CN110031255B - Low-temperature negative pressure coal sample coal bed gas content fixed-point sampling system and sampling method - Google Patents
Low-temperature negative pressure coal sample coal bed gas content fixed-point sampling system and sampling method Download PDFInfo
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- CN110031255B CN110031255B CN201910398751.6A CN201910398751A CN110031255B CN 110031255 B CN110031255 B CN 110031255B CN 201910398751 A CN201910398751 A CN 201910398751A CN 110031255 B CN110031255 B CN 110031255B
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- 239000003245 coal Substances 0.000 title claims abstract description 125
- 238000005070 sampling Methods 0.000 title claims abstract description 78
- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000005553 drilling Methods 0.000 claims abstract description 56
- 239000002817 coal dust Substances 0.000 claims abstract description 25
- 230000007246 mechanism Effects 0.000 claims abstract description 17
- 230000008569 process Effects 0.000 claims description 9
- 238000007599 discharging Methods 0.000 claims description 8
- 238000000605 extraction Methods 0.000 claims description 5
- 238000009434 installation Methods 0.000 claims description 4
- 238000009825 accumulation Methods 0.000 claims description 3
- 230000009471 action Effects 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 3
- 238000005259 measurement Methods 0.000 abstract description 7
- 239000007789 gas Substances 0.000 description 41
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 16
- 238000001816 cooling Methods 0.000 description 8
- 239000007788 liquid Substances 0.000 description 8
- 229910052757 nitrogen Inorganic materials 0.000 description 8
- 238000003795 desorption Methods 0.000 description 5
- 238000011156 evaluation Methods 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 1
- 238000004868 gas analysis Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000010985 leather Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/16—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor using gaseous fluids
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/04—Devices for withdrawing samples in the solid state, e.g. by cutting
- G01N1/08—Devices for withdrawing samples in the solid state, e.g. by cutting involving an extracting tool, e.g. core bit
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Abstract
The invention discloses a fixed-point sampling system for gas content in a low-temperature negative-pressure coal sample coal bed, which comprises a pneumatic drilling machine, wherein the pneumatic drilling machine is provided with a hollow drill rod, the front end of the hollow drill rod is provided with a drill bit, an air compressor is connected with a vortex cold air mechanism through an air supply pipe, and the vortex cold air mechanism is communicated with the inner cavity of the hollow drill rod through an air supply pipe; an exhaust hood is arranged on the coal bed wall at the drilling point, and a hollow drill rod penetrates through a sliding sleeve in the exhaust hood; a first annular cavity is formed between the sliding sleeve and the inner wall of the exhaust hood; the exhaust hood is connected with an exhaust pipe, the exhaust pipe is connected with a sampling device, and the sampling device is connected with a negative pressure pump. The invention also discloses a sampling method. The invention has the advantages of high coal dust conveying efficiency and large sampling amount, can take out the coal dust at low temperature while drilling, has high sampling speed, avoids excessive gas release in the coal dust caused by normal-temperature sampling, also avoids excessive gas release in the coal dust caused by long sampling time, and improves the accuracy of coal seam gas content measurement.
Description
Technical Field
The invention relates to the technical field of coal mine gas content measurement, in particular to a system and a method for sampling coal samples.
Background
The coal-bed gas content is an important parameter in the related fields of coal-bed gas disaster prevention and control, coal-bed gas pre-extraction effect evaluation, coal-bed gas resource evaluation, development and the like, so that accurate measurement of the coal-bed gas content is an important precondition for guaranteeing the safe production of a coal mine.
Currently, coal seam gas content measuring methods commonly adopted in China include a geological prospecting desorption method, an indirect method and an underground natural desorption method. The following disadvantages mainly exist:
(1) The sampling time is long, and the gas loss is large in the sampling process. Because the gas loss is large, in the on-site desorption process, the measured gas desorption amount and desorption speed are smaller, so that the gas content measurement value is much lower than the actual value. The method not only affects the accuracy of coal mine gas hazard degree evaluation, but also affects the reliability of the subsequently selected gas disaster prevention measures.
(2) It is difficult to perform fixed-point sampling. The twist drill rod is used for sampling, so that serious mixing can be caused, and the coal sample sources are difficult to distinguish; the sampling chamber reversing drilling machine is arranged in the hollow drill rod for sampling, and although fixed-point sampling can be achieved, the sampling amount is too small; the coring bit can sample at fixed points, and the sampling amount is great, but sampling time is overlength, must influence the accuracy of coal seam gas content measurement.
In the device for researching negative pressure sampling, the domestic published patent document CN201310749625.3 discloses a fixed-point sampling method for the gas content of a negative pressure extraction type coal seam, which is simple to operate, short in sampling time and not sampling in a low-temperature environment; the published patent document CN201410074595.5 discloses a drilling negative pressure deslagging coal seam fixed-point sampling experiment system, which mainly provides a basis for the selection and optimization of sampling equipment by simulating the conveying condition of coal scraps during underground coal mine negative pressure sampling; the published patent document CN201811588701.6 discloses a negative pressure low temperature coal seam gas content measuring and sampling device which is difficult to adjust because liquid nitrogen is continuously injected for cooling.
If the coal sample is taken in a low-temperature environment, the loss of gas in the sampling process can be reduced, and the accuracy of measuring the gas content of the coal seam can be improved. Liquid nitrogen is sometimes used in operations such as fracturing coal beds in coal mines. If liquid nitrogen is used for the process of taking the coal samples in the coal seam, continuous injection of liquid nitrogen is needed for cooling, the corresponding structure and operation are complex, the cost is high, and once the leakage phenomenon occurs in the liquid nitrogen system, danger is brought to nearby personnel.
Disclosure of Invention
The invention aims to provide a fixed-point sampling system for the gas content of a low-temperature negative pressure coal sample coal bed, which is rapid in sampling, free from adopting liquid nitrogen for cooling, good in cooling effect and high in operation safety.
In order to achieve the purpose, the fixed-point sampling system for the gas content of the low-temperature negative pressure coal sample coal bed comprises a pneumatic drilling machine, wherein the pneumatic drilling machine is provided with a hollow drill rod, the front end of the hollow drill rod is provided with a drill bit, and the joint part of the hollow drill rod and the drill bit is provided with an air passage outlet;
the method is characterized in that: the air compressor is connected with a vortex cold air mechanism through an air supply pipe, the vortex cold air mechanism is provided with a total cold air outlet, the total cold air outlet is connected with an air supply pipe, and the air supply pipe is communicated with the inner cavity of the hollow drill rod; an exhaust hood is arranged on the coal bed wall at the drilling point, the inner wall of the exhaust hood is connected with a sliding sleeve through a connecting rod, and a hollow drill rod penetrates through the sliding sleeve and is in sliding fit with the sliding sleeve; a first annular cavity for passing the air flow carrying coal dust is formed between the sliding sleeve and the inner wall of the exhaust hood; an air supply valve is arranged on the air supply pipe;
the exhaust hood is connected with an exhaust pipe, the exhaust pipe is connected with a sampling device, and the sampling device is connected with a negative pressure pump through a connecting pipe.
The hollow drill rod is provided with an air supply hole at a position adjacent to the pneumatic drilling machine, an air supply cover is covered on the hollow drill rod at the air supply hole, the air supply cover is fixed on the ground through a bracket, and the air supply cover is rotationally connected with the hollow drill rod through a bearing; the air supply pipe is connected with the air supply cover and is communicated with the inner cavity of the hollow drill rod through the air supply cover and the air supply hole.
The number of the air supply holes is 3-5 along the circumferential direction of the hollow drill rod.
The vortex cold air mechanism comprises a plurality of vortex tubes which are connected in parallel, and each vortex tube is provided with a compressed air inlet, a hot air outlet and a cold air outlet; the compressed air inlets of the vortex tubes are respectively connected with the air supply pipes; the hot gas outlets of the vortex tubes are respectively connected with a hot gas discharge port through hot gas pipelines; the cold air outlets of the vortex tubes are respectively connected with the total cold air outlet through cold air pipelines.
The sampling device comprises a coal sample container, a transparent observation window is arranged in the middle of the coal sample container, and the cross-sectional area of the coal sample container is more than three times of that of the exhaust tube; the coal sample container is arranged in the box body, and the box body is supported on the ground through the support frame;
the bottom of the coal sample container is downwards connected with a discharging pipe, and a discharging valve is arranged on the discharging pipe; the upper part of one side of the coal sample container is connected with the exhaust pipe, the upper part of the other side of the coal sample container is connected with the connecting pipe, the connecting pipe is provided with the exhaust valve and the pressure gauge, and the joint of the connecting pipe and the coal sample container is provided with the filter screen.
The invention also discloses a sampling method by using the low-temperature negative pressure coal sample coal seam gas content fixed-point sampling system, which comprises the following steps:
the first step is an installation step, wherein a low-temperature negative pressure coal sample coal bed gas content fixed-point sampling system is installed at a selected coal bed position;
Pressing a drill bit at a selected coal seam drilling point, and mounting an exhaust hood on the coal seam wall;
the second step is drilling; starting the pneumatic drilling machine, and drilling at a drilling point; opening the air extraction valve and the negative pressure pump, and closing the discharge valve; the bore diameter of the drill hole is larger than the outer diameter of the hollow drill rod, and a second annular cavity for passing the air flow carrying coal dust is formed between the inner wall of the drill hole and the outer wall of the hollow drill rod;
Opening an air supply valve and an air compressor while drilling, enabling compressed air to enter compressed air inlets of vortex tubes in the vortex cold air mechanism through an air supply tube, enabling the compressed air to form hot air flow and cold air flow when passing through the vortex tubes, enabling the hot air flow to be discharged into the atmosphere after passing through a hot air pipeline and a hot air discharge port, and enabling the cold air flow to enter a second annular cavity through a cold air pipeline, a total cold air outlet, an air supply tube, a hollow drill rod and an air path outlet;
After entering the second annular cavity, under the action of the pressure and negative pressure of the cold air flow, coal dust formed when drilling is carried in the second annular cavity enters the first annular cavity in the exhaust hood, and then enters the coal sample container through the exhaust pipe; when the cold air flow passes through the coal sample container, the cross-sectional area of the coal sample container is more than three times of the cross-sectional area of the exhaust pipe, so that the speed of the cold air flow is reduced, and coal dust is deposited in the coal sample container; cold air flow enters the connecting pipe after passing through the filter screen and is discharged by the negative pressure pump;
The third step is sampling; when the drilling reaches the preset sampling depth, firstly closing the pneumatic drilling machine, the air compressor and the negative pressure pump, then opening the discharge valve to discharge the coal sample in the coal sample container, then closing the discharge valve, starting the pneumatic drilling machine, the air compressor and the negative pressure pump, and carrying the coal dust with the preset drilling depth into the coal sample container along the path in the second step by the cold air flow and accumulating;
The fourth step is to stop sampling; in the process of the third step, after a worker observes that the coal sample accumulation height reaches a preset height through the transparent observation window, the pneumatic drilling machine, the air compressor and the negative pressure pump are closed, the external coal sample tank is placed under the blanking pipe, the discharge valve is opened, so that the coal sample falls into the coal sample tank, and sampling is completed.
The invention has the following advantages:
The invention adopts the cold air generated by the vortex tube to realize low-temperature sampling, has large refrigerating capacity and rapid cold air generation, can realize rapid adjustment through the regulating valve at the hot air outlet of the vortex tube, and does not need moving parts and additional refrigeration sources in the process of generating cooling; negative pressure is generated by adopting a negative pressure pump to extract the coal sample, so that the sampling time is shortened, and the gas loss is reduced. The invention effectively improves the accuracy of coal seam gas content measurement, and the device is safe and reliable, easy to maintain, convenient for realizing fixed-point sampling and convenient for avoiding the phenomenon of mixing samples during sampling.
The parallel arrangement of the vortex tubes improves the ability of the present invention to generate cold air flow.
The invention has simple structure, the drill bit, the hollow drill rod and the coal dust are cooled by cold air generated by the vortex cold air mechanism in the drilling process, the cooling speed is high, the cooling efficiency is high, liquid nitrogen is not required to be transported underground, the danger caused by leakage of the liquid nitrogen is avoided, the safety degree is improved, the structure is simplified, and the installation speed and the working stability are improved.
According to the invention, the positive pressure of the cold air flow and the negative pressure generated by the negative pressure pump are used as power to drive the drilling coal dust to enter the coal sample container, so that the coal dust conveying efficiency is high, the coal dust can be taken out at low temperature while drilling, the sampling speed is greatly improved, excessive gas release in the coal dust caused by normal-temperature sampling is avoided, excessive gas release in the coal dust caused by long sampling time is avoided, the originality of gas content in the coal sample is greatly improved, two targets of short sampling time and large sampling amount are considered, the coal sample which is closer to the actual condition of the coal bed is provided for the coal sample gas analysis experiment, and the accuracy of coal bed gas content measurement is improved.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention;
FIG. 2 is an enlarged view at A in FIG. 1;
FIG. 3 is a schematic view of the vortex cooling mechanism of FIG. 1;
Fig. 4 is a schematic diagram of the sampling device of fig. 1.
Detailed Description
As shown in fig. 1 to 4, the fixed-point sampling system for the gas content of the low-temperature negative pressure coal sample coal bed comprises a pneumatic drilling machine 1, wherein a hollow drill rod 2 is arranged on the pneumatic drilling machine 1, a drill bit 3 is arranged at the front end of the hollow drill rod 2, an air passage outlet is arranged at the joint part of the hollow drill rod 2 and the drill bit 3 along the radial direction, and the air passage outlet is communicated with the inside and the outside of the hollow drill rod; the air passage outlet is of a through hole structure, which is not shown in the figure.
The air compressor 4 is connected with a vortex cold air mechanism 6 through an air supply pipe 5, the vortex cold air mechanism 6 is provided with a total cold air outlet 7, the total cold air outlet 7 is connected with an air supply pipe 8, and the air supply pipe 8 is communicated with the inner cavity of the hollow drill rod 2; an exhaust hood 9 is arranged on the coal seam wall 33 at the drilling point, the inner wall of the exhaust hood 9 is connected with a sliding sleeve 11 through a connecting rod 10, and the hollow drill rod 2 passes through the sliding sleeve 11 and is in sliding fit with the sliding sleeve 11; a first annular cavity 12 for passing the air flow carrying coal dust is formed between the sliding sleeve 11 and the inner wall of the exhaust hood 9; the blast pipe 5 is provided with a blast valve 13;
the exhaust hood 9 is connected with an exhaust pipe 14, the exhaust pipe 14 is connected with a sampling device, and the sampling device is connected with a negative pressure pump 16 through a connecting pipe 15. A sealing leather pad is arranged at the bearing of the exhaust hood 9.
The hollow drill rod 2 is provided with an air supply hole 17 at a position adjacent to the pneumatic drilling machine 1, an air supply cover 18 is covered on the hollow drill rod at the air supply hole 17, the air supply cover 18 is fixed on the ground through a bracket, and the air supply cover 18 is rotationally connected with the hollow drill rod 2 through a bearing; the air supply pipe 8 is connected with the air supply cover 18 and is communicated with the inner cavity of the hollow drill rod 2 through the air supply cover 18 and the air supply hole 17. A sealing gasket is arranged at the bearing between the air supply cover 18 and the hollow drill rod 2. The bearings, brackets and gaskets are conventional and are not shown.
The number of the air supply holes 17 is 3-5 (including two end values) evenly arranged along the circumferential direction of the hollow drill rod.
The vortex cold air mechanism 6 comprises a plurality of vortex tubes 19 connected in parallel, wherein the vortex tubes 19 are provided with a compressed air inlet 20, a hot air outlet 21 and a cold air outlet 22; the compressed air inlets 20 of the vortex tubes 19 are respectively connected with the air supply pipes 5; the hot gas outlet 21 of each vortex tube 19 is connected with a hot gas discharge port 24 through a hot gas pipeline 23 respectively; the cold air outlet 22 of each vortex tube 19 is connected with the total cold air outlet 7 through a cold air pipeline 35. A regulating valve is arranged at the hot gas outlet 21 of the vortex tube 19. The vortex tube 19 is a conventional device, and the specific structure is not described in detail, but the regulating valve is not shown. The parallel arrangement of the vortex tubes 19 enhances the ability of the present invention to generate a cold gas flow.
The sampling device comprises a coal sample container 25, a transparent observation window 26 is arranged in the middle of the coal sample container 25, the coal sample container 25 is big-end-up (in a funnel shape), and the average cross-sectional area (the area of a vertical cross section in the figure) of the coal sample container 25 is more than three times that of the exhaust tube 14; the coal sample container 25 is arranged in the box body 27, and the box body 27 is supported on the ground through a support frame;
The bottom of the coal sample container 25 is connected with a blanking pipe 28 downwards, and a discharging valve 29 is arranged on the blanking pipe 28; the upper part of one side of the coal sample container 25 is connected with the exhaust pipe 14, the upper part of the other side of the coal sample container 25 is connected with the connecting pipe 15, the connecting pipe 15 is provided with an exhaust valve 30 and a pressure gauge 31, and the joint of the connecting pipe 15 and the coal sample container 25 is provided with a filter screen. The filter screen is a conventional device, not shown.
The invention also discloses a sampling method by using the low-temperature negative pressure coal sample coal seam gas content fixed-point sampling system, which comprises the following steps:
the first step is an installation step, wherein a low-temperature negative pressure coal sample coal bed gas content fixed-point sampling system is installed at a selected coal bed position;
Connecting the drill bit 3 with the hollow drill rod 2, connecting the hollow drill rod 2 with the vortex cold air mechanism 6 through the air supply pipe 8, pressing the drill bit 3 at a selected coal seam drilling point, and installing the exhaust hood 9 on the coal seam wall 33;
the second step is drilling; starting the pneumatic drilling machine 1, and drilling holes at the drilling points; opening the extraction valve 30 and the negative pressure pump 16, and closing the discharge valve 29; the bore diameter of the drill hole is larger than the outer diameter of the hollow drill rod 2, and a second annular cavity 34 for passing the air flow carrying coal dust is formed between the inner wall of the drill hole and the outer wall of the hollow drill rod 2;
Simultaneously, the air supply valve 13 and the air compressor 4 are opened, compressed air enters the compressed air inlet 20 of each vortex tube 19 in the vortex air mechanism 6 through the air supply pipe 5, the compressed air forms hot air flow and cold air flow when passing through the vortex tubes 19, the hot air flow is discharged into the atmosphere after passing through the hot air pipeline 23 and the hot air discharge port 24, and the cold air flow enters the second annular cavity 34 through the cold air pipeline 35, the total cold air outlet 7, the air supply pipe 8, the hollow drill rod 2 and the air path outlet;
After entering the second annular cavity 34, under the action of the pressure and negative pressure of the cold air flow, coal dust formed when carrying drilling holes in the second annular cavity 34 enters the first annular cavity 12 in the exhaust hood 9 and then enters the coal sample container 25 through the exhaust pipe 14; when the cold air flow passes through the coal sample container 25, the speed of the cold air flow is reduced because the cross-sectional area of the coal sample container 25 is more than three times that of the exhaust pipe 14, and coal dust is deposited in the coal sample container 25; the cold air flow enters the connecting pipe 15 after passing through the filter screen and is discharged by the negative pressure pump 16;
the third step is sampling; when the drilling reaches the preset sampling depth, firstly closing the pneumatic drilling machine 1, the air compressor 4 and the negative pressure pump 16, then opening the discharge valve 29 to discharge the coal sample in the coal sample container 25, then closing the discharge valve 29, starting the pneumatic drilling machine 1, the air compressor 4 and the negative pressure pump 16, and carrying the coal dust with the preset drilling depth into the coal sample container 25 along the path in the second step by the cold air flow and accumulating;
The fourth step is to stop sampling; in the process of the third step, after the worker observes that the coal sample accumulation height reaches the preset height through the transparent observation window 26, the pneumatic drilling machine 1, the air compressor 4 and the negative pressure pump 16 are closed, an external coal sample tank is placed under the blanking pipe 28, the discharging valve 29 is opened, so that the coal sample falls into the coal sample tank, and sampling is completed.
After the sampling is completed, the fixed-point sampling system for the gas content of the low-temperature negative pressure coal sample coal bed is dismantled at the coal bed wall 33.
The above embodiments are only for illustrating the technical solution of the present invention, and it should be understood by those skilled in the art that although the present invention has been described in detail with reference to the above embodiments: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention, which is intended to be encompassed by the claims.
Claims (2)
1. The method for sampling by utilizing the low-temperature negative pressure coal sample coal seam gas content fixed-point sampling system comprises a pneumatic drilling machine, wherein the pneumatic drilling machine is provided with a hollow drill rod, the front end of the hollow drill rod is provided with a drill bit, and the joint part of the hollow drill rod and the drill bit is provided with an air passage outlet;
the method is characterized in that: the air compressor is connected with a vortex cold air mechanism through an air supply pipe, the vortex cold air mechanism is provided with a total cold air outlet, the total cold air outlet is connected with an air supply pipe, and the air supply pipe is communicated with the inner cavity of the hollow drill rod; an exhaust hood is arranged on the coal bed wall at the drilling point, the inner wall of the exhaust hood is connected with a sliding sleeve through a connecting rod, and a hollow drill rod penetrates through the sliding sleeve and is in sliding fit with the sliding sleeve; a first annular cavity for passing the air flow carrying coal dust is formed between the sliding sleeve and the inner wall of the exhaust hood; an air supply valve is arranged on the air supply pipe;
The exhaust hood is connected with an exhaust pipe, the exhaust pipe is connected with a sampling device, and the sampling device is connected with a negative pressure pump through a connecting pipe;
The hollow drill rod is provided with an air supply hole at a position adjacent to the pneumatic drilling machine, an air supply cover is covered on the hollow drill rod at the air supply hole, the air supply cover is fixed on the ground through a bracket, and the air supply cover is rotationally connected with the hollow drill rod through a bearing; the air supply pipe is connected with the air supply cover and is communicated with the inner cavity of the hollow drill rod through the air supply cover and the air supply hole;
The vortex cold air mechanism comprises a plurality of vortex tubes which are connected in parallel, and each vortex tube is provided with a compressed air inlet, a hot air outlet and a cold air outlet; the compressed air inlets of the vortex tubes are respectively connected with the air supply pipes; the hot gas outlets of the vortex tubes are respectively connected with a hot gas discharge port through hot gas pipelines; the cold air outlets of the vortex tubes are respectively connected with the total cold air outlet through cold air pipelines;
The sampling device comprises a coal sample container, a transparent observation window is arranged in the middle of the coal sample container, and the cross-sectional area of the coal sample container is more than three times of that of the exhaust tube; the coal sample container is arranged in the box body, and the box body is supported on the ground through the support frame;
The bottom of the coal sample container is downwards connected with a discharging pipe, and a discharging valve is arranged on the discharging pipe; the upper part of one side of the coal sample container is connected with the exhaust pipe, the upper part of the other side of the coal sample container is connected with a connecting pipe, an exhaust valve and a pressure gauge are arranged on the connecting pipe, and a filter screen is arranged at the joint of the connecting pipe and the coal sample container;
the method comprises the following steps:
the first step is an installation step, wherein a low-temperature negative pressure coal sample coal bed gas content fixed-point sampling system is installed at a selected coal bed position;
Pressing a drill bit at a selected coal seam drilling point, and mounting an exhaust hood on the coal seam wall;
the second step is drilling; starting the pneumatic drilling machine, and drilling at a drilling point; opening the air extraction valve and the negative pressure pump, and closing the discharge valve; the bore diameter of the drill hole is larger than the outer diameter of the hollow drill rod, and a second annular cavity for passing the air flow carrying coal dust is formed between the inner wall of the drill hole and the outer wall of the hollow drill rod;
Opening an air supply valve and an air compressor while drilling, enabling compressed air to enter compressed air inlets of vortex tubes in the vortex cold air mechanism through an air supply tube, enabling the compressed air to form hot air flow and cold air flow when passing through the vortex tubes, enabling the hot air flow to be discharged into the atmosphere after passing through a hot air pipeline and a hot air discharge port, and enabling the cold air flow to enter a second annular cavity through a cold air pipeline, a total cold air outlet, an air supply tube, a hollow drill rod and an air path outlet;
After entering the second annular cavity, under the action of the pressure and negative pressure of the cold air flow, coal dust formed when drilling is carried in the second annular cavity enters the first annular cavity in the exhaust hood, and then enters the coal sample container through the exhaust pipe; when the cold air flow passes through the coal sample container, the cross-sectional area of the coal sample container is more than three times of the cross-sectional area of the exhaust pipe, so that the speed of the cold air flow is reduced, and coal dust is deposited in the coal sample container; cold air flow enters the connecting pipe after passing through the filter screen and is discharged by the negative pressure pump;
The third step is sampling; when the drilling reaches the preset sampling depth, firstly closing the pneumatic drilling machine, the air compressor and the negative pressure pump, then opening the discharge valve to discharge the coal sample in the coal sample container, then closing the discharge valve, starting the pneumatic drilling machine, the air compressor and the negative pressure pump, and carrying the coal dust with the preset drilling depth into the coal sample container along the path in the second step by the cold air flow and accumulating;
The fourth step is to stop sampling; in the process of the third step, after a worker observes that the coal sample accumulation height reaches a preset height through the transparent observation window, the pneumatic drilling machine, the air compressor and the negative pressure pump are closed, the external coal sample tank is placed under the blanking pipe, the discharge valve is opened, so that the coal sample falls into the coal sample tank, and sampling is completed.
2. The method according to claim 1, characterized in that: the number of the air supply holes is 3-5 along the circumferential direction of the hollow drill rod.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110608928B (en) * | 2019-10-18 | 2024-07-30 | 重庆工程职业技术学院 | Gas collection device for coal exploitation |
| CN111042812A (en) * | 2020-01-13 | 2020-04-21 | 煤科集团沈阳研究院有限公司 | Underground fixed-point sampling device and method |
| CN111649979B (en) * | 2020-06-12 | 2021-07-16 | 中煤科工集团沈阳研究院有限公司 | Nitrogen low-temperature positive-pressure remote rapid gas content sampling device and method |
| CN113123822B (en) * | 2021-04-20 | 2023-03-14 | 焦作煤业（集团）新乡能源有限公司 | Regional coal receiving device that verifies of high mining height stope face |
| CN114235480B (en) * | 2021-12-21 | 2023-12-22 | 上海应用技术大学 | Negative pressure fixed-point sampling method for gas content in coal bed |
| CN114659828B (en) * | 2022-03-18 | 2022-12-20 | 河南理工大学 | Fixed point pressure maintaining sampling device for coal mine underground coal seam gas content determination |
| CN114592905B (en) * | 2022-04-27 | 2022-12-30 | 中国矿业大学 | Low-negative-pressure ejection deep hole continuous sampling system and sampling method |
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