Roof water inrush control system and method based on physical and chemical modification of overlying rock strata in coal mines

Abstract

The present invention provides a roof water inrush control system and method based on the physical and chemical modification of the overlying rock strata in coal mines, comprising a high-pressure air pump, a refrigeration pipe, a refrigeration device, a heating pipe, a heating device, an air inlet sleeve, and an air outlet sleeve. The high-pressure air pump is installed in a coal mine tunnel and is connected to the refrigeration pipe and the heating pipe respectively through a tee pipe, and is used to pump cooled or heated air into the air inlet sleeve; the air inlet sleeve and the air outlet sleeve are distributed on both sides of the target layer, and the high-pressure air passes through the target layer from the air inlet sleeve via the refrigeration pipe and / or the heating pipe, and is discharged from the air outlet sleeve. The control system and method can cause the rock strata in the target layer to break up under the effects of cyclic cold and heat shock and weathering, breaking large blocks into small particles. The gaps between the broken granular rock layers are reduced and accumulated under the action of gravity to form a new waterproof layer, which increases the thickness of the water-proof layer in the overlying rock strata in the coal mine, achieving the purpose of effectively reducing the permeability of the rock strata.

Description

Technical Field

[0001] The present invention relates to the field of safe production in coal mines, and in particular to a system and method for controlling roof water inrush based on physical and chemical modification of overlying rock strata in coal mines. Background Art

[0002] Currently, coal still holds a dominant position in my country's energy structure. With the continuous development of the coal industry and the depletion of shallow coal seams, the hydrogeological conditions in coal mining areas have become more complex during deep coal seam mining operations, and coal mine safety issues have become increasingly prominent. Roof water inrush is a relatively common type of mine water inrush disaster. Some mines in central, eastern, and western my country have thick aquifers in their overlying rock strata, which have high water volume, high water pressure, and good recharge. Beneath these aquifers, due to the geological conditions of coal formation, are primarily shale and limestone layers. The limestone layer has numerous and large overburden fractures and a distinct network distribution. During coal mining, water from the upper aquifers penetrates these fractures and reaches the mining face, increasing the amount of water inrush and making it highly susceptible to mine water inrush accidents.

[0003] At present, the grouting process is commonly used to control water inrush from mine roofs. That is, by filling the cracks to block the water flow path, thereby reducing the probability of water inrush accidents. However, due to the complex geological structure of coal mines, the internal cracks are densely developed and distributed irregularly. Relying on existing survey technology, it is impossible to achieve a full-scale exploration of the distribution of cracks, resulting in some slurry being unable to enter, such as closed cracks and through cracks formed by external forces; at the same time, by reinforcing the surrounding rock through grouting, the mechanical properties of the fracture zone around the fault and the coal seam roof and floor damage zone are strengthened, which can increase the anti-seepage performance. However, the best application scenario of this method is to prevent the roof from having no water supply source during mining of the working face. For geological conditions where the water supply source of the aquifer is unknown and the water volume is large, grouting filling cannot achieve a good effect in preventing and controlling roof water inrush.

[0004] In summary, conventional water control devices and methods have certain defects and deficiencies in solving water control problems in coal mines with complex geological structures. Therefore, providing a water control method for coal mines with large water volumes and unknown water supply sources has important guiding and practical significance for reducing water inflow from working faces and improving mining efficiency. In coal mining areas, shale and limestone layers are easily crushed or pulverized, contain a large amount of clay minerals, and have weak resistance to weathering. Therefore, the present invention provides a roof water inrush control system and method based on the physical and chemical modification of the overlying rock strata in coal mines. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a roof water inrush control system and method based on the physical and chemical modification of the overlying rock strata in coal mines.

[0006] The technical solutions provided by the present invention are as follows:

[0007] A roof water inrush control system based on physical and chemical modification of overlying rock strata in coal mines is characterized by comprising a high-pressure air pump, a refrigeration pipe, a refrigeration device, a heating pipe, a heating device, an air inlet sleeve and an air outlet sleeve, wherein the high-pressure air pump is installed in a coal mine tunnel for pumping air, and the air outlet pipe of the high-pressure air pump is respectively connected to the refrigeration pipe and the heating pipe through a tee pipe; the two ends of the refrigeration pipe are respectively connected to the high-pressure air pump and the air inlet sleeve, and the two ends of the refrigeration pipe are respectively provided with a first valve and a second valve; the refrigeration device is used to cool and cool the air in the refrigeration pipe; the two ends of the heating pipe are respectively connected to the high-pressure air pump and the The air inlet sleeve and the third valve and the fourth valve are respectively provided at both ends of the heating pipe; the heating device is used to heat and increase the temperature of the air in the heating pipe; the air inlet sleeve and the air outlet sleeve are hollow cylindrical structures with both ends sealed, and the cylinder walls are both provided with air holes; an air inlet is provided at one end face of the air inlet sleeve, and an air outlet is provided at one end face of the air outlet sleeve; the air inlet sleeve is located in the transport tunnel, and the air outlet sleeve is located in the return air tunnel, and the air inlet sleeve and the air outlet sleeve are symmetrically installed on both sides of the target layer of the coal mine mining area; the air pumped out by the high-pressure air pump can pass through the refrigeration pipe and / or the heating pipe, and be ejected from the air outlet sleeve after passing through the target layer from the air inlet sleeve.

[0008] Furthermore, a gas control device is provided inside the air inlet sleeve and the air outlet sleeve, and the gas control device can control the opening and closing of the air holes of the air inlet sleeve and the air outlet sleeve.

[0009] Furthermore, the gas control device includes a limit plate, a spring, an air cylinder and an electric push rod. The limit plate is provided with a gas channel and is installed below the air cylinder. The spring is installed on the limit plate and connected to the air cylinder. The top of the air cylinder is sealed, a second air inlet is opened at the bottom, and adjustment holes corresponding to the air holes are opened around it. The electric push rod is arranged on the inner top surface of the air inlet sleeve and / or the air outlet sleeve, and its front end is fixedly connected to the air cylinder. When the air cylinder is extended or retracted to a certain stroke under the pulling of the electric push rod, the air hole can be closed or opened.

[0010] Furthermore, the system is also provided with a control system, which includes a computer, a PLC control cabinet, a first temperature sensor, a second temperature sensor, a third temperature sensor and a pressure sensor, wherein the first temperature sensor is installed on the refrigeration pipe, the second temperature sensor is installed on the heating pipe, the third temperature sensor is installed at the air outlet sleeve, and the pressure sensor is arranged at the air inlet sleeve; a first valve and a second valve are respectively provided at both ends of the refrigeration pipe, and a third valve and a fourth valve are respectively provided at both ends of the heating pipe; a first temperature sensor is provided on the refrigeration pipe near the air inlet sleeve, The heating pipe is provided with a second temperature sensor near the air inlet pipe, the air outlet sleeve is provided with a third temperature sensor, and the air inlet sleeve is provided with a pressure sensor; the high-pressure air pump, the first valve, the second valve, the third valve, the fourth valve, the first temperature sensor, the second temperature sensor, the third temperature sensor, the pressure sensor and the electric push rod are connected to the PLC control cabinet through a signal transmission line, which is used to transmit information to the PLC control cabinet and execute the operating instructions of the PLC control cabinet; the PLC control cabinet is connected to the computer through a signal transmission line, which is used to receive and transmit the operating instructions of the computer.

[0011] Furthermore, the refrigeration device includes a liquid nitrogen storage tank, a liquid nitrogen pump, a refrigeration sleeve and a liquid nitrogen recovery tank, wherein the refrigeration sleeve is an annular tube, and the refrigeration pipeline passes through the refrigeration sleeve along the axis; a liquid inlet hole and a liquid outlet hole are respectively provided at both ends of the refrigeration sleeve, and the liquid inlet hole is connected to the liquid nitrogen storage tank through the liquid nitrogen pump; the liquid outlet hole is connected to the liquid nitrogen recovery tank through a hose; after the liquid nitrogen pump is started, the liquid nitrogen is pumped out from the liquid nitrogen storage tank, and after the liquid nitrogen fills the refrigeration sleeve, it flows from the liquid hole to the liquid nitrogen recovery tank.

[0012] Furthermore, the heating device is an electromagnetic induction heater, which is provided with multiple sets of induction coils and can locally heat the heating pipe step by step.

[0013] Furthermore, the cooling pipe and the heating pipe are made of cast iron, and the cooling pipe and the heating pipe are provided with a heat insulation wrapping layer.

[0014] Furthermore, the system is also provided with a residual air water tank, and the air outlet of the air outlet sleeve is connected to the bottom of the residual air water tank through a hose.

[0015] A method for controlling roof water inrush based on physical and chemical modification of overlying strata in coal mines comprises the following steps:

[0016] S1, according to the air diffusion radius R, determine the area N of the advanced treatment area,

[0017] The diffusion coefficient D of air in the target layer of the mining operation area is calculated by the following formula (1):

[0018]

[0019] Where,

[0020] D—Diffusion coefficient under medium A and B conditions, m 2 / s,

[0021] α—correction coefficient,

[0022] v A —Flow rate of medium A, m / s,

[0023] T A —Pumping air temperature, K, T B —Target layer air temperature, K,

[0024] M A 、M B —Molar mass of gases A and B, kg / kmol,

[0025] ρ A , ρ B —Density of gases A and B, kg / m 3 ,

[0026] P A —Pumping air pressure, Pa, P B —Gas pressure in the target layer, Pa;

[0027] The effective diffusion radius R of the air ejected from the air inlet sleeve is calculated using the following formula (2):

[0028]

[0029] Where,

[0030] R—effective air diffusion radius, m,

[0031] D—Diffusion coefficient under medium A and B conditions, m 2 / s,

[0032] T A —Pumping air temperature, K, T B —Target layer air temperature, K,

[0033] Φ—rock porosity,

[0034] t—time, s;

[0035] The strike length l of the working face in the mining area is calculated using the following formula (3):

[0036] l=2nR (3)

[0037] Where,

[0038] l—working face length, m,

[0039] n—number of sleeves, pieces;

[0040] The area N of the advanced treatment area is calculated by the following formula (4):

[0041] N=lb (4)

[0042] Where,

[0043] N—area of ​​advanced treatment range, m 2 ,

[0044] b—the inclined length of the working face, m,

[0045] l—working face strike length, m;

[0046] S2: In the advanced treatment area, multiple hydraulic fracturing boreholes are opened parallel to the target layer, and the rock blocks of the target layer are pre-treated by hydraulic fracturing;

[0047] S3, within the scope of advanced governance,

[0048] In the middle of the section transport tunnel, multiple air intake holes are drilled vertically upward from the top plate at a certain distance. The depth of the air intake holes extends to a certain distance from the target layer.

[0049] Along the middle of the section return air channel, multiple air outlet channels are drilled vertically upward from the top plate at a certain distance. The depth of the air outlet channels extends to a certain distance from the target layer.

[0050] The air inlet and outlet holes are set on both sides of the target layer and are separated by a certain distance;

[0051] S4, installing the air inlet sleeve and the air outlet sleeve into the air inlet channel and the air outlet channel respectively, and fixing them;

[0052] S5, according to the actual geological conditions of the target layer, the minimum pump pressure P of the high-pressure air pump is determined by the following formula (5): min ,

[0053]

[0054] Where,

[0055] P1—air pressure under standard atmospheric pressure, Pa; P2—air pressure in the actual working surface, Pa,

[0056] F—pumping air pressure, KN,

[0057] S—sleeve port area, m 2 ,

[0058] K—correction coefficient;

[0059] S6, using the first temperature sensor, adjust the size of the refrigeration sleeve of the refrigeration device so that the temperature of the air flowing out of the refrigeration pipe is less than -50°C.

[0060] Use the second temperature sensor to adjust the number, position and operating power of the heating device coils so that the temperature of the air flowing out of the heating pipe is greater than 300°C.

[0061] According to the minimum pump outlet pressure P calculated in step S5 min , adjust the operating power of the high-pressure air pump so that the pump pressure of the high-pressure air pump P>P min ;

[0062] S7, using a PLC control cabinet, performs thermal shock cycles and weathering treatment on the target layer through the following steps:

[0063] S7-1, close the third valve and the fourth valve, close the air holes of the air inlet sleeve and the air outlet sleeve, and start the high-pressure air pump;

[0064] S7-2, opening the first valve and the second valve. When the pressure sensor reaches a set threshold, the air holes of the air intake sleeve are opened, and cold air is ejected outward from the air holes of the air intake sleeve.

[0065] S7-3, when the air temperature sensed by the third temperature sensor reaches a low temperature threshold, the air holes of the air outlet sleeve are opened, and air is ejected outward from the air holes of the air outlet sleeve, and the operation is maintained for a certain period of time;

[0066] S7-4, closing the first valve and the second valve to close the air holes of the air inlet sleeve and the air outlet sleeve;

[0067] S7-5, opening the third valve and the fourth valve. When the pressure sensor reaches the set threshold, the air holes of the air intake sleeve are opened, and hot air is ejected outward from the air holes of the air intake sleeve.

[0068] S7-6, when the air temperature sensed by the third temperature sensor reaches a high temperature threshold, the air holes of the air outlet sleeve are opened, and air is ejected outward from the air holes of the air outlet sleeve, and the operation is maintained for a certain period of time;

[0069] S7-7, repeat step S7-4 to complete the first round of hot and cold shock to the target layer;

[0070] S7-8, repeating steps S7-2 to S7-7 to complete the second round of hot and cold shocks; and performing N rounds of hot and cold shocks on the target layer in this order;

[0071] S7-9, turning off the cooling device and the heating device, opening all valves in this embodiment, and opening the air holes of the air inlet sleeve and the air outlet sleeve, and performing weathering treatment on the target layer for a certain period of time;

[0072] S8, the air outlet of the air outlet sleeve is connected to the bottom of the residual air water tank through a hose. The air discharged from the air outlet of the air outlet sleeve is heated or cooled in the residual air water tank and then discharged into the return air lane of the mine.

[0073] Furthermore, the spacing distances between the air inlet holes and the air outlet holes should be set based on the diffusion radius R of the air under low temperature conditions.

[0074] Beneficial effects of the present invention:

[0075] 1. The roof water inrush control system and method provided by the present invention causes the target rock layer to fragment under the cyclic effects of thermal shock and weathering, breaking large rock blocks into small particles. The crushed rock particles accumulate under the action of gravity, narrowing the gaps between the rock blocks and forming a new waterproof layer. This increases the thickness of the aquiclude and effectively reduces water permeability.

[0076] 2. The roof water inrush control system and method provided by the present invention will not destroy the original interlayer structure of the coal mining operation area, does not require crack survey of the target rock layer, and does not require the consumption of raw materials such as grouting fluid, which can save a lot of manpower and material resources.

[0077] 3. During the implementation of the operation, through advanced management, mining operations and prevention and control treatments are carried out simultaneously, which not only improves the safety of operations but also improves the efficiency of mining operations. In addition, no harmful substances that can pollute groundwater are introduced during the operation, which is pollution-free to the environment and in line with the concept of green development. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 : A schematic diagram of a vertical section of the construction area of ​​the present invention;

[0079] Figure 2 : A schematic top view of the construction area of ​​the present invention;

[0080] Figure 3 : Schematic diagram of the effects of the target layer before and after the thermal shock and weathering treatment of the present invention;

[0081] Figure 4 : Schematic diagram of the structure of the air intake cooling and heating device of the present invention;

[0082] Figure 5 : A schematic structural diagram of the air intake sleeve of the present invention;

[0083] Figure 6: A schematic structural diagram of the air outlet sleeve of the present invention;

[0084] Figure 7 : A schematic structural diagram of the gas cylinder adjustment hole and the gas hole A of the gas inlet sleeve of the gas control device 6 according to one embodiment of the present invention when they are fully opened;

[0085] Figure 8 : A schematic structural diagram of a gas control device 6 according to an embodiment of the present invention when the adjustment hole of the gas cylinder and the gas hole A of the gas inlet sleeve are completely closed;

[0086] Figure 9 : Figure 7 or Figure 8 Schematic diagram of the cross-sectional structure;

[0087] Figure 10 : A schematic diagram of the structure of an embodiment of the present invention, in which the gas control device 6 is provided with an electric push rod to control the air hole A of the air intake sleeve to be fully opened;

[0088] Figure 11 : A schematic diagram of the structure of an embodiment of the present invention, in which the gas control device 6 is provided with an electric push rod to control the air hole A of the air intake sleeve to be fully closed;

[0089] Figure 12-14 This is a schematic diagram of the structural state of controlling the air hole A of the air intake sleeve from closed to open when the gas control device 6 is provided with a motor in one embodiment of the present invention.

[0090] Explanation of symbols

[0091] 1- High-pressure air pump, 2- Refrigeration pipe, 3- Heating pipe, 4- Inlet sleeve, 41- Inlet port, 42- Air hole A, 5- Outlet sleeve, 51- Outlet port, 52- Air hole B, 6- Gas control device, 61- Limit plate, 62- Spring, 63- Cylinder,

[0092] 64-adjustment hole, 65-second air inlet, 66-electric push rod, 67-motor, 7-first valve, 8-second valve, 9-liquid nitrogen storage tank, 10-liquid nitrogen pump, 11-refrigeration sleeve, 12-liquid nitrogen recovery tank, 13-electromagnetic induction heater, 14-third valve, 15-fourth valve, 16-hydraulic support. DETAILED DESCRIPTION

[0093] The present invention will be described in detail below by way of embodiments with reference to the accompanying drawings.

[0094] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the present invention shall be as defined in the attached claims.

[0095] As attached Figure 1 To the attached Figure 6 As shown, a roof water inrush control system based on physical and chemical modification of overlying rock strata in coal mines includes a high-pressure air pump 1, a refrigeration pipe 2, a refrigeration device, a heating pipe 3, a heating device, an air inlet sleeve 4 and an air outlet sleeve 5.

[0096] A high-pressure air pump 1 is installed in a coal mine tunnel for pumping air. Air of different pressures can be pumped out by varying its operating power. An outlet pipe of the high-pressure air pump 1 is connected to a cooling pipe 2 and a heating pipe 3 via a tee pipe.

[0097] The two ends of the refrigeration pipe 2 are respectively connected to the high-pressure air pump 1 and the air inlet sleeve 4, which is used to transfer the air pumped out by the high-pressure air pump 1 and passing through it to the air inlet sleeve 4. At both ends of the refrigeration pipe 2, near the high-pressure air pump 1 and the air inlet sleeve 4, a first valve 7 and a second valve 8 are respectively provided to control the circulation of air in the refrigeration pipe 2.

[0098] The refrigeration device includes a liquid nitrogen storage tank 9 , a liquid nitrogen pump 10 , a refrigeration sleeve 11 and a liquid nitrogen recovery tank 12 .

[0099] The refrigeration sleeve 11 is an annular tube, and the refrigeration pipe 2 passes through the refrigeration sleeve 11 along the axis, that is, the refrigeration sleeve 11 wraps a length of the refrigeration pipe 2. In order to obtain a better refrigeration effect, the inner diameter of the refrigeration sleeve 11 is slightly larger than the outer diameter of the refrigeration pipe 2. A liquid inlet and a liquid outlet are respectively provided at both ends of the refrigeration sleeve 11. The liquid inlet is connected to the liquid nitrogen storage tank 9 through the liquid nitrogen pump 10, and the liquid outlet is connected to the liquid nitrogen recovery tank 12 through a hose. After the liquid nitrogen pump 10 is started, the liquid nitrogen is pumped out from the liquid nitrogen storage tank 9 and a certain liquid nitrogen flow rate is maintained; after the liquid nitrogen fills the refrigeration sleeve 11, it flows from the liquid outlet to the liquid nitrogen recovery tank 12. The liquid nitrogen recovery tank 12 is provided with an air outlet for discharging nitrogen.

[0100] The diameter and length of the refrigeration sleeve 11 can be adjusted according to actual production needs. According to common sense, the longer the length of the refrigeration sleeve 11 is, the larger the outer diameter of the sleeve is, the larger the sleeve volume is, the larger the volume of liquid nitrogen flowing through it is, and the greater the cooling effect on the air inside the refrigeration pipe 2 is.

[0101] The heating pipe 3 is connected to the high-pressure air pump 1 and the air intake sleeve 4 at both ends, respectively, for transferring the air pumped out of the high-pressure air pump 1 and passing through it to the air intake sleeve 4. A third valve 14 and a fourth valve 15 are respectively installed at both ends of the heating pipe 3, near the high-pressure air pump 1 and the air intake sleeve 4, for controlling the flow of air in the heating pipe 3.

[0102] The heating device is an electromagnetic induction heater 13 , which is configured with multiple sets of induction coils along the heating pipe 3 , thereby locally heating the heating pipe 3 step by step, thereby heating the air passing through the heating pipe 3 .

[0103] To facilitate connection, the heating pipe 3 and the cooling pipe 2 are connected to the air inlet sleeve 4 through a tee pipe.

[0104] To ensure operational safety,

[0105] The cooling pipe 2 and the heating pipe 3 need to be set at a certain distance;

[0106] The refrigeration device and the heating device need to be installed at a certain distance;

[0107] The cooling pipe 2 and the heating pipe 3 are made of cast iron. Furthermore, they can also be made of other metal materials with better mechanical properties and mechanical strength.

[0108] The cooling pipe 2 and the heating pipe 3 are wrapped with heat-insulating cotton. Furthermore, other materials with heat-insulating effects can also be used to make the heat-insulating wrapping layer.

[0109] like Figure 5 As shown, the air intake sleeve 4 is a hollow, sealed cylinder with an air intake port 41 extending through its bottom end surface and multiple air holes A42 formed in its sidewall near the top. Air pumped by the high-pressure air pump 1 flows through the cooling pipe 2 or heating pipe 3, enters the air intake sleeve 4 through the air intake port 41, and is ejected outward through the air holes A42.

[0110] like Figure 6 As shown, outlet sleeve 5, like outlet sleeve 4, is a hollow, sealed cylinder with an outlet port 51 extending through its bottom end, and multiple air holes B52 are formed in its sidewall near the top. High-pressure air is ejected from air holes A42, passes through the target layer, and accumulates in the drilled hole where outlet sleeve 5 is located. It then enters outlet sleeve 5 through air holes B52 and flows out through outlet port 51.

[0111] like Figure 7-9 As shown, in order to further control the circulation of air in the air intake sleeve 4 , a gas control device 6 is provided in the air intake sleeve 4 .

[0112] like Figure 7-8 As shown, in one embodiment, the gas control device 6 includes a limit plate 61, a spring 62, and an air cylinder 63. The air cylinder 63 is sealed at the top, with adjustment holes 64 corresponding to the air hole A42 formed around its periphery. A second air inlet 65 is formed at the bottom. At least one limit plate 61 is provided, and the limit plate 61 installed below the air cylinder 63 is provided with a gas passage. The spring 62 is installed between the limit plate 61 and the air cylinder 63 and / or between the end wall of the air intake sleeve 4 and the air cylinder 63. When high-pressure air enters the air intake sleeve 4, it flows into the air cylinder 63 from the second air inlet 65. Under the air pressure, the air cylinder 63 slides along the inner wall of the air intake sleeve 4, causing the adjustment hole 64 to be misaligned with the air hole A42, prompting the high-pressure air to flow out from the air hole A42. In this embodiment, the provision of the spring 62 can buffer the operation of the air cylinder 63 and utilize the automatic reset function of the spring 62 to automatically reset the air cylinder 63 in the absence of high-pressure airflow.

[0113] like Figure 9 As shown, in order to make the air cylinder 63 more stable when moving, in another embodiment, the outer peripheral surface of the air cylinder 63 and the inner wall of the air intake sleeve 4 are correspondingly provided with guide structures, such as a guide groove and a protrusion slidably fitted with the guide groove.

[0114] like Figure 10-11 As shown, in order to further control the circulation of air in the air inlet sleeve 4 and the air outlet sleeve 5, a gas control device 6 is provided in the air inlet sleeve 4 and the air outlet sleeve 5, and the gas control device 6 is improved. In this embodiment, specifically, the gas control device 6 also includes an electric push rod 66. The electric push rod is provided on the internal top surface of the air inlet sleeve 4 and the air outlet sleeve 5, and its front end is fixedly connected to the air cylinder 63. The electric push rod 66 operates by controlling the built-in drive motor to complete the extension and contraction operation of the set stroke. The electric push rod 66 is provided in the gas control device 6, which can further accurately control the operating stroke and operating time of the air cylinder 63, avoid the operation delay of the air cylinder 63 under the action of air pressure, and other operating obstacles, and effectively control the operating path of the air. At the same time, the spring 62 can also play a buffering role. In this embodiment, the spring 62 can be omitted according to actual usage.

[0115] The gas cylinder 63 can be made of silicone, which can withstand both high and low temperatures. Furthermore, when the gas cylinder 63 is retracted to a set stroke by the electric push rod 66, the gas holes A42 and B52 are fully closed. When the gas cylinder 63 is extended and retracted to a set stroke by the electric push rod 66, the gas holes A42 and B52 are fully opened. Because the gas control device 6 of the inlet sleeve 4 and the outlet sleeve 5 are identical in this embodiment, the assembly diagram of the outlet sleeve 5 and the gas control device 6 has been omitted.

[0116] like Figure 12-14 As shown, the present invention also provides an embodiment in which the electric push rod 66 is replaced with a motor 67. The torque generated by the rotation of the motor 67 is used to control the rotation of the air cylinder 63 to a certain angle, thereby opening or closing the adjustment hole 64 and the air hole A42 or the air hole B52 on the air cylinder 63. In this embodiment, the outer periphery of the air cylinder 63 and the inner walls of the air inlet sleeve 4 and the air outlet sleeve 5 are provided with corresponding guide structures, specifically corresponding circumferential grooves and protrusions. Because the gas control device 6 of the air inlet sleeve 4 and the air outlet sleeve 5 is the same in this embodiment, the schematic diagram of the assembly structure of the air outlet sleeve 5 and the gas control device 6 is omitted.

[0117] The roof water inrush treatment system of the present invention is further provided with a control system, which includes a computer, a PLC control cabinet, a first temperature sensor, a second temperature sensor, a third temperature sensor and a pressure sensor.

[0118] in,

[0119] The first temperature sensor is installed on the refrigeration pipe 2 and is arranged close to the air inlet sleeve 4 to measure the temperature of the cold air entering the air inlet sleeve 4;

[0120] The second temperature sensor is installed on the heating pipe 3 and is arranged close to the air intake sleeve 4 to measure the temperature of the hot air entering the air intake sleeve 4;

[0121] The third temperature sensor is installed at the air outlet sleeve 5 and is used to measure the temperature of the air entering the air outlet sleeve 5;

[0122] The pressure sensor is arranged at the air intake sleeve 4 and is used to measure the air pressure inside the air intake sleeve 4 .

[0123] The high-pressure air pump 1, the first valve 7, the second valve 8, the third valve 14, the fourth valve 15, the first temperature sensor, the second temperature sensor, the third temperature sensor, the pressure sensor and the electric push rod 66 are connected to the PLC control cabinet through a signal transmission line, and are used to transmit information to the PLC control cabinet and execute the operating instructions of the PLC control cabinet; the PLC control cabinet is connected to the computer through a signal transmission line, and is used to receive and transmit the operating instructions of the computer.

[0124] The PLC control cabinet controls the valves, temperature sensors, pressure sensors and electric push rod 66 mentioned above through the following logical sequence:

[0125] S1, close the third valve 14 and the fourth valve 15, drive the air cylinder 63 through the electric push rod 66 to close the air hole A42 and the air hole B52, and start the high-pressure air pump 1;

[0126] S2, open the first valve 7 and the second valve 8. When the pressure sensor reaches the set threshold, the electric push rod 66 drives the air cylinder 63 forward, and the cold air is ejected outward from the air hole A42 of the air intake sleeve 4;

[0127] S3: When the air temperature sensed by the third temperature sensor reaches the low-temperature threshold, the electric push rod 66 drives the air cylinder 63 forward, and air is ejected outward from the air hole B52 of the air outlet sleeve 5 for a certain operating time. The operating time should be sufficient to reduce the rock temperature of the target layer to a temperature close to the set low-temperature threshold. Therefore, it should be ≥ 8 hours. As a solution that takes both functionality and economy into consideration, the preferred operating time is 12 hours. During on-site operations, the operating time can also be appropriately extended or shortened based on comprehensive considerations such as the ambient temperature and ground temperature during the operation.

[0128] S4, close the first valve 7 and the second valve 8, and drive the air cylinder 63 to close the air hole A42 and the air hole B52 through the electric push rod 66;

[0129] S5, open the third valve 14 and the fourth valve 15. When the pressure sensor reaches the set threshold, the electric push rod 66 drives the air cylinder 63 forward, and the hot air is ejected outward from the air hole A42 of the air inlet sleeve 4;

[0130] S6: When the air temperature sensed by the third temperature sensor reaches the high temperature threshold, the electric push rod 66 drives the air cylinder 63 forward, and air is ejected outward from the air hole B52 of the air outlet sleeve 5. The operation time is maintained for a certain period of time. The operation time should be sufficient to allow the rock temperature of the target layer to rise to a temperature close to the set high temperature threshold. Therefore, it should be ≥ 8 hours. As a solution that takes both functionality and economy into consideration, the preferred operation time is 12 hours. During on-site operations, the operation time can also be appropriately extended or shortened based on comprehensive considerations such as the ambient temperature and ground temperature during the operation.

[0131] S7, repeat step S4 to complete the first round of hot and cold shock to the target layer;

[0132] S8, repeating steps S2 to S7 to complete the second round of hot and cold shock; and performing N rounds of hot and cold shock on the target layer in this order;

[0133] S9: Turn off the cooling and heating devices, open all valves in this embodiment, and open air holes A42 and B52 to weather the target layer for a specified period of time. The weathering operation time should be ≥ 10 hours. As a solution that balances functionality and economy, the preferred operation time is 15 hours.

[0134] In this embodiment,

[0135] Preferably, the system is further provided with a residual air water tank. The air outlet of the air outlet sleeve 5 is connected to the bottom of the residual air water tank via a hose. The air discharged from the air outlet of the air outlet sleeve 5 is heated or cooled in the residual air water tank before being discharged into the return air lane of the mine.

[0136] According to the above-mentioned roof water inrush control system, the present invention provides a roof water inrush control method based on physicochemical modification of overlying rock strata in coal mines, comprising the following steps.

[0137] S1, determine the area N of the advance treatment area based on the air diffusion radius R.

[0138] The diffusion coefficient D of air in the target layer of the mining operation area is calculated by the following formula (1):

[0139]

[0140] Where,

[0141] D—Diffusion coefficient under medium A and B conditions, m 2 / s;

[0142] α—correction coefficient;

[0143] v A —Flow rate of medium A, m / s;

[0144] T A —Pumping air temperature, K; T B —Air temperature of target layer, K;

[0145] M A 、M B —Molar mass of gases A and B, kg / kmol;

[0146] ρ A , ρ B —Density of gases A and B, kg / m 3 ;

[0147] P A —Pumping air pressure, Pa; P B —Gas pressure in the target layer, Pa.

[0148] The effective diffusion radius R of the air ejected from the air inlet sleeve is calculated using the following formula (2):

[0149]

[0150] Where,

[0151] R—effective air diffusion radius, m;

[0152] D—Diffusion coefficient under medium A and B conditions, m 2 / s;

[0153] T A —Pumping air temperature, K, T B —Target layer air temperature, K;

[0154] Φ—rock porosity;

[0155] t—time, s.

[0156] The strike length l of the working face in the mining area is calculated using the following formula (3):

[0157] l=2nR (3)

[0158] Where,

[0159] l—working face strike length, m;

[0160] n—number of sleeves, pieces.

[0161] The area N of the advanced treatment area is calculated by the following formula (4):

[0162] N=lb (4)

[0163] Where,

[0164] N—area of ​​advanced treatment range, m 2 ;

[0165] b—inclination length of working face, m;

[0166] l—working face strike length, m.

[0167] S2, in the advanced treatment area, the target layer area is reinforced using a hydraulic support 16, and multiple hydraulic fracturing boreholes are opened parallel to the target layer, and the rock blocks of the target layer are pre-treated by hydraulic fracturing.

[0168] S3, using directional drilling technology, within the scope of advanced treatment,

[0169] Along the middle of the section transport tunnel, multiple air intake channels are drilled vertically upward from the roof at a certain distance, and the depth of the air intake channels extends to a certain distance from the target layer;

[0170] Along the middle of the section return air channel, multiple air outlet channels are drilled vertically upward from the top plate at a certain distance, and the depth of the air outlet channels extends to a certain distance from the target layer;

[0171] The air inlet and outlet holes are set on both sides of the target layer and are separated by a certain distance. The distance should be set so that the air ejected from the air inlet can fully flow through the target layer and then be ejected from the air outlet hole.

[0172] S4, installing the air inlet sleeve 4 and the air outlet sleeve 5 into the air inlet channel and the air outlet channel respectively, and fixing them.

[0173] S5, according to the actual geological conditions of the target layer, the minimum pumping pressure P of the high-pressure air pump 1 is determined by the following formula (5): min ,

[0174]

[0175] Where,

[0176] P1—air pressure under standard atmospheric pressure, Pa; P2—air pressure in the actual working surface, Pa;

[0177] F—pumping air pressure, KN;

[0178] S—sleeve port area, m 2 ;

[0179] K—correction coefficient.

[0180] S6, using the first temperature sensor, adjusting the size of the refrigeration sleeve 11 of the refrigeration device so that the temperature of the air flowing out of the refrigeration pipe 2 is less than -50°C;

[0181] Using the second temperature sensor, adjust the number, position, and operating power of the heating device coils so that the temperature of the air flowing out of the heating pipe 3 is greater than 300°C;

[0182] According to the minimum pump outlet pressure P calculated in step S5 min , adjust the operating power of the high-pressure air pump 1 so that the pump pressure of the high-pressure air pump 1 P>P min .

[0183] S7, using the PLC control cabinet, performs hot and cold shock cycles and weathering treatment on the target layer through the following steps.

[0184] S7-1, close the third valve 14 and the fourth valve 15, drive the air cylinder 63 through the electric push rod 66 to close the air hole A42 and the air hole B52, and start the high-pressure air pump 1;

[0185] S7-2, open the first valve 7 and the second valve 8. When the pressure sensor reaches the set threshold, the electric push rod 66 drives the air cylinder 63 forward, and cold air is ejected outward from the air hole A42 of the air intake sleeve 4;

[0186] S7-3, when the air temperature sensed by the third temperature sensor reaches the low temperature threshold, the electric push rod 66 drives the air cylinder 63 forward, and air is ejected outward from the air hole B52 of the air outlet sleeve 5, and the operation is maintained for a certain period of time;

[0187] S7-4, close the first valve 7 and the second valve 8, and drive the air cylinder 63 to close the air hole A42 and the air hole B52 through the electric push rod 66;

[0188] S7-5, open the third valve 14 and the fourth valve 15. When the pressure sensor reaches the set threshold, the electric push rod 66 drives the air cylinder 63 forward, and hot air is ejected outward from the air hole A42 of the air inlet sleeve 4;

[0189] S7-6: When the air temperature sensed by the third temperature sensor reaches the high temperature threshold, the electric push rod 66 drives the air cylinder 63 forward, and air is ejected outward from the air hole B52 of the air outlet sleeve 5, and the operation is maintained for a certain period of time;

[0190] S7-7, repeat step S7-4 to complete the first round of hot and cold shock to the target layer;

[0191] S7-8, repeating steps S7-2 to S7-7 to complete the second round of hot and cold shocks; and performing N rounds of hot and cold shocks on the target layer in this order;

[0192] S7-9, turning off the cooling device and the heating device, opening all valves in this embodiment, and opening the air hole A42 and the air hole B52, and performing weathering treatment on the target layer for a certain period of time.

[0193] S8, the air outlet of the air outlet sleeve 5 is connected to the bottom of the residual air water tank through a hose, and the air discharged from the air outlet of the air outlet sleeve 5 is heated or cooled in the residual air water tank and then discharged into the return air lane of the mine.

[0194] In the above steps,

[0195] Preferably, the spacing distances between the air inlet holes and the air outlet holes should be set based on the diffusion radius R of the air under low temperature conditions.

[0196] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A roof water inrush control system based on physical and chemical modification of overlying rock strata in coal mines, characterized by: Including high-pressure air pump, refrigeration pipe, refrigeration device, heating pipe, heating device, air inlet sleeve and air outlet sleeve, in, The high-pressure air pump is installed in the coal mine tunnel for pumping air, and the air outlet pipe of the high-pressure air pump is connected to the cooling pipe and the heating pipe respectively through a tee pipe; The two ends of the refrigeration pipeline are respectively connected to the high-pressure air pump and the air intake sleeve, and the two ends of the refrigeration pipeline are respectively provided with a first valve and a second valve; The refrigeration device is used to cool the air in the refrigeration pipe; The two ends of the heating pipe are respectively connected to the high-pressure air pump and the air intake sleeve, and the two ends of the heating pipe are respectively provided with a third valve and a fourth valve; The heating device is used to heat the air in the heating pipe; The air inlet sleeve and the air outlet sleeve are hollow cylindrical structures with sealed ends, and air holes are opened on the walls of the cylinders; an air inlet is opened on one end surface of the air inlet sleeve, and an air outlet is opened on one end surface of the air outlet sleeve; the air inlet sleeve is located in the transport lane, and the air outlet sleeve is located in the return air lane. The air inlet sleeve and the air outlet sleeve are installed on both sides of the target layer of the coal mining area respectively; The air pumped out by the high-pressure air pump can pass through the cooling pipe and / or the heating pipe, and then be ejected from the air outlet sleeve after passing through the target layer from the air inlet sleeve; A gas control device is provided inside the air inlet sleeve and the air outlet sleeve, and the gas control device can control the opening and closing of the air holes of the air inlet sleeve and the air outlet sleeve; The gas control device includes a limit plate, a spring, a gas cylinder and an electric push rod. The limiting plate is provided with a gas passage and is installed below the gas cylinder. The spring is installed on the limiting plate and connected to the gas cylinder. The top of the air cylinder is sealed, the bottom is provided with a second air inlet, and the surrounding areas are provided with adjustment holes corresponding to the air holes; The electric push rod is arranged on the inner top surface of the air inlet sleeve and / or the air outlet sleeve, and its front end is fixedly connected to the air cylinder; when the air cylinder is extended or retracted to a certain stroke under the pulling of the electric push rod, the air hole can be closed or opened.

2. The roof water inrush control system based on physicochemical modification of overlying strata in coal mines according to claim 1 is characterized in that: The system is also provided with a control system, which includes a computer, a PLC control cabinet, a first temperature sensor, a second temperature sensor, a third temperature sensor and a pressure sensor. in, The first temperature sensor is installed on the refrigeration pipe, the second temperature sensor is installed on the heating pipe, the third temperature sensor is installed at the air outlet sleeve, and the pressure sensor is arranged at the air inlet sleeve; The two ends of the refrigeration pipe are respectively provided with a first valve and a second valve, and the two ends of the heating pipe are respectively provided with a third valve and a fourth valve; The refrigeration pipe is provided with a first temperature sensor near the air inlet sleeve, the heating pipe is provided with a second temperature sensor near the air inlet sleeve, the air outlet sleeve is provided with a third temperature sensor, and the air inlet sleeve is provided with a pressure sensor; The high-pressure air pump, the first valve, the second valve, the third valve, the fourth valve, the first temperature sensor, the second temperature sensor, the third temperature sensor, the pressure sensor and the electric push rod are connected to the PLC control cabinet through a signal transmission line, and are used to transmit information to the PLC control cabinet and execute the operating instructions of the PLC control cabinet; the PLC control cabinet is connected to the computer through a signal transmission line, and is used to receive and transmit the operating instructions of the computer.

3. The roof water inrush control system based on physicochemical modification of overlying strata in coal mines according to claim 1 is characterized in that: The refrigeration device includes a liquid nitrogen storage tank, a liquid nitrogen pump, a refrigeration sleeve and a liquid nitrogen recovery tank. in, The refrigeration sleeve is an annular tube, and the refrigeration pipeline passes through the refrigeration sleeve along the axis; A liquid inlet and a liquid outlet are respectively provided at both ends of the refrigeration sleeve, and the liquid inlet is connected to the liquid nitrogen storage tank through the liquid nitrogen pump; The liquid outlet is connected to the liquid nitrogen recovery tank through a hose; after the liquid nitrogen pump is started, the liquid nitrogen is pumped out from the liquid nitrogen storage tank, and the liquid nitrogen fills the refrigeration sleeve and flows from the liquid outlet to the liquid nitrogen recovery tank.

4. The roof water inrush control system based on physicochemical modification of overlying strata in coal mines according to claim 1 is characterized in that: The heating device is an electromagnetic induction heater, which is provided with multiple sets of induction coils and can locally heat the heating pipe step by step.

5. The roof water inrush control system based on physicochemical modification of overlying strata in coal mines according to claim 1 is characterized in that: The cooling pipe and the heating pipe are made of cast iron and are provided with a heat insulation wrapping layer.

6. The roof water inrush control system based on physicochemical modification of overlying strata in coal mines according to claim 1 is characterized in that: The system is also provided with a residual air water tank, and the air outlet of the air outlet sleeve is connected to the bottom of the residual air water tank through a hose.

7. A method for controlling roof water inrush based on physical and chemical modification of overlying strata in coal mines, comprising the following steps: S1, according to the air diffusion radius R, determine the area N of the advanced treatment area, The diffusion coefficient D of air in the target layer of the mining operation area is calculated by the following formula (1): （1） Where, —In the medium 、 The diffusion coefficient under the conditions , —Correction coefficient, —Flow rate of medium A, , — pumped air temperature, , — target layer air temperature, , 、 -gas 、 The molar mass of , 、 -gas 、 The density, , —Pumping air pressure, , —Gas pressure in the target layer, ; The effective diffusion radius R of the air ejected from the air inlet sleeve is calculated using the following formula (2): （2） Where, —Effective air diffusion radius, , —In the medium 、 The diffusion coefficient under the conditions , — pumped air temperature, , — target layer air temperature, , — rock formation porosity, t—time, s; The strike length of the working face in the mining area is calculated using the following formula (3): , （3） Where, — Working face strike length, , —Number of sleeves, pcs; The area N of the advanced treatment area is calculated by the following formula (4): （4） Where, —Area of ​​advanced treatment scope, , — working face inclination length, , — Working face strike length, ; S2: In the advanced treatment area, multiple hydraulic fracturing boreholes are opened parallel to the target layer, and the rock blocks of the target layer are pre-treated by hydraulic fracturing; S3, within the scope of advanced governance, In the middle of the section transport tunnel, multiple air intake holes are drilled vertically upward from the top plate at a certain distance. The depth of the air intake holes extends to a certain distance from the target layer. Along the middle of the section return air channel, multiple air outlet channels are drilled vertically upward from the top plate at a certain distance. The depth of the air outlet channels extends to a certain distance from the target layer. The air inlet and outlet holes are set on both sides of the target layer and are separated by a certain distance; S4, installing the air inlet sleeve and the air outlet sleeve into the air inlet channel and the air outlet channel respectively, and fixing them; S5, according to the actual geological conditions of the target layer, the minimum pumping pressure P of the high-pressure air pump is determined by the following formula (5): min , （5） Where, —Air pressure at standard atmospheric pressure, ; —Air pressure when in the actual working surface, , —Pumping air pressure, , — sleeve port area, , —correction factor; S6, using the first temperature sensor, adjust the size of the refrigeration sleeve of the refrigeration device so that the temperature of the air flowing out of the refrigeration pipe is less than -50°C. Use the second temperature sensor to adjust the number, position and operating power of the heating device coils so that the temperature of the air flowing out of the heating pipe is greater than 300°C. According to the minimum pump outlet pressure P calculated in step S5 min , adjust the operating power of the high-pressure air pump so that the pump pressure of the high-pressure air pump P>P min ; S7, using a PLC control cabinet, performs thermal shock cycles and weathering treatment on the target layer through the following steps: S7-1, close the third valve and the fourth valve, close the air holes of the air inlet sleeve and the air outlet sleeve, and start the high-pressure air pump; S7-2, opening the first valve and the second valve. When the pressure sensor reaches a set threshold, the air holes of the air intake sleeve are opened, and cold air is ejected outward from the air holes of the air intake sleeve. S7-3, when the air temperature sensed by the third temperature sensor reaches a low temperature threshold, the air holes of the air outlet sleeve are opened, and air is ejected outward from the air holes of the air outlet sleeve, and the operation is maintained for a certain period of time; S7-4, closing the first valve and the second valve to close the air holes of the air inlet sleeve and the air outlet sleeve; S7-5, opening the third valve and the fourth valve. When the pressure sensor reaches the set threshold, the air holes of the air intake sleeve are opened, and hot air is ejected outward from the air holes of the air intake sleeve. S7-6, when the air temperature sensed by the third temperature sensor reaches a high temperature threshold, the air holes of the air outlet sleeve are opened, and air is ejected outward from the air holes of the air outlet sleeve, and the operation is maintained for a certain period of time; S7-7, repeat step S7-4 to complete the first round of hot and cold shock to the target layer; S7-8, repeating steps S7-2 to S7-7 to complete the second round of hot and cold shocks; and performing N rounds of hot and cold shocks on the target layer in this order; S7-9, turning off the cooling device and the heating device, opening all valves, and opening the air holes of the air inlet sleeve and the air outlet sleeve, and performing weathering treatment on the target layer for a certain period of time; S8, the air outlet of the air outlet sleeve is connected to the bottom of the residual air water tank through a hose. The air discharged from the air outlet of the air outlet sleeve is heated or cooled in the residual air water tank and then discharged into the return air lane of the mine.

8. The method for treating roof water inrush based on physicochemical modification of overlying strata in coal mines according to claim 7, characterized in that: The spacing distances between the air inlet holes and the air outlet holes should be set based on the diffusion radius R of the air under low temperature conditions.

Images