Thin coal seam along the long borehole extraction system and method

Abstract

The application discloses a thin coal seam bedding long borehole extraction system and method, relates to the technical field of coal mine borehole extraction, and comprises an in-hole structure, a first connecting pipe, a second connecting pipe, a third connecting pipe, a wind supply system, an extraction system and a residue and water drainage system. The in-hole structure comprises an extraction pipe and a blowing pipe lowered into a borehole. The blowing pipe is provided with an air outlet end inside the extraction pipe. The air inlet end of the blowing pipe is connected with the wind supply system through the first connecting pipe. The extraction pipe is connected with the extraction system through the second connecting pipe extending upwards of the borehole and is connected with the residue and water drainage system through the third connecting pipe extending downwards of the borehole. The application has the advantages of improving the separation effect of gas, water and residue and completely solving the problems of water accumulation in the extraction pipe and poor borehole in the borehole extraction process.

Description

Technical Field

[0001] This invention relates to the field of coal mine borehole extraction technology, and in particular to a system and method for extracting coal from thin coal seams by drilling long boreholes along the seam. Background Technology

[0002] When using long boreholes along the coal seam for drainage, coal dust and water accumulate inside the borehole, easily clogging the casing. To address this water accumulation problem, existing borehole drainage systems include drainage systems. For example, patent application CN202810933U discloses a downward borehole drainage system, comprising a sealing pipe, a drainage pipeline, a compressed air pipeline, and a drainer. The outlet of the compressed air pipeline is located inside the sealing pipe and extends to its lower part. The upper end of the sealing pipe is connected to the drainage pipeline, and the inlet of the drainer is connected to the drainage pipeline. Compressed air is supplied to the interior of the sealing pipe through the compressed air pipeline, blowing the water inside the borehole towards the opening of the sealing pipe. The negative pressure of the drainage pipeline extracts the water and gas blown out of the sealing pipe, and the water is discharged through the drainer. However, existing borehole drainage systems first extract gas and water simultaneously through the drainage pipeline, and then separate the water, resulting in poor separation of gas, water, and slag. In addition, in the past, long boreholes drilled along thin coal seams were prone to problems such as difficulty in sealing the boreholes and easy air leakage in the sealed sections. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a thin coal seam in-seam long borehole extraction system and method that improves the separation effect of gas, water and slag.

[0004] This invention solves the aforementioned technical problems through the following technical means: a long borehole extraction system for thin coal seams, comprising an internal structure, a first connecting pipe, a second connecting pipe, a third connecting pipe, an air supply system, an extraction system, and a slag and drainage system. The internal structure includes an extraction pipe and an air blowing pipe lowered into the borehole. The air outlet of the air blowing pipe is located inside the extraction pipe, and the air inlet of the air blowing pipe is connected to the air supply system through the first connecting pipe. The extraction pipe is connected to the extraction system through the second connecting pipe extending upwards from the borehole, and to the slag and drainage system through the third connecting pipe extending downwards from the borehole. Extracted gas enters the second connecting pipe, while accumulated water and coal dust enter the third connecting pipe under gravity, improving the separation effect of gas, water, and slag, and completely solving the problems of water accumulation in the extraction pipe and borehole obstruction during the extraction process.

[0005] As an optimized technical solution, the air supply system includes an air compressor and air supply pipelines. The air supply pipelines are connected to the air compressor, and the first connecting pipes of multiple boreholes are respectively connected to the air supply pipelines. A dedicated air compressor is installed, and the nitrogen injection and grouting pipeline system pre-installed in the roadway is used as the air supply pipeline to supply air separately to the drilling site. This ensures sufficient power for slag removal during drilling and tripping, effectively removing residual slag from the borehole, avoiding difficulties in casing installation caused by slag residue, and preventing clogging of the casing holes during extraction.

[0006] As an optimized technical solution, the extraction system includes an extraction trunk pipe and second connecting pipes for multiple boreholes that are respectively connected to the extraction trunk pipe.

[0007] As an optimized technical solution, the slag discharge and drainage system includes a slag discharge and drainage pipe, a slag discharger, and an automatic water discharger. Multiple drilled third connecting pipes are connected to the slag discharge and drainage pipe respectively. A slag discharge and drainage port is provided at certain intervals along the length of the slag discharge and drainage pipe. Each slag discharge and drainage port is connected to a slag discharger and an automatic water discharger in sequence.

[0008] As an optimized technical solution, the borehole structure also includes an outer plug, an inner plug, a grouting pipe, a return grout pipe, and a borehole connection device. The outer plug is sealed at the outer end of the sealing section of the borehole, and the inner plug is sealed at the inner end of the sealing section of the borehole. One end of the grouting pipe is located outside the borehole, and the other end is located between the outer plug and the inner plug. One end of the return grout pipe is located outside the borehole, and the other end is located between the outer plug and the inner plug. The borehole connection device passes through the outer plug and the inner plug, and the extraction pipe and the blowing pipe are both lowered into the borehole through the borehole connection device.

[0009] As an optimized technical solution, the orifice connection device includes an orifice pipe, a first connector, a second connector, a sealing pipe, and an elbow; the first connector is fixedly connected to the outer wall of the orifice pipe, and the second connector is fixedly connected to the first connector inside the orifice pipe; the sealing pipe and the elbow are respectively fixedly connected to both ends of the orifice pipe; the second connector enters the interior of the sealing pipe.

[0010] The orifice pipe passes through the outer plug, and the first connector and elbow are both located outside the borehole; the sealing pipe passes through the inner plug; the first connecting pipe is fixedly connected to the first connector, and the air inlet end of the blower pipe is fixedly connected to the second connector; the portion of the extraction pipe located in the sealing section enters the interior of the sealing pipe and the orifice pipe, and the elbow is connected to the second connecting pipe and the third connecting pipe respectively through a tee.

[0011] As an optimized technical solution, both the outer and inner plugs are made of polyurethane, and the internal structure also includes a polyurethane injection tube; one end of the polyurethane injection tube is located outside the borehole, and the other end is located at the polyurethane injection position of the inner plug. Using a polyurethane plug instead of a conventional bag-type borehole sealer addresses the issue of incomplete sealing caused by the bag-type sealer when the borehole diameter expands due to borehole collapse during drilling. The polyurethane plug ensures tight contact with the surrounding borehole.

[0012] The thin coal seam in-seam long borehole extraction method adopts a thin coal seam in-seam long borehole extraction system, including the following steps: during the extraction process of the borehole, the air supply system blows compressed air into the borehole at regular intervals, the extraction system provides negative pressure, the extraction gas enters the extraction system through the second connecting pipe, and the accumulated water and coal dust enter the slag discharge and drainage system through the third connecting pipe under the action of gravity.

[0013] As an optimized technical solution, the borehole structure also includes an outer plug, an inner plug, a sealing pipe, a grouting pipe, a return grout pipe, and a borehole connection device. The outer plug is sealed at the outer end of the sealing section of the borehole, and the inner plug is sealed at the inner end of the sealing section of the borehole. One end of the grouting pipe is located outside the borehole, and the other end is located between the outer plug and the inner plug. One end of the return grout pipe is located outside the borehole, and the other end is located between the outer plug and the inner plug. The borehole connection device passes through the outer plug and the inner plug, and the extraction pipe and the blowing pipe are both lowered into the borehole through the borehole connection device.

[0014] The method for extracting thin coal seams along the seam with long boreholes also includes the following steps: borehole sealing is carried out by intermittent, multiple pressurized grouting. The grouting material is quick-setting cement. Grout is injected into the borehole sealing section at regular intervals. The grouting pressure is gradually increased each time until the grouting pressure stabilizes at 2MPa and the grout can no longer be injected.

[0015] Compared with the traditional "two-blocking-one-injection" grouting method, intermittent multiple pressurized grouting improves the tightness of borehole sealing, increases the extraction concentration and service life of boreholes along the bedding plane, and lays the foundation for safe and efficient mining of the working face.

[0016] As an optimized technical solution, the method for extracting water from thin coal seams via long boreholes further includes the following steps: pre-grouting with bottled grout; immediately after grouting, performing simultaneous micro-extraction; and simultaneously observing the cement setting time and cement shrinkage ratio of the bottled grout. Extraction is then performed from the borehole after the cement has fully solidified. This simultaneous micro-extraction after grouting prevents gas leakage from the borehole, thus avoiding high gas concentrations in the roadway. By observing the bottled grout, extraction can be performed only after the cement has fully solidified, preventing the cement in the sealing section from being removed before solidification, which would affect the sealing effect.

[0017] The advantages of the invention are:

[0018] 1. Improved the separation effect of gas, water and slag, and completely solved the problems of water accumulation in the extraction pipe and poor drilling during the drilling extraction process.

[0019] 2. A dedicated air compressor is installed, and the nitrogen injection and grouting pipeline system pre-installed in the roadway is used as the air supply pipeline to supply air separately to the drilling site. This ensures the power for slag removal during drilling and the start-up process, effectively removes the residue in the hole, avoids the difficulty of casing installation caused by residue residue, and avoids the problem of easy blockage of the casing eye during the extraction process.

[0020] 3. Use polyurethane plugs instead of conventional bag sealers. When the diameter of the sealing section expands due to hole collapse during drilling, bag sealers will cause problems with incomplete sealing. Using polyurethane plugs can ensure tight contact with the surrounding area of ​​the borehole.

[0021] 4. Compared with the traditional "two-blocking-one-injection" grouting method, intermittent multiple pressurized grouting improves the tightness of borehole sealing, increases the extraction concentration and service life of boreholes along the bedding plane, and lays the foundation for safe and efficient mining of the working face.

[0022] 5. After grouting, the follow-up micro-extraction prevents gas from overflowing from the borehole and causing a high gas concentration in the roadway. By observing the bottled grout, the borehole can be extracted after the cement has completely solidified, preventing the cement in the sealing section from being extracted before it solidifies and affecting the sealing effect. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the internal structure of the hole in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure of the orifice connection device connecting the first connecting pipe, the second connecting pipe, and the third connecting pipe according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the thin coal seam in-seam long borehole extraction system according to an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] like Figure 1 As shown in the figure, an embodiment of the present invention discloses a long borehole extraction system for thin coal seams, including an internal structure, which includes an outer plug 1, an inner plug 2, a return grout pipe 3, an injection pipe 4, a polyurethane injection pipe 5, a borehole connection device 6, an extraction pipe 7, and a blower pipe 8.

[0028] The outer plug 1 is sealed at the outer end of the sealing section of borehole 9, and the inner plug 2 is sealed at the inner end of the sealing section of borehole 9. The designed length of borehole 9 is 110m, and the length of the sealing section is greater than or equal to 20m.

[0029] One end of the grouting pipe 4 is located outside the borehole, and the other end is located between the outer plug 1 and the inner plug 2; one end of the return grout pipe 3 is located outside the borehole, and the other end is located between the outer plug 1 and the inner plug 2.

[0030] One end of the polyurethane injection tube 5 is located outside the borehole, and the other end is located at the polyurethane injection position of the inner plug 2. Both the outer plug 1 and the inner plug 2 are made of polyurethane, replacing the conventional bag sealer. During the drilling process, when the borehole diameter expands due to borehole collapse, the bag sealer will cause the problem of incomplete sealing. Using a polyurethane plug can ensure tight contact with the borehole.

[0031] The orifice connection device 6 passes through the outer plug 1 and the inner plug 2. The extraction pipe 7 and the blowing pipe 8 are both lowered into the borehole through the orifice connection device 6. The extraction pipe 7 is a φ25mm PVC perforated pipe and is lowered into the bottom of the borehole 9. The blowing pipe 8 is a φ10mm PVC pipe with a length greater than or equal to 70m. The air outlet of the blowing pipe 8 is located inside the extraction pipe 7.

[0032] The orifice connection device 6 includes an orifice pipe 61, a first connector 62, a second connector 63, a sealing pipe 64, and an elbow 65. The orifice pipe 61 is made of φ50mm iron pipe, with one end being a 50mm to 40mm reducing interface. Both ends of the orifice pipe 61 are provided with external threads. The first connector 62 is fixedly connected to the outer wall of the orifice pipe 61, and the second connector 63 is fixedly connected to the first connector 62 inside the orifice pipe 61. The sealing pipe 64 and the elbow 65 are respectively fixedly connected to the two ends of the orifice pipe 61. The sealing pipe 64 is made of φ40mm PVC pipe and is screwed to the reducing interface end of the orifice pipe 61. The elbow 65 is made of φ50mm iron pipe. The second connector 63 enters the interior of the sealing pipe 64.

[0033] The orifice pipe 61 passes through the outer plug 1. The length of the orifice pipe 61 outside the borehole 9 is 150-200mm. The first connector 62 and the elbow 65 are both located outside the borehole 9. The sealing pipe 64 passes through the inner plug 2. The first connecting pipe 10 is fixedly connected to the first connector 62. The air inlet end of the blower pipe 8 is fixedly connected to the second connector 63. The part of the extraction pipe 7 located in the sealing section enters the interior of the sealing pipe 64 and the orifice pipe 61.

[0034] like Figure 2 As shown, the thin coal seam in-seam long borehole extraction system also includes a first connecting pipe 10, a second connecting pipe 11, a third connecting pipe 12, and an air supply system (not shown).

[0035] The air supply system includes an air compressor and an air supply pipeline. The air supply pipeline is connected to the air compressor. A dedicated air compressor is installed, and the nitrogen injection and grouting pipeline system pre-installed in the roadway is used as the air supply pipeline to supply air separately to the drilling site. This ensures the power for slag removal during the construction and drilling process of borehole 9, effectively removing residual slag from the hole and avoiding difficulties in casing installation caused by residual slag. It also avoids the problem of easy blockage of the casing eye during the extraction process. The first connecting pipes 10 of multiple boreholes 9 are respectively connected to the air supply pipeline. The air inlet of each blower pipe 8 is connected to the air supply pipeline in sequence through the second connector 63 and the first connecting pipe 10. During the extraction process, compressed air is blown into the hole through the blower pipe 8 to ensure that the extraction pipe 7 is not blocked by coal dust and to remove the water accumulated in the hole, ensuring that the borehole 9 is unobstructed.

[0036] Elbow 65 is connected to a second connecting pipe 11 extending upward to borehole 9 and a third connecting pipe 12 extending downward to borehole 9 via a tee. Both the second connecting pipe 11 and the third connecting pipe 12 are flexible hoses. The extraction gas entering elbow 65 from extraction pipe 7 enters the second connecting pipe 11, while water and coal dust enter the third connecting pipe 12 under the action of gravity.

[0037] like Figure 3 As shown, the thin coal seam in-seam long borehole extraction system also includes an extraction system and a slag discharge and drainage system. The extraction system includes an extraction main pipe 13, and the slag discharge and drainage system includes a slag discharge and drainage pipe 14, a slag discharger 15, and an automatic water discharger 16.

[0038] The extraction main pipe 13 is made of iron pipe. The extraction main pipe 13 is located above multiple boreholes 9. The second connecting pipes 11 of the multiple boreholes 9 are respectively connected to the extraction main pipe 13. Each extraction pipe 7 is connected to the extraction main pipe 13 in sequence through an elbow 65, a tee, and the second connecting pipe 11.

[0039] The slag discharge pipe 14 is made of φ50mm iron pipe. The slag discharge pipe 14 is located below multiple drill holes 9. The third connecting pipes 12 of multiple drill holes 9 are connected to the slag discharge pipe 14 respectively. Each extraction pipe 7 is connected to the slag discharge pipe 14 in sequence through elbow 65, tee and third connecting pipe 12. A slag discharge outlet is provided on the slag discharge pipe 14 every 150m along the length direction. Each slag discharge outlet is connected to a slag discharger 15 and an automatic water discharger 16 in sequence.

[0040] The various connection parts of the thin coal seam in-seam long borehole extraction system are reinforced with raw rubber tape, glass glue, and sealing glue. Each component of the thin coal seam in-seam long borehole extraction system must undergo an airtightness test before use to prevent air leakage.

[0041] This system truly achieves the separation of gas, water, and slag, improving the separation effect and completely solving the problems of water accumulation in the extraction pipe and blocked drilling during the extraction process.

[0042] This invention also discloses a method for extracting coal from thin coal seams using a long borehole system, comprising the following steps:

[0043] Step A: Before grouting, collect bottled grout in a mineral water bottle and hang it at the opening of borehole 9. After grouting, immediately perform a combined micro-extraction to prevent gas from overflowing from the borehole and causing a high gas concentration in the tunnel. The micro-extraction pressure should be such that gas does not overflow from the borehole opening, ensuring that the cement in the sealing section is not extracted before it solidifies. At the same time, observe the cement setting time and cement setting shrinkage ratio of the bottled grout. Generally, the cement grout water-cement ratio is 1:2, and it takes about 48 hours to solidify. After the cement has completely solidified, extract the borehole to prevent the cement in the sealing section from being extracted before it solidifies, which would affect the sealing effect.

[0044] Step B involves intermittent, multiple pressurized grouting for borehole sealing. Quick-setting cement is used as the grouting material. Grout is injected into the borehole sealing section at regular intervals, with the grouting pressure gradually increasing until it stabilizes at 2 MPa and no more grout can be injected. Compared to the traditional "two-plug-one-injection" grouting method, intermittent, multiple pressurized grouting improves the tightness of borehole sealing, increases the extraction concentration and service life of in-seam boreholes, and lays the foundation for safe and efficient mining at the working face.

[0045] In step C, during the extraction process of borehole 9, the air supply system blows compressed air into borehole 9 at regular intervals, the extraction system provides negative pressure, the extracted gas enters the extraction system through the second connecting pipe 11, and the accumulated water and coal powder enter the slag discharge and drainage system through the third connecting pipe 12.

[0046] This method was applied to 220 in-seam boreholes during the 1682(1) transport and flow construction. The maximum extraction concentration in the main pipe was 60%, the average extraction concentration was 45%, and the maximum extraction purity was 6.0 m³. 3 / min, average 2.8m 3 / min, with a purity of 1.27m³ per 100 holes. 3 / min, the longest extraction time in the borehole has reached 7 months, and the single-hole extraction concentration is still maintained above 35%.

[0047] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for extracting coal from thin coal seams using a long borehole system, comprising an in-hole structure, a first connecting pipe, a second connecting pipe, a third connecting pipe, an air supply system, an extraction system, and a slag and drainage system; the in-hole structure includes an extraction pipe and an air blowing pipe inserted into the borehole, the outlet of the air blowing pipe being located inside the extraction pipe, and the inlet of the air blowing pipe being connected to the air supply system via the first connecting pipe; the extraction pipe is connected to the extraction system via a second connecting pipe extending upwards from the borehole, and to the slag and drainage system via a third connecting pipe extending downwards from the borehole; the air supply system includes an air compressor and an air supply pipeline, the air supply pipeline being connected to the air compressor, and the first connecting pipes of multiple boreholes being respectively connected to the air supply pipeline; the extraction system includes an extraction main pipe, and the second connecting pipes of multiple boreholes being respectively connected to the extraction main pipe. The borehole includes a main pipe and a slag discharge system comprising a slag discharge pipe, a slag discharger, and an automatic water discharger. A third connecting pipe for multiple boreholes is connected to the slag discharge pipe. A slag discharge outlet is located at regular intervals along the length of the slag discharge pipe, and each outlet is sequentially connected to a slag discharger and an automatic water discharger. The borehole structure also includes an outer plug, an inner plug, a grouting pipe, a return grout pipe, and a borehole connection device. The outer plug seals the outer end of the sealed section of the borehole, and the inner plug seals the inner end of the sealed section. One end of the grouting pipe is located outside the borehole, and the other end is located between the outer plug and the inner plug. One end of the return grout pipe is located outside the borehole, and the other end is located between the outer plug and the inner plug. The borehole connection device passes through the outer plug and the inner plug. The extraction pipe and the blowing pipe are both lowered into the borehole through the borehole connection device. The method for extracting coal from thin coal seams using long boreholes along the seam includes the following steps: During the extraction process of the borehole, the air supply system blows compressed air into the borehole at regular intervals, the extraction system provides negative pressure, and the extracted gas enters the extraction system through the second connecting pipe. The accumulated water and coal dust enter the slag discharge and drainage system through the third connecting pipe under the action of gravity.

2. The method for extracting thin coal seams with long boreholes along the seam as described in claim 1, characterized in that: The orifice connection device includes an orifice tube, a first connector, a second connector, a sealing tube, and an elbow; the first connector is fixedly connected to the outer wall of the orifice tube, and the second connector is fixedly connected to the first connector inside the orifice tube; the sealing tube and the elbow are respectively fixedly connected to both ends of the orifice tube; the second connector enters the interior of the sealing tube. The orifice pipe passes through the outer plug, and the first joint and elbow are both located outside the borehole; the sealing pipe passes through the inner plug; the first connecting pipe is fixedly connected to the first joint, and the air inlet end of the blower pipe is fixedly connected to the second joint; the part of the extraction pipe located in the sealing section enters the interior of the sealing pipe and the orifice pipe, and the elbow is connected to the second connecting pipe and the third connecting pipe respectively through a tee.

3. The method for extracting thin coal seams with long boreholes along the seam as described in claim 1, characterized in that: Both the outer and inner plugs are made of polyurethane, and the internal structure also includes a polyurethane injection tube; one end of the polyurethane injection tube is located outside the borehole, and the other end is located at the polyurethane injection position of the inner plug.

4. The method for extracting thin coal seams with long boreholes along the seam as described in claim 1, characterized in that: The method for extracting thin coal seams along the seam with long boreholes also includes the following steps: borehole sealing is carried out by intermittent, multiple pressurized grouting. The grouting material is quick-setting cement. Grout is injected into the borehole sealing section at regular intervals. The grouting pressure is gradually increased each time until the grouting pressure stabilizes at 2MPa and the grout can no longer be injected.

5. The method for extracting thin coal seams with long boreholes along the seam as described in claim 4, characterized in that: The method for extracting thin coal seams by drilling long boreholes along the seam also includes the following steps: before grouting, bottled grout is collected; after grouting is completed, micro-extraction is carried out immediately, while observing the cement setting time and cement setting shrinkage ratio of the bottled grout; and extraction is carried out on the borehole after the cement has completely set.

Images