UCG laser ignition system

Abstract

The utility model discloses a UCG laser ignition system, and relates to the technical field of underground coal gasification, in particular to the UCG laser ignition system. Comprising a laser pump, a blowout preventer, an optical cable and a laser spark plug integration device. The blowout preventer is fixedly installed at a wellhead of the vertical shaft, the bottom of the vertical shaft extends into an underground coal seam, the wellhead is sealed through the blowout preventer, and a high-pressure oxidizing agent is injected into the vertical shaft; the laser pump is fixedly mounted on the ground; the laser spark plug integrated device is lowered to the bottom of the vertical shaft through an optical cable; the laser spark plug integration device comprises a thermal infrared imager, a pressure sensor, an oxygen sensor and a laser spark plug. According to the utility model, the laser igniter is used for directly igniting in the coal seam through the laser beam, so that the in-situ gasification of coal is realized, the energy conversion efficiency of the laser ignition technology is high, and the efficient ignition effect can be achieved under the condition of lower energy consumption.

Description

TECHNICAL FIELD

[0001] The utility model relates to underground coal gasification technical field especially is UCG laser ignition system. BACKGROUND

[0002] The industry often takes underground coal gasification (also called underground coal mining, Underground Coal Gasification, UCG) as one of coal natural gas. UCG needs to be converted into gas under certain temperature and pressure, and the oxidant (air or oxygen and steam) is ignited to obtain crude water coal gas, and through subsequent desulfurization and decarburization process, refined carbon monoxide gas can be obtained. In this way, how to safely and stably ignite, avoid early flame extinguishing, partial combustion, non-ignition, becomes one of the key technologies of UCG. CONTENT OF THE UTILITY MODEL

[0003] The utility model provides a kind of UCG laser ignition system for the above problems, and it is safe, stable to ignite in the process of underground coal mining in combination with laser ignition.

[0004] The technical scheme of the utility model is as follows: including laser pump 1, blowout preventer 14, optical cable 2 and laser spark plug integrated device 3;

[0005] The blowout preventer 14 is fixedly installed at the wellhead of the shaft, the bottom of the shaft extends into the underground coal seam, the wellhead is sealed by the blowout preventer 14, and high-pressure oxidant is injected into the shaft;

[0006] The laser pump 1 is fixedly installed on the ground;

[0007] The laser spark plug integrated device 3 is lowered to the bottom of the shaft through the optical cable 2, and the optical cable 2 is formed by bundling optical fibers and cables together;

[0008] The laser spark plug integrated device 3 includes an infrared thermal imager 11, a pressure sensor 13, an oxygen sensor 12 and a laser spark plug 10, the laser spark plug 10 is connected with the laser pump 1 through an optical fiber, receives and focuses the laser generated by the laser pump 1 through the laser spark plug 10, and forms an ignition point;The infrared thermal imager 11, the pressure sensor 13 and the oxygen sensor 12 are connected with the cable respectively, the infrared thermal imager 11 is used to obtain images by using the infrared energy of coal seam combustion radiation, the pressure sensor 13 is used to detect the temperature of coal reaction, and the oxygen sensor 12 is used to analyze the oxygen concentration in the coal reaction process, and the signals collected by the three are transmitted back to the ground through the cable.

[0009] Further, the blowout preventer 14 is used for sealing the wellhead and injecting high-pressure oxidant into the sealed pipe;

[0010] The blowout preventer 14 adopts the blowout preventer of FHZ18-21 type, has a drift of 179.4 mm, a working pressure of 21 / 3000 MPa / psi, a strength test pressure of 42 / 6000 MPa / psi, a hydraulic control pressure less than or equal to 10.5 / 1500 MPa / psi, a closing oil volume of 800 liters, an opening oil volume of 926 liters, an external dimension of 1927 mm, and a whole machine weight of about 13.9 kg.

[0011] Further, the laser pump 1 adopts a semiconductor laser pumped solid laser, a high-power semiconductor laser side pump module SP17, and realizes a peak power output of 30kW.

[0012] The optical fiber adopts an air-core anti-resonant optical fiber to replace a solid-core quartz medium with air.

[0013] The laser spark plug 10 adopts a single platinum spark plug, contains a noble metal platinum in a center electrode, adopts a conical nickel-yttrium alloy side electrode, conical laser welds a conical yttrium gold side electrode, 360° laser welds a platinum center electrode, and is provided with a nickel-plated shell.

[0014] Further, the infrared thermal imager 11 adopts a ULTi32 high-temperature infrared thermal imager of Optasense.

[0015] Further, the pressure sensor 13 adopts a silicon-isolated high-temperature-resistant pressure sensor.

[0016] Further, the oxygen sensor 12 adopts an HMT oxygen probe.

[0017] Further, a sealing pipe 7 is arranged in the shaft, the sealing pipe 7 is lowered to a junction of a rock stratum and a coal seam, and the blowout preventer 14 is fixedly installed at a top opening of the sealing pipe 7.

[0018] The utility model takes into account that laser ignition technology is as an advanced ignition means, because of its high efficiency, safety, reliable and so on advantage, in recent years, receives extensive attention. Along with the rapid development of aviation, spaceflight, military and the like field, traditional ignition mode gradually shows its limitation, such as mechanical delay, electromagnetic interference and the like problem. Laser ignition technology utilizes high-energy laser pulse to directly ignite fuel or propellant, can effectively avoid the drawbacks of traditional ignition mode, improves the response speed and reliability of ignition system.

[0019] Compared with traditional ignition, laser ignition technology has a plurality of advantages, including being capable of accurately controlling ignition time and position, improving ignition energy, reducing ignition delay, reducing pollution gas emission, reducing heat loss during ignition and increasing lean combustion limit. These advantages make laser ignition technology have potential application value in UCG, avoid problems in ignition, such as early flame extinguishing, partial combustion, non-ignition and the like.

[0020] The utility model discloses a laser igniter directly ignites in the coal seam through laser beam, realizes the in situ gasification of coal, and the energy conversion efficiency of laser ignition technology is high, can reach the efficient ignition effect under the lower energy consumption, this helps to reduce the energy consumption of whole gasification process, and has the positive role to improve the utilization rate of coal resources and energy security. Through the in situ gasification coal in the ground, can reduce the damage of ground exploitation to the environment, and the laser ignition ignites the coal seam through forming high temperature and high pressure plasma, and the laser ignition energy is high, and the ignition energy conversion rate is high. And, the non - contact ignition has the advantages such as good cold start performance, adjustable ignition position, controllable ignition time and energy. With the continuous development of laser technology, the volume and cost of laser ignition system are gradually reduced, so that the technology is more practical and economical. BRIEF DESCRIPTION OF DRAWINGS

[0021] Fig. 1 It is the structure schematic diagram of UCG laser ignition system of the utility model;

[0022] Fig. 2 It is the construction schematic diagram of staggered position well drilling of the utility model;

[0023] Fig. 3 It is the schematic diagram of laser spark plug integrated device of the utility model;

[0024] Among them, 1, laser pump;2, optical cable line;3, laser spark plug integrated device;4, rock stratum;5, coal seam;6, wellhead no. 1;7, sealing pipe;8, wellhead no. 2;9, wellhead no. 3;10, laser spark plug;11, infrared thermal imager;12, oxygen sensor;13, pressure sensor;14, blowout preventer. DETAILED DESCRIPTION

[0025] To clearly illustrate the technical features of the patent, the patent is described in detail below through specific implementation manners and in conjunction with its drawings.

[0026] Referring to Figs. 1-3 , including:

[0027] Laser ignition system, the laser ignition system includes laser pump, optical fiber and laser spark plug;The laser pump is the energy source of laser ignition, is used to produce laser;The optical fiber transmits the laser produced by laser pump to the cylinder;The laser spark plug focuses laser and forms ignition point

[0028] Downhole sealing steam injection device, the downhole sealing steam injection device includes blowout preventer, cable, sealing pipe, and the blowout preventer is used to seal wellhead, and high-pressure oxidant is injected into the sealing pipe.

[0029] Reaction monitoring device, the reaction monitoring device includes infrared thermal imager, pressure sensor, oxygen sensor;The infrared thermal imager is used to obtain image by using the infrared energy of coal seam combustion radiation;Pressure sensor is used to detect the temperature of coal reaction;Oxygen sensor is used to analyze the oxygen concentration in the process of coal reaction.

[0030] As Fig. 2 As shown in the drawings, a plurality of shafts are punched from the ground to the middle position of the coal seam, and the first wellhead 6, the second wellhead 8 and the third wellhead 9 are distributed in staggered manner to realize multi-well production and reduce resource waste while taking into account production efficiency. The underground water and gas in the underground coal seam are discharged, and a downhole sealing steam injection device is installed, the downhole sealing steam injection device comprises a blowout preventer 14, a cable and a sealing pipe 7, the sealing pipe 7 is lowered to the junction of the rock layer and the coal seam, the blowout preventer 14 adopts a FHZ18-21 type blowout preventer with a drift diameter of 179.4 mm, a working pressure of 21 / 3000 MPa / psi, a strength test pressure of 42 / 6000 MPa / psi, a hydraulic control pressure less than or equal to 10.5 / 1500 MPa / psi, a closing oil volume of 800 liters, an opening oil volume of 926 liters, an outer dimension of 1927 mm and a total machine weight of about 13.9 kg. The blowout preventer is used to seal the wellhead and inject high-pressure oxidizing agent into the sealing pipe, and in actual operation, high-pressure air is injected into the sealing well through the blowout preventer by an additional pressurized air supply device, and then the well is sealed for subsequent ignition.

[0031] The laser spark plug integrated device 3 is lowered to the bottom of the well through the optical cable 2, and the infrared thermal imager 11, the pressure sensor 13, the oxygen sensor 12 and the laser spark plug 10 of the laser spark plug integrated device 3 are integrated, as Fig. 3The infrared thermal imager 11, the pressure sensor 13, and the oxygen sensor 12 are respectively connected with cables for returning electrical signals to the ground. The laser spark plug 10 adopts a single platinum spark plug with a noble metal platinum in the center electrode to provide strong power, and a conical nickel-yttrium alloy side electrode, a conical laser-welded conical yttrium side electrode to improve combustion performance and increase power, a 360° laser-welded platinum center electrode to ensure the durability of the noble metal spark plug, a nickel-plated shell for good engine protection, which can prevent cylinder head corrosion or cylinder pulling, a copper core, and a center electrode copper core design with good heat conduction capacity to prevent product overheating; at the same time, it has good resistance to electrical corrosion and chemical corrosion. The blue prismatic insulation design avoids the failure of ignition caused by flashover. The special ceramic material ensures better electrical performance for focusing laser of the laser spark plug to form an ignition point to ignite the coal bed. The laser pump 1 adopts a semiconductor laser pump solid-state laser (DPSSL) with high power, high beam quality output, small thermal effect, high efficiency, and compact device structure. The high-power semiconductor laser side pump module SP17 can realize a peak power output of 30kW, while realizing higher small signal gain multiple and better fluorescence distribution uniformity. The optical fiber and the cable are bundled together to form an optical cable 2. The upper interface of the optical fiber is connected with the ground laser pump, and the lower interface is connected with the downhole laser spark plug. The optical fiber has the advantages of low time delay, ultra-low nonlinearity, and potential ultra-low loss. The optical fiber adopts an air-core anti-resonant optical fiber to replace the solid core quartz medium with air. The SDH+air-core optical fiber is mixed with the glass core optical fiber. The laser pump 1, the optical fiber, and the laser spark plug 10 together form a laser ignition system.

[0032] The multi-well downhole laser spark plug integrated device 3 is stopped at the middle position of the coal bed, the blowout preventer 14 is used to seal the wellhead, high-pressure air is injected into the well to serve as an oxidizing agent for underground coal gasification, and a high-pressure environment is created underground to discharge water in the coal bed at the bottom. Then the laser pump 1 is started, the laser pump 1 generates laser, the laser is transmitted through the optical fiber, the laser spark plug 10 focuses the laser to form an ignition point, and the coal bed is ignited. During the combustion of the coal bed, the reaction monitoring device is used for monitoring at all times.

[0033] The reaction monitoring device includes the infrared thermal imager 10, the pressure sensor 13, and the oxygen sensor 12.

[0034] The infrared thermal imager 10 is used to acquire images by using infrared energy of coal bed combustion radiation. An Optex UTi32 high-temperature infrared thermal imager is adopted. The UTi32 is a thermal imager with a temperature measurement range of -20-1000℃, equipped with visible light and infrared lenses, LED lighting / photographing storage, and an emissivity adjustable range of 0.01-1.00.

[0035] The pressure sensor 13 adopts a silicon-isolated high-temperature-resistant pressure sensor, which can withstand instantaneous 2000 DEG C high-temperature impact, and is used for detecting the temperature of coal reaction.

[0036] The oxygen sensor 12 adopts an HMT oxygen probe, which is a high-temperature direct-insertion oxygen probe, is specially designed for use in a high-temperature environment, can detect the oxygen content of flue gas at a maximum working temperature of 1000 DEG C or above, is integrally formed by using a high-temperature low-eutectic-point welding technology, is coated with a precious metal alloy catalytic electrode and a composite material surface protection coating on the surface, improves the measurement accuracy, and enables the sensor to normally work in a high-dust and high-corrosion atmosphere environment, thereby greatly improving the service life and stability of the probe. With continuous combustion of the coal seam, the oxygen content in the underground decreases, and decreases to a certain value to stop the reaction, at which time the blowout preventer 14 is opened to recover the coal gas.

[0037] The utility model has many specific implementation ways, and the above is only the preferred implementation way of the utility model, and it should be pointed out that for ordinary skilled person in the art, on the premise of not departing from the principle of the utility model, a plurality of improvements can be made, and these improvements should be regarded as the protection scope of the utility model.

Claims

1. A UCG laser ignition system characterized by, It comprises a laser pump (1), a blowout preventer (14), an optical cable (2) and a laser spark plug integrated device (3); The blowout preventer (14) is fixedly installed at the wellhead of the shaft, the bottom of the shaft extends into the underground coal seam, the wellhead is sealed by the blowout preventer (14), and high-pressure oxidizing agent is injected into the shaft; The laser pump (1) is fixedly installed on the ground; The laser spark plug integrated device (3) is lowered to the bottom of the shaft through the optical cable (2), and the optical cable (2) is formed by bundling an optical fiber and a cable together; The laser spark plug integrated device (3) comprises an infrared thermal imager (11), a pressure sensor (13), an oxygen sensor (12) and a laser spark plug (10), the laser spark plug (10) is connected with the laser pump (1) through an optical fiber, receives and focuses the laser generated by the laser pump (1) through the laser spark plug (10) to form an ignition point, the infrared thermal imager (11), the pressure sensor (13) and the oxygen sensor (12) are connected with the cable respectively, the infrared thermal imager (11) is used to acquire images by using infrared energy radiated by coal seam combustion, the pressure sensor (13) is used to detect the temperature of coal reaction, and the oxygen sensor (12) is used to analyze the oxygen concentration in the coal reaction process, and the signals collected by the three are transmitted back to the ground through the cable.

2. A UCG laser ignition system as claimed in claim 1, wherein, The blowout preventer (14) is used for sealing the wellhead and injecting high-pressure oxidizing agent into the sealed pipe; The blowout preventer (14) adopts a blowout preventer of FHZ18-21 type, has a drift diameter of 179.4 mm, a working pressure of 21 / 3000 MPa / psi, a strength test pressure of 42 / 6000 MPa / psi, a hydraulic control pressure less than or equal to 10.5 / 1500 MPa / psi, a closing oil volume of 800 liters, an opening oil volume of 926 liters, an overall size of 1927 mm and a total weight of about 13.9 kg.

3. A UCG laser ignition system as claimed in claim 1, wherein, The laser pump (1) adopts a semiconductor laser pump solid-state laser, a high-power semiconductor laser side pump module SP17, and realizes a peak power output of 30kW; The optical fiber adopts an air-core anti-resonant optical fiber to replace the solid core quartz medium with air; The laser spark plug (10) adopts a single platinum spark plug, contains a noble metal platinum in the center electrode, adopts a conical nickel-yttrium alloy side electrode, conical laser welds the conical yttrium gold side electrode, 360° laser welds the platinum center electrode, and is plated with a nickel shell.

4. A UCG laser ignition system as claimed in claim 1, wherein, The infrared thermal imager (11) adopts a ULiDE UTi32 high-temperature infrared thermal imager.

5. A UCG laser ignition system as claimed in claim 1, wherein, The pressure sensor (13) adopts a silicon isolated high-temperature resistant pressure sensor.

6. A UCG laser ignition system as claimed in claim 1, wherein, The oxygen sensor (12) adopts an HMT oxygen probe.

7. A UCG laser ignition system as claimed in claim 1, wherein, A sealed pipe (7) is also arranged in the shaft, the sealed pipe (7) is lowered to the junction of the rock stratum and the coal seam, and the blowout preventer (14) is fixedly installed at the top of the sealed pipe (7).

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