Device for realizing coal mine shaft heat preservation based on low-concentration gas pulsating combustion
By using low-concentration gas pulsed combustion technology and special flue design, the problem of incomplete combustion of low-concentration gas has been solved, achieving efficient heat preservation and environmental protection of coal mine shafts.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA UNIV OF MINING & TECH
- Filing Date
- 2023-11-13
- Publication Date
- 2026-07-07
AI Technical Summary
In existing technologies, low-concentration methane is difficult to burn stably and efficiently, leading to resource waste and environmental pollution. Furthermore, coal mine shaft insulation is difficult after coal-fired boilers are shut down.
By employing low-concentration methane pulsed combustion technology, combined with specially designed flues and turbulence devices, the full combustion of low-concentration methane is achieved, and the heat generated from the combustion is used for insulation of the coal mine shaft.
It achieves efficient combustion and utilization of low-concentration methane, reduces greenhouse gas emissions, provides wellbore insulation, avoids the hazards of incomplete combustion, and saves costs.
Smart Images
Figure CN117514342B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of coal mine shaft insulation devices, and in particular to a device for achieving coal mine shaft insulation based on flue gas from low-concentration methane pulsating combustion. Background Technology
[0002] Coal mine shaft insulation is an important task for safe production in coal mines, and it is also an indispensable part of safe production in winter, especially in northern regions north of the Huai River.
[0003] Currently, coal-fired boilers are generally used as the heat source for shaft insulation. However, due to national environmental protection policies, small coal-fired boilers used for shaft insulation in coal mines are facing shutdown. Therefore, how to ensure safe production in shafts during winter after the shutdown of coal-fired boilers has become an urgent technical problem for coal mines in northern regions.
[0004] On the other hand, in order to reasonably solve the safety problem in mines, gas drainage is usually used to reduce the concentration of methane in ventilation to below 1%, which is a safe level. However, in the process of methane drainage in Chinese coal mines, due to the single method of gas drainage, a large amount of air is mixed in, and the drainage volume fluctuates greatly, most of the extracted methane is low-concentration methane with a concentration of less than 30%. Among them, the extracted methane with a concentration of less than 8% accounts for more than 70% of the total extracted volume. Since this part of the methane is within the explosive concentration range, it is difficult to stably and efficiently burn and utilize it using conventional combustion methods before releasing it into the atmosphere.
[0005] Methane, the main component of natural gas, has a greenhouse effect equivalent to 24.6 times that of CO2 and a destructive impact on the ozone layer equivalent to 7 times that of CO2. The large amounts of low-concentration natural gas released annually that cannot be utilized not only result in a severe waste of this finite non-renewable resource but also exacerbate air pollution and the greenhouse effect. Natural gas, as a high-quality energy source, has a calorific value of approximately 35,000 kJ / Nm³. 3 Coalbed methane (CBM) is comparable to conventional natural gas and can be used as fuel and chemical feedstock. However, because oxygen is a flammable additive, its introduction increases the explosion hazard of CBM, posing significant challenges to its processing and transportation.
[0006] Currently, medium-to-high concentration methane (CH4>30%) accounts for about 6%, with a utilization rate exceeding 90%. Low-concentration methane accounts for about 94%, but its utilization rate is less than 35%. Due to the extremely low concentration of methane in low-concentration methane, its utilization is difficult. The main utilization methods are regenerative thermal oxidation and co-combustion power generation with high-concentration methane. However, these methods also have relatively low utilization efficiency, resulting in most low-concentration methane being directly discharged into the atmosphere, causing huge waste of resources and significant environmental damage.
[0007] Low-concentration methane gas, ranging from 4% to 10%, is rare and at its explosive limit, making it difficult to achieve stable combustion and efficient utilization through conventional combustion methods. Therefore, it is usually directly discharged into the atmosphere, resulting in a huge waste of energy and serious environmental pollution.
[0008] Pulsed combustion, as a novel combustion technology, has advantages such as high combustion intensity, high heat transfer efficiency, and low pollutant emissions. Compared with steady-state combustion, its technical advantages include: (1) High combustion intensity: The thermo-acoustic coupling effect generates a strong pulsed airflow, which enhances the mixing, mass transfer, and heat transfer processes between fuel and hot combustion products, resulting in a combustion intensity as high as 10,000 to 50,000 kW / m³. 3 (2) High heat transfer efficiency: The thermo-acoustic coupling effect in the combustion chamber makes the thermal boundary layer of the pipe wall thinner, reducing the resistance to heat transfer and improving the heat transfer coefficient; (3) Low pollutant emissions: The pulse flow in the burner can make the mixture burn completely, reducing the content of polluting gases in the exhaust gas; (4) Simple structure and low cost.
[0009] If pulsed combustion technology is used to achieve efficient combustion of low-concentration methane, and combined with a specially designed flue, and the heat generated is used for insulation of coal mine shafts, it can save costs and protect the environment. However, there are no relevant technical means in the current technology. Summary of the Invention
[0010] The purpose of this invention is to provide a device for heat preservation of coal mine shafts based on flue gas from the pulsed combustion of low-concentration methane, which solves the technical problems existing in the prior art. The device utilizes pulse combustion technology to fully combust low-concentration methane and uses the heat generated by the combustion to achieve heat preservation of coal mine shafts.
[0011] To achieve the above objectives, the present invention provides the following solution:
[0012] This invention discloses a device for heat preservation of coal mine shafts based on flue gas from low-concentration methane pulsed combustion, including a flue, the outlet of which is located at the mine shaft opening, and a plurality of pulsed burners respectively provided at the inlet of the flue and on both sides of the flue.
[0013] Preferably, the flue is constructed of refractory bricks or refractory cement.
[0014] Preferably, the cross-section of the flue is rectangular. However, to enhance turbulence, the inner wall of the flue can be made irregular, such as wavy, along the axial direction to enhance the combustion process.
[0015] Preferably, the outer side of the pulsed burner is provided with a heat insulation layer.
[0016] Preferably, the pulsed burners located on both sides of the flue are symmetrically or staggeredly distributed, and the pulsed burners located on both sides of the flue are at an angle to the axial direction of the flue.
[0017] Preferably, the included angle between the axes of the pulsed burners located on both sides of the flue is the first included angle;
[0018] The first included angle is 90°-150°.
[0019] Preferably, a number of flow disturbance devices are arranged sequentially along the flue gas flow direction inside the flue.
[0020] Preferably, the turbulence-disrupting device has a triangular prism structure.
[0021] Preferably, the included angle of the turbulence device in the direction of the flue gas inlet is a second included angle, and the second included angle is 30°-60°;
[0022] The width of the side of the turbulence device near the flue outlet is 'a', and the width of the flue is 'b', where b / 5 ≤ a ≤ b / 3.
[0023] Preferably, the flue is provided with multiple flues, and the air outlets of the multiple flues converge at the air inlet of the main pipe, and the air outlet of the main pipe is located at the mine shaft opening.
[0024] The present invention achieves the following technical effects compared to the prior art:
[0025] This invention, by incorporating pulsed burners, effectively utilizes low-concentration methane gas through combustion. This reduces greenhouse gas emissions during coal mining, protecting the environment, and provides thermal energy for mine shaft insulation. Simultaneously, arranging several pulsed burners at the flue's inlet and both sides, with the burners on the sides at a certain angle to the flue, enhances the turbulence of the high-temperature flue gas and increases its residence time. Furthermore, multiple turbulence devices are installed within the flue to strengthen combustion and prevent the production of carbon monoxide due to incomplete combustion, thus avoiding carbon monoxide poisoning among workers. The high-temperature flue gas generated by combustion is directly delivered to the mine shaft. Utilizing the negative pressure at the mine shaft and the periodic fluctuations in flue gas pressure generated by the pulsed burners, it enhances the natural mixing with the surrounding cold air, raising the temperature of the mixture and achieving an overall increase in the temperature of the mine's ventilation system, thereby achieving the purpose of coal mine shaft insulation.
[0026] This invention solves the problems of gas explosion upon contact with an open flame during gas utilization and incomplete combustion due to low heat intensity during combustion, completely eliminating the hazards caused by incomplete combustion. Furthermore, because the implementation scheme of this invention completely eliminates the problem of incomplete gas combustion, the flue gas from the combustion of low-concentration gas can be directly and thoroughly mixed with the surrounding cold air using pressure and temperature differences, avoiding the use of heat exchangers or high-power electric heaters in other technical solutions, resulting in significant energy-saving effects and cost advantages. Attached Figure Description
[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0028] Figure 1 This is a top view of a device for heat preservation of coal mine shafts based on flue gas from low-concentration methane pulsating combustion, according to an embodiment of the present invention.
[0029] Figure 2 This is a front view of a device for heat preservation of coal mine shafts based on flue gas from low-concentration methane pulsating combustion, according to an embodiment of the present invention.
[0030] Figure 3 This is a side view of a device for heat preservation of coal mine shafts based on flue gas from low-concentration methane pulsating combustion, according to an embodiment of the present invention.
[0031] In the diagram: 1-Pulsating burner; 2-Insulation layer; 3-Flue; 4-Refractory brick; 5-Breath-inducing device. Detailed Implementation
[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0033] The purpose of this invention is to provide a device for heat preservation of coal mine shafts based on flue gas from the pulsed combustion of low-concentration methane, which solves the technical problems existing in the prior art. The device utilizes pulse combustion technology to fully combust low-concentration methane and uses the heat generated by the combustion to achieve heat preservation of coal mine shafts.
[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0035] like Figures 1-3 As shown, this embodiment provides a device for heat preservation of coal mine shafts based on flue gas from low-concentration gas pulsed combustion. The device includes a flue 3, the outlet of which is located at the mine shaft opening. Several pulsed burners 1 are respectively provided at the inlet of the flue 3 and on both sides of the flue 3. The specific number of pulsed burners 1 can be adjusted by those skilled in the art based on the length and size of the flue 3 and the heat load of the coal mine shaft heat preservation. For the pulse burner 1, an existing low-concentration gas pulse burner can be selected, such as the "Low-concentration Gas Pulsating Burner with Wing Tube" disclosed in patent number CN109945187A, which includes a gas distribution box with five gas burners on one side and a gas pulse supply pipe on the other side. Further details of its structure can be found in the original document and will not be elaborated here. Alternatively, it can be the "Low-concentration Gas Pulsating Burner with Improved Main Pipe" disclosed in patent number CN109945189A or the "Low-concentration Gas Pulsating Burner with Flame Stabilizer Structure" disclosed in patent number CN109915829B, etc. In actual use, the pulse burner 1 also needs to be connected to a low-concentration gas source to deliver the low-concentration gas to the pulse burner 1.
[0036] In actual use, the low-concentration methane is first fully combusted by the pulse burner 1, and the high-temperature flue gas after combustion is discharged into the flue 3. The high-temperature flue gas generated by combustion is then sent directly to the mine shaft. With the help of the negative pressure at the mine shaft, it mixes naturally with the surrounding cold air to increase the temperature of the mixture, thereby achieving an overall increase in the temperature of the mine ventilation system and achieving the purpose of heat preservation of the coal mine shaft.
[0037] In this embodiment, the flue 3 is constructed of refractory bricks 4 or refractory cement. The flue 3 constructed of refractory bricks 4 has the characteristic of high temperature resistance. It should be noted that the flue 3 is not only the channel for high-temperature flue gas to enter the coal mine shaft, but also the space for secondary reaction of incomplete combustion products. That is, the high-temperature flue gas that is not completely burned and discharged from the pulsed burner 1 can undergo secondary reaction in the flue 3.
[0038] In this embodiment, the cross-section of the flue 3 is rectangular. Of course, those skilled in the art can adjust the shape and size of the flue 3 according to actual conditions, and it is not limited to the one in this embodiment. For example, in order to enhance the degree of turbulence, the inner wall of the flue 3 can also be made irregular, such as wavy, along the axial direction to enhance the combustion process.
[0039] In this embodiment, the outer side of the pulse burner 1 is provided with a heat insulation layer 2. The material of the heat insulation layer 2 includes, but is not limited to, materials with heat insulation function such as aluminum iron silicate or quartz wool, so as to improve the thermal efficiency of the pulse burner 1.
[0040] In this embodiment, the pulsed burners 1 located on both sides of the flue 3 are symmetrically or staggeredly distributed. This embodiment adopts a symmetrical distribution, that is, the number of pulsed burners 1 located on both sides of the flue 3 is the same and they correspond one-to-one. In addition, the pulsed burners 1 located on both sides of the flue 3 are at an angle to the axial direction of the flue 3.
[0041] In this embodiment, the included angle between the axes of the pulsed burners 1 located on both sides of the flue 3 is the first included angle, which is twice the angle between the pulsed burners 1 and the axial direction of the flue 3. The purpose of this arrangement is to enhance the turbulence of the high-temperature flue gas and increase the residence time.
[0042] In this embodiment, the first included angle is 90°-150°, and those skilled in the art can select the specific angle of the first included angle according to actual needs.
[0043] In this embodiment, a plurality of flow-disrupting devices 5 are sequentially arranged within the flue duct 3 along the flue gas flow direction (i.e., from the inlet to the outlet). The number of flow-disrupting devices 5 corresponds one-to-one with the number of pulsed burners 1 on both sides of the flue duct 3, such as... Figure 1 As shown, there are three sets of pulsed burners 1 on both sides of the flue 3, and there are also three turbulence devices 5 in the flue 3. Each turbulence device 5 is located directly behind the intersection of the axial extension lines of the two pulsed burners 1 in each set.
[0044] In this embodiment, the turbulence device 5 is essentially a triangular prism structure, but it can also be other types of conical structures. The dimensions gradually increase along the direction from the air inlet to the air outlet of the flue 3. This arrangement causes the high-temperature flue gas to be diverted at the turbulence device 5, thereby enhancing the turbulence effect.
[0045] In this embodiment, as Figure 1 As shown, the angle between the baffle device 5 and the air inlet of the flue 3 (i.e., Figure 1 The left included angle of the central turbulence device 5 is the second included angle, which is 30°-60°.
[0046] The side of the turbulence device 5 closest to the exhaust port of the flue 3 (i.e. Figure 1 The width of the vertical line on the right side of the central turbulence device 5 is 'a', and the width of the flue 3 (i.e., Figure 1 The length of the vertical direction of the middle flue 3 is b, and b / 5≤a≤b / 3.
[0047] In this embodiment, multiple flues 3 are provided, arranged side by side, and their outlets converge at the inlet of a main pipe. The outlet of the main pipe is located at the mine shaft entrance. That is, the multiple flues 3 are branches of the main pipe, which mixes the flue gas from the multiple flues 3 together and discharges it into the mine. The mixing of the high-temperature flue gas discharged from the main pipe with the surrounding air is achieved through negative pressure generated by the mine's own ventilation fans. The mine's ventilation system and fans are conventional equipment in existing mines, so they will not be described in detail here. The mixed gas is ultimately used for coal mine shaft insulation.
[0048] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.
Claims
1. A device for heat preservation of coal mine shafts based on flue gas from low-concentration methane pulsed combustion, characterized in that: Includes a flue (3), the outlet of the flue (3) is located at the mine shaft opening, and the inlet of the flue (3) and both sides of the flue (3) are respectively provided with a number of pulse burners (1). The pulsed burners (1) located on both sides of the flue (3) are at an angle to the axial direction of the flue; The flue (3) is provided with multiple outlets, and the outlets of the multiple flues (3) converge at the inlet of the main pipe, and the outlet of the main pipe is located at the mine wellhead. The pulsed burners (1) located on both sides of the flue (3) are symmetrically or staggeredly distributed; Several turbulence devices (5) are arranged sequentially along the flue gas flow direction inside the flue (3).
2. The device for heat preservation of coal mine shafts based on flue gas from low-concentration methane pulsating combustion according to claim 1, characterized in that: The flue (3) is made of refractory bricks (4) or refractory cement.
3. The device for heat preservation of coal mine shafts based on flue gas from low-concentration methane pulsed combustion according to claim 1, characterized in that: The cross-section of the flue (3) is rectangular.
4. The device for heat preservation of coal mine shafts based on flue gas from low-concentration methane pulsating combustion according to claim 1, characterized in that: The outer side of the pulsed burner (1) is provided with a heat insulation layer.
5. The device for heat preservation of coal mine shafts based on flue gas from low-concentration methane pulsating combustion according to claim 1, characterized in that: The included angle between the axes of the pulsed burners (1) located on both sides of the flue (3) is the first included angle; The first included angle is 90°-150°.
6. The device for heat preservation of coal mine shafts based on flue gas from low-concentration methane pulsating combustion according to claim 1, characterized in that: The turbulence device (5) has a triangular prism structure.
7. The device for heat preservation of coal mine shafts based on flue gas from low-concentration methane pulsating combustion according to claim 6, characterized in that: The angle between the turbulence device (5) and the air inlet of the flue (3) is the second angle, which is 30°-60°. The width of the turbulence device (5) on the side near the outlet of the flue (3) is a, and the width of the flue (3) is b, b / 5≤a≤b / 3.