High pressure oxidation apparatus for low concentration gas

Abstract

The application relates to a high-pressure oxidation device for low-concentration gas, which comprises a centrifugal compressor, a high-pressure conveying pipeline and a high-pressure oxidation furnace. The centrifugal compressor is connected with the gas inlet end of the high-pressure conveying pipeline and is suitable for conveying the pressurized gas into the high-pressure conveying pipeline. The high-pressure oxidation furnace comprises a furnace shell, a heat storage device and an ignition device. The furnace shell is provided with a gas inlet suitable for entering the gas and a gas outlet suitable for outputting high-temperature flue gas. The gas outlet end of the high-pressure conveying pipeline is connected with the gas inlet and is suitable for conveying the gas into the furnace shell. The gas outlet is suitable for being connected with the high-temperature flue gas inlet end of a turbine generator. The heat storage device is arranged in the cavity of the furnace shell and the two ends of the heat storage device are respectively opposite to the gas inlet and the gas outlet. The gas entering from the gas inlet flows through the heat storage device and enters the cavity of the furnace shell to be high-temperature oxidized. The ignition device is arranged on the side wall of the furnace shell and the ignition end of the ignition device is located in the cavity of the furnace shell.

Description

Technical Field

[0001] This application relates to the field of low-concentration gas utilization technology, and in particular to a high-pressure oxidation device for low-concentration gas. Background Technology

[0002] In modern coal mining, many coal seams contain associated coalbed methane. During mining, this methane needs to be extracted beforehand or during the excavation process. Due to blockages and air leakage, air mixes with the methane, forming a mixture known as coal mine gas. Mine exhaust gas (also called waste gas) with a methane concentration below 0.75% is characterized by high flow rate and low concentration. Direct emission would severely pollute the air. Therefore, researching technologies for utilizing low-concentration coal mine gas is of great significance for improving gas utilization efficiency, reducing coal mine gas emissions, and minimizing atmospheric pollution. Summary of the Invention

[0003] In view of this, this application proposes a high-pressure oxidation device for low-concentration methane gas, which is suitable for assisting in the utilization of low-concentration methane.

[0004] According to one aspect of this application, a high-pressure oxidation device for low-concentration methane gas is provided, comprising: a centrifugal compressor, a high-pressure conveying pipeline, and a high-pressure oxidation furnace;

[0005] The centrifugal compressor is connected to the inlet end of the high-pressure transmission pipeline and is suitable for pressurizing gas and then transmitting it into the high-pressure transmission pipeline.

[0006] The high-pressure oxidation furnace includes: a furnace shell, a heat storage device, and an ignition device; the furnace shell has an inlet for gas to enter and an outlet for high-temperature flue gas to exit; the outlet end of the high-pressure conveying pipeline is connected to the inlet for conveying gas into the furnace shell; the outlet is suitable for connecting to the high-temperature flue gas inlet end of the turbine generator.

[0007] The heat storage device is installed inside the cavity of the furnace shell, and the two ends of the heat storage device are respectively opposite to the air inlet and the air outlet, so that the gas entering from the air inlet flows through the heat storage device and enters the cavity of the furnace shell for high-temperature oxidation.

[0008] The ignition device is located on the side wall of the furnace shell, and the ignition end of the ignition device is located inside the cavity of the furnace shell.

[0009] In one possible implementation, a shut-off valve is installed on the high-pressure transmission pipeline.

[0010] In one possible implementation, a dry flame arrester is installed on the high-pressure transmission pipeline, and the shut-off valve and the dry flame arrester are arranged sequentially along the flow direction of the gas in the high-pressure transmission pipeline.

[0011] In one possible implementation, the heat storage device includes: a front guide fluid, a heat storage body, and a rear guide fluid connected in sequence;

[0012] The end of the front guide fluid that is furthest from the heat storage body is opposite to the air inlet, and the end of the rear guide fluid that is furthest from the heat storage body is opposite to the air outlet.

[0013] In one possible implementation, the heat storage body is a tubular structure made of rolled metal wire mesh.

[0014] In one possible implementation, both the main bodies of the leading fluid and the trailing fluid are frustum-shaped, and the larger diameter ends of both the leading fluid and the trailing fluid are close to the heat storage body.

[0015] In one possible implementation, there are two or more high-pressure conveying pipelines and two or more heat storage devices inside the furnace shell; the number of high-pressure conveying pipelines is the same as the number of heat storage devices and they are connected in a one-to-one correspondence.

[0016] In one possible implementation, it further includes: a main gas pipeline, the inlet ends of two or more of the high-pressure delivery pipelines being connected to the main gas pipeline, a centrifugal compressor being installed at the beginning of the main gas pipeline, and the gas being suitable for entering each high-pressure delivery pipeline through the main gas pipeline.

[0017] In one possible implementation, a flow regulating valve is installed on the main gas pipeline.

[0018] Beneficial effects: The centrifugal compressor is connected to the inlet of the high-pressure delivery pipeline, suitable for pressurizing the gas to provide the power to drive the turbine blades of the turbine generator. The high-pressure delivery pipeline is suitable for transporting the gas to the interior of the high-pressure oxidizer. The high-pressure oxidizer is suitable for burning and oxidizing the gas. The oxidized flue gas enters the turbine generator from the outlet of the furnace shell. The turbine generator generates electricity by converting the kinetic energy of the flue gas into mechanical rotational kinetic energy, and then into electrical energy. The two ends of the heat storage device are connected to the inlet and outlet of the furnace shell, respectively, so that the gas entering from the inlet flows through the heat storage device and enters the cavity of the furnace shell for high-temperature oxidation. After oxidation, it flows out from the heat storage device to the outlet. The role of the heat storage device here is to increase the heat and mass transfer process at high temperature and activate the reaction chain through collision with the vessel wall, so that all unburned gas can be burned completely. This application develops a new process for coal mine gas power generation, which effectively utilizes the flue gas formed by the combustion and oxidation of low-concentration gas after pressurization, thus avoiding energy waste and environmental pollution caused by the direct discharge of low-concentration gas to the outside.

[0019] Other features and aspects of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0020] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this application together with the specification and serve to explain the principles of this application.

[0021] Figure 1 This diagram shows the structural connection of a high-pressure oxidation device for low-concentration methane gas according to an embodiment of this application.

[0022] Figure 2 A cross-sectional view of a high-pressure oxidation furnace according to an embodiment of this application is shown;

[0023] Figure 3 Show Figure 2 A magnified view of a portion of the image;

[0024] Figure 4 A longitudinal sectional view of a high-pressure oxidation furnace according to an embodiment of this application is shown;

[0025] Figure 5 A side view of a high-pressure oxidation furnace according to an embodiment of this application is shown.

[0026] Centrifugal compressor 800, high-pressure conveying pipeline 200, dry flame arrester 220, high-pressure preheater 230, high-pressure oxidation furnace 300, ignition device 400, air inlet 421, air outlet 452, gas distributor 240, front guide fluid 710, heat storage body 700, rear guide fluid 720, inner cylinder 730, inner lining insulation layer 900, front end cover 420, furnace wall 410, rear end cover 450, main water inlet pipe 500, branch water inlet pipe 510, main water outlet pipe 600, branch water outlet pipe 610, outer support ring 740, inner support ring 750, outer support block 741. Detailed Implementation

[0027] Various exemplary embodiments, features, and aspects of this application will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0028] It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application or to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0030] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0031] Furthermore, to better illustrate this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented without certain specific details. In some instances, methods, means, components, and circuits well-known to those skilled in the art have not been described in detail in order to highlight the main points of this application.

[0032] Figure 1 This diagram shows the structural connection of a high-pressure oxidation device for low-concentration methane gas according to an embodiment of this application. Figure 2 A cross-sectional view of a high-pressure oxidation furnace according to an embodiment of this application is shown; Figure 3 Show Figure 2 A magnified view of a portion of the image; Figure 4 A longitudinal sectional view of a high-pressure oxidation furnace according to an embodiment of this application is shown; Figure 5 A side view of a high-pressure oxidation furnace according to an embodiment of this application is shown. Figure 1 As shown, a high-pressure oxidation device for low-concentration methane gas includes: a centrifugal compressor 800, a high-pressure conveying pipeline 200, and a high-pressure oxidizing furnace 300; the centrifugal compressor 800 is connected to the inlet end of the high-pressure conveying pipeline 200, suitable for pressurizing the methane gas and conveying it into the high-pressure conveying pipeline 200; the high-pressure oxidizing furnace 300 includes: a furnace shell, a heat storage device, and an ignition device 400; the furnace shell has an inlet 421 for entering the methane gas and an outlet 452 for outputting high-temperature flue gas; the high-pressure conveying... The outlet of pipe 200 is connected to the inlet 421 for conveying gas into the furnace shell; the outlet 452 is connected to the high-temperature flue gas inlet of the turbine generator; the heat storage device is installed inside the furnace shell cavity and its two ends are connected to the inlet 421 and the outlet 452 respectively, so that the gas entering from the inlet 421 flows through the heat storage device and enters the furnace shell cavity for high-temperature oxidation; the ignition device 400 is installed on the side wall of the furnace shell and the ignition end of the ignition device 400 is located inside the furnace shell cavity.

[0033] It should be noted here that the centrifugal compressor 800 is connected to the inlet end of the high-pressure conveying pipeline 200, which is suitable for pressurizing the gas to give it the power to drive the turbine blades of the turbine generator to rotate; the high-pressure conveying pipeline 200 is suitable for conveying the gas to the inside of the furnace shell of the high-pressure oxidizer 300, which is suitable for combustion and oxidation of the gas. The oxidized flue gas enters the turbine generator from the outlet 452 of the furnace shell. When the flue gas is injected into the turbine in the turbine generator, the kinetic energy of the flue gas is converted into the kinetic energy of the turbine blades. The turbine blades start to rotate after being impacted by the flue gas. The rotational motion is transmitted to the generator through the bearings and shaft. The magnetic field interaction between the rotor and stator in the generator generates electrical energy. The ignition device 400 uses atmospheric pressure gas for open flame ignition and gradual heating during the initial operation of the equipment without increasing the pressure. The two ends of the heat storage device are connected to the furnace shell's inlet 421 and outlet 452, respectively, so that the gas entering from the inlet 421 flows through the heat storage device and into the furnace shell cavity for high-temperature oxidation. After oxidation, it flows out from the heat storage device to the outlet 452. The function of the heat storage device here is to increase the heat and mass transfer process at high temperatures and activate the reaction chain through collision with the vessel wall, ensuring that all unburned gas is completely burned. This application develops a new coal mine gas power generation process, which pressurizes and oxidizes low-concentration gas, then sends the resulting flue gas to a turbine generator for utilization, avoiding energy waste caused by directly discharging low-concentration gas to the outside.

[0034] In one possible implementation, a shut-off valve 210 is provided on the high-pressure transmission pipeline 200. The shut-off valve 210 is suitable for controlling the flow of gas within the high-pressure transmission pipeline 200. When a fault or fire occurs at the downstream end, the shut-off valve 210 can be shut off in time to prevent the continued transmission of gas.

[0035] Furthermore, there are two shut-off valves 210, which are arranged adjacent to each other in sequence along the gas flow direction in the high-pressure conveying pipeline 200.

[0036] In one possible implementation, a dry-type flame arrester 220 is installed on the high-pressure conveying pipeline 200, and the shut-off valve 210 and the dry-type flame arrester 220 are arranged sequentially along the gas flow direction within the high-pressure conveying pipeline 200. It should be noted that the dry-type flame arrester 220 is a safety device to prevent the spread of flammable gas flames. If a deflagration occurs in the high-pressure oxidizer 300, it can prevent flame backflow into the high-pressure conveying pipeline 200, suppress the spread of flames within the pipeline, and improve the overall safety performance of the equipment while effectively utilizing low-concentration methane gas. The dry-type flame arrester 220 is configured with a pressure-bearing capacity of 4.0 MPa and is installed before the high-pressure preheater 230 in an area with a temperature below 500°C.

[0037] In one possible implementation, a high-pressure preheater 230 is also included; one end of the high-pressure conveying pipeline 200 is connected to the inlet of the high-pressure preheater 230, and the outlet of the high-pressure preheater 230 is connected to the inlet 421 of the high-pressure oxidizer 300. It should be noted that whether the high-pressure preheater 230 needs to be installed can be determined based on the actual design conditions. If the methane concentration of the gas is below 3%, the high-pressure preheater 230 must be installed; when the methane concentration of the gas is controlled very close to 5% (lower explosive limit), the high-pressure preheater 230 can be omitted. The high-pressure preheater 230 can further increase the initial temperature of the gas entering the high-pressure oxidizer 300 to achieve self-heating balance in the high-pressure oxidizer 300.

[0038] Furthermore, the high-pressure preheater 230 includes a heat exchange tube and a high-temperature resistant shell arranged coaxially; the heat exchange tube is disposed inside the cavity of the high-temperature resistant shell; one end of the high-pressure conveying pipe 200 is connected to one end (air inlet) of the heat exchange tube, and the other end (air outlet) of the heat exchange tube is connected to the air inlet 421 of the high-pressure oxidizer 300; the gas enters the high-pressure oxidizer 300 through the heat exchange tube in the high-pressure preheater 230, and the high-temperature resistant shell is provided with a medium inlet 232 suitable for entering the flue gas and a medium outlet 231 suitable for exiting the flue gas to introduce the flue gas, and the flue gas enters the high-temperature resistant shell and exchanges heat with the gas in the heat exchange tube to raise the temperature of the gas.

[0039] It should be noted that, considering the relatively high operating pressure (generally designed to be greater than 2.0 MPa) that the heat exchange tubes bear, and also taking into account the thermal expansion and contraction caused by temperature changes between high-temperature preheating environments and room temperature, as well as during the preheating process, spiral groove heat exchange tubes are preferred. Furthermore, to prevent premature oxidation of the methane gas during preheating, which could affect the equipment's temperature resistance, the heat exchange tubes are made of high-temperature resistant materials. Preferably, the material grade is 310S or higher, or alloy steel with a temperature resistance of over 1200℃, fully considering the temperature rise caused by premature oxidation of ultra-low concentration methane gas during preheating. The inner diameter of the heat exchange tubes is no greater than 12 mm, controlling it below the detonation critical diameter (12 mm) to prevent premature methane oxidation from accelerating flame propagation and causing detonation.

[0040] When a high-pressure preheater 230 is installed, the medium inlet 232 is suitable for connection to the exhaust port of the turbine generator, using back pressure to overcome resistance and thus introducing the flue gas from the turbine generator outlet into the high-pressure preheater 230. Alternatively, the medium inlet 232 can be directly connected to the exhaust port 452 of the high-pressure oxidizer 300 through a pipeline, thus directly circulating a portion of the flue gas output from the high-pressure oxidizer 300 into the high-pressure preheater 230. The high-pressure preheater 230 can use the high-temperature flue gas after oxidation to preheat the compressed gas and can be used to control the oxidation temperature of the high-pressure oxidizer 300; ensuring that the temperature of the flue gas formed after the gas oxidation is below 1100℃ (auto-ignition temperature) and above 900℃. When the oxidation temperature increases, the preheating temperature can be appropriately reduced; when the oxidation temperature decreases, the preheating temperature can be appropriately increased, always maintaining a relatively constant oxidation temperature. The preheating temperature is also related to the methane concentration in the gas. When the methane volume concentration in the gas is too low and the oxidation temperature of 900℃ cannot be maintained, it is necessary to increase the heat exchange of the preheating and raise the initial temperature to ensure the ambient temperature for oxidation. When the methane concentration in the gas can meet the oxidation temperature requirements, the heat exchange load of the preheating can be reduced, or even the heat exchange function of the preheater can be stopped.

[0041] In one possible implementation, a gas distributor 240 is also included. The gas distributor 240 is positioned between the high-pressure conveying pipeline 200 and the high-pressure oxidizer 300. The inlet of the gas distributor 240 is connected to the outlet of the high-pressure conveying pipeline 200, and the outlet of the gas distributor 240 is connected to the inlet 421 of the furnace shell. The gas distributor 240 improves the uniformity of gas entering the high-pressure oxidizer 300. It should also be noted that the gas distributor 240 can be omitted when the methane concentration is low.

[0042] In one possible implementation, an expansion joint is provided between the gas distributor 240 and the high-pressure delivery pipeline 200. Since the microchannels of the gas distributor 240 may become blocked, an expansion joint clamp that is easy to disassemble is provided for easy disassembly and maintenance.

[0043] It should be noted that when both the gas distributor 240 and the high-pressure preheater 230 are configured, the gas distributor 240 is located at the rear end of the high-pressure preheater 230, that is, between the gas outlet of the high-pressure conveying pipeline 200 and the gas inlet 421 of the furnace shell, the high-pressure preheater 230 and the gas distributor 240 are arranged in sequence.

[0044] In one possible implementation, such as Figure 2As shown, the heat storage device includes: a front guide fluid 710, a heat storage body 700 and a rear guide fluid 720 arranged sequentially along the length of the furnace shell; the end of the front guide fluid 710 away from the heat storage body 700 is opposite to the air inlet 421, and the end of the rear guide fluid 720 away from the heat storage body 700 is opposite to the air outlet 452. It should be noted that the guide fluid 710 is used to promptly deliver the gas entering the inlet 421 into the regenerator 700. Since the regenerator 700 is not a sealed structure, it has openings and gaps on its side walls. Therefore, after the gas enters the regenerator 700, it will overflow from the side walls of the regenerator 700 and flow into the cavity of the furnace shell. The gas will be burned and oxidized inside the cavity of the furnace shell. After oxidation, it will flow back into the regenerator 700 and finally into the guide fluid 720 and out from the outlet 452. During the process of the gas entering and leaving the high-pressure oxidizer 300, it will continuously collide with the regenerator 700 to improve the oxidation efficiency. At the same time, the regenerator 700 can appropriately reduce the flow rate of the gas and increase the residence time of the gas in the furnace shell, so that all unburned gas can be burned completely inside the furnace shell, ensuring that the gas is fully burned and oxidized.

[0045] In one embodiment, the heat storage body 700 is a tubular structure made of rolled metal wire mesh. It should be noted that the inner diameter of the gaps in the metal wire mesh is less than 2 mm, and it is rolled into a multi-layered interlaced structure. This allows the oxidizing reactants inside the furnace shell to undergo multiple collisions as they pass through the wire mesh layers, while also filtering the gas and preventing detached refractory material from being carried to the gas outlet 452.

[0046] In one energy storage method, the thickness of the heat storage body 700 ranges from 100 to 300 mm. It should be noted that the specific number of layers and thickness of the heat storage body 700 are determined based on the fluctuation range of the gas concentration. Generally, when the gas concentration is low and frequently falls below the lean-burn limit, the number of layers and thickness of the heat storage body 700 can be reduced. The optimal material for the heat storage body 700 is 27L7Mo2, with a temperature resistance rating of 1400℃.

[0047] In one energy realization method, an inner cylinder 730 is provided inside the heat storage body 700. The inner cylinder 730 is coaxially arranged with the heat storage body 700 to support the heat storage body 700, prevent deformation and breakage of the heat storage body 700, and prevent impurities from entering the subsequent turbine generator and damaging subsequent equipment. The main body of the inner cylinder 730 has a porous cylindrical structure, and gas enters and exits the inner cylinder 730 through multiple holes on the inner cylinder 730. The inner cylinder 730 is made of alloy steel of 310S or higher. The diameter of the perforations on the inner cylinder 730 is less than or equal to 1 mm.

[0048] In one possible implementation, both the front guide fluid 710 and the rear guide fluid 720 have a hollow frustum structure, and both circular ends of the front guide fluid 710 and the rear guide fluid 720 are open. Multiple perforations are provided on the sidewalls of both the front guide fluid 710 and the rear guide fluid 720 to allow gas to enter and exit through these perforations. Furthermore, the larger diameter end of both the front guide fluid 710 and the rear guide fluid 720 contacts the heat storage body 700.

[0049] Furthermore, such as Figure 2 As shown, the front guide fluid 710 and the rear guide fluid 720 are fixed to both ends of the inner cylinder 730 inside the heat storage body 700, respectively. Preferably, the front guide fluid 710 and the rear guide fluid 720 are fixed to both ends of the inner cylinder 730 by welding. The front guide fluid 710 is placed in the channel of the inner lining insulation layer 900 inside the front end cover 420; the rear guide fluid 720 is embedded in the channel of the inner lining insulation layer 900 inside the rear end cover 450; and there are reserved gaps between the front guide fluid 710, the rear guide fluid 720 and the inner wall of the channel to avoid stress caused by expansion.

[0050] In one possible implementation, the end of the inner cylinder 730 connected to the front guide fluid 710 is configured as a closed structure, so that the gas first contacts the heat storage body 700 through the front guide fluid 710. After the gas is oxidized on the outside of the inner cylinder 730, it continues to enter the inner wall of the inner cylinder 730 through the heat storage body 700, and enters the rear guide fluid 720 through the inner channel of the inner cylinder 730, and is finally released from the gas outlet 452.

[0051] The lengths of the guide fluid 710 and the guide fluid 720 are designed according to normal streamline proportions, with the principle of minimizing the resistance caused by the change in diameter. Preferably, the optimal ratio of the length of the guide fluid 710, the length of the heat storage body 700, and the length of the guide fluid 720 is 1:10:1.5.

[0052] In one possible implementation, there are two or more high-pressure conveying pipelines 200, and two or more heat storage devices are installed inside the furnace shell; the number of high-pressure conveying pipelines 200 is the same as the number of heat storage devices, and they are connected one-to-one. It should be noted that, in order to improve the oxidation efficiency of the gas, multiple heat storage devices are installed inside the furnace shell, and the multiple high-pressure conveying pipelines 200 are suitable for conveying gas to multiple heat storage devices respectively. The pressure resistance rating of the high-pressure conveying pipelines 200 is 4.0 MPa.

[0053] In one possible implementation, each high-pressure transmission pipeline 200 is further equipped with a regulating valve for adjusting the flow rate of methane gas within the pipeline 200, a flow meter for detecting the flow rate of methane gas within the pipeline 200, a concentration meter for detecting the methane concentration within the pipeline 200, and a thermometer for detecting the temperature of methane gas within the pipeline 200. The regulating valve, flow meter, concentration meter, and thermometer are arranged sequentially along the flow direction of the methane gas within the high-pressure transmission pipeline. The concentration meter and thermometer need to be observed simultaneously, and the control principle is to keep the methane concentration below the explosion limit at the corresponding temperature to prevent backfire or explosion in the pipeline due to static electricity, sparks, or other reasons during the high-pressure transmission process. The regulating valve is used to adjust the pressure and combustion load of the high-pressure transmission pipeline 200, and its adjustment principle is to ensure that the flow rate of methane gas in all high-pressure transmission pipelines 200 is as similar as possible.

[0054] Furthermore, the main body of the furnace shell is cylindrical with a hollow interior, and the shell can withstand pressures exceeding 4 MPa. Each heat storage device has the same structure, such as... Figure 3 As shown, each heat storage device is arranged in a ring along the circumference of the furnace shell.

[0055] In one possible implementation, the furnace shell includes: a front cover 420, a furnace wall 410, and a rear cover 450 fixedly connected; the main body of the furnace wall 410 is cylindrical and has a cavity with openings at both ends; the front cover 420 and the rear cover 450 are respectively fastened to the opposite ends of the furnace wall 410 to cover the openings at both ends of the furnace wall 410; the front cover 420 has two or more air inlets 421 and the rear cover 450 has two or more air outlets 452; the front guide fluid 710 and the rear guide fluid 720 of each heat storage device each correspond to one air inlet 421 and one air outlet 452, and the length direction of each heat storage device is parallel to each other.

[0056] Furthermore, the front cover 420 has six air inlets 421, which are arranged sequentially around the circumference of the front cover 420; the rear cover 450 has six air outlets 452, which are arranged sequentially around the circumference of the rear cover 450; a total of six heat storage devices are provided; the six air inlets 421, the six heat storage devices, and the six air outlets 452 are arranged in a one-to-one correspondence. The outer edge of the rear cover 450 is provided with a connecting flange 451, which is suitable for connection with a turbine generator.

[0057] In one possible implementation, the furnace wall 410 is a membrane water-cooled wall with multiple water flow channels inside, suitable for cooling the furnace wall 410 by removing heat through cooling water. The furnace wall 410 can withstand high-pressure water of 6.0 MPa. This ensures equipment safety, prevents the furnace wall 410 from deforming due to heat, and avoids reducing the pressure resistance of the furnace wall 410 due to high temperature. The furnace shell material is pressure vessel steel (generally 16MnR is best).

[0058] Furthermore, it also includes: a main water inlet pipe 500 and multiple branch water inlet pipes 510, the water inlet ends of the multiple branch water inlet pipes 510 being connected to the main water inlet pipe 500, and the water outlet ends of the multiple branch water inlet pipes 510 being connected to multiple water flow channels of the furnace wall 410 respectively, and the cooling water in the main water inlet pipe 500 flowing into the interior of the furnace wall 410 in sequence through the multiple branch water inlet pipes 510.

[0059] Furthermore, it also includes: a main water outlet pipe 600 and multiple branch water outlet pipes 610, the outlet ends of the multiple branch water outlet pipes 610 are connected to the main water outlet pipe 600, and the inlet ends of the multiple branch water outlet pipes 610 are respectively connected to multiple water flow channels of the furnace wall 410. Each cooling water inside the furnace wall 410 enters the main water outlet pipe 600 through the branch water outlet pipes 610 and is then discharged.

[0060] In one possible implementation, the inner wall of the furnace shell is fitted with an inner insulating lining 900, such as... Figure 2 As shown, the inner side of the furnace wall 410, the inner side of the front cover 420, and the inner side of the rear cover 450 are all provided with an inner heat insulation layer 900, which is suitable for preventing the cooling water in the furnace wall 410 from affecting the oxidation temperature inside the furnace shell and preventing the collision and destruction reaction chain of the cooler wall.

[0061] Furthermore, the inner insulation layer 900 is made of corundum mullite. The surface of corundum mullite is smooth, without burrs or peeling, which provides insulation and keeps the temperature of the oxidizing environment (internal environment of the furnace shell) of ultra-low concentration gas below 1100℃, while the temperature of the inner wall of the furnace shell reaches above 900℃.

[0062] The thickness of the inner lining insulation layer 900 on the inner side of the furnace wall 410 shall not be less than 150mm, and the optimal value shall be 300mm. If the insulation level does not meet the calculation requirements, a zirconium-containing aluminum silicate insulation layer can be added between the furnace wall 410 and the inner lining insulation layer 900 to further improve the insulation level.

[0063] The thickness of the inner lining insulation layer 900 on the inner side of the front cover 420 is not less than 150mm. Furthermore, a heat insulation layer 422 is provided between the inner side of the front cover 420 and the inner lining insulation layer 900. The heat insulation layer 422 is made of zirconium-containing aluminum silicate and has a thickness of not less than 300mm to ensure the heat insulation effect of the front cover 420.

[0064] The thickness of the inner lining insulation layer 900 inside the rear end cover 450 ranges from 200 to 300 mm. Furthermore, there is no need to set a zirconium-containing aluminum silicate insulation layer between the inner side of the rear end cover 450 and the inner lining insulation layer 900, because it will connect the end cover of the entire turbine generator, is not exposed, and has a small temperature difference in the heat dissipation direction.

[0065] It should be noted that the inner lining insulation layer 900 inside the furnace shell is cast in shape. First, the claw nails are welded to the inner side of the furnace wall 410, the inner side of the front cover 420, and the inner side of the rear cover 450. After placing the mold, the casting is carried out. After curing, the mold is removed to complete the production of the inner lining insulation layer 900.

[0066] In one possible implementation, two or more heat storage devices are mounted inside the furnace shell cavity via multiple mounting components. For example... Figure 4 As shown, each mounting component includes an outer support ring 740 and an inner support ring 750 arranged concentrically. The outer support ring 740 is located inside the cavity of the furnace wall 410. The outer side of the inner support ring 750 is fixedly connected (by welding) to the inner cylinder 730 of the multiple heat storage bodies 700, and the inner side of the outer support ring 740 is fixedly connected (by welding) to the inner cylinder 730 of the multiple heat storage bodies 700. That is, multiple heat storage devices are arranged around the inner support ring 750 and the outer support ring 740. Under the limiting action of the inner support ring 750 and the outer support ring 740, the positions of the multiple heat storage devices are relatively fixed.

[0067] Furthermore, to improve the relative positional stability of the inner support ring 750 and the outer support ring 740, multiple guide rods can be set between the outer side of the inner support ring 750 and the inner side of the outer support ring 740, thereby further ensuring that the two effectively fix the multiple heat storage bodies 700 in the middle.

[0068] Preferably, the outer support ring 740 and the inner support ring 750 can be made of thicker steel plates; the optimal thickness of the outer support ring 740 and the inner support ring 750 is 20mm, and the material is 310S to ensure the support effect.

[0069] Furthermore, each mounting assembly also includes an outer support block 741, which is fixedly installed between the outer support ring 740 and the inner insulation layer 900. The outer support block 741 is made of metal, using high-temperature resistant alloy steel with a material grade of not less than 2520 (310S) and a temperature resistance of not less than 1200℃.

[0070] Furthermore, there are three sets of installation components. The three sets of installation components are arranged evenly along the length of the heat storage body 700. They are suitable for supporting the two ends and the middle of the inner cylinder 730 of the heat storage body 700 respectively, so as to ensure the overall installation stability of the heat storage device inside the furnace shell cavity.

[0071] In one possible implementation, such as Figure 5 As shown, an ignition port 430 is provided in the middle of the front cover 420, and the ignition device 400 is inserted into the cavity of the furnace shell through the ignition port 430 (generally the insertion depth is 0-100mm); furthermore, the outer wall of the ignition device 400 is fixed to the flange 431 of the front cover 420; the ignition device 400 adopts an ignition gun. In the initial state, the ignition gun sprays open flame to ignite the gas in the furnace and raise the furnace temperature; when the furnace temperature rises to close to 1000℃, the ignition gun stops working.

[0072] In one possible implementation, it also includes: a main gas pipeline 100, the inlet ends of two or more high-pressure transmission pipelines 200 are all connected to the main gas pipeline 100, and the gas is suitable for entering each high-pressure transmission pipeline 200 through the main gas pipeline 100.

[0073] In one possible implementation, a centrifugal compressor 800 is installed at the beginning of the main gas pipeline 100; the centrifugal compressor 800 is suitable for pressurizing ultra-low concentration methane below the lower explosive limit to form high-pressure methane gas. The dried ultra-low concentration methane can achieve a simultaneous increase in pressure and temperature, which is beneficial for achieving a balance between the heat and temperature of oxidation.

[0074] Furthermore, the pressure of the gas after being pressurized by the centrifugal compressor 800 shall not exceed 2.5 MPa(a). The minimum pressure can be determined according to the actual application and the compression ratio of the centrifugal compressor 800; the temperature shall be controlled below 500℃. Strict control of the methane concentration of the gas entering the centrifugal compressor 800 is required, maintaining the methane volume concentration below 3.5%. Even if static electricity and sparks are generated during compression, an explosion will not occur because the methane concentration is below the explosion limit. If the methane volume concentration exceeds 3.5% or the oxidation temperature exceeds the design allowable range, the equipment must be shut down to ensure safety.

[0075] In one possible implementation, a flow regulating valve 110 is installed on the main gas pipeline 100. This is used for backflow control of ultra-low concentration methane gas, to mitigate the adverse effects of unstable methane extraction in coal mines. It also maintains a constant intake volume for the centrifugal compressor 800. That is, it automatically adjusts the combustion load when the pressure decreases to maintain a relatively constant pressure.

[0076] In one possible implementation, the main gas pipeline 100 is provided with a venting pipeline, which is equipped with a safety valve 120 and an electric regulating valve to enable regulated venting and overpressure venting.

[0077] It should be noted that when the methane concentration in coal mine gas is high, the gas contains a large amount of water and has a low calorific value, which can cause ignition difficulties and temperature imbalances, severely affecting the system's thermal efficiency. Therefore, a gas-water separator needs to be installed at the front end of the centrifugal compressor 800 to remove a large amount of water and impurities from the gas, obtaining dry, ultra-low concentration gas. This prevents impurities from entering the subsequent turbine generator and affecting its operational safety, and also prevents a large amount of water from being entrained in the gas due to pressurization and temperature rise. Conversely, if the methane volume concentration in the coal mine gas is low, and a high-pressure preheater 230 is installed, the temperature rise of the centrifugal compressor 800 is needed to increase the temperature. In this case, there is no liquid water present, so a gas-water separator is not required.

[0078] A cooling heat exchanger can be installed at the front end of the centrifugal compressor 800 to deliver the cooled, low-concentration methane gas to the inlet of the centrifugal compressor 800, thereby maintaining the stability of the inlet gas flow and the operational stability of the centrifugal compressor 800. No cooling system is installed at the rear end of the centrifugal compressor 800, and the final temperature of the compressed methane gas is the same as the temperature of the gas after natural compression.

[0079] When it is necessary to install both a gas-liquid separator and a cooling heat exchanger at the front end of a centrifugal compressor 800, it is preferable to install the cooling heat exchanger at the front end of the gas-liquid separator. After the gas is cooled, gas-liquid separation is performed, which helps to save energy consumption in the compression process.

[0080] The methane concentration of the gas at the front end of the centrifugal compressor 800 can be adjusted in the reverse direction according to the temperature rise of the final centrifugal compressor 800 compression, maintaining a 1% margin of methane concentration within the explosive limits at the corresponding temperature. Different compression ratios result in different gas temperature rises, and different gas temperatures correspond to different lower explosive limits. It is necessary to determine the lower explosive limit value based on the actual temperature rise and then retain a certain safety margin.

[0081] This application presents a novel coal mine gas power generation technology to replace traditional integrated gas turbines, steam turbines, and internal combustion engines. Currently, the utilization of ultra-low concentration methane is limited to indirect methods. The first method involves mixing it into exhaust air and introducing it into a counter-current regenerative exhaust air oxidation unit. The second method, when the concentration of low-concentration methane in the relatively high-concentration portion of the coal mine is significantly higher than 9%, involves mixing a portion of low-concentration methane (3-8%) into it, controlling the final concentration to above 8%, so that the low-concentration methane generator unit can operate normally. The third method utilizes direct combustion technology.

[0082] The first method, indirect utilization by mixing with exhaust gas, suffers from problems such as gas escape, low heat extraction efficiency, high system resistance, high operating electricity costs, and high investment with low returns. The second method, partial mixing with higher concentration gas, involves requirements for the mixed concentration and limitations on the volume of the higher-concentration low-concentration gas. Often, complete mixing is impossible, leading to an unstable source of the mixed low-concentration gas, significantly reducing the unit's operating efficiency and the overall utilization rate of the gas. The third method, while simpler, more effective, and more efficient than the first, still suffers from significant drawbacks if the project's investment structure and utilization method are the same as the first method: converting chemical energy into high-temperature flue gas, which then generates steam to drive a turbine for power generation. This energy conversion path is long and complex, resulting in high investment and operating costs. Ultimately, this will still affect the project's development and application. Furthermore, the small scale of current individual ultra-low concentration gas projects in coal mines leads to long-term emissions of large amounts of ultra-low concentration gas, impacting the atmospheric environment.

[0083] Conventional oxidation combustion furnaces operate in a high-temperature oxidation environment at atmospheric pressure. The mixed gas entering the furnace is also at atmospheric pressure (generally not exceeding 10 kPa), and the high-temperature flue gas generated is also at atmospheric pressure. This environment cannot directly drive a gas turbine or turbine generator. Instead, it requires heat conversion through a waste heat boiler. The heat from the high-temperature flue gas is transferred to the waste heat boiler, which then generates steam. This steam is then used to generate electricity through a steam turbine generator set (driving the turbine to power the generator). This type of project involves numerous supporting equipment, multiple heat conversion stages, a long process, and high levels of expertise, requiring highly skilled operators. This significantly increases operating costs, reducing the overall economic viability of the project. Increased heat loss and low power generation efficiency further complicate the investment structure (because the steam generated by the steam turbine generator set needs to pass through a large cooling system to turn the exhaust steam into condensate, which is then recycled back into the waste heat boiler to generate steam again to drive the turbine).

[0084] This application addresses the serious problems of existing indirect and direct utilization technologies for ultra-low concentration methane, such as long conversion paths, low power generation efficiency, small scale, high investment and operating costs, by first pressurizing and then performing comprehensive combustion and oxidation of the methane gas. This application directly pressurizes and oxidizes low-concentration methane gas before supplying it to a turbine generator for utilization, ensuring complete oxidation of the methane gas, preventing gas escape, and eliminating unstable gas supply. Furthermore, the energy conversion path and processes in the entire utilization of low-concentration methane gas are short and simple.

[0085] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A high pressure oxidation apparatus for low concentration gas, characterized by, The utility model relates to a high-pressure gas supply system, comprising: a centrifugal compressor, a high-pressure gas supply pipeline and a high-pressure gas furnace; the centrifugal compressor is connected with the gas inlet end of the high-pressure gas supply pipeline, and is suitable for pressurizing and conveying gas to the high-pressure gas supply pipeline; the high-pressure gas furnace comprises a furnace shell, a heat storage device and an ignition device; the furnace shell is provided with a gas inlet for entering gas and a gas outlet for outputting high-temperature flue gas; the gas outlet end of the high-pressure gas supply pipeline is connected with the gas inlet for conveying gas into the furnace shell; the gas outlet is connected with the high-temperature flue gas inlet end of a turbine generator; the heat storage device is arranged in the cavity of the furnace shell, and the two ends of the heat storage device are opposite to the gas inlet and the gas outlet respectively, so that the gas entering from the gas inlet flows through the heat storage device and enters the cavity of the furnace shell for high-temperature oxidation; the ignition device is arranged on the side wall of the furnace shell, and the ignition end of the ignition device is located in the cavity of the furnace shell; the heat storage device comprises a front guide fluid, a heat storage body and a rear guide fluid arranged in sequence; one end of the front guide fluid away from the heat storage body is opposite to the gas inlet, and one end of the rear guide fluid away from the heat storage body is opposite to the gas outlet; the inner side of the heat storage body is provided with an inner cylinder, the two ends of the front guide fluid and the rear guide fluid are fixed with the two ends of the inner cylinder respectively, a plurality of perforations are formed in the side wall of the front guide fluid, the rear guide fluid and the inner cylinder, and one end of the inner cylinder connected with the front guide fluid is arranged in a closed structure; two or more heat storage devices are arranged in the cavity of the furnace shell through a plurality of mounting assemblies; each mounting assembly comprises an outer support ring and an inner support ring arranged with the same center; a plurality of heat storage devices are arranged around the inner support ring and the outer support ring.

2. The high pressure oxidation apparatus for low concentration gas according to claim 1, wherein A cut-off valve is arranged on the high-pressure gas supply pipeline.

3. The high pressure oxidation apparatus for low concentration gas according to claim 2, wherein A dry-type flame arrester is arranged on the high-pressure gas supply pipeline, and the cut-off valve and the dry-type flame arrester are arranged in sequence along the flow direction of the gas in the high-pressure gas supply pipeline.

4. The high pressure oxidation apparatus for low concentration gas according to claim 1, wherein The heat storage body is a tubular structure rolled from a metal wire mesh.

5. The high pressure oxidation apparatus for low concentration gas according to claim 1, wherein The main bodies of the front guide fluid and the rear guide fluid are both in the shape of a circular truncated cone, and the large-diameter end of the front guide fluid and the large-diameter end of the rear guide fluid are both close to the heat storage body.

6. The high pressure oxidation apparatus for low concentration gas according to any one of claims 1 to 4, characterized by There are two or more high-pressure gas supply pipelines, and the number of high-pressure gas supply pipelines is the same as and corresponds to the number of heat storage devices.

7. The high pressure oxidation apparatus of low concentration gas according to claim 6, wherein Further comprising: a total gas pipeline, the gas inlet end of each high-pressure gas supply pipeline is communicated with the total gas pipeline, the centrifugal compressor is installed at the beginning end of the total gas pipeline, and the gas is suitable for entering each high-pressure gas supply pipeline through the total gas pipeline.

8. The high pressure oxidation apparatus for low concentration gas according to claim 7, wherein A flow regulating valve is arranged on the total gas pipeline.

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