Ultra-low concentration gas dual oxidation heating system

Abstract

The present invention belongs to the technical field of ultra-low concentration gas processing and utilization, and particularly relates to an ultra-low concentration gas dual oxidation heating system. The system solves the reliability problem of gas mixing and the problem of gas pipeline freezing in winter, and comprises a mixer connected to the gas extraction pipeline, the mixer is connected to the blower through an air preheater, the mixer is connected to an ultra-low concentration gas dual oxidation device, an inlet switching valve is arranged at the inlet of the ultra-low concentration gas dual oxidation device, an outlet switching valve is arranged at the outlet of the ultra-low concentration gas dual oxidation device, the outlet of the ultra-low concentration gas dual oxidation device is connected to chimney I through a main induced draft fan, the ultra-low concentration gas dual oxidation device is also connected to a waste heat boiler through a pipeline, the waste heat boiler is respectively connected to the boiler induced draft fan and the air preheater, the boiler induced draft fan is connected to chimney II, an antifreeze flue gas valve is arranged between the waste heat boiler and the air preheater, a smoke exhaust regulating valve is arranged between the waste heat boiler and the boiler induced draft fan, and the air preheater is connected to the boiler induced draft fan.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-low concentration gas processing and utilization, and in particular relates to an ultra-low concentration gas double oxidation heating system. Background Art

[0002] Ultra-low concentration gas refers to coal mine gas with a methane concentration of 0.3% to 3%. Gas in this concentration range is far below the explosion limit and cannot burn under natural conditions. The ultra-low concentration gas dual oxidation system uses heat storage, catalysis and other technologies to oxidize and decompose coal mine gas with a concentration of 0.3% to 3% into carbon dioxide and water, and recovers heat to ensure a complete set of equipment systems with safe operation.

[0003] The mixing device of the prior art requires a large mixing space, a long mixing distance, and poor mixing uniformity. The ultra-low concentration gas dual oxidation system of the present invention adopts a multi-stage mixer, and the low concentration gas is quickly mixed with air in the mixer to form an ultra-low concentration gas with a gas concentration of less than 3%, which can ensure the safe operation of the oxidation system and greatly improve the safety of the oxidation system.

[0004] The prior art does not have front-end pipeline heating measures, which may lead to safety hazards such as valve failure and pipeline blockage caused by pipeline freezing in winter, which is very likely to cause safety accidents. If electric heating, steam heating and other methods are used, additional heating equipment investment and heating energy consumption are required. The ultra-low concentration gas oxidation system of the present invention uses the heat of exhaust flue gas to solve the problem of gas pipeline freezing in winter, without the need for additional heat sources, almost without increasing operating costs, and at the same time can improve heat utilization efficiency. Summary of the invention

[0005] In order to solve the reliability problem of gas mixing and the freezing problem of gas pipelines in winter, the present invention provides an ultra-low concentration gas double oxidation heating system.

[0006] The present invention adopts the following technical scheme: an ultra-low concentration gas dual oxidation heating system, including a mixer connected to a gas extraction pipeline, the mixer is connected to a blower through an air preheater, the mixer is connected to an ultra-low concentration gas dual oxidation device, an inlet switching valve is arranged at the inlet of the ultra-low concentration gas dual oxidation device, an outlet switching valve is arranged at the outlet of the ultra-low concentration gas dual oxidation device, the outlet of the ultra-low concentration gas dual oxidation device is connected to a chimney I through a main induced draft fan, the ultra-low concentration gas dual oxidation device is also connected to a waste heat boiler through a pipeline, the waste heat boiler is respectively connected to the boiler induced draft fan and the air preheater, the boiler induced draft fan is connected to the chimney II, an antifreeze flue gas valve is arranged between the waste heat boiler and the air preheater, a smoke exhaust regulating valve is arranged between the waste heat boiler and the boiler induced draft fan, and the air preheater is connected to the boiler induced draft fan.

[0007] Furthermore, more than two groups of mixing tubes are arranged in the mixer, each group of mixing tubes includes an inner mixing tube, a middle mixing tube and an outer mixing tube, and mixing tube regulating valves are arranged between the inner mixing tube, the middle mixing tube and the outer mixing tube and the gas extraction and exhaust pipe respectively. There are several spray holes on the mixing tubes, and the mixing tubes are arranged side by side in the pipe of the mixer.

[0008] Furthermore, the diameter Φ of the spray hole on the mixing tube is 3mm~5mm; the spray hole is oriented toward the center of the pipeline and deflected toward the direction of the exhaust gas flow, and the angle α between the spray hole and the diameter direction of the exhaust gas pipeline is 20º~30º.

[0009] Furthermore, the diameter of the mixer pipe is D, and each mixing tube is spaced A from front to back and B from top to bottom, satisfying A=0.4D~0.6D, B=0.3D~0.35D; the spacing between two adjacent groups of mixing tubes is C, satisfying C=1.2D~1.5D.

[0010] Furthermore, the exhaust gas ejection speed is 40m / s~50m / s.

[0011] Furthermore, the mixer is connected to the chimney I, and an emergency relief valve is provided between the mixer and the chimney I.

[0012] Furthermore, the ultra-low-concentration gas dual oxidation device includes left and right heat storage chambers, low-temperature heat storage ceramics are arranged in the heat storage chambers, catalysts are arranged on the low-temperature heat storage ceramics, the left and right heat storage chambers are respectively provided with inlets and outlets, inlets of the left and right heat storage chambers of the ultra-low-concentration gas dual oxidation device are respectively provided with inlet switching valves V01 and inlet switching valves V02, and outlets of the left and right heat storage chambers of the ultra-low-concentration gas dual oxidation device are respectively provided with outlet switching valves V03 and outlet switching valves V04.

[0013] Compared with the prior art, the structure of the mixing device of the present invention can ensure that the concentration of the extracted gas is quickly reduced to below 3%, ensuring the safety of the ultra-low concentration gas oxidation device. If there are no anti-freezing measures for the pipeline, the freezing of the pipeline in winter can easily cause safety accidents. If other heating methods are used, such as electric heating and steam heating, additional investment in heating equipment and additional heating energy consumption are required. The present invention uses part of the exhaust flue gas to solve the pipeline anti-freezing problem, uses the waste heat of the exhaust flue gas, has no heating energy consumption, and has the lowest operating cost; at the same time, it is beneficial to improve the thermal efficiency of the oxidation device system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural connection diagram of the present invention;

[0015] Figure 2 is a schematic diagram of the mixer structure;

[0016] Figure 3 Schematic diagram of the nozzle structure;

[0017] In the figure: 1-blower, 2-mixer, 3-methane concentration sensor, 4-inlet switching valve, 5-low-temperature heat storage ceramics, 6-catalyst, 7-low-temperature heat storage ceramics, 8-ultra-low concentration gas dual oxidation device, 9-outlet switching valve, 10-main induced draft fan, 11-chimney, 12-waste heat boiler, 13-smoke exhaust regulating valve, 14-boiler induced draft fan, 15-chimney, 16-antifreeze flue gas valve, 17-air preheater, 18-emergency relief valve, 19-gas extraction and exhaust pipe, 20-mixing pipe regulating valve, 21-mixing pipe, 22-spray hole. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] like Figure 1 As shown, an ultra-low concentration gas dual oxidation heating system includes a mixer 2 connected to a gas extraction pipeline 19, the mixer 2 is communicated with air through an air preheater 17, the mixer 2 is connected to an ultra-low concentration gas dual oxidation device 8, an inlet switching valve 4 is arranged at the inlet of the ultra-low concentration gas dual oxidation device 8, the outlet of the ultra-low concentration gas dual oxidation device 8 is connected to a chimney I11 through a main induced draft fan 10, an outlet switching valve 9 is arranged at the outlet of the ultra-low concentration gas dual oxidation device 8, the ultra-low concentration gas dual oxidation device 8 is also connected to a waste heat boiler 12 through a pipeline, the waste heat boiler 12 is respectively connected to a boiler induced draft fan 14 and an air preheater 17, the boiler induced draft fan 14 is connected to a chimney II15, an antifreeze flue gas valve 16 is arranged between the waste heat boiler 12 and the air preheater 17, a smoke exhaust regulating valve 13 is arranged between the waste heat boiler 12 and the boiler induced draft fan 14, and the air preheater 17 is connected to the boiler induced draft fan 14. The mixer 2 is connected to the chimney I11, and an emergency relief valve 18 is provided between the mixer 2 and the chimney I11.

[0020] like Figure 2 As shown, more than two groups of mixing tubes 21 are arranged in the mixer 2. The mixing tubes 21 are arranged side by side in the pipeline of the mixer 2. Each group of mixing tubes 21 includes an inner mixing tube, a middle mixing tube and an outer mixing tube. Mixing tube regulating valves 20 are arranged between the inner mixing tube, the middle mixing tube and the outer mixing tube and the gas extraction pipeline respectively. There are a plurality of spray holes 22 on the mixing tube 21.

[0021] A blower, air preheater and mixer are set up. Fresh air is preheated by the air preheater and mixed with the exhaust gas in the mixer. After mixing, the gas concentration is controlled below 3%, which can ensure the safe operation of the oxidation device. A methane concentration sensor is set after the mixer. After mixing, the concentration is controlled at 0.3% to 3% (the specific concentration is determined according to the heating load).

[0022] Electric butterfly valve is used as the reversing control valve. The inlet switching valves V01 and V02 are used to control the connection and disconnection between the gas inlet pipeline and the heat storage chambers on the left and right sides of the oxidation device, that is, to control the gas entering the oxidation device; the outlet switching valves V03 and V04 are used to control the connection and disconnection between the gas outlet pipeline and the heat storage chambers on both sides of the oxidation device A and B, that is, to control the low-temperature flue gas to be discharged from the oxidation device. The inlet switching valve and the outlet switching valve cooperate to control the flow direction of ultra-low concentration gas and automatically switch direction regularly. The switching action sequence of the switching valve is as follows: V04 is closed, V01 is closed and V02 is opened at the same time after it is in place, and V03 is opened after both are in place; V03 is closed when reversing again, V02 is closed and V01 is opened at the same time after it is in place, and V04 is opened after both are in place. The reversing time is 3min~30min.

[0023] The low-temperature flue gas is discharged into the atmosphere through the main induced draft fan and chimney; the main induced draft fan is used to control the flue gas flow rate discharged from the oxidation device and adjust the frequency.

[0024] An emergency relief valve is installed before the reversing valve at the inlet of the oxidation device to directly discharge ultra-low concentration gas in emergency situations.

[0025] Part of the high-temperature flue gas enters the waste heat boiler through the high-temperature flue from the middle of the oxidation device. After the flue gas cools down in the waste heat boiler, it is discharged into the atmosphere through the exhaust regulating valve, boiler induced draft fan, and chimney. The boiler induced draft fan is used to control the flow of high-temperature flue gas entering the waste heat boiler and is adjusted by frequency conversion.

[0026] A flue gas bypass and an antifreeze flue gas valve are set at the outlet of the waste heat boiler. In winter, the exhaust gas regulating valve is closed and the antifreeze flue gas valve is opened. After the flue gas is cooled in the waste heat boiler, it is further cooled through the antifreeze flue gas valve and the air preheater and discharged into the atmosphere through the boiler induced draft fan and chimney. In the air preheater, the flue gas is used to preheat the fresh air to prevent the pipe from freezing.

[0027] The mixer can be divided into two or three stages; each stage of mixed gas consists of a group of mixing tubes (inner mixing tube, middle mixing tube, outer mixing tube); a mixing tube regulating valve is set between each mixing tube and the gas extraction pipeline to adjust the gas extraction flow of each mixing tube. There are several spray holes on the mixing tube; the extracted gas is sprayed out from the spray holes on the mixing tube and quickly mixed with the air to form an ultra-low concentration gas with a concentration of less than 3%. The diameter of the spray hole on the mixing tube should be 3mm~5mm; the spray hole is deflected toward the center of the pipeline and the direction of the gas extraction flow, and the angle α with the diameter direction of the gas extraction pipeline should be 20º~30º; the gas extraction speed is 40m / s~50m / s. The diameter of the mixer tube is D; the distance between each mixing tube is A from front to back and B from top to bottom; it should also meet A=0.4D~0.6D, B=0.3D~0.35D. The distance between the two groups of mixing tubes is C; it should satisfy C=1.2D~1.5D.

[0028] Rapid mixing device structure and design parameters:

[0029] A key point to ensure the safety of the dual oxidation device is to ensure that the gas concentration in the system is less than 3%. Through the specific structure of the rapid mixing device, the low-concentration gas is quickly mixed with fresh air, and the concentration is reduced to less than 3% in a very short distance to become an ultra-low concentration gas, thereby improving the safety of the system.

[0030] An air preheater is provided at the mixer inlet:

[0031] An air preheater is installed at the mixer inlet. In winter, the exhaust hot flue gas passes through the heat exchanger before being discharged. The air preheater preheats the air to increase the temperature of the ultra-low concentration gas to be oxidized, which not only solves the problem of pipeline icing in winter, but also improves the thermal efficiency of the device.

[0032] The present specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An ultra-low concentration gas dual oxidation heating system, characterized in that: The invention comprises a mixer (2) connected to a gas extraction pipeline (19), the mixer (2) being connected to air via an air preheater (17), the mixer (2) being connected to an ultra-low concentration gas dual oxidation device (8), an inlet switching valve (4) being arranged at the inlet of the ultra-low concentration gas dual oxidation device (8), an outlet of the ultra-low concentration gas dual oxidation device (8) being connected to a chimney I (11) via a main induced draft fan (10), an outlet switching valve (9) being arranged at the outlet of the ultra-low concentration gas dual oxidation device (8), and a gas outlet of the ultra-low concentration gas dual oxidation device (8) being connected to a chimney I (11) via a main induced draft fan (10). The double oxidation device (8) is also connected to the waste heat boiler (12) through pipelines. The waste heat boiler (12) is respectively connected to the boiler induced draft fan (14) and the air preheater (17). The boiler induced draft fan (14) is connected to the chimney II (15). An antifreeze flue gas valve (16) is provided between the waste heat boiler (12) and the air preheater (17). A smoke exhaust regulating valve (13) is provided between the waste heat boiler (12) and the boiler induced draft fan (14). The air preheater (17) is connected to the boiler induced draft fan (14). More than two groups of mixing tubes (21) are arranged in the mixer (2), each group of mixing tubes (21) comprises an inner mixing tube, a middle mixing tube and an outer mixing tube, mixing tube regulating valves (20) are arranged between the inner mixing tube, the middle mixing tube and the outer mixing tube and the gas extraction and discharge pipeline respectively, a plurality of spray holes (22) are arranged on the mixing tubes (21), and the mixing tubes (21) are arranged side by side in the pipeline of the mixer (2); The diameter Φ of the spray hole (22) on the mixing pipe (21) is 3 mm to 5 mm; the spray hole (22) is oriented toward the center of the pipeline and deflected toward the direction of the gas extraction flow, and the angle α between the spray hole (22) and the diameter direction of the gas extraction pipeline is 20° to 30°; The diameter of the pipe of the mixer (2) is D, the front-to-back distance of each mixing pipe is A, and the top-to-bottom distance is B, satisfying A=0.4D~0.6D, B=0.3D~0.35D; the spacing between two adjacent groups of mixing pipes (21) is C, satisfying C=1.2D~1.5D; The gas exhaust speed is 40m / s~50m / s.

2. The ultra-low concentration gas dual oxidation heating system according to claim 1 is characterized in that: The mixer (2) is connected to the chimney I (11), and an emergency relief valve (18) is provided between the mixer (2) and the chimney I (11).

3. The ultra-low concentration gas dual oxidation heating system according to claim 1 is characterized in that: The ultra-low-concentration gas dual oxidation device (8) comprises left and right heat storage chambers, wherein low-temperature heat storage ceramics are arranged in the heat storage chambers, and catalysts (6) are arranged on the low-temperature heat storage ceramics. The left and right heat storage chambers are respectively provided with an inlet and an outlet. The inlets of the left and right heat storage chambers of the ultra-low-concentration gas dual oxidation device (8) are respectively provided with inlet switching valves (4), and the outlets of the left and right heat storage chambers of the ultra-low-concentration gas dual oxidation device (8) are respectively provided with outlet switching valves (9).

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