Regenerative oxidation device and system for ultra-low concentration gas in coal mine

Abstract

The application discloses a kind of coal mine ultra-low concentration gas is with heat accumulation oxidation device and system, including shell, heat accumulator and direct combustion burner, wherein, the shell inside is sequentially arranged air chamber, heat accumulation room and combustion chamber from one side to the other side, heat accumulation room is at least divided into two regions, heat accumulator is set in heat accumulation room, heat accumulator is layered structure, sequentially set upper heat accumulation layer, middle heat accumulation layer and lower heat accumulation layer from the side close to combustion chamber to the side close to air chamber;Upper heat accumulation layer is inorganic non-metallic material, its high-temperature section is high-aluminum refractory material, medium-temperature section is mullite material, low-temperature section is cordierite material;Middle heat accumulation layer is metal heat accumulation material;Lower heat accumulation layer is composed of heat pipe array;Direct combustion burner is set on the side wall of combustion chamber, its gas inlet end is used to be connected with extraction gas pipeline;Air chamber side wall is provided with air inlet and air outlet.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of efficient utilization of ultra-low concentration gas, and particularly relates to a heat storage and oxidation device and system for coal mine ultra-low concentration gas. BACKGROUND

[0002] The statements herein merely provide background technology related to the present application, and do not necessarily constitute prior art.

[0003] Ultra-low concentration gas refers to coal mine gas with a methane concentration less than 7%, which mainly exists in goaf and air exhaust gas. The methane concentration of gas extracted by zone buried pipe is usually greater than 1%. Air exhaust gas is generated in the process of ventilation of coal mine roadway, and the methane concentration thereof is generally less than 0.75%. Ultra-low concentration gas cannot be directly used for power generation, and most of it is directly discharged into the air, which will cause greenhouse effect.

[0004] The gas heat storage and oxidation technology is a common method for treating ultra-low concentration gas. However, the flow and concentration of ultra-low concentration gas generated in coal mines fluctuate greatly, resulting in poor working condition stability. When heat storage and oxidation is performed, incomplete combustion of gas is prone to occur, and harmful substances such as CO are generated. In addition, due to the low concentration of ultra-low concentration gas, the heat generated by combustion is small, and it is difficult to ensure the stable operation of the system during the combustion process. Moreover, the existing heat storage body has poor temperature resistance and low thermal efficiency, and especially in the case of poor working condition stability, the service life is prone to be reduced, which leads to difficulty in popularization and application.

[0005] In addition, the ultra-low concentration gas to be treated needs to be uniformly mixed with air before entering the heat storage and oxidation device to ensure sufficient oxidation inside the heat storage and oxidation device. However, the flow of ultra-low concentration gas is large, and it needs to be mixed with a large amount of air, which makes it difficult to ensure uniform mixing, further exacerbating the incomplete combustion of gas. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a heat storage and oxidation device and system for coal mine ultra-low concentration gas.

[0007] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0008] In the first aspect, the present application provides a heat storage and oxidation device for coal mine ultra-low concentration gas, comprising a shell, a heat storage body and a direct combustion burner, wherein,

[0009] The shell is internally provided with a wind chamber, a heat storage chamber and a combustion chamber in sequence from one side to the other side. The heat storage chamber is at least divided into two regions. The heat storage body is arranged in the heat storage chamber. The heat storage body has a layered structure, and is provided with an upper heat storage layer, a middle heat storage layer and a lower heat storage layer in sequence from the side close to the combustion chamber to the side close to the wind chamber.

[0010] The upper heat storage layer is inorganic non-metallic material, the high-temperature section is high-aluminum refractory material, the medium-temperature section is mullite material, and the low-temperature section is cordierite material;

[0011] The middle heat storage layer is metal heat storage material; and the lower heat storage layer is composed of heat pipe array.

[0012] The direct combustion burner is arranged on the side wall of the combustion chamber, and the air inlet end is used for being connected with the gas extraction pipeline.

[0013] The side wall of the air chamber is provided with an air inlet and an air outlet.

[0014] The heat storage chamber and the combustion chamber adopt regular shapes such as cylinder and cuboid, so as to realize the multi-chamber independent segmentation of the heat storage body and the high-temperature oxidation combustion of the ultra-low concentration gas. The heat storage chamber is at least divided into two areas, and the heating oxidation of the ultra-low concentration gas and the heat recovery and heat storage of the high-temperature flue gas generated by combustion are respectively performed.

[0015] In the heat storage combustion device, the temperature in the combustion chamber is very high, and the temperature resistance of the metal heat storage material is poor. Therefore, the heat storage material in the heat storage combustion furnace is generally high-temperature resistant material such as ceramic. However, the heat conduction of the ceramic material is poor. When the high-temperature combustion gas is stored through the heat storage body, due to the large gas flow rate, the ceramic heat storage body is difficult to quickly absorb heat, resulting in high outlet air temperature, which is difficult to effectively utilize the waste heat, causing waste of heat. In addition, it is easy to cause the temperature of the ceramic heat storage body close to the combustion chamber to be very high, but the temperature of the ceramic heat storage body close to the air chamber is relatively low. When the gas-air mixed gas with a certain flow rate flows through the heat storage body in the low-temperature area, it is difficult to be effectively preheated, and then when it flows through the high-temperature section of the heat storage body, it is difficult to be fully heated and combusted, resulting in insufficient gas combustion.

[0016] In order to solve the above problems, the inventors design the heat storage body as a three-layer structure. The upper heat storage layer is inorganic non-metallic material, the high-temperature section is high-aluminum refractory material, the middle section is mullite material, and the low-temperature section is cordierite material; the middle heat storage layer is metal heat storage material; and the lower heat storage layer is heat pipe heat storage material.

[0017] The upper heat storage layer is closest to the combustion chamber, and the high-aluminum refractory material is arranged in the high-temperature section, which has high fire resistance and good slag resistance, can protect the heat storage body from high-temperature radiation, and is conducive to improving the overall service life of the heat storage body. The middle section adopts mullite material. Mullite has the advantages of high-temperature resistance, oxidation resistance, high specific heat capacity, high heat storage efficiency, low thermal expansion coefficient, etc. It can quickly absorb and release heat, store more heat, quickly cool down the high-temperature flue gas in the combustion chamber, and protect the following cordierite heat storage body, metal heat storage body and heat pipe.

[0018] The cordierite heat accumulator has a small thermal expansion coefficient, good corrosion resistance and resistance to rapid cooling and heating at a temperature below 1000 DEG C, and can maintain structural stability under sharp temperature changes, and is not easy to crack or deform, so that the structural stability of the entire heat accumulator can be maintained to improve the service life of the heat accumulator.

[0019] The inorganic non-metallic material heat accumulator has small volume, light weight, large specific surface area, high refractoriness, large heat transfer capacity, and small air flow passage resistance loss, which is more conducive to realizing low-oxygen combustion, making the furnace temperature uniform and heat transfer rapid, greatly reducing the oxidation loss and generation of NOx gas, and significantly improving the environmental protection and energy saving effect.

[0020] When the high-temperature flue gas flows through the upper heat storage layer, the temperature drops significantly, and it is difficult to effectively absorb the waste heat in the flue gas by using ceramic heat storage bodies again. Therefore, the middle heat storage layer is made of metal heat storage bodies. The heat storage performance of the metal heat storage bodies is general, and the high-temperature resistance is relatively large, but the thermal conductivity is high, which can quickly absorb the waste heat in the flue gas, further reduce the temperature of the flue gas, and the metal heat storage bodies have a price advantage and are simple to process.

[0021] The heat pipe structure is arranged at the position close to the air inlet of the heat storage body. The heat conduction capacity of the heat pipe is much higher than that of metal, which can further absorb and store the waste heat in the flue gas. Moreover, the metal heat storage body can transfer heat to the heat pipe, so that the medium in the heat pipe can be kept at a high temperature.

[0022] When the mixed gas of gas and air is introduced into the heat storage body again, it first flows through the heat pipe. Since the medium in the heat pipe is kept at a high temperature, the mixed gas can be quickly preheated. After flowing through the metal heat storage body, the mixed gas can be preheated better, so that the mixed gas can basically reach the ignition point when it flows through the upper heat storage layer, and then the oxidation process in the heat storage body is completed, thereby ensuring the safety of the low-concentration gas direct combustion in the combustion chamber.

[0023] The completion of the oxidation process in the heat storage body can inhibit the flame propagation speed, convert the explosion energy into stable combustion, avoid the accumulation of gas in the combustion chamber to cause the local gas concentration to be too high, and make the remaining gas in the combustion chamber be in a controllable combustion range.

[0024] Since the heat storage body generally adopts a honeycomb structure with high specific surface area, the contact between the heat storage body and the gas is more uniform and sufficient. When the gas can complete the oxidation process in the heat storage body, it can be seen that the combustion of the gas in the heat storage combustion chamber is more sufficient.

[0025] In some embodiments, the thickness ratio of the upper heat storage layer, the middle heat storage layer and the lower heat storage layer is 4-6:2-4:1-3.

[0026] Preferably, the thickness ratio of the high-temperature section, the medium-temperature section and the low-temperature section in the upper heat storage layer is 3-5:2-4:2-4.

[0027] In some embodiments, the heat pipes are arranged in parallel to the middle heat storage layer to form a heat pipe array; or the evaporation ends of the heat pipes are inserted into or through the middle heat storage layer, and the condensation ends extend out of the middle heat storage layer.

[0028] When the evaporation ends of the heat pipes are inserted into or through the middle heat storage layer, in addition to quickly absorbing the residual heat in the flue gas, the heat of the middle heat storage layer, and even the upper heat storage layer, can be better absorbed to heat and evaporate the working fluid in the heat pipes, so that the temperature of the condensation end of the heat pipe is higher, thereby achieving good preheating effect on the incoming air.

[0029] In some embodiments, the heat pipes are negative pressure heat pipes, normal pressure heat pipes or positive pressure heat pipes. The bottom of the heat storage oxidation device belongs to a low-temperature zone. By using the advantages of small heat exchange temperature difference, high heat transfer coefficient and low flow resistance of heat pipes, heat recovery is performed by using energy storage heat pipes, heat exchange is performed between the high-temperature tail gas end and the low-temperature incoming air by using heat transfer heat pipes. The heat in the low-temperature zone of the heat storage oxidation device is quickly recovered, the exhaust air temperature is further reduced, and the incoming air is quickly preheated.

[0030] The type of heat pipe is not limited to energy storage heat pipes and heat transfer heat pipes. The working medium storage form in the energy storage heat pipe includes but is not limited to sensible heat type, phase change type and chemical potential composite heat storage. The heat transfer working medium of the heat transfer heat pipe includes but is not limited to organic type, inorganic type and metal type.

[0031] In some embodiments, the side of the upper heat storage layer close to the combustion chamber is provided with corundum check bricks. The radiation of the high-temperature furnace to the heat storage body is reduced, and the stability of the heat storage body is increased.

[0032] In some embodiments, the type of the upper heat storage layer includes but is not limited to saddle ring type, sheet type, honeycomb type heat storage body, heat storage ball or heat storage pipe.

[0033] In some embodiments, the type of the middle heat storage layer includes but is not limited to pressed type, wire mesh type, woven type, rod type, block type or spherical type. The middle heat storage layer uses the advantages of high heat conduction performance, fast heat storage and release performance, good mechanical strength, low price and convenient size and size adjustment according to needs, to further improve the utilization efficiency of heat energy.

[0034] In some embodiments, the side wall of the combustion chamber is provided with a high-temperature heat bypass valve. The heat generated by the self-balancing oxidation combustion of gas is discharged through the high-temperature heat bypass valve for heat recycling.

[0035] In some embodiments, the number of the heat storage chambers is an odd number greater than 1, and the side wall of the air chamber is provided with an air inlet, an air outlet and a sweep air inlet.

[0036] The purge gas is a key link for guaranteeing purification efficiency, equipment life and operation safety.

[0037] In some embodiments, a secondary combustion device is arranged in the air chamber, the regenerative chamber, the combustion chamber or the high-temperature heat bypass pipeline to supplement air therein to ensure sufficient gas combustion, and the arrangement position of the secondary combustion device is determined through simulation experiments.

[0038] In the second aspect, the application provides a regenerative oxidation system for coal mine ultra-low concentration gas, comprising the regenerative oxidation device, the mixing device and the fan, wherein,

[0039] The cylindrical shell of the mixing device is internally provided with, from the air inlet end to the air outlet end, a diameter-increasing flow guide cylinder, a first turbulence column, a gas distribution ring tube, a diameter-decreasing flow guide cylinder and a second turbulence column in sequence and coaxially, the small-diameter end of the diameter-increasing flow guide cylinder is connected with the air pipeline, and the large-diameter end is fixed to the inner wall of the cylindrical shell;

[0040] The first turbulence column and the second turbulence column are arranged in the middle part of the cylindrical shell;

[0041] The gas distribution ring tube is connected with the gas pipeline, and the inner side of the gas distribution ring tube is provided with a gas distribution hole;

[0042] The large-diameter end of the diameter-decreasing flow guide cylinder is fixed to the inner wall of the cylindrical shell, and the small-diameter end extends towards the air outlet;

[0043] The air outlet is connected with the air inlet of the regenerative oxidation device through the fan.

[0044] For a large flow of gas, if mechanical stirring devices are used for mixing, a large amount of energy needs to be consumed, and it is difficult to ensure uniform mixing.

[0045] In the mixing device, all the components are fixed components, no energy is consumed, and a large amount of air and a large amount of ultra-low concentration gas can be mixed, and the functions of the components are as follows:

[0046] The diameter-increasing flow guide cylinder is connected with the air pipeline to guide part of the air to the edge of the cylindrical shell of the mixing device, so that the air is quickly distributed on the entire cross section of the cylindrical shell;

[0047] The first turbulence column is arranged downstream of the large-diameter end of the diameter-increasing flow guide cylinder to disturb the air;

[0048] The inner side of the air distribution ring pipe is provided with an air distribution hole, so that the ultra-low concentration gas can be injected into the inside of the cylindrical shell of the mixing device, and the air distribution ring pipe is arranged to reduce the flow cross section of the region. When the turbulent air flow passes through the reduced diameter, the flow rate is accelerated, and the air flowing along the inside of the cylindrical shell is also accelerated to flow inward. The acceleration of the air of different flow directions, the air of different turbulent degrees and the whole air cooperates to accelerate the mixing of the air and the ultra-low concentration gas.

[0049] The reduced diameter flow guide cylinder is arranged downstream of the air distribution ring pipe to accelerate the mixing of the air and the ultra-low concentration gas, and a second spoiler column is used to further disturb and mix the accelerated mixed gas.

[0050] Through the above measures, the uniformity of the mixing of the air and the ultra-low concentration gas can be ensured without applying external energy. The uniformly mixed gas is delivered to the regenerative oxidation device by the fan and is uniformly distributed in the regenerator.

[0051] If the air and the ultra-low concentration gas are not uniformly mixed, the mixed gas entering the regenerator will also cause uneven distribution of the gas and air at different parts of the regenerator, making it difficult for the gas to be fully oxidized and producing harmful gases.

[0052] In some embodiments, the regenerative oxidation device is connected to a waste heat utilization system through a high-temperature heat bypass valve. Heat is provided to the outside.

[0053] In some embodiments, the air outlet of the air chamber is connected to an emptying pipeline.

[0054] In some embodiments, the air chamber is also connected to a purge air pipeline.

[0055] Valves are arranged on the pipeline, including but not limited to lift valves, rotary valves, butterfly valves, etc., to realize the functions of low-concentration gas inlet, outlet, and air chamber purge.

[0056] In some embodiments, the regenerative oxidation device is a horizontal multi-chamber regenerative oxidation device or a rotary multi-chamber regenerative oxidation device.

[0057] If the overall gas concentration of the device is increased to 1.8%-3.0%, the overall thermal efficiency is increased to 90.0%, and the power consumption is reduced by about 12.0%. The problem of efficient utilization of coal mine gas with a concentration of less than 3.0% and more than 5% can be solved, the energy efficiency level is improved, and the extracted gas can also be included in the CCER emission reduction. The safety, high regenerative capacity, high thermal efficiency, high oxidation rate, and high waste heat utilization capacity of the regenerative oxidation of high-flow gas are realized.

[0058] The beneficial effects achieved by one or more embodiments of the above-mentioned application are as follows:

[0059] The direct combustion burner is arranged on the side wall of the combustion chamber, is connected with the gas extraction pipeline, has the functions of preheating at start and increasing output power in normal working condition, uses the normal working combustion chamber as a stable combustion chamber, ensures full and stable gas combustion, can output more heat, and provides enough heat to store heat in the heat storage body, so that the stable heat storage oxidation treatment of the ultra-low concentration gas is ensured.

[0060] The heat storage body is designed as a three-layer structure, the upper heat storage layer is inorganic non-metallic material, the high-temperature section is high-aluminum refractory material, the middle section is mullite material, and the low-temperature section is cordierite material; the middle heat storage layer is metal heat storage material; and the lower heat storage layer is heat pipe heat storage material. The heat storage body can have good heat resistance, quickly recover waste heat in high-temperature flue gas, reduce exhaust air temperature, and quickly preheat incoming air. BRIEF DESCRIPTION OF DRAWINGS

[0061] The drawings accompanying the specification of the present application serve to provide further understanding of the present application, and the illustrative embodiments of the present application and the description thereof serve to explain the present application, and do not constitute an improper limitation on the present application.

[0062] Figure 1 is a main view structural schematic diagram of a five-chamber horizontal heat storage oxidation device in an embodiment of the present application;

[0063] Figure 2 is a structural schematic diagram of a horizontal heat storage oxidation system in an embodiment of the present application;

[0064] Figure 3 is a structural schematic diagram of a rotary heat storage oxidation device in an embodiment of the present application;

[0065] Figure 4 is a structural schematic diagram of a rotary heat storage oxidation system in an embodiment of the present application;

[0066] Figure 5 is a structural schematic diagram of a gas mixing device in an embodiment of the present application;

[0067] Figure 6 is a structural schematic diagram of a gas distribution pipe in an embodiment of the present application;

[0068] Figure 7 is a simulation diagram in a heat storage oxidation process in an embodiment of the present application.

[0069] Among them, 1-air chamber; 2-heat storage chamber; 3-combustion chamber; 4-second upper heat storage layer; 5-second middle heat storage layer; 6-second lower heat storage layer; 7-second secondary burner; 8-second high-temperature heat bypass valve; 9-first upper heat storage layer; 10-first middle heat storage layer; 11-first lower heat storage layer; 12-first secondary burner; 13-first high-temperature heat bypass valve; 14-direct combustion burner; 15-waste heat utilization system; 16-mixing device; 17-fan; 18-air duct; 19-expanded diameter guide tube; 20-first turbulence column; 21-gas duct; 22-reduced diameter guide tube; 23-second turbulence column; 24-exhaust duct; 25-gas distribution ring pipe; 26-gas distribution hole. Detailed Implementation

[0070] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0071] The present invention will be further described below with reference to the embodiments.

[0072] Example 1

[0073] like Figure 1 As shown, a regenerative thermal oxidation device for ultra-low concentration methane in coal mines includes a shell, a regenerator, and a direct-fired burner, wherein...

[0074] The shell is provided with a wind chamber 1, a heat storage chamber 2 and a combustion chamber 3 in sequence from one side to the other. The heat storage chamber 2 is divided into at least two areas. The heat storage body is provided in the heat storage chamber 2. The heat storage body has a layered structure. From the side closer to the combustion chamber 3 to the side closer to the wind chamber, a first upper heat storage layer 9, a first middle heat storage layer 10 and a first lower heat storage layer 11 are provided in sequence.

[0075] The first upper heat storage layer 9 is made of inorganic non-metallic material, with high-alumina refractory material in the high-temperature section, mullite material in the medium-temperature section, and cordierite material in the low-temperature section.

[0076] The first middle heat storage layer 10 is made of metallic heat storage material; the first lower heat storage layer 11 is composed of a heat pipe array.

[0077] The direct-fired burner 14 is installed on the side wall of the combustion chamber 3, and its air inlet end is used to connect to the gas extraction pipeline.

[0078] An air inlet and an air outlet are provided on the side wall of the air chamber 1.

[0079] The heat storage chamber is divided into 5 chambers: heat storage chambers A4, B5, C6, D7, and E8. The five heat storage chambers are configured with two inlets, two outlets, and one cleaning chamber to ensure that the five heat storage chambers can circulate air intake, exhaust, and purge air.

[0080] The thickness ratio of the first upper heat storage layer 9, the first middle heat storage layer 10 and the first lower heat storage layer 11 is 5:3:2.

[0081] In the first upper heat storage layer 9, the thickness ratio of the high-temperature section, the medium-temperature section and the low-temperature section is 4:3:3.

[0082] The heat pipes are arranged in parallel to the first middle heat storage layer 10 to form a heat pipe array, or the evaporation ends of the heat pipes are inserted into or through the middle heat storage layer, and the condensation ends extend out of the first middle heat storage layer 10. The heat pipes are negative pressure heat pipes, normal pressure heat pipes or positive pressure heat pipes.

[0083] The type of the heat pipes is not limited to energy storage heat pipes or heat transfer heat pipes. The heat storage form of the working medium in the energy storage heat pipes includes but is not limited to sensible heat type, phase change type and chemical potential composite type. The heat transfer working medium of the heat transfer heat pipes includes but is not limited to organic type, inorganic type and metal type.

[0084] The side of the first upper heat storage layer 9 close to the combustion chamber 3 is provided with a corundum check brick. This can reduce the radiation of the high-temperature furnace to the heat storage body, and can also increase the stability of the stacking of the heat storage body.

[0085] The type of the first upper heat storage layer 9 includes but is not limited to saddle ring type, sheet type, honeycomb type heat storage body, heat storage ball or heat storage pipe.

[0086] The type of the first middle heat storage layer 10 includes but is not limited to pressed type, wire mesh type, woven type, rod type, block type or spherical type.

[0087] The air chamber 1 of the low-concentration gas heat storage oxidation device is provided with an air inlet pipeline, an air outlet pipeline and a purge pipeline. An air inlet valve is arranged on the air inlet pipeline, an air outlet valve is arranged on the air outlet pipeline, and a purge valve is arranged on the purge pipeline.

[0088] The air make-up combustion mode is adopted to achieve complete combustion of the gas. A plurality of first and second make-up combustors 12 are arranged to avoid the emergence of insufficient combustion air in the gas when the gas concentration is increased to improve the system thermal efficiency. The first and second make-up combustors 12 can be arranged at positions such as the air chamber 1, the heat storage chamber 2 or the combustion chamber 3. The position is determined by simulation experiment. As shown in FIG. 8, the position with high methane concentration is set as the make-up combustion position. Figure 7

[0089] The combustion chamber is provided with first high-temperature heat bypass valves 13 which are used as backups. The purpose is to discharge the additional heat generated by the self-balancing oxidation combustion of the gas through the heat bypass valves for heat recycling.

[0090] A 5.0-15.0% direct combustion combustor 14 for extracted gas is additionally arranged in the central oxidation area of the combustion chamber. The direct combustion combustor 14 has the functions of preheating at start-up and increasing output power under normal working conditions.

[0091] As shown in FIG. 9, the first high-temperature heat bypass valve 13 is arranged in the combustion chamber.​Figure 3 、 Figure 5 and Figure 6 As shown in the drawings, inside the cylindrical shell of the mixing device, from the air inlet end to the air outlet end, there are, in sequence, a diameter-increasing flow guide cylinder 19, a first turbulence column 20, a gas distribution ring tube 25, a diameter-decreasing flow guide cylinder 22, and a second turbulence column 23. The small-diameter end of the diameter-increasing flow guide cylinder 19 is connected to the air pipe 18, and the large-diameter end is fixed to the inner wall of the cylindrical shell.

[0092] The first turbulence column 20 and the second turbulence column 23 are arranged in the middle part of the cylindrical shell.

[0093] The gas distribution ring tube 25 is connected to the gas pipe 21, and the inner side of the gas distribution ring tube 25 is provided with gas distribution holes 26.

[0094] The large-diameter end of the diameter-decreasing flow guide cylinder 22 is fixed to the inner wall of the cylindrical shell, and the small-diameter end extends towards the air outlet.

[0095] The air outlet is connected to the air inlet of the heat storage oxidation device through the fan 17.

[0096] The heat storage oxidation device is connected to the waste heat utilization system 15 through a high-temperature heat bypass valve. It provides heat to the outside.

[0097] The heat storage oxidation method for coal mine ultra-low concentration gas is as follows:

[0098] Step one: first, the direct combustion burner 14 in the central oxidation zone directly burns the extracted gas with a concentration of 5.0-15.0%, preheats the combustion chamber, and after the temperature of the combustion chamber rises to a certain temperature, opens the air outlet valves of the heat storage chambers A4 and B5, the high-temperature flue gas after combustion releases heat through the three layers of heat storage bodies in these two heat storage chambers, and is discharged after the temperature decreases, while the heat storage bodies in the heat storage chambers A4 and B5 absorb heat and store a large amount of heat for heating in the next cycle.

[0099] Step two: perform the first cycle, open the air inlet valves of the heat storage chambers A4 and B5, and 1.5% low-concentration gas enters the heat storage chambers A4 and B5 under the action of the fan, the 1.5% low-concentration gas is heated by the heat storage bodies and then enters the combustion chamber, the direct combustion burner 14 in the central oxidation zone of the combustion chamber directly burns the extracted gas with a concentration of 5.0-15.0% to ensure that the combustion chamber always maintains a high temperature, the 1.5% low-concentration gas is further heated by the high-temperature flue gas after direct combustion and then ignited, the ultra-low concentration gas is oxidized in the combustion chamber to release heat, the high-temperature gas after combustion leaves the combustion chamber, enters the heat storage chambers C6 and D7, releases heat, and is discharged after the temperature decreases, the heat storage chambers C6 and D7 absorb the heat of the high-temperature flue gas to increase the temperature for heating in the next cycle, and the heat storage chamber E8 is purged in this process to reduce the concentration of the residual gas to a safe level.

[0100] Step three: After the above steps are completed, the inlet and outlet valves are switched, and the second cycle is entered. At this time, the regenerator chambers C6 and D7 are in the inlet state, the regenerator transfers heat to the 1.5% low concentration gas, the fresh air is purged through the regenerator chamber A4, and the regenerator chambers B5 and E8 are in the outlet state to complete the energy storage of the regenerator.

[0101] Step four: The third cycle, regenerator chambers B5 and E8 are in the inlet state, regenerator chambers A4 and D7 are in the outlet state, and regenerator chamber C6 is purged.

[0102] Step five, the fourth cycle, regenerator chambers A4 and D7 are in the inlet state, regenerator chambers C6 and E8 are in the outlet state, and regenerator chamber B5 is purged.

[0103] Step six, the fifth cycle, regenerator chambers C6 and E8 are in the inlet state, regenerator chambers A4 and B5 are in the outlet state, and regenerator chamber D7 is purged.

[0104] Step seven, the second cycle of step two is repeated, and the process is continuously alternated. The first and second supplementary burners 12 supplement fresh air to avoid the situation that the gas concentration is too high and the combustion air is insufficient. The direct combustion burner 14 in the central oxidation zone uses gas with a concentration of 5.0-15.0% for direct combustion to ensure that the combustion chamber maintains a high temperature, and the total inlet concentration is increased by 1.8%-3.0%.

[0105] Example 2

[0106] For example, see the rotating regenerative oxidation device shown in Figure 2 The rotating RTO mainly consists of a combustion chamber 3, a regenerator chamber 2 and an air chamber 1. The rotating furnace body is divided into 12 regenerator chambers, which are divided into 5 inlet chambers (preheating zone), 5 outlet chambers (cooling zone), 1 purge chamber and 1 isolation chamber.

[0107] The regenerator is arranged in the regenerator chamber 2, and the regenerator is a layered structure, which is sequentially arranged from the side close to the combustion chamber 3 to the side close to the air chamber as the second upper regenerator layer 4, the second middle regenerator layer 5 and the second lower regenerator layer 6;

[0108] The second upper regenerator layer 4 is an inorganic non-metallic material, the high-temperature section is high-alumina refractory material, the medium-temperature section is mullite material, and the low-temperature section is cordierite material;

[0109] The second middle regenerator layer 5 is a metal regenerator material, and the second lower regenerator layer 6 is composed of heat pipes;

[0110] The thickness ratio of the second upper regenerator layer 4, the second middle regenerator layer 5 and the second lower regenerator layer 6 is 5:3:2.

[0111] The thickness ratio of the high-temperature section, the medium-temperature section and the low-temperature section in the second upper heat storage layer 4 is 4:3:3.

[0112] The heat pipes are arranged in parallel to the second medium-temperature heat storage layer 5 to form a heat pipe array, or the evaporation ends of the heat pipes are inserted into or through the medium-temperature heat storage layer and the condensation ends extend out of the second medium-temperature heat storage layer 5. The heat pipes are negative-pressure heat pipes, normal-pressure heat pipes or positive-pressure heat pipes.

[0113] The type of the heat pipes is not limited to energy storage heat pipes or heat transfer heat pipes. The heat storage form of the working medium in the energy storage heat pipes includes but is not limited to sensible heat type, phase change type and chemical potential composite type heat storage. The heat transfer working medium of the heat transfer heat pipes includes but is not limited to organic type, inorganic type and metal type.

[0114] The side of the second upper heat storage layer 4 close to the combustion chamber 3 is provided with corundum check bricks to reduce the radiation of the high-temperature furnace chamber to the heat storage bodies and to increase the stacking stability of the heat storage bodies.

[0115] The type of the second upper heat storage layer 4 includes but is not limited to saddle ring type, sheet type, honeycomb type heat storage body, heat storage ball or heat storage pipe.

[0116] The type of the second medium-temperature heat storage layer 5 includes but is not limited to pressed type, wire mesh type, woven type, rod type, block type or spherical type.

[0117] The air afterburning method is used to realize complete combustion of gas, and a plurality of second secondary afterburners 7 are arranged to avoid the situation that the increase of gas concentration to improve the system thermal efficiency causes the shortage of combustion air in the gas.

[0118] The combustion chamber is provided with second high-temperature heat bypass valves 8 which are used as backup for each other, and the purpose is to discharge the additional heat generated by the self-balancing oxidation combustion of the gas through the heat bypass valves for heat recycling.

[0119] The central oxidation area of the combustion chamber is additionally provided with 5.0-15.0% of the extracted gas direct combustion burner, and the direct combustion burner has the functions of preheating at start-up and increasing output power under normal working conditions.

[0120] The air and gas mixing device is the same as that in Embodiment 1.

[0121] The heat storage oxidation method for the coal mine ultra-low concentration gas is as follows:

[0122] Step one: first, the direct combustion burner of the central oxidation zone uses the extracted gas with the concentration of 5.0-15.0% to directly combust, the combustion chamber is preheated, after the temperature of the combustion chamber is increased to a certain temperature, the high-temperature gas after combustion preheats the five regenerators under the action of the distribution valve, the high-temperature gas is discharged after the temperature is reduced, and the three layers of regenerators of the five regenerators absorb the heat of the high-temperature gas, store and are used to heat 1.5% of the low-concentration gas in the next cycle, and the fresh air blows the combustion chamber through the blowing chamber.

[0123] Step two: 1.5% of the low-concentration gas enters the regenerator of the first step to be preheated under the action of the distribution valve, the gas is preheated to a certain temperature and enters the top combustion chamber, the 1.5% low-concentration gas enters the combustion chamber and is further heated by the direct combustion high-temperature flue gas, then is ignited, oxidizes and releases heat in the combustion chamber, and is completely oxidized and decomposed. The high-temperature gas after purification leaves the combustion chamber and enters the regenerator, and the heat is transferred to the regenerator of the regenerator, and the gas is cooled and discharged through the gas distributor. The ceramic regenerator of the regenerator absorbs heat and "stores" a large amount of heat (used to heat 1.5% of the low-concentration gas in the next cycle). Thus, the low-concentration gas is continuously alternately oxidized and decomposed in the combustion chamber, the direct combustion burner of the central oxidation zone uses the extracted gas with the concentration of 5.0-15.0% to directly combust, and the combustion chamber is kept at a high temperature, and in this process, the high-temperature heat bypass valve arranged in the combustion chamber discharges the heat generated by the self-balanced oxidation combustion of the gas, and the heat is reused.

[0124] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A regenerative thermal oxidation device for ultra-low concentration methane in coal mines, characterized in that: The application relates to a heat storage and direct combustion device, which comprises a shell, a heat storage body and a direct combustion burner. The shell is internally provided with a wind chamber, a heat storage chamber and a combustion chamber from one side to the other side in sequence, the heat storage chamber is at least divided into two areas, the heat storage body is arranged in the heat storage chamber, the heat storage body is of a layered structure, and an upper heat storage layer, a middle heat storage layer and a lower heat storage layer are sequentially arranged from the side close to the combustion chamber to the side close to the wind chamber. The upper heat storage layer is made of inorganic nonmetallic material, the high-temperature section is made of high-aluminum refractory material, the medium-temperature section is made of mullite material, and the low-temperature section is made of cordierite material. The middle heat storage layer is made of metallic heat storage material, and the lower heat storage layer is made of a heat pipe array. The direct combustion burner is arranged on the side wall of the combustion chamber, and the air inlet end is used for being connected with a gas extraction pipeline. An air inlet and an air outlet are arranged on the side wall of the wind chamber. The thickness ratio of the upper heat storage layer, the middle heat storage layer and the lower heat storage layer is 4-6:2-4:1-3. Preferably, the thickness ratio of the high-temperature section, the medium-temperature section and the low-temperature section in the upper heat storage layer is 3-5:2-4:2-4.

2. The regenerative oxidation device for coal mine ultra-low concentration gas according to claim 1, characterized in that: The heat pipes are arranged in parallel to the middle heat storage layer to form a heat pipe array, or the evaporation end of the heat pipe is inserted into or inserted through the middle heat storage layer, and the condensation end extends out of the middle heat storage layer. The heat pipe is a negative pressure type heat pipe, a normal pressure type heat pipe or a positive pressure type heat pipe.

3. The regenerative oxidation device for coal mine ultra-low concentration gas according to claim 1, characterized in that: The side of the upper heat storage layer close to the combustion chamber is provided with a corundum damper brick.

4. The regenerative oxidation device for coal mine ultra-low concentration gas according to claim 1, characterized in that: The number of the heat storage chambers is an odd number greater than 1, and the side wall of the wind chamber is provided with an air inlet, an air outlet and a purge air inlet.

5. The regenerative oxidation device for coal mine ultra-low concentration gas according to claim 1, characterized in that: A secondary combustion device is arranged in the wind chamber, the heat storage chamber, the combustion chamber or the high-temperature heat bypass pipeline, and is used for supplementing air.

6. A regenerative oxidation system for ultra-low concentration gas in a coal mine, characterized in that: The application further relates to a mixing device and a fan, which are used in combination with the heat storage and direct combustion device. The inner wall of the cylindrical shell is provided with a diameter-expanded flow guide cylinder, a first turbulence column, a gas distribution ring, a diameter-reduced flow guide cylinder and a second turbulence column which are coaxially arranged from the air inlet end to the air outlet end in sequence. The first turbulence column and the second turbulence column are arranged in the middle part of the cylindrical shell. The gas distribution ring is connected with a gas pipeline, and the inner side of the gas distribution ring is provided with a gas distribution hole. The diameter-reduced flow guide cylinder is fixed on the inner wall of the cylindrical shell, and the small-diameter end extends towards the air outlet. The air outlet is connected with the air inlet of the heat storage and direct combustion device through the fan.

7. The coal mine ultra-low concentration gas regenerative oxidation system according to claim 6, characterized in that: The heat storage and direct combustion device is connected with a waste heat utilization system through a high-temperature heat bypass valve.

8. The coal mine ultra-low concentration gas regenerative oxidation system according to claim 6, characterized in that: The wind chamber is further connected with a purge air pipeline.

9. The coal mine ultra-low concentration gas regenerative oxidation system according to claim 6, characterized in that: The heat storage and direct combustion device is a horizontal multi-chamber heat storage and direct combustion device or a rotary multi-chamber heat storage and direct combustion device.

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