Defoaming device for air screw foam drilling of underground coal mine gas extraction hole

Abstract

The invention provides a defoaming device for air screw foam drilling of an underground coal mine gas extraction hole, which comprises a vertically arranged foam inlet pipe, the bottom of the foam inlet pipe is hermetically connected with an inlet pipe fixing flange, a first-stage upper flange is arranged at the bottom of the inlet pipe fixing flange, the first-stage upper flange is connected with a first-stage cyclone pipe shoulder, and a second-stage cyclone pipe shoulder is arranged at the bottom of the first-stage cyclone pipe shoulder. The first-stage cyclone pipe is connected with a first-stage connecting pipe, a flange plate of a first-stage upper flange is further connected with one end of a first-stage air inlet pipe outer cylinder, a first-stage lower flange is arranged at the other end of the first-stage air inlet pipe outer cylinder, a flange plate of the first-stage lower flange is further connected with the first-stage air inlet pipe outer cylinder, the first-stage lower flange is further connected with a first-stage connecting pipe, and the first-stage lower flange is communicated with a tail pipe; according to the device, multiple principles of negative pressure, centrifugation, shearing and inflation saturation are used for cooperative defoaming, the defoaming efficiency can be improved, the foaming capacity of the foam base fluid cannot be affected, and the problems that foam is not eliminated in time, and the recycling and reusing rate of the foam base fluid is low are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal and gas management and coalbed methane development, relates to drilling and hole forming for gas extraction drilling in coal mines, and specifically relates to a defoaming device for air screw foam drilling of gas extraction holes in coal mines. Background Art

[0002] According to statistics, given the complexity of my country's coal seam geological conditions, soft coal seams with a firmness coefficient of f<1 account for a significant proportion of the total, accounting for more than 50%. Drilling holes in soft coal seams has always been a major problem that has plagued the coal industry. During the drilling process, it is easy to cause hole collapse and drill jamming accidents, resulting in low drilling rate and the drilling depth not reaching the designed hole depth. At present, medium-pressure air drilling technology in coal mines has become the main technology for drilling holes in soft coal seams. This technology is superior in terms of removing coal powder and rock cuttings. At the same time, this technology has little scouring effect on the hole wall of soft coal seams, significantly reducing the risk of hole wall collapse. However, it is difficult to deal with dust pollution at the hole mouth during the construction of this technology, and it is easy to pose a threat to the health and safety of construction workers in the limited space of the tunnel. Foam drilling technology uses foam fluid as the flushing medium. Due to the good rock carrying performance, slow circulation flow rate and weak scouring effect on the hole wall of the foam fluid, it has been widely used in geological drilling and oil drilling. Therefore, when drilling gas extraction holes in soft coal seams, the use of foam flushing fluid drilling can not only quickly form holes but also maintain a high gas permeability, and at the same time can well solve the problem of dust pollution at the hole mouth. However, in the drilling process of soft coal seams, foam drilling technology has not been widely used, mainly due to the insufficient reuse rate of foam and the untimely elimination of foam. At present, the more commonly used defoaming methods are natural defoaming method and defoaming agent defoaming method. The former has a large slurry pool and a long defoaming cycle; the latter is difficult to re-foam and recycle the foam base liquid, and a new foam base liquid needs to be prepared for each cycle, resulting in increased drilling costs. Therefore, in order to promote the large-scale application and development of foam drilling technology in coal mines, it is urgent to develop an efficient defoaming device that adapts to the working conditions of coal mines, so as to improve the defoaming efficiency, reduce the cost of using foam flushing fluid, and promote the further development of foam drilling technology in the field of coal mining. Summary of the invention

[0003] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a defoaming device for air screw foam drilling of gas extraction holes in underground coal mines, so as to solve the technical problem that when foam drilling is used for gas extraction holes in soft coal seams in the prior art, the efficiency of eliminating returned foam and the reuse rate of foam base liquid need to be further improved.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0005] An anti-foaming device for air screw foam drilling in gas drainage holes in underground coal mines, comprising a vertically arranged foam inlet pipe, the bottom of the foam inlet pipe is fixedly connected to one end of a fixed flange of the inlet pipe, and a first-stage air inlet anti-foaming unit is arranged at the other end of the fixed flange of the inlet pipe.

[0006] The first-stage air inlet anti-foaming unit includes a first-stage upper flange, one end of the first-stage upper flange is hermetically connected to the other end of the fixed flange of the inlet pipe, the other end of the first-stage upper flange is shoulder-connected to one end of a coaxial first-stage swirl pipe, the other end of the first-stage swirl pipe is hermetically connected to one end of a coaxial first-stage connecting pipe, and a first-stage upper flange annular groove is further arranged on the lower surface of the flange plate of the first-stage upper flange. The other end of the first-stage upper flange is also fixedly and hermetically connected to one end of a coaxial first-stage air inlet outer cylinder through the first-stage upper flange annular groove. The first-stage air inlet outer cylinder is coaxially sleeved outside the first-stage swirl pipe and the first-stage connecting pipe. The other end of the first-stage air inlet outer cylinder is coaxially provided with a first-stage lower flange, and a first-stage lower flange annular groove is arranged on the upper surface of the flange plate of the first-stage lower flange. One end of the first-stage lower flange is fixedly and hermetically connected to the other end of the first-stage air inlet outer cylinder through the first-stage lower flange annular groove, and one end of the first-stage lower flange is also shoulder-connected to the other end of the coaxial first-stage connecting pipe.

[0007] A first-stage air inlet is transversely arranged on the side wall of the first-stage air inlet outer cylinder. The annular cavity formed by the inside of the first-stage air inlet outer cylinder and the outside of the first-stage swirl pipe, and the inside of the first-stage air inlet outer cylinder and the outside of the first-stage connecting pipe is a first-stage air distribution space.

[0008] A plurality of first-stage swirl pipe tangential inlet channels are evenly arranged along the circumferential direction on the side wall of the first-stage swirl pipe. Each first-stage swirl pipe tangential inlet channel is tangent to the side wall of the first-stage swirl pipe. The channel connecting the first-stage air inlet, the first-stage air distribution space and the first-stage swirl pipe tangential inlet channel is a first-stage air distribution channel.

[0009] The cavity at the center inside the foam inlet pipe is a foam suction chamber.

[0010] The cavity at the center inside the first-stage swirl pipe and the cavity at the center inside the first-stage connecting pipe form a first-stage anti-foaming chamber, and the first-stage anti-foaming chamber is communicated with the foam suction chamber.

[0011] The present invention also has the following technical features:

[0012] Preferably, the shape of the cavity at the center inside the first-stage swirl pipe is a straight cylinder shape.

[0013] The shape of the cavity at the center inside the first-stage connecting pipe is also a straight cylinder shape.

[0014] The diameter of the first-stage anti-foaming chamber is 60 - 100 mm.

[0015] The multiple first-stage cyclone tube tangential inlet channels are uniformly arranged along the circumferential direction of the first-stage cyclone tube on the same horizontal line. Each first-stage cyclone tube tangential inlet channel is the same and has a diameter of 8 - 15 mm. The setting direction of each first-stage cyclone tube tangential inlet channel is obliquely downward, and the central axis inside each first-stage cyclone tube tangential inlet channel forms an angle θ with the horizontal direction, and 0° < θ ≤ 30°.

[0016] Preferably, the bottom of the first-stage cyclone tube is arranged in a boss shape along the circumferential direction, and the top of the first-stage connecting pipe is arranged in a concave shape along the circumferential direction. The concave part of the first-stage connecting pipe can be hermetically connected to the convex part of the first-stage cyclone tube.

[0017] Preferably, a first sealing ring is coaxially arranged at the connection between the inlet pipe fixed flange and the first-stage upper flange.

[0018] Preferably, the other end of the first-stage lower flange is hermetically connected to one end of the second-stage air inlet defoaming unit, the other end of the second-stage air inlet defoaming unit is hermetically connected to one end of the tail pipe fixed flange, and the other end of the tail pipe fixed flange is fixedly connected to one end of the coaxially arranged tail pipe.

[0019] The structure of the second-stage air inlet defoaming unit is the same as that of the first-stage air inlet defoaming unit.

[0020] Specifically, the second-stage air inlet defoaming unit includes a second-stage upper flange, which is located at the bottom of the first-stage lower flange and is coaxially arranged. One end of the second-stage upper flange is hermetically connected to the other end of the first-stage lower flange.

[0021] The second-stage air inlet defoaming unit further includes a second-stage lower flange, which is located at the bottom of the second-stage upper flange and is coaxially arranged. A tail pipe fixed flange is also coaxially arranged at the bottom of the second-stage lower flange. One end of the second-stage lower flange is fixedly connected to the tail pipe fixed flange, and the other end of the tail pipe fixed flange is fixedly connected to one end of the coaxially arranged tail pipe. One end of the tail pipe is communicated with the outside.

[0022] Specifically, the second-stage air inlet defoaming unit further includes a second-stage cyclone tube tangential inlet channel, and the structure of the second-stage cyclone tube tangential inlet channel is the same as that of the first-stage cyclone tube tangential inlet channel.

[0023] The distance between the center point at the outlet of the second-stage cyclone tube tangential inlet channel and the center point at the outlet of the first-stage cyclone tube tangential inlet channel is 100 - 200 mm.

[0024] Preferably, a second sealing ring is coaxially arranged at the connection between the first-stage lower flange and the second-stage air inlet defoaming unit.

[0025] A third sealing ring is coaxially arranged at the connection between the second-stage air inlet defoaming unit and the tail pipe fixed flange.

[0026] Compared with the prior art, the present invention has the following technical effects:

[0027] (Ⅰ) The device in the present invention utilizes multiple principles such as negative pressure, centrifugation, shearing, and aeration saturation to cooperate in defoaming. It can not only improve the defoaming efficiency, increase the foam treatment capacity, but also not affect the foaming ability of the foam base liquid, reduce the cost of foam drilling, solve the problems of untimely foam elimination and low recycling rate of the foam base liquid, and promote the application and development of the foam drilling technology for gas drainage holes in coal mines.

[0028] (Ⅱ) The device in the present invention is connected by flanges or shoulders, which facilitates the replacement and maintenance of components in severely worn parts. Description of the Drawings

[0029] Figure 1 is a cross-sectional view of the entire device in the present invention.

[0030] Figure 2(a) is a three-dimensional schematic diagram of the primary cyclone tube in the present invention.

[0031] Figure 2(b) is Figure 1 the bottom view schematic diagram of the primary cyclone tube in

[0032] Figure 2(c) is Figure 1 the cross-sectional view of the primary cyclone tube in

[0033] Figure 3 is Figure 1 the cross-sectional view of the primary connecting tube in

[0034] Figure 4(a) is the pressure distribution curve on the central axis of the entire device under different air volumes in the present invention.

[0035] Figure 4(b) is the relationship diagram between the maximum negative pressure value on the central axis of the entire device and different air volumes in the present invention.

[0036] Figure 4(c) is the relationship diagram between the average negative pressure value on the central axis of the entire device and different air volumes in the present invention.

[0037] Figure 4(d) is the relationship diagram between the approximate flow rate at the foam inlet and different air volumes in the present invention.

[0038] The meanings of the various reference numerals in the figure are as follows: 1 - foam inlet pipe, 2 - inlet pipe fixed flange, 3 - primary air intake defoaming unit, 4 - tail pipe, 5 - foam suction chamber, 6 - first sealing ring, 7 - secondary air intake defoaming unit, 8 - tail pipe fixed flange, 10 - second sealing ring, 11 - third sealing ring.

[0039] 301 - Upper flange of the first stage, 302 - Swirl pipe of the first stage, 303 - Connecting pipe of the first stage, 304 - Annular groove of the upper flange of the first stage, 305 - Outer cylinder of the intake pipe of the first stage, 306 - Lower flange of the first stage, 307 - Annular groove of the lower flange of the first stage, 308 - Gas distribution channel of the first stage, 309 - Defoaming chamber of the first stage.

[0040] 701 - Upper flange of the second stage, 702 - Lower flange of the second stage, 703 - Tangential inlet channel of the swirl pipe of the second stage.

[0041] 30801 - Intake pipe of the first stage, 30802 - Gas distribution space of the first stage, 30803 - Tangential inlet channel of the swirl pipe of the first stage.

[0042] The following further elaborates on the specific content of the present invention in conjunction with the accompanying drawings and embodiments. Specific embodiments

[0043] It should be noted that all the components and materials in the present invention, unless otherwise specified, are all components and materials known in the prior art. For example, the connecting pipe uses a known connecting pipe, the flange uses a known flange, and the gasket uses a known gasket.

[0044] In the present invention, the coordinate system OXYZ is a known three - dimensional rectangular coordinate system; the X - axis is horizontal, and its direction is to the right; the Y - axis is vertical, and its direction is forward; the Z - axis is vertical, and its direction is upward.

[0045] In the present invention, the axial direction and the vertical direction of the entire device are consistent.

[0046] Complying with the above - mentioned technical solutions, the following gives specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations made on the basis of the technical solutions of this application fall within the protection scope of the present invention.

[0047] Embodiment:

[0048] This embodiment provides a defoaming device for air - screw foam drilling in gas drainage holes in coal mines, as Figure 1 shown, which includes a vertically arranged foam inlet pipe 1. The bottom of the foam inlet pipe 1 is fixedly connected to one end of the inlet pipe fixed flange 2, and the other end of the inlet pipe fixed flange 2 is provided with a first - stage intake air defoaming unit 3.

[0049] As Figure 1As shown in the figure, the primary intake air defoaming unit 3 includes a primary upper flange 301. One end of the primary upper flange 301 is sealingly connected to the other end of the inlet pipe fixed flange 2. The other end of the primary upper flange 301 is shoulder-connected to one end of a coaxially arranged primary cyclone tube 302. The other end of the primary cyclone tube 302 is sealingly connected to one end of a coaxially arranged primary connecting pipe 303. The lower surface of the flange plate of the primary upper flange 301 is also provided with a primary upper flange annular groove 304. The other end of the primary upper flange 301 is also embedded and fixedly sealed to one end of a coaxially arranged primary intake air outer cylinder 305 through the primary upper flange annular groove 304. The primary intake air outer cylinder 305 is coaxially sleeved outside the primary cyclone tube 302 and the primary connecting pipe 303. The other end of the primary intake air outer cylinder 305 is coaxially provided with a primary lower flange 306. The upper surface of the flange plate of the primary lower flange 306 is provided with a primary lower flange annular groove 307. One end of the primary lower flange 306 is embedded and fixedly sealed to the other end of the primary intake air outer cylinder 305 through the primary lower flange annular groove 307. One end of the primary lower flange 306 is also shoulder-connected to the other end of the coaxially arranged primary connecting pipe 303.

[0050] As Figure 1 shown, a primary intake air pipe 30801 is horizontally arranged on the side wall of the primary intake air outer cylinder 305. The annular cavity formed by the interior of the primary intake air outer cylinder 305 and the exterior of the primary cyclone tube 302, as well as the annular cavity formed by the interior of the primary intake air outer cylinder 305 and the exterior of the primary connecting pipe 303, is the primary air distribution space 30802.

[0051] As Figure 1 shown, a plurality of primary cyclone tube tangential inlet channels 30803 are evenly arranged circumferentially on the side wall of the primary cyclone tube 302. Each primary cyclone tube tangential inlet channel 30803 is tangent to the side wall of the primary cyclone tube 302. The channel connecting the primary intake air pipe 30801, the primary air distribution space 30802, and the primary cyclone tube tangential inlet channels 30803 is the primary air distribution channel 308.

[0052] As Figure 1 shown, the cavity at the center inside the foam inlet pipe 1 is the foam suction chamber 5.

[0053] As Figure 1 shown, the cavity at the center inside the primary cyclone tube 302 and the cavity at the center inside the primary connecting pipe 303 form the primary defoaming chamber 309. The primary defoaming chamber 309 is connected to the foam suction chamber 5.

[0054] As a preferred solution of this embodiment, as Figures 2(a) to 2(c) shown, the shape of the cavity at the center inside the primary cyclone tube 302 is a straight cylinder shape.

[0055] As Figure 3As shown, the cavity shape at the center inside the primary connecting pipe 303 is also straight cylindrical.

[0056] As Figure 1 shown, the diameter of the primary defoaming chamber 309 is 60 - 100 mm.

[0057] As Figure 1 shown, multiple tangential inlet channels 30803 of the primary cyclone tubes are uniformly arranged along the circumferential direction of the primary cyclone tube 302 on the same horizontal line. Each tangential inlet channel 30803 of the primary cyclone tube is the same and has a diameter of 8 - 15 mm. The setting direction of each tangential inlet channel 30803 of the primary cyclone tube is obliquely downward, and the included angle between the central axis inside each tangential inlet channel 30803 of the primary cyclone tube and the horizontal direction is θ, and 0° < θ ≤ 30°.

[0058] In this embodiment, the diameter of the primary defoaming chamber 309 is 80 mm.

[0059] In this embodiment, each tangential inlet channel 30803 of the primary cyclone tube is the same and has a diameter of 11 mm.

[0060] In this embodiment, the included angle between the central axis inside each tangential inlet channel 30803 of the primary cyclone tube and the horizontal direction is 15°.

[0061] In this embodiment, since the helical flow will generate an upward helical motion when encountering the conical surface, weakening the negative pressure generation effect of the helical flow, the cavity shape at the center inside the primary connecting pipe 303 is straight cylindrical.

[0062] In this embodiment, to ensure that the entire device can produce a good negative pressure effect to treat the foam and will not be blocked by the upward returning cuttings to cause pressure buildup, the diameter of the primary defoaming chamber 309 is 80 mm, and the diameter of each tangential inlet channel 30803 of the primary cyclone tube is 11 mm.

[0063] In this embodiment, the number of tangential inlet channels 30803 of the primary cyclone tube is 2. The settings of the tangential inlet channels 30803 of the primary cyclone tube and the tangential inlet channels 703 of the secondary cyclone tube not only ensure that the generated helical flow has an axial velocity along the gravity direction, and the two helical flows can converge and strengthen, but also prevent the gas from escaping to the inlet of the foam inlet pipe 1, affecting the negative pressure effect during defoaming and the suction effect on the upward returning foam at the orifice.

[0064] As a preferred solution of this embodiment, as shown in Fig. 2(c), the bottom of the primary cyclone tube 302 is arranged in a convex shape along the circumferential direction. As Figure 3 shown, the top of the primary connecting pipe 303 is arranged in a concave shape along the circumferential direction, and the concave of the primary connecting pipe 303 can be hermetically connected to the convex of the primary cyclone tube 302.

[0065] As a preferred solution of this embodiment, as Figure 1 shown, a first sealing ring 6 is coaxially arranged at the connection between the inlet pipe fixed flange 2 and the first-stage upper flange 301.

[0066] As a preferred solution of this embodiment, as Figure 1 shown, the other end of the first-stage lower flange 306 is hermetically connected to one end of the second-stage air inlet defoaming unit 7, the other end of the second-stage air inlet defoaming unit 7 is hermetically connected to one end of the tail pipe fixed flange 8, and the other end of the tail pipe fixed flange 8 is fixedly connected to one end of the coaxially arranged tail pipe 4.

[0067] As Figure 1 shown, the structure of the second-stage air inlet defoaming unit 7 is the same as that of the first-stage air inlet defoaming unit 3.

[0068] As a preferred solution of this embodiment, as Figure 1 shown, the second-stage air inlet defoaming unit 7 includes a second-stage upper flange 701, the second-stage upper flange 701 is located at the bottom of the first-stage lower flange 306 and is coaxially arranged, and one end of the second-stage upper flange 701 is hermetically connected to the other end of the first-stage lower flange 306.

[0069] The second-stage air inlet defoaming unit 7 further includes a second-stage lower flange 702, the second-stage lower flange 702 is located at the bottom of the second-stage upper flange 701 and is coaxially arranged, a tail pipe fixed flange 8 is also coaxially arranged at the bottom of the second-stage lower flange 702, the second-stage lower flange 702 is fixedly connected to one end of the tail pipe fixed flange 8, the other end of the tail pipe fixed flange 8 is fixedly connected to one end of the coaxially arranged tail pipe 4, and one end of the tail pipe 4 is communicated with the outside.

[0070] As a preferred solution of this embodiment, as Figure 1 shown, the second-stage air inlet defoaming unit 7 further includes a second-stage cyclone tube tangential inlet channel 703, and the structure of the second-stage cyclone tube tangential inlet channel 703 is the same as that of the first-stage cyclone tube tangential inlet channel 30803.

[0071] The distance between the center point at the outlet of the second-stage cyclone tube tangential inlet channel 703 and the center point at the outlet of the first-stage cyclone tube tangential inlet channel 30803 is 100 - 200 mm; to prevent the phenomenon that the foam flows through the negative pressure area before it has time to expand and break due to too fast flow rate.

[0072] In this embodiment, the distance between the center point at the outlet of the second-stage cyclone tube tangential inlet channel 703 and the center point at the outlet of the first-stage cyclone tube tangential inlet channel 30803 is 150 mm.

[0073] In this embodiment, by adjusting the length of the first-stage connecting pipe 303, the distance between the center point at the outlet of the tangential inlet channel 703 of the second-stage cyclone tube and the center point at the outlet of the tangential inlet channel 30803 of the first-stage cyclone tube can be directly adjusted.

[0074] In this embodiment, the defoaming chamber of the second-stage air intake defoaming unit 7 is hermetically connected to the first-stage defoaming chamber 309.

[0075] As a preferred solution of this embodiment, as Figure 1 shown, a second sealing ring 10 is coaxially arranged at the connection between the first-stage lower flange 306 and the second-stage air intake defoaming unit 7.

[0076] As Figure 1 shown, a third sealing ring 11 is coaxially arranged at the connection between the second-stage air intake defoaming unit 7 and the tail pipe fixing flange 8.

[0077] In this embodiment, based on the reasons for the wear of key parts during the use of this device and the convenience of replacing parts, the entire device is set to be connected by concave-convex platforms or flanges.

[0078] In this embodiment, the connections between all parts in the entire device are sealing connections.

[0079] In this embodiment, the settings of the first-stage upper flange annular groove 304, the first-stage lower flange annular groove 307, the first sealing ring 6, the second sealing ring 10, and the third sealing ring 11 are all to ensure the airtightness of the entire device and prevent the escape of high-pressure gas.

[0080] The working principle of the device in this embodiment is as follows: High-pressure gas enters the first-stage gas distribution space 30802 through the first-stage air inlet pipe 30801. Since the first-stage cyclone tube 302 is provided with double tangential inlets, namely the tangential inlet channel 30803 of the first-stage cyclone tube, the high-pressure gas generates a spiral flow after being ejected at high speed through the double tangential inlets. Due to the large tangential velocity of the spiral flow, a large negative pressure area is generated at the central axis of the entire device. Under the action of the internal and external pressure difference, the foam is prone to expand and break. At the same time, since the tangential inlet channel 30803 of the first-stage cyclone tube is set at a downward angle, the high-speed gas passing through the tangential inlet channel 30803 of the first-stage cyclone tube has a downward axial velocity, which is conducive to the formation of negative pressure at the lower end of the foam suction chamber 5 and generates a suction effect on the foam, sucking the foam into the entire device. Further, the axial component velocity and the tangential component velocity of the high-speed spiral flow are much greater than the velocity of the sucked foam mixed fluid, which is easy to generate a differential shear effect on the foam fluid. The high-speed spiral flow generates a centrifugal effect on the foam fluid, and the solid phase in the foam fluid is more easily separated, further destroying the stability of the foam fluid and being beneficial to the elimination of foam. Finally, a large amount of injected gas will have an air saturation effect on the foam, making the liquid film of the foam thinner and further promoting the elimination of foam.

[0081] The air intake defoaming method of the secondary air intake defoaming unit 7 is the same as that of the primary air intake defoaming unit 3. High-pressure gas is simultaneously introduced into the primary air intake pipe 30801 and the air intake pipe of the secondary air intake defoaming unit 7 to promote the complete elimination of foam.

[0082] The working process of the device in this embodiment is as follows: High-pressure gas enters the primary air distribution space 30802 through the primary air intake pipe 30801, and then a high-speed co-directional spiral flow is generated in the primary defoaming chamber 309 through the tangential inlet channel 30803 of the primary cyclone tube. The flow rate of the high-pressure gas increases and the pressure decreases. At this time, the negative pressure generated at the lower end of the foam suction chamber 5 sucks the foam at the foam inlet, causing the foam to enter the primary defoaming chamber 309. Due to a large negative pressure generated in the middle of the high-speed spiral flow, the sucked foam expands and breaks under the action of the negative pressure. At the same time, the high-pressure gas enters the defoaming chamber of the secondary air intake defoaming unit 7 through the air intake pipe of the secondary air intake defoaming unit 7, and a high-speed co-directional spiral flow is also generated in the defoaming chamber of the secondary air intake defoaming unit 7 through the tangential inlet channel 703 of the secondary cyclone tube. The two spiral flows are mixed in the defoaming chamber of the secondary air intake defoaming unit 7 to eliminate the foam that is not completely treated in the primary defoaming chamber 309. The mixed fluid after being treated in the primary defoaming chamber 309 and the mixed fluid after being treated in the defoaming chamber of the secondary air intake defoaming unit 7 are discharged together through the tail pipe 4.

[0083] According to the air volume provided by the on-site air compressor, the total inlet air volume of the entire device is set to 2 m 3 / min, 4 m 3 / min, 6 m 3 / min, 8 m 3 / min and 10 m 3 / min respectively and simulation is carried out. The simulation results are as Figures 4(a) to 4(d) shown (the reference origin is located at the bottom of the device), which proves that the device can generate a large negative pressure value under medium and high air volume conditions. When the air volume exceeds 6 m 3When the air volume is 10 m³ / min, the average negative pressure value of the central axis reaches above -7 KPa; as the air volume continues to increase, both the maximum negative pressure and the average negative pressure of the central axis increase in multiples. There are two adjacent troughs in the pressure distribution of the central axis. The front trough is much lower than the rear trough, which proves that the primary spiral flow pre-treats the foam, causing the foam to start expanding and the liquid film to become thinner; at the same time, it moves downward and converges with the secondary spiral flow, enhancing the negative pressure effect generated by the secondary spiral flow and the treatment effect on the foam. The existence area of the two troughs runs through between the two-stage inlets. The negative pressure area generated by this device exists throughout the device, increasing the treatment area for the foam and keeping the foam in a negative pressure for as long as possible to expand and break. While treating the foam, due to the negative pressure effect inside the device, a suction effect is generated on the foam inlet. Under the working conditions of medium and high air volumes, the suction volume of this device for the upward-returning foam is similar to the total air volume provided to the defoaming device, and it can well absorb and guide the upward-returning foam in the hole into the device for treatment.

Claims

1. A defoaming device for air screw foam drilling in gas extraction holes in coal mines, characterized in that: It comprises a foam inlet pipe (1) arranged vertically, wherein the bottom of the foam inlet pipe (1) is fixedly connected to one end of an inlet pipe fixing flange (2), and the other end of the inlet pipe fixing flange (2) is provided with a first-stage air intake defoaming unit (3); The first-stage air intake defoaming unit (3) comprises a first-stage upper flange (301), one end of the first-stage upper flange (301) is sealedly connected to the other end of the inlet pipe fixed flange (2), the other end of the first-stage upper flange (301) is connected to a shoulder of one end of a coaxially arranged first-stage cyclone tube (302), the other end of the first-stage cyclone tube (302) is sealedly connected to one end of a coaxially arranged first-stage connecting pipe (303), the lower surface of the flange plate of the first-stage upper flange (301) is also provided with a first-stage upper flange annular groove (304), and the other end of the first-stage upper flange (301) is also connected to the coaxially arranged first-stage air intake pipe outer cylinder (303) through the first-stage upper flange annular groove (304). 5), one end of the first-stage air inlet pipe outer tube (305) is embedded, fixed and sealed, the first-stage air inlet pipe outer tube (305) is coaxially sleeved on the outside of the first-stage cyclone tube (302) and the first-stage connecting tube (303), the other end of the first-stage air inlet pipe outer tube (305) is coaxially provided with a first-stage lower flange (306), the upper surface of the flange plate of the first-stage lower flange (306) is provided with a first-stage lower flange annular groove (307), one end of the first-stage lower flange (306) is embedded, fixed and sealed with the other end of the first-stage air inlet pipe outer tube (305) through the first-stage lower flange annular groove (307), and one end of the first-stage lower flange (306) is also connected to the other end shoulder of the coaxially provided first-stage connecting tube (303); A first-stage air intake pipe (30801) is transversely arranged on the upper side wall of the first-stage air intake pipe outer tube (305); an annular cavity formed by the interior of the first-stage air intake pipe outer tube (305) and the exterior of the first-stage cyclone tube (302), as well as the interior of the first-stage air intake pipe outer tube (305) and the exterior of the first-stage connecting tube (303) is a first-stage air distribution space (30802); A plurality of first-level cyclone tube tangential inlet channels (30803) are evenly arranged along the circumferential direction on the side wall of the first-level cyclone tube (302), each first-level cyclone tube tangential inlet channel (30803) is tangent to the side wall of the first-level cyclone tube (302), and a channel connecting the first-level air inlet pipe (30801), the first-level air distribution space (30802) and the first-level cyclone tube tangential inlet channel (30803) is a first-level air distribution channel (308); The cavity at the center of the foam inlet pipe (1) is a foam suction chamber (5); The cavity at the center of the first-stage cyclone tube (302) and the cavity at the center of the first-stage connecting tube (303) form a first-stage defoaming chamber (309), and the first-stage defoaming chamber (309) is connected to the foam suction chamber (5).

2. The defoaming device for air screw foam drilling in underground coal mine gas extraction holes as claimed in claim 1, characterized in that: The cavity shape at the inner center of the first-stage cyclone tube (302) is a straight cylinder; The shape of the cavity in the center of the first-level connecting pipe (303) is also a straight cylinder; The diameter of the primary defoaming chamber (309) is 60 to 100 mm; The multiple first-level cyclone tube tangential inlet channels (30803) are evenly arranged on the same horizontal line along the circumference of the first-level cyclone tube (302), each first-level cyclone tube tangential inlet channel (30803) is the same and has a diameter of 8 to 15 mm, and each first-level cyclone tube tangential inlet channel (30803) is arranged in an oblique downward direction. The angle between the central axis of each first-level cyclone tube tangential inlet channel (30803) and the horizontal direction is θ, and 0°<θ≤30°.

3. The defoaming device for air screw foam drilling in underground coal mine gas extraction holes as claimed in claim 1, characterized in that: The bottom of the first-stage cyclone tube (302) is circumferentially arranged in a boss shape, and the top of the first-stage connecting tube (303) is circumferentially arranged in a concave shape, and the concave of the first-stage connecting tube (303) and the boss of the first-stage cyclone tube (302) can be sealed and connected.

4. The defoaming device for air screw foam drilling in underground coal mine gas extraction holes as claimed in claim 1, characterized in that: A first sealing ring (6) is coaxially arranged at the connection between the inlet pipe fixing flange (2) and the first-level upper flange (301).

5. The defoaming device for air screw foam drilling in underground coal mine gas extraction holes as claimed in claim 1, characterized in that: The other end of the first-stage lower flange (306) is sealedly connected to one end of the second-stage air intake defoaming unit (7), the other end of the second-stage air intake defoaming unit (7) is sealedly connected to one end of the tail pipe fixing flange (8), and the other end of the tail pipe fixing flange (8) is fixedly connected to one end of the coaxially arranged tail pipe (4); The structure of the secondary air intake and defoaming unit (7) is the same as that of the primary air intake and defoaming unit (3).

6. The defoaming device for air screw foam drilling in underground coal mine gas extraction holes as claimed in claim 5, characterized in that: The secondary air intake defoaming unit (7) comprises a secondary upper flange (701), the secondary upper flange (701) is located at the bottom of the primary lower flange (306) and is coaxially arranged, and one end of the secondary upper flange (701) is sealed and connected to the other end of the primary lower flange (306); The secondary air intake defoaming unit (7) further comprises a secondary lower flange (702), which is located at the bottom of the secondary upper flange (701) and is coaxially arranged. A tail pipe fixing flange (8) is also coaxially arranged at the bottom of the secondary lower flange (702). The secondary lower flange (702) is fixedly connected to one end of the tail pipe fixing flange (8), and the other end of the tail pipe fixing flange (8) is fixedly connected to one end of a coaxially arranged tail pipe (4), and one end of the tail pipe (4) is connected to the outside.

7. The defoaming device for air screw foam drilling in underground coal mine gas extraction holes as claimed in claim 5, characterized in that: The secondary air intake defoaming unit (7) further comprises a secondary cyclone tube tangential inlet channel (703), and the structure of the secondary cyclone tube tangential inlet channel (703) is the same as the structure of the primary cyclone tube tangential inlet channel (30803); The distance between the center point of the outlet of the tangential inlet channel (703) of the secondary cyclone tube and the center point of the outlet of the tangential inlet channel (30803) of the primary cyclone tube is 100 to 200 mm.

8. The defoaming device for air screw foam drilling in underground coal mine gas extraction holes as claimed in claim 5, characterized in that: A second sealing ring (10) is coaxially arranged at the connection between the first-stage lower flange (306) and the second-stage air inlet defoaming unit (7); A third sealing ring (11) is coaxially arranged at the connection between the secondary air intake defoaming unit (7) and the tail pipe fixing flange (8).

Images