Direct test method for harmful gas content in coal and rock strata based on freeze sampling process

Abstract

The present invention relates to a direct testing method for the content of harmful gases in coal and rock strata based on a freezing sampling process, comprising the following steps: S1: Install a three-wing concave drill bit at the end of a double-layer end drill pipe. The end drill pipe, double-layer drill pipe, and tail joint are connected end to end. A sampling assembly is installed inside the end drill pipe, in the front part of the inner layer pipe at the end of the end drill pipe. Connect the rear end of the end drill pipe to the inner and outer layer pipes of the double-layer drill pipe correspondingly, and connect the tail joint to the cold end pipe of the vortex tube; S2: Start the drilling rig to cut the coal body; S3: After drilling to the specified distance, stop drilling, remove the connection between the double-layer drill pipe and the tail joint, add a new double-layer drill pipe, and then connect the double-layer drill pipe to the tail interface; Repeat S2 to S3 until drilling reaches the predetermined sampling position; S4: The sampling assembly takes a sample; S5: Remove the storage tube after sampling, and then turn on the Roots vacuum pump to detect the coal sample.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mine safety, and relates to a direct test method for the content of harmful gases in coal and rock strata based on a freezing sampling process. Background Art

[0002] Gas is one of the main threats to the safe production of coal mines. It is a combustible gas mainly composed of methane and exists in coal seams or surrounding rocks in adsorbed and free forms. In recent years, in the production practices of many mining areas in China, it has been found that the mixed gas of hydrogen sulfide gas and methane during coal mining has constituted a new disaster.

[0003] Hydrogen sulfide is a flammable acidic gas under standard conditions, colorless, with a rotten egg smell at low concentrations, a sulfur smell at extremely low concentrations, and highly toxic. Hydrogen sulfide gas can dissolve in water and is easily soluble in alcohols, petroleum solvents, and crude oil. Therefore, during the production process of such coal mines, it is necessary to accurately master the content distribution of the mixed gas of coal seam methane and hydrogen sulfide in order to provide technical guarantees for the safe and stable supply of coal and the physical and mental health of underground workers.

[0004] The coal seam gas content measured by the most commonly used direct method underground in China at present consists of three parts: the underground gas desorption amount of the coal sample, the residual gas amount in the laboratory, and the gas loss amount during the sampling process. The first two can be measured directly, while the gas loss amount is calculated based on the desorption law of the coal sample in the first few minutes underground and the coring time. The calculation result of the gas loss amount is greatly affected by the sampling method.

[0005] Common sampling methods include:

[0006] (1) The cuttings sampling method is simple to operate but prone to sample mixing, and it is impossible to ensure the purity of the coal sample, so the reliability of its measurement results is difficult to guarantee;

[0007] (2) The core barrel method can achieve fixed-point sampling in the coal seam, and the sampling depth is also relatively long. However, during the sampling process, due to the heat generated by the drill bit cutting the coal body and the friction between the pipe wall and the borehole wall, the temperature of the core barrel wall rises, which exacerbates the gas desorption rate of the coal core during the sampling process. Therefore, the gas loss amount during the actual coring process is larger than the calculated value in the normal temperature environment. When the coring time is long, the samples taken may even not desorb; in addition, this method is not suitable for measuring the content of harmful gases when hydrogen sulfide gas is present, because hydrogen sulfide gas is very active and reacts immediately when heated;

[0008] (3) The positive pressure reverse circulation air pressure sampling and negative pressure jet sampling technologies can both achieve fixed-point sampling and shorten the sampling time, but they have high requirements for air pressure, and it does not conform to the actual situation to calculate the gas loss amount in the positive pressure or negative pressure environment based on the desorption law of the coal core under normal pressure;

[0009] (4) The purpose of the closed - liquid closed and pressure - maintained coring technology is to prevent or reduce the gas leakage during the coring process. However, sometimes the closed liquid cannot completely wrap the coal core, and even pollutes the coal sample. This method has not been accepted by engineering applications;

[0010] (5) The frozen - coring coal - seam gas - content measurement technology means that when drilling reaches the predetermined coring position, replace it with a frozen - coring device to complete the drilling and sampling. The coal core rapidly drops below 0°C under the action of the refrigerant, as much as possible slowing down the gas desorption of the coal core during the coring process and reducing the gas loss. However, this technology requires immediately withdrawing the drill after drilling to the predetermined position, and then replacing the frozen - coring device to drill the coal sample. Therefore, the process from withdrawing the drill to replacing the frozen - coring device will cause gas loss in the sampled coal body.

[0011] In summary, several commonly used direct measurement methods for the harmful gas content in coal and rock strata all have deficiencies to varying degrees. The core lies in how to achieve sampling while drilling during the drilling process, and being able to eliminate or minimize gas loss during the sampling process is the key to accurately and reliably measuring the harmful gas content in coal and rock strata. Summary of the Invention

[0012] In view of this, the purpose of the present invention is to provide a direct test method for the harmful gas content in coal and rock strata based on the frozen - sampling process that can solve the above - mentioned problems.

[0013] To achieve the above - mentioned purpose, the present invention provides the following technical solutions:

[0014] A direct test method for the harmful gas content in coal and rock strata based on the frozen - sampling process, comprising the following steps:

[0015] S1: Install a three - wing concave drill bit at the front end of the outer layer pipe of the double - layer end drill pipe, install a sampling assembly for taking coal samples at the front part of the inner layer pipe of the end drill pipe, connect the rear end of the end drill pipe to the inner and outer layer pipes of the double - layer drill pipe correspondingly, then connect one end of the outer side of the double - layer drill pipe to the clamping device on the drilling rig, and connect the end of the double - layer drill pipe to the tail joint; Connect the tail outer - pipe interface of the tail joint and the tail inner - pipe interface of the tail joint to the cold - end pipe of the vortex tube respectively; Connect the compressed - air wind pipe in the coal mine to the nozzle end of the vortex tube;

[0016] S2: Start the drilling rig to cut the coal body; During this process, the compressed air in the coal mine is cooled and heat - separated through the vortex chamber of the vortex tube, and the cold air enters the inner - pipe space and the space between the double - layer pipes respectively to cool the coal body and discharge the coal slag;

[0017] S3: After drilling to a certain distance, stop drilling, remove the connection between the double-layer drill pipe and the tail joint, add a new double-layer drill pipe, and then connect the double-layer drill pipe to the tail joint; repeat S2 - S3 until drilling reaches the predetermined sampling position;

[0018] S4: After drilling reaches the predetermined sampling position, close the air inlet of the inner layer pipe of the double-layer drill pipe, continue drilling, and during this process, the sampling assembly samples. After sampling is completed, close the compressed air source and remove the connection between the tail inner pipe interface and the eddy current tube. Then, place the rubber ball into the tail joint through the inner pipe joint; then, connect the tail inner pipe joint to one end of the eddy current tube through a high-pressure rubber hose again, and open the compressed air source, so that the rubber ball enters the ball seat of the sampling assembly under the action of cold air, and drives the sealing actuator block to cut off the coal chips at the inlet of the storage pipe. At the same time, the sealing rubber integrated with the support frame is pressed into the rear opening of the storage pipe, and the storage pipe is sealed;

[0019] S5: Remove the sampling assembly from the end drill pipe, take down the storage pipe, connect the needle valve provided on the storage pipe to the silica gel tube provided on the test pipeline, and then turn on the Roots vacuum pump to detect the coal sample.

[0020] Further, the sampling assembly mentioned in the steps includes a delivery pipe and an inner drill pipe with spiral blades. The spiral blades are fixed on the outer circumference of the inner drill pipe. The inner drill pipe is placed inside the delivery pipe and is coaxial with the delivery pipe. The tail end of the delivery pipe is fixed to the front end of a cylindrical positioning block. The cylindrical positioning block is fixed to the inner wall of the end inner layer pipe. A sealing actuator block is arranged behind the cylindrical positioning block. The sealing trigger rod passes through the sealing actuator block and the cylindrical positioning block in sequence. A storage pipe corresponding to the delivery pipe is fixed behind the sealing actuator block. The pressurizing frame provides power for the sealing trigger rod, and the movement of the sealing trigger rod can seal the front end of the storage pipe by the sealing actuator block.

[0021] Further, the sealing trigger rod successively includes a trigger rod front part, a trigger part, and a trigger rod rear part which are integrally designed from front to back. The trigger rod front part is a horizontal rod, and the tail end of the trigger rod front part is integrally connected to the front end of the trigger part. The trigger part is an inclined connecting rod, and the rear end of the trigger part is inclined towards the axis of the end inner layer pipe. The trigger rod rear part is a horizontal rod, and the tail end of the trigger part is integrally connected to the front end of the trigger rod rear part. The cross-section of the sealing trigger rod is a rectangular surface. A trigger groove matching the trigger part is opened on the corresponding sealing actuator block. The trigger groove includes a rectangular groove vertically penetrating the sealing actuator block. On one side of the front part of the rectangular groove close to the outer wall of the sealing actuator block, a front inclined groove communicating with the rectangular groove is arranged. On one side of the rear part of the rectangular groove close to the semi-cylindrical block, a rear inclined groove communicating with the rectangular groove is arranged. The front inclined groove and the rear inclined groove are communicated, and just match the trigger part after being communicated.

[0022] Furthermore, the rear end of the sealing trigger rod is fixedly connected through a support frame. A sealing rubber is fixedly provided on one side of the middle part of the support frame facing the storage pipe. An opening is formed at the rear end of the storage pipe. The sealing rubber is matched with this opening and can block this opening. The front end of the push rod is fixed on the rear end of the middle part of the support frame, and the rear end of the push rod is connected to the output inclined body arranged in the pressurization frame.

[0023] Furthermore, an output inclined body, a force transmission round block, and an input inclined body that can slide are sequentially arranged in the pressurization frame from front to back. The rear end of the push rod passes through the front side frame of the pressurization frame and then enters the interior of the pressurization frame and is fixed on the front end face of the output inclined body. A first spring is sleeved on the push rod between the front end face of the output inclined body and the opposite side wall of the pressurization frame. The rear end of the input inclined body extends to the outside of the pressurization frame and is provided with a limiting step integrated with the input inclined body. A second spring is arranged between the limiting step and the rear side wall of the pressurization frame. A ball seat with an opening facing backward is fixed on the rear side wall of the limiting step, and the ball seat is matched with a rubber ball.

[0024] Furthermore, the side wall of the input inclined body facing the force transmission round block is an inclined surface, and the side wall of the output inclined body facing the force transmission round block is also an inclined surface. The included angle between the inclined surface of the input inclined body and the horizontal plane is smaller than the included angle between the inclined surface of the output inclined body and the horizontal plane.

[0025] Furthermore, in step S5, when the reading of the vacuum thermocouple is less than 20, open the needle valve of the storage pipe, and at the same time turn on the mass flow sensor, gas concentration sensor, and monitoring system, and record the flow rate of the gas flowing out of the storage pipe and the concentration values of methane and hydrogen sulfide gases; until the reading of the mass flow sensor is 0 and the reading of the vacuum thermocouple on the roots vacuum pump is less than 20, the roots vacuum pump, mass flow sensor, and gas concentration sensor can be turned off.

[0026] Furthermore, the mass flow sensor and gas concentration sensor are arranged on the test pipeline resistant to hydrogen sulfide gas corrosion, and the inner diameters of the straight pipe sections at the inlet and outlet ends of the mass flow sensor are not less than 10 times and 5 times the inner diameter of the test pipeline respectively. The test pipeline and the storage pipe need to be placed in a constant temperature air bath, and the temperature set by the constant temperature air bath should be consistent with the coal seam temperature..

[0027] Furthermore, it includes step S6. Extract the gas flow rate and concentration data stored in the monitoring system, and define the gas flow rate data under standard conditions as q m 3 / s, methane concentration hydrogen sulfide concentration Use the method of polynomial fitting in numerical analysis to obtain the function of gas flow rate and time t as q(t), the function of methane concentration and time t as the function of hydrogen sulfide concentration and time t as Then, further through the method of definite integral, the cumulative gas volume can be obtained as:

[0028]

[0029] Where: Q is the cumulative gas volume in the collected coal sample under standard conditions, m 3 ; t c is the pumping time of the Roots vacuum pump for the collected coal sample, s.

[0030] Further, it includes step S7. After step S6, the coal sample is taken out from the storage pipe and its weight is measured and defined as M. Then the content of harmful gases in the coal seam is Q / M; the methane gas content in the coal seam is The hydrogen sulfide gas content in the coal seam is

[0031] The beneficial effects of the present invention are as follows:

[0032] (1) By using the method of connecting the vortex tube to the compressed air source in the coal mine to conduct cold and heat separation of the air, the separated cold air is used as the slag discharge medium during the drilling process, and at the same time, the moisture in the coal body in front of the drill tool condenses into ice, thereby blocking the channels for the migration of gas and hydrogen sulfide gas in the coal body, preventing the escape of gas and hydrogen sulfide gas in the coal sample during the sampling process, and effectively ensuring the reliability of the test results;

[0033] (2) During the construction process of the present invention, it can sample the coal body at a specific position without replacing the core sampling device, and uses the cold air source below zero as the medium for slag discharge and freezing the coal body, without polluting the coal body;

[0034] (3) The present invention adopts the method of an internal spiral blade and a storage pipe to realize the collection and storage of the coal sample during the sampling process, and realizes the sealing of the storage pipe through the subsequent structure of the rubber ball impacting the ball seat and combined with pressure boosting conduction; abandons the traditional method of collecting the gas escaped from the coal sample by the drainage method, conducts degassing on the coal sample in a constant temperature state through a Roots vacuum pump, further obtains the function corresponding to time by using the method of polynomial fitting for the online monitoring data of flow rate and concentration, and finally can accurately obtain the methane and hydrogen sulfide gas contents in the coal sample through the method of integration.

[0035] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0037] Figure 1 It is a sectional view at the end drill pipe of the present invention;

[0038] Figure 2 It is a sectional view at the double-layer drill pipe and the tail joint;

[0039] Figure 3 It is Figure 1 The sectional view at A-A in

[0040] Figure 4 It is Figure 1 The sectional view at B-B in

[0041] Figure 5 It is Figure 1 The sectional view at C-C in

[0042] Figure 6 It is a sectional view of the structure at the seal trigger rod, the cylindrical positioning block and the seal actuator block;

[0043] Figure 7 It is a sectional view of the tee;

[0044] Figure 8 It is a sectional view of the vortex tube;

[0045] Figure 9 It is a structural schematic diagram of the detection device.

[0046] Reference numerals:

[0047] 100, End drill pipe; 110, Outer end pipe; 120, Inner end pipe; 130, Step hole one; 140, Step hole two; 200, Double-layer drill pipe; 210, Drill pipe outer tube; 220, Drill pipe inner tube; 300, Tail joint; 310, Tail outer tube; 311, Tail outer tube interface; 320, Tail inner tube; 321, Tail inner tube interface; 330, Rotary joint; 340, Bearing; 400, Three-wing concave bit; 410, Diamond pick; 500, Sampling assembly; 510, Delivery pipe; 520, Built-in drill pipe; 521, Spiral blade; 522, Spiral drill bit; 530, Cylindrical positioning block; 540, Sealing actuator block; 541, Semi-cylindrical block; 542, Rectangular groove; 543, Front inclined groove; 544, Rear inclined groove; 550, Sealing trigger rod; 551, Front trigger rod; 552, Trigger part; 553, Rear trigger rod; 560, Storage pipe; 561, Fixed support plate; 570, Push rod; 571, Sealing rubber; 572, Needle valve; 573, Spring one; 580, Support frame; 590, Boosting frame; 591, Output italic; 592, Force transfer round block; 593, Input italic; 5931, Limit port; 594, Limit step; 595, Spring two; 596, Ball seat; 597, Rubber ball; 598, Limit hemisphere; 600, Three-way; 610, Valve one; 620, Valve two; 630, Valve three; 700, Vortex tube; 710, Cold end pipe; 720, Nozzle end; 730, Hot end pipe; 800, Roots vacuum pump; 810, Vacuum thermocouple gauge; 820, Test pipe one; 830, Test pipe two; 840, Silicone tube; 850, Mass flow sensor; 860, Gas concentration sensor; 870, Monitoring system; 880, Air bath. Detailed implementation manners

[0048] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the diagrams provided in the following embodiments only schematically illustrate the basic concept of the present invention. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0049] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and cannot be understood as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0050] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the accompanying drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the accompanying drawings are only for illustrative purposes and cannot be construed as a limitation of the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0051] Please refer to Figures 1 to 9 , which is a direct test method for the content of harmful gases in coal and rock strata based on a freezing sampling process, including a three-wing concave drill bit 400 and a sampling assembly 500. The three-wing concave drill bit 400 is fixed at the front end of the end drill pipe 100, and the sampling assembly 500 is located inside the front ends of the three-wing concave drill bit 400 and the end drill pipe 100. The rear end of the end drill pipe 100 is detachably and fixedly connected to the front end of the double-layer drill pipe 200. One end of the outer side of the double-layer drill pipe 200 is connected to the clamping device on the drilling rig, and the rear end of the double-layer drill pipe 200 is fixedly connected to the front end of the tail joint 300. The rear end of the tail joint 300 is connected to the vortex tube 700 through a tee 600.

[0052] The end drill pipe 100, the double-layer drill pipe 200, and the tail joint 300 are all of double-tube structures. The inner tube spaces of the end drill pipe 100, the double-layer drill pipe 200, and the tail joint 300 are connected in sequence. The spaces between the outer tubes and the inner tubes of the end drill pipe 100, the double-layer drill pipe 200, and the tail joint 300 are connected in sequence. The inner tube and the outer tube are connected by a key, and the inner tube and the outer tube rotate simultaneously. The design of the double-tube structure is for slag discharge during the drilling process.

[0053] The tail joint 300 includes a tail outer tube 310 and a tail inner tube 320. A tail outer tube interface 311 is provided on the tail outer tube 310, and a tail inner tube interface 321 is provided on the tail inner tube 320. The tail outer tube interface 311 is connected to the valve one 610 of the tee 600 through a high-pressure rubber hose; the tail inner tube interface 321 is connected to the valve two 620 of the tee 600 through a high-pressure rubber hose; the valve three 630 of the tee 600 is connected to the cold end tube 710 joint of the vortex tube 700 through a high-pressure rubber hose. The compressed air duct in the coal mine is connected to the nozzle end 720 of the vortex tube 700 through a high-pressure rubber hose. The hot end tube 730 of the vortex tube 700 is emptied.

[0054] In order not to affect the rotation of the tail joint 300 after it is connected to the double-layer drill pipe 200, the tail outer pipe interface 311 and the tail inner pipe interface 321 are respectively connected to the tail outer pipe 310 and the tail inner pipe 320 through rotary joints 330. The tail outer pipe 310 and the tail inner pipe 320 are connected through a bearing 340.

[0055] The double-layer drill pipe 200 includes a drill pipe outer pipe 210 and a drill pipe inner pipe 220. The rear end of the drill pipe outer pipe 210 is fixedly and sealingly connected to the front end of the tail outer pipe 310 by threads. The rear end of the drill pipe inner pipe 220 is fixedly and sealingly connected to the front end of the tail inner pipe 320.

[0056] The end drill pipe 100 includes a coaxial end outer layer pipe 110 and an end inner layer pipe 120. The rear end of the end outer layer pipe 110 is fixedly connected to the front end of the drill pipe outer pipe 210 by threads, and the rear end of the end inner layer pipe 120 is fixedly and sealingly connected to the front end of the drill pipe inner pipe 220.

[0057] The front end of the end outer layer pipe 110 is fixedly connected to a three-wing concave drill bit 400 by threads, and the front end of the three-wing concave drill bit 400 is a diamond cutting tooth 410.

[0058] The sampling assembly 500 includes a delivery pipe 510, a built-in drill pipe 520 with a spiral blade 521, a cylindrical positioning block 530, a sealing execution block 540, a sealing trigger rod 550, a storage pipe 560, a sealing rubber 571, a needle valve 572, a push rod 570, a support frame 580, and a pressurization frame 590.

[0059] The spiral blade 521 is fixed on the outer circumference of the built-in drill pipe 520. The built-in drill pipe 520 is placed inside the delivery pipe 510 and is coaxial with the delivery pipe 510. The front end of the built-in drill pipe 520 is a spiral drill bit 522, and the spiral drill bit 522 protrudes from the front end of the delivery pipe 510. The spiral drill bit 522 is flush with the end of the three-wing concave drill bit 400. The tail of the built-in drill pipe 520 is flush with the tail of the delivery pipe 510. The delivery pipe 510 and the spiral blade 521 are fixed as a whole. A protrusion is provided every 90° on the cross-section of the spiral blade 521, and a groove corresponding to the protrusion is provided on the inner wall of the delivery pipe 510. When assembling, the built-in drill pipe 520 with the spiral blade 521 is embedded in the delivery pipe 510 and fixed.

[0060] The tail end of the delivery pipe 510 is fixed to the front end of the cylindrical positioning block 530. The tail end of the delivery pipe 510 is provided with an external thread for threaded engagement with the front end of the cylindrical positioning block 530. The built-in drill rod 520 with spiral blades 521 is fixed to the cylindrical positioning block 530 by screwing in at the tail end of the delivery pipe 510. The cylindrical positioning block 530 is fixed to the inner wall of the end inner layer pipe 120. The front end of the inner wall of the end inner layer pipe 120 is a step hole one 130, and adjacent to the step hole one 130 is a step hole two 140. The inner diameter of the step hole one 130 is larger than the inner diameter of the step hole two 140. The cylindrical positioning block 530 is embedded in the step hole one 130.

[0061] Behind the cylindrical positioning block 530 are a pair of symmetric sealing actuator blocks 540. The sealing actuator block 540 is a U-shaped structure relative to the sealing trigger rod 550. The front ends of the two trigger rods of the sealing trigger rod 550 pass through the sealing actuator block 540 and the cylindrical positioning block 530 from back to front in sequence. Through holes for facilitating the sliding of the sealing trigger rod 550 are provided on the sealing actuator block 540 and the cylindrical positioning block 530. The sealing trigger rod 550 can slide back and forth relative to the sealing actuator block 540 and the cylindrical positioning block 530. The sealing actuator block 540 is located in the step hole two 140 and abuts against the cylindrical positioning block 530.

[0062] During assembly, first install the sealing actuator block 540 into the step hole one 130, and then assemble the cylindrical positioning block 530 into the step hole one 130 from the front side of the step hole one 130 until the cylindrical positioning block 530 abuts against the step of the step hole two 140. The sealing actuator block 540 abuts closely against the cylindrical positioning block 530.

[0063] The sealing actuator block 540 is sleeved on the corresponding trigger rod of the sealing trigger rod 550. When the sealing trigger rod 550 moves forward, the sealing actuator block 540 can move towards the axis. Semi-cylindrical blocks 541 integrated with the sealing actuator block 540 are provided on the opposite side walls of the sealing actuator block 540. The two semi-cylindrical blocks 541 can be spliced into a complete cylinder. A strong magnetic medium is provided at the edge of the semi-cylindrical block 541, and one cross-section is concave and the other is convex. The concave and convex structural parts are matched with each other, and a rubber sealing pad is provided in the concave groove.

[0064] The storage pipe 560 is located behind the sealing actuator block 540. Four radially outward fixed support plates 561 are fixed on the outer circumferential wall of the storage pipe 560. Corresponding slots are provided on the inner wall of the corresponding end inner layer pipe 120. The fixed support plates 561 are fixed by being stuck in the slots, which is also convenient for disassembly.

[0065] The storage pipe 560 is located inside the sealing trigger rod 550. The trigger rod of the sealing trigger rod 550 passes through the gap between the fixed support plate 561 and then passes through the sealing execution block 540 and the cylindrical positioning block 530.

[0066] Preferably, the cylindrical positioning block 530 and the sealing execution block 540 are provided with a plurality of uniformly distributed sieve holes in the axial direction for providing a flow channel for high-pressure gas during drilling.

[0067] The storage pipe 560 corresponds to the delivery pipe 510. The delivery pipe 510 and the storage pipe 560 are transitioned through the cylindrical positioning block 530 and the sealing execution block 540.

[0068] The sealing trigger rod 550 successively includes a trigger rod front part 551, a trigger part 552, and a trigger rod rear part 553 which are integrally designed from front to back. The trigger rod front part 551 is a horizontal rod. The tail end of the trigger rod front part 551 is integrally connected to the front end of the trigger part 552. The trigger part 552 is an inclined connecting rod. The rear end of the trigger part 552 is inclined towards the axis of the end inner layer pipe 120. The trigger rod rear part 553 is a horizontal rod. The tail end of the trigger part 552 is integrally connected to the front end of the trigger rod rear part 553. The cross-section of the sealing trigger rod 550 is a rectangular surface.

[0069] Correspondingly, a trigger groove matching with the trigger part 552 is formed on the sealing execution block 540. The trigger groove includes a rectangular groove 542 vertically penetrating the sealing execution block 540. On one side of the front part of the rectangular groove 542 close to the outer wall of the sealing execution block 540, a front inclined groove 543 communicating with the rectangular groove 542 is provided. On one side of the rear part of the rectangular groove 542 close to the semi-cylindrical block 541, a rear inclined groove 544 communicating with the rectangular groove 542 is provided. The front inclined groove 543 and the rear inclined groove 544 are communicated. After the front inclined groove 543 and the rear inclined groove 544 are communicated, they just match with the trigger part 552. Such a design enables that when the sealing trigger rod 550 moves forward, when the trigger part 552 moves into the rear inclined groove 544, due to the inward inclination of the trigger part 552, the trigger part 552 pushes the sealing execution block 540 to move inward to realize the sealing of the front end of the storage pipe 560.

[0070] The front end of the push rod 570 is fixed on the middle rear end of the support frame 580. The rear end of the push rod 570 is connected to the pressurizing frame 590. The pressurizing frame 590 pushes the push rod 570, and the push rod 570 pushes the sealing trigger rod 550 to move.

[0071] The rear end of the sealing trigger rod 550 is fixedly connected through the support frame 580. The trigger rod of the sealing trigger rod 550 is fixed on one side of the corresponding support frame 580 through a fixing nut. A sealing rubber 571 is fixed on the middle part of the support frame 580 facing the side of the storage pipe 560. An opening is provided at the rear end of the storage pipe 560, and the sealing rubber 571 can cooperate with this opening to block the opening. A needle valve 572 is arranged on the sealing rubber 571. When the needle valve 572 is opened, the inside of the storage pipe 560 can communicate with the outside.

[0072] An output inclined body 591, a force-transmitting circular block 592, and an input inclined body 593 that can slide are sequentially arranged in the pressurizing frame 590 from front to back. The rear end of the push rod 570 passes through the front frame of the pressurizing frame 590 and then enters the inside of the pressurizing frame 590 and is fixed on the front end face of the output inclined body 591. A first spring 573 is sleeved on the push rod 570 between the front end face of the output inclined body 591 and the opposite side wall of the pressurizing frame 590. The rear end of the input inclined body 593 extends to the outside of the pressurizing frame 590 and then is provided with a limiting step 594 integrated with the input inclined body 593. A second spring 595 is arranged between the limiting step 594 and the rear side wall of the pressurizing frame 590. A ball seat 596 with an opening facing backward is fixed on the rear side wall of the limiting step 594, and the ball seat 596 cooperates with the rubber ball 597.

[0073] After the rubber ball 597 gives a thrust to the ball seat 596, the input inclined body 593 moves towards the force-transmitting circular block 592. The movement of the force-transmitting circular block 592 pushes the output inclined body 591 to move forward. The output inclined body 591 pushes the push rod 570 to move forward. The push rod 570 pushes the support frame 580, and the support frame 580 drives the sealing trigger rod 550 to move forward. The movement of the sealing trigger rod 550 pushes the sealing execution block 540 to move relatively towards the axis, realizing the sealing of the storage pipe 560.

[0074] A protrusion is arranged on the outer wall of the pressurizing frame 590. The protrusion is embedded in the second step hole 140, and the right end of the second step hole 140 realizes the limitation of the right protrusion.

[0075] Preferably, the side wall of the input inclined body 593 facing the force-transmitting circular block 592 is an inclined surface, and the side wall of the output inclined body 591 facing the force-transmitting circular block 592 is also an inclined surface. The included angle between the inclined surface of the input inclined body 593 and the horizontal plane is smaller than the included angle between the inclined surface of the output inclined body 591 and the horizontal plane.

[0076] If the inclined angles of the inclined surfaces of the input inclined body 593 and the output inclined body 591 are A and B respectively, when sampling, the force acting on the ball seat 596 by the rubber ball 597 can be amplified according to the following relationship through the input inclined body 593, the force-transmitting circular block 592, and the output inclined body 591:

[0077] F2 = F1 × tan(B) / tan(A)

[0078] Where A: the inclined plane angle of the input italic 593; B: the inclined plane angle of the output italic 591; F1: the thrust force of the input italic 593; F2: the thrust force of the output italic 591.

[0079] Taking A = 30°; B = 60° as an example, so F2 = 3F1, and the force is amplified by 3 times. If A = 15°; B = 75°, then F2 = 14F1.

[0080] Preferably, a limiting opening 5931 is provided on the input italic 593, and a limiting hemisphere 598 is fixed on the boosting frame 590 to cooperate with the limiting opening 5931. The limiting hemisphere 598 is located between the input italic 593 and the boosting frame 590, and the limiting hemisphere 598 is connected to the boosting frame 590 by a spring. After the input italic 593 moves forward, when the limiting opening 5931 moves to the position of the limiting hemisphere 598, the limiting hemisphere 598 can pop out under the elastic force of the spring, and the limiting hemisphere 598 can be stuck in the limiting opening 5931.

[0081] The coal sample collected in the storage pipe 560 needs to be detected by a detection device. The detection device includes a Roots vacuum pump 800. A vacuum thermocouple 810 is provided at the air inlet of the Roots vacuum pump 800. The air inlet of the Roots vacuum pump 800 is communicated with one end of a test pipeline 820. The other end of the test pipeline 820 is communicated with one end of a test pipeline 830. The other end of the test pipeline 830 is connected with a silica gel tube 840. The silica gel tube 840 is used to communicate with a needle valve 572 on the sealing rubber 571 of the storage pipe 560. A mass flow sensor 850 is provided at the connection of the test pipeline 820 and the test pipeline 830. A gas concentration sensor 860 is provided at the connection of the test pipeline 830 and the silica gel tube 840. The mass flow sensor 850 and the gas concentration sensor 860 are respectively communicated with a monitoring system 870.

[0082] The mass flow sensor 850 and the gas concentration sensor 860 are arranged on a test pipeline resistant to hydrogen sulfide gas corrosion, and the inner diameters of the test pipeline segments at the air inlet and air outlet ends of the mass flow sensor 850 are not less than 10 times and 5 times of the inner diameter of the test pipeline respectively; the test pipeline and the storage pipe 560 are placed in an air bath 880, and the temperature of the air bath 880 is the same as the temperature of the coal seam.

[0083] A direct test method for the harmful gas content of coal and rock strata based on the freezing sampling process, comprising the following steps:

[0084] S1: After connecting the three-wing concave bit 400, the sampling assembly 500 and the end drill pipe 100, connect them to the double-layer drill pipe 200. Then connect one end of the double-layer drill pipe 200 to the clamping device on the drill rig, and connect the end of the double-layer drill pipe 200 to the tail joint 300. Then connect the tail outer pipe interface 311 to one end of the tee 600 with the valve one 610 through a high-pressure rubber hose; connect the tail inner pipe interface 321 to one end of the tee 600 with the valve two 620 through a high-pressure rubber hose; connect one end of the tee 600 with the valve three 630 to the cold end pipe 710 of the vortex tube 700 through a high-pressure rubber hose, and connect the compressed air duct in the coal mine to the nozzle end 720 of the vortex tube 700 through a high-pressure rubber hose;

[0085] S2: Open the valve one 610, the valve two 620, and the valve three 630, and start the drill rig to rotate the three-wing concave bit 400, the sampling assembly 500, the end drill pipe 100, and the double-layer drill pipe 200, and cut the coal body. During this process, after the compressed air in the coal mine is cooled and separated by the vortex chamber of the vortex tube 700, the cold air enters one end of the tee 600 with the valve three 630 through the cold end pipe 710, and then is divided into the tail outer pipe interface 311 and the tail inner pipe interface 321 of the tail joint 300, and enters the annular space between the outer drill pipe 210 and the inner drill pipe 220 and the inner pipe of the drill pipe respectively; finally, it flows out from the annular space between the three-wing concave bit 400 and the spiral bit 522 and the annular space between the delivery pipe 510 and the built-in drill pipe 520, realizing the cooling of the three-wing concave bit 400 and the spiral bit 522 and discharging the coal slag;

[0086] S3: After drilling to a certain distance, the drilling can be stopped immediately, and the connection between the double-layer drill pipe 200 and the tail joint 300 can be removed. After adding a new double-layer drill pipe 200, connect the double-layer drill pipe 200 to the tail joint 300 again; repeat S2 - S3 until drilling to the predetermined sampling position;

[0087] S4: After drilling to the position for predetermined sampling, close valve two 620 and continue drilling. During this process, the coal chips cut by the spiral drill bit 522 will gradually enter the conveying pipe 510 through the spiral blade 521 and finally enter the storage pipe 560. After drilling a certain distance, turn off the compressed air source and remove the connection between the tail inner pipe interface 321 and the end of the tee 600 with valve two 620. Then, put the rubber ball 597 into the tail joint 300 through the tail inner pipe joint 321. Then, connect the tail inner pipe joint 321 to the end of the tee 600 with valve one 610 again through a high-pressure rubber hose and turn on the compressed air source, so that the rubber ball 597 enters the ball seat 596 of the sampling assembly 500 under the action of the cold air. The rubber ball 597 pushes the ball seat 596 under the action of the cold air, and the ball seat 596 drives the booster frame 590 to move. The booster frame 590 drives the sealing trigger rod 550, and the sealing trigger rod 550 drives the sealing actuator block 540 to move relatively to cut off the coal chips at the inlet of the storage pipe 560. At the same time, the sealing rubber 571 connected to the support frame 580 is pressed into the tail opening of the storage pipe 560 to seal the storage pipe 560. Then, the connection between the tail joint 300 and the double-layer drill pipe 200 can be removed, and the double-layer drill pipe 200, the sampling assembly 500, the end drill pipe 100, and the three-wing concave drill bit 400 can be gradually withdrawn from the borehole.

[0088] S5: Remove the sampling assembly 500 from the end drill pipe 100, then remove the conveying pipe 510 and the cylindrical positioning block 530, and disconnect the push rod 570 from the support frame 580. Connect the needle valve 572 integrated with the storage pipe 560 to the silica gel tube 840, then turn on the Roots vacuum pump 800. When the reading of the vacuum thermocouple 810 is less than 20, open the needle valve 572, and at the same time turn on the mass flow sensor 850, the gas concentration sensor 860, and the monitoring system 870 to record the flow rate of the gas flowing out of the storage pipe 560 and the concentration values of methane and hydrogen sulfide gases. Until the reading of the mass flow sensor 850 is 0 and the reading of the vacuum thermocouple 810 on the Roots vacuum pump 800 is less than 20, the Roots vacuum pump 800, the mass flow sensor 850, and the gas concentration sensor 860 can be turned off. The mass flow sensor 850 and the gas concentration sensor 860 are arranged on the test pipeline resistant to hydrogen sulfide gas corrosion, and the diameters of the test pipeline sections at the inlet and outlet ends of the mass flow sensor 850 are not less than 10 times and 5 times the diameters of the other parts of the test pipeline respectively. Further, the test pipeline and the storage pipe 560 are placed in the air bath 880, and the temperature of the air bath 880 is the same as the temperature of the coal seam.

[0089] S6: Then extract the gas flow rate and concentration data stored in the monitoring system 870, and define the gas flow rate data under standard conditions as q m 3 / s, methane concentration Hydrogen sulfide concentration Using the method of polynomial fitting in numerical analysis, the function of gas flow rate and time t is q(t), and the function of methane concentration and time t is The function of hydrogen sulfide concentration and time t is Then, the cumulative gas volume can be obtained by the method of definite integral as follows:

[0090]

[0091] In the formula: Q is the cumulative gas volume in the collected coal sample, m 3 ; t c is the pumping time of the Roots vacuum pump for the collected coal sample, s.

[0092] S7: Then take out the coal sample from the storage pipe 560, weigh it, and define it as M. Then the content of harmful gases in the coal seam is Q / M; the content of methane gas in the coal seam is The content of hydrogen sulfide gas in the coal seam is

[0093] The present invention proposes a direct test method for the content of harmful gases in coal and rock strata based on the freezing sampling process. By connecting the vortex tube 700 to the compressed air source in the coal mine to separate cold and hot air from the air, the separated cold air is used as the slag discharge medium during the drilling process, and at the same time, the coal body in front of the drill tool is cooled and frozen, so that the moisture in the coal body in front of the drill tool condenses into ice, thereby blocking the channels for the migration of gas and hydrogen sulfide gas in the coal body and preventing the escape of gas and hydrogen sulfide gas in the coal sample during the sampling process; by using the method of an internal spiral blade 521 and a storage pipe 560, the collection and storage of the coal sample during the sampling process are realized, and the sealing of the storage pipe 560 is achieved through the subsequent structure of the rubber ball 597 impacting the ball seat 596 and combining with pressure boosting conduction; the traditional method of collecting the escaped gas of the coal sample by the drainage method is abandoned. The coal sample in a constant temperature state is degassed by the Roots vacuum pump 800, and the online monitoring data of flow rate and concentration are further processed by the method of polynomial fitting to obtain the corresponding functions with time. Finally, the content of methane and hydrogen sulfide gas in the coal sample can be accurately obtained by the method of integration.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A direct test method for the content of harmful gases in coal and rock strata based on a freezing sampling process, characterized in that, It includes the following steps: S1: Install the three-wing concave drill bit (400) at the front end of the outer layer pipe (110) of the end part of the double-layer end drill pipe (100), install the sampling assembly (500) for taking coal samples at the front part of the inner layer pipe (120) of the end part of the end drill pipe (100), connect the rear end of the end drill pipe (100) to the inner and outer layer pipes of the double-layer drill pipe (200) correspondingly, then connect one end on the outside of the double-layer drill pipe (200) to the clamping device on the drilling rig, and connect the end of the double-layer drill pipe (200) to the tail joint (300); Connect the tail outer pipe interface (311) of the tail joint (300) and the tail inner pipe interface (321) of the tail joint (300) to the cold end pipe (710) of the vortex tube (700) respectively; Connect the compressed air duct in the coal mine to the nozzle end (720) of the vortex tube (700); S2: Start the drilling rig to cut the coal body; During this process, after the compressed air in the coal mine passes through the vortex chamber of the vortex tube (700) for cold and hot separation, the cold air enters the inner pipe space of the double-layer pipe and the space between the double-layer pipes respectively to cool the coal body and discharge the coal slag; S3: After drilling to a certain distance, stop drilling, remove the connection between the double-layer drill pipe (200) and the tail joint (300), add a new double-layer drill pipe (200) and then connect the double-layer drill pipe (200) to the tail joint (300); Repeat S2 - S3 until drilling to the predetermined sampling position; S4: After drilling to the predetermined sampling position, close the air inlet of the inner layer pipe of the double-layer drill pipe (200) and continue drilling. During this process, the sampling assembly (500) takes samples. After sampling, close the compressed air source and remove the connection between the tail inner pipe interface (321) and the vortex tube (700), then put the rubber ball (597) into the tail joint (300) through the tail inner pipe interface (321); Then connect the tail inner pipe interface (321) and one end of the vortex tube (700) through a high-pressure rubber hose again, and open the compressed air source, so that the rubber ball (597) enters the ball seat (596) of the sampling assembly (500) under the action of the cold air, and drives the sealing execution block (540) to cut off the coal chips at the inlet of the storage pipe (560). At the same time, the sealing rubber (571) connected to the support frame (580) is pressed into the rear end opening of the storage pipe (560) to seal the storage pipe (560); S5: Remove the sampling assembly (500) from the end drill pipe (100), take down the storage pipe (560), connect the needle valve (572) arranged on the storage pipe (560) to the silica gel pipe arranged on the test pipeline, and then turn on the Roots vacuum pump (800) to detect the coal sample.

2. The direct testing method for the content of harmful gases in coal and rock strata based on the freezing sampling process according to claim 1, wherein: The sampling assembly (500) mentioned in the steps includes a delivery pipe (510), an internal drill pipe (520) with spiral blades (521). The spiral blades (521) are fixed on the outer circumference of the internal drill pipe (520). The internal drill pipe (520) is placed inside the delivery pipe (510) and is coaxial with the delivery pipe (510). The tail end of the delivery pipe (510) is fixed to the front end of a cylindrical positioning block (530). The cylindrical positioning block (530) is fixed on the inner wall of the end inner layer pipe (120). A sealing execution block (540) is arranged behind the cylindrical positioning block (530). A sealing trigger rod (550) sequentially passes through the sealing execution block (540) and the cylindrical positioning block (530). A storage pipe (560) corresponding to the delivery pipe (510) is fixed behind the sealing execution block (540). A pressurization frame (590) provides power for the sealing trigger rod (550). The movement of the sealing trigger rod (550) can enable the sealing execution block (540) to seal the front end of the storage pipe (560).

3. A direct test method for the content of harmful gases in coal and rock strata based on a freezing sampling process according to claim 2, characterized in that: The sealing trigger rod (550) sequentially includes a trigger rod front part (551), a trigger part (552), and a trigger rod rear part (553) which are integrally designed from front to back. The trigger rod front part (551) is a horizontal rod. The tail end of the trigger rod front part (551) is integrally connected to the front end of the trigger part (552). The trigger part (552) is an inclined connecting rod. The rear end of the trigger part (552) inclines towards the axis of the end inner layer pipe (120). The trigger rod rear part (553) is a horizontal rod. The tail end of the trigger part (552) is integrally connected to the front end of the trigger rod rear part (553). The cross-section of the sealing trigger rod (550) is a rectangular surface. A trigger groove matching with the trigger part (552) is formed on the corresponding sealing execution block (540). The trigger groove includes a rectangular groove (542) vertically penetrating the sealing execution block (540). A front inclined groove (543) communicating with the rectangular groove (542) is arranged on one side of the front part of the rectangular groove (542) close to the outer wall of the sealing execution block (540). A rear inclined groove (544) communicating with the rectangular groove (542) is arranged on one side of the rear part of the rectangular groove (542) close to the semi-cylindrical block (541). The front inclined groove (543) and the rear inclined groove (544) are communicated. After the front inclined groove (543) and the rear inclined groove (544) are communicated, they cooperate with the trigger part (552).

4. The direct testing method for the content of harmful gases in coal and rock strata based on the freezing sampling process according to claim 2, characterized in that: The rear end of the sealing trigger rod (550) is fixedly connected through a support frame (580). A sealing rubber (571) is fixed on the side of the middle part of the support frame (580) facing the storage pipe (560). An opening is formed at the rear end of the storage pipe (560). The sealing rubber (571) cooperates with this opening and can block this opening. The front end of a push rod (570) is fixed on the rear end of the middle part of the support frame (580). The rear end of the push rod (570) is connected to an output inclined body (591) arranged inside the pressurization frame (590).

5. The direct test method for the content of harmful gases in coal and rock strata based on the freezing sampling process according to claim 4, characterized in that: Inside the supercharging frame (590), there are successively arranged a slidable output italic (591), a force-transmitting round block (592), and an input italic (593) from front to back. The rear end of the push rod (570) passes through the front frame of the supercharging frame (590) and then enters the inside of the supercharging frame (590) and is fixed on the front end face of the output italic (591). A first spring (573) is sleeved on the push rod (570) between the front end face of the output italic (591) and the opposite side wall of the supercharging frame (590). The rear end of the input italic (593) extends to the outside of the supercharging frame (590) and is provided with a limiting step (594) integrated with the input italic (593). A second spring (595) is arranged between the limiting step (594) and the rear side wall of the supercharging frame (590). A ball seat (596) with an opening facing backward is fixed on the rear side wall of the limiting step (594), and the ball seat (596) is matched with a rubber ball (597).

6. The direct test method for the harmful gas content of coal and rock strata based on the freezing sampling process according to claim 5, characterized in that: The side wall of the input italic (593) facing the force-transmitting round block (592) is an inclined surface, and the side wall of the output italic (591) facing the force-transmitting round block (592) is also an inclined surface. The included angle between the inclined surface of the input italic (593) and the horizontal plane is less than the included angle between the inclined surface of the output italic (591) and the horizontal plane.

7. The direct testing method for the content of harmful gases in coal and rock strata based on the freezing sampling process according to claim 1, wherein: In step S5, when the reading of the vacuum thermocouple gauge (810) of the waiting vacuum thermocouple gauge is less than 20, open the needle valve of the storage tube (560), and at the same time turn on the mass flow sensor (850), the gas concentration sensor (860), and the monitoring system (870), and record the flow rate of the gas flowing out of the storage tube (560) and the concentration values of methane and hydrogen sulfide gases; until the reading of the mass flow sensor (850) is 0, and the reading of the vacuum thermocouple gauge (810) on the roots vacuum pump (800) is less than 20, then the roots vacuum pump (800), the mass flow sensor (850), and the gas concentration sensor (860) can be turned off.

8. The direct test method for the content of harmful gases in coal and rock strata based on the freezing sampling process according to claim 7, characterized in that: The mass flow sensor (850) and the gas concentration sensor (860) are arranged on the test pipeline resistant to hydrogen sulfide gas corrosion, and the inner diameters of the test pipeline sections at the inlet and outlet ends of the mass flow sensor (850) are not less than 10 times and 5 times the inner diameter of the other sections of the test pipeline respectively.

9. The direct testing method for the harmful gas content of coal and rock strata based on the freezing sampling process according to claim 7, characterized in that: Including step S6, extracting the gas flow rate and concentration data stored in the monitoring system (870), defining the gas flow rate data under standard conditions as q , with the unit of m 3 / s, methane concentration %, hydrogen sulfide concentration %; Using the method of polynomial fitting in numerical analysis, the function of gas flow rate and time t is obtained as q (t), the function of methane concentration and time t is , and the function of hydrogen sulfide concentration and time t is ; Then, the cumulative gas volume can be obtained by the definite integral method as follows: In the formula: Q is the cumulative gas volume in the coal sample collected under standard conditions, m 3 ; t c is the time for the Roots vacuum pump (800) to evacuate the coal sample collected, s.

10. The direct test method for the content of harmful gases in coal and rock strata based on the freezing sampling process according to claim 9, characterized in that: Including step S7, after step S6, the coal sample is taken out from the storage pipe (560), and its weight is weighed and defined as M. Then, the content of harmful gases in the coal seam is Q / M ; the methane gas content in the coal seam is ; the hydrogen sulfide content in the coal seam is .

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