protective gas delivery main pipelines are connected to a gas storage tank (25), and the air outlet ports thereof are respectively connected to the oxidant delivery pipeline and the gasifying agent injection main pipeline, and the inert protective gas delivery main pipeline is sequentially connected to a control valve, a first manual valve and a first check valve from one side of the air inlet port; The injection well (11) is opened on the ground, and the oxidant delivery pipeline and the gasifying agent injection main pipeline respectively transport the oxidant (1) and the gasifying agent (13) to the underground gasifier (12) through the injection well (11).

2. The raw material injection system for the underground coal gasification process according to claim 1, characterized in that: The oxidant (1) and the gasifying agent (13) are supplied by a gas-making device and a water-making device, respectively. The gas-making device and the water-making device are respectively connected to the air inlet ports of the oxidant delivery pipeline and the gasifying agent injection main pipeline. A carbon dioxide supply device (16) is connected to one side of the gas storage tank (25) located on the gasifying agent injection mechanism. A pressure differential interlock is set between the first pressure transmitter, the second pressure transmitter, the emergency shut-off valve, and the control valve.

3. A raw material injection system for an underground coal gasification process according to claim 2, characterized in that: The outlet ports of the oxidant delivery pipeline and the gasifying agent injection main pipeline are commonly connected to a continuous oil pipe channel (10), and the outlet port of the continuous oil pipe channel (10) extends from the injection well (11) to the underground gasifier (12). An inert protective gas delivery branch pipeline is connected to a position between the second pressure transmitter and the first flow meter on the gasifying agent injection main pipeline, and the inert protective gas delivery branch pipeline extends from the injection well (11) to the underground gasifier (12). The inert protective gas delivery branch pipeline is sequentially connected to a second manual valve, a second gasifying agent flow meter (23) and a check valve (24) from one side of the air inlet port.

4. A raw material injection system for an underground coal gasification process according to claim 3, characterized in that: One end of the main inert protective gas delivery pipeline close to the gas storage tank is connected with a tracheal joint (27). A pipe interface (26) is provided on the surface of the gas storage tank (25) for connecting with the tracheal joint (27). A clamping component is arranged on the tracheal joint (27). The clamping component includes a collar (28) and a clamping plate (29). An installation groove is formed on the surface of the tracheal joint (27). The collar (28) is sleeved in the installation groove and slides along the inner wall of the installation groove. A sliding groove (30) is formed on one side surface of the installation groove close to the pipe interface (26). The clamping plate (29) is slidably connected in the sliding groove (30). An arc-shaped groove (31) is formed on one side surface of the collar (28) close to the sliding groove (30). A fixing block (32) is connected to one side of the clamping plate (29) close to the arc-shaped groove (31). The fixing block (32) extends into the arc-shaped groove (31) and slides along the arc-shaped groove (31). A clamping groove (38) corresponding to the clamping plate (29) is formed on the inner wall of the pipe interface (26). Rotating the collar (28) can drive the clamping plate (29) to be inserted into the clamping groove (38), so as to connect the delivery air pipe and the gas storage tank (25).

5. A raw material injection system for an underground coal gasification process according to claim 4, characterized in that: The clamping component further includes a trigger (36). The trigger (36) is connected to the surface of the collar (28). The trigger (36) extends outside the installation groove. A fixing component is connected to the surface of the trigger (36) for fixing the clamping plate (29) in the clamping groove (38).

6. The raw material injection system for underground coal gasification process according to claim 5, characterized in that: The fixing component includes ear plates (37) connected to the surface of the trigger (36) and the surface of the tracheal joint (27). The two groups of ear plates (37) are connected by bolts.

7. A raw material injection system for an underground coal gasification process according to claim 4, characterized in that: A limiting component is arranged on the pipe interface (26) for aligning the position of the clamping plate (29) and the clamping groove (38) when the tracheal joint (27) is inserted into the pipe interface (26).

8. A raw material injection system for an underground coal gasification process according to claim 7, characterized in that: The limiting component includes a limiting block (33). The limiting block (33) is connected to the inner wall of the pipe interface (26). A limiting groove (34) matched with the limiting block (33) is formed on the surface of the tracheal joint (27). The diameter of one end of the pipe interface (26) close to the gas storage tank (25) is reduced, and an abutting part (35) is formed on its inner wall. The abutting part (35) limits the insertion depth of the tracheal joint (27) into the pipe interface (26).

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