Coal in-situ pyrolysis hydrogen production device and method

Abstract

The present application belongs to the technical field of coal hydrogen production, and specifically discloses a coal underground in-situ pyrolysis hydrogen production device and method. The device comprises an injection well, a production well and a gas conversion production well vertically arranged in a coal seam. The depths of the production well and the injection well are both greater than that of the gas conversion production well. The gas conversion production well is composed of two vertical wells and a horizontal well connected at the bottom of the two vertical wells. A methanation catalyst filling layer is arranged in the horizontal well. A first methane steam reforming catalyst filling layer is arranged in the middle of each of the two vertical wells. The gas outlets of the two vertical wells are connected with the gas inlets of a hydrogen separation device. The device can make pyrolysis gas gather at the top of the coal seam and liquid phase products gather at the bottom of the coal seam by improving the well arrangement mode, so as to avoid the pollution of tar to the catalyst in the gas conversion production well.

Description

Technical Field

[0001] This invention belongs to the field of coal-to-hydrogen technology, specifically relating to an underground in-situ pyrolysis hydrogen production device and method. Background Technology

[0002] Coal plays a crucial role in global economic development and technological innovation. For a long time, coal has accounted for a huge proportion of global energy consumption, making it the mainstay of global energy consumption. In recent years, although the proportion of coal resources in global primary energy consumption has declined somewhat due to increased global attention to environmental issues and the development of various new energy technologies, it still accounts for more than 25%. However, it should be noted that the large-scale utilization of coal resources has generated a series of environmental problems such as air pollution and the greenhouse effect, which are inconsistent with the requirements of today's sustainable development. Therefore, the development of high-quality clean coal utilization technologies is urgently needed.

[0003] Underground in-situ coal pyrolysis technology refers to the process of directly heating underground coal seams by introducing heat into them. After the solid organic matter in the coal is pyrolyzed by heat, the resulting coal tar and pyrolysis gas are extracted to the surface. Through underground in-situ coal pyrolysis, the carbon in the coal can be converted into low-carbon or carbon-free resources such as methane and hydrogen, while the semi-coke remains underground. This not only achieves efficient and low-carbon utilization of coal but also greatly extends the depth range of coal utilization.

[0004] Hydrogen energy is a renewable and clean energy source that can achieve zero emissions. Its combustion produces a calorific value of approximately 142.3 MJ / kg, several times that of the same mass of oil or gas. Furthermore, hydrogen is an important raw material in many chemical production processes, possessing significant utilization value. Realizing the conversion of coal into hydrogen can promote the diversified utilization of coal resources and has important practical significance.

[0005] Defects and shortcomings of existing technology:

[0006] Existing coal-to-hydrogen technology mainly involves mining, washing, and crushing coal, followed by thermochemical methods to produce hydrogen. Although some progress has been made in related research, there are still some significant shortcomings, such as excessive byproducts during the hydrogen production process, catalysts being easily contaminated and poisoned, losing their activity, and low hydrogen production efficiency. The hydrogen production process also suffers from high energy consumption, high operating costs, and high initial investment. Summary of the Invention

[0007] The purpose of this invention is to provide a coal underground in-situ pyrolysis hydrogen production device and method to solve the technical problems of numerous by-products, easy catalyst deactivation, and low hydrogen production efficiency in existing coal hydrogen production processes.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] In a first aspect, the present invention provides a coal underground in-situ pyrolysis hydrogen production device, comprising an injection well, a production well, and a gas shift production well vertically arranged in a coal seam. The depths of the production well and the injection well are both greater than those of the gas shift production well. The gas shift production well is located between the production well and the injection well. The gas shift production well includes two vertical wells, the bottoms of which are connected by a horizontal well. A methanation catalyst filling layer is provided in the horizontal well. A first methane steam reforming catalyst filling layer is provided in the middle of each of the two vertical wells. The gas outlets of the two vertical wells are connected to the gas inlet of a hydrogen separation device.

[0010] A further improvement of the present invention is that: a first insulation cotton layer is provided on the outer wall of each vertical well, the first insulation cotton layer and the vertical well form a first space, and the first space is filled with a heating medium.

[0011] A further improvement of the present invention is that a resistance wire layer and a second insulation cotton layer are sequentially provided on the outer side of the injection well inlet from the inside to the outside.

[0012] A further improvement of the present invention is that: the production well is provided with a gas production pipe and a liquid production pipe, the bottom of the liquid production pipe is provided with an oil pump, the outlet of the liquid production pipe is connected to the inlet of the liquid product collection device, and the outlet of the liquid product collection device is connected to the inlet of the centrifuge.

[0013] A further improvement of the present invention is that it also includes an air compressor, the air compressor having an air inlet that is supplied with air, the air compressor having an air outlet that is connected to the air inlet of a first flow meter, and the air outlet of the first flow meter being connected to the inlet of an injection well.

[0014] A further improvement of the present invention is that: the outlet of the hydrogen separation device is connected to the first inlet of the gas separation device, the hydrogen separation device is used to separate hydrogen from the pyrolysis gas discharged from the vertical well, the second inlet of the gas separation device is connected to the outlet of the gas production pipe, the first outlet of the gas separation device is connected to the inlet of the supercritical fluid generator, the outlet of the supercritical fluid generator is connected to the inlet of the injection well, and the second outlet of the gas separation device is connected to the inlet of the injection well.

[0015] Secondly, the present invention provides a coal underground in-situ pyrolysis hydrogen production device, comprising an injection well, a production well, and a gas shift production well vertically arranged in the coal seam. The depths of the production well and the injection well are both greater than those of the gas shift production well. The gas shift production well is located between the production well and the injection well. The gas shift production well includes two vertical wells, the bottoms of which are connected by a horizontal well. A second methane steam reforming catalyst packing layer is provided in the horizontal well. The gas outlets of the two vertical wells are connected to the gas inlet of a hydrogen separation device. The gas inlet of the injection well is connected to the gas outlet of a supercritical fluid generator. The supercritical fluid generator is used to provide supercritical carbon dioxide and supercritical superheated steam.

[0016] A further improvement of the present invention is that a CO2 adsorption material filling layer is provided on the outer side of the horizontal well.

[0017] Thirdly, the present invention provides a method for producing hydrogen through underground in-situ pyrolysis of coal, comprising the following steps:

[0018] Injection wells, production wells, and gas shift production wells are drilled in the coal seam. Fuel, igniter, proppant, and fracturing fluid are injected into the coal seam together. The production well is then closed, and inert gas is injected into the injection well to preheat the coal seam and ignite the igniter. Air or oxygen-enriched gas is then introduced into the injection well to continuously release heat from the combustion of the igniter and fuel, thus pyrolyzing the coal seam. The gaseous products generated by pyrolysis enter the gas shift production well. These gaseous products undergo methanation and methane steam reforming reactions sequentially with the methanation catalyst packing layer and the first methane steam reforming catalyst packing layer. Afterward, the gaseous products are extracted to the surface and separated into hydrogen by a hydrogen separation device. Once the hydrogen preparation is complete, the production well is opened, air injection is stopped, and purging gas is injected into the injection well to extract the pyrolysis gas remaining in the coal seam and the liquid products remaining at the bottom of the coal seam to the surface.

[0019] Fourthly, the present invention provides a method for producing hydrogen through underground in-situ pyrolysis of coal, comprising the following steps:

[0020] Injection wells, production wells, and gas shift production wells are drilled in the coal seam. Hydrogen production catalysts and proppant are injected into the coal seam along with fracturing fluid to create fractures. The production wells are then closed, and supercritical carbon dioxide or supercritical superheated steam is injected into the injection wells via a supercritical fluid generator. The coal in the seam undergoes pyrolysis under the combined action of supercritical carbon dioxide or supercritical superheated steam and the hydrogen production catalyst. The gaseous products generated by pyrolysis accumulate in the upper part of the coal seam and undergo methanation after passing through the second methane steam reforming catalyst packing layer. The methanated products are then extracted to the surface and separated into hydrogen by a hydrogen separation device. After hydrogen production is completed, the production wells are opened, air injection is stopped, and purging gas is injected into the injection wells to extract the pyrolysis gas remaining in the coal seam and the liquid products remaining at the bottom of the coal seam to the surface.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] This invention utilizes a method of simultaneously drilling injection and production wells in underground coal seams, along with a gas shift production well. This well is filled with methanation catalysts and methane steam reforming catalysts, or a thin-layer container is welded to the outer wall of the wellbore to fill it with CO2 adsorption material. This approach upgrades the gaseous products from pyrolysis to produce hydrogen, combining traditional hydrogen production methods with the realities of underground coal seam pyrolysis. The improved well layout utilizes gravity to cause pyrolysis gas to accumulate at the top of the coal seam, while liquid products accumulate at the bottom, preventing tar contamination of the catalyst in the gas shift production well. Furthermore, this invention employs externally supplied fuel or direct combustion of a portion of the coal with an igniter. The combustion aid uses controlled-temperature oxidative combustion, and supercritical steam and supercritical carbon dioxide are used to heat the coal seam. Combined with a hydrogen production catalyst, this catalytically modifies the pyrolysis process and its products, directing the coal pyrolysis products towards hydrogen production. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0024] In the attached diagram:

[0025] Figure 1 This is a schematic diagram of the structure of an underground in-situ coal pyrolysis hydrogen production device according to the present invention;

[0026] Figure 2 This is a partial enlarged view of the coal seam in an underground in-situ pyrolysis hydrogen production device of the present invention;

[0027] Figure 3 This is a schematic diagram of a second structure of a coal underground in-situ pyrolysis hydrogen production device according to the present invention;

[0028] Figure 4 This is a partially enlarged view of the second type of coal seam in an underground in-situ coal pyrolysis hydrogen production device of the present invention;

[0029] Figure 5 This is a schematic diagram of the structure of Example 5 of the underground in-situ pyrolysis hydrogen production device of the present invention;

[0030] Figure 6 This is a partial enlarged view of the coal seam in Example 5 of the coal underground in-situ pyrolysis hydrogen production device of the present invention;

[0031] In the diagram: 1. Coal seam roof; 2. Coal seam floor; 3. Coal seam; 4. Oil pump; 5. Production well; 6. Methanation catalyst packing layer; 7. Gas production pipe; 8. Coal seam combustion heating zone; 9. Injection well; 10. Gas shift production well; 101. Vertical well; 102. Horizontal well; 11. Screen pipe; 12. Heating medium; 13. First insulation cotton; 14. First methane steam reforming catalyst packing layer; 15. Air compressor; 16. First flow meter; 17. Heater; 18. Hydrogen separation device; 19. Gas separation device; 20. New energy power generation device; 21. Liquid phase product collection device; 22. Centrifuge; 23. CO2 adsorption material packing layer; 24. Second methane steam reforming catalyst packing layer; 25. Resistance wire; 26. Second insulation cotton; 27. Supercritical fluid generator; 28. Second flow meter. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0033] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0034] Example 1

[0035] An underground in-situ pyrolysis hydrogen production device for coal, such as Figure 1 and 2 As shown, it includes:

[0036] An injection well 9, a production well 5, and a gas shift production well 10 are vertically arranged within the coal seam 2. The depths of the production well 5 and the injection well 9 are greater than those of the gas shift production well 10. The gas shift production well 10 is located between the production well 5 and the injection well 9. The gas shift production well 10 includes two vertical wells 101, and the bottoms of the two vertical wells 101 are connected by a horizontal well 102. The horizontal well 102 is provided with a methanation catalyst filling layer 6. The middle of each of the two vertical wells 101 is provided with a first methane steam reforming catalyst filling layer 14. The gas outlets of the two vertical wells 101 are connected to the gas inlet of the hydrogen separation device 18.

[0037] Specifically, the hydrogen separation device 18 is used to separate and purify hydrogen in the extracted gas. It can use a PSA hydrogen separation device for pressure swing adsorption. The PSA device can be filled with one or more of the following: silica gel, alumina, molecular sieve, etc. Alternatively, hydrogen can be separated by selectively permeating a semipermeable membrane. The semipermeable membrane can be made of polymer membranes such as polysulfone, dimethylsiloxane, or polyimide.

[0038] Specifically, a first insulation cotton layer 13 is provided on the outer wall of the two vertical shafts 101, and a first space is formed between the first insulation cotton layer 13 and the outer wall of the vertical shaft 101, and the first space is filled with a heating medium 12.

[0039] Specifically, the outlet of the first space is connected to the inlet of the heater 17, and the outlet of the heater 17 is connected to the inlet of the first space, so that the heating medium 12 in the first space is heated by the heater 17.

[0040] Specifically, heater 17 is electrically connected to new energy power generation device 20, and new energy power generation device 20 supplies power to heater 17. The temperature of gas shift production well 10 is maintained above 600°C through heater 17 and heating medium 12, so that the methane steam reforming catalyst maintains high catalytic activity.

[0041] Specifically, a screen pipe (11) is fitted on the outside of the horizontal well (102).

[0042] Specifically, the outer side of the injection well 9 is provided with a resistance wire layer 25 and a second insulation cotton layer 26 from the inside to the outside.

[0043] Specifically, the production well 5 is equipped with a gas production pipe 7 and a liquid production pipe. The bottom of the liquid production pipe is equipped with an oil pump 4. The outlet of the liquid production pipe is connected to the inlet of the liquid product collection device 21, and the outlet of the liquid product collection device 21 is connected to the inlet of the centrifuge 22. The liquid product is sent into the liquid product collection device 21 through the liquid production pipe by the oil pump 4. The collected liquid product is separated into water and tar in the centrifuge 22. The oil pump is used to extract the liquid product obtained from coal seam pyrolysis to the surface. The gas production pipe 7 is used to transport the pyrolysis gas and purging gas remaining in the coal seam after hydrogen production to the surface.

[0044] Specifically, it also includes an air compressor 15, whose inlet is connected to air, and whose outlet is connected to the inlet of a first flow meter 16. The inlet of the first flow meter 16 is also connected to the outlet of a thermal inert gas, and the outlet of the first flow meter 16 is connected to the inlet of the injection well 9. The air compressor 15 is used to pressurize an appropriate amount of air and inject it into the underground coal seam 3 through the injection well to assist in the combustion and heating of organic matter in the coal seam 3. The first flow meter 16 is used to control the flow rate of the gas injected into the coal seam 3.

[0045] Specifically, the outlet of the hydrogen separation device 18 is connected to the first inlet of the gas separation device 19. The hydrogen separation device 18 is also used to separate hydrogen. The second inlet of the gas separation device 19 is connected to the outlet of the gas production pipe 7. The first outlet of the gas separation device 19 discharges CO2 for the preparation of supercritical CO2. The second outlet of the gas separation device 19 is connected to the inlet of the injection well 9, so that the separated purging gas is introduced into the injection well 9 for gas drive.

[0046] Specifically, the gas separation device 19 is used to separate the purge gas from the produced gas for recycling, and to separate CO2 to produce supercritical CO2; the liquid product collection device 21 is used to collect the produced liquid oil; the centrifuge 21 is used to separate pyrolysis water and tar from the oil.

[0047] Specifically, a combustion zone 8 is provided in the coal seam 3. The combustion zone 8 is generated by fracturing the coal seam. The combustion zone 8 is a place where coal or externally supplied fuel undergoes controlled and mild oxidative combustion under the action of igniter and combustion aid, and can provide heat for the pyrolysis of the coal seam 3.

[0048] Specifically, the top of coal seam 3 is the roof 1, and the bottom of coal seam 3 is the floor 2.

[0049] Specifically, the new energy power generation device 20 can use new energy sources such as solar energy and wind energy to generate electricity and supply energy; the heating medium 12 is high-temperature superheated steam or high-temperature molten salt, wherein the high-temperature molten salt can be potassium-based binary molten salt and sodium-based binary molten salt with good heat storage and thermal conductivity.

[0050] Example 2

[0051] An underground in-situ pyrolysis hydrogen production device for coal, such as Figure 3 and 4 As shown, the system includes an injection well 9, a production well 5, and a gas shift production well 10, all vertically arranged within the coal seam 2. The depths of the production well 5 and the injection well 9 are greater than those of the gas shift production well 10. The gas shift production well 10 is located between the production well 5 and the injection well 9. The gas shift production well 10 includes two vertical wells 101, whose bottoms are connected by a horizontal well 102. The horizontal well 102 contains a second methane steam reforming catalyst packing layer 24. The gas outlets of the two vertical wells 101 are connected to the gas inlet of a hydrogen separation device 18. The gas inlet of the injection well 9 is connected to the gas outlet of a supercritical fluid generator 27, which provides supercritical carbon dioxide and supercritical superheated steam.

[0052] Specifically, the outlet of the hydrogen separation device 18 is connected to the first inlet of the gas separation device 19. The hydrogen separation device 18 is also used to separate hydrogen. The second inlet of the gas separation device 19 is connected to the outlet of the gas production pipe 7. The first outlet of the gas separation device 19 discharges CO2 for the preparation of supercritical CO2. The second outlet of the gas separation device 19 is connected to the inlet of the injection well 9, so that the separated purging gas is introduced into the injection well 9 for gas drive.

[0053] Specifically, a screen pipe (11) is fitted on the outside of the horizontal well (102).

[0054] Specifically, when a second methane steam reforming catalyst packing layer 24 is installed inside the horizontal well 102, a CO2 adsorption material packing layer 23 is sleeved on the outside of the horizontal well 102. The CO2 adsorption material packing layer 23 is a thin container welded to the outside of the horizontal well 102 and is used to fill CO2 adsorption material. The thickness of the CO2 adsorption material packing layer 23 is 3 cm to 5 cm.

[0055] The adsorbent material may include one or more solid adsorbent materials such as CaO, MgO, Li2ZrO3, Li4SiO4, and activated carbon, which are used to efficiently adsorb and separate CO2.

[0056] Specifically, the first outlet of the gas separation device 19 is connected to the inlet of the supercritical fluid generator 27, the outlet of the supercritical fluid generator 27 is connected to the inlet of the injection well 9, and a second flow meter 28 can be installed between the outlet of the supercritical fluid generator 27 and the inlet of the injection well 9 for monitoring.

[0057] Specifically, the air inlet of the supercritical fluid generator 27 may not be connected to the first air outlet of the gas separation device 19. Instead, superheated steam is introduced into the air inlet of the supercritical fluid generator 27 to generate supercritical superheated steam.

[0058] Specifically, two supercritical fluid generators 27 can be set up to introduce superheated steam and carbon dioxide respectively, thereby generating supercritical superheated steam and supercritical carbon dioxide.

[0059] Specifically, the supercritical fluid generator 27 is used to produce supercritical superheated steam or supercritical carbon dioxide, which are used as the heating medium for coal seam pyrolysis and the raw material for pyrolysis upgrading. The supercritical superheated steam is in a state with a temperature greater than 374.15℃ and a pressure greater than 22.13MPa; the supercritical carbon dioxide is in a state with a temperature greater than 30.35℃ and a pressure greater than 7.375MPa. In actual production, the temperature of supercritical water is controlled at 600℃~650℃ and the pressure at 20MPa~30MPa; the temperature of supercritical carbon dioxide is controlled at 600℃~650℃ and the pressure at 8MPa. Pa ~ 12 MPa; Supercritical state (SC) is a state above the critical temperature and critical pressure but close to the critical point; Gases with both temperature and pressure above the critical point are called supercritical fluids. Supercritical fluids are excellent reaction media, capable of transforming heterogeneous reactions into homogeneous reactions and accelerating chemical reaction rates; When water reaches its critical pressure and critical temperature, water and steam have the same density, and the boundary between water and steam becomes indistinguishable. At this point, supercritical water vapor is not only an excellent reaction medium but can also react well with oil and gas; Supercritical carbon dioxide can undergo physicochemical reactions with organic groups and minerals in coal, altering the aromatic carbon network structure of coal, improving the pyrolysis reactivity of coal, and also enhancing the stability of alkali metal catalysts.

[0060] Example 3

[0061] A method for producing hydrogen from underground coal through in-situ pyrolysis, based on the underground coal through-situ pyrolysis hydrogen production apparatus in Example 1, includes the following steps:

[0062] According to the structure in Example 1, an injection well 9, a production well 5, and a gas conversion production well 10 are drilled. A proppant mixed with externally supplied fuel (or a portion of the coal burned directly without external fuel) and an igniter is injected into the coal seam 3 along with fracturing fluid, fracturing the coal seam to form fractures that fill the entire coal seam 3. The production well 5 is then closed, and hot inert gas is injected into the injection well 9 to preheat the coal seam 3, raising its temperature to 10°C-20°C above the ignition point of the igniter. Then, the air compressor 15 is turned on to inject air or oxygen-enriched gas into the coal seam 3, causing the igniter to spontaneously combust. The igniter releases a large amount of gas instantly upon combustion. The heat is measured to bring the locally supplied external fuel or coal to its ignition point and begin combustion, continuously releasing heat to heat coal seam 3 for pyrolysis. Due to gravity, the gaseous products produced by pyrolysis accumulate in the upper part of coal seam 3, and successively pass through the screen pipe 11 of the gas shift production well 10, the methanation catalyst filling layer 6, and the first methane steam reforming catalyst filling layer 14 to undergo methanation and methane steam reforming reactions. After being produced to the surface, hydrogen is separated by the hydrogen separation device 18. The remaining gas after dehydrogenation can be further separated and purified by the gas separation device 19. The concentration change of the produced hydrogen is monitored. When the hydrogen concentration is too low, it can be considered that the main stage of hydrogen production has ended. Afterwards, the gas conversion production well 10 is closed, the oil and gas production well 5 is opened, the air injection is stopped, and purging gas (generally N2, CO2, superheated steam, etc.) is injected into the injection well 9. The oil pump 4 is then turned on to extract the pyrolysis gas remaining in the coal seam 3 and the liquid phase products remaining at the bottom of the coal seam to the surface. The gas phase products are separated into purging gas by the gas separation device 19 for recycling, and the liquid phase products are separated into tar and pyrolysis water by the centrifuge 22.

[0063] Specifically, the externally supplied fuel is biochar, biomass, or high-density fuel, which can undergo controlled combustion and heat release in the underground coal seam, heating the coal seam and promoting pyrolysis. The igniter is red phosphorus or a flammable high-calorific-value substance with an ignition point between 100℃ and 300℃. The ignition point of the igniter is lower than that of the externally supplied fuel or the coal itself. If the preheating temperature is sufficient for the externally supplied fuel or coal to ignite spontaneously, an igniter may not be used. The combustion aid is air or oxygen-enriched gas, and the amount of gas injected is only enough to meet the oxygen requirements of the combustion process.

[0064] Specifically, during fracturing, a proppant containing a certain proportion of fuel and igniter is injected into the fracturing fracture along with the fracturing fluid, filling the entire fracturing zone. The mixing ratio of igniter and fuel by weight is generally between 1:100 and 1:5 to ensure ignition of the fuel. The ratio of externally supplied fuel to coal by weight is generally between 1:10 and 1:1. The actual ratio can be determined according to the specific properties of the local coal seam, ensuring that the externally supplied fuel can generate sufficient heat to assist in the pyrolysis of the coal seam. The proppant is quartz sand or artificial ceramsite.

[0065] Specifically, the methanation catalyst filling layer 6 is used to fill the methanation catalyst. The amount of catalyst filling should be determined according to the well layout and size of the gas shift production well and the actual capacity of the coal seam. The methanation catalyst mainly adopts a nickel-based catalyst, including an active component and a support. The active component is Ni, and the support is an Al2O3-ZrO2 composite oxide. The methanation catalyst can catalytically convert CO and CO2 in the pyrolysis gas into CH4 at a temperature of 350℃-450℃.

[0066] The second methane steam reforming catalyst filling layer 24 is used to fill the methane steam reforming catalyst. The filling amount of the methane steam reforming catalyst should be determined according to the well layout of the gas shift production well and the actual capacity of the coal seam. The methane steam reforming catalyst can be a highly active, sintering-resistant Ni-based catalyst, including an active component and a support. The active component is Ni, and the support is layered silicate. This catalyst can make the methane conversion rate close to 90% at 800℃, thereby significantly increasing the H2 content in the produced gas.

[0067] Specifically, the hydrogen production catalyst can be a single-metal or multi-metal transition metal catalyst such as Fe3O4, CeO2, TiO2, Ni / Co-ZrO2, NiO / TiO2 / ZnTiO3, or Ni / ash / γAl2O3. These catalysts can achieve hydrogen production from the reforming of organic compounds such as tar, phenol, naphthalene, and benzene at temperatures ranging from 450℃ to 900℃, with a conversion rate greater than 98% under optimal reaction conditions. The catalyst can be mixed with a proppant and injected into the fracturing fracture along with the fracturing fluid.

[0068] Example 4

[0069] A method for producing hydrogen from underground coal through in-situ pyrolysis, based on the underground coal through-situ pyrolysis hydrogen production apparatus in Example 2, includes the following steps:

[0070] According to the structure in Example 2, injection well 9, production well 5, and gas shift production well 10 are drilled. Proppant mixed with a hydrogen production catalyst is injected into coal seam 3 along with fracturing fluid, fracturing the coal seam to form fractures that fill the entire coal seam 3. First, production well 5 is closed, and supercritical fluid generator 27 is turned on to generate supercritical carbon dioxide (temperature 600℃~650℃, pressure 8MPa~12MPa) or supercritical water vapor (temperature 600℃~650℃, pressure 20MPa~30MPa). The injection volume ratio of supercritical water vapor and supercritical carbon dioxide is controlled to (2.0~2.5):1 by the second flow meter 28. The hot coal seam undergoes pyrolysis under the combined action of supercritical fluid and hydrogen production catalyst. Due to gravity, the gaseous products generated by pyrolysis accumulate in the upper part of the coal seam, passing through a CO2 adsorption material filling layer 23 to remove acidic CO2 gas from the pyrolysis gas. The pyrolysis gas then passes through a screen pipe 11 into a gas shift production well 10, where it undergoes methanation after passing through a second methane steam reforming catalyst filling layer 24. The extracted gas is then brought to the surface and separated into hydrogen gas by a hydrogen separation device 18. The remaining gas after dehydrogenation is further separated and purified by a gas separation device 19. The separated CO2 gas is sent to a supercritical fluid generator 27 for the production of supercritical CO2. The concentration of extracted hydrogen is monitored; when the hydrogen concentration is too low, the main stage of hydrogen production is considered to have ended. Afterwards, the gas conversion production well 10 is closed, the oil and gas production well 5 is opened, and purging gas (generally N2, CO2, superheated steam, etc.) is injected into the injection well 9. The oil pump 4 is then turned on to extract the pyrolysis gas remaining in the coal seam and the liquid phase products remaining at the bottom of the coal seam to the surface. The gas phase products are separated into purging gas by the gas separation device 19 for recycling, and the liquid phase products are separated into tar and pyrolysis water by the centrifuge 22.

[0071] After supercritical fluid is injected into coal seam 3, during the pyrolysis process that produces oil and gas products, it will undergo a series of reactions with tar and other substances under high temperature and pressure, including oxidative cracking, dehydrogenation, conversion, and methanation. Some of the possible reaction equations are as follows:

[0072] Hydrocarbon cracking reactions:

[0073] C n H m ------C n H 2n +CH3-CH3

[0074] C n H m ------CH4+CH3CH=CH2

[0075] C n H m +nH2O→nCO+(n+m / 2)H2

[0076] C n H m ------CH4+3H2

[0077] Phenol steam reforming reaction:

[0078] C6H5OH + 11H2O → 6CO2 + 14H2

[0079] C6H5OH + 5H2O → 6CO + 8H2

[0080] Naphthalene steam reforming reaction:

[0081] C 10 H8 + 20H2O → 10CO2 + 24H2

[0082] C 10 H8 + 10H2O → 10CO2 + 14H2

[0083] Methanation reaction

[0084] C + 2H₂ = CH₄

[0085] Methane steam reforming reaction:

[0086] CH4 + H2O = CO + 3H2 (1)

[0087] CO + H₂O = CO₂ + H₂ (2)

[0088] CH4 + 2H2O = CO2 + 4H2 (3)

[0089] CH4 + CO2 = 2CO + 2H2 (4)

[0090] CH4 + 3CO2 = 4CO + 2H2O (5)

[0091] CH4=C+2H2 (6)

[0092] 2CO=C+CO2 (7)

[0093] CO + H₂ = C + H₂O (8)

[0094] CO2 + 2H2 = C + 2H2O (9)

[0095] CH4 + 2CO = 3C + 2H2O (10)

[0096] CH4 + CO = 2C + 2H2O (11)

[0097] In actual production, since water vapor is always in excess, the carbon evolution reaction of reactions (6) to (11) can be avoided to the greatest extent. According to the experimental results, the reaction rates of reactions (4) and (5) are relatively slow and can be basically ignored in actual production. Reaction (3) is the result of the superposition of reactions (1) and (2). Therefore, reactions (1) and (2) play a dominant role in the methane water vapor reforming process.

[0098] Example 5

[0099] A method for producing hydrogen from underground coal through in-situ pyrolysis, based on the underground coal through-situ pyrolysis hydrogen production apparatus in Example 2, includes the following steps:

[0100] Drill injection well 9, production well 5, and gas shift production well 10 as required. A proppant mixed with a hydrogen production catalyst (the hydrogen production catalyst can be a single-metal or multi-metal transition metal catalyst such as Fe3O4, CeO2, TiO2, Ni / Co-ZrO2, NiO / TiO2 / ZnTiO3, Ni / ash / γAl2O3, etc.; the proppant can be quartz sand or artificial ceramsite) is injected into the coal seam along with the fracturing fluid. This fracturing creates fractures that fill the entire coal seam. First, close production well 5 and turn on supercritical fluid generator 27 to produce supercritical carbon dioxide (600℃~650℃, pressure 8MPa~12MPa) or supercritical water vapor (600℃~650℃, pressure 20MPa). The injection rate of supercritical steam or supercritical carbon dioxide is controlled by the first flow meter 16 (approximately 30 MPa). This heats the coal seam, causing it to undergo pyrolysis under the combined action of supercritical fluid and a hydrogen production catalyst. Due to gravity, the gaseous products generated by pyrolysis accumulate at the top of the coal seam. They then pass through a CO2 adsorption material layer to remove acidic CO2 gas from the pyrolysis gas. The pyrolysis gas then passes through a screen pipe 11 into a gas shift production well 10. A methane steam reforming hydrogen production reaction occurs in the dimethane steam reforming catalyst layer 24. The produced hydrogen is then extracted to the surface and separated by a hydrogen separation device 18 (a hydrogen selective permeable semi-permeable membrane component). The remaining gas after dehydrogenation is further separated and purified by a gas separation device 19. The separated CO2 gas is sent to a supercritical fluid generator 27 for supercritical CO2 production. The concentration of the extracted hydrogen is monitored; when the hydrogen concentration is too low, the main hydrogen production stage is considered complete. Afterwards, the gas conversion production well 10 is closed, the production well 5 is opened, and purging gas (generally N2, CO2, superheated steam, etc.) is injected into the injection well 9. The oil pump 4 is then turned on to extract the pyrolysis gas remaining in the coal seam and the liquid phase products remaining at the bottom of the coal seam to the surface. The gas phase products are separated into purging gas by the gas separation device 19 for recycling, and the liquid phase products are separated into tar and pyrolysis water by the centrifuge 22.

[0101] Example 6

[0102] A method for producing hydrogen through underground in-situ pyrolysis of coal, such as Figure 5 and 6 As shown, it includes the following steps:

[0103] After the main pyrolysis hydrogen and oil / gas production stage is completed, coal seam 3 is left to stand for several days to allow its temperature to drop to room temperature. Then, a certain amount of sulfate-reducing bacteria (Klebsiella aerogenes) is introduced into the pyrolyzed coal seam to fill the entire fracture. The well is then shut in for several days (generally more than 7 days) to allow the sulfate-reducing bacteria to fully contact the residual tar and other organic matter between the fractures and to undergo an anaerobic hydrogen production reaction. After the reaction is complete, injection well 9 and production well 5 are opened, and purging gas (generally N2, CO2, superheated steam, etc.) is injected into the coal seam. The generated hydrogen is brought to the surface for separation and purification, and the purging gas is recycled.

[0104] Specifically, sulfate-reducing bacteria are used after the main stage of underground coal seam pyrolysis oil and gas production is completed. They are placed in the underground coal seam to anaerobic decompose the organic matter such as tar remaining in the coal seam fractures to produce hydrogen, thereby further increasing the hydrogen production.

[0105] Sulfate-reducing bacteria are a major type of environmental anaerobic bacteria with high levels of hydrogenase. Hydrogenase is an enzyme responsible for producing H2 and usually exists in multiple copies in the genome, so sulfate-reducing bacteria have a high potential for hydrogen production. The strain of sulfate-reducing bacteria that can be selected is Klebsiella aerogenes, which is a short rod-shaped bacterium. The suitable pH range for growth is 7.0 to 7.6, with the optimum pH being 7.0. The suitable temperature range for growth is 15 to 40°C, with the optimal growth temperature being 37°C.

[0106] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A coal underground in-situ pyrolysis hydrogen production device, characterized in that, It includes an injection well (9), a production well (5), and a gas shift production well (10) vertically set in the coal seam (2). The depth of the production well (5) and the injection well (9) is greater than that of the gas shift production well (10). The gas shift production well (10) is set between the production well (5) and the injection well (9). The gas shift production well (10) includes two vertical wells (101). The bottoms of the two vertical wells (101) are connected by a horizontal well (102). The horizontal well (102) is provided with a methanation catalyst filling layer (6). The middle of the two vertical wells (101) is provided with a first methane steam reforming catalyst filling layer (14). The gas outlets of the two vertical wells (101) are connected to the gas inlet of the hydrogen separation device (18).

2. The underground in-situ pyrolysis hydrogen production device according to claim 1, characterized in that, Each vertical shaft (101) has a first insulation cotton layer (13) on its outer side wall. The first insulation cotton layer (13) and the vertical shaft (101) form a first space, which is filled with a heating medium (12).

3. The underground in-situ pyrolysis hydrogen production device according to claim 1, characterized in that, The injection well (9) has a resistance wire layer (25) and a second insulation cotton layer (26) arranged sequentially from the inside to the outside on the outer side of the inlet.

4. The underground in-situ pyrolysis hydrogen production device according to claim 1, characterized in that, The well (5) is equipped with a gas extraction pipe (7) and a liquid extraction pipe. The bottom of the liquid extraction pipe is equipped with an oil pump (4). The outlet of the liquid extraction pipe is connected to the inlet of the liquid product collection device (21). The outlet of the liquid product collection device (21) is connected to the inlet of the centrifuge (22).

5. A coal underground in-situ pyrolysis hydrogen production device according to claim 1, characterized in that, It also includes an air compressor (15), the air compressor (15) has an air inlet that is connected to air, the air compressor (15) has an air outlet that is connected to the air inlet of a first flow meter (16), and the air outlet of the first flow meter (16) is connected to the inlet of an injection well (9).

6. The underground in-situ pyrolysis hydrogen production device for coal according to claim 1, characterized in that, The outlet of the hydrogen separation device (18) is connected to the first inlet of the gas separation device (19). The hydrogen separation device (18) is used to separate hydrogen from the pyrolysis gas discharged from the vertical well (101). The second inlet of the gas separation device (19) is connected to the outlet of the gas extraction pipe (7). The first outlet of the gas separation device (19) is connected to the inlet of the supercritical fluid generator (27). The outlet of the supercritical fluid generator (27) is connected to the inlet of the injection well (9). The second outlet of the gas separation device (19) is connected to the inlet of the injection well (9).

7. A coal underground in-situ pyrolysis hydrogen production device, characterized in that, The system includes an injection well (9), a production well (5), and a gas shift production well (10) vertically disposed within the coal seam (2). The depths of the production well (5) and the injection well (9) are greater than those of the gas shift production well (10). The gas shift production well (10) is disposed between the production well (5) and the injection well (9). The gas shift production well (10) includes two vertical wells (101). The bottoms of the two vertical wells (101) are connected by a horizontal well (102). The horizontal well (102) is provided with a second methane steam reforming catalyst packing layer (24). The outlets of the two vertical wells (101) are connected to the inlet of a hydrogen separation device (18). The inlet of the injection well (9) is connected to the outlet of a supercritical fluid generator (27). The supercritical fluid generator (27) is used to provide supercritical carbon dioxide and supercritical superheated steam.

8. A coal underground in-situ pyrolysis hydrogen production device according to claim 7, characterized in that, The horizontal well (102) is fitted with a CO2 adsorption material filling layer (23) on its outer side.

9. A method for producing hydrogen from coal through underground in-situ pyrolysis, based on the coal underground in-situ pyrolysis hydrogen production apparatus according to any one of claims 1 to 6, characterized in that, Includes the following steps: An injection well (9), a production well (5), and a gas shift production well (10) are opened in the coal seam (3). Fuel, igniter, proppant, and fracturing fluid are injected into the coal seam (3). The production well (5) is closed. Thermal inert gas is injected into the injection well (9) to preheat the coal seam (3) so that the igniter can burn. Air or oxygen-enriched gas is introduced into the injection well (9) so that the igniter and fuel can continuously release heat to heat the coal seam (3) for pyrolysis. The gaseous products generated by pyrolysis enter the gas shift production well (10). The gaseous products undergo methanation reaction and methane steam reforming reaction in sequence with the methanation catalyst filling layer (6) and the first methane steam reforming catalyst filling layer (14). After that, they are extracted to the surface and separated by a hydrogen separation device (18) to obtain hydrogen. After the hydrogen preparation is completed, the production well (5) is opened, the air injection is stopped, and purging gas is injected into the injection well (9) to extract the pyrolysis gas remaining in the coal seam (3) and the liquid products remaining at the bottom of the coal seam to the surface.

10. A method for producing hydrogen from coal through underground in-situ pyrolysis, based on the coal underground in-situ pyrolysis hydrogen production apparatus according to any one of claims 7-8, characterized in that, Includes the following steps: An injection well (9), a production well (5), and a gas shift production well (10) are opened in the coal seam (3). The hydrogen production catalyst and proppant are injected into the coal seam (3) along with the fracturing fluid. The coal seam is fracturing to form fractures. The production well (5) is closed. Supercritical carbon dioxide or supercritical superheated steam is injected into the injection well (9) through a supercritical fluid generator (27). The coal in the coal seam undergoes a pyrolysis reaction under the dual action of supercritical carbon dioxide or supercritical superheated steam and the hydrogen production catalyst. The gaseous products generated by pyrolysis accumulate in the upper part of the coal seam. After passing through the second methane steam reforming catalyst filling layer (24), a methane steam reforming reaction occurs. The product is then extracted to the surface and separated by a hydrogen separation device (18) to obtain hydrogen. After the hydrogen preparation is completed, the production well (5) is opened, the air injection is stopped, and purging gas is injected into the injection well (9). The pyrolysis gas remaining in the coal seam (3) and the liquid products remaining at the bottom of the coal seam are extracted to the surface.

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