Improved coal mine low-concentration gas methane destruction device

Abstract

The utility model relates to the coal mine well wind processing technical field relates to the improved coal mine low concentration gas methane destruction device, including oxidation bed, air inlet device, air induction device, the air inlet device provides the constant flow of air inlet gas flow that can set, the air induction device provides the air induction gas flow of adjustable pressure, the oxidation bed connects gas separation membrane structure, gas separation membrane structure connects air inlet pipeline and the air outlet's retentate gas pipeline, through gas pipeline, the retentate gas pipeline connects the main air inlet of oxidation bed, the air outlet of oxidation bed connects the post-reaction gas pipeline, the post-reaction gas pipeline connects through gas pipeline, due to not need additional high concentration gas gas under the condition of low methane concentration again, avoided unnecessary energy waste, reduced the work burden of oxidation bed. Methane is reacted step by step under the condition of low oxygen and low methane concentration respectively, reduces the explosion risk under the condition of the final complete reaction of methane.

Description

Technical Field

[0001] This utility model relates to the field of methane treatment technology in coal mine ventilation, and more specifically, to an improved coal mine low-concentration methane destruction device. Background Technology

[0002] Coal mine exhaust gas contains less than 1.5% methane, and some extracted gas contains less than 6% methane, neither of which can be directly utilized. Methane is a strong greenhouse gas, and direct emission poses a significant environmental hazard. Our unit has developed a technology for treating low-concentration methane in coal mine exhaust gas. The methane in the gas passes through an oxidation bed, where it undergoes a redox reaction to produce water and carbon dioxide before being discharged. For details, please refer to utility model patent CN101435338B - Method and Device for Destroying Low-Concentration Methane in Coal Mine Exhaust Gas. This device oxidizes and destroys methane that cannot be directly used, reducing environmental harm.

[0003] The above-mentioned device still has some shortcomings and needs further improvement:

[0004] In coal mines, the methane concentration in exhaust air or low-concentration coal mines is unstable. When the methane concentration in the intake air is too low, the oxidation bed operates normally, but the reaction rate decreases or even stops, failing to effectively destroy methane. In this situation, the aforementioned device adds a higher concentration of methane gas to the intake air. This results in two consequences: firstly, usable methane gas is destroyed, wasting energy; secondly, it increases the unnecessary amount of methane to be destroyed in the oxidation bed and the total gas volume, reducing processing efficiency. Utility Model Content

[0005] The main purpose of this invention is to provide an improved coal mine low-concentration methane destruction device that ensures the normal operation of the oxidation bed without adding methane, avoids unnecessary methane addition, and improves efficiency.

[0006] The overall concept of this invention is to increase the concentration of methane before carrying out the oxidation reaction, and to solve the problem of explosion risk encountered when increasing the concentration of methane.

[0007] The overall improvement scheme of this utility model is as follows:

[0008] By adding a membrane separation structure to the existing oxidation bed, when the methane content is low, the gas separation membrane structure diverts the excess oxygen inlet gas flow. The methane-containing permeate gas exits through the gas separation membrane structure and then enters the oxidation bed. The remaining gas does not participate in the reaction and therefore does not carry away the heat after the reaction, which helps to maintain the temperature of the oxidation bed and ensure the normal progress of the reaction.

[0009] The intake air device provides a settable, constant flow rate, while the exhaust air device provides an adjustable pressure exhaust airflow. The exhaust air device adjusts its pressure according to the methane content of the intake airflow; within a certain range, the lower the methane content, the greater the negative pressure provided by the exhaust air device. The greater the negative pressure, the greater the pressure difference across the gas separation membrane, allowing more gas to pass through the membrane and further increasing the methane content in the residual gas. Simultaneously, due to the separation of some oxygen, the oxygen content in the residual gas is significantly reduced. Although the methane content increases, the insufficient oxygen makes it difficult to reach explosion conditions, thus reducing the risk of explosion.

[0010] The oxidation bed structure was improved, changing the overall reciprocating oxidation reaction to a partial reciprocating reaction. The oxidation bed was modified into a ring-shaped multi-layered structure, with the methane reaction becoming more complete towards the center. Airflow is drawn from the center of the oxidation bed and then discharged. Airflow is drawn from the periphery of the oxidation bed and then enters from the bottom, supplemented by some through air to replenish oxygen, but still maintaining oxygen-deficient conditions. This cycle ensures a more complete reaction and improves the continuity of equipment operation.

[0011] A further improvement involves drawing back the gas flow from the gas flow branch and merging it into the circulating gas flow of the reaction gas, thereby providing sufficient oxygen to ensure complete reaction of methane.

[0012] A further improvement involves diverting a supplementary branch airflow from the gas flow path and directing it into the center of the bottom of the oxidation bed. In the peripheral region of the oxidation bed, methane is oxidized in the absence of sufficient oxygen; however, in the central axis region of the oxidation bed, oxygen is abundant while methane content is low. This ensures complete methane reaction while reducing the risk of explosion.

[0013] The application of the technical solution of this utility model has the following technical effects:

[0014] (1) Before entering the oxidation bed, the methane enrichment treatment is carried out on the exhaust gas or extracted gas of coal mine with low methane concentration. There is no need to add high concentration gas when the methane concentration is low, which avoids unnecessary energy waste and reduces the workload of the oxidation bed.

[0015] (2) After methane enrichment treatment, a reaction with sufficient oxygen is transformed into a combination of a reaction with insufficient oxygen and a reaction with low methane content. Methane reacts stepwise under low oxygen and low methane concentration conditions, thereby reducing the risk of explosion when methane finally reacts completely. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:

[0017] Figure 1 A schematic diagram illustrating the basic principle of an improved coal mine low-concentration methane destruction device is shown.

[0018] Figure 2 A schematic diagram of the device with an increased circulating flow of reactive gas is shown.

[0019] Figure 3 A schematic diagram of a device with increased reflux branch airflow under sufficient oxygen conditions in an oxidation bed is shown.

[0020] Figure 4 A schematic diagram of a device for adding supplementary branch airflow when oxygen is insufficient around the oxidation bed is shown.

[0021] Figure 5 A schematic diagram of the cross-sectional structure of the oxidation bed is shown.

[0022] The above figures include the following reference numerals:

[0023] 1. Oxidation bed;

[0024] 11. Thermal insulation layer;

[0025] 12. Thermal storage medium;

[0026] 13. Heat exchanger;

[0027] 14. Heater;

[0028] 15. Main air intake;

[0029] 2. Gas membrane separator;

[0030] 3. Roots blower;

[0031] 4. Centrifugal fan;

[0032] A. Air intake airflow;

[0033] B. Residual gas;

[0034] C. Through gas;

[0035] D. Gas produced after the reaction;

[0036] E. Reaction gas circulation flow;

[0037] F. Airflow in the return branch;

[0038] G. Supplement the airflow of the branch. Detailed Implementation

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] Example 1

[0041] This embodiment is a basic model, used to illustrate the basic principle of an improved coal mine low-concentration methane destruction device.

[0042] like Figure 1 As shown, the main body of the device consists of an oxidation bed 1 and a gas membrane separator 2 connected to it via pipelines. The incoming airflow A passes through the gas membrane separator 2, forming residual gas B and through gas C. Through gas C is mainly composed of oxygen and carbon dioxide, while residual gas B is mainly composed of nitrogen, methane, and residual oxygen. Residual gas B enters the oxidation bed 1 for oxidation, where the methane reacts to form water and carbon dioxide, resulting in post-reaction gas D. Post-reaction gas D then merges with through gas C and is finally discharged by the induced draft fan.

[0043] The intake airflow A, residual gas B, through gas C, and post-reaction gas D correspond to the intake air pipeline, residual gas pipeline, through gas pipeline, and post-reaction gas pipeline, respectively, and each pipeline is equipped with an electrically controlled valve. The valve between the through gas pipeline and the gas membrane separator can be used in conjunction with the induced draft fan to adjust the pressure difference between the through gas and the residual gas.

[0044] After the airflow passes through the gas membrane separator 2, the gas does not pass through the oxidation bed and does not absorb the heat from the combustion of methane, which helps the oxidation bed 1 maintain the temperature required for the reaction.

[0045] The incoming airflow A maintains a fixed air volume at the inlet of the gas membrane separator 2, which can be provided by the Roots blower 3 and its auxiliary valves. The negative pressure of the gas C is regulated by a centrifugal blower and its auxiliary valves. When the power of the centrifugal blower 4 is increased, the gas membrane separator 2 allows more gas molecules to pass through the separation membrane. With a higher proportion of gas passing through, the methane content in the residual gas increases. Therefore, the centrifugal blower can be adjusted according to the methane content in the incoming airflow to keep the methane content in the residual gas within a certain concentration range.

[0046] During the gas separation process of the gas membrane separator 2, carbon dioxide passes through relatively quickly, resulting in a significant reduction in the carbon dioxide content in the residual gas. This is beneficial for the reaction of methane and can lower the reaction temperature. Simultaneously, during the adjustment of the gas flow rate in the gas membrane separator 2, the main change in the gas is the change in the oxygen flow rate. Although the methane concentration increases after the negative pressure increases, the high oxygen flow rate reduces the oxygen content in the residual gas, making it difficult to reach the explosion limit conditions.

[0047] Figure 1 The gas membrane separator 2 is shown as being separated from the oxidation bed, but it can also be a structure that integrates the gas membrane separation structure with the oxidation bed.

[0048] Example 2

[0049] To ensure complete methane reaction, the oxidation bed needs to be designed to be relatively large. Previously, our company achieved a smaller oxidation bed by repeatedly passing the reactant gas through it.

[0050] In this embodiment, as Figure 2 As shown, the optimization based on Example 1 involves changing the oxidation bed to a cylindrical shape, placing the main air inlet at the lower-middle position of the side of the oxidation bed, and placing the outlet for the reacted gas at the center of the top of the oxidation bed. A reaction gas circulation pipeline is led out from the edge of the top of the oxidation bed to the middle of the axis, and the reaction gas circulation pipeline is connected to the residual gas pipeline. The air intake method is changed to a method of lateral air intake from all four sides, gradually flowing towards the center and top. The reacted gas is discharged from the top, and a reaction gas circulation flow E is led out from the edge of the top to the middle of the axis.

[0051] In the top layer of the reactor, the reaction is fully complete at the center, and becomes less complete towards the periphery. The reaction gas circulating flow E merges with the residual gas B and re-enters the oxidation bed 1 for reaction, thereby improving the reaction efficiency and reducing the size of the oxidation bed and space occupation.

[0052] like Figure 3 As shown, in order to further ensure the complete reaction of methane, a reflux branch gas flow F can be drawn out from the gas C, and then merged with the residual gas B. After replenishing the residual gas B with oxygen, the gas enters the oxidation bed.

[0053] but Figure 3 The reaction process shown requires a sufficient supply of oxygen; if oxygen is insufficient, methane cannot react completely. However, when the methane concentration is high and oxygen is sufficient, the methane concentration can easily reach the explosive limit, increasing the risk.

[0054] Therefore, this embodiment is further improved by changing an oxygen-sufficient reaction into a combination of an oxygen-deficient reaction and a low-methane-content reaction.

[0055] For details, please refer to the following: Figure 4 A supplementary gas flow G is drawn from gas C and enters the oxidation bed from the center of the bottom. The surrounding area of ​​the oxidation bed remains oxygen-deficient, making it difficult to reach the explosive concentration. In the central region of the oxidation bed, due to partial reaction of methane, the methane concentration decreases, and even under sufficient oxygen conditions, it is still difficult to reach the concentration required for an explosion. Through the above improvements, methane reacts gradually under low oxygen and low methane concentration conditions, thereby reducing the explosion risk when methane has completely reacted.

[0056] In this embodiment, the reaction gas circulation flow E, the return branch flow F, and the supplementary branch flow G correspond to the reaction gas circulation pipeline, the return branch pipeline, and the supplementary branch pipeline, respectively.

[0057] The working principle of the oxidation bed still follows that of the oxidation bed in our patent CN101435338B - Method and Device for the Destruction of Low-Concentration Methane Gas in Coal Mines. Adjustments are made to the inlet and outlet methods and the shape and position of the internal components. Its cross-section can be referenced. Figure 5 The outer layer is an insulation layer 11, and the inner layer consists of a cross-arranged annular heat storage carrier 12 and a heat exchanger 13. The center is a heater 14, and the main air inlet 15 is located on the side wall of the oxidation bed. When the oxidation bed starts working, the heater 14 is required for preheating. Once the reaction is proceeding normally, the heater 14 is turned off, and the heat is entirely provided by the methane reaction.

[0058] Working Process: Taking the device of Example 2 as an example, the gas separation membrane structure is used to separate the incoming airflow into a through airflow mainly composed of oxygen and carbon dioxide, and a permeate gas mainly composed of nitrogen, methane, and residual oxygen. The permeate gas enters the oxidation bed for reaction and then merges back into the through airflow to form an induced draft airflow entering the induced draft device. The incoming airflow maintains a constant flow rate, and the pressure of the induced draft airflow is adjusted according to the methane content of the incoming airflow. The higher the methane content of the incoming airflow, the stronger the negative pressure provided by the induced draft device, the larger the proportion of the through airflow, and the higher the methane content in the permeate gas. Since the through gas does not pass through the oxidation bed, it does not absorb the heat of methane combustion, which helps the oxidation bed maintain the temperature required for the reaction and ensures that the reaction proceeds normally without the need to add high-concentration methane extraction gas.

[0059] The circulating gas stream of the reaction gas drawn from the oxidation bed is incorporated into the residual gas, which can improve reaction efficiency and help reduce the size of the oxidation bed.

[0060] In one scenario, the return gas flow from the gas flow branch is drawn off and merged into the circulating gas flow of the reaction gas, thereby providing sufficient oxygen to ensure complete reaction of the methane.

[0061] In another scenario, a supplementary gas flow is drawn from the gas flow branch and enters the center of the bottom of the oxidation bed. In the peripheral region of the oxidation bed, methane is oxidized in the absence of sufficient oxygen; in the central axis region of the oxidation bed, oxygen is abundant while the methane content is low. This ensures complete methane reaction while reducing the risk of explosion.

[0062] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. An improved coal mine low-concentration methane destruction device, comprising an oxidation bed, an air inlet device, and an induced draft device, characterized in that, The air intake device provides a settable constant airflow. The air extraction device provides an adjustable pressure airflow. The oxidation bed is connected to a gas separation membrane structure; the gas separation membrane structure is connected to an air inlet pipe and an outlet residual gas pipe and a through gas pipe; the residual gas pipe is connected to the main air inlet of the oxidation bed; the air outlet of the oxidation bed is connected to a post-reaction gas pipe, and the post-reaction gas pipe is connected to a through gas pipe. The exhaust fan is used to adjust the pressure according to the methane content of the intake airflow; the lower the methane content, the greater the negative pressure provided by the exhaust fan.

2. The improved coal mine low-concentration methane destruction device as described in claim 1, characterized in that, The main body of the oxidation bed is cylindrical. The main air inlet is located at the lower middle position of the side of the oxidation bed. The outlet of the gas after reaction is located at the center of the top of the oxidation bed. A reaction gas circulation pipeline is led out from the edge of the top of the oxidation bed to the middle of the axis. The reaction gas circulation pipeline is connected to the residual gas pipeline.

3. The improved coal mine low-concentration methane destruction device as described in claim 2, characterized in that, A return branch pipe is led out from the gas pipeline, and the return branch pipe is connected to the reaction gas circulation pipeline.

4. The improved coal mine low-concentration methane destruction device as described in claim 2, characterized in that, A supplementary branch line is led out from the gas pipeline, and the supplementary branch line is connected to the bottom center of the oxidation bed.

5. The improved coal mine low-concentration methane destruction device as described in any one of claims 2-4, characterized in that, The oxidation bed has an outer insulation layer, an inner ring of heat storage carriers and heat exchangers arranged in an alternating pattern, and a heater at the center.

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