Coal mine gas fine extraction, treatment and mixing system and using method

Abstract

The invention provides a coal mine gas fine extraction, treatment and mixing system and a using method, and relates to the technical field of gas extraction treatment. The problems that the extraction rate of low-concentration gas is low, the impurity content is high, and the mixing precision is poor are solved. The system comprises a tree-shaped extraction pipe network, a spiral separation pipe, a washing device, a condenser, an adsorption tower, a membrane separation device and a dynamic and static coupling mixing system which are communicated in sequence. Directional drilling-hydraulic fracturing permeability increasing is adopted, and the low-concentration gas recovery rate is larger than or equal to 70%; multistage centrifugation, water washing, adsorption and membrane separation are combined, the removal rate of dust, H2S and CO2 is larger than or equal to 90%, and methane is purified to be larger than or equal to 95%; the static and dynamic mixing cavity is controlled by fuzzy PID closed loop, and the mixing proportion error is less than or equal to + / -1.5%. The system is modularized, explosion-proof, low in consumption and intelligent, and safe and efficient extraction and high-quality utilization of coal mine gas are achieved.

Description

Technical Field

[0001] This invention relates to the field of gas extraction and treatment technology, specifically to a refined gas extraction, treatment, and mixing system and its application method. Background Technology

[0002] In the coal mine safety production chain, gas (CH4) extraction, purification, and utilization are core links in curbing gas accidents and achieving resource recycling. With increasing mining depth and intensity, the proportion of low-concentration gas (0.15% to 1.2%) underground is rapidly rising, becoming a new "main battlefield" for gas control. However, existing technological systems are still designed based on high-concentration gas (>30%), and their adaptability to low-concentration ranges is clearly insufficient. At the extraction end, the rapid decay of negative pressure and the small extraction radius result in a gas recovery rate of less than 30% for 0.15% to 1.2% methane. At the purification end, the traditional cyclone + filter method can only remove dust with a particle size >10µm, and the removal efficiency of sulfides, water vapor and oil mist is less than 60%. The quality of gas after purification cannot meet the intake requirements of internal combustion engines or oxidation power generation. In mines, the space inside the mine is small, and it is difficult to install large-scale purification devices. At the mixing end, existing Venturi or orifice plate mixers have narrow adjustment ratios (typically 3:1), making it difficult to achieve high-precision mixing of multiple gas flow rates according to well area differences, directly restricting subsequent comprehensive utilization efficiency. A Venturi is a flow measurement and mixing system based on fluid mechanics principles. Its core structure is a pipe that first contracts and then expands (called a Venturi tube). When the fluid (gas or liquid) passes through the contraction section, the velocity increases and the static pressure decreases; in the expansion section, the velocity decreases and the pressure recovers. The pressure difference is used for flow measurement and gas mixing.

[0003] In view of the above, this application is hereby submitted. Summary of the Invention

[0004] In view of the above-mentioned problems in the existing technology, a refined coal mine gas extraction, treatment and mixing system and its usage method are provided, with the aim of solving at least one of the above problems.

[0005] The technical solution to achieve the purpose of this invention is as follows: This invention provides a refined coal mine gas extraction, treatment and mixing system, which includes an extraction pipe, a spiral separator, a water washing device and a mixing system; The outlet end of the extraction pipe is connected to the inlet end of the spiral separator, the outlet end of the spiral separator is connected to the inlet end of the washing device, and the inlet end of at least one washing device is connected to the inlet end of the mixing system. Several extraction pipes are connected in series to the gas collecting main pipe, and the outlet end of the gas collecting main pipe is connected to the inlet end of the spiral separator pipe. The spiral separator adopts a segmented structure, with the segments connected in series along the gas flow direction, and the height of its axis gradually increases to form an inclined upward spiral path; an impurity settling pipe is installed directly below the spiral separator, and the impurity settling pipe is connected to the lowest point of the bottom of the spiral separator. The washing device includes a first container and a second container, and an air bubble adjustment plate divides the washing device into the first container and the second container; a first filter screen and a second filter screen are installed in the second container; The mixing system is equipped with a static mixing chamber and a dynamic mixing chamber. The coupling between the static and dynamic mixing chambers is achieved through closed-loop feedback using an intelligent algorithm, enabling precise mixing of gas in different areas in proportion.

[0006] This invention also provides a method for using a refined coal mine gas extraction, treatment, and mixing system. This method employs a refined coal mine gas extraction, treatment, and mixing system and includes the following steps: Step 1: Drill directional boreholes in the coal seam. After hydraulic fracturing to enhance the permeability of the boreholes, install extraction pipes inside the boreholes and use the negative pressure of the extraction pump station to extract the gas. Step 2: The gas is subjected to spiral separation and water washing to remove impurities; Step 3: High-purity gas and gas from other areas enter the static mixing chamber and dynamic mixing chamber of the mixing system, respectively. The PLC controls the electric explosion-proof regulating valve based on real-time flow and concentration data to achieve precise mixing of the gas in proportion before output.

[0007] Compared with the prior art, the beneficial effects of the present invention include: (1) This invention addresses the problem of low extraction efficiency of low-concentration methane (0.15% to 1.2%) by using a "directional drilling + hydraulic fracturing" coupled permeability enhancement technology to construct a tree-like extraction network of "main hole + branch hole". This significantly improves the permeability of the coal seam and the desorption capacity of methane, increasing the recovery rate of low-concentration methane to over 70%, thus breaking through the limitation that traditional extraction technology is only applicable to high-concentration methane. (2) After passing through a spiral separation and water washing process, impurities in the gas are completely removed. Combined with modules such as condensation dehydration, adsorption desulfurization and decarbonization, and membrane separation purification, a complete gas purification chain is formed. Compared with the traditional cyclone + filter method, the present invention achieves a removal rate of over 90% for impurities such as hydrogen sulfide, oil mist, and CO2, and the outlet methane purity is ≥95%, which fully meets the intake standards of subsequent utilization equipment such as internal combustion engines and oxidation power generation. The spiral separation pipe is set inside the extraction pump station. The miniaturization of the spiral separation pipe allows the extraction pump station to be set up in the mine. The spiral separation pipe can protect the extraction pump station. (3) A "static + dynamic" dual-cavity coupled hybrid structure is adopted, and intelligent algorithms such as fuzzy PID or model predictive control (MPC) are introduced to realize real-time closed-loop control of multi-source gas flow. The mixing ratio error is ≤±1.5%, and the adjustment cycle is ≤30s. It can quickly respond to the differentiated gas concentration requirements of different modes such as power generation, heating, and emergency, and solve the problems of narrow adjustment ratio and slow response of traditional Venturi mixers. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0009] Figure 1 This is a schematic diagram of the extraction system and the separation system; Figure 2 yes Figure 1 Enlarged view of point A in the middle; Figure 3 yes Figure 2 Schematic diagram of the cross section at point BB; Figure 4 This is a schematic diagram of the water washing device; Figure 5 This is a schematic diagram of the processing device; Figure 6 yes Figure 5 This is a schematic diagram of the cross-section at point C. Figure 7 This is a schematic diagram of the drying oven. Figure 8 This is a schematic diagram of a hybrid system; Among them, 101 is the extraction pipe; 102 is the gas gathering main pipe; 111 is the first electric explosion-proof regulating valve; 112 is the second electric explosion-proof regulating valve; 113 is the third electric explosion-proof regulating valve; 114 is the fourth electric explosion-proof regulating valve; 121 is the flame arrester; 131 is the first concentration sensor; 132 is the second concentration sensor; 141 is the first gas flow sensor; and 142 is the second gas flow sensor. 2. Pumping station; 21. Spiral separator; 211. First section spiral separator; 212. Second section spiral separator; 213. Third section spiral separator; 221. First impurity settling pipe; 222. Second impurity settling pipe; 231. Fluid guide plate; 241. Settling tank; 251. Variable frequency vacuum pump; 3. Water washing device; 311. First container; 312. Second container; 321. Bubble adjusting plate; 331. First filter screen; 332. Second filter screen; 400. Condenser; 401. Condensate collection device; 500, Adsorption tower; 600, Membrane separation device; 601, Membrane; 700. Gas drying oven; 800. Mixing system; 801. Dynamic mixing chamber; 802. Stirring paddle; 803. Static mixing chamber; 804. Spiral element; 900, Filter membrane; 901, First check valve; 902, Second check valve. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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.

[0011] Therefore, the following detailed description of embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely illustrates some embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0012] It should be noted that, unless otherwise specified, the embodiments and features and technical solutions in the present invention can be combined with each other.

[0013] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0014] The present invention will be further described in detail below with reference to embodiments.

[0015] like Figures 1 to 4 As shown, the present invention provides a refined coal mine gas extraction, treatment and mixing system, which includes an extraction pipe 101, a spiral separation pipe 21, a water washing device 3 and a mixing system 800. The outlet end of the extraction pipe 101 is connected to the inlet end of the spiral separator 21, the outlet end of the spiral separator 21 is connected to the inlet end of the washing device 3, and at least one inlet end of the washing device 3 is connected to the inlet end of the mixing system 800. Several extraction pipes 101 are connected in series to the gas collecting main pipe 102, and are connected to the inlet end of the spiral separator pipe 21 through the outlet end of the gas collecting main pipe 102. The spiral separator 21 adopts a segmented structure, with the segments of the spiral separator 21 connected in series along the gas flow direction, and the height of its axis gradually increases to form an inclined upward spiral path; an impurity settling pipe is set directly below the spiral separator 21, and the impurity settling pipe is connected to the lowest point of the bottom of the spiral separator 21; the spiral separator 21 and the settling tank 241 are connected through the impurity settling pipe. An ultrasonic generator is installed on the shell of the spiral separator 21 and an ultrasonic generator is installed on the shell of the sedimentation tank 241. The washing device 3 includes a first container 311 and a second container 312. The bubble adjusting plate 321 is provided with a mesh. The bubble adjusting plate divides the washing device into the first container 311 and the second container 312. A first filter screen 331 and a second filter screen 332 are provided in the second container 312. The mixing system 800 is equipped with a static mixing chamber 803 and a dynamic mixing chamber 801. The coupling between the static mixing chamber 803 and the dynamic mixing chamber 801 is achieved through closed-loop feedback using an intelligent algorithm, enabling precise mixing of gas in different areas in proportion.

[0016] To better achieve the objectives of this invention, in some embodiments, a first electric explosion-proof regulating valve 111, a first concentration sensor 131, a first gas flow sensor 141, and a flame arrester 121 are further integrated into the extraction pipe 101. It should be noted that the methane concentration in the coal seam is in the range of 0.15% to 1.2%. The number of extraction pipes can be 800 or 2000, depending on the specific size of the collection area and the density of their distribution within that area. The collection area is the distribution area of ​​several extraction pipes in the coal seam, and this area can be dynamically increased. The outlet ends of several extraction pipes 101 are respectively connected to the inlet end of the gas gathering main pipe 102, and the extraction pipes 101 are not directly connected to each other. Figure 1 As illustrated, taking extraction pipe 101 as an example, at least the first concentration sensor 131 is installed on the gas input side of the first electric explosion-proof regulating valve 111. The first concentration sensor 131 is used to measure the gas concentration within extraction pipe 101. The first concentration sensor 131, the first gas flow sensor 141, and the first electric explosion-proof regulating valve 111 are connected to a programmable logic controller (PLC). The data from the first concentration sensor 131 can be used as a control signal for the first electric explosion-proof regulating valve 111, which controls the opening and closing of the valve. The first gas flow sensor 141 is used to measure the gas flow rate within extraction pipe 101. Operating the extraction pipe by opening and closing the electric explosion-proof regulating valve helps prevent gas explosions within the extraction pipe and allows control over the number of extraction pipes connected to the main gas collecting pipe 102.

[0017] To better achieve the objectives of this invention, in some embodiments, a second electric explosion-proof regulating valve 112, a second concentration sensor 132, and a second gas flow sensor 142 are further integrated into the gas collecting main pipe 102. Combined with... Figure 1 As shown, at least the second concentration sensor 132 is installed on the gas input side of the second electric explosion-proof regulating valve 112. The second concentration sensor 132 is used to measure the gas concentration in the gas collection main duct 102. The second concentration sensor 132, the second gas flow sensor 142, and the second electric explosion-proof regulating valve 112 are connected to a programmable logic controller (PLC). The data from the second concentration sensor 132 can be used as a control signal for the second electric explosion-proof regulating valve 112, which controls the opening and closing of the second electric explosion-proof regulating valve 112. The second gas flow sensor 142 is used to measure the gas flow rate in the gas collection main duct 102.

[0018] To better achieve the objectives of this invention, in some embodiments, preferably, the extraction pipe 101 is made of high-strength PE pipe, and the inner wall of the extraction pipe is provided with a nano-hydrophobic coating (contact angle ≥ 110°). The contact angle is a physical quantity that measures the "wetting degree" of a liquid on a solid surface. During gas extraction, water (or coal slurry) easily condenses inside the pipe. A contact angle greater than or equal to 110° means that the water will condense into beads, unable to adhere to the pipe wall, and will be carried away by the airflow, avoiding water blockage or corrosion. The small contact area between the droplets and the pipe wall reduces frictional resistance and improves extraction efficiency. Dust / coal powder is difficult to adhere to, and the water droplets can carry away impurities as they roll off. Figure 1 As shown, the directional drilling rig employs measurement while drilling (MWD). Following a three-dimensional trajectory (inclination ±15°, azimuth error ≤2°), the directional drilling rig constructs directional boreholes in the coal seam. The main borehole diameter is φ75 to 120 mm, and the borehole depth is 800 to 1500 m. Anti-collapse screens with 0.3 to 0.5 mm gaps are laid on the inner wall of the borehole. After the main borehole is completed, hydraulic fracturing equipment is used to inject 15 to 25 MPa high-pressure water (the fracturing fluid is a 0.3% guar gum aqueous solution, with a fracturing time of 4 to 6 hours) into the borehole to fracture the surrounding coal seam, creating a fracture cluster with a width of 50 to 100 μm, increasing the coal seam permeability by 3 to 5 times. Subsequently, with the main borehole as the center, φ50mm branch extraction boreholes are arranged radially at an angle of 30° to 60° and a spacing of 8 to 12m. The spacing between the main boreholes is maintained at 50 to 80m, and the extraction pipe 101 is constructed into a tree-like extraction network of "main borehole + branch borehole". Extraction pipes are installed in the main borehole and the branch borehole.

[0019] To better achieve the objectives of this invention, in some embodiments of this invention, preferably, the extraction system incorporates directional drilling-hydraulic fracturing coupling technology. Directional drilling precisely locates the gas-rich area, and hydraulic fracturing is used to construct a three-dimensional extraction network. A measurement-while-drilling (MWD) directional drilling rig is used to construct 75 to 120 mm directional boreholes along a three-dimensional trajectory (inclination ±15°, azimuth error ≤2°), with a borehole depth of 800 to 1500 m, and the inner wall is lined with 0.3 to 0.5 mm gap anti-collapse screen pipes.

[0020] To better achieve the objectives of this invention, in some embodiments of this invention, a flame arrester 121 is further installed in the extraction pipe 101 and in the gas collecting main pipe 102. Figure 1 (Not shown in the image). The flame arrester 121 uses a corrugated metal plate, wire mesh, or porous structure to divide the flame into tiny flame clusters, which are then extinguished by dissipating heat and lowering their temperature below the ignition point. The material is stainless steel (corrosion resistant) or aluminum alloy (lightweight).

[0021] To better achieve the objectives of this invention, in some embodiments, the extraction pump station 2 is further equipped with a variable frequency vacuum pump 251 to adjust the extraction negative pressure between -20 kPa and -35 kPa and dynamically control the flow rate between 5 and 50 m³ / min. For low-concentration ranges with methane concentrations below 0.5%, intermittent extraction for 10 to 15 minutes is used to improve energy efficiency. After the extraction pump station 2 is installed, it needs to undergo airtightness testing (pressure 0.5 MPa, pressure holding for 30 minutes, leakage rate ≤0.1%) and explosion-proof performance testing (certified according to GB3836 series standards); the flame arrester in the extraction pipe 101 should be cleaned regularly (cycle ≤1 month).

[0022] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figure 1 and Figure 4As shown, quick-connect couplings are installed at the inlet and outlet ends of the extraction pump station 2. The quick-connect coupling at the inlet end of the extraction pump station 2 connects to the outlet end of the gas collecting main pipe 102, and the quick-connect coupling at the outlet end of the extraction pump station 2 connects to the inlet end of the water washing device 3. A spiral separation pipe 21 connects the inlet end of the extraction pump station 2 and the variable frequency vacuum pump 251. The spiral separation pipe 21 is used to separate impurities in the gas, including particulate impurities and droplet impurities. By directly setting the spiral separation pipe 21 at the inlet front end of the vacuum pump 251, the "raw gas" extracted from the coal seam, containing a large amount of coal dust, rock powder, and water mist, undergoes multi-stage spiral centrifugal separation and gravity sedimentation before entering the vacuum pump, removing most of the abrasive particles and corrosive droplets (especially those >10µm). This greatly reduces the risk of wear, corrosion, and scaling of key components such as the vacuum pump impeller and cavity caused by impurities, significantly extends the service life of the core equipment, reduces maintenance frequency and downtime, and ensures long-term stable operation from the source of the system. The segmented, inclined, ascending structure of the spiral separator 21, while achieving efficient separation, inherently creates resistance to the gas flow due to its flow channel design. Integrating this separator into the extraction pump station 2, placing it adjacent to the vacuum pump 251, means that the vacuum pump can directly provide precisely matched negative pressure power for this separation process. The system can adjust the power of the vacuum pump 251 in real time via a frequency converter to overcome the flow resistance introduced by the separator and ensure operation within the optimal negative pressure range (-20kPa to -35kPa). This integrated design avoids pipeline pressure loss caused by remotely arranging the separation equipment, achieving precise matching and coordination between "energy consumption required for separation" and "power provided for extraction," thereby optimizing the overall energy consumption of the system while ensuring efficient separation. Integrating the spiral separator 21 as a built-in functional module of the extraction pump station 2 greatly simplifies the layout of the ground pipeline network. Traditional methods of independently installing large separation equipment occupy a large area, have complex pipeline connections, and present more leakage points. This invention integrates the separation function into the pump station, making the entire "preliminary purification-power extraction" unit highly compact and modular. This not only reduces the footprint, facilitating deployment and installation in space-constrained underground or surface sites, but also lowers the risk of gas leaks by reducing external pipeline connections, thus improving the overall safety of the system and the ease of engineering implementation. Through the slag discharge valves (such as the third electric explosion-proof regulating valve 113) and ultrasonic unblocking devices configured in the pump station, impurities can be discharged and cleaned regularly, in a controlled manner, safely. This centralized treatment mode avoids potential blockages caused by impurities transported over long distances in pipelines, as well as secondary pollution and operational complexity resulting from transfers between different equipment units, making the entire impurity treatment process more efficient, environmentally friendly, and controllable.

[0023] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figure 1The spiral separation tube 21 comprises a first spiral separation tube 211, a second spiral separation tube 212, and a third spiral separation tube 213, employing a segmented structure within. The first spiral separation tube 211, the second spiral separation tube 212, and the third spiral separation tube 213 are connected in series along the gas flow direction, with their axial height gradually increasing to form an inclined, upward spiral path. The number of spiral separation tube segments in the spiral separation tube 21 is increased according to specific separation requirements; the longer the spiral separation tube 21, the better the effect of separating impurities from the gas. Impurity-laden gas (including coal dust, water mist, etc.) enters the spiral separation tube 21 through the inlet, forming a high-speed rotating airflow guided by the spiral structure. During this high-speed rotation, due to density differences, larger impurities (solid particles and droplets) experience greater centrifugal force and are thrown towards the tube wall, achieving the separation of gas and impurities. Simultaneously, the separated impurities are facilitated to settle to the bottom of the spiral separation tube 21 under gravity.

[0024] To better achieve the purpose of the present invention, in some embodiments of the present invention, the inner wall of the spiral separation tube 21 is further provided with spiral guide ribs (not shown in the figure), the spiral direction of which is consistent with the rotation direction of the airflow, in order to enhance the rotation intensity of the airflow, thereby improving the centrifugal separation effect.

[0025] To better achieve the purpose of the present invention, in some embodiments of the present invention, a first impurity settling pipe 221 and a second impurity settling pipe 222 are further provided directly below the spiral separation pipe 21. The first impurity settling pipe 221 and the second impurity settling pipe 222 are connected at the lowest point of the bottom of the spiral separation pipe 21, so that impurities can settle in the first impurity settling pipe 221 and the second impurity settling pipe 222 under the action of gravity.

[0026] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figures 1 to 3As shown, at the connection between the spiral separator 21 and the first impurity settling pipe 221, a fluid guide plate 231 is provided at the top of the inner wall of the spiral separator 21. The windward side of the fluid guide plate 231 has an inwardly concave curved surface, while the windward side has an outwardly convex curved surface, and one-third to one-half of the length of the fluid guide plate 231 extends into the inlet end of the first impurity settling pipe 221. This design is beneficial for utilizing the kinetic energy of gas movement to smoothly guide the gas flow to the inlet end of the first impurity settling pipe 221, while enhancing the centrifugal separation effect and promoting the settling of impurities under gravity. The fluid guide plate 231 effectively prevents impurities from flowing back into the spiral separator 21. For example, when the first impurity settling pipe 221 is located at the connection between the second spiral separator 212 and the third spiral separator 213, the fluid guide plate 231 effectively prevents impurities in the third spiral separator 213 from flowing to the second spiral separator 212, instead guiding the impurities to the inlet end of the first impurity settling pipe 221, causing the impurities to settle in the first impurity settling pipe 221. Similarly, at the connection between the spiral separator 21 and the second impurity settling pipe 222, a similar fluid guide plate 231 is also provided at the top of the inner wall of the spiral separator 21 to guide the gas flow to the inlet end of the second impurity settling pipe 222. The impurity settling pipes include the first impurity settling pipe 221 and the second impurity settling pipe 222, and the number of impurity settling pipes is determined according to specific circumstances. The concave windward side and the convex windward side form a streamlined structure, reducing airflow resistance and enhancing centrifugal force, making it easier for impurities to be thrown against the pipe wall and settle. The plate extends into the settling pipe inlet, effectively blocking the reverse flow of impurities and ensuring that the separated impurities enter the settling tank in time to avoid secondary pollution. Combined with the segmented structure and inclined upward path of the spiral separation pipe, the overall impurity removal rate is improved, providing a cleaner gas source for subsequent water washing and purification processes.

[0027] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figure 1 As shown, the spiral separation pipe 21 and the sedimentation tank 241 are connected through the first impurity settling pipe 221, and the spiral separation pipe 21 and the sedimentation tank 241 are connected through the second impurity settling pipe 222; the gas moves in the spiral separation pipe 21, and the gas and impurities are separated under the action of centrifugal force, and the impurities settle into the sedimentation tank 241 through the first impurity settling pipe 221 and the second impurity settling pipe 222.

[0028] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figure 1 As shown, the sedimentation tank 241 discharges impurities through the third electric explosion-proof regulating valve 113.

[0029] To better achieve the objectives of this invention, in some embodiments, an ultrasonic generator (not shown in the figure) is further provided on the shell of the spiral separator 21 and on the shell of the settling tank 241. The number and position of the ultrasonic generators are determined according to specific circumstances. It should be noted that during normal operation of the spiral separator 21 or during the removal of impurities, the ultrasonic generator causes the spiral separator 21 to vibrate at high frequency, causing particles and droplets of impurities accumulated on the inner wall of the spiral separator 21 to continuously fall off. During the discharge of impurities from the settling tank 241, the ultrasonic generator on its shell is activated.

[0030] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figure 4 As shown, the washing device 3 includes a first container 311 and a second container 312. A bubble adjusting plate 321 has mesh openings, dividing the washing device 3 into the first container 311 and the second container 312 (including the space for the pipe connection within the washing device 3). The first container 311 and the second container 312 are connected through the mesh openings on the bubble adjusting plate 321. A first filter screen 331 and a second filter screen 332 are installed in the second container 312. In operation, the water level in the second container 312 exceeds the height of the first filter screen 331 but does not exceed the height of the second filter screen 332; that is, the first filter screen 331 is below the water surface, and the second filter screen 332 is above the water surface. A fourth electric explosion-proof regulating valve 114 is installed at the bottom of the first container 311 for discharging or injecting water into the first container 311. It should be noted that the mesh openings on the bubble adjusting plate 321 perform initial segmentation of the gas bubbles, facilitating thorough mixing of the gas and water and removing impurities from the gas. The first filter screen 331 has a multi-layered structure, such as 3 or 5 layers. The mesh openings between the layers are staggered to further separate gas bubbles, facilitating thorough mixing of gas and water and removing impurities from the gas. The material of each filter layer can be chosen from various options, such as stainless steel with a mesh size of 50μm or 40μm; sintered metal filter elements with a mesh size of 20μm or 15μm; or fiber filter layers with a mesh size of 5μm or 4μm. The second filter screen 332 is used to remove moisture carried by the gas.

[0031] To better achieve the objectives of this invention, in some embodiments of this invention, preferably, in combination with... Figure 5As shown, the condenser 400 is equipped with a condensate collection device 401. In the condensation and dehydration process, the shell-and-tube condenser 400 (heat exchange area 20 to 30 m²) cools the gas to ≤10°C using circulating water at 5 to 10°C. Simultaneously, a gas-liquid separator removes the condensate, which is then discharged through the condensate collection device 401, with an outlet moisture content ≤5 g / m³. The outlet end of the water washing device 3 is connected to the inlet end of the condenser 400.

[0032] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figure 5 As shown, the adsorption tower 500 is filled with modified activated carbon. In the desulfurization stage, the H2S removal rate is ≥99%, and the outlet H2S is ≤20ppm; in the decarbonization stage, the dynamic adsorption capacity for CO2 is ≥20mg / g, significantly reducing acidic components; in the regeneration stage, after adsorption saturation, the activated carbon is completely regenerated by purging with closed-loop hot nitrogen at 5–10m³ / h and 120℃ for 2h, with a cycle life ≥5000 times. After this stage of treatment, impurities (H2S, CO2) in the gas are deeply removed, providing clean and stable feed gas for subsequent high-value utilization.

[0033] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figure 5 and Figure 6 As shown, the membrane separation device 600 includes a membrane 601, which is a spiral wound hollow fiber membrane module. The adsorption-purified methane enters the spiral wound hollow fiber membrane module (pore size 0.1 to 0.5 nm) at a pressure of 0.5 to 1.0 MPa. Utilizing the molecular-level sieving effect, the module purifies methane to ≥95% in one step (adjustable online), while simultaneously maintaining the rejection rate of impurities such as CO2 and N2 at ≥90%, providing high-purity, low-fluctuation feed gas for downstream applications.

[0034] To better achieve the objectives of this invention, in some embodiments of this invention, preferably, in combination with... Figure 7 As shown, the inlet end of the gas drying box 700 is connected to the outlet end of the membrane separation device 600, and a first check valve 901 is provided on the inlet section of the gas drying box 700; the gas drying box 700 is filled with a desiccant (such as silica gel or molecular sieve) to remove moisture from the gas and avoid affecting the mixing uniformity.

[0035] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figure 8As shown, the mixing system 800 includes a dynamic mixing chamber 801 and a static mixing chamber 803. The static mixing chamber 803 is equipped with a spiral element 804, and the dynamic mixing chamber 801 is equipped with a stirring paddle 802. The inlet end of the mixing system 800 is connected to the outlet ends of several gas drying chambers 700, such as two or three. It should be noted that the static mixing chamber 803 and the dynamic mixing chamber 801 are two spaces connected in series. The spiral element 804 in the static mixing chamber 803 causes the airflow to be divided, rotated, and then recombined, achieving initial homogenization. The dynamic mixing chamber 801 is equipped with adjustable components, which, by changing the rotation speed or angle of the stirring paddle 802 in real time, perform secondary forced disturbance on the airflow to further eliminate the concentration gradient. The static mixing chamber 803 and the dynamic mixing chamber 801 are not simply connected in series, but are coupled through closed-loop feedback. A high-frequency CH4 concentration sensor and flow sensor at the outlet send real-time data to the controller. The controller dynamically adjusts the disturbance intensity or blade angle of the dynamic chamber according to the set target value, ensuring that the outlet concentration and flow rate remain within the allowable error range. The entire coupling process, driven by intelligent algorithms (such as Model Predictive Control (MPC), fuzzy PID, or deep learning predictive models), possesses self-learning and self-correction capabilities: it can memorize the gas quality and flow characteristics of different well areas and automatically match the optimal disturbance strategy; when encountering sudden changes in operating conditions (such as a sharp drop in extracted gas concentration), it completes parameter retuning within seconds, ensuring that the mixing ratio error is ≤±2%. When approaching the limit, the system conversely fine-tunes the valve or orifice opening before the static chamber, achieving coordinated "coarse adjustment—fine adjustment." By using a static mixing chamber for coarse mixing and a dynamic mixing chamber for fine mixing, and then coupling the two in a closed loop using real-time sensing and intelligent algorithms, high-precision, wide-range, and adaptive mixing of multi-source low-concentration gas is achieved.

[0036] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figure 8 As shown, the gas first enters the static mixing chamber 803, which contains a spiral element 804 with a pitch of 100-150 mm and an inclination angle of 45° (the specific number is selected according to the actual situation of the mining area). Figure 8The mixture is initially mixed using two helical elements (in the middle section), forming a turbulent initial mixing flow (uniformity ≥85%). The initially mixed gas enters the dynamic mixing chamber 801, which is equipped with a three-bladed agitator 802. The three blades have a multi-layered staggered structure (rotation speed 150~350rpm, diameter 0.6 times the chamber diameter) and a flow guide baffle (angle 25°~35°) to further stir and mix the gas, achieving a final mixing uniformity ≥98%. During the mixing process, an ultrasonic flow sensor (accuracy ±1%) and an infrared concentration sensor (resolution 0.1%) at the inlet monitor the flow rate and concentration of each gas source in real time and transmit the data to the PLC explosion-proof control box. The PLC explosion-proof control box calculates the input ratio of gas in each zone based on a fuzzy PID algorithm, and drives the electric explosion-proof regulating valve (response time ≤ 2s) in real time to adjust the flow rate, achieving precise control with a mixing ratio error of ≤ ±1.5% to meet the concentration requirements of different modes such as power generation (CH4 ≥ 30%, adjustment cycle ≤ 30s), heating (15%~25%, overshoot ≤ 5%), and emergency (≤ 5%). The measurement and control unit integrates an ultrasonic flow sensor (accuracy ±1%) and an infrared concentration sensor (resolution 0.1%), and adjusts the electric explosion-proof regulating valve (referred to as "explosion-proof valve") in real time based on the fuzzy PID algorithm, with a response time ≤ 2s.

[0037] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figure 8 As shown, infrared concentration sensors (resolution 0.1%) are installed at the inlet and outlet of the mixing chamber to form a dual closed-loop concentration monitoring system, which calculates the mixing error in real time and dynamically adjusts the valve opening. The mixing chamber includes a static mixing chamber 803 and a dynamic mixing chamber 801. A first check valve 901 and an electric explosion-proof regulating valve are installed on the inlet side of the static mixing chamber 803. A second check valve 902 and an electric explosion-proof regulating valve are installed on the outlet side of the dynamic mixing chamber 801.

[0038] To better achieve the objectives of this invention, in some embodiments of this invention, further, in conjunction with Figure 8 As shown, a filter membrane 900 assembly (mesh diameter ≤ 5 μm) is installed at the outlet of the mixing chamber to filter fine particles in the mixed gas.

[0039] To better achieve the objectives of this invention, in some embodiments of this invention, preferably, multiple air intake pipes are provided at the inlet of the mixing chamber (in... Figure 8 (Not shown in the image) When the concentration sensor at the inlet of the mixing chamber detects that the gas concentration deviates from the set value, it is first coarsely adjusted through the first air inlet pipe (air) or the second air inlet pipe (high concentration gas), and then finely adjusted through the speed of the stirring paddle in the dynamic mixing chamber (adjustment cycle ≤ 10s). Finally, the outlet concentration sensor confirms that the standard has been met and then opens the outlet valve to achieve precise control of the mixing ratio error ≤ ±1.5%.

[0040] To better achieve the purpose of the present invention, in some embodiments of the present invention, when the mixing concentration exceeds a preset range (e.g., CH4 < 30% or > 50% in power generation mode), the audible and visual alarm device is automatically triggered to cut off the intake valve, and the nitrogen purging device is started at the same time.

[0041] It should be noted that flame arresters are installed at the inlet and outlet of the equipment for extracting, processing, and mixing methane gas to prevent backfire from causing an explosion; check valves are added at all pipeline connections to prevent gas backflow. For example, at key nodes such as the outlet of the extraction pump station, the inlet and outlet of the cyclone separator, and the inlet of the mixing chamber. Intelligent sensor networks and PLC control systems are integrated into the equipment for extracting, processing, and mixing methane gas to achieve real-time monitoring and automated control of parameters throughout the entire process.

[0042] To better achieve the objectives of this invention, in some embodiments of this invention, the hybrid system further includes a preset multi-mode control algorithm: a power generation mode with a fast response adjustment cycle of ≤30s, a heating mode with a stable control overshoot of ≤5%, and an emergency mode that automatically matches a safe concentration to prevent explosion risks.

[0043] This invention also provides a method for using a refined coal mine gas extraction, treatment, and mixing system. This method employs a refined coal mine gas extraction, treatment, and mixing system and includes the following steps: Step 1: Directional drilling is performed in the coal seam. After hydraulic fracturing to enhance permeability, extraction pipes are installed inside the boreholes, and the gas is extracted using the negative pressure of the extraction pump station. Step S11: Directional drilling is carried out using an MWD directional drilling rig along a three-dimensional trajectory (inclination ±15°, azimuth error ≤2°) to construct the main borehole (φ75-120mm, borehole depth 800-1500m) in the coal seam. The inner wall is lined with 0.3-0.5mm gap anti-collapse screen pipes. Subsequently, branch boreholes (φ50mm) are constructed at a radial angle of 30°-60° and a spacing of 8-12m, forming a tree-like network of "main borehole + branch borehole". Step S12: Inject 15-25MPa high-pressure fracturing fluid (0.3% guar gum aqueous solution, broken up in 4-6 hours) into the borehole using hydraulic fracturing equipment to form a 50-100μm fracture group in the coal seam, thereby increasing the coal seam permeability by 3-5 times. Step S13: Install a high-strength PE extraction pipe in each borehole, with its inner wall coated with a nano hydrophobic coating (contact angle ≥110°), and install a flame arrester, an electric explosion-proof regulating valve, a concentration sensor, and a gas flow sensor in sequence at the borehole opening. Step S14: All extraction pipes are connected to the variable frequency vacuum extraction pump station via the gas collection main pipe; the PLC controls the number of electric explosion-proof regulating valves to open and close in real time according to the concentration / flow of each pipe, so that the negative pressure in the pipe is maintained between -20kPa and -35kPa; when the gas concentration is <0.5%, the intermittent extraction mode of 10-15min is automatically switched.

[0044] Step 2: The gas is subjected to spiral separation and water washing to remove impurities, and the gas after impurity removal is subjected to desulfurization, decarbonization, methane enrichment and deep water removal treatment. The gas collected by the extraction system usually contains impurities such as coal dust, water mist, oil droplets, hydrogen sulfide (H2S), and carbon dioxide (CO2). It needs to undergo multi-stage treatment to achieve efficient purification and methane enrichment, ensuring that the subsequent mixing and utilization process is safe, stable, and efficient. S21: The gas first enters the spiral separator 21, which has a multi-segment structure (including the first spiral separator 211, the second spiral separator 212, and the third spiral separator 213). The height of the spiral separator gradually increases along the airflow direction axis, forming an inclined upward spiral path. During the high-speed rotating flow, denser particulate impurities and droplets are thrown towards the pipe wall under centrifugal force and settle to the lowest point at the bottom of the pipe under gravity.

[0045] The separated impurities are discharged through the first impurity settling pipe 221 and the second impurity settling pipe 222 located at the bottom of the spiral separator, and collected in the settling tank 241 for centralized treatment. The settling tank is equipped with a third electric explosion-proof regulating valve 113, which can automatically discharge slag periodically, and is also equipped with an ultrasonic generator to assist in cleaning attached impurities and prevent clogging.

[0046] Preferably, the inner wall of the spiral separator is provided with spiral guide ribs, the direction of which is consistent with the airflow, to enhance the rotation intensity and improve the separation efficiency.

[0047] S22: After preliminary impurity removal, the gas enters the water washing device 3, which is divided into a first container 311 and a second container 312 by a bubble adjustment plate 321. The gas passes through the washing liquid in the form of bubbles, effectively removing residual dust, water-soluble and oil mist impurities.

[0048] The second container 312 is equipped with a first filter screen 331 and a second filter screen 332 to trap droplets and particles carried by bubbles, thereby improving gas-liquid separation efficiency. A condenser 400 is installed at the outlet of the water washing device. Circulating cooling water at 5~10℃ cools the gas to ≤10℃ for further condensation and dehydration. The condensate is discharged through a condensate collection device 401, ensuring that the outlet moisture content is ≤5g / m³.

[0049] S23: The gas, after condensation and dehydration, enters the adsorption tower 500, which is filled with modified activated carbon, possessing high selective adsorption capacity. Desulfurization stage: H2S removal rate ≥99%, outlet concentration ≤20ppm; Decarbonization stage: CO2 dynamic adsorption capacity ≥20mg / g, significantly reducing acid gas content; Regeneration stage: After adsorption saturation, the activated carbon is purged with 120℃ closed-loop hot nitrogen (5–10 m³ / h) for 2 hours to achieve complete regeneration, with a cycle life of ≥5000 cycles.

[0050] This step effectively removes acidic components from the gas, providing a clean gas source for subsequent membrane separation.

[0051] S24: The purified gas enters the membrane separation unit 600 under a pressure of 0.5 to 1.0 MPa. This unit uses a spiral wound hollow fiber membrane module 601 with a membrane pore size of 0.1 to 0.5 nm, achieving gas separation based on the molecular-level sieving effect. Methane (CH4) permeates through a membrane module, is purified to ≥95%, and outputs as high-purity gas; Impurities such as CO2 and N2 are retained with a retention rate of ≥90%, and are discharged through a bypass or recycled.

[0052] Membrane separation processes do not require chemical reagents and have advantages such as low energy consumption, no pollution, and continuous operation.

[0053] S25: High-purity gas then enters the gas drying oven 700, which is filled with silica gel or molecular sieve desiccant to further remove residual moisture and prevent water vapor from affecting concentration stability or equipment corrosion during subsequent mixing.

[0054] The drying chamber inlet is equipped with a first check valve 901 to prevent gas backflow; the desiccant is recommended to be replaced when the humidity is ≥50%RH to ensure the outlet gas.

[0055] Step 3: High-purity gas and gas from other areas enter the static mixing chamber and dynamic mixing chamber of the mixing system, respectively. The PLC controls the electric explosion-proof regulating valve based on real-time flow and concentration data to achieve precise mixing of the gas in proportion before output. Step S31: After the system is powered on, perform an airtightness test (hold pressure at 0.5MPa for 30 minutes, leakage rate ≤0.1%) and an explosion-proof self-test.

[0056] In step S32, high-purity gas and other regional gas (concentration and flow rate have been measured online) enter the static mixing chamber 803 through the first check valve 901. The built-in spiral element 804 (pitch 100-150mm, inclination angle 45°) generates turbulence, with an initial uniformity ≥85%. The initially mixed gas enters the dynamic mixing chamber 801, where the three-bladed agitator 802 rotates at 150-350rpm (diameter 0.6 times that of the chamber), further forcibly agitating the gas with the guide baffle, achieving a uniformity ≥98%.

[0057] Step S33, closed-loop control: the infrared concentration sensor (resolution 0.1%) and ultrasonic flow sensor (accuracy ±1%) at the inlet / outlet of the mixing chamber collect data in real time. The PLC explosion-proof control box calculates the gas input ratio of each area based on the fuzzy PID algorithm and adjusts the electric explosion-proof regulating valve within ≤2s to make the outlet concentration error ≤±1.5%.

[0058] It should be noted that technical features that are not fully explained will be addressed using conventional technical methods.

[0059] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described herein. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the specific embodiments described above. Therefore, any modifications or equivalent substitutions to the present invention, as well as all technical solutions and improvements that do not depart from the spirit and scope of the invention, are covered within the scope of the claims of the present invention.

Claims

1. A refined coal mine gas extraction, treatment, and mixing system, comprising an extraction pipe (101), a spiral separator (21), a water washing device (3), and a mixing system (800); characterized in that, The outlet end of the extraction pipe (101) is connected to the inlet end of the spiral separator (21), the outlet end of the spiral separator (21) is connected to the inlet end of the washing device (3), and the inlet end of at least one washing device (3) is connected to the inlet end of the mixing system (800). Several extraction pipes (101) are connected in series to the gas collecting main pipe (102), and are connected to the inlet end of the spiral separator (21) through the outlet end of the gas collecting main pipe (102); The spiral separator (21) adopts a segmented structure. The segmented spiral separators (21) are connected in series along the gas flow direction, and their axial height gradually increases to form an inclined spiral path. An impurity settling pipe is set directly below the spiral separator (21), and the impurity settling pipe is connected to the lowest point of the bottom of the spiral separator (21). The washing device (3) includes a first container (311) and a second container (312). The bubble adjustment plate divides the washing device into the first container (311) and the second container (312). A first filter screen (331) and a second filter screen (332) are provided in the second container (312). The mixing system (800) is equipped with a static mixing chamber (803) and a dynamic mixing chamber (801). The coupling between the static mixing chamber (803) and the dynamic mixing chamber (801) is achieved through closed-loop feedback by an intelligent algorithm, so as to achieve precise mixing of gas in different areas in proportion.

2. The coal mine gas fine extraction, treatment and mixing system according to claim 1, characterized in that, The extraction pipe (101) is made of high-strength PE pipe, and the inner wall of the extraction pipe is provided with a nano-hydrophobic coating.

3. The coal mine gas fine extraction, treatment and mixing system according to claim 1, characterized in that, The inlet end of the extraction pump station (2) and the variable frequency vacuum pump (251) are connected by a spiral separation pipe (21); quick connectors are set at the inlet end and the outlet end of the extraction pump station (2); the quick connector at the inlet end of the extraction pump station (2) is connected to the outlet end of the gas collecting main pipe (102), and the quick connector at the outlet end of the extraction pump station (2) is connected to the inlet end of the water washing device (3).

4. The refined coal mine gas extraction, treatment, and mixing system according to claim 1, characterized in that, The inner wall of the spiral separator (21) is provided with spiral guide ribs, and the spiral direction is consistent with the airflow rotation direction.

5. A refined coal mine gas extraction, treatment, and mixing system according to claim 1, characterized in that, A first impurity settling tube (221) and a second impurity settling tube (222) are arranged directly below the spiral separator (21).

6. A refined coal mine gas extraction, treatment, and mixing system according to claim 5, characterized in that, The spiral separation pipe (21) and the sedimentation tank (241) are connected through the first impurity settling pipe (221), and the spiral separation pipe (21) and the sedimentation tank (241) are connected through the second impurity settling pipe (222).

7. A refined coal mine gas extraction, treatment, and mixing system according to claim 1 or 5, characterized in that, At the connection between the spiral separator (21) and the first impurity settling pipe (221), a fluid guide plate (231) is provided at the top of the inner wall of the spiral separator (21). The fluid guide plate (231) guides the gas flow to the inlet end of the first impurity settling pipe (221).

8. A method for using a refined coal mine gas extraction, treatment, and mixing system, comprising the refined coal mine gas extraction, treatment, and mixing system as described in any one of claims 1 to 7, characterized in that, It includes the following steps: Step 1: Drill directional boreholes in the coal seam. After hydraulic fracturing to enhance the permeability of the boreholes, install extraction pipes inside the boreholes and use the negative pressure of the extraction pump station to extract the gas. Step 2: The gas is subjected to spiral separation and water washing to remove impurities; Step 3: High-purity gas and gas from other areas enter the static mixing chamber and dynamic mixing chamber of the mixing system, respectively. The PLC controls the electric explosion-proof regulating valve based on real-time flow and concentration data to achieve precise mixing of the gas in proportion before output.

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