Underground coal gasification ignition apparatus and method

Abstract

The present application relates to the technical field of underground coal gasification, and provides an underground coal gasification ignition apparatus and method, used for improving the success rate and reliability of ignition. The underground coal gasification ignition apparatus comprises a multi-channel coiled tubing, a burner, a first release sub, and a pyrotechnic ignition structure which are connected in sequence. The multi-channel coiled tubing and the burner are internally provided with a fuel injection channel and an oxygen injection channel, the burner is internally provided with a nozzle, and both the fuel injection channel and the oxygen injection channel are both in communication with the nozzle. When the pressure in the first release sub is greater than a set pressure, a first connecting member passing through and provided between the first release sub and the pyrotechnic ignition structure breaks, causing separation of the first release sub from the pyrotechnic ignition structure. An ignition device and a propellant grain are encapsulated in a housing of the pyrotechnic ignition structure. After the first connecting member breaks, the ignition device is activated and ignites the propellant grain to produce an ignition flame, the ignition flame initiates combustion of fuel exposed to the coal seam to produce a combustion flame, and the combustion flame ignites the coal seam.

Description

Coal underground gasification ignition device and method

[0001] The present application claims priority to the Chinese patent application No. 202411026450.8, filed on July 29, 2024, and entitled "Coal underground gasification ignition device and method", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of coal underground gasification, in particular to a coal underground gasification ignition device and method. BACKGROUND

[0003] Coal underground gasification is a process of realizing in-situ conversion of underground coal into combustible gas through combustion, which has the advantages of high efficiency, safety, environmental friendliness and high resource utilization rate. Underground ignition is to ignite the underground coal seam, which is the primary condition for starting coal underground gasification.

[0004] At present, the underground ignition methods include coke ignition, electric ignition and chemical ignition. The chemical ignition ignites the coal seam by injecting chemical agents and air into the coal seam and utilizing chemical heat release, which has simple process equipment and operation process.

[0005] However, the chemical ignition has low ignition success rate and poor combustion reliability after ignition. SUMMARY

[0006] The present application provides a coal underground gasification ignition device and method for providing ignition success rate and combustion reliability.

[0007] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0008] In one aspect, the present application provides a coal underground gasification ignition device, comprising a multi-channel continuous pipe, a burner, a first breakaway joint and a pyrotechnic ignition structure;

[0009] The multi-channel continuous pipe is connected to the burner, and the multi-channel continuous pipe and the burner have fuel injection channels and oxygen injection channels therein. The burner is provided with a nozzle, and the fuel injection channels and the oxygen injection channels are in communication with the nozzle;

[0010] The first end of the first breakaway joint is connected to the burner, and the second end of the first breakaway joint is provided with a first connecting piece between the shell of the pyrotechnic ignition structure. With the injection of oxygen and fuel, the pressure in the first breakaway joint gradually increases. When the pressure in the first breakaway joint is greater than the set pressure, the first connecting piece bears a load greater than the first preset load, the first connecting piece breaks, and the first breakaway joint is separated from the pyrotechnic ignition structure;

[0011] The shell of the pyrotechnic ignition structure encapsulates an ignition device and a propellant column, after the first connecting piece is broken, the ignition device is started and ignites the propellant column, forming an ignition flame, the ignition flame drives the fuel exposed in the coal seam to burn, forming a combustion flame, and the combustion flame ignites the coal seam.

[0012] Based on the above technical solutions, the application can also be improved as follows.

[0013] In a possible implementation, the ignition device includes an electric igniter, and the shell of the pyrotechnic ignition structure is provided with a control circuit and a top rod switch, and the control circuit is electrically connected with the electric igniter;

[0014] When the first connecting piece is not broken, the top rod switch abuts against the control circuit, and the control circuit is in an off state;

[0015] When the first connecting piece is broken, the top rod switch is separated from the control circuit, the control circuit is turned on, and after a preset time, the control circuit controls the electric igniter to ignite the propellant column.

[0016] In a possible implementation, the pyrotechnic ignition structure further includes an elastic safety device;

[0017] When the first connecting piece is not broken, one end of the elastic safety device abuts against the top rod switch, and the other end of the elastic safety device is arranged on the shell of the pyrotechnic ignition structure and abuts against the first breakaway joint;

[0018] When the first connecting piece is broken, the elastic safety device is ejected from the shell of the pyrotechnic ignition structure, so that the top rod switch is separated from the control circuit.

[0019] In a possible implementation, the multi-channel continuous pipe includes a continuous inner pipe, and the burner includes a transmission inner pipe, and the transmission inner pipe is communicated with the continuous inner pipe to form a fuel injection channel;

[0020] The multi-channel continuous pipe further includes a continuous outer pipe, and the continuous outer pipe and the continuous inner pipe have a first annular space; the burner further includes a transmission outer pipe, and the transmission outer pipe is communicated with the continuous outer pipe, and the transmission outer pipe and the transmission inner pipe have a second annular space, and the second annular space is communicated with the first annular space to form an oxygen injection channel.

[0021] In a possible implementation, the coal underground gasification ignition device further includes a tubular recess connector and a second breakaway joint;

[0022] The second breakaway joint includes a connecting outer shell and a connecting inner pipe, two ends of the connecting outer shell are connected with the recess connector and the transmission outer pipe respectively, and the connecting inner pipe is arranged in the connecting outer shell, and two ends of the connecting inner pipe are communicated with the continuous inner pipe and the transmission inner pipe respectively;

[0023] The first part of the dimple connector is mounted on the inner wall of the continuous outer pipe, the second part of the dimple connector is mounted on the inner wall of the connecting housing, and the second connecting member is arranged between the second part of the dimple connector and the connecting housing;

[0024] When the second connecting member bears a load greater than a second preset load, the second connecting member is broken to separate the dimple connector from the second release sub, and the second preset load is greater than the first preset load.

[0025] In a possible implementation, an annular centralizer is arranged in the dimple connector, the outer periphery of the centralizer is mounted on the connecting housing, and the inner periphery of the centralizer is sleeved on the connecting inner pipe.

[0026] The centralizer has an oxygen flow passage, and the two ends of the oxygen flow passage are respectively connected with the first annular space and the second annular space.

[0027] In a possible implementation, the first release sub and the shell of the pyrotechnic ignition structure are made of a combustible metal material.

[0028] In a possible implementation, the coal underground gasification ignition device further comprises a thermocouple, a cable and a monitoring system.

[0029] The thermocouple is arranged in the combustor and is used to obtain a combustion temperature, and the cable is connected with the thermocouple and the monitoring system to transmit temperature data to the monitoring system.

[0030] In a possible implementation, the coal underground gasification ignition device further comprises a combustible sleeve, and the multi-channel continuous pipe, the combustor, the first release sub and the pyrotechnic ignition structure are arranged in the combustible sleeve, and the combustible sleeve has a nitrogen injection passage.

[0031] In another aspect, the application provides a coal underground gasification ignition method, which uses the coal underground gasification ignition device in any of the above implementations, and the coal underground gasification ignition method comprises:

[0032] sequentially connecting the multi-channel continuous pipe, the combustor, the first release sub and the pyrotechnic ignition structure;

[0033] lowering the connected coal underground gasification ignition device to a to-be-ignited position in the well, injecting oxygen into the oxygen injection passage, injecting fuel into the fuel injection passage, and mixing and spraying the oxygen and the fuel at the nozzle of the combustor;

[0034] When the pressure in the first release sub is greater than a set pressure, the first connecting member arranged between the first release sub and the shell of the pyrotechnic ignition structure is broken, the first release sub and the pyrotechnic ignition structure are separated, and the oxygen and the fuel are exposed in the coal seam.

[0035] dragging the multi-channel coiled tubing in a direction towards the wellhead to drive the burner and the first release sub away from the pyrotechnic ignition structure;

[0036] The ignition device in the pyrotechnic ignition structure ignites the propellant in the pyrotechnic ignition structure to form an ignition flame, the ignition flame drives the fuel exposed in the coal seam to burn to form a combustion flame, and the combustion flame ignites the coal seam.

[0037] The coal underground gasification ignition device and method provided in the application have the following beneficial effects:

[0038] The coal underground gasification ignition device provided in the application comprises a multi-channel coiled tubing, a burner, a first release sub and a pyrotechnic ignition structure, which are connected through the multi-channel coiled tubing and the burner. The multi-channel coiled tubing and the burner have a fuel injection channel and an oxygen injection channel therein, and fuel and oxygen can be injected into the well. The burner is provided with a nozzle, and the oxygen injection channel and the fuel injection channel are both communicated with the nozzle, so that the fuel is atomized and mixed with the oxygen to be sprayed out, so that the fuel and the oxygen are fully contacted to improve the combustion stability. The two ends of the first release sub are connected with the burner and the pyrotechnic ignition structure respectively, so that the multi-channel coiled tubing, the burner, the first release sub and the pyrotechnic ignition structure are connected in sequence, thereby facilitating the lowering of the multi-channel coiled tubing, the burner, the first release sub and the pyrotechnic ignition structure into the well.

[0039] With more and more oxygen injected into the oxygen injection channel and more and more fuel injected into the fuel injection channel, the pressure in the first release sub becomes higher and higher. When the pressure in the first release sub is greater than a set pressure, the first connecting piece provided on the first release sub and the shell of the pyrotechnic ignition structure breaks, the first release sub is separated from the pyrotechnic ignition structure, and the mixture of oxygen and fuel sprayed out of the nozzle is exposed to the coal seam in the well. The ignition device provided in the pyrotechnic ignition structure ignites the propellant to form an ignition flame, the ignition flame drives the fuel exposed in the coal seam to burn to form a combustion flame, and the combustion flame ignites the coal seam. Compared with the related art, the coal underground gasification ignition device and method provided in the application separates the pyrotechnic ignition structure from the first release sub, the ignition device ignites the propellant to form an ignition flame and a combustion flame, thereby increasing the reliability and success rate of ignition. By continuously injecting fuel into the fuel injection channel, the combustion stability is ensured, by controlling the flow of oxygen injected into the oxygen injection channel, the combustion temperature is adjusted, and controllable combustion is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0041] Fig. 1 is a structural schematic diagram of a coal underground gasification ignition device provided by the present application;

[0042] Fig. 2 is a structural schematic diagram of a multi-channel continuous pipe, a pit connector and a second release sub provided by the present application;

[0043] Fig. 3 is a structural schematic diagram of a burner, a first release sub and a pyrotechnic ignition structure provided by the present application.

[0044] Legend: 100-multi-channel continuous pipe; 110-continuous inner pipe; 120-continuous outer pipe; 130-first annulus; 200-burner; 210-transport inner pipe; 220-transport outer pipe; 230-second annulus; 240-nozzle; 250-fuel check valve; 260-oxygen check valve; 270-flame arrestor; 300-first release sub; 310-first connecting piece; 320-valve; 400-pyrotechnic ignition structure; 410-ignition device; 420-charge column; 430-control circuit; 440-ejector rod switch; 450-elastic safety; 460-service safety; 500-pit connector; 510-centralizer; 600-second release sub; 610-connecting shell; 620-connecting inner pipe; 630-second connecting piece; 700-combustible casing; 710-nitrogen injection channel. DETAILED DESCRIPTION

[0045] Generally, the success rate of chemical ignition is low, and the combustion is unstable after ignition. The reason for this problem is that when the temperature in the well is low or there is water seepage in the well, the combustion time of the chemical agent is short, and the combustion is easy to extinguish after ignition, and the reliability of the combustion is poor.

[0046] In order to solve the above technical problems, in the coal underground gasification ignition device and method provided by the present application, after the pyrotechnic ignition structure is separated from the first release sub, the ignition device ignites the charge column to form an ignition flame and a combustion flame, thereby increasing the reliability and success rate of ignition. By continuously injecting fuel into the fuel injection channel, the combustion stability is ensured, and by controlling the oxygen flow injected into the oxygen injection channel, the combustion temperature is adjusted to achieve controllable combustion.

[0047] In order to make the above objectives, characteristics and advantages of the embodiments of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0048] As shown in FIG. 1, the coal underground gasification ignition device includes a multi-channel continuous pipe 100, a burner 200, a first release joint 300 and a firework ignition structure 400. The multi-channel continuous pipe 100 is connected to the burner 200, and the multi-channel continuous pipe 100 and the burner 200 have fuel injection channels and oxygen injection channels therein. The fuel injection channels are used for injecting fuel into the well, and the fuel can be one or more of gasoline, diesel and liquid hydrocarbon. The oxygen injection channels are used for injecting oxygen into the well, and the oxygen can be pure oxygen or mixed with other gases, for example, injecting oxygen-enriched air into the well.

[0049] For example, referring to FIG. 2, the multi-channel continuous pipe 100 includes a continuous inner pipe 110 and a continuous outer pipe 120, the continuous inner pipe 110 is located in the continuous outer pipe 120, and a first annular space 130 is formed between the continuous inner pipe 110 and the continuous outer pipe 120. Referring to FIG. 3, the burner 200 includes a transmission inner pipe 210 and a transmission outer pipe 220, and the transmission outer pipe 220 is connected to the continuous outer pipe 120, so that the burner 200 is connected to the multi-channel continuous pipe 100. A second annular space 230 is formed between the transmission inner pipe 210 and the transmission outer pipe 220.

[0050] The transmission inner pipe 210 is connected to the continuous inner pipe 110, thereby forming a fuel injection channel, and the fuel enters the well from the end of the continuous inner pipe 110 close to the wellhead via the continuous inner pipe 110 and the transmission inner pipe 210. The second annular space 230 is connected to the first annular space 130, thereby forming an oxygen injection channel, and the oxygen enters the well from the end of the first annular space 130 close to the wellhead via the first annular space 130 and the second annular space 230.

[0051] As shown in FIG. 3, a nozzle 240 is arranged in the burner 200, and the nozzle 240 is connected to the fuel injection channel and the oxygen injection channel of the nozzle 240, so that the oxygen and the fuel are mixed and atomized in the nozzle 240 and then sprayed out of the nozzle 240, so that the oxygen and the fuel can be fully contacted and fully combusted.

[0052] In some examples, referring to FIG. 3, the combustor 200 further comprises a fuel check valve 250 arranged along the fuel flow direction, an oxygen check valve 260 arranged along the oxygen flow direction, and a flame arrester 270 arranged behind the oxygen check valve 260. The fuel check valve 250 can prevent backflow of fuel. The oxygen check valve can prevent backflow of oxygen. The flame arrester 270 can prevent the passage of combustion flame, avoiding damage to the structure in front of the flame arrester 270, for example, avoiding damage to the fuel check valve 250.

[0053] As shown in FIGS. 1 and 3, the first breakaway joint 300 is a connecting structure between the combustor 200 and the pyrotechnic ignition structure 400. As shown in FIG. 3, the first end of the first breakaway joint 300 is connected to the combustor 200, for example, the first breakaway joint 300 and the combustor 200 are clamped or threadedly connected. The second end of the first breakaway joint 300 is provided with a first connecting piece 310 between the shell of the pyrotechnic ignition structure 400, for example, referring to FIG. 3, the outer wall of the pyrotechnic ignition structure 400 abuts against the inner wall of the second end of the first breakaway joint 300. In the circumferential direction of the pyrotechnic ignition structure 400, the first connecting piece 310 is provided between the first breakaway joint 300 and the shell of the pyrotechnic ignition structure 400, referring to FIG. 3, the number of first connecting pieces 310 can be two, and the two first connecting pieces 310 are coaxially arranged.

[0054] When the pressure in the first breakaway joint 300 is greater than the set pressure, the first connecting piece 310 bears a load greater than the first preset load, and the first connecting piece 310 breaks. The first connecting piece 310 can be a first shear pin, the first preset load can be the maximum bearing load of the first shear pin itself, and the set pressure can be the pressure in the first breakaway joint 300 when the first shear pin bears its maximum bearing load. As more and more oxygen and fuel are injected into the combustor 200, the pressure in the first breakaway joint 300 increases, and when the pressure in the first breakaway joint 300 is greater than the maximum bearing load of the first shear pin, the first shear pin breaks, and the first breakaway joint 300 and the pyrotechnic ignition structure 400 are separated. So that the oxygen and fuel can be exposed to the coal seam in the well.

[0055] In some examples, referring to FIG. 3, a valve 320 is provided on the first breakaway joint 300, and when the valve 320 is opened, the inside and outside of the first breakaway joint 300 are communicated. When the valve 320 is closed, the inside and outside of the first breakaway joint 300 are closed. By providing the valve 320 on the first breakaway joint 300, gas impurities inside the underground coal gasification ignition device can be discharged by the valve 320 before the injection of oxygen and fuel.

[0056] The shell of the pyrotechnic ignition structure 400 encapsulates the ignition device 410 and the propellant column 420. The ignition device 410 can include an electric igniter or a plasma igniter, etc. The propellant column 420 can encapsulate a combustible agent and an oxidizer, the combustible agent can be one or more of silane, phosphine, triethylborane, triethylaluminum, etc., and the oxidizer can be one or more of ammonium perchlorate, ammonium dinitramide, nitroform hydrazine, etc. The combustible agent and the oxidizer can be mixed and combusted under the action of the ignition device 410. Since the propellant column 420 encapsulating the combustible agent and the oxidizer is located in the pyrotechnic ignition structure 400, the ignition energy consumption is low, the external environment has little effect, and the ignition reliability is high.

[0057] When the first connecting piece 310 breaks, the ignition device 410 ignites the propellant column 420 to form an ignition flame, the ignition flame drives the fuel exposed in the coal seam to burn and form a combustion flame from the nozzle 240, and the combustion flame ignites the coal seam. Since the first connecting piece 310 breaks, the multi-channel continuous pipe 100, the burner 200 and the first release sub 300 can be gradually dragged in the direction towards the wellhead as the combustion flame gradually moves towards the wellhead, so that oxygen and fuel can be fully provided during the combustion process, avoiding interruption of the combustion, and improving the stability of the combustion.

[0058] In addition, the coal underground gasification ignition device provided by the embodiment of the present application can increase the reliability and success rate of ignition by separating the pyrotechnic ignition structure 400 from the first release sub 300, igniting the propellant column 420 by the ignition device 410 to form an ignition flame. By continuously injecting fuel into the fuel injection channel, the combustion stability is ensured, and by controlling the oxygen flow injected into the oxygen injection channel, the combustion temperature is adjusted to achieve controllable combustion.

[0059] In some embodiments, referring to FIG. 3, the ignition device 410 includes an electric igniter, and the shell of the pyrotechnic ignition structure 400 is provided with a control circuit 430 and a top rod switch 440. The control circuit 430 can be arranged on a circuit board, the circuit board is mounted on the electric igniter, the control circuit 430 and the electric igniter are electrically connected, and the control circuit 430 can control the electric igniter to start.

[0060] When the first connecting member 310 is not broken, the top rod switch 440 abuts against the control circuit 430, the control circuit 430 is in an off state, the electric igniter is not started, and the propellant 420 is not ignited. When the first connecting member 310 is broken, the top rod switch 440 is separated from the control circuit 430, the control circuit 430 is turned on, and after a preset time, the control circuit 430 controls the electric igniter to ignite the propellant 420. The preset time can be a delay time set in the control circuit 430. Within the preset time, the multi-channel coiled tubing 100, the burner 200 and the first release sub 300 can be pulled in a direction towards the wellhead, thereby protecting the multi-channel coiled tubing 100, the burner 200 and the first release sub 300.

[0061] The preset time can be 0.5-3 minutes, for example, 0.5 minutes, 1 minute, 2 minutes or 3 minutes. The specific value of the preset time is determined according to the working condition in the well, as long as the multi-channel coiled tubing 100, the burner 200 and the first release sub 300 can be moved away from the combustion position within the preset time.

[0062] In some embodiments, as shown in FIG. 3, the pyrotechnic ignition structure 400 further comprises an elastic safety device 450, which has a spring part. When the first connecting member 310 is not broken, one end of the elastic safety device 450 abuts against the top rod switch 440, thereby abutting the top rod switch 440 against the control circuit 430 and limiting the movement of the top rod switch 440. The other end of the elastic safety device 450 is arranged on the shell of the pyrotechnic ignition structure 400 and abuts against the inner wall of the first release sub 300. Thus, the elastic safety device 450 is fixed.

[0063] When the first connecting member 310 is broken, the first release sub 300 and the pyrotechnic ignition structure 400 are separated, the spring part of the elastic safety device 450 springs up, and the elastic safety device 450 is ejected from the shell of the pyrotechnic ignition structure 400, so that the elastic safety device 450 no longer limits the movement of the top rod switch 440. The top rod switch 440 is separated from the control circuit 430, so that the control circuit 430 is turned on and the control circuit 430 can control the electric igniter to ignite the propellant 420.

[0064] On the basis of the above-mentioned embodiments, as shown in FIG. 3, the pyrotechnic ignition structure 400 can further comprise a service safety device 460, one end of which abuts against the top rod switch 440 to limit the movement of the top rod switch 440, and the second end of which is fixed on the right shell of the pyrotechnic ignition structure 400. The service safety device 460 is a secondary safety device for preventing the safety function of the elastic safety device 450 in the pyrotechnic ignition structure 400 from failing. Before the coal underground gasification ignition device is lowered into the well, the service safety device 460 needs to be pulled out, so that when in the well, the movement of the top rod switch 440 is limited only by the elastic safety device 450.

[0065] In some embodiments, as shown in FIG. 1 and FIG. 2, the coal underground gasification ignition device further comprises a tubular pit connector 500 and a second breakaway joint 600. The multi-channel continuous pipe 100, the pit connector 500, the second breakaway joint 600 and the burner 200 are connected in sequence.

[0066] As shown in FIG. 2, the second breakaway joint 600 comprises a connecting outer shell 610 and a connecting inner pipe 620, the connecting inner pipe 620 is arranged in the connecting outer shell 610, and the two ends of the connecting inner pipe 620 are communicated with the continuous inner pipe 110 and the transmission inner pipe 210 respectively, thereby forming a fuel injection channel. The two ends of the connecting outer shell 610 are connected with the pit connector 500 and the transmission outer pipe 220 respectively, so that the pit connector 500, the second breakaway joint 600 and the burner 200 are connected in sequence, and the first annulus 130, the annulus between the connecting outer shell 610 and the connecting inner pipe 620 and the second annulus 230 form an oxygen injection channel.

[0067] As shown in FIG. 2, the left part of the pit connector 500 is mounted on the inner wall of the continuous outer pipe 120, for example, referring to FIG. 2, the left part of the pit connector 500 has a pit, under the action of mechanical pressure or thermal pressure, the side wall of the continuous outer pipe 120 is deformed to form a protrusion, and the protrusion is pressed into the pit, thereby connecting the pit connector 500 and the continuous outer pipe 120. The first part of the pit connector 500 and the continuous outer pipe 120 are sealed by a sealing gasket, a compression ring and a threaded ring.

[0068] Referring to FIG. 2, the right part of the pit connector 500 is mounted on the inner wall of the connecting outer shell 610, and the second connecting piece 630 is arranged between the right part of the pit connector 500 and the connecting outer shell 610. The second part of the pit connector 500 is mounted between the connecting outer shell 610 and sealed by a sealing gasket and a compression ring. Referring to FIG. 2, the number of the second connecting piece 630 can be two, and the two second connecting pieces 630 are coaxially arranged.

[0069] When the second connecting piece 630 bears a load greater than the second preset load, the second connecting piece 630 breaks. The second connecting piece 630 can be a second shear pin, and the second preset load can be the maximum bearing load of the second shear pin, when the load borne by the second shear pin exceeds the maximum bearing load of the second shear pin, the second shear pin breaks. For example, when the coal underground gasification ignition device is stuck in the well, the dragging force of the multi-channel continuous pipe 100 can be increased, so that the second shear pin breaks, and the multi-channel continuous pipe 100 is recovered and protected.

[0070] The second preset load at which the second connecting piece 630 breaks is greater than the first preset load at which the first connecting piece 310 breaks, so as to avoid the second connecting piece 630 from breaking during ignition.

[0071] In some embodiments, the recess connector 500 is provided with an annular centralizer 510, the inner periphery of the centralizer 510 is sleeved on the connecting inner tube 620, and the outer periphery of the centralizer 510 is mounted on the connecting outer shell 610, so that the connecting inner tube 620 is aligned with the continuous inner tube 110, and fuel leakage is avoided.

[0072] The centralizer 510 has an oxygen flow passage therein, and the two ends of the oxygen flow passage are communicated with the first annular space 130 and the second annular space 230, respectively. Thus, oxygen can flow through the centralizer 510 into the second annular space 230, facilitating oxygen injection.

[0073] In some embodiments, the first release sub 300 and the housing of the pyrotechnic ignition structure 400 are made of a combustible metal material, which can be an aluminum alloy, a magnesium alloy, or a titanium alloy, etc. When the combustion temperature in the well reaches the combustion temperature of the combustible metal material, the first release sub 300 and the pyrotechnic ignition structure 400 can be ignited and completely burned, reducing the residue in the well.

[0074] In some embodiments, the coal underground gasification ignition device further comprises a thermocouple, a cable and a monitoring system. The thermocouple is a temperature measuring device that converts temperature signals into electrical signals. The thermocouple is arranged in the burner 200, for example, the thermocouple can be arranged in the burner 200 near one side of the nozzle 240, so as to obtain the combustion temperature after the coal seam is burned. One end of the cable is electrically connected with the thermocouple, and the other end is electrically connected with the monitoring system, so as to transmit the combustion temperature data obtained by the thermocouple to the monitoring system. The monitoring system can be arranged on the ground outside the well, and by checking the combustion temperature data displayed on the monitoring system, the amount of oxygen injected into the well is adjusted, so as to control the combustion temperature, so that the combustion is controllable, and the stability of the combustion is further increased.

[0075] In some embodiments, as shown in FIG. 1, the coal underground gasification ignition device further comprises a combustible casing 700, and the multi-channel continuous tube 100, the burner 200, the first release sub 300 and the pyrotechnic ignition structure 400 are all arranged in the combustible casing 700.

[0076] The combustible casing 700 is the outermost pipeline of the coal underground gasification ignition device, which can protect the multi-channel continuous tube 100, the burner 200, the first release sub 300 and the pyrotechnic ignition structure 400 in the combustible casing 700. The combustible casing 700 has a nitrogen injection passage 710 therein, which can be an annular space formed between the combustible casing 700 and the multi-channel continuous tube 100, the burner 200, the first release sub 300 and the pyrotechnic ignition structure 400.

[0077] After the combustion in the well, the first release joint 300 and the pyrotechnic ignition structure 400 are disconnected, the oxygen and the fuel are exposed in the coal seam, and nitrogen can be injected into the well through the nitrogen injection channel to adjust the oxygen content in the well, adjust the combustion temperature, and increase the stability of the combustion. The material of the combustible casing pipe 700 can be aluminum alloy, magnesium alloy, or titanium alloy, etc. When the combustion temperature reaches the ignition point of the combustible casing pipe, the combustible casing pipe 700 burns, further igniting the coal seam.

[0078] The application also provides a coal underground gasification ignition method. The coal underground gasification ignition method uses the coal underground gasification ignition device in any of the above embodiments. The coal underground gasification ignition method comprises the following steps:

[0079] Step A: sequentially connect the multi-channel continuous pipe 100, the burner 200, the first release joint 300, and the pyrotechnic ignition structure 400. The connection relationship of the multi-channel continuous pipe 100, the burner 200, the first release joint 300, and the pyrotechnic ignition structure 400 can refer to the coal underground gasification ignition device in any of the above embodiments.

[0080] In addition, the pit connector 500 and the second release joint 600 can also be connected between the multi-channel continuous pipe 100 and the burner 200. Thus, when the coal underground gasification ignition device is stuck in the well, the second connector 630 provided between the pit connector 500 and the second release joint 600 is broken, the pit connector 500 and the second release joint 600 are separated, and the multi-channel continuous pipe 100 is conveniently recovered.

[0081] Step B: lower the connected coal underground gasification ignition device to the ignition position in the well. For example, the coal underground gasification ignition device is lowered to the ignition position by a continuous pipe operation machine. Oxygen is injected into the oxygen injection channel, fuel is injected into the fuel injection channel, and the oxygen and the fuel are mixed and sprayed at the nozzle 240 of the burner 200. The pressure in the first release joint 300 gradually increases. It should be noted that before the oxygen and the fuel are injected, the valve 320 provided on the first release joint 300 can be opened first. For example, before being lowered into the well, the valve 320 is opened on the ground, oxygen is injected into the oxygen injection channel, and then fuel is injected into the fuel injection channel. Before the fuel is injected, a certain amount of protective nitrogen is injected into the fuel injection channel, the injection flow rate is controlled so that the oxygen reaches the valve 320 before the fuel, and when the fuel flows at the valve 320, the valve 320 is closed and the injection of oxygen and fuel is stopped, thereby discharging the gas impurities in the coal underground gasification ignition device. Then, the connected coal underground gasification ignition device is lowered to the ignition position in the well. Then, the injection of oxygen and fuel is continued, so that the oxygen and the fuel are mixed and sprayed at the nozzle 240 of the burner 200.

[0082] Step C: When the pressure in the first breakaway joint 300 is greater than the set pressure, the first connecting member 310 provided between the first breakaway joint 300 and the housing of the pyrotechnic ignition structure 400 is broken, the first breakaway joint 300 and the pyrotechnic ignition structure 400 are separated, so that the oxygen and the fuel are exposed in the coal seam. The set pressure is the pressure in the first breakaway joint 300 when the first connecting member 310 is broken.

[0083] Step D: After the first connecting member 310 is broken, the multi-channel coiled tubing 100 is pulled in the direction of the wellhead, driving the burner 200 and the first breakaway joint 300 away from the pyrotechnic ignition structure 400, so that the multi-channel coiled tubing 100, the burner 200 and the first breakaway joint 300 are away from the ignition position, and the multi-channel coiled tubing 100, the burner 200 and the first breakaway joint 300 are protected.

[0084] Step E: The ignition device 410 in the pyrotechnic ignition structure 400 ignites the propellant 420 in the pyrotechnic ignition structure 400 to form an ignition flame, the ignition flame drives the fuel exposed in the coal seam to burn to form a combustion flame, and the combustion flame ignites the coal seam.

[0085] The coal underground gasification ignition device provided by the application embodiment can increase the reliability and success rate of ignition by separating the pyrotechnic ignition structure 400 from the first breakaway joint 300, igniting the propellant 420 by the ignition device 410 to form an ignition flame. By continuously injecting fuel into the fuel injection channel, the combustion stability is ensured, and by controlling the oxygen flow injected into the oxygen injection channel, the combustion temperature is adjusted to achieve controllable combustion.

[0086] The coal underground gasification ignition method provided by the application embodiment can increase the reliability and success rate of ignition by separating the pyrotechnic ignition structure 400 from the first breakaway joint 300, igniting the propellant 420 by the ignition device 410 to form an ignition flame. By continuously injecting fuel into the fuel injection channel, the combustion stability is ensured, and by controlling the oxygen flow injected into the oxygen injection channel, the combustion temperature is adjusted to achieve controllable combustion.

[0087] The embodiments or implementations in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the embodiments can be referred to each other.

[0088] It should be noted that the terms "in some embodiments", "in certain embodiments", "in one embodiment", "in another embodiment", "in some implementations", "in some examples" and the like, used in the description, are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics can be implemented in both the described embodiments and in other embodiments. That is, the particular features, structures, or characteristics are not limited to the described embodiments. It should also be noted that the terms "first", "second", and the like can be used herein to describe various elements in an example, but do not necessarily have to be used to describe only these various elements or steps in this example. Rather, such terms can be used herein to describe various elements or steps in one example, and these terms are used to describe different ones of the elements or steps in other examples.

[0089] In general, terminology can be understood at least in part from usage in context. For example, terms, "and", "or", or "and / or" as used herein can be understood as having the same meaning as "and / or" according to some applications of 37 C.F.R. § 1.412. Also, the singular forms "a", "an", and "the" used herein can imply "comprising", "including", and the like, but not necessarily limited to, singular entities: nevertheless, "a", "an", and "the" are used to refer to both singular and plural entities not only in the context of a particular embodiment, but also in the context of one or more particular embodiments.

[0090] It will be readily understood that the terms "on", "above", and "over", in the present disclosure, are to be interpreted in the broadest context to mean not only "directly on something" but also to include the meaning of "on something" with intervening features or layers therebetween, and not only to include the meaning of "above something" or "over something" but also to include the meaning of "above something" or "over something" without intervening features or layers therebetween (i.e., directly on something).

[0091] In addition, spatially relative terms, such as "beneath", "below", "lower", "above", "upper", and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. The devices can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0092] Finally, it should be noted that the above-described embodiments are merely intended for describing the technical solutions of the present application, but not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified or equivalent replacements can be made to some or all of the technical features; and such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A coal underground gasification ignition device, characterized by, The device comprises a multi-channel continuous tube, a burner, a first release joint and a pyrotechnic ignition structure. The multi-channel continuous tube is connected to the burner, and the multi-channel continuous tube has fuel injection channels and oxygen injection channels in the burner, and the burner is provided with a nozzle, and the fuel injection channels and the oxygen injection channels are communicated with the nozzle. The first end of the first release joint is connected to the burner, and the first connecting piece is arranged between the second end of the first release joint and the shell of the pyrotechnic ignition structure. With the injection of oxygen and fuel, the pressure in the first release joint gradually increases. When the pressure in the first release joint is greater than the set pressure, the first connecting piece bears a load greater than the first preset load, the first connecting piece breaks, and the first release joint is separated from the pyrotechnic ignition structure. The shell of the pyrotechnic ignition structure encapsulates an ignition device and a propellant column. After the first connecting piece breaks, the ignition device starts and ignites the propellant column to form an ignition flame, which drives the fuel exposed in the coal seam to burn and form a combustion flame, which ignites the coal seam.

2. The coal gasification ignition device according to claim 1, wherein The ignition device comprises an electric igniter, and the shell of the pyrotechnic ignition structure is provided with a control circuit and a top rod switch, and the control circuit is electrically connected to the electric igniter. When the first connecting piece is not broken, the top rod switch abuts against the control circuit, and the control circuit is in an off state. When the first connecting piece is broken, the top rod switch is separated from the control circuit, the control circuit is turned on, and after a preset time, the control circuit controls the electric igniter to ignite the propellant column.

3. The coal gasification ignition device of claim 2, wherein, The pyrotechnic ignition structure further comprises an elastic safety device. When the first connecting piece is not broken, one end of the elastic safety device abuts against the top rod switch, and the other end of the elastic safety device is arranged on the shell of the pyrotechnic ignition structure and abuts against the first release joint. When the first connecting piece is broken, the elastic safety device is ejected from the shell of the pyrotechnic ignition structure to separate the top rod switch from the control circuit.

4. The coal gasification ignition device according to any one of claims 1 to 3, wherein The multi-channel continuous tube comprises a continuous inner tube, the burner comprises a transmission inner tube, and the transmission inner tube is communicated with the continuous inner tube to form the fuel injection channel. The multi-channel continuous tube further comprises a continuous outer tube, and the continuous outer tube and the continuous inner tube have a first annular space. The burner further comprises a transmission outer tube, the transmission outer tube is communicated with the continuous outer tube, the transmission outer tube and the transmission inner tube have a second annular space, and the second annular space is communicated with the first annular space to form the oxygen injection channel.

5. The coal gasification ignition device of claim 4, wherein, The device further comprises a tubular pit connector and a second release joint. The second release joint comprises a connecting shell and a connecting inner tube. The two ends of the connecting shell are connected to the pit connector and the transmission outer tube respectively. The connecting inner tube is arranged in the connecting shell, and the two ends of the connecting inner tube are communicated with the continuous inner tube and the transmission inner tube respectively. The first part of the recess connector is mounted on the inner wall of the continuous outer tube, the second part of the recess connector is mounted on the inner wall of the connecting shell, and a second connecting piece is arranged between the second part of the recess connector and the connecting shell; When the second connecting piece bears a load greater than a second preset load, the second connecting piece breaks, so that the recess connector is separated from the second release sub, and the second preset load is greater than the first preset load.

6. The coal gasification ignition device of claim 5, wherein, An annular centralizer is arranged in the recess connector, the outer periphery of the centralizer is mounted on the connecting shell, and the inner periphery of the centralizer is sleeved on the connecting inner tube. The centralizer has an oxygen flow passage, and the two ends of the oxygen flow passage are respectively communicated with the first annular space and the second annular space.

7. The coal gasification ignition device according to any one of claims 1 to 3, wherein The first release sub and the shell of the pyrotechnic ignition structure are made of combustible metal materials.

8. The coal gasification ignition device according to any one of claims 1 to 3, wherein The coal underground gasification ignition device further comprises a thermocouple, a cable and a monitoring system; The thermocouple is arranged in the combustor, and is used to obtain a combustion temperature; the cable connects the thermocouple and the monitoring system, so as to transmit the temperature data to the monitoring system.

9. The coal gasification ignition device according to any one of claims 1 to 3, wherein The coal underground gasification ignition device further comprises a combustible sleeve, the multi-channel continuous tube, the combustor, the first release sub and the pyrotechnic ignition structure are arranged in the combustible sleeve, and the combustible sleeve has a nitrogen injection passage.

10. A method of igniting coal-mine gasification, characterized by, The coal underground gasification ignition device is used in the coal underground gasification ignition method, and the method comprises the following steps: The multi-channel continuous tube, the combustor, the first release sub and the pyrotechnic ignition structure are sequentially connected; The connected coal underground gasification ignition device is lowered to a to-be-ignited position in the well, oxygen is injected into the oxygen injection passage, fuel is injected into the fuel injection passage, the oxygen and the fuel are mixed and sprayed at the nozzle of the combustor; When the pressure in the first release sub is greater than a set pressure, the first connecting piece arranged between the first release sub and the shell of the pyrotechnic ignition structure breaks, and the first release sub is separated from the pyrotechnic ignition structure; The multi-channel continuous tube is pulled in the direction of the wellhead, so as to drive the combustor and the first release sub away from the pyrotechnic ignition structure; The ignition device in the pyrotechnic ignition structure ignites the propellant column in the pyrotechnic ignition structure to form an ignition flame, the ignition flame drives the fuel exposed in the coal seam to burn to form a combustion flame, and the combustion flame ignites the coal seam.

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