Experimental system and method for simulating power plant flue gas long-distance conveying fly ash to fill coal mine goaf

Abstract

The invention discloses an experimental system and method for filling coal mine goaf by remotely conveying coal ash through power plant smoke, and belongs to the technical field of coal mine goaf filling. The experimental system comprises an air source system, a material conveying system, an air supply system and a goaf receiving system, the gas source system comprises a nitrogen gas cylinder, a carbon dioxide gas cylinder, a gas proportioning device, a gas storage tank, a freezing dryer and a gas conveying pipeline; the material conveying system comprises a hopper, a sending bin pump, a control valve and a material conveying pipeline; the gas conveying pipeline is communicated with the material conveying pipeline; the air supply system comprises an air supply pipeline, and the air supply pipeline and the material conveying pipeline are both connected with a Y-shaped vertical conveying pipeline; and the Y-shaped vertical conveying pipeline is connected with a goaf receiving system. A new implementation scheme is provided for long-distance coal ash conveying for coal mine goaf filling, efficient inerting fire preventing and extinguishing and crack filling of the goaf can be achieved, and meanwhile a parameter optimization basis is provided for actual engineering.

Description

Technical Field

[0001] The present invention belongs to the technical field of gob filling in coal mines, and particularly relates to an experimental system and method for simulating the long-distance transportation of fly ash from power plant flue gas to fill the gob in coal mines. Background Art

[0002] Existing gob filling technologies include grouting filling, paste filling, etc., which have problems such as short transportation distance, low filling rate, high cost, and complex process. At present, coal-fired power plants generate a large amount of flue gas and fly ash waste every year. Among them, the main components of the flue gas, carbon dioxide and nitrogen, are excellent inert gases for fire prevention. Transporting the power plant flue gas and fly ash to the underground gob can not only inertize the gob to prevent spontaneous combustion of the remaining coal, but also fill the rock fissures to reduce surface subsidence. However, there are many problems with traditional transportation methods:

[0003] (1) Existing transportation methods are difficult to balance pipeline wear and filling effect, resulting in increased transportation costs and difficult to guarantee the filling quality of the gob. For example, dilute-phase transportation has large wear and high energy consumption, and dense-phase transportation has poor filling effect, both of which increase the overall transportation cost and the gob cannot be well filled.

[0004] (2) The mixing of fly ash and flue gas is uneven, which is prone to local blockage and reduces the stability and reliability of the transportation system.

[0005] (3) The monitoring means for the filling degree of the gob are backward, lacking a simulation device for the complex structure of the gob, with poor adaptability in practical applications, unable to accurately reflect the overall filling state of the gob, affecting the stability of the gob and increasing the risk of surface collapse. Summary of the Invention

[0006] In view of the above technical problems, the present invention proposes an experimental system and method for simulating the long-distance transportation of fly ash from power plant flue gas to fill the gob in coal mines, providing a basis for optimizing on-site implementation.

[0007] The technical solution adopted by the present invention is:

[0008] An experimental system for the long-distance transportation of fly ash from power plant flue gas to fill the gob in coal mines includes a gas source system, a material transportation system, a gas supplementing system, and a gob receiving system;

[0009] The gas source system includes nitrogen gas cylinders, carbon dioxide gas cylinders, a gas proportioning device, a gas storage tank, a cold dryer, and a gas transportation pipeline. The nitrogen gas cylinders and carbon dioxide gas cylinders are connected to the gas proportioning device, the gas proportioning device is connected to the gas storage tank, the gas storage tank is connected to the cold dryer, and the cold dryer is connected to the gas transportation pipeline;

[0010] The material conveying system includes a hopper, a sending silo pump, a control valve, and a material conveying pipeline. The discharge port of the hopper is connected to the control valve through the sending silo pump, and the control valve is connected to the material conveying pipeline; the gas conveying pipeline is connected to the material conveying pipeline.

[0011] The air supplement system includes an air supplement pipeline. Both the air supplement pipeline and the material conveying pipeline are connected to a Y-shaped vertical conveying pipeline; the Y-shaped vertical conveying pipeline is connected to a goaf receiving system.

[0012] The goaf receiving system includes a goaf simulation device filled with crushed rock simulation particles. The bottom end of the Y-shaped vertical conveying pipeline extends deep into the goaf simulation device; a dust processor is provided at the top of the goaf simulation device.

[0013] The present invention also provides an experimental method for simulating the long-distance transportation of fly ash from a power plant flue gas to fill a coal mine goaf. Using the experimental system as described above, it includes the following steps:

[0014] (1) Transport the nitrogen in the nitrogen gas cylinder and the carbon dioxide in the carbon dioxide gas cylinder to the gas proportioning device, and ensure that the composition of the obtained mixed gas is basically the same as that of the flue gas through the gas proportioning device; the mixed gas proportioned in the gas proportioning device is stored in the gas storage tank.

[0015] (2) The mixed gas in the gas storage tank is cooled and dried by a cold dryer, and then transported through the gas conveying pipeline; a first flow regulating device is provided on the gas conveying pipeline. The flowmeter in the first flow regulating device is used to monitor the gas flow rate change in the gas conveying pipeline in real time, and the pressure transmitter in the first flow regulating device is used to adjust the pressure in the gas conveying pipeline; the gas conveying pipeline is respectively connected to the material conveying pipeline and the air supplement pipeline.

[0016] (3) The fly ash stored in the hopper enters the sending silo pump. The sending silo pump closes the feed port and starts to inflate and pressurize, and then opens the discharge port to discharge through the lower control valve, and is sent into the material conveying pipeline and transported along with the mixed gas in the material conveying pipeline; the second flow regulating device is adjusted to control the flow rate of the mixed gas, and the control valve is adjusted to perform fly ash transportation with a high solid-gas ratio in the material conveying pipeline.

[0017] (4) Part of the mixed gas in the gas conveying pipeline is also transported through the air supplement pipeline. The pressure transmitter in the third flow regulating device is used to adjust the pressure in the air supplement pipeline and increase the flow rate of the mixed gas in the air supplement pipeline.

[0018] (5) The fly ash in the material conveying pipeline and the mixed gas in the air supplement pipeline are mixed through the Y-shaped vertical conveying pipeline in the goaf receiving system and then conveyed to the simulated roadway in the goaf simulation device. They diffuse into the goaf through the simulated roadway, inerting and filling the goaf area. After the fly ash smoke flow fully flows in the goaf, it is discharged after being purified by the dust processor at the top.

[0019] The beneficial technical effects of the present invention are as follows:

[0020] (1) The present invention uses simulated flue gas as the conveying gas source, and the fly ash is transported to the surface of the coal mine by dense-phase pneumatic conveying. At the surface of the coal mine, secondary air supplementation is used to blow the fly ash in the pipeline into a dilute-phase suspension flow state. Finally, the flue gas and fly ash are transported to the underground goaf through the vertical boreholes in the coal seam. An experimental simulation is carried out on this scheme, and the feasibility is determined according to the filling effect, and the fly ash conveying volume, the simulated flue gas flow rate in the air supplement system, etc. are optimized.

[0021] (2) The present invention combines the advantages of dense-phase and dilute-phase conveying. In the material conveying system, a lower gas flow rate is adopted to achieve the transportation of fly ash with a high solid-gas ratio, reducing energy consumption and wear. In the air supplement system, a higher gas flow rate is adopted to achieve the dilute-phase transportation of fly ash with a low solid-gas ratio in the pipeline of the goaf receiving system, improving the diffusion and filling effect of fly ash. The present invention provides a new implementation scheme for the long-distance transportation of fly ash for the filling of coal mine goafs.

[0022] (3) The present invention arranges the Y-shaped vertical conveying pipeline in the center of the goaf simulation device, and the bottom of the Y-shaped vertical conveying pipeline is inserted into the middle position of the simulated roadway, thus simulating the use of the remaining roadway in the goaf as the main channel for the diffusion of flue gas and fly ash. From the experimental results, this method greatly improves the diffusion distance and filling effect of flue gas and fly ash.

[0023] (4) The present invention arranges the goaf simulation device in layers and uses three-dimensional laser scanning to monitor the filling effect of the goaf after the experiment, which can accurately and quantitatively evaluate the filling effect. Moreover, the present invention further constructs a mathematical model, etc. In practical engineering applications, when new solid-gas ratio and goaf rock particle size data are obtained, they are input into the constructed model, and the corresponding predicted values of the filling degree and filling range can be output, providing data support for on-site implementation, helping engineers predict the filling effect in advance, and optimizing the conveying parameters and goaf treatment plan. Brief Description of the Drawings

[0024] Figure 1 It is a schematic structural diagram of the experimental system for simulating the long-distance transportation of fly ash from a power plant flue gas to fill a coal mine goaf of the present invention;

[0025] Figure 2 It is a schematic structural diagram of the gas source system part in the experimental system of the present invention;

[0026] Figure 3 It is a schematic structural diagram of the material conveying system part in the experimental system of the present invention;

[0027] Figure 4 It is a three-dimensional structural diagram of the goaf receiving system part in the experimental system of the present invention;

[0028] Figure 5 It is a schematic flow diagram of the experimental method for simulating the long-distance transportation of fly ash from power plant flue gas to fill the goaf of coal mines in the present invention.

[0029] In the figure: 1 - gas source system, 2 - material conveying system, 3 - air supplement system, 4 - goaf receiving system, 5 - Y-shaped vertical conveying pipe, 6 - three-dimensional laser scanner, 7 - dust processor, 8 - first flow regulating device, 9 - second flow regulating device, 10 - mixing chamber, 11 - third flow regulating device;

[0030] 101 - nitrogen gas cylinder, 102 - carbon dioxide gas cylinder, 103 - gas proportioning device, 104 - gas storage tank, 105 - cold dryer, 106 - gas conveying pipe; 201 - hopper, 202 - sending bin pump, 203 - control valve, 204 - material conveying pipe; 301 - air supplement pipe; 401 - topmost cuboid, 402 - middle cuboid, 403 - bottommost cuboid, 404 - simulated roadway, 405 - second ventilation hole, 406 - sealing plate, 407 - jack, 408 - observation port, 409 - handle; 801 - flowmeter, 802 - pressure transmitter, 803 - regulating valve. Detailed implementation manners

[0031] The present invention provides a simulation experiment system and method for using power plant flue gas (mainly composed of carbon dioxide and nitrogen) as a gas source medium to long-distance transport fly ash to the surface of the goaf of a coal mine, equipped with a flue gas air supplement system established on the surface to blow the fly ash in the pipeline into a suspended flow state and transport it to the goaf through a drilling casing communicating with the goaf. The present invention provides a new implementation scheme for long-distance transporting fly ash to fill the goaf of a coal mine, and combines intelligent control and three-dimensional scanning technology to achieve efficient inerting fire prevention and crack filling in the goaf, and at the same time provides a basis for parameter optimization for actual projects.

[0032] The following further describes the present invention in conjunction with the accompanying drawings and specific implementation manners.

[0033] As Figure 1 shown, an experimental system for long-distance transporting fly ash from power plant flue gas to fill the goaf of a coal mine includes a gas source system 1, a material conveying system 2, an air supplement system 3, and a goaf receiving system 4. As Figure 2As shown in the figure, the gas source system 1 includes a nitrogen gas cylinder 101, a carbon dioxide gas cylinder 102, a gas proportioning device 103, a gas storage tank 104, a cold dryer 105, and a gas transmission pipeline 106. The nitrogen gas cylinder 101 and the carbon dioxide gas cylinder 102 are connected to the gas proportioning device 103. The gas proportioning device is set according to the nitrogen and carbon dioxide ratios of the power plant flue gas to ensure that the gas components flowing out of the gas proportioning device are basically the same as those of the flue gas. The gas proportioning device 103 is connected to the gas storage tank 104, and the gas storage tank 104 is connected to the cold dryer 105. The proportioned flue gas component gas is stored in the gas storage tank to provide a stable gas source for fly ash transportation. The cold dryer 105 is connected to the gas transmission pipeline 106, and the cold dryer 105 cools and dries the flue gas to prevent fly ash from adhering to the pipe wall.

[0034] As Figure 3 shown in the figure, the material transportation system 2 includes a hopper 201, a sending silo pump 202, a control valve 203, and a material transportation pipeline 204. The discharge port of the hopper 201 is connected to the control valve 203 through the sending silo pump 202, and the control valve 203 is connected to the material transportation pipeline 204. The gas transmission pipeline 106 is connected to the material transportation pipeline 204. The fly ash stored in the hopper 201 falls into the sending silo pump 202, and the sending silo pump 202 is inflated and pressurized to pump the fly ash in the silo pump to the control valve 203 such as a rotary air lock valve, and the rotary air lock valve is connected to the material transportation pipeline 204.

[0035] The air supplement system 3 includes an air supplement pipeline 301. The air supplement pipeline 301 and the material transportation pipeline 204 are both connected to the Y-shaped vertical transportation pipeline 5. The Y-shaped vertical transportation pipeline 5 is connected to the goaf receiving system 4. The goaf receiving system 4 includes a goaf simulation device filled with crushed rock simulation particles, and the bottom end of the Y-shaped vertical transportation pipeline 5 extends into the goaf simulation device. A dust processor 7 is provided at the top of the goaf simulation device.

[0036] Specifically, as Figure 4 shown in the figure, the goaf simulation device is arranged in layers and is stacked one above the other by cuboids with open tops. Specifically, it includes the uppermost cuboid 401, several middle cuboids 402, and the lowermost cuboid 403. Each cuboid is filled with crushed rock simulation particles. A simulated roadway 404 is arranged at the center of the lowermost cuboid 403 along its length direction, and several first ventilation holes are arranged on both sides of the simulated roadway 404. Several second ventilation holes 405 are provided at the bottoms of the uppermost cuboid 401 and several middle cuboids 402, and a sealing plate 406 is provided at the top of the uppermost cuboid 401. The sealing plate 406 is also made of stainless steel and is connected to the uppermost cuboid by bolts. The dust processor 7 is installed on the sealing plate 406.

[0037] Each of the above cuboids is welded by stainless steel plates, and the length, width and height of the cuboid can be obtained by proportional conversion according to the actual goaf range.

[0038] The above Y-shaped vertical conveying pipe 5 is located in the center of the goaf simulation device, and the bottom of the Y-shaped vertical conveying pipe 5 is inserted into the middle position of the simulated roadway 404. Jacks 407 convenient for inserting the Y-shaped vertical conveying pipe 5 are arranged at the corresponding positions on the sealing plate, the bottom of the topmost cuboid, the bottoms of several middle-layer cuboids, and the top of the simulated roadway.

[0039] Observation ports 408 are arranged around the bottommost cuboid 403, and on both sides of the simulated roadway corresponding to several middle-layer cuboids 402 and the topmost cuboid 401. The observation ports are sealed with acrylic plates. Handles 409 are arranged on the other two sides of several middle-layer cuboids 402 and the topmost cuboid 401 to facilitate moving each layer of cuboids. Before the experiment, the cuboids are stacked vertically one above the other, and broken rock simulation particles are filled in the cuboids. After the experiment is completed, first remove the sealing plate on the top of the topmost cuboid 401, and then scan with a three-dimensional laser scanner 6; after the scanning is completed, move the topmost cuboid 401 away, and then scan the top middle-layer cuboid with the three-dimensional laser scanner 6; in this way, until the scanning records of each layer of cuboids are completed.

[0040] As a further design of the present invention, a first flow regulating device 8 and a second flow regulating device 9 are arranged on the gas conveying pipe 106, and the inlet end of the gas conveying pipe 106 is connected to the cold dryer 105. One end of the material conveying pipe 204 is connected to the control valve 203, and a mixing chamber 10 is also arranged at this end. The outlet end of the gas conveying pipe 106 is connected to the material conveying pipe 204 through the mixing chamber 10, and the other end of the material conveying pipe 204 is connected to the Y-shaped vertical conveying pipe 5.

[0041] Furthermore, the inlet end of the air supplement pipe 301 is connected to the gas conveying pipe 106, and the connection point between the air supplement pipe and the gas conveying pipe is between the first flow regulating device 8 and the second flow regulating device 9. A third flow regulating device 11 is also arranged on the air supplement pipe 301. The first flow regulating device 8, the second flow regulating device 9 and the third flow regulating device 11 all include a flow meter 801, a pressure transmitter 802 and a regulating valve 803. The pressure transmitter 802 and the regulating valve 803 can monitor and adjust the gas conveying pressure in real time, and the flow meter 801 can monitor the gas flow rate change in real time. The gas conveying pipe 106 and the air supplement pipe 301 are both stainless steel pipes.

[0042] Further, the experimental system further includes a three-dimensional laser scanner 6, which is arranged directly above the goaf simulation device and is used to scan and record the fly ash filling conditions of each layer of cuboids. The first flow regulating device 8, the second flow regulating device 9, the third flow regulating device 11, the control valve 203 and the three-dimensional laser scanner 6 are all connected to the PLC control device.

[0043] The present invention combines the advantages of dense-phase and dilute-phase transportation, and realizes the transportation of fly ash with a high solid-gas ratio at a lower gas flow rate in the material transportation system, reducing energy consumption and wear; in the air supplement system, a higher gas flow rate is adopted to realize the dilute-phase transportation of fly ash with a low solid-gas ratio in the pipeline of the goaf receiving system, improving the diffusion and filling effect of fly ash. And by using the remaining roadway in the goaf as the main channel for the diffusion of flue gas and fly ash, the filling effect is greatly improved. Usually, a protective coal pillar is left on the side of the remaining roadway in the goaf. After the overlying strata of the working face collapse, a triangular area will be formed at the roadway position. The strata and coal pillar in the triangular area bear the main weight of the strata, making the roadway structure relatively intact, and also providing basic conditions for the long-distance migration and filling of flue gas and fly ash.

[0044] As Figure 5 shown, the present invention also provides an experimental method for simulating the long-distance transportation of fly ash from a power plant flue gas to fill a coal mine goaf. Using the experimental system described above, it includes the following steps:

[0045] (1) The high-purity nitrogen (99.9%) in the nitrogen gas cylinder 101 and the high-purity carbon dioxide (99.9%) in the carbon dioxide gas cylinder 102 are transported to the gas proportioning device 103. The nitrogen and carbon dioxide concentration ratios of the gas proportioning device are set to the nitrogen and carbon dioxide concentration ratios of the actual power plant flue gas, and the gas proportioning device 103 ensures that the obtained mixed gas composition is basically the same as the flue gas composition. The mixed gas proportioned in the gas proportioning device 103 is stored in the gas storage tank 104 to provide a stable gas source for fly ash transportation, and the pressure of the gas storage tank is adjusted according to the experimental situation.

[0046] (2) The mixed gas in the gas storage tank is cooled and dried by the cold dryer 105 to prevent high-temperature gas from damaging monitoring components such as pipelines and flow meters, reduce the gas humidity, and prevent fly ash from adhering to the pipe wall and causing pipeline blockage. Then it is transported through the gas transportation pipeline 106. A first flow regulating device 8 is arranged on the gas transportation pipeline 106. The flow meter in the first flow regulating device 8 is used to monitor the gas flow rate change in the gas transportation pipeline in real time, and the pressure transmitter in the first flow regulating device is used to adjust the pressure in the gas transportation pipeline. The gas transportation pipeline 106 is respectively connected to the material transportation pipeline 204 and the air supplement pipeline 301.

[0047] (3) The fly ash stored in the hopper 201 enters the sending silo pump 202. The sending silo pump 202 closes the feed inlet and starts to inflate and pressurize. Subsequently, the discharge outlet is opened to discharge through the lower control valve and is sent into the material conveying pipeline 204, and is conveyed along with the mixed gas in the material conveying pipeline 204. The flow rate of the mixed gas is controlled by adjusting the second flow regulating device 9, and the fly ash is conveyed in the material conveying pipeline with a high solid-gas ratio by adjusting the control valve.

[0048] (4) Part of the mixed gas in the gas conveying pipeline is also conveyed through the air supplement pipeline 301. The pressure in the air supplement pipeline is adjusted by the pressure transmitter in the third flow regulating device 11 to increase the flow rate of the mixed gas in the air supplement pipeline. For example, by adjusting the second flow regulating device 9, the gas flow rate of the material system is made lower, which is beneficial to the conveying of fly ash with a high solid-gas ratio (the ratio of the solid mass flow rate to the gas mass flow rate), achieving the purposes of small conveying energy consumption, long conveying distance, and small pipeline wear. By adjusting the third flow regulating device 11, the gas flow rate of the air supplement system is increased, which is beneficial to the dilute-phase conveying of fly ash with a low solid-gas ratio in the pipeline of the goaf receiving system. The flow rate of the flue gas containing fly ash increases and the migration distance is lengthened, achieving the effect of fully filling the goaf with fly ash.

[0049] (5) The fly ash in the material conveying pipeline and the mixed gas in the air supplement pipeline are mixed through the Y-shaped vertical conveying pipeline 5 in the goaf receiving system and are conveyed to the simulated roadway 404 in the goaf simulation device. While migrating in the simulated roadway, it diffuses into the goaf through the first air vents on both sides of the simulated roadway 404 to inert and fill the goaf area. After the fly ash flue gas fully flows in the goaf, it is discharged after being purified by the dust processor 7 at the top.

[0050] (6) The flow and diffusion conditions of the fly ash flue gas in the goaf are observed through the observation port 408, and it is also possible to judge when to stop the experiment.

[0051] (7) After the experiment is completed, the goaf simulation device is disassembled, and it is observed from top to bottom and scanned by the 3D laser scanner 6 in sequence; the fly ash conveying amount in the material conveying pipeline 204 and the mixed gas flow rate in the air supplement pipeline 301 are continuously optimized through the experiment.

[0052] The present invention can continuously adjust the flue gas flow rate and the fly ash pumping amount of the material conveying system through experiments, providing an important reference for the optimal solid-gas ratio of the material conveying system. The present invention can also continuously adjust the flue gas flow rate of the air supplement system and the fly ash conveying amount of the material conveying system through experiments, enabling the fly ash to enter the goaf receiving system in a suspended flow state, providing an important reference for the equipment selection of the material conveying system and the air supplement system.

[0053] Further, the experimental method further includes the following steps:

[0054] (8) The PLC control device is used to collect the mass flow rate M of fly ash in the material conveying system and the mixed gas flow rate Q of the air supplement system in real time, so that the solid-gas ratio S = M / Q is always maintained within a preset threshold range.

[0055] (9) Continuously adjust the combination of the solid-gas ratio and the particle size of the crushed rock simulation particles filled in the goaf simulation device, and conduct goaf filling experiments. Each group of experiments is repeated multiple times.

[0056] (10) After the experiment is completed, disassemble the goaf simulation device and conduct two-dimensional laser scanning layer by layer. Import the scanning data into the modeling software to generate a three-dimensional point cloud model. Divide the grid units and calculate the filling degree of each grid unit.

[0057] (11) Statistically analyze the filling degree C and the filling range R. The filling degree C = filling volume / goaf void volume, and the filling range R = maximum diffusion distance.

[0058] (12) Establish a quantitative relationship model among the solid-gas ratio S, the particle size D of the crushed rock simulation particles, the filling degree C, and the filling range R:

[0059] C = k1·(S / D) n +b

[0060] R = k2·lnS + m·D

[0061] Wherein, k1, k2, n, b, and m are experimental fitting coefficients.

[0062] Adopt multiple regression analysis to fit the parameter relationship and obtain the experimental fitting coefficients.

[0063] (13) In actual engineering applications, when new solid-gas ratio and goaf rock particle size data are obtained, input them into the trained model to obtain the corresponding predicted values of the filling degree and the filling range, providing data support for on-site implementation.

[0064] The present invention provides an experimental system and method that combines the advantages of low wear in dense-phase transportation and high diffusion speed in dilute-phase transportation, which is conducive to realizing the long-distance transportation of fly ash from power plant flue gas to fill coal mine goafs and solving the drawbacks of traditional transportation methods. The experimental system of the present invention combines three-dimensional laser scanning technology to quantify the goaf filling effect. The present invention also establishes a mathematical model of the solid-gas ratio, the particle size of the goaf crushed particles, and the filling parameters, providing an optimization basis for on-site implementation. And the transportation parameters can be dynamically adjusted through intelligent control to ensure the efficient and stable operation of the system.

[0065] The following further illustrates the method of the present invention in combination with specific application examples.

[0066] Step 1: Gas source configuration;

[0067] Mix nitrogen and carbon dioxide in the proportion of power plant flue gas (e.g., CO2: 15%, N2: 85%), and after stabilizing the pressure through a gas storage tank, cool it to below 25°C through a cold dryer.

[0068] Step 2: PLC data monitoring and adjustment;

[0069] Collect the mass flow rate M of fly ash in the material conveying system and the flue gas flow rate Q of the air supplement system in real time, so that the solid-gas ratio S = M / Q is always maintained within the preset threshold range.

[0070] Continuously adjust the combination of the solid-gas ratio gradient (S = 20, 35, 50) and the rock particle size (D = 5mm, 10mm, 15mm), a total of 9 groups of experiments; each group of experiments is repeated 3 times to ensure the reliability of the data.

[0071] Step 3: Goaf filling;

[0072] After the fly ash enters the simulated roadway through the pipeline, it diffuses into the goaf through the ventilation holes for filling. After the air flow passes through the entire goaf area, it is discharged after being purified by the dust processor (filtration efficiency ≥ 99%) at the top.

[0073] Step 4: 3D scanning and data acquisition;

[0074] (1) After the experiment, disassemble the goaf simulation device and perform two-dimensional laser scanning (resolution 0.1mm) layer by layer.

[0075] (2) Import the scanned data into modeling software (such as MATLAB) to generate a 3D point cloud model.

[0076] (3) Divide the grid cells (10cm × 10cm × 10cm) and calculate the filling density (ρ i = m i / v i ) of each cell.

[0077] Step 5: Mathematical model construction;

[0078] (1) Statistically analyze the filling degree (C = filling volume / goaf void volume) and the filling range (R = maximum diffusion distance);

[0079] (2) Use multiple regression analysis to fit the parameter relationship and obtain the model coefficients (for example: k1 = 0.85, n = 0.6, b = 0.1).

[0080] Step 6: Model verification;

[0081] (1) Input the parameters of the target goaf (rock particle size D, porosity), and calculate the optimal solid-gas ratio S through the model;

[0082] (2) The PLC control device dynamically adjusts the air supplement volume and the fly ash conveying volume according to the optimal solid-gas ratio S;

[0083] (3) After the experiment is completed, three-dimensional scanning is carried out to verify the goaf filling effect. Compare the goaf filling degree C and the filling range R with the predicted values, and an error ≤ 5% is regarded as effective.

[0084] Step 7: On-site engineering application;

[0085] In actual engineering applications, when new solid-gas ratio and goaf rock particle size data are obtained, they are input into the trained model, and the model can output the corresponding predicted values of the filling degree and the filling range, providing data support for on-site implementation, helping engineers estimate the filling effect in advance, and optimizing the conveying parameters and the goaf treatment plan.

[0086] In summary, the present invention adopts the advantages of both dense-phase and dilute-phase transportation to solve the problem of long-distance transportation of fly ash from power plant flue gas to fill coal mine goafs, reducing the transportation cost and improving the filling quality. It truly simulates the actual goaf scenario, proposes to use the remaining roadways in the goaf as the main transportation channels for the diffusion of flue gas and fly ash, greatly improving the diffusion distance of flue gas and fly ash and the filling effect. Using three-dimensional laser scanning to monitor the goaf filling effect can accurately and quantitatively evaluate the filling effect, providing reliable data support for actual projects.

[0087] The parts not described in the above manner can be achieved by adopting or referring to existing technologies.

[0088] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. An experimental system for transporting fly ash from power plant flue gas over a long distance to fill the gob area of coal mines, characterized in that: It includes a gas source system, a material conveying system, a gas supplementing system and a goaf receiving system; The gas source system includes nitrogen gas cylinders, carbon dioxide gas cylinders, a gas proportioning device, a gas storage tank, a cold dryer and a gas conveying pipeline. The nitrogen gas cylinders and carbon dioxide gas cylinders are connected to the gas proportioning device, the gas proportioning device is connected to the gas storage tank, the gas storage tank is connected to the cold dryer, and the cold dryer is connected to the gas conveying pipeline; The material conveying system includes a hopper, a sending silo pump, a control valve and a material conveying pipeline. The discharge port of the hopper is connected to the control valve through the sending silo pump, and the control valve is connected to the material conveying pipeline; The gas conveying pipeline is communicated with the material conveying pipeline; The gas supplementing system includes a gas supplementing pipeline. The gas supplementing pipeline and the material conveying pipeline are both connected to a Y-shaped vertical conveying pipeline; The Y-shaped vertical conveying pipeline is connected to the goaf receiving system; The goaf receiving system includes a goaf simulation device filled with broken rock simulation particles. The bottom end of the Y-shaped vertical conveying pipeline extends deep into the goaf simulation device; A dust processor is arranged at the top of the goaf simulation device.

2. The experimental system for long-distance conveying of fly ash from power plant flue gas to fill goaf in coal mines according to claim 1, characterized in that: A first flow regulating device and a second flow regulating device are arranged on the gas conveying pipeline. The inlet end of the gas conveying pipeline is connected to the cold dryer; One end of the material conveying pipeline is connected to the control valve, and a mixing chamber is also arranged at this end. The outlet end of the gas conveying pipeline is communicated with the material conveying pipeline through the mixing chamber, and the other end of the material conveying pipeline is connected to the Y-shaped vertical conveying pipeline.

3. An experimental system for filling gob areas of coal mines with fly ash transported over long distances from the flue gas of a power plant according to claim 2, characterized in that: The inlet end of the gas supplementing pipeline is connected to the gas conveying pipeline, and the connection point of the gas supplementing pipeline and the gas conveying pipeline is between the first flow regulating device and the second flow regulating device; A third flow regulating device is also arranged on the gas supplementing pipeline; The first flow regulating device, the second flow regulating device and the third flow regulating device all include a flowmeter, a pressure transmitter and a regulating valve; The gas conveying pipeline and the gas supplementing pipeline are both stainless steel pipelines.

4. An experimental system for long-distance conveying of fly ash from power plant flue gas to fill the gob area of coal mines according to claim 1, characterized in that: The goaf simulation device is arranged in layers and is stacked up and down by cuboids with open tops, specifically including the uppermost cuboid, several middle cuboids and the lowermost cuboid, and broken rock simulation particles are filled in each cuboid; A simulated roadway is arranged at the center of the lowermost cuboid along its length direction, and several first ventilation holes are arranged on both sides of the simulated roadway; Several second ventilation holes are arranged at the bottoms of the uppermost cuboid and several middle cuboids, and a sealing plate is arranged at the top of the uppermost cuboid.

5. An experimental system for transporting fly ash from a power plant flue gas over a long distance to fill a mined-out area of a coal mine according to claim 4, characterized in that: The Y-shaped vertical conveying pipeline is located at the center of the goaf simulation device, and the bottom of the Y-shaped vertical conveying pipeline is inserted into the middle position of the simulated roadway; Insertion holes for the Y-shaped vertical conveying pipeline to be inserted are arranged at corresponding positions on the sealing plate, the bottoms of the uppermost cuboid, several middle cuboids, and the top of the simulated roadway.

6. The experimental system for filling goafs of coal mines with fly ash transported over a long distance from flue gas of power plants according to claim 5, characterized in that: Observation ports are arranged around the lowermost cuboid, and on both sides of several middle cuboids and the uppermost cuboid corresponding to the simulated roadway. Handles for easy handling are arranged on the other two sides of several middle cuboids and the uppermost cuboid.

7. An experimental system for filling goafs of coal mines with fly ash transported over a long distance from the flue gas of a power plant according to claim 3, characterized in that: It also includes a three-dimensional laser scanner for scanning the surface of each layer of the goaf simulation device after fly ash filling; the first flow regulating device, the second flow regulating device, the third flow regulating device, the control valve and the three-dimensional laser scanner are all connected to the PLC control device.

8. An experimental method for simulating the long-distance transportation of fly ash from power plant flue gas to fill the gob area of coal mines, using the experimental system described in any one of claims 1-7, characterized in that The following steps are involved: (1) nitrogen in a nitrogen cylinder and carbon dioxide in a carbon dioxide cylinder are transported to a gas proportioning device, and the proportioned mixed gas in the gas proportioning device is stored in a gas storage tank; (2) The mixed gas in the gas storage tank is cooled and dried by a cold dryer and then transported through a gas delivery pipeline; a first flow regulating device is provided on the gas delivery pipeline, and a flow meter in the first flow regulating device is used to monitor the change of the gas flow in the gas delivery pipeline in real time, and a pressure transmitter in the first flow regulating device is used to adjust the pressure in the gas delivery pipeline; the gas delivery pipeline is connected to the material delivery pipeline and the air supply pipeline respectively; (3) The fly ash stored in the hopper enters the sending bin pump, which closes the feed port and starts to inflate and pressurize, then opens the discharge port to discharge the material through the lower control valve and sends it to the material conveying pipeline, and is transported with the mixed gas in the material conveying pipeline; the flow rate of the mixed gas is controlled by adjusting the second flow regulating device, and the control valve is adjusted to transport the fly ash with a high solid-gas ratio in the material conveying pipeline; (4) Part of the mixed gas in the gas delivery pipeline is also transported through the gas supply pipeline, and the pressure in the gas supply pipeline is adjusted by the pressure transmitter in the third flow regulating device to increase the flow rate of the mixed gas in the gas supply pipeline; (5) The fly ash in the material conveying pipeline and the mixed gas in the air supply pipeline are mixed through the Y-shaped vertical conveying pipeline in the goaf receiving system and transported to the simulated tunnel in the goaf simulation device, diffused to the goaf through the simulated tunnel, and the goaf area is inerted and filled; the fly ash smoke flow is fully circulated in the goaf and then purified by the dust processor at the top and discharged.

9. An experimental method for simulating the long-distance transportation of fly ash from power plant flue gas to fill the gob area of coal mines according to claim 8, characterized in that The following steps are also included: (6) Observe the flow and diffusion of fly ash smoke in the goaf through the observation port; (7) After the experiment is completed, the goaf simulation device is disassembled, observed from top to bottom, and scanned by a three-dimensional laser scanner; the fly ash delivery volume in the material conveying pipeline and the mixed gas flow rate in the air supply pipeline are continuously optimized through experiments.

10. An experimental method for simulating the long-distance transportation of fly ash from power plant flue gas to fill the goaf of coal mines according to claim 8, characterized in that The following steps are also included: (8) The fly ash mass flow rate M of the material conveying system and the mixed gas flow rate Q of the air supply system are collected in real time through the PLC control device, so that the solid-gas ratio S=M / Q is always maintained within the preset threshold range; (9) Continuously adjust the solid-gas ratio and the particle size combination of the crushed rock simulation particles filled in the goaf simulation device to conduct goaf filling experiments, and repeat each group of experiments multiple times; (10) After the experiment, the goaf simulation device was disassembled and two-dimensional laser scanning was performed layer by layer; the scanning data was imported into the modeling software to generate a three-dimensional point cloud model; the grid cells were divided and the filling degree of each grid cell was calculated; (11) Calculate the filling degree C and filling range R, where filling degree C = filling volume / void volume of goaf, and filling range R = maximum diffusion distance; (12) Establish a quantitative relationship model for the solid-gas ratio S, the simulated particle size D of broken rock, the filling degree C, and the filling range R: C = k1·(S / D) n + b R = k2·lnS + m·D where k1, k2, n, b, and m are experimental fitting coefficients; Use multiple regression analysis to fit the parameter relationship and obtain the experimental fitting coefficients; (13) In practical engineering applications, when new solid-gas ratio and goaf rock particle size data are obtained, input them into the trained model to obtain the corresponding predicted values of the filling degree and filling range, providing data support for on-site implementation.

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