High-pressure oxidation device for low-concentration gas

Abstract

The invention relates to a high-pressure oxidation device for low-concentration gas. The high-pressure oxidation device 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 pressurizing gas and then conveying the 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 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 gas into the furnace shell; the gas outlet is suitable for being connected with a high-temperature flue gas inlet end of a turbine generator; the heat storage device is arranged in the cavity of the furnace shell, the two ends of the heat storage device are opposite to the gas inlet and the gas outlet respectively, and gas entering from the gas inlet flows through the heat storage device and enters the cavity of the furnace shell to be subjected to 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.

Description

Technical Field

[0001] The present application relates to the technical field of low-concentration gas utilization, and in particular to a high-pressure oxidation device for low-concentration gas. Background Art

[0002] In modern coal mining, many coal seams produce associated coalbed methane (CBM). During coal mining, the CBM needs to be extracted in advance or during the mining process. However, due to blockage and air leakage, air can mix with the CBM, forming a CBM-air mixture known as coal mine methane (CMM). Mine exhaust gas (also known as exhaust air) with a methane concentration below 0.75% has a high flow rate and low concentration. Direct discharge would seriously pollute the air. Therefore, research on low-concentration coal mine methane utilization technology is of great significance for improving gas utilization, reducing coal gas emissions, and alleviating gas pollution to the atmosphere. Summary of the Invention

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

[0004] According to one aspect of the present application, a high-pressure oxidation device for low-concentration gas is provided, comprising: a centrifugal compressor, a high-pressure transmission pipeline, and a high-pressure oxidation furnace; The centrifugal compressor is connected to the air inlet end of the high-pressure transmission pipeline and is suitable for pressurizing the gas and then transmitting it into the high-pressure transmission pipeline; The high-pressure oxidation furnace includes: a furnace shell, a heat storage device and an ignition device; the furnace shell is provided with an air inlet for gas and an air outlet for high-temperature flue gas; the outlet end of the high-pressure transmission pipeline is connected to the air inlet for transmitting gas into the furnace shell; the air outlet is connected to the high-temperature flue gas inlet of the turbine generator; The heat storage device is arranged inside the cavity of the furnace shell, and 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; The ignition device is arranged 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.

[0005] In a possible implementation, a shut-off valve is provided on the high-pressure delivery pipeline.

[0006] In a possible implementation, a dry flame arrester is provided on the high-pressure transmission pipeline, and the shut-off valve and the dry flame arrester are arranged in sequence along the flow direction of the gas in the high-pressure transmission pipeline.

[0007] In one possible implementation, the heat storage device includes: a leading fluid, a heat storage body, and a trailing fluid connected in sequence; One end of the leading fluid away from the heat storage body faces the air inlet, and one end of the trailing fluid away from the heat storage body faces the air outlet.

[0008] In a possible implementation, the heat storage body is a tubular structure formed by winding a wire mesh.

[0009] In a possible implementation, the main bodies of the leading fluid and the trailing fluid are both frustum structures, and the large-diameter ends of the leading fluid and the trailing fluid are both close to the heat storage body.

[0010] In a possible implementation, there are two or more high-pressure delivery pipes, and there are two or more heat storage devices inside the furnace shell; the number of high-pressure delivery pipes is the same as the number of heat storage devices and they are connected in one-to-one correspondence.

[0011] In a possible implementation, it further includes: a main gas pipeline, the intake ends of two or more of the high-pressure delivery pipes are all communicated with the main gas pipeline, a centrifugal compressor is installed at the beginning end of the main gas pipeline, and the gas is suitable for entering each high-pressure delivery pipe through the main gas pipeline.

[0012] In a possible implementation, a flow regulating valve is provided on the main gas pipeline.

[0013] Advantageous effects: The centrifugal compressor is connected to the intake end of the high-pressure delivery pipe, and is suitable for pressurizing the gas to enable it to have the power to drive the turbine blades of the turbine generator to rotate; the high-pressure delivery pipe is suitable for delivering the gas to the inside of the furnace shell of the high-pressure oxidation furnace, and the high-pressure oxidation furnace is suitable for burning and oxidizing the gas. The oxidized flue gas enters the turbine generator from the air outlet of the furnace shell. The turbine generator generates electricity through the process of converting the kinetic energy of the flue gas into mechanical rotational kinetic energy and then converting the mechanical energy into electrical energy. The two ends of the heat storage device are respectively communicated with the air inlet of the furnace shell and the air outlet of the furnace shell, so that the gas entering from the air inlet flows through the heat storage device and then enters the cavity inside the furnace shell for high-temperature oxidation, and then flows out from the heat storage device to the air outlet after oxidation. The role of the heat storage device here is to increase the heat and mass transfer process at high temperatures and activate the reaction chain through wall collisions, so that all unburned gas can be burned out here. This application has developed a new process for coal mine gas power generation, effectively utilizes the flue gas formed by pressurizing and burning and oxidizing low-concentration gas and sending it into the turbine generator, and avoids energy waste and environmental pollution caused by directly discharging low-concentration gas to the outside.

[0014] According to the following detailed description of the exemplary embodiments with reference to the accompanying drawings, other features and aspects of the present application will become clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings included in and forming a part of the specification illustrate exemplary embodiments, features, and aspects of the present application together with the specification, and are used to explain the principles of the present application.

[0016] Figure 1 Structural connection diagram of a high-pressure oxidation device for low-concentration gas showing an embodiment of the present application; Figure 2 Cross-sectional view of a high-pressure oxidation furnace showing an embodiment of the present application; Figure 3 Showing Figure 2 Partial enlarged view of; Figure 4 Longitudinal sectional view of a high-pressure oxidation furnace showing an embodiment of the present application; Figure 5 Side view of a high-pressure oxidation furnace showing an embodiment of the present application.

[0017] 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, leading fluid 710, regenerator 700, trailing fluid 720, inner cylinder 730, inner lining heat insulation layer 900, front end cover 420, furnace wall 410, rear end cover 450, total water inlet pipe 500, branch water inlet pipe 510, total water outlet pipe 600, branch water outlet pipe 610, outer support ring 740, inner support ring 750, outer support block 741. Detailed description of the specific embodiments

[0018] The following will describe in detail various exemplary embodiments, features, and aspects of the present application with reference to the drawings. The same reference numerals in the drawings denote elements having the same or similar functions. Although various aspects of the embodiments are shown in the drawings, the drawings do not have to be drawn to scale unless otherwise specified.

[0019] It should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application or simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present application.

[0020] In addition, 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 quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality of" means two or more unless otherwise specifically defined.

[0021] As used herein, the term "exemplary" means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" should not necessarily be construed as superior to or better than other embodiments.

[0022] In addition, for a better illustration of this application, numerous specific details are given in the following detailed implementation manners. Those skilled in the art should understand that this application can also be implemented without some specific details. In some instances, methods, means, elements, and circuits well-known to those skilled in the art are not described in detail so as to highlight the gist of this application.

[0023] Figure 1 Structure connection diagram of a high-pressure oxidation device for low-concentration gas in an embodiment of this application; Figure 2 Cross-sectional view of a high-pressure oxidation furnace in an embodiment of this application; Figure 3 Show Figure 2 Partial enlarged view of; Figure 4 Longitudinal sectional view of a high-pressure oxidation furnace in an embodiment of this application; Figure 5 Side view of a high-pressure oxidation furnace in an embodiment of this application. As Figure 1 shown, a high-pressure oxidation device for low-concentration gas includes: a centrifugal compressor 800, a high-pressure delivery pipeline 200, and a high-pressure oxidation furnace 300; the centrifugal compressor 800 is connected to the intake end of the high-pressure delivery pipeline 200 and is adapted to pressurize the gas and deliver it into the high-pressure delivery pipeline 200; the high-pressure oxidation furnace 300 includes: a furnace shell, a heat storage device, and an ignition device 400; the furnace shell is provided with an intake port 421 for the gas to enter and an outlet port 452 for the output of high-temperature flue gas; the outlet end of the high-pressure delivery pipeline 200 is connected to the intake port 421 and is adapted to deliver the gas into the furnace shell; the outlet port 452 is adapted to be connected to the high-temperature flue gas inlet end of a turbine generator; the heat storage device is arranged inside the cavity of the furnace shell and both ends of the heat storage device are respectively communicated with the intake port 421 and the outlet port 452, so that the gas entering from the intake port 421 flows through the heat storage device and enters the cavity of the furnace shell for high-temperature oxidation; the ignition device 400 is arranged on the side wall of the furnace shell, and the ignition end of the ignition device 400 is located inside the cavity of the furnace shell.

[0024] Here, it should be noted that the centrifugal compressor 800 is connected to the intake end of the high-pressure transmission pipeline 200, which is suitable for pressurizing the gas in the mine, enabling it to have the power to drive the turbine blades of the turbine generator to rotate; the high-pressure transmission pipeline 200 is suitable for transporting the gas in the mine to the inside of the furnace shell of the high-pressure oxidation furnace 300, and the high-pressure oxidation furnace 300 is suitable for burning and oxidizing the gas in the mine. The oxidized flue gas enters the turbine generator from the air outlet 452 of the furnace shell. When the flue gas shoots into the turbine in the turbine generator, the kinetic energy of the flue gas is converted into the kinetic energy on the turbine blades. After being impacted by the flue gas, the turbine blades start to rotate, and the rotational motion is transmitted to the generator through the bearing and the shaft. The magnetic field between the rotor and the stator in the generator interacts to generate electric energy. The ignition device 400 uses normal-pressure gas for open-flame ignition and gradual heating at the initial stage when the equipment is put into operation without increasing the pressure. Both ends of the heat storage device are respectively communicated with the air inlet 421 and the air outlet 452 of the furnace shell, so that the gas in the mine entering from the air inlet 421 flows through the heat storage device and then enters the cavity inside the furnace shell for high-temperature oxidation. After oxidation, it then flows out of the heat storage device to the air outlet 452. The role of the heat storage device here is to increase the heat and mass transfer process at high temperatures and activate the reaction chain through wall collisions, enabling all unburned gas in the mine to burn out here. This application has developed a new process for generating electricity from gas in the mine, sending the flue gas formed by pressurizing and then burning and oxidizing low-concentration gas in the mine into the turbine generator for utilization, avoiding energy waste caused by directly discharging low-concentration gas to the outside.

[0025] In a possible implementation, a cut-off valve 210 is provided on the high-pressure transmission pipeline 200. The cut-off valve 210 is suitable for controlling the on-off of the gas flow in the high-pressure transmission pipeline 200. When a fault or fire occurs at the rear end, the cut-off valve 210 can be promptly shut off to prevent the gas in the mine from continuing to be transmitted.

[0026] Furthermore, there are two cut-off valves 210 in total, and the two cut-off valves 210 are arranged adjacent to each other in sequence along the gas flow direction in the high-pressure transmission pipeline 200.

[0027] In a possible implementation, a dry flame arrester device 220 is provided on the high-pressure transmission pipeline 200, and the cut-off valve 210 and the dry flame arrester device 220 are arranged in sequence along the gas flow direction in the high-pressure transmission pipeline 200. Here, it should be noted that the dry flame arrester device 220 is a safety device for preventing the spread of flames of flammable gases. If a deflagration occurs in the high-pressure oxidation furnace 300, it can prevent the flame from flowing back and invading the high-pressure transmission pipeline 200, curbing the spread of the flame in the pipeline, while effectively utilizing the low-concentration gas in the mine to improve the safety performance of the overall equipment. The pressure-bearing capacity of the dry flame arrester device 220 is set according to the 4.0 MPa grade and is installed before the high-pressure preheater 230 in an area where the temperature is lower than 500 °C.

[0028] In a possible implementation, it further includes: a high-pressure preheater 230; one end of the high-pressure delivery pipeline 200 is connected to the air inlet of the high-pressure preheater 230, and the air outlet of the high-pressure preheater 230 communicates with the air inlet 421 of the high-pressure oxidation furnace 300; it should be noted that whether to install the high-pressure preheater 230 can be determined according to the actual design conditions. If the methane concentration of the gas is lower than 3%, the high-pressure preheater 230 must be set; when the methane concentration of the gas is controlled very close to 5% (lower explosion 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 oxidation furnace 300 to achieve the self-thermal balance of the high-pressure oxidation furnace 300.

[0029] Furthermore, the high-pressure preheater 230 includes a heat exchange tube and a high-temperature resistant outer shell arranged coaxially; the heat exchange tube is arranged inside the cavity of the high-temperature resistant outer shell; one end of the high-pressure delivery pipeline 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 oxidation furnace 300; the gas enters the high-pressure oxidation furnace 300 through the heat exchange tube in the high-pressure preheater 230, and the high-temperature resistant outer shell is provided with a medium inlet 232 suitable for the incoming flue gas and a medium outlet 231 suitable for the outgoing flue gas to introduce the flue gas. The flue gas enters the high-temperature resistant outer shell and exchanges heat with the gas in the heat exchange tube to increase the temperature of the gas.

[0030] It should be noted that considering that the heat exchange tube bears a large working pressure (generally designed to be greater than 2.0 MPa), and at the same time, the problem of thermal expansion and contraction caused by the temperature change between the high-temperature preheating environment and normal temperature and during the preheating process needs to be considered. The heat exchange tube is preferably a spiral groove heat exchange tube. At the same time, in order to prevent the gas from being prematurely oxidized during the preheating process and affecting the temperature resistance of the equipment itself, the heat exchange tube is made of a high-temperature resistant material. Preferably, the material grade of the heat exchange tube is selected above grade 310S or an alloy steel material with a temperature resistance above 1200 °C, fully considering the temperature rise caused by the premature oxidation of the ultra-low concentration gas during the preheating process; the inner diameter of the heat exchange tube is not greater than 12 mm, and the inner diameter of the heat exchange tube is controlled below the detonation critical diameter (12 mm) to prevent the acceleration of flame propagation caused by the premature oxidation of methane and the occurrence of detonation.

[0031] When a high-pressure preheater 230 is provided, the medium inlet 232 is adapted to be connected to the outlet of the turbogenerator, and the back pressure is utilized to overcome the resistance so as to introduce the flue gas at the outlet of the turbogenerator into the high-pressure preheater 230, or the medium inlet 232 is directly connected to the outlet 452 of the high-pressure oxidation furnace 300 through a pipeline so as to directly recycle a part of the flue gas output by the high-pressure oxidation furnace 300 into the high-pressure preheater 230. The high-pressure preheater 230 can preheat the compressed gas with the high-temperature flue gas after oxidation and can be used to control the oxidation temperature of the high-pressure oxidation furnace 300; ensure that the temperature of the flue gas formed after the gas is oxidized is lower than 1100 °C (autoignition temperature) and higher than 900 °C. When the oxidation temperature rises, the preheating temperature can be appropriately reduced; when the oxidation temperature drops, the preheating temperature can be appropriately increased to always keep the oxidation temperature relatively constant. The preheating temperature is also related to the methane concentration of the gas. When the methane volume concentration of the gas is too low and the oxidation temperature of 900 °C cannot be maintained, it is necessary to increase the heat exchange amount of preheating and raise the initial temperature to ensure the oxidation ambient temperature. When the methane concentration of the gas can meet the oxidation temperature requirement, the heat exchange load of preheating can be reduced, or even the heat exchange function of the preheater can be stopped.

[0032] In a possible implementation manner, it further includes: a gas distributor 240. The gas distributor 240 is arranged between the high-pressure delivery pipeline 200 and the high-pressure oxidation furnace 300. The inlet of the gas distributor 240 is connected to the outlet end of the high-pressure delivery pipeline 200, and the outlet of the gas distributor 240 is connected to the inlet 421 of the furnace shell; under the action of the gas distributor 2, the uniformity of the gas entering the high-pressure oxidation furnace 300 is improved. It should also be noted that when the gas concentration is low, the gas distributor 240 can be omitted.

[0033] In a possible implementation manner, 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 be blocked, a convenient detachable expansion joint clamp is provided for convenient disassembly and maintenance.

[0034] It should be noted that when both the gas distributor 240 and the high-pressure preheater 230 are configured, the gas distributor 240 is arranged at the rear end of the high-pressure preheater 230, that is, the high-pressure preheater 230 and the gas distributor 240 are successively arranged between the outlet end of the high-pressure delivery pipeline 200 and the inlet 421 of the furnace shell.

[0035] In a possible implementation manner, as Figure 2As shown in the figure, the heat storage device includes: a front guide fluid 710, a heat storage body 700, and a rear guide fluid 720 arranged in sequence along the length direction of the furnace shell; one end of the front guide fluid 710 away from the heat storage body 700 is opposite to the air inlet 421, and one end of the rear guide fluid 720 away from the heat storage body 700 is opposite to the air outlet 452. Here, it should be noted that the front guide fluid 710 is suitable for timely delivering the gas gas entering the air inlet 421 to the heat storage body 700. Since the heat storage body 700 is not a closed structure and there are opening gaps on its side wall, the gas gas will overflow from the side wall of the heat storage body 700 and flow into the cavity inside the furnace shell after entering the heat storage body 700. The gas gas burns and oxidizes inside the cavity of the furnace shell, and after oxidation, it flows into the heat storage body 700 again, finally enters the rear guide fluid 720 and flows out from the air outlet 452; during the process of the gas gas entering and leaving the high-pressure oxidation furnace 300, it continuously impacts the heat storage body 700 to improve the oxidation efficiency; at the same time, the heat storage body 700 can appropriately reduce the flow rate of the gas gas and increase the residence time of the gas gas inside the furnace shell, so that all unburned gas gas can be burned out inside the furnace shell, ensuring that the gas gas is fully burned and oxidized.

[0036] In a possible implementation manner, the heat storage body 700 is a tubular structure formed by winding metal wire meshes. It should be noted that the inner diameter of the gaps of the metal wire meshes is less than 2 mm, and it is wound to form a multi-layer staggered structure, which can enable the oxidation reactants inside the furnace shell to collide multiple times while passing through the wire mesh layers, and can also filter the gas gas to prevent the falling refractory materials from being carried to the air outlet 452.

[0037] In a possible implementation manner, the thickness of the heat storage body 700 ranges from 100 to 300 mm; here, it should be noted that the specific number of layers and thickness of the heat storage body 700 are determined according to the concentration fluctuation range of the gas gas. Generally, when the concentration of the gas gas is low and often falls below the lean combustion limit, the number of layers and thickness of the heat storage body 700 can be reduced. The material of the heat storage body 700 is optimally 27L7Mo2, and the temperature resistance grade is 1400 °C.

[0038] In a possible implementation manner, 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 and is suitable for supporting the heat storage body 700 to avoid deformation and fracture of the heat storage body 700, prevent impurities from entering the subsequent turbine generator and damage to subsequent equipment; the main body of the inner cylinder 730 is a porous cylindrical structure, and the gas gas enters and exits the inner cylinder 730 through multiple holes on the inner cylinder 730. The material of the inner cylinder 730 is alloy steel above 310S. The punching diameter on the inner cylinder 730 is less than or equal to 1 mm.

[0039] In a possible implementation, the main bodies of the leading fluid 710 and the trailing fluid 720 are both hollow frustum structures, and both circular surface ends of the leading fluid 710 and the trailing fluid 720 are open structures. A plurality of punching holes are provided on the side walls of the leading fluid 710 and the trailing fluid 720, so that the gas can enter and exit the leading fluid 710 and the trailing fluid 720 through the punching holes on the leading fluid 710 and the trailing fluid 720. And the large-diameter ends of the leading fluid 710 and the trailing fluid 720 are both in contact with the regenerator 700.

[0040] Further, as Figure 2 shown, the leading fluid 710 and the trailing fluid 720 are respectively fixed to both ends of the inner cylinder 730 inside the regenerator 700. Preferably, the leading fluid 710 and the trailing fluid 720 are respectively fixed to both ends of the inner cylinder 730 by welding. The leading fluid 710 is placed in the inner liner heat insulation layer 900 inside the front end cover 420; the trailing fluid 720 is embedded in the inner liner heat insulation layer 900 inside the rear end cover 450; and there are reserved gaps between the leading fluid 710, the trailing fluid 720 and the inner wall of the channel to avoid the stress influence caused by expansion.

[0041] In a possible implementation, one end of the inner cylinder 730 connected to the leading fluid 710 is set as a closed structure, so that the gas first contacts the regenerator 700 through the leading fluid 710. After the gas is oxidized outside the inner cylinder 730, it continues to enter the inner side of the inner wall of the inner cylinder 730 through the regenerator 700, and enters the trailing fluid 720 through the inner channel of the inner cylinder 730, and finally is released from the air outlet 452.

[0042] The lengths of the leading fluid 710 and the trailing fluid 720 are designed according to the normal streamline ratio and determined based on the principle of reducing the resistance caused by the diameter change. Preferably, the optimal ratio of the length of the leading fluid 710, the length of the regenerator 700 and the length of the trailing fluid 720 is 1:10:1.5.

[0043] In a possible implementation, there are two or more high-pressure transmission pipelines 200, and there are two or more regenerator devices inside the furnace shell; the number of the high-pressure transmission pipelines 200 is the same as the number of the regenerator devices and they are in one-to-one correspondence and communication. It should be noted that, in order to improve the oxidation efficiency of the gas, a plurality of regenerator devices are arranged inside the furnace shell, and the plurality of high-pressure transmission pipelines 200 are suitable for respectively transporting the gas to the plurality of regenerator devices. The pressure resistance level of the high-pressure transmission pipeline 200 is 4.0 MPa.

[0044] In a possible implementation, each high-pressure delivery pipeline 200 is further provided with a regulating valve for regulating the gas flow rate in the high-pressure delivery pipeline 200, a flow meter for detecting the gas flow rate in the high-pressure delivery pipeline 200, a concentration meter for detecting the methane concentration in the high-pressure delivery pipeline 200, and a thermometer for detecting the gas temperature in the high-pressure delivery pipeline 200. The regulating valve, the flow meter, the concentration meter, and the thermometer are arranged in sequence along the flow direction of the gas in the high-pressure delivery pipeline. The concentration meter and the thermometer need to be observed simultaneously, and the control principle is to control the methane concentration below the explosion limit corresponding to the temperature to prevent backfire or explosion in the pipeline caused by static electricity, sparks, etc. during the transportation in the high-pressure delivery pipeline. The regulating valve is used to adjust the pressure and combustion load of the high-pressure delivery pipeline 200, and the adjustment principle is to make the gas flow rates in all high-pressure delivery pipelines 200 as identical as possible.

[0045] Further, the main body of the furnace shell is in a cylindrical structure and is hollow inside, and the furnace shell can withstand a pressure exceeding 4 MPa. The structures of each regenerator are the same. As Figure 3 shown, each regenerator is arranged in a ring shape evenly in sequence along the circumferential direction of the furnace shell.

[0046] In a possible implementation, the furnace shell includes: a front end cover 420, a furnace wall 410, and a rear end cover 450 that are fixedly connected; the main body of the furnace wall 410 is in a cylindrical structure and is provided with a cavity with openings at both ends, and the front end cover 420 and the rear end 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 end cover 420 is provided with more than two air inlets 421, and the rear end cover 450 is provided with more than two air outlets 452. The front guide fluid 710 and the rear guide fluid 720 of each regenerator respectively correspond to one air inlet 421 and one air outlet 452, and the body length directions of each regenerator are parallel to each other.

[0047] Further, the front end cover 420 is provided with six air inlets 421, and the six air inlets 421 are arranged in sequence around the circumferential direction of the front end cover 420; the rear end cover 450 is provided with six air outlets 452, and the six air outlets 452 are arranged in sequence around the circumferential direction of the rear end cover 450; there are six regenerators in total; the six air inlets 421, the six regenerators, and the six air outlets 452 are arranged in one-to-one correspondence. A connecting flange 451 is provided on the outer edge of the rear end cover 450, which is suitable for connecting to a turbine generator.

[0048] In a possible implementation, the furnace wall 410 adopts a membrane water wall. There are multiple water flow channels inside the membrane water wall, which is suitable for cooling the furnace wall 410 by taking away the heat of the furnace wall 410 through cooling water. The high-pressure water that can withstand a pressure of 6.0 MPa is inside the furnace wall 410. It can ensure the safety of the equipment, avoid the thermal deformation of the furnace wall 410 and the reduction of the pressure-bearing capacity of the furnace wall 410 due to the high-temperature effect; the material of the furnace shell is pressure-bearing vessel steel (generally 16MnR is the best).

[0049] Further, it also includes: a main inlet pipe 500 and multiple sub-inlet pipes 510. The inlet ends of the multiple sub-inlet pipes 510 are connected to the main inlet pipe 500, and the outlet ends of the multiple sub-inlet pipes 510 are respectively connected to the multiple water flow channels of the furnace wall 410. The cooling water in the main inlet pipe 500 flows into the inside of the furnace wall 410 through the multiple sub-inlet pipes 510 in sequence.

[0050] Further, it also includes: a main outlet pipe 600 and multiple sub-outlet pipes 610. The outlet ends of the multiple sub-outlet pipes 610 are connected to the main outlet pipe 600, and the inlet ends of the multiple sub-outlet pipes 610 are respectively connected to the multiple water flow channels of the furnace wall 410. Each path of cooling water inside the furnace wall 410 enters the main outlet pipe 600 through the sub-outlet pipes 610 and then is discharged.

[0051] In a possible implementation, the inner wall of the furnace shell is attached with a lining heat insulation layer 900, as Figure 2 shown, the lining heat insulation layer 900 is provided on the inner side of the furnace wall 410, the inner side of the front end cover 420, and the inner side of the rear end cover 450, which is suitable for avoiding the cooling water inside the furnace wall 410 from affecting the oxidation temperature inside the furnace shell and eliminating the cold wall collision to destroy the reaction chain.

[0052] Further, the material of the lining heat insulation layer 900 is corundum mullite. The surface of corundum mullite is smooth, without burrs and without shedding, which plays an adiabatic effect, so that the temperature of the oxidation environment (the environment inside the furnace shell) of the ultra-low concentration gas remains within 1100 °C, and the temperature of the inner wall surface of the furnace shell reaches above 900 °C.

[0053] The thickness of the lining heat insulation layer 900 on the inner side of the furnace wall 410 is not less than 150 mm, and the optimal value is 300 mm; if the adiabatic degree does not meet the calculation requirements, a zirconium-containing aluminum silicate insulation layer can be added between the furnace wall 410 and the lining heat insulation layer 900 to further improve the adiabatic degree.

[0054] The thickness of the lining heat insulation layer 900 on the inner side of the front end cover 420 is not less than 150 mm. Further, a heat insulation layer 422 is provided between the inner side of the front end cover 420 and the lining heat insulation layer 900. The material of the heat insulation layer 422 is zirconium-containing aluminum silicate, and the thickness of the heat insulation layer 422 is not less than 300 mm to ensure the heat insulation effect of the front end cover 420.

[0055] The thickness of the inner lining heat insulation layer 900 on the inner side of the rear end cover 450 ranges from 200 to 300 mm. Further, there is no need to set a zirconium-containing aluminum silicate thermal insulation layer between the inner side of the rear end cover 450 and the inner lining heat insulation layer 900 because it will connect the end covers of the entire turbo generator, is not exposed, and the temperature difference in the heat dissipation direction is not large.

[0056] It should be noted that the inner lining heat insulation layer 900 on the inner side of the furnace shell is cast and formed; first, the claw nails are welded to the inner side of the furnace wall 410, the inner side of the front end cover 420, and the inner side of the rear end cover 450. After placing the mold, pouring is carried out, and the mold is removed after curing to complete the production of the inner lining heat insulation layer 900.

[0057] In a possible implementation manner, more than two heat storage devices are arranged inside the cavity of the furnace shell through a plurality of installation components. As Figure 4 shown, each installation component includes: an outer support ring 740 and an inner support ring 750 arranged concentrically; the outer support ring 740 is arranged inside the cavity of the furnace wall 410, and the outer side of the inner support ring 750 is fixedly connected (by welding) to the inner cylinders 730 of a plurality of heat storage bodies 700, and the inner side of the outer support ring 740 is fixedly connected (by welding) to the inner cylinders 730 of a plurality of heat storage bodies 700, that is, a plurality of heat storage devices are arranged in a surrounding manner between 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 a plurality of heat storage devices are relatively fixed.

[0058] Further, to improve the relative position stability of the inner support ring 750 and the outer support ring 740, a plurality of guide rods can be arranged between the outer side of the inner support ring 750 and the inner side of the outer support ring 740, so as to further ensure the effective fixation of the plurality of heat storage bodies 700 in the middle by the two.

[0059] Preferably, the outer support ring 740 and the inner support ring 750 can be processed from thick steel plates; the optimal thickness of the outer support ring 740 and the inner support ring 750 is 20 mm, and the material is 310S to ensure the support effect.

[0060] Further, each group of installation components further includes an outer support block 741, and the outer support block 741 is fixedly arranged between the outer support ring 740 and the inner lining heat insulation layer 900. The material of the outer support block 741 is a metal material, made of high-temperature resistant alloy steel, with a material grade not lower than 2520 (310S) and a temperature resistance grade not lower than 1200 °C.

[0061] Further, there are three groups of installation components in total, and the three groups of installation components are arranged in sequence and evenly along the body length direction of the heat storage body 700, which is suitable for respectively supporting the two ends and the middle of the inner cylinder 730 of the heat storage body 700 to ensure the installation stability of the overall heat storage device inside the cavity of the furnace shell.

[0062] In a possible implementation, as Figure 5 shown, an ignition port 430 is provided in the middle of the front end cover 420, and the ignition device 400 extends into the cavity of the furnace shell through the ignition port 430 (generally, the penetration depth is 0 - 100 mm); further, the outer side wall of the ignition device 400 is fixed to the flange 431 of the front end cover 420; the ignition device 400 uses an ignition gun. In the initial state, the ignition gun sprays out combustible gas and open flame to ignite the gas in the furnace and increase the temperature in the furnace; when the ambient temperature in the furnace rises to nearly 1000 °C, the ignition gun stops working.

[0063] In a possible implementation, it further includes: a main gas pipeline 100, and the inlet ends of more than two high-pressure delivery pipelines 200 are all connected to the main gas pipeline 100, and the gas is suitable for entering each high-pressure delivery pipeline 200 through the main gas pipeline 100.

[0064] In a possible implementation, a centrifugal compressor 800 is provided at the starting end of the main gas pipeline 100; the centrifugal compressor 800 is suitable for pressurizing ultra-low-concentration gas below the lower explosion limit to form high-pressure gas. The dried ultra-low-concentration gas can achieve the simultaneous increase of pressure and temperature, which is beneficial to achieving the balance of oxidation heat and temperature.

[0065] Further, the pressure of the gas after being pressurized by the centrifugal compressor 800 does not exceed 2.5 MPa (a), and the minimum value of the pressure can be determined according to the actual use and the compression ratio of the centrifugal compressor 800; the temperature is controlled within 500 °C. It is necessary to strictly control the methane concentration of the gas at the front end of the centrifugal compressor 800, and keep the methane volume concentration controlled within 3.5%. Even if static electricity and sparks are generated during the compression process, no explosion will occur because the methane concentration is lower than the explosion limit. Once the methane volume concentration exceeds 3.5% or the oxidation temperature exceeds the designed allowable range, the equipment needs to be stopped to ensure safety.

[0066] In a possible implementation, a flow regulating valve 110 is provided on the main gas pipeline 100. It is used for the reflux control of ultra-low-concentration gas and for adjusting the adverse effects brought by the instability of the gas extracted from coal mines. Keep the intake air volume of the centrifugal compressor 800 constant. That is, when the pressure decreases, the combustion load is automatically adjusted to maintain the relative constancy of the pressure.

[0067] In a possible implementation, a main gas pipeline 100 is provided with a relief pipeline, and a safety valve 120 and an electric control valve are provided on the relief pipeline to enable the adjustment of relief and achieve overpressure relief.

[0068] It should be noted that when the methane concentration in coal mine gas is relatively high, the water content in the gas is large and the calorific value is low, which will cause difficulties in ignition and imbalance of temperature, seriously affecting the thermal efficiency of the system. Therefore, a gas-liquid separator needs to be installed at the front end of the centrifugal compressor 800 to remove a large amount of moisture and impurities in the gas, obtaining dry ultra-low concentration gas to avoid impurities from entering the subsequent turbine generator and affecting the subsequent operation safety, and avoiding a large amount of moisture being entrained in the gas due to pressurization and temperature rise. On the contrary, if the volume concentration of methane in coal mine gas is relatively low and a high-pressure preheater 230 is installed, the temperature rise of the centrifugal compressor 800 needs to be utilized to increase the temperature. At this time, there is no liquid water, so there is no need to install a gas-liquid separator.

[0069] A cooling heat exchanger can be installed at the front end of the centrifugal compressor 800 to convey the low-concentration gas with reduced temperature into the inlet end of the centrifugal compressor 800 to maintain the stability of the gas flow at the inlet of the centrifugal compressor 800 and the working stability of the centrifugal compressor 800. For the rear end of the centrifugal compressor 800, no cooling link is installed, and the temperature of the finally compressed gas is the temperature of the naturally compressed gas.

[0070] When it is necessary to install both a gas-liquid separator and a cooling heat exchanger at the front end of the centrifugal compressor 800, it is preferred that the cooling heat exchanger is installed at the front end of the gas-liquid separator. The gas is cooled and then gas-liquid separated, which is beneficial to saving the energy consumption in the compression process.

[0071] The methane concentration of the gas at the front end of the centrifugal compressor 800 can be adjusted reversely according to the temperature rise of the final compression of the centrifugal compressor 800, so as to keep the methane concentration at a certain temperature within the explosion limit with a 1% margin. Different compression ratios have different gas temperature rises, and different gas temperatures of the gas correspond to different lower explosion limits. It is necessary to correspond to the value of the lower explosion limit according to the actual temperature rise value, and then reserve a certain safety margin.

[0072] This application replaces a new coal mine gas power generation process developed by traditional integrated gas turbines, steam turbines, internal combustion engines, etc. For ultra-low concentration gas, the current utilization method can only be an indirect utilization method. The first is to blend it into the exhausted air and enter the countercurrent regenerative exhausted air oxidation device. The second method is that when the concentration of low-concentration gas in a certain part of the coal mine is significantly higher than 9%, part of the low-concentration gas with a concentration of 3-8% is blended into it, and the concentration after blending is controlled to reach more than 8% so that the low-concentration gas generator set can generate electricity normally. The third method is to use direct combustion technology for utilization.

[0073] The first indirect utilization method of blending into the exhausted air has problems such as gas escape, low heat extraction efficiency, large system resistance, high operating electricity cost, and low investment efficiency. The second method of partially blending into higher-concentration gas involves the concentration requirements after blending and the limitation of the volume of low-concentration gas with higher concentration. It often cannot be fully blended and causes the instability of the low-concentration gas source after blending, resulting in a significant decline in the operating efficiency of the unit and the comprehensive utilization rate of gas. Although the third method is simpler, more effective, and more efficient than the first one, if it is used for power generation, the composition of the construction investment is the same as that of the first utilization method. Both convert chemical energy into high-temperature flue gas and then generate steam through heat exchange of the high-temperature flue gas to drive a steam turbine for power generation. The length of the energy conversion path is long and the links are cumbersome, and there are serious defects of large investment and high operating cost. Eventually, it will still affect the development and application of the project. Moreover, due to the small volume of individual projects of ultra-low-concentration gas in current coal mines, a large amount of ultra-low-concentration gas in coal mines is discharged for a long time, affecting the atmospheric environment.

[0074] In a conventional oxidation combustion furnace, the oxidation environment is high-temperature oxidation under normal pressure. The pressure of the mixed gas entering the oxidation furnace is also normal pressure (generally not exceeding 10 KPa), and the high-temperature flue gas formed by oxidation is also at normal pressure. It cannot directly drive a gas turbine or a turbo generator. It can only first perform heat energy conversion through a waste heat boiler, transfer the heat of the high-temperature flue gas to the waste heat boiler, then generate steam through the waste heat boiler, and then generate electricity through a steam turbine generator set (driving a steam turbine to drive a generator to generate electricity). Its project supporting equipment is numerous, the heat energy conversion links are many, the process is long, and the professionalism is strong. The requirements for operating personnel are high, resulting in a substantial increase in operating costs, thereby reducing the economy of the entire project; heat loss increases and power generation efficiency is low, and the investment structure is complex (because the steam after power generation by the steam turbine generator set needs to pass through a huge cooling system to turn the exhausted steam into condensed water and circulate into the waste heat boiler to generate steam again to drive the steam turbine).

[0075] However, the present application first pressurizes the gas and then conducts comprehensive combustion oxidation, which solves the serious problems in the existing indirect utilization and direct utilization technologies of ultra-low-concentration gas, such as long conversion path, low power generation efficiency, inability to construct due to small scale, and high investment and high operating cost. The present application directly pressurizes and combusts and oxidizes the low-concentration gas and then transports it to a turbo generator for utilization, and can ensure the complete oxidation of the gas, without the phenomenon of gas escape and without the phenomenon of unstable gas source. Moreover, the energy conversion path is short and the links are simple during the utilization process of the entire low-concentration gas.

[0076] The embodiments of the present application have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, the practical application, or the improvement of the technology in the market, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A high-pressure oxidation device for low-concentration gas, characterized in that, Including: A centrifugal compressor, a high-pressure conveying pipeline, and a high-pressure oxidation furnace; The centrifugal compressor is connected to the intake end of the high-pressure conveying pipeline and is suitable for pressurizing the gas and conveying it into the high-pressure conveying pipeline; The high-pressure oxidation furnace includes: a furnace shell, a heat storage device, and an ignition device; the furnace shell is provided with an intake port suitable for the gas to enter and an outlet port suitable for outputting high-temperature flue gas; the outlet end of the high-pressure conveying pipeline is connected to the intake port and is suitable for conveying the gas into the furnace shell; the outlet port is suitable for being connected to the high-temperature flue gas inlet end of a turbine generator; The heat storage device is arranged inside the cavity of the furnace shell, and both ends of the heat storage device are respectively opposite to the intake port and the outlet port, so that the gas entering from the intake port 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 inside the cavity of the furnace shell.

2. The high-pressure oxidation device for low-concentration gas as claimed in claim 1, wherein A cut-off valve is provided on the high-pressure conveying pipeline.

3. The high-pressure oxidation device for low-concentration gas as claimed in claim 2, wherein A dry flame arrester is provided on the high-pressure conveying pipeline, and the cut-off valve and the dry flame arrester are arranged in sequence along the flow direction of the gas in the high-pressure conveying pipeline.

4. The high-pressure oxidation device for low-concentration gas as claimed in claim 1, wherein, The heat storage device includes: a front guiding fluid, a heat storage body, and a rear guiding fluid arranged in sequence; One end of the front guiding fluid away from the heat storage body is opposite to the intake port, and one end of the rear guiding fluid away from the heat storage body is opposite to the outlet port.

5. The high-pressure oxidation device for low-concentration gas as claimed in claim 4, wherein, The heat storage body is a tubular structure formed by winding a metal wire mesh.

6. The high-pressure oxidation device for low-concentration gas as claimed in claim 4, wherein, The main bodies of the front guiding fluid and the rear guiding fluid are both in a frustum structure, and the large-diameter ends of the front guiding fluid and the rear guiding fluid are both close to the heat storage body.

7. The high-pressure oxidation device for low-concentration gas as claimed in any one of claims 1-6, characterized in that, There are two or more high-pressure conveying pipelines, and there are two or more heat storage devices arranged inside the furnace shell; the number of the high-pressure conveying pipelines is the same as that of the heat storage devices and they are connected in one-to-one correspondence.

8. The high-pressure oxidation device for low-concentration gas as claimed in claim 7, wherein Also including: A main gas pipeline, the intake ends of two or more high-pressure conveying pipelines are all connected to the main gas pipeline, the centrifugal compressor is installed at the beginning end of the main gas pipeline, and the gas is suitable for entering each high-pressure conveying pipeline through the main gas pipeline.

9. The high-pressure oxidation device for low-concentration gas as claimed in claim 8, wherein, A flow regulating valve is provided on the main gas pipeline.

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