KR101272275B1 - Method and Apparatus for Underground Coal Gasification using Microwaves - Google Patents

Abstract

The present invention relates to a method and apparatus for producing a gas effective for power generation and fuel conversion, such as syngas or methane gas, from underground coal beds using microwaves. More specifically, the present invention relates to a method and apparatus for gasification of underground coal seams, which is easy to control transmission to underground storage layers and has little transmission loss by using microwaves having selective heating characteristics for coal pyrolysis.

Description

Method and Apparatus for Gasification of Underground Coal Layer Using Microwaves {Method and Apparatus for Underground Coal Gasification using Microwaves}

The present invention relates to a method and apparatus for producing a gas effective for power generation and fuel conversion, such as syngas or methane gas, from underground coal beds using microwaves. More specifically, the present invention relates to a method and apparatus for gasification of underground coal seams, which is easy to control transmission to underground storage layers and has little transmission loss by using microwaves having selective heating characteristics for coal pyrolysis.

In recent years, many countries around the world are making great efforts to develop clean alternative energy in preparation for global warming and depletion of petroleum resources. In particular, clean energy technology using coal, which has less regional bias and relatively rich reserves worldwide than oil, namely Integrated Gasification Combined Cycle (IGCC) or Coal to Liquids (CTL) And methanation technology are becoming realistic alternatives for the upcoming Oil Peak (Hubbert's Peak). However, air pollution, such as dust, greenhouse gases and acid gases, etc. generated during the fuel use process, including enormous socioeconomic costs such as safety accidents in the mining process of the coal, environmental damage, and recovery costs, etc. Costs act as a big burden.

Therefore, in recent years, the conventional coal mining process directly bores the borehole to the coal bed and injects air or oxygen with steam to gasify coal by incomplete combustion, and through the other gas pipe, syngas as a main product Underground Coal Gasification (UCG), which extracts (CO + H ₂ ) to the ground, is being reviewed. At this time, the gas extracted to the ground is converted into liquid fuel or chemical raw materials by IGCC power generation or FT (Fischer-Tropsch) synthesis through purification process and used as an effective energy source.

This underground coal gasification method was first proposed by Sir William Siemens of Germany in 1868, and has not been continuously developed due to World War II and the discovery of large-scale natural gas, but mainly in Russia, the United States, Canada and the United Kingdom. Basic experimental research and field application tests have been carried out, and recently, commercial model plants have been operated in Russia and Australia, focusing on the development of clean fossil energy sources for air pollution, global warming, and oil depletion.

Most of the current underground coal gasification technology drills two holes to underground coal deposits, and injects an oxidant into one hole, and the gas produced by burning coal layer through electrical or chemical ignition is extracted from the other hole to the ground. That's how. At this time, depending on the oxidant injection / diffusion direction and the flame (combustion) progress direction, it is divided into reverse combustion method and forward combustion method, and most commercially adopt reverse combustion method.

However, the combustion method of the underground coal seam has a sudden rise in temperature due to spontaneous combustion that cannot be controlled after ignition alone due to the inaccessibility of the underground combustion surface, and the internal explosion, ground subsidence or water pollution, and toxic gas in case of emergency. Economic problems such as environmental problems such as spills and huge loss of energy resources are inherent.

The object of the present invention is to solve the problems of the traditional mining process for coal utilization, and to solve the uncontrollable problems arising from the underground coal gasification process by existing combustion, coal pile piles of several tens to thousands of meters underground. Alternatively, there is provided a method and apparatus for extracting an effective gas by thermally decomposing coal with microwave energy and minimal oxidant with little energy transfer loss to the seam, easy to control, and having selective heating characteristics of coal only.

The invention according to claim 1 is a gasification method of underground coal seam, comprising: supplying at least one microwave to the underground coal seam or pile (S1); And collecting the gas generated from the underground coal layer or the dummy 12 by the supplied microwave (S2), wherein the microwave has an ISM (Industry of the wavelength band of 1 cm to 1 m in the frequency band of 300 MHz to 30 GHz). , Science, Medicine) at least one microwave of frequency. In addition, in the step (S1) of supplying the microwave, an oxidant is further supplied to the underground coal layer in addition to the microwave, and the underground coal layer between the injection tube 30 and the extraction tube 40 is cracked to provide the injection tube 30 and The step of securing an initial fluid flow passage (S1 ') between the extraction tube 40, wherein the initial fluid flow passage securing step (S1') is performed before or after the microwave supply step (S1). .

According to the gasification method of the underground coal seam of claim 1, there is almost no energy transfer loss to the seam or pile of several tens to thousands of meters, it is easy to control, and the selective heating characteristic of selectively heating only coal is provided. By using the microwave energy, it can solve the environmental problems such as sudden temperature rise due to uncontrollable spontaneous combustion due to inaccessibility of the underground combustion surface, resulting in internal explosion, ground subsidence or water pollution, and toxic gas leakage. It can utilize the effective energy source without loss. And since the reaction is incomplete combustion by the oxidant supplied to the coal bed, by initiating or promoting the initial thermal decomposition, it is possible to perform the gasification of the coal bed more rest. In addition, a fluid flow passage is secured between the injection pipe 30 and the extraction pipe 40 to reduce the amount of gas leaking to another place, it is possible to extract the gas through the extraction pipe 40 more efficiently.

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The invention of claim 3 is the method of gasification of the underground coal seam of claim 1, comprising: purifying the collected off-gas and separating CO ₂ from the off-gas (S3); Converting the purified gas into an energy source (S4); And recycling the CO ₂ to the oxidant (S5).

According to the gasification method of claim of claim 3 underground coal seam, the underground gasification of coal can be utilized as an effective energy source, it is possible to recycle CO _2, it is possible to reduce the cost of gas production.

The invention according to claim 4 is the gasification method of the underground coal seam of claim 1, wherein the microwaves are supplied to the underground coal seam through an injection pipe 30 penetrated from the ground 10 to the underground coal seam or pile 12. The product gas is collected through a radially arranged extraction tube 40 positioned a certain distance away from the injection tube 30.

According to the gasification method of the underground coal bed of claim 4, since the generated gas is collected through the extraction pipe 40 provided separately from the microwave injection pipe 30, the gas collection can be made more efficiently, in particular the extraction pipe 40 It is arrange | positioned radially and can collect the gas produced | generated in underground coal seam efficiently.

The invention of claim 5 is the gasification method of the underground coal seam of claim 4, wherein the collection of the generated gas generated from the underground coal seam is made through the injection pipe 30, the injection pipe 30 is an insulator ( It is a waveguide type coaxial transmission line without using Dielectric Insulator.

According to the gasification method of the underground coal bed of claim 5, since the injection of microwaves and the collection of the generated gas can be made through one tube, that is, the injection pipe 30, the installation of the facility is simple and the installation cost can be reduced.

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The invention according to claim 7 is the gasification method of the underground coal layer according to any one of claims 1 and 3 to 6, wherein a microwave absorption initiator (Susceptor or Sensitizer) is used for the underground coal layer.

According to the gasification method of the underground coal seam of claim 7, the degree of absorption of microwaves is lower even in the case of underground coal of less than bituminous coal such as peat or lignite, which has a very low degree of carbonization (C / H ratio) and hardly absorbs microwaves. This can increase the gasification of the underground coal seam.

The invention of claim 8 is a gasification method of the underground coal seam of claim 7, wherein the microwave absorption initiator is pyrolysis (thermal decomposition).

According to the gasification method of the underground coal bed according to claim 8, since the absorption rate of microwaves can be increased by adding a small amount of thermally decomposed self-material, the carbonization rate (C / H ratio) is easily low without using a separate heterogeneous microwave absorption initiator. The coal seam can be gasified.

The invention according to claim 9 is a gasification apparatus (1) for underground coal seams, comprising: a microwave generator (2) for generating microwaves; A supply unit (3) for supplying the microwave, or the microwave and the oxidant to the underground coal layer or the heap (12); And an extraction unit 4 for extracting the gas generated from the underground coal layer or the heap 12 by the microwaves. Here, the supply unit 3 is installed so as to penetrate the underground coal layer or pile 12 from the ground (10), the injection pipe 30 for injecting the microwave into the underground coal layer; And a plurality of microwave dispersion slots 32 formed in the lower portion of the injection tube 30 to disperse the microwaves in the underground turbid layer or the dummy 12, wherein the microwave generator 2 includes the microwave generator 2. A microwave generator 21 for generating microwaves; A control device 20 connected to the microwave generator 21; And a microwave induction conductor tube 22 connecting the microwave generator 21 and the supply part 3, and the microwave induction conductor tube 22 includes a microwave induction conductor tube 24 therein.

According to the gasification apparatus 1 of the underground coal seam of claim 9, there is little energy transfer loss to the coal seam or the pile of several tens to thousands of meters, easy to control, and selective to selectively heat only coal. By using microwave energy with heating characteristics, it solves environmental problems such as sudden temperature rise due to uncontrolled spontaneous combustion due to inaccessibility of underground combustion surface, resulting in internal explosion, ground sediment or water pollution, and toxic gas leakage. An effective energy source can be utilized without loss of energy source. In addition, the microwave generated in the microwave generator descends through the injection pipe 30 to reach the underground coal layer or pile 12, and is absorbed by the surrounding coal layer through the microwave dispersion slot 32 to thermally decompose coal to Gasification proceeds. In addition, by the controller 20, the frequency of the microwave can be controlled according to the conditions of the coal seam in the microwave, the microwave thus controlled is supplied to the supply unit 3 through the microwave inlet conductive pipe 22 to gasify the underground coal bed It is possible to achieve, and since the transmission of the microwave is made through the double conduction tube, it can be delivered to the supply (3) without any microwave leakage.

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According to a twelfth aspect of the present invention, there is provided a gasification apparatus (1) for underground coal seams (10), and an automatic impedance matching controller (23) is provided in the microwave induction conductive pipe (22).

According to the gasification apparatus 1 of the underground coal seam of claim 12, the magnetron head in the microwave generator 21 can be protected by the automatic impedance matching controller 23, so that the life of the equipment can be maintained longer. have.

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The invention according to claim 14 is the gasifier of the underground coal seam (1) of claim 9, wherein the injection pipe (30) has an internal injection pipe (33) therein, and the internal injection pipe (33) is above ground. It consists of a ground inner injection pipe 34 is installed in the basement and the inner injection pipe 31 is installed underground, the oxidant injected through the above ground internal injection pipe 34 is the underground internal injection pipe 31 ) Is supplied to the cavity 34 of the underlying rock layer 13 below the underground coal bed or pile 12.

According to the gasification apparatus 1 of the underground coal bed according to claim 14, as the oxidant is supplied to the underground coal bed or the dummy 12 through the internal injection pipe 33, the exothermic coal causes partial oxidation reaction. In addition to producing syngas, microwave energy is transmitted not only along the inner surface of the injection tube 30 but also along the inner surface of the inner injection tube 33. It can deliver, and efficiency can be improved.

15. The invention according to claim 15 is the gasification apparatus 1 of the underground coal seam of claim 14, wherein the first choke section 25 is provided with an impedance matching sliding sealing device 27 (sliding seal) on the upper portion of the injection pipe 30. ) Is installed.

According to the gasification apparatus 1 of the underground coal seam of Claim 15, it is possible to flow all the microwave energy drawn into the underground coal seam without any microwave leakage by the first choke part 25 into the above-ground internal injection pipe 34. .

The invention according to claim 16 is the gasification apparatus 1 of the underground coal seam of claim 15, wherein the injection pipe 30 is a waveguide type coaxial transmission line that does not use a dielectric insulator, and the injection pipe 30 A second choke portion 28 having an impedance matching sliding sealing device is installed on one side of the upper end thereof, and a first gas pipe 29 is installed in the second choke portion 28, and the first choke portion ( When 25) is shorted, the second choke portion 28 is also shorted.

According to the gasification apparatus 1 of the underground coal seam of Claim 16, the microwave is carried out to the underground coal seam without any microwave leakage through the 1st gas pipe 29 used as a pipe which extracts the gas produced as needed, or puts an oxidizing agent. Can transfer energy.

The invention according to claim 17 is the gasification apparatus 1 for underground coal seams of claim 9, wherein the extraction unit 4 extracts a gas generated from the underground coal seam or pile 12 to the ground 10. 40; An extraction pipe lower suction filter 41 formed below the extraction pipe 40 to suck the generated gas generated from the underground coal layer or the dummy 12 into the extraction pipe 40; And a second gas pipe 42 installed at an upper portion of the extraction pipe 40 to discharge the generated gas flowing through the extraction pipe 40 to the ground.

According to the gasification apparatus 1 of the underground coal seam of claim 17, the gas generated from the underground coal seam or the heap 12 is filtered through the suction filter 41 so that only the mixed gas is removed from the ground through the extraction pipe 40. 2 can be extracted into the gas pipe 42 and then used as alternative energy through energy conversion and the like.

The invention of claim 18 is a gasifier of the underground coal seam (1) of claim 17, further comprising a refining device (50) connected to the second gas pipe (42) for purifying the product gas.

According to claim 18, claim gasification of underground coal bed apparatus 1, the mixed gas, CO + H _2, H ₂ O, CO _2, CH _4, H ₂ S is a purification apparatus (50) produced by the thermal decomposition of coal It can be refined and used in high purity so that higher efficiency can be obtained when converted to the required energy source through the energy conversion device.

Claim invention nineteenth claim is, wherein the gasification unit (1) of claim 18, claim underground coal beds, CO ₂ for separating the CO ₂ from the first connector purified gas is connected via 52 to the purifier 50 The separator 60 further includes a second connecting pipe 62 connecting the separator 60 and the supply part 3 to recycle the separated CO ₂ to the supply part 3.

According to the gasifier of the underground coal seam 1 of claim 19, the CO ₂ concentrated by the separator 60 is mixed with another oxidant and supplied through the internal injection pipes 31 and 34 of the injection pipe 30. Can be recycled. Therefore, the effect of resource saving, cost reduction, pollution prevention and the like can be obtained.

The invention according to claim 20 is a gasification apparatus (1) of underground coal beds according to claims 9 to 12 and 14 to 19, and the extracted gas connected to the extraction unit (4) and supplied is required. The apparatus further includes an energy source conversion device 70 for converting the energy source.

According to the gasification apparatus 1 of the underground coal seam of claim 20, since the coal resources of the underground coal seam can be gasified and converted into actual energy sources, the blue coal fossil energy source used for air pollution, global warming, oil depletion, etc. Can be.

According to the gasification method and gasification apparatus (1) of underground coal seams according to the present invention, there is almost no energy transmission loss to coal beds or piles of several tens to thousands of meters underground, easy to control, and microwave having selective heating characteristics only for coal. The energy can be used to pyrolyze coal to extract the effective gas.

Therefore, according to the present invention, existing problems for the utilization of underground coal, namely, sudden temperature rise due to uncontrollable spontaneous combustion after germination, resulting in internal explosion, ground sedimentation or water pollution, and toxic gas leakage in emergency It can solve environmental problems, economic problems, etc., and secure clean alternative energy sources.

1 is a schematic view showing a gasifier 1 of underground coal seams according to an embodiment of the present invention.
Figure 2 is a graph showing the changes in the components of the domestic anthracite coal pyrolysis gas over time.
3 is a graph comparing the microwave absorption rate according to the type of coal.
4 is a graph showing the microwave absorption characteristics according to the degree of carbonization (C / H ratio).
5 is a graph showing the microwave absorption characteristics according to the mixing ratio of the self-initiator.

Hereinafter, the present invention will be described more specifically.

Gasification method of the underground coal bed according to an embodiment of the present invention, the step of supplying at least one microwave to the underground coal bed or pile 12 (S1); And collecting the gas generated from the underground coal layer or the dummy 12 by the supplied microwave (S2), wherein the microwave has an ISM (Industry of the wavelength band of 1 cm to 1 m in the frequency band of 300 MHz to 30 GHz). , Science, Medicine) at least one microwave of the frequency. Microwaves of this frequency are selectively absorbed by the underground coal itself to pyrolyze the coal. Microwave dielectric heating (Dielectric Heating) using the microwave is a method using the intermolecular friction energy due to the rotation (Dipole Rotation) or the realignment of the molecules constituting the material in the electromagnetic field. Therefore, the gasification method of the underground coal bed using the microwave of the present invention can be thermally decomposed or incompletely burned by selectively heating only coal without selectively igniting and burning process, so that not only emergency operation control but also the desired product gas composition can be easily controlled. have.

According to an embodiment of the present invention, the microwave may be supplied together with an oxidizing agent in addition to the microwave. When the oxidant diffuses into the underground coal bed, the exothermic coal undergoes a partial oxidation reaction, producing syngas (CO + H ₂ ) as the main component. As coal is pyrolyzed by the supplied microwave energy or syngas is produced by partial oxidation, the coal eventually leaves only ash components, and the surrounding coal layer becomes semi-transparence or transparent to the microwaves. As it travels further and further, there is a continuous gasification of the coal seam.

According to one embodiment of the invention, the step of purifying the collected product gas and separating the CO ₂ from the product gas (S3); Converting the purified gas into an energy source (S4); And recycling the CO ₂ to the oxidant (S5).

The collected product gas is composed of steam (H ₂ O), CO ₂ , CH ₄ , H ₂ S, etc. in addition to the synthesis gas (CO + H ₂ ) as a main component, the heat exchange / CO with the syngas purification device 50 After passing through the _second separation unit 60, it can be converted into the necessary energy resources through the coal combined cycle (IGCC) plant 51, FT synthesis reactor 61 for coal liquefaction (CTL) and the like can be used. In addition, the CO ₂ gas concentrated in the CO ₂ separator 60 is mixed with another oxidant to form the bottom of the coal layer 12 along the ground internal injection pipe 34 and the underground internal injection pipe 31 of the injection pipe 30. Can be recycled to the cavity 34 (cavity).

According to an embodiment of the present invention, the injection tube 30 of the microwave injection unit may use both a coaxial transmission line or a waveguide, and has a structure capable of simultaneously transmitting microwaves and a predetermined amount of oxidant to a coal bed. It is. That is, as shown in FIG. 1, the microwave is supplied to the underground coal layer through the injection pipe 30 penetrated from the ground 10 to the underground coal layer or the pile 12, and the gas generated by the microwave is injected into the injection tube ( 30 is collected via a radially arranged extraction tube 40 located a distance away from it.

However, according to one embodiment of the present invention, in the case of the waveguide type coaxial transmission line that does not use an dielectric (Dielectric Insulator) through the injection pipe 30 without installing the product gas extraction pipe 40 separately The ground 10 may be extracted and collected through the first gas pipe 29.

According to an embodiment of the present invention, by cracking the underground coal layer between the injection pipe 30 and the extraction pipe 40 to secure the initial fluid flow path between the injection pipe 30 and the extraction pipe 40 It further comprises a step S1 ', wherein the initial fluid flow passage securing step S1' is performed before or after the microwave supplying step S1. The cracking method may be performed using a method generally known in the art, and various methods such as, for example, hydraulic fracturing or ground explosion may be used. The gas generated by the gasification of the underground coal bed by this cracking method flows down the extraction pipe 40 along the diffusion passage of the underground coal bed through the suction filter 41 and the extraction pipe 40. 42).

According to an embodiment of the present invention, a microwave absorption initiator (Susceptor or Sensitizer) may be further supplied to the underground coal seam. As the microwave absorption initiator to increase the absorption rate of the microwave, pyrolyzed internal materials or heterogeneous materials (Fe 2 O 3, SiC, etc.) may be used. The self-initiator, which is a thermally decomposed self material according to the present invention, has a carbonization degree (C / H ratio) of 2.7 or more and may be used in an amount of 4 to 6 wt.% Based on the total amount of coal. If the content of the self-initiator is less than 4wt.%, The effect of the self-initiator is insignificant and the addition of more than 6wt.% Does not significantly increase the absorption rate of the microwave. When the microwave absorption initiator is used according to the present invention, even when the bituminous coal below the bituminous coal level such as peat or lignite, which has very low carbonization (C / H ratio), absorbs microwaves, It can be increased to gasify underground coal seams.

Hereinafter, the present invention will be described in more detail with reference to the drawings. However, this is to explain the present invention in more detail, the present invention is not limited thereto. In addition, Figure 1 is a schematic diagram according to an embodiment of the present invention, as long as the configuration having a function shown in the present invention may be in any form.

Referring to FIG. 1, the gasification apparatus 1 for underground coal seams according to an embodiment of the present invention includes a microwave generator 2 for generating microwaves; A supply unit (3) for supplying the microwave, or the microwave and the oxidant to the underground coal layer or the heap (12); And an extraction unit 4 for extracting the gas generated from the underground coal layer or the heap 12 by the microwaves.

The microwave generator 2 includes a microwave generator 21 for generating the microwaves; A control device 20 connected to the microwave generator 21; And a microwave induction conductor 22 connecting the microwave generator 21 and the supply part 3 to each other.

The microwave inlet conduit 22 includes a microwave inlet inner conduit 24 therein. An automatic impedance matching control device 23 is installed in the microwave induction conductive pipe 22 to protect the magnetron head in the microwave generator 21, so that the life of the equipment can be maintained longer.

The power supply and control device 20 installed on the ground 10 allows the microwave generator 21 to change the frequency of the microwave depending on the conditions of the coal seam, but here mainly for the generation of an ISM frequency of 2450 MHz or 915 MHz or 460 MHz. It works. Of course, other frequencies are also available depending on the particular installation conditions. Generated microwaves of a specific frequency determined by underground coal gasification conditions are connected to the inlet outlet 30 on the ground via an inlet outer conductor 22 containing an inlet inner conductor 24 above the ground. do. In this case, an automatic impedance matching control device 23 is installed in the microwave introducing internal conductive tube 24 to protect the magnetron head in the microwave generator 21 from being damaged by the reflected power of the microwave transmitted to the injection tube 30. do.

The supply unit 3, the injection pipe 30 is installed so as to completely penetrate the underground coal layer or pile 12 located at the bottom of the aquifer layer 11 from the ground 10, and injects the microwave into the underground coal layer; And a plurality of microwave dispersion slots 32 formed in the lower portion of the injection tube 30 to disperse the microwaves in the underground turbid layer or the dummy 12.

The injection pipe 30 may use both a coaxial transmission line or a waveguide, and has a structure capable of simultaneously sending microwaves and a predetermined amount of oxidant to a coal bed.

According to an embodiment of the present invention, in the case of the waveguide type coaxial transmission line in which the injection tube 30 does not use a dielectric insulator, a plurality of microwave dispersions are not provided without installing the product gas extraction tube 40 separately. The product gas is extracted through the slot, and the product gas is extracted to the ground 10 through the first gas pipe 29.

According to another embodiment of the present invention, in the case of the microwave coaxial transmission line in which the injection tube 30 uses an insulation, it is impossible to extract the generated gas through its own coaxial line, so that multiple radial shapes are generated at a predetermined distance. The product gas is extracted to the ground 10 through the second gas pipe 42 communicating with the gas extraction pipe 40.

According to an embodiment of the present invention, the first gas pipe 29 is connected to the second gas pipe 42 of the extraction part 4, which is installed separately from the supply part 3, and collected through the first gas pipe 29. The generated gas and the generated gas collected through the second gas pipe 42 may be collected and supplied to the refining device 50 and / or the separating device 60.

The microwave dispersion slot 32 (slot array) is formed at the lower end of the injection pipe 30, that is, the lower end of the injection pipe 30 penetrating the underground coal layer or pile 12, for example, alumina (Al ₂ O ₃ ) may be formed as a ceramic filter to disperse the microwaves flowing along the injection pipe 30 in the underground coal layer, or may function as an inlet for sucking gas generated by thermal decomposition of the underground coal.

According to an embodiment of the present invention, the injection pipe 30 has an internal injection pipe 33 therein, the internal injection pipe 33 and the ground internal injection pipe 34 is installed on the ground and It is composed of an underground internal injection pipe 31 is installed underground, the oxidant injected through the above ground internal injection pipe 34 is located along the underground internal injection pipe 31 of the underground coal layer or pile 12 It is supplied to a cavity 34 of the base rock layer 13.

Therefore, the microwave energy goes down between the inner surface (Outer Conductor) of the injection tube 30 and the inner surface (Inner Conductor) of the inner injection tube 31, through the numerous micro dispersion slots 32 to the underground coal bed Is investigated. The irradiated microwave energy is absorbed by the coal layer around the microwave dispersion slot 32 to cause high temperature heat of the coal itself to pyrolysis the coal. On the other hand, the oxidant supplied to the cavity 34 (cavity) around the base rock layer 13 below the coal layer 12 along the ground oxidant injection hole 26 is diffused to produce syngas which is a main component as the exothermic coal causes partial oxidation reaction. . When coal is pyrolyzed by the supplied microwave energy or syngas is produced by a partial oxidation reaction, coal remains only ash components, and the surrounding coal layer becomes semi-transparence or transparent to microwaves. Propagates further and further the continuous gasification of the coal seam.

According to an embodiment of the present invention, the first choke portion 25 having the impedance matching sliding sealing device 27 (sliding seal) is installed on the injection pipe 30. The impedance matching sliding sealing device 27 is impedance matched to a length of 1/4 wavelength of the applied frequency, and is introduced without any microwave leakage to the oxidant injection pipe 26 connected to the upper internal injection pipe 34. All microwave energy flows down the injection tube 30, ie underground coal bed.

According to an embodiment of the present invention, the injection tube 30 is a waveguide type coaxial transmission line that does not use a dielectric insulator, and an impedance matching sliding sealing device (not shown) on one side of the upper end of the injection tube 30. Second choke portion 28 is installed, and a first gas pipe 29 is installed in the second choke portion 28, and the second choke portion 25 is shorted when the second choke portion 25 is shorted. The choke 28 is also short-circuited.

The second choke portion 28 also has an impedance matching sealing device of the same structure having a length of 1/4 wavelength of the applied frequency, so that no microwave leakage occurs. In particular, in the case where the injection pipe 30 is a waveguide type coaxial line without using insulation, the first gas pipe 29 connected to the second choke part 28 without installing the product gas extracting part 40 separately is provided. Underground coal gasification products can be extracted. The first gas pipe 29 has an advantage that it can also be used as the injection port of the other oxidant gas when the product gas extraction unit 40 is installed separately.

The extraction unit 4 is an extraction pipe 40 for extracting the gas generated from the underground coal layer or pile 12 to the ground (10); An extraction pipe lower suction filter 41 formed below the extraction pipe 40 to suck the generated gas generated from the underground coal layer or the dummy 12 into the extraction pipe 40; And a second gas pipe 42 installed at an upper portion of the extraction pipe 40 to discharge the generated gas flowing through the extraction pipe 40 to the ground.

The extraction pipe 40 is installed so as to penetrate the underground coal layer or pile 12 from the ground 10, it is possible to extract the gas generated from the underground coal layer directly to the ground (10). Since the extraction tube may be manufactured and installed by methods and materials known in the art, a detailed description thereof will be omitted.

The suction filter 41 is formed at the lower end of the extraction tube 40, that is, the lower end of the extraction tube 40 located in the underground coal layer 12, and ash or coal remaining after reacting the gas generated from the underground coal layer. In addition to water, only the product gas is configured to pass.

The second gas pipe 42 collects the generated gas flowing through the extraction pipe 40, and the second gas pipe 42 is connected to the first gas pipe 29 or alone may be a plurality of purification devices ( 50, in turn or in direct connection to the separator 60 or energy converters 70, so that the gas produced from the underground coal seam can be used as alternative energy on the ground 10.

The gas produced by the thermal decomposition of coal is composed of CO + H ₂ , H ₂ O, CO ₂ , CH ₄ , H ₂ S and the like as a mixed gas, which can be purified by the purification device 50.

The purified gas is further separated from the CO ₂ through a separator 60 connected to the purifier 50 through a first connecting pipe 52. The separated CO ₂ is recycled as an oxidant through a second connecting pipe 62 connected to the supply part 3.

In addition, the purified and / or CO 2 separated gas is required energy resources via an energy conversion device 70 such as a coal combined cycle (IGCC) plant 71 or an FT synthesis reactor 72 for coal liquefaction (CTL). Is switched to.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 (Microwave Pyrolysis Gasification of Domestic Anthracite Coal)

In the experiment of domestic anthracite coal gasification by microwave in a 0.75 ”circulating quartz tube reactor with a nitrogen atmosphere, the produced gases were mainly H _{2 ,} CO, CO ₂ , CH ₄ , and components. This indicates that the raw coal (KAC) absorbs the microwaves incident through the quartz tube and rapidly heats itself so that the water and volatile components present in the coal react or decompose with the substrate carbon according to the following microwave pyrolysis reaction.

Figure 2 is a graph showing the composition change of the product gas with the irradiation time when the 2.45GHz microwave incident power is 800watts (20g, N ₂ ). According to this, the generated CO ₂ and CH ₄ are recycled after about 10 minutes of microwave irradiation, and are respectively decomposed into CO and H ₂ by the following pyrolysis reaction equation, and finally, a synthesis gas having an H ₂ / CO ratio of about 1.3 can be obtained. Can be.

Example 2 (Microwave Absorption Characteristics According to Type of Coal)

When the microwave incident power is 500watts, the unit weight and the microwave absorption rate per volume for various carbonaceous materials were measured under the same conditions as the experimental apparatus and method of Example 1, and the results are shown in FIG. 3. From FIG. 3, microwave absorption rates of domestic anthracite samples (KAK-A2, KAM-A1) and porous commercial activated carbon samples (Calg-w1, FMC-char) with high carbonization (C / H ratio) are very high, while the carbonization is low. In China, Dongfangtan (CAD-A1, sub-bituminous coal) and Indonesian Rototan (IAR-A1, lignite) show very low microwave absorption, especially in the same carbon, porous samples have higher microwave absorption. seen from point, the US Calgon Corporation sample ^{(Calg-w1, 800m 2 /} g) processing the porous commercial activated carbon with and FMC Corporation sample ^{(FMC-char, 62m 2 /} g) and approximately equal to or higher per unit volume of the microwave absorption rate The domestic anthracite coal (2-5m ² / g) as raw coal is shown to be more advantageous to underground coal gasification using the rapid self-heating characteristics by microwave.

Example 3 (Gasification Method Using Self-susceptor)

In the same way as in Example 2, the carbon (C / H ratio) is very low, and the bituminous coals (CAD-A1, IAR-A1) of sub-bituminous grades, such as peat or lignite, which hardly absorb microwaves. In order to confirm whether the absorption characteristics by microwaves can be increased by the magnetic initiator, the microwave absorption rate was measured using a rice hull having a lower C / H ratio than peat.

Figure 4 is a graph showing the measurement of the micro-absorption rate according to the C / H molar ratio as a self-initiator (microwave absorption characteristics according to the mixing ratio of thermal carbonized chaff and raw rice husk). According to this, the possibility of continuous microwave carbonization was confirmed when mixing the C / H molar ratio of 2.7 or more.

Figure 5 shows the graph by measuring the microwave absorption rate while changing the content of the magnetic initiator, it can be seen that the microwave absorption rate according to the mixing ratio of the magnetic initiator. Therefore, the minimum mixing ratio of the self-initiator required for underground coal gasification can be known from this.

That is, as can be seen from Figure 4, the microwave absorption rate of the carbonaceous bulk material having a low C / H ratio was increased as the C / H ratio was increased to more than 2.7, the mixing ratio of the carbonized self-initiator, but more than 6wt.% In this case, since it has a substantially constant value, it can be seen that the minimum mixing ratio of the self-initiator for gasification of the continuous underground coal seam is within about 6 wt.%.

Accordingly, it can be seen from the above embodiment that the gas can be gasified by microwaves, and even in the case of peat and the like having low microwave absorption rate, gas can be sufficiently gasified by a microwave absorption initiator such as a magnetic initiator.

1: Gasifier of underground coal seam 2: Microwave generator
3: supply part 4: extraction part
10: ground 11: aquifer
12: coal seam or pile 13: based rock bed
14: Cavitiy
20: refinery device, power device 21: microwave generator
22: microwave induction conductor 23: automatic impedance matching controller
24: microwave entry inner conductor
25: First choke section
27: impedance matching sliding seal
28: second choke part 29: first gas pipe
30: injection tube 32: microwave dispersion slot
33: internal injection tube 31: underground internal injection tube
34: ground internal injection tube
40: extraction tube 41: suction filter
42: second gas pipe
50: refiner 52: first connector
60: separator 62: second connector
70: energy conversion device

Claims (20)

Supplying at least one microwave to the underground coal bed or pile 12 (S1); And collecting the gas generated from the underground coal bed or the heap 12 by the supplied microwave (S2),
The microwave is at least one microwave of the ISM (Industry, Science, Medicine) frequency of the wavelength band of 1cm ~ 1m of the frequency band of 300Mhz ~ 30GHz,
In step S1 of supplying the microwave, an oxidizing agent is further supplied to the underground coal layer in addition to the microwave,
And cracking the underground coal layer between the injection pipe 30 and the extraction pipe 40 to secure an initial fluid flow path between the injection pipe 30 and the extraction pipe 40 (S1 '). And the initial fluid flow passage securing step (S1 ') is performed before or after the microwave supplying step (S1). delete The method of claim 1,
Purifying the collected off-gas and separating CO ₂ from the off-gas (S3);
Converting the purified gas into an energy source (S4); And
Recycling the CO ₂ to the oxidizing agent (S5) further comprising the gasification method of the underground coal bed. The method of claim 1,
The microwave is supplied to the underground coal layer through the injection pipe 30 penetrated from the ground 10 to the underground coal layer or pile 12,
The product gas is a gasification method of the underground coal seam, characterized in that collected through the radially arranged extraction pipe 40 located a certain distance away from the injection pipe (30). 5. The method of claim 4,
Collection of the generated gas generated from the underground coal bed is made through the injection pipe 30,
The injection pipe (30) is a gasification method of underground coal seams, characterized in that the waveguide type coaxial transmission line using no insulator (Dielectric Insulator). delete 6. The method according to any one of claims 1 to 5,
Microwave absorption initiator (Susceptor or Sensitizer) is used for the underground coal bed gasification method of the underground coal bed. The method of claim 7, wherein
The microwave absorption initiator is a method of gasification of the underground coal seam, characterized in that the pyrolysis (thermal decomposition) material. A microwave generator 2 for generating microwaves; A supply unit (3) for supplying the microwave, or the microwave and the oxidant to the underground coal layer or the heap (12); And an extraction unit 4 for extracting the gas generated from the underground coal layer or the pile 12 by the microwaves,
The supply unit 3 is installed to penetrate the underground coal layer or pile 12 from the ground (10), the injection pipe 30 for injecting the microwave into the underground coal layer; And a plurality of microwave dispersion slots 32 formed in the lower portion of the injection tube 30 so that the microwaves are dispersed in the underground turbidity layer or the dummy 12.
The microwave generator 2 includes a microwave generator 21 for generating the microwaves; A control device 20 connected to the microwave generator 21; And a microwave induction conductor tube 22 connecting the microwave generator 21 and the supply part 3, wherein the microwave induction conductor tube 22 includes a microwave inlet conductor tube 24 therein. Gasification device of underground coal seam to be. delete delete 10. The method of claim 9,
The microwave incoming conductive pipe (22) is a gasifier of the underground coal bed, characterized in that the automatic impedance matching control device (23) is provided. delete 10. The method of claim 9,
The injection tube 30 has an internal injection tube 33 therein,
The internal injection pipe 33 is composed of the above-ground internal injection pipe 34 is installed on the ground and the underground internal injection pipe 31 is installed in the base, the injection through the above ground internal injection pipe 34 An apparatus for gasification of underground coal seams, characterized in that an oxidant is supplied to the cavity (34, cavity) of the underground coal seam or base rock layer (13) below the pile (12) along the underground internal injection pipe (31). 15. The method of claim 14,
The gasifier of the underground coal seam, characterized in that the first choke portion (25) having an impedance matching sliding sealing device (27, Sliding Seal) is installed on the injection pipe (30). 16. The method of claim 15,
The injection tube 30 is a waveguide type coaxial transmission line that does not use a dielectric insulator,
A second choke part 28 having an impedance matching sliding sealing device is installed on one side of the upper end of the injection pipe 30, and a first gas pipe 29 is installed in the second choke part 28.
The second choke part (28) is also short-circuited when the first choke part (25) is shorted. 10. The method of claim 9,
The extraction unit 4 is an extraction pipe 40 for extracting the gas generated from the underground coal layer or pile 12 to the ground (10);
An extraction pipe lower suction filter 41 formed below the extraction pipe 40 to suck the generated gas generated from the underground coal layer or the dummy 12 into the extraction pipe 40; And
The gasifier of the underground coal bed, characterized in that it comprises a second gas pipe (42) installed on the upper portion of the extraction pipe (40) for discharging the generated gas flowing through the extraction pipe (40) to the ground. 18. The method of claim 17,
The gasifier of the underground coal bed further comprises a purifier (50) connected to the second gas pipe (42) to purify the generated gas. 19. The method of claim 18,
A CO ₂ separation device 60 connected to the refining device 50 through a first connection pipe 52 to separate CO ₂ from the purified gas; And
The gasifier of the underground coal bed further comprises a second connecting pipe 62 for connecting the separator 60 and the supply part 3 to recycle the separated CO ₂ to the supply part 3. . The method according to any one of claims 9, 12, 14-19,
An apparatus for gasification of underground coal beds, further comprising an energy source switching device (70) connected to the extraction unit (4) to convert the extracted gas into a required energy source.

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