A compact coal mine gas multi-mode combustion device and working method thereof

Abstract

The present invention discloses a compact coal mine gas multi-modal combustion device and a working method thereof, comprising an air intake section I, a combustion section II and a heat recovery section III. The porous ceramic flame support layer in the combustion section II forms a mutually nested structure with the combustion chamber, realizing two modes of direct combustion and heat storage submerged combustion. The air intake section I adopts multiple air chambers for independent regulation and cooperates with the combustion section II. When the gas extraction concentration fluctuates, the air intake condition can be automatically adjusted according to different methane concentrations, thereby realizing direct combustion mode, heat storage submerged combustion mode, and a mixed combustion mode in which direct combustion and heat storage submerged combustion are coordinated. The three are automatically switched, thereby adopting different combustion modes for gas mixtures of different concentrations, improving the combustion efficiency of the coal mine gas mixture, and finally realizing the combustion and utilization of coal mine gas with a large flow rate and a wide concentration range in coal mines, thereby achieving the purposes of safe production in coal mines, low-carbon utilization of gas, and energy conservation and emission reduction.

Description

Technical Field

[0001] The invention relates to a compact coal mine gas multi-mode combustion device and a working method thereof, and belongs to the technical and engineering fields related to low-carbon combustion and utilization of coal mine gas, energy conservation and emission reduction, coal mine safety, etc. Background Art

[0002] Coal is the main energy source in my country, and gas is a byproduct of coal, with methane being its main combustible component. The coal industry is one of the main sources of methane emissions in the energy sector. In addition, gas is not only a disaster source for coal mines, but also a strong greenhouse gas and clean energy, and the second largest greenhouse gas after carbon dioxide. In 2021, the IPCC's comprehensive report on climate change pointed out that within a 100-year time frame, the greenhouse effect index GWP100 of methane is 28 times that of carbon dioxide, and its contribution to global warming accounts for about a quarter. Therefore, methane emission reduction in the coal industry is of great significance to promoting the reduction of greenhouse gas emissions.

[0003] Due to the constraints of coal mine gas geological conditions, the concentration of gas extracted from many coal mines is generally low. In some mines, ultra-low concentration gas with a concentration below 8% accounts for more than 70%. The ultra-low methane concentration, large emissions, and fluctuation range across the lower explosion limit have significantly restricted the utilization and emission reduction of ultra-low concentration gas. Statistics show that the utilization rate of coal mine gas in China in 2022 was only about 44.8%.

[0004] Therefore, in response to the problem of utilizing ultra-low concentration gas in coal mines, how to realize the combustion and utilization of coal mine gas with large flow and wide concentration range is a key and major issue that needs to be urgently solved in coal mine safety production, low-carbon utilization of gas, and energy conservation and emission reduction. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a compact coal mine gas multi-modal combustion device and a working method thereof, which can adopt different modes for combustion utilization according to the different concentrations of the coal mine gas mixed gas, thereby realizing the combustion and utilization of coal mine gas with large flow and wide concentration range in coal mines, thereby ensuring safe production in coal mines, low-carbon utilization of gas, and energy conservation and emission reduction.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a compact coal mine gas multi-mode combustion device, comprising an air intake section I, a combustion section II, a heat recovery section III and a control center; the combustion section II is located between the air intake section I and the heat recovery section III, and the three are coaxially connected by a flange;

[0007] The air inlet section I includes an air inlet chamber No. I, an air inlet chamber No. II, an air inlet pipe, and an air or circulating smoke pipe. The air inlet chamber No. II is provided with an air inlet port No. II and an air outlet port No. II, and a second fire-blocking air distribution plate is installed at the air outlet port No. II to prevent the flame from entering the air inlet chamber No. II; the air inlet chamber No. I is provided with an air inlet port No. I and an air outlet port No. I, and the air outlet port No. I is connected to one end of the air inlet pipe, and the other end of the air inlet pipe passes through the air inlet chamber No. II and extends out from the air outlet No. II, and the air inlet pipe near the other end of the air inlet pipe is provided with a first fire-blocking air distribution plate and a flame stabilizer, wherein the first fire-blocking air distribution plate is used to prevent the flame from entering the air inlet chamber No. I, and the flame stabilizer is used for stable combustion of the exhaust gas from the air inlet pipe; one end of the air or circulating smoke pipe is outside the air inlet chamber No. I, and the other end passes through the air inlet chamber No. I and the air inlet pipe in sequence and extends out from the other end of the air inlet pipe; a swirl distributor is installed at the other end of the air or circulating smoke pipe to adjust the flow direction of the exhaust gas;

[0008] The combustion section II is provided with a porous ceramic fire barrier layer, a porous ceramic flame support layer, a combustion chamber and an ignition chamber. The porous ceramic fire barrier layer and the porous ceramic flame support layer are both annular and coaxially arranged; the porous ceramic fire barrier layer is used to prevent the flame from entering the No. II air inlet chamber; the porous ceramic flame support layer is used for heat storage submerged combustion of low-concentration gas; the combustion chamber is on the axis of the porous ceramic fire barrier layer and the porous ceramic flame support layer, and one end of the porous ceramic flame support layer and one end of the combustion chamber are connected to one end of the ignition chamber; the other end of the combustion chamber is connected to the other end of the air inlet pipe, so that the low-concentration gas entering the No. I air inlet chamber The gas enters the combustion chamber through the air inlet pipe for direct combustion; and the other end of the air or circulating flue gas pipe extends into the combustion chamber, so that the gas passing through the air or circulating flue gas pipe enters the combustion chamber; one end of the porous ceramic fire barrier layer is coaxially connected to the gas outlet No. Ⅱ, so as to allow the low-concentration gas entering the air inlet chamber No. Ⅱ to enter the porous ceramic flame support layer; an igniter, a flame monitor and a temperature sensor are arranged in the ignition chamber, the igniter is used to ignite the low-concentration gas entering the combustion section II; the flame monitor is used to monitor the flame condition in the combustion section II; the temperature sensor is used to monitor the temperature condition in the combustion section II;

[0009] The regenerative section III is provided with a porous ceramic heat storage body for storing the heat generated by combustion; the porous ceramic heat storage body is provided with a plurality of drag-reducing flow channels for allowing the post-combustion gas to be discharged from the drag-reducing flow channels;

[0010] Gas concentration monitoring devices are installed at air inlet No. I and air inlet No. II to monitor the gas concentration data at air inlet No. I and air inlet No. II; flow regulating valves are installed at air inlet No. I, air inlet No. II and one end of the air or circulating smoke pipe to control the gas flow entering air inlet chamber No. I, air inlet chamber No. II and the air or circulating smoke pipe; the control center is connected to the igniter, flame monitor, temperature sensor, various gas concentration monitoring devices and various flow regulating valves to control the opening and closing of the igniter, and receive data fed back by the flame monitor, temperature sensor and various gas concentration monitoring devices, and after analysis and processing, adjust the opening of each flow regulating valve.

[0011] Furthermore, the number of the intake pipes is one or more. If there is one, the intake pipe is coaxially arranged with the intake chamber No. Ⅱ and is located at its center; if there are multiple, one of the intake pipes is coaxially arranged with the intake chamber No. Ⅱ and is located at its center, and the remaining intake pipes are evenly arranged around the intake pipe.

[0012] Furthermore, the outer shells of the air intake section I, combustion section II, and heat recovery section III are all metal shells, and the cross-section of each section is circular or square. The inner wall of the metal shell is provided with a fire-resistant layer for fire protection of each section; the outer wall of the metal shell is provided with an insulation layer for heat preservation of each section.

[0013] Furthermore, the first fire-blocking air distribution plate and the second fire-blocking air distribution plate are both porous plate type or capillary type.

[0014] Furthermore, the porous ceramic fire barrier layer, porous ceramic flame support layer and porous ceramic heat storage body are respectively made of a combination of one or more of honeycomb ceramics, foam ceramics or porous refractory materials of different materials (aluminum oxide, cordierite, mullite, etc.) and different pore shapes (square holes, round holes, polygonal holes, etc.); the cross-section of the porous ceramic flame support layer is a uniform cross-section or a stepped arrangement.

[0015] Furthermore, the flame monitor is one or a combination of an infrared spectrum detector, an ultraviolet spectrum detector, an ion probe or a multi-spectrum detector; and the gas concentration monitoring device includes a methane concentration sensor and an oxygen concentration sensor.

[0016] The working method of the above-mentioned compact coal mine gas multi-mode combustion device comprises the following specific steps:

[0017] Step 1: Determine the fire-blocking apertures of the first fire-blocking air distribution plate and the second fire-blocking air distribution plate in the compact coal mine gas multi-mode combustion device, the design apertures of the porous ceramic fire-blocking layer, the design apertures of the porous ceramic flame support layer, and the design apertures of the porous ceramic heat storage body, specifically:

[0018] ① Test and analyze the concentration of various gases in the current coal mine gas mixture:

[0019] ② Experimental determination of the lower limit of ignition concentration of current coal mine gas mixture at 650°C Critical oxygen concentration and flame propagation speed S L ;

[0020] ③ Determine the fire-blocking aperture d0 of the first fire-blocking air distribution plate and the second fire-blocking air distribution plate as:

[0021]

[0022] Where: d0-fire-blocking aperture, m; d cr - critical fire-blocking aperture, m; a- effective area ratio of each fire-blocking air distribution plate (ratio of total cross-sectional area to total pore cross-sectional area); H- thickness of each fire-blocking air distribution plate, m; S L - Flame propagation speed S of gas mixture at 650℃ L , m / s;

[0023] ④Determine the design pore size of the porous ceramic fire barrier layer:

[0024] Determine the design pore size of the porous ceramic flame support layer:

[0025] Determine the design pore size of the porous ceramic thermal storage body:

[0026] Where: d p -The selected pore size of porous ceramics, m; k-The thermal conductivity of gas mixture; S L - Flame propagation speed S of gas mixture at 650℃ L , m / s; ρ-density of gas mixture, kg / m 3 ; C p -Specific heat of gas mixture, kJ / m 3 ℃;

[0027] Step 2: Assemble the compact coal mine gas multi-mode combustion device, and connect its No. I and No. II air inlets to the gas extraction pipeline of the current coal mine; connect one end of the air or circulating flue gas pipe to the air compressor or flue gas circulating pump to complete the layout;

[0028] Step 3: The gas extraction pipeline of the current coal mine continuously transports the extracted gas mixture to the No. I and No. II gas inlets. At this time, the gas concentration monitoring devices of the No. I and No. II gas inlets monitor the various gases in the gas mixture and feed back to the control center. The control center controls each flow regulating valve in real time according to the monitoring results, thereby realizing the combustion and utilization of different gas mixtures. Specifically:

[0029] A. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I and No. II inlets are both greater than or equal to 8%, the control center controls the flow control valve of the No. I inlet to the maximum opening, and closes the flow control valve of the No. II inlet at the same time. At this time, the gas mixture enters the combustion chamber from the No. I inlet through the No. I inlet chamber and the inlet pipe in sequence, and then the control center controls the igniter to ignite to realize the direct combustion of coal mine gas; at the same time, the temperature sensor and the flame monitor monitor the temperature data and flame data in the combustion chamber in real time and feed them back to the control center;

[0030] B. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I and No. II inlets are both greater than or equal to 5% but less than 8%, the control center controls the opening degree of the flow control valve of the No. I inlet to not exceed 50% of the rated working condition, and at the same time opens the flow control valve of the No. II inlet to the maximum opening degree. At this time, a part of the gas mixture passes through the No. I inlet chamber and the inlet pipe from the No. I inlet in turn into the combustion chamber, and the other part passes through the No. II inlet chamber in turn into the porous ceramic flame support layer from the No. II inlet in turn, realizing the mixed combustion of coal mine gas direct combustion and heat storage submerged combustion. At the same time, the temperature sensor and the flame monitor monitor the temperature data and flame data in the combustion chamber in real time and feed them back to the control center;

[0031] C. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I and No. II inlets are both greater than or equal to 3% but less than 5%, the control center controls the flow control valve of the No. II inlet to the maximum opening, and closes the flow control valve of the No. I inlet at the same time. At this time, the gas mixture passes through the No. II inlet chamber from the No. II inlet in turn and enters the porous ceramic flame support layer to achieve the heat storage submerged combustion of coal mine gas; at the same time, the temperature sensor and the flame monitor monitor the temperature data and flame data in the combustion chamber in real time and feed them back to the control center;

[0032] D. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I and No. II air inlets are both less than 3%, the control center controls the flow control valves of the No. I and No. II air inlets to close, and opens the flow control valves of the air or circulating flue gas pipes, so that the air or circulating flue gas passes through the air or circulating flue gas pipes into the combustion chamber and ignition chamber for purging;

[0033] E. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I and No. II air inlets are both greater than or equal to 8%, and the oxygen concentrations monitored are both less than 12%, the control center controls the flow control valve of the No. I air inlet to the maximum opening, closes the flow control valve of the No. II air inlet, and opens the flow control valve of the air or circulating flue gas pipe. At this time, the gas mixture enters the combustion chamber from the No. I air inlet through the No. I air inlet chamber and the air inlet pipe in sequence, and at the same time, the air is transported to the combustion chamber through the air or circulating flue gas pipe to increase the oxygen concentration in the combustion chamber, thereby achieving complete combustion of coal mine gas;

[0034] F. During the gas combustion and utilization process under the above-mentioned various situations, when the temperature value monitored by the temperature sensor exceeds 1200°C, the control center controls the flow regulating valve of the air inlet No. I to reduce its opening degree and closes the flow regulating valve of the air inlet No. II. At this time, the flow of the gas mixture entering the combustion chamber is reduced. At the same time, the flow regulating valve of the air or circulating flue gas pipe is opened and its opening degree is controlled, so that the air or circulating flue gas enters the combustion chamber to dilute the methane concentration in the gas mixture, thereby achieving safe combustion of coal mine gas.

[0035] Compared with the prior art, the present invention adopts a combination of air intake section I, combustion section II, heat recovery section III and control center, which has the following advantages:

[0036] 1. The present invention determines the structure and parameters of the porous ceramic fire barrier layer, the porous ceramic flame support layer, and the porous ceramic heat storage layer according to the actual data of the coal mine gas mixture, and then forms a compact coal mine gas multi-modal combustion device suitable for current coal mines, thereby realizing controllable, safe and stable combustion of coal mine gas.

[0037] 2. The porous ceramic flame support layer in the combustion section II of the present invention forms a heat storage combustion chamber for coal mine gas, and forms a mutually nested structure with the direct combustion chamber of coal mine gas, thereby strengthening the turbulent flow of gas and heat reflux, and realizing that the combustion section II has both direct combustion and heat storage submerged combustion modes, providing support for the subsequent selection of different combustion modes for different concentrations of gas.

[0038] 3. The air intake section I of the present invention adopts multi-chamber independent air intake regulation and cooperates with the combustion section II. It can realize independent regulation of different combustion chambers and independent control of multiple combustion modes according to the coal mine gas concentration range. In this way, during the fluctuation of underground gas extraction concentration, the present invention can automatically adjust the air intake according to different methane concentrations, thereby realizing direct combustion mode, heat storage submerged combustion mode, and mixed combustion mode in which direct gas combustion and heat storage submerged combustion are coordinated. The three are automatically switched, so that different combustion methods are adopted for gas mixtures of different concentrations, thereby improving the combustion efficiency of coal mine gas mixtures.

[0039] 4. The independently arranged and individually adjustable air or circulating flue gas pipe in the air intake section I of the present invention monitors the oxygen concentration in the gas mixture on the basis of the above-mentioned different combustion modes, adjusts the combustion efficiency by adding air to ensure efficient combustion, and can also control the combustion temperature by circulating flue gas to avoid overheating and reduce the generation of nitrogen oxides.

[0040] 5. The control center of the present invention can receive the temperature value monitored by the temperature sensor in real time. If the monitored temperature value exceeds the safety threshold, it can timely reduce the flow rate of the gas mixture entering the combustion section II, and dilute the methane concentration in the combustion section II by supplementing air or circulating flue gas, thereby realizing the safe combustion of coal mine gas. Through multiple mode switching and regulation of safe combustion, it can eventually realize the combustion and utilization of coal mine gas with large flow and wide concentration range, thereby achieving the purpose of safe production in coal mines, low-carbon utilization of gas, and energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the internal structure of embodiment 1 of the present invention

[0042] Figure 2 yes Figure 1 AA section and BB section of

[0043] Figure 3 Schematic diagram of the internal structure of Embodiment 2 of the present invention

[0044] Figure 4 yes Figure 3 AA section and BB section of

[0045] Figure 5 Schematic diagram of the internal structure of Embodiment 3 of the present invention

[0046] Figure 6 yes Figure 5 AA section view and BB section view.

[0047] In the figure: 1-metal shell, 2-air inlet No. I, 3-air inlet No. II, 4-flame stabilizer, 5-swirl distributor, 6-igniter, 7-flame monitor, 8-temperature sensor, 9-porous ceramic heat storage body, 10-drag reduction flow channel, 11-ignition chamber, 12-combustion chamber, 13-porous ceramic flame support layer, 14-porous ceramic fire barrier layer, 15-second fire barrier air distribution plate, 16-first fire barrier air distribution plate, 17-air inlet chamber No. II, 18-metal plate, 19-air inlet chamber No. I, 20-inlet pipe, 21-air or circulating flue gas pipe. DETAILED DESCRIPTION

[0048] The present invention will be further described below.

[0049] Embodiment 1:

[0050] like Figure 1 As shown, a compact coal mine gas multi-mode combustion device includes an air intake section I, a combustion section II, a heat recovery section III and a control center; the combustion section II is located between the air intake section I and the heat recovery section III, and the three are coaxially connected through a flange;

[0051] The air inlet section I comprises an air inlet chamber No. I 19, an air inlet chamber No. II 17, an air inlet pipe 20, and an air or circulating smoke pipe 21. The air inlet chamber No. II 17 is provided with an air inlet No. II and an air outlet No. II, and a second fire-blocking air distribution plate 15 is installed at the air outlet No. II to prevent the flame from entering the air inlet chamber No. II 17; the air inlet chamber No. I 19 is provided with an air inlet No. I 2 and an air outlet No. I 3, and the air outlet No. I 2 is connected to one end of the air inlet pipe 20, and the other end of the air inlet pipe 20 passes through the air inlet chamber No. II 17 and extends from the air outlet No. II, and the air inlet pipe 20 near the other end of the air inlet pipe is provided with a first fire-blocking air distribution plate 16 and a flame stabilizer 4, wherein the first fire-blocking air distribution plate 16 is used to prevent the flame from entering the air inlet chamber No. I 19, and the flame stabilizer 4 is used for the stable combustion of the gas discharged from the air inlet pipe 20; Figure 2 As shown, there is one air inlet pipe 20, which is coaxially arranged with the No. II air inlet chamber 17 and located at the center thereof; one end of the air or circulating smoke pipe 21 is located outside the No. I air inlet chamber 19, and the other end passes through the No. I air inlet chamber 19 and the air inlet pipe 20 in sequence and extends out from the other end of the air inlet pipe 19; a swirl distributor 5 is installed at the other end of the air or circulating smoke pipe 21 for adjusting the flow direction of the exhaust gas; the first fire-blocking air distribution plate 16 and the second fire-blocking air distribution plate 15 are both porous plate type or capillary type;

[0052] The combustion section II is provided with a porous ceramic fire barrier layer 14, a porous ceramic flame support layer 13, a combustion chamber 12 and an ignition chamber 11. The porous ceramic fire barrier layer 14 and the porous ceramic flame support layer 13 are both annular and coaxially arranged; wherein the porous ceramic fire barrier layer 14 is used to prevent the flame from entering the air inlet chamber II 17; the porous ceramic flame support layer 13 is used for heat storage submerged combustion of low-concentration gas; the cross-section of the porous ceramic flame support layer 13 is arranged in an equal cross-section; the combustion chamber 12 is on the axis of the porous ceramic fire barrier layer 14 and the porous ceramic flame support layer 13, and one end of the porous ceramic flame support layer 13 and one end of the combustion chamber 12 are connected to one end of the ignition chamber 11; the other end of the combustion chamber 12 is connected to the other end of the air inlet pipe 20 The two sides of the combustion chamber 11 are connected so that the low-concentration gas entering the No. I air inlet chamber 19 enters the combustion chamber 11 through the air inlet pipe 20 for direct combustion; and the other end of the air or circulating flue gas pipe 21 extends into the combustion chamber 11, so that the gas passing through the air or circulating flue gas pipe 21 enters the combustion chamber 12; one end of the porous ceramic fire barrier layer 14 is coaxially connected with the No. II gas outlet, so as to allow the low-concentration gas entering the No. II air inlet chamber 17 to enter the porous ceramic flame support layer 13; the igniter 6, the flame monitor 7 and the temperature sensor 8 are arranged in the ignition chamber 11, the igniter 6 is used to ignite the low-concentration gas entering the combustion section II; the flame monitor 7 is used to monitor the flame condition in the combustion section II; the temperature sensor 8 is used to monitor the temperature condition in the combustion section II;

[0053] The regenerative section III is provided with a porous ceramic heat storage body 9 for storing the heat generated by combustion; the porous ceramic heat storage body 9 is provided with a plurality of drag reduction flow channels 10 for allowing the post-combustion gas to be quickly discharged from the drag reduction flow channels 10;

[0054] Gas concentration monitoring devices are installed at air inlet No. 1 2 and air inlet No. 2 3, which include methane concentration sensors and oxygen concentration sensors for monitoring gas concentration data at air inlet No. 1 2 and air inlet No. 2 3; flow regulating valves are installed at air inlet No. 1 2, air inlet No. 2 3 and one end of the air or circulating flue gas pipe 20 for controlling the gas flow entering air inlet chamber No. 19, air inlet chamber No. 2 17 and air or circulating flue gas pipe 21; the control center is connected to the igniter 6, flame monitor 7, temperature sensor 8, various gas concentration monitoring devices and various flow regulating valves for controlling the opening and closing of the igniter 6, and receiving data fed back by the flame monitor 7, temperature sensor 8 and various gas concentration monitoring devices, and adjusting the opening of each flow regulating valve after analysis and processing.

[0055] As an improvement of the present invention, the outer shells of the air intake section I, combustion section II, and heat recovery section III are all metal shells 1, and the cross-section of each section is circular or square. The inner wall of the metal shell 1 is provided with a fire-resistant layer for fire protection of each section; the outer wall of the metal shell 1 is provided with an insulation layer for insulation of each section.

[0056] As another improvement of the present invention, the porous ceramic fire barrier layer 14, the porous ceramic flame support layer 13 and the porous ceramic heat storage body 9 are respectively made of one or more combinations of honeycomb ceramics, foam ceramics or porous refractory materials of different materials (aluminum oxide, cordierite, mullite, etc.) and different pore shapes (square holes, round holes, polygonal holes, etc.); the flame monitor 7 is one or more combinations of infrared spectrum detectors, ultraviolet spectrum detectors, ion probes or multi-spectrum detectors.

[0057] Embodiment 2:

[0058] like Figure 3 and 4 As shown, the compact coal mine gas multi-mode combustion device is different from Example 1 only in that the cross section of the porous ceramic flame support layer 13 is arranged in steps.

[0059] Embodiment 3:

[0060] like Figure 5 and 6 As shown, the difference between the compact coal mine gas multi-mode combustion device and Example 1 is that there are five air intake pipes 20, one of which is coaxially arranged with the No. Ⅱ air intake chamber 17 and is located at the center thereof, and the remaining four air intake pipes are evenly arranged around the air intake pipe.

[0061] The working methods of the above embodiments 1 to 3 are the same, and the specific steps are:

[0062] Step 1: Determine the fire-blocking apertures of the first fire-blocking air distribution plate 16 and the second fire-blocking air distribution plate 15 in the compact coal mine gas multi-modal combustion device, the design aperture of the porous ceramic fire-blocking layer 14, the design aperture of the porous ceramic flame support layer 13, and the design aperture of the porous ceramic heat storage body 9, specifically:

[0063] ① Test and analyze the concentration of various gases in the current coal mine gas mixture: C CH4 , C O2 , C CO2 , C N2 ;

[0064] ② Experimental determination of the lower limit of ignition concentration of current coal mine gas mixture at 650°C Critical oxygen concentration and flame propagation speed S L ;

[0065] ③ Determine the fire-blocking aperture d0 of the first fire-blocking air distribution plate 16 and the second fire-blocking air distribution plate 15 as:

[0066]

[0067] Where: d0-fire-blocking aperture, m; d cr - critical fire-blocking aperture, m; a- effective area ratio of each fire-blocking air distribution plate (ratio of total cross-sectional area to total pore cross-sectional area); H- thickness of each fire-blocking air distribution plate, m; S L - Flame propagation speed S of gas mixture at 650℃ L , m / s;

[0068] ④ Determine the design aperture of the porous ceramic fire barrier layer 14:

[0069] Determine the design pore size of the porous ceramic flame support layer 13:

[0070] Determine the design pore size of the porous ceramic heat storage body 9:

[0071] Where: d p -The selected pore size of porous ceramics, m; k-The thermal conductivity of gas mixture; S L - Flame propagation speed S of gas mixture at 650℃ L , m / s; ρ-density of gas mixture, kg / m 3 ; C p -Specific heat of gas mixture, kJ / m 3 ℃;

[0072] Step 2: Assemble the compact coal mine gas multi-mode combustion device, and connect its No. I air inlet 2 and No. II air inlet 3 to the gas extraction pipeline of the current coal mine; connect one end of the air or circulating flue gas pipe 20 to the air compressor or flue gas circulating pump to complete the layout;

[0073] Step 3: The gas extraction pipeline of the current coal mine continuously transports the extracted gas mixture to the No. 1 gas inlet 2 and the No. 2 gas inlet 3. At this time, the gas concentration monitoring devices of the No. 1 gas inlet 2 and the No. 2 gas inlet 3 monitor the various gases in the gas mixture and feed back to the control center. The control center controls each flow regulating valve in real time according to the monitoring results, thereby realizing the combustion and utilization of different gas mixtures, specifically:

[0074] A. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I air inlet 2 and the No. II air inlet 3 are both greater than or equal to 8%, the control center controls the flow regulating valve of the No. I air inlet 2 to be at the maximum opening, and closes the flow regulating valve of the No. II air inlet 3 at the same time. At this time, the gas mixture enters the combustion chamber 12 from the No. I air inlet 2 through the No. I air inlet chamber 19 and the air inlet pipe 20 in sequence, and then the control center controls the igniter 6 to ignite to realize the direct combustion of coal mine gas; at the same time, the temperature sensor 8 and the flame monitor 7 monitor the temperature data and flame data in the combustion chamber 12 in real time and feed them back to the control center;

[0075] B. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I air inlet 2 and the No. II air inlet 3 are both greater than or equal to 5% but less than 8%, the control center controls the opening degree of the flow control valve of the No. I air inlet 2 to be no more than 50% of the rated working condition, and at the same time opens the flow control valve of the No. II air inlet 3 to the maximum opening degree. At this time, a part of the gas mixture passes through the No. I air inlet chamber 19 and the air inlet pipe 20 from the No. I air inlet 2 in sequence and enters the combustion chamber 12, and the other part passes through the No. II air inlet chamber 17 from the No. II air inlet 3 in sequence and enters the porous ceramic flame support layer 13, realizing the mixed combustion of direct combustion of coal mine gas and heat storage submerged combustion. At the same time, the temperature sensor 8 and the flame monitor 7 monitor the temperature data and flame data in the combustion chamber 12 in real time and feed them back to the control center;

[0076] C. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I air inlet 2 and the No. II air inlet 3 are both greater than or equal to 3% but less than 5%, the control center controls the flow regulating valve of the No. II air inlet to be at the maximum opening, and closes the flow regulating valve of the No. I air inlet 2 at the same time. At this time, the gas mixture passes through the No. II air inlet chamber 17 from the No. II air inlet 3 and enters the porous ceramic flame support layer 13 in sequence, realizing the heat storage submerged combustion of coal mine gas; at the same time, the temperature sensor 8 and the flame monitor 7 monitor the temperature data and flame data in the combustion chamber in real time and feed them back to the control center;

[0077] D. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I air inlet 2 and the No. II air inlet 3 are both less than 3%, the control center controls the flow control valves of the No. I air inlet 2 and the No. II air inlet 3 to close, and opens the flow control valve of the air or circulating flue gas pipe 20, so that the air or circulating flue gas passes through the air or circulating flue gas pipe 20 into the combustion chamber 12 and the ignition chamber for purging;

[0078] E. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I air inlet 2 and the No. II air inlet 3 are both greater than or equal to 8%, and the oxygen concentrations monitored are both less than 12%, the control center controls the flow regulating valve of the No. I air inlet 2 to be at the maximum opening, closes the flow regulating valve of the No. II air inlet 3, and opens the flow regulating valve of the air or circulating flue gas pipe 20. At this time, the gas mixture enters the combustion chamber 12 from the No. I air inlet 2 through the No. I air inlet chamber 19 and the air inlet pipe 20 in sequence, and at the same time, the air is transported to the combustion chamber 12 through the air or circulating flue gas pipe 20 to increase the oxygen concentration in the combustion chamber 12, thereby achieving complete combustion of coal mine gas;

[0079] F. During the gas combustion and utilization process under the above-mentioned various situations, when the temperature value monitored by the temperature sensor 8 exceeds 1200°C, the control center controls the flow regulating valve of the air inlet 2 No. I to reduce its opening degree and closes the flow regulating valve of the air inlet 3 No. II. At this time, the flow of the gas mixture entering the combustion chamber 12 is reduced. At the same time, the flow regulating valve of the air or circulating flue gas pipe 20 is opened and its opening degree is controlled, so that the air or circulating flue gas enters the combustion chamber 12 to dilute the methane concentration in the gas mixture, thereby realizing the safe combustion of coal mine gas.

[0080] In addition, the above embodiment is not only applicable to the combustion of coal mine gas, but also applicable to the combustion of other types of combustible gases such as blast furnace gas, marsh gas, biomass gas and other combustible gases, and the parameters can be adjusted as needed.

[0081] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A compact coal mine gas multi-mode combustion device, characterized in that: It includes air intake section I, combustion section II, heat recovery section III and control center; combustion section II is located between air intake section I and heat recovery section III, and the three are coaxially connected by flanges; The air inlet section I includes an air inlet chamber No. I, an air inlet chamber No. II, an air inlet pipe, and an air or circulating smoke pipe. The air inlet chamber No. II is provided with an air inlet port No. II and an air outlet port No. II, and a second fire-blocking air distribution plate is installed at the air outlet port No. II to prevent the flame from entering the air inlet chamber No. II; the air inlet chamber No. I is provided with an air inlet port No. I and an air outlet port No. I, and the air outlet port No. I is connected to one end of the air inlet pipe, and the other end of the air inlet pipe passes through the air inlet chamber No. II and extends out from the air outlet No. II, and the air inlet pipe near the other end of the air inlet pipe is provided with a first fire-blocking air distribution plate and a flame stabilizer, wherein the first fire-blocking air distribution plate is used to prevent the flame from entering the air inlet chamber No. I, and the flame stabilizer is used for stable combustion of the exhaust gas from the air inlet pipe; one end of the air or circulating smoke pipe is outside the air inlet chamber No. I, and the other end passes through the air inlet chamber No. I and the air inlet pipe in sequence and extends out from the other end of the air inlet pipe; a swirl distributor is installed at the other end of the air or circulating smoke pipe to adjust the flow direction of the exhaust gas; The combustion section II is provided with a porous ceramic fire barrier layer, a porous ceramic flame support layer, a combustion chamber and an ignition chamber. The porous ceramic fire barrier layer and the porous ceramic flame support layer are both annular and coaxially arranged; the porous ceramic fire barrier layer is used to prevent the flame from entering the No. II air inlet chamber; the porous ceramic flame support layer is used for heat storage submerged combustion of low-concentration gas; the combustion chamber is on the axis of the porous ceramic fire barrier layer and the porous ceramic flame support layer, and one end of the porous ceramic flame support layer and one end of the combustion chamber are connected to one end of the ignition chamber; the other end of the combustion chamber is connected to the other end of the air inlet pipe, so that the low-concentration gas entering the No. I air inlet chamber The low-concentration gas enters the combustion chamber through the air inlet pipe for direct combustion; and the other end of the air or circulating flue gas pipe extends into the combustion chamber, so that the gas passing through the air or circulating flue gas pipe enters the combustion chamber; one end of the porous ceramic fire barrier layer is coaxially connected to the No. Ⅱ gas outlet, so as to allow the low-concentration gas entering the No. Ⅱ air inlet chamber to enter the porous ceramic flame support layer; an igniter, a flame monitor and a temperature sensor are arranged in the ignition chamber, and the igniter is used to ignite the low-concentration gas entering the combustion section II; the flame monitor is used to monitor the flame condition in the combustion section II; the temperature sensor is used to monitor the temperature condition in the combustion section II; The regenerative section III is provided with a porous ceramic heat storage body for storing the heat generated by combustion; the porous ceramic heat storage body is provided with a plurality of drag-reducing flow channels for allowing the post-combustion gas to be discharged from the drag-reducing flow channels; Gas concentration monitoring devices are installed at air inlet No. I and air inlet No. II to monitor the gas concentration data at air inlet No. I and air inlet No. II; flow regulating valves are installed at air inlet No. I, air inlet No. II and one end of the air or circulating smoke pipe to control the gas flow entering air inlet chamber No. I, air inlet chamber No. II and the air or circulating smoke pipe; the control center is connected to the igniter, flame monitor, temperature sensor, various gas concentration monitoring devices and various flow regulating valves to control the opening and closing of the igniter, and receive data fed back by the flame monitor, temperature sensor and various gas concentration monitoring devices, and after analysis and processing, adjust the opening of each flow regulating valve.

2. According to claim 1, the compact coal mine gas multi-mode combustion device is characterized in that: The number of the intake pipes is one or more. If there is one, the intake pipe is coaxially arranged with the intake chamber No. Ⅱ and is located at its center; if there are multiple, one of the intake pipes is coaxially arranged with the intake chamber No. Ⅱ and is located at its center, and the remaining intake pipes are evenly arranged around the intake pipe.

3. The compact coal mine gas multi-mode combustion device according to claim 1 is characterized in that: The outer shells of the air intake section I, combustion section II and heat recovery section III are all metal shells, and the cross-section of each section is circular or square. The inner wall of the metal shell is provided with a fire-resistant layer for fire protection of each section; the outer wall of the metal shell is provided with an insulation layer for heat preservation of each section.

4. The compact coal mine gas multi-mode combustion device according to claim 1 is characterized in that: The first fire-blocking air distribution plate and the second fire-blocking air distribution plate are both porous plate type or capillary type.

5. The compact coal mine gas multi-mode combustion device according to claim 1 is characterized in that: The porous ceramic fire barrier layer, porous ceramic flame support layer and porous ceramic heat storage body are respectively made of a combination of one or more of honeycomb ceramics, foam ceramics or porous refractory materials with different materials and pore shapes; the cross section of the porous ceramic flame support layer is a uniform cross section or a stepped arrangement.

6. The compact coal mine gas multi-mode combustion device according to claim 1 is characterized in that: The flame monitor is one or a combination of an infrared spectrum detector, an ultraviolet spectrum detector, an ion probe or a multi-spectrum detector; the gas concentration monitoring device includes a methane concentration sensor and an oxygen concentration sensor.

7. A method for operating the compact coal mine gas multi-mode combustion device according to any one of claims 1 to 6, characterized in that: The specific steps are: Step 1: Determine the fire-blocking apertures of the first fire-blocking air distribution plate and the second fire-blocking air distribution plate in the compact coal mine gas multi-mode combustion device, the design apertures of the porous ceramic fire-blocking layer, the design apertures of the porous ceramic flame support layer, and the design apertures of the porous ceramic heat storage body, specifically: ① Test and analyze the concentration of various gases in the current coal mine gas mixture: C CH4 , C O2 , C CO2 , C N2 ; ② Experimental determination of the lower ignition concentration limit LFL of the current coal mine gas mixture at 650°C CH4 , critical oxygen concentration C O2,cr and flame propagation speed S L ; ③ Determine the fire-blocking aperture d0 of the first fire-blocking air distribution plate and the second fire-blocking air distribution plate as: Where: d0-fire-blocking aperture, m; d cr - critical fire-blocking aperture, m; a-effective area ratio of each fire-blocking air distribution plate; H-thickness of each fire-blocking air distribution plate, m; S L - Flame propagation speed S of gas mixture at 650℃ L , m / s; ④Determine the design pore size of the porous ceramic fire barrier layer: Determine the design pore size of the porous ceramic flame support layer: Determine the design pore size of the porous ceramic thermal storage body: Where: d p -The selected pore size of porous ceramics, m; k-The thermal conductivity of gas mixture; S L - Flame propagation speed S of gas mixture at 650℃ L , m / s; ρ-density of gas mixture, kg / m 3 ; C p -Specific heat of gas mixture, kJ / m 3 ℃; Step 2: Assemble the compact coal mine gas multi-mode combustion device, and connect its No. I and No. II air inlets to the gas extraction pipeline of the current coal mine; connect one end of the air or circulating flue gas pipe to the air compressor or flue gas circulating pump to complete the layout; Step 3: The gas extraction pipeline of the current coal mine continuously transports the extracted gas mixture to the No. I and No. II gas inlets. At this time, the gas concentration monitoring devices of the No. I and No. II gas inlets monitor the various gases in the gas mixture and feed back to the control center. The control center controls each flow regulating valve in real time according to the monitoring results, thereby realizing the combustion and utilization of different gas mixtures. Specifically: A. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I and No. II inlets are both greater than or equal to 8%, the control center controls the flow control valve of the No. I inlet to the maximum opening, and closes the flow control valve of the No. II inlet at the same time. At this time, the gas mixture enters the combustion chamber from the No. I inlet through the No. I inlet chamber and the inlet pipe in sequence, and then the control center controls the igniter to ignite to realize the direct combustion of coal mine gas; at the same time, the temperature sensor and the flame monitor monitor the temperature data and flame data in the combustion chamber in real time and feed them back to the control center; B. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I and No. II inlets are both greater than or equal to 5% but less than 8%, the control center controls the opening degree of the flow control valve of the No. I inlet to not exceed 50% of the rated working condition, and at the same time opens the flow control valve of the No. II inlet to the maximum opening degree. At this time, a part of the gas mixture passes through the No. I inlet chamber and the inlet pipe from the No. I inlet in turn into the combustion chamber, and the other part passes through the No. II inlet chamber in turn into the porous ceramic flame support layer from the No. II inlet in turn, realizing the mixed combustion of coal mine gas direct combustion and heat storage submerged combustion. At the same time, the temperature sensor and the flame monitor monitor the temperature data and flame data in the combustion chamber in real time and feed them back to the control center; C. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I and No. II inlets are both greater than or equal to 3% but less than 5%, the control center controls the flow control valve of the No. II inlet to the maximum opening, and closes the flow control valve of the No. I inlet at the same time. At this time, the gas mixture passes through the No. II inlet chamber from the No. II inlet in turn and enters the porous ceramic flame support layer to achieve the heat storage submerged combustion of coal mine gas; at the same time, the temperature sensor and the flame monitor monitor the temperature data and flame data in the combustion chamber in real time and feed them back to the control center; D. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I and No. II air inlets are both less than 3%, the control center controls the flow control valves of the No. I and No. II air inlets to close, and opens the flow control valves of the air or circulating flue gas pipes, so that the air or circulating flue gas passes through the air or circulating flue gas pipes into the combustion chamber and ignition chamber for purging; E. When the methane concentrations monitored by the gas concentration monitoring devices of the No. I and No. II air inlets are both greater than or equal to 8%, and the oxygen concentrations monitored are both less than 12%, the control center controls the flow control valve of the No. I air inlet to the maximum opening, closes the flow control valve of the No. II air inlet, and opens the flow control valve of the air or circulating flue gas pipe. At this time, the gas mixture enters the combustion chamber from the No. I air inlet through the No. I air inlet chamber and the air inlet pipe in sequence, and at the same time, the air is transported to the combustion chamber through the air or circulating flue gas pipe to increase the oxygen concentration in the combustion chamber, thereby achieving complete combustion of coal mine gas; F. During the gas combustion and utilization process under the above-mentioned various situations, when the temperature value monitored by the temperature sensor exceeds 1200°C, the control center controls the flow regulating valve of the air inlet No. I to reduce its opening degree and closes the flow regulating valve of the air inlet No. II. At this time, the flow of the gas mixture entering the combustion chamber is reduced. At the same time, the flow regulating valve of the air or circulating flue gas pipe is opened and its opening degree is controlled, so that the air or circulating flue gas enters the combustion chamber to dilute the methane concentration in the gas mixture, thereby achieving safe combustion of coal mine gas.

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