Method for accurately regulating flow field in deep goaf

Abstract

The present application belongs to the technical field of mine fire and gas prevention and control, and particularly provides a method for precisely regulating and controlling deep flow field in goaf, wherein nitrogen injection pipelines and gas extraction pipelines are respectively laid along air intake roadway and air return roadway; a plurality of nitrogen injection branches are assembled on the nitrogen injection pipelines, and positive pressure remote control valves are assembled on the nitrogen injection branches; the ends of the positive pressure remote control valves are all provided with nitrogen injection pipes extending into coal body; the nitrogen injection branches and extraction branches are numbered; the control pipelines of the buried remote control valves are arranged at a position far away from the collapsed goaf, so as to solve the problem of deformation or line interruption of the control pipelines caused by the collapse of the goaf; under the condition of spontaneous combustion and gas collaborative prevention and control, the deep flow field in the goaf is precisely regulated and controlled, nitrogen injection and gas extraction in the deep goaf are effectively carried out, the possibility of spontaneous combustion in the deep goaf is reduced, and the safety of the working face is ensured.

Description

Technical Field

[0001] This invention belongs to the field of mine fire and gas prevention technology, and specifically provides a method for precise control of deep flow field in goaf areas. Background Technology

[0002] Mine gas and coal spontaneous combustion accidents seriously threaten coal mine safety, especially when spontaneous combustion and gas disasters coexist in the working face area, posing a dual threat to mine production and personnel safety. The goaf is a gas-solid two-phase system composed of a collapsed coal and rock mass and internal gases. All disasters in the goaf are conceived and developed during gas flow. Gas flow, the migration of different gas components, and heat exchange within the goaf are coupled together. Gas component migration and heat exchange all occur during gas flow, making gas flow the foundation and dominant factor of multi-field coupling in the goaf. Real-time control of gas flow within the goaf (including gas extraction and nitrogen injection) is the main means of dealing with various problems in the goaf, and controlling the flow field in the goaf is key to preventing spontaneous combustion and gas disasters.

[0003] Technical means to influence and control the flow field in the goaf include various forms of gas drainage, inert gas injection, and leak sealing. Among the various influencing factors, gas drainage has the greatest impact. Commonly used gas drainage measures include return air auxiliary roadways, high-level drainage roadways, bottom drainage roadways, tail roadways, high-level boreholes in the return air roadway, angled boreholes in roadways adjacent to the goaf, cross-layer boreholes in the goaf, upper corner buried pipe drainage measures, and integrated mining methods evolved according to actual conditions. Among these gas drainage measures, some measures have drainage locations relatively close to the working face, belonging to shallow goaf drainage, such as high-level boreholes in the return air roadway and upper corner buried pipe drainage measures, which mainly extract gas gushing towards the working face through interception. Some gas extraction measures are located far from the working face, belonging to deep extraction in the goaf, such as return air auxiliary roadways, tail roadways, high extraction roadways, bottom extraction roadways, and deep goaf drilling extraction measures. These measures mainly rely on the negative pressure at the extraction port to change the flow direction of gas in the goaf to achieve the purpose of gas extraction. Due to the uneven distribution of gas in the goaf, the gas concentration is higher at depth, making extraction in the goaf more efficient and effective in solving gas problems at the working face. Therefore, from the perspective of gas control, mines prefer to choose deep gas extraction. However, compared with shallow gas extraction in the goaf, deep extraction has a greater impact on the flow field of the goaf. The leakage routes formed by deep extraction are longer and deeper, and the area swept by the leakage airflow is larger, thus forming a large area of ​​spontaneous combustion hazard zone. In addition, deep gas extraction causes a significant reduction in the concentration of deep gas in the goaf, which reduces the inhibitory effect of gas on spontaneous combustion. Deep extraction, therefore, has a significant promoting effect on spontaneous combustion in the goaf.

[0004] Therefore, a significant technical factor contributing to the conflict between deep gas extraction in goaf areas and spontaneous combustion prevention is excessive gas extraction flow rate. Furthermore, the collapse of deep goaf areas may lead to deformation or interruption of control pipelines, making it impossible to adjust the extraction flow rate in a timely manner based on actual extraction results and spontaneous combustion warning information. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for precise control of the deep flow field in the goaf, wherein nitrogen injection pipelines and gas extraction pipelines are laid along the intake airway and return airway, respectively;

[0006] The nitrogen injection pipeline is equipped with multiple nitrogen injection branches, and each nitrogen injection branch is equipped with a positive pressure remote control valve. The end of each positive pressure remote control valve is equipped with a nitrogen injection pipe that extends into the coal body.

[0007] The gas extraction pipeline is equipped with multiple extraction branches, and each extraction branch is equipped with a negative pressure remote control valve. The end of each negative pressure remote control valve is equipped with an extraction pipe extending into the coal body.

[0008] Number the nitrogen injection branch and the extraction branch;

[0009] During construction, the coal mining equipment cuts the coal body along the direction of the working face. The area that the coal mining equipment passes through is the goaf. The area near the working face is preserved to maintain the normal operation of coal mining. The remaining goaf gradually collapses as the working face advances.

[0010] After the collapse of the goaf, all pipelines and valves were buried. The positive pressure remote control valves and negative pressure remote control valves were controlled through the compressed air pipeline.

[0011] As the working face continues to advance, after the buried extraction branch completes the gas extraction work in the area, the regulating valves of the compressed air pipeline and its corresponding branch are cut off.

[0012] Furthermore, the nitrogen injection branches are numbered K1, K2, ..., K m The extraction branches are numbered L1, L2, ..., L m ;

[0013] The span coefficient between the cylinder and the air intake is n;

[0014] K1=1, the cylinder of K1 is connected to K 1+n The air intake, K 1+n The cylinder is connected to K 1+2n The air intake, and so on, K m The cylinder is connected to K m+n The air intake;

[0015] Similarly, if L1=1, the cylinder of L1 is connected to L... 1+nThe air intake, L 1+n The cylinder is connected to L 1+2n The air intake, and so on L m The cylinder is connected to L m+n The air intake.

[0016] Furthermore, the nitrogen injection branch and the extraction branch are arranged in a one-to-one opposing configuration.

[0017] Furthermore, the pipeline assembly is inspected before construction to determine the connection status of the nitrogen injection pipeline, the gas extraction pipeline, and the remote control valves.

[0018] Furthermore, the nitrogen injection branch and the extraction branch use a unified numbering list, and the two are numbered alternately, with the nitrogen injection branch numbered with odd numbers and the extraction branch numbered with even numbers.

[0019] Further, the working face begins to advance. When the coal mining equipment passes through the No. 2 extraction branch and the No. 2 extraction branch is completely out of the working area of ​​the coal mining equipment, the No. 2 extraction branch is opened.

[0020] At the same time, nitrogen injection branch No. 1 is located on the opposite side of extraction branch No. 2. Nitrogen injection branch No. 1 is activated when it is completely separated from the working area of ​​the coal mining equipment.

[0021] Furthermore, as the working face continues to advance, when the No. 1 pipeline branch and the No. 2 extraction branch reach the maximum nitrogen injection length, the regulating valve corresponding to the No. 9 nitrogen injection branch is closed, the positive pressure remote control valve of the No. 1 pipeline branch is closed, and the nitrogen injection process of the No. 1 pipeline branch is completed.

[0022] At the same time, the regulating valve corresponding to the No. 10 extraction branch is closed, the negative pressure remote control valve of the No. 2 extraction branch is closed, and the gas extraction of the No. 2 extraction branch ends.

[0023] Furthermore, following this pattern, as the working face advances, the negative pressure remote control valves of extraction branches No. 4, 6, 8, ... are opened in sequence to extract gas from the corresponding locations;

[0024] Sequentially open the positive pressure remote control valves at pipeline branches 3, 5, 7, ... to inject nitrogen into the goaf for fire prevention.

[0025] Furthermore, the extraction pipes of nitrogen injection branches No. 3 and No. 5, and the extraction pipes of extraction branches No. 4 and No. 6, are all extended into goaf areas at different depths.

[0026] The beneficial effects of using this invention are:

[0027] The present invention arranges the control pipeline of the buried remote control valve in a location far away from the collapsed goaf, so as to solve the problem that the control pipeline may be deformed or the line may be interrupted during the collapse of the goaf.

[0028] Precise control of the deep flow field in the goaf under the condition of synergistic prevention and control of spontaneous combustion and gas effectively injects nitrogen and extracts gas in the deep goaf, reducing the possibility of spontaneous combustion in the deep goaf and ensuring the safety of the working face. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the present invention;

[0030] Figure 2 This is a schematic diagram of the pipeline control connection relationship in Embodiment 3 of the present invention;

[0031] Figure 3 This is a schematic diagram of the internal structure of the extraction branch.

[0032] Figure 4 This is a schematic diagram of the internal structure of the nitrogen injection branch;

[0033] Figure 5 A schematic diagram of a negative pressure remote control valve;

[0034] Figure 6 This is a schematic diagram of the internal structure of a negative pressure remote control valve.

[0035] Figure label:

[0036] a-Nitrogen injection pipeline; b-Gas extraction pipeline; Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings.

[0038] Example 1

[0039] Reference Figures 3-6 The remotely controlled valve includes a valve body, with an input flange connected to an extraction pipe and an output flange connected to a tee pipe.

[0040] The valve body includes a pipe body, a partition, a valve core, an elastic mechanism, and a cylinder. The partition is located in the middle of the inner cavity of the pipe body, dividing the inner cavity of the pipe body into an upper chamber and a lower chamber. A through hole is axially opened in the center of the partition. A filter screen is installed at the port of the upper chamber. The elastic mechanism is axially located inside the pipe body. The valve core is fixedly installed at the end of the elastic mechanism and is located inside the pipe body. The valve core abuts against the through hole to seal it.

[0041] The cylinder is axially located inside the tube body. The outer diameter of the cylinder is smaller than the through hole, and the output end of the cylinder passes through the through hole and abuts against the valve core. The air inlet is opened on the side wall of the tube body, and the inner side of the air inlet extends to the output port of the tube body through the pipeline.

[0042] The air inlet is connected to the external compressed air pipeline through a duct, and the cylinder and the air inlet are connected through an air supply pipe, which is located inside the tee pipe.

[0043] The other two ports of the tee pipe are connected to the external extraction pipeline;

[0044] A regulating valve is installed on the conduit;

[0045] Specifically, the two ends of the air supply pipe are an air inlet and an air outlet, respectively. The air inlet is connected to the air inlet nozzle, and the air outlet is connected to the cylinder.

[0046] The valve body, tee pipe and extraction pipe constitute an extraction unit. Multiple extraction units are set on one extraction pipeline. The extraction pipeline is laid along the roadway, and the cylinders and air inlets of each extraction unit are interlocked.

[0047] The partition is also equipped with a sampling nozzle, which is fitted with a one-way valve. The outlet of the gas supply pipe is branched off, which serves as a sampling port. The sampling port is connected to the sampling nozzle and a corresponding conduit to the gas supply pipe.

[0048] An annular groove is provided on the end face of the tube, and a bracket is embedded in the groove. The bracket consists of an annular frame and multiple mirror rods. One end of the multiple mirror rods is welded to the center of the annular frame, and the other end of the multiple mirror rods is welded to the inner wall of the annular frame.

[0049] Both the elastic mechanism and the cylinder are assembled onto the tube body via a bracket.

[0050] Specifically, two supports are stacked at the port of the upper chamber of the tube, the filter screen is placed between the two supports, and the elastic mechanism is coaxially fixed on the support.

[0051] A bracket is installed at the port of the lower chamber of the tube, and the cylinder is coaxially fixedly mounted on the bracket.

[0052] Specifically, there are two types of remotely controlled valves: positive pressure type and negative pressure type.

[0053] In this case, the cylinder and valve core of the positive pressure remote control valve are located inside the lower chamber;

[0054] The cylinder and valve core of the negative pressure remote control valve are located inside the upper chamber.

[0055] Example 2

[0056] Reference Figures 1-6 The method for precise control of the deep flow field in the goaf applies the remote control valve from Example 1. The specific scheme is as follows:

[0057] Nitrogen injection pipeline a and gas extraction pipeline b are laid along the intake airway and return airway, respectively.

[0058] Among them, nitrogen injection pipeline a, gas extraction pipeline b, extraction pipe and remote control valve are all made of high hardness materials, which can withstand the impact of rock mass when the roadway collapses.

[0059] The nitrogen injection pipeline a is equipped with multiple nitrogen injection branches, and positive pressure remote control valves are installed on the nitrogen injection branches. The ends of the positive pressure remote control valves are all equipped with nitrogen injection pipes that extend into the coal body.

[0060] Multiple extraction branches are installed on the gas extraction pipeline b. Negative pressure remote control valves are installed on the extraction branches. The ends of the negative pressure remote control valves are all equipped with extraction pipes that extend into the coal body.

[0061] Number the nitrogen injection branch and the extraction branch. The nitrogen injection branch is numbered K1, K2, ..., K m The extraction branches are numbered L1, L2, ..., L m ;

[0062] The span coefficient between the cylinder and the air intake is n;

[0063] K1=1, the cylinder of K1 is connected to K 1+n The air intake, K 1+n The cylinder is connected to K 1+2n The air intake, and so on, K m The cylinder is connected to K m+n The air intake;

[0064] Similarly, if L1=1, the cylinder of L1 is connected to L... 1+n The air intake, L 1+n The cylinder is connected to L 1+2n The air intake, and so on L m The cylinder is connected to L m+n The air intake;

[0065] The distance between two adjacent remotely controlled valves is Z (m), and the farthest stable control distance is nZ;

[0066] The advancing speed in the collapsed area is equal to the advancing speed V (m / h) of the working face. Based on data such as the gas concentration in the area, the cycle length T (h) of the buried remote control valve that needs to be precisely controlled can be estimated.

[0067] Based on the above parameters, the optimal span coefficient n required for the construction project can be easily derived.

[0068] During construction, the coal mining equipment cuts the coal body along the direction of the working face. The area that the coal mining equipment passes through is the goaf. The area near the working face is preserved to maintain the normal operation of coal mining. The remaining goaf gradually collapses as the working face advances.

[0069] After the collapse of the goaf, all pipelines and valves were buried. The positive pressure remote control valves and negative pressure remote control valves were controlled through the compressed air pipeline.

[0070] As the working face continues to advance, after the buried extraction branch completes the gas extraction work in the area, the regulating valves of the compressed air pipeline and its corresponding branch are cut off.

[0071] Specifically, depending on the actual working conditions, the span coefficient can be a variable, and when adjusting the span coefficient, a blank area is left on the pipeline.

[0072] The nitrogen injection branch and the extraction branch are arranged in a one-to-one opposing manner.

[0073] As the working face begins to advance, the nitrogen injection branch and the gas extraction branch that the coal mining equipment passes through are opened simultaneously. The nitrogen injection process of the nitrogen injection branch creates positive pressure on one side of the goaf, while the gas extraction process of the gas extraction branch creates negative pressure on the other side of the goaf, thus forming a deep flow field in the goaf.

[0074] The flow field increased the range and quantity of nitrogen injection through the low pressure on the return airway side of the goaf, thus enhancing the nitrogen injection effect. Similarly, the high pressure on the intake airway side of the goaf increased the range and quantity of deep gas drainage in the goaf, thus enhancing the gas drainage effect.

[0075] Example 3

[0076] Compared to Embodiment 2, the difference in this embodiment is as follows:

[0077] Reference Figures 1-6 Specifically, before construction, check the pipeline assembly to ensure that the nitrogen injection pipeline (a), the gas extraction pipeline (b), and the remote control valve are properly connected.

[0078] The nitrogen injection branch and the extraction branch use a unified numbering list, and the two are numbered alternately. The nitrogen injection branch is numbered with odd numbers (1, 3, 5, ...), and the extraction branch is numbered with even numbers (2, 4, 6, ...).

[0079] The span coefficient n=4. Considering that the nitrogen injection branch and the extraction branch use a unified numbering list, the actual connection number of the positive pressure remote control valve is d and d+2n, and the actual connection number of the negative pressure remote control valve is d+1 and d+1+2n.

[0080] Taking the No. 2 extraction branch as an example, when the working face begins to advance, when the coal mining equipment passes through the No. 2 extraction branch and the No. 2 extraction branch is completely separated from the working area of ​​the coal mining equipment, the negative pressure remote control valve of the No. 2 extraction branch is opened to extract the gas inside the goaf.

[0081] Specifically, the regulating valve corresponding to the No. 10 extraction branch is opened by controlling the compressed air pipeline, and the No. 2 extraction branch is connected to the gas extraction pipeline b. Since the gas extraction pipeline b is under negative pressure, the gas in the goaf enters the gas extraction pipeline b through the extraction pipeline, and the gas in the goaf is extracted.

[0082] As the working face continues to advance, when the No. 2 extraction branch reaches its maximum extraction length (when the coal mining equipment advances to the No. 10 extraction branch, before the No. 10 extraction branch is buried by the collapsed goaf), the regulating valve corresponding to the No. 10 extraction branch is closed, the negative pressure remote control valve of the No. 2 extraction branch is closed, and the gas extraction of the No. 2 extraction branch ends.

[0083] When the coal mining equipment passes through the No. 2 extraction branch, it also passes through the No. 1 nitrogen injection branch located on the opposite side of the No. 2 extraction branch. When the No. 1 nitrogen injection branch is completely separated from the working area of ​​the coal mining equipment, the positive pressure remote control valve of the No. 1 nitrogen injection branch is opened to inject inert gas into the goaf.

[0084] Specifically, the regulating valve corresponding to nitrogen injection branch No. 9 is opened by controlling the compressed air pipeline, and nitrogen injection branch No. 1 and nitrogen injection pipeline a are connected. The high-pressure inert gas (usually nitrogen) inside nitrogen injection pipeline a is injected into the corresponding area through nitrogen injection branch No. 1 to achieve the purpose of fire prevention and extinguishing in the goaf.

[0085] As the working face continues to advance, when the No. 1 pipeline branch reaches the maximum nitrogen injection length (the coal mining equipment advances to the No. 9 nitrogen injection branch, before the No. 9 nitrogen injection branch is buried by the collapsed goaf), the regulating valve corresponding to the No. 9 nitrogen injection branch is closed, the positive pressure remote control valve of the No. 1 pipeline branch is closed, and the nitrogen injection process of the No. 1 pipeline branch is completed.

[0086] Similarly, as the working face advances, the negative pressure remote control valves of extraction branches No. 4, 6, 8, ... are opened in sequence to extract gas from the corresponding locations;

[0087] Sequentially open the positive pressure remote control valves at pipeline branches 3, 5, 7, ... to inject nitrogen into the goaf for fire prevention.

[0088] Based on this, adjusting the opening degree of the regulating valve can control the output flow rate of the airflow and change the opening range of the corresponding negative pressure remote control valve, thereby achieving the purpose of adjusting the gas drainage rate of the extraction branch.

[0089] Preferably, the extraction pipes of nitrogen injection branches No. 3 and No. 5 extend into goaf areas at different depths, and the required nitrogen injection rates are also different. Therefore, they are controlled by regulating valves at nitrogen injection branches No. 11 and No. 13 respectively.

[0090] The extraction pipes of extraction branches No. 4 and No. 6 extend into goaf areas at different depths, requiring different gas extraction rates. Therefore, these rates are regulated by adjusting valves at extraction branches No. 12 and No. 14, respectively. This achieves effective control of the deep flow field in the goaf area.

[0091] Preferably, a gas composition detector is installed at the air inlet of the No. 9 nitrogen injection branch and the No. 10 extraction branch to detect and analyze the changes in gas composition in the deep goaf, thereby realizing the monitoring of gas changes inside the goaf.

[0092] Staff or the control system adjusts the flow field in real time based on monitoring results, creating a precisely controllable flow field deep within the goaf, effectively preventing fires from occurring inside the goaf.

[0093] The above content is only a preferred embodiment of the present invention. For those skilled in the art, many changes can be made in the specific implementation and application scope based on the concept of the present invention. As long as these changes do not depart from the concept of the present invention, they all fall within the protection scope of the present invention.

Claims

1. A method for precise control of deep flow field in goaf areas, characterized by: Nitrogen injection pipelines and gas extraction pipelines are laid along the intake airway and return airway, respectively. The nitrogen injection pipeline is equipped with multiple nitrogen injection branches, and each nitrogen injection branch is equipped with a positive pressure remote control valve. The end of each positive pressure remote control valve is equipped with a nitrogen injection pipe that extends into the coal body. The gas extraction pipeline is equipped with multiple extraction branches, and each extraction branch is equipped with a negative pressure remote control valve. The end of each negative pressure remote control valve is equipped with an extraction pipe extending into the coal body. Number the nitrogen injection branch and the extraction branch; During construction, the coal mining equipment cuts the coal body along the direction of the working face. The area that the coal mining equipment passes through is the goaf. The area near the working face is preserved to maintain the normal operation of coal mining. The remaining goaf gradually collapses as the working face advances. After the collapse of the goaf, all pipelines and valves were buried. The positive pressure remote control valves and negative pressure remote control valves were controlled through the compressed air pipeline. As the working face continues to advance, after the buried extraction branch completes the gas extraction work in the area, the regulating valves of the compressed air pipeline and its corresponding branch are cut off. The control valves of the nitrogen injection branch are numbered K1, K2, ..., K m The control valves of the extraction branch are numbered L1, L2, ..., L m ; The span coefficient between the cylinder and the air intake is n; K1=1, the cylinder of K1 is connected to K 1+n The air intake, K 1+n The cylinder is connected to K 1+2n The air intake, and so on, K m The cylinder is connected to K m+n The air intake; Similarly, if L1=1, the cylinder of L1 is connected to L... 1+n The air intake, L 1+n The cylinder is connected to L 1+2n The air intake, and so on L m The cylinder is connected to L m+n The air intake; Depending on the actual working conditions, the span coefficient can be a variable. When adjusting the span coefficient, a blank area should be left on the pipeline.

2. The method for precise control of deep flow field in goaf according to any one of claims 1, characterized in that: The nitrogen injection branch and the extraction branch are arranged in a one-to-one opposing configuration.

3. The method for precise control of deep flow field in goaf according to any one of claims 1, characterized in that: Before construction, inspect the pipeline assembly to determine the connection status of the nitrogen injection pipeline, gas extraction pipeline, and remote control valves.

4. The method for precise control of deep flow field in goaf areas according to claim 1, characterized in that: The nitrogen injection branch and the extraction branch use a unified numbering list, and the two are numbered alternately, with the nitrogen injection branch numbered with odd numbers and the extraction branch numbered with even numbers.

5. The method for precise control of deep flow field in goaf areas according to claim 4, characterized in that: The working face begins to advance. When the coal mining equipment passes through the No. 2 extraction branch and the No. 2 extraction branch enters the extraction range, the No. 2 extraction branch is opened. Meanwhile, nitrogen injection branch No. 1 is located on the opposite side of extraction branch No. 2, that is, on the air intake side of the goaf. When nitrogen injection branch No. 1 enters the nitrogen injection range, nitrogen injection branch No. 1 is activated.

6. The method for precise control of deep flow field in goaf areas according to claim 5, characterized in that: As the working face continues to advance, the depth to which the nitrogen injection branch and the extraction branch are buried in the goaf continues to increase. Based on the burial depth, the opening degree of the remote control valves of the nitrogen injection branch and the extraction branch is adjusted. The opening degree gradually decreases as the distance buried in the goaf increases. When the nitrogen injection branch reaches the maximum nitrogen injection depth range, close the regulating valve corresponding to the nitrogen injection branch, and the nitrogen injection of that nitrogen injection branch ends. When the extraction branch reaches the maximum extraction depth, the corresponding regulating valve of the extraction branch is closed, and the gas extraction of that extraction branch ends.

7. The method for precise control of deep flow field in goaf areas according to claim 6, characterized in that: Similarly, as the working face advances, the negative pressure remote control valves of extraction branches No. 4, 6, 8, ... are opened in sequence to extract gas from the corresponding locations; Sequentially open the positive pressure remote control valves at pipeline branches 3, 5, 7, ... to inject nitrogen into the goaf for fire prevention.

8. The method for precise control of deep flow field in goaf areas according to claim 4, characterized in that: The extraction pipes of nitrogen injection branches No. 3 and No. 5, and the extraction pipes of extraction branches No. 4 and No. 6, all extend into the goaf at different depths.

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