A device and method for testing the water retention and cooling performance of thickened slurry

Abstract

The present invention discloses a testing device and method for the water retention and cooling performance of thickened slurry, wherein a gas regulating device is used to simulate the goaf environment; a heating and rotating device is used to simulate three different stages of coal spontaneous combustion; at the same time, a rotating drive motor is used to drive the coal sample to rotate, and a slurry smearing device drives an automatic slurry brush to swing through an electric slider and a slurry conduit, and the thickened slurry is evenly smeared and covered on the surface of the coal sample in combination with the rotation of the coal sample and the swing of the automatic slurry brush; finally, a monitoring device records the water retention parameters of the three stages of the thickened slurry for preventing and controlling coal spontaneous combustion through an infrared thermal imager, and evaluates the water retention of the thickened slurry by establishing a specific formula in combination with the water loss obtained by the weighing device, and obtains the evaluation results of the water retention and cooling performance of different thickened slurries in different stages of coal spontaneous combustion, thereby providing data reference for the subsequent selection of thickened slurry proportion and grouting amount for injection into the actual goaf according to the evaluation results.

Description

Technical Field

[0001] The present invention relates to a slurry performance testing device and method, in particular to a testing device and method for the water retention and cooling performance of thickened slurry, belonging to the technical field of thickened slurry performance testing. Background Art

[0002] Coal is one of my country's primary energy resources, mined in vast quantities. As coal mining efficiency improves, the amount of coal left in goafs increases. Due to the characteristics of coal and the natural environment during production, this leftover coal within goafs is prone to spontaneous combustion. To prevent and control spontaneous combustion in goafs, it's crucial to seal the internal fissures within the crushed coal to block the oxygen supply.

[0003] Therefore, grouting fire prevention and extinguishing technology is often used on-site in coal mines. While conventional grouting fire prevention and extinguishing technology is simple, fast, and easy to operate, it requires a large amount of water to suspend the grouting material. The slurry is also prone to sedimentation and pipe blockage during pipeline operation, causing severe wear and tear on the transportation pipeline. It also has limited effectiveness in controlling spontaneous combustion of coal in goafs. In response to the problems of existing grouting fire prevention and extinguishing technology, such as easy solid-liquid separation, severe water loss, and poor coverage and accumulation, some researchers have attempted to enhance the suspension and fire prevention properties of the grouting material by adding thickeners to the grouting material to produce a thickened slurry, with some success. However, after the thickened slurry is injected into the goaf, the water-retaining and cooling effect of the thickened slurry in preventing and extinguishing fire cannot be observed in the goaf, resulting in the inability to know the changes in the water-retaining and cooling performance of the thickened slurry at different stages of coal spontaneous combustion. The injection effect of the thickened slurry can only be determined by detecting whether there is coal spontaneous combustion in the goaf after grouting for a period of time. In this way, it is impossible to adopt corresponding thickened slurry components and grouting amounts for different coal qualities at different stages of coal spontaneous combustion, so that there is no data reference each time the thickened slurry is grouted, and the grouting amount can only be determined based on experience.

[0004] Therefore, how to provide a slurry performance testing device and method that can test the water retention and cooling performance of different thickened slurries injected into the same goaf at different stages of coal spontaneous combustion, obtain the water retention and cooling performance evaluation results of different thickened slurries at different stages of coal spontaneous combustion, and thus provide data reference for the subsequent selection of thickened slurry ratio and grouting volume for injection into actual goaf based on the evaluation test results, is one of the research directions of this industry. Summary of the Invention

[0005] In response to the problems existing in the above-mentioned prior art, the present invention provides a testing device and method for the water-retention and cooling performance of thickened slurries, which can test the water-retention and cooling performance of different thickened slurries injected into the same goaf at different stages of coal spontaneous combustion, and obtain evaluation results of the water-retention and cooling performance of different thickened slurries at different stages of coal spontaneous combustion, thereby providing data reference for subsequent selection of thickened slurry proportions and grouting volumes for injection into actual goafs based on the test and evaluation results.

[0006] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is: a testing device for the water retention and cooling performance of thickened slurry, comprising a box, a weighing device, a heating and rotating device, a monitoring device and a slurry applying device;

[0007] The box body is provided with a test chamber and a power supply chamber; a sealed door is provided on the box body, and the test chamber is connected to the outside of the box body when the sealed door is opened; the weighing device is placed at the bottom of the test chamber and is used to weigh the coal sample;

[0008] The heating and rotating device includes a heater, a rotary drive motor and a lifting mechanism, the lifting mechanism includes a lifting guide rod and a support frame, the lifting guide rods are two, the two lifting guide rods are fixed parallel to each other on the side wall of the power supply chamber, the outer surface of each lifting guide rod is provided with a sliding rack along the axial direction, the support frame is located between the two lifting guide rods, and a plurality of rotating gears are installed on the support frame, the support frame is engaged with the sliding racks of the two lifting guide rods through each rotating gear, one of the rotating gears is coaxially connected to the lifting motor, when the lifting motor rotates, the rotating gear rotates to make it move along the sliding rack, so that the support frame moves between the two lifting guide rods; one end of the heater is inserted into the coal sample, and the other end is connected to the output shaft of the rotary drive motor for heating and controlling the coal sample; the rotary drive motor is used to drive the coal sample to rotate;

[0009] The monitoring device is installed in the test chamber and is used to collect data on the entire process of the coal sample after it is coated with the thickened slurry, and to monitor the oxygen concentration and temperature in the test chamber in real time;

[0010] The slurry smearing device includes a feed pipe, an agitator, a delivery pipe, a sliding rod, an electric slider, an automatic slurry discharging brush and a slurry conduit. The feed pipe is installed in the power supply room, one end of which extends out of the box body and the other end extends into the test room, and is used to deliver the thickened slurry to the agitator; the agitator is installed on the side of the test room, and one end of which is connected to the other end of the feed pipe and the other end is connected to the delivery pipe, and is used to stir the thickened slurry injected by the feed pipe and deliver it to the delivery pipe; one end of the slurry conduit is hinged to the outside of the delivery pipe and is connected to the inside of the delivery pipe through a hose; the other end of the slurry conduit is hinged to the upper part of the automatic slurry discharging brush and is connected to the The automatic slurry discharging brush is internally connected and is used to transport the thickened slurry in the feed pipe to the automatic slurry discharging brush; the automatic slurry discharging brush includes a slurry cavity and multiple brush tubes, and the multiple brush tubes are arranged side by side at the lower part of the slurry cavity and are all connected to the inside of the slurry cavity. The automatic slurry discharging brush is used to output the thickened slurry to the surface of the coal sample; the sliding rod is horizontally fixed under the agitator, and the electric slider is installed on the sliding rod and can move on the sliding rod. The electric slider is hinged to the slurry conduit through a swinging guide rod. When the coal sample rotates, the electric slider moves back and forth on the sliding rod, so that the swinging guide rod and the slurry conduit drive the automatic slurry discharging brush to swing, and the thickened slurry is evenly applied to the surface of the coal sample.

[0011] Furthermore, the system also includes a gas regulating device, which includes a gas storage chamber, nitrogen pipelines, and oxygen pipelines. The gas storage chamber is installed at the top of the test chamber, with a gas injection port at the bottom of the gas storage chamber. The nitrogen pipeline and oxygen pipeline are both installed in the upper part of the box. One end of the nitrogen pipeline extends into the box and connects to the gas storage chamber, and the other end is connected to a nitrogen source. One end of the oxygen pipeline extends into the box and connects to the gas storage chamber, and the other end is connected to an oxygen source. The gas regulating device can simulate the oxygen concentration in the goaf, making the test more similar to the actual process, thereby obtaining more realistic data.

[0012] Furthermore, the heater includes a rotary knob and three heating tubes. Each of the three heating tubes runs from one end of the coal sample to the other, and is arranged in a herringbone pattern across the cross-section of the coal sample. The rotary knob is connected to the three heating tubes to control their heating temperature. This heater structure not only heats the coal sample evenly but also ensures greater stability during subsequent rotation, facilitating the application of the thickened slurry.

[0013] Furthermore, the monitoring device includes an infrared thermal imager, an oxygen concentration sensor, a temperature sensor, a gas concentration display panel, and a temperature display panel. The infrared thermal imager is installed in the test chamber and is used to collect data on the entire process of applying the thickened slurry to the coal sample. The oxygen concentration sensor and temperature sensor are both installed in the test chamber, and the gas concentration display panel and temperature display panel are installed on the outer surface of the box. The oxygen concentration sensor is connected to the gas concentration display panel to obtain and display the real-time oxygen concentration in the test chamber. The temperature sensor is connected to the temperature display panel to obtain and display the real-time temperature in the test chamber. Using this monitoring device, the required monitoring data can be obtained, ensuring the acquisition of test data and the smooth progress of the test.

[0014] Furthermore, there are two slurry conduits. Using two slurry conduits can not only better transport the thickened slurry, but also ensure the stability of the automatic slurry discharge brush when it swings.

[0015] Furthermore, a plurality of transverse through holes are provided on the side wall of the brush tube, and this structure facilitates more uniform application of the thickened slurry to the surface of the coal sample.

[0016] Furthermore, the outer surface of the electric slider adopts 1550 series polymer foam resin insulation cotton to insulate the electric slider, which can prevent the heat generated after the electric slider moves from interfering with the results of the infrared thermal imager, ensuring that the data obtained is more accurate.

[0017] The working method of the above-mentioned testing device for the water retention and cooling performance of thickened slurry comprises the following specific steps:

[0018] A. Test Preparation: First, collect the residual coal from the simulated goaf and process it into multiple cylindrical coal samples. At the same time, obtain the oxygen concentration in the simulated goaf. Then, select one of the cylindrical coal samples, connect it to the heater, and place it on the electronic scale. Then, set the heating temperature values ​​for the simulated low-temperature oxidation stage (i.e., latent period), self-heating stage (i.e., self-heating period), and spontaneous combustion stage (i.e., spontaneous combustion period) to complete the test preparation.

[0019] B. Test on water retention and cooling performance of thickened slurry in low temperature oxidation stage:

[0020] ① According to the oxygen concentration obtained in step A, nitrogen and oxygen are transported into the gas storage chamber through the nitrogen pipeline and the oxygen pipeline. The nitrogen and oxygen are mixed in the gas storage chamber and then injected into the test chamber through the gas injection port. The oxygen concentration in the test chamber is detected in real time by the oxygen concentration sensor, and the oxygen concentration in the test chamber is observed through the gas concentration display panel. The injection amount of nitrogen and oxygen is adjusted until the oxygen concentration in the test chamber reaches the oxygen concentration obtained in step A, and the injection of nitrogen and oxygen is stopped to complete the simulation of the oxygen concentration in the goaf; then the temperature of the heater is adjusted by turning the rotary knob to heat the coal sample, and the temperature in the test chamber is detected in real time by the temperature sensor, and the temperature in the test chamber is observed through the temperature display panel until the temperature reaches the heating temperature value set in the low-temperature oxidation stage in step A. At this time, the heater is stopped to complete the temperature simulation process;

[0021] ② Inject thickened slurry through the feed pipe and start the agitator to fully stir the thickened slurry in the agitator. Then, the thickened slurry is transported through the feed pipe and then delivered to the slurry conduit. Then, start the lifting motor to drive the coal sample upward as a whole through the support frame so that the coal sample does not contact the electronic scale. Then start the rotary drive motor to drive the heater to rotate the coal sample at a low speed. At the same time, control the electric slider to start reciprocating on the slide rod, so that the swing guide rod and the slurry conduit drive the automatic slurry brush to swing, and then the automatic slurry brush contacts the surface of the coal sample. Through the dual effects of swinging and rotating, the thickened slurry is evenly applied to the surface of the coal sample.

[0022] ③ After continuous application for a period of time, stop the agitator, electric slider and rotary drive motor, and use the lifting motor to make the coal sample freely contact with the electronic scale again. The electronic scale records the weight of the coal sample after the thickening slurry is applied, and weighs its weight in real time in the subsequent process to obtain the water loss of the thickened slurry; the temperature display panel records the changes in the simulated coal spontaneous combustion temperature in the test room; at the same time, start the infrared thermal imager to record the entire process of preventing and controlling coal spontaneous combustion after the thickening slurry is applied. The recorded data include the stratification degree of the thickened slurry on the coal sample surface, the moisture distribution and the rate of change of the apparent density of the coal sample over time. Combined with the water loss obtained by the electronic scale, the five indicators of coal spontaneous combustion temperature T, slurry stratification degree δ, water loss G, moisture distribution M and the rate of change of the apparent density of the coal sample over time ρ are summarized. The data of the five indicators are standardized to determine the weight of each indicator. Finally, the final score is calculated. The water retention of the thickened slurry in the process of preventing and controlling coal spontaneous combustion in the current low-temperature oxidation stage of the goaf is determined based on the comprehensive score.

[0023] C. Test of water retention and cooling performance of thickened slurry during the self-heating stage: Select a coal sample from step A again. The subsequent test process is the same as step B, with the only difference being that the coal sample is heated to the heating temperature set in step A during the self-heating stage to complete the temperature simulation process, thereby determining the water retention of the thickened slurry during the current goaf self-heating stage to prevent coal spontaneous combustion;

[0024] D. Testing the water retention and cooling performance of the thickened slurry during the spontaneous combustion stage: Select a coal sample from step A again. The subsequent testing process is the same as step B, with the only difference being that the coal sample is heated to the heating temperature set in step A during the spontaneous combustion stage to complete the temperature simulation process, thereby determining the water retention of the thickened slurry during the current goaf spontaneous combustion stage to prevent and control coal spontaneous combustion;

[0025] E. Obtain the water retention performance of the thickened slurry throughout the entire coal spontaneous combustion process: Based on the water retention performance tests of the thickened slurry in the three stages of steps B to D, the water retention of the thickened slurry in the process of preventing and controlling coal spontaneous combustion at various stages of the current goaf can be determined; after adjusting the proportion of the thickened slurry, repeat steps A to E multiple times to obtain the water retention of different thickened slurries in the process of preventing and controlling coal spontaneous combustion at various stages of the current goaf.

[0026] Furthermore, the specific process of calculating the final score in step ③ is as follows:

[0027] 1) Assume that m objects are comprehensively evaluated using n indicators, and the j-th indicator data of the evaluated object i is z ij , the matrix composed of all indicator data is (Z1, Z2, ..., Z n )=(Z ij ) m×n , where Z j =(z 1j ,z 2j ,…,z mj ) T represents the value of the j-th indicator;

[0028] 2) Find out the abnormal evaluation values ​​under each evaluation index;

[0029] Define the normal evaluation value to meet:

[0030]

[0031] in Find out the abnormal evaluation values ​​under each evaluation index, namely:

[0032]

[0033] The positive indicator evaluation value of the defined indicator is:

[0034]

[0035] The evaluation value of the reverse indicator with a small definition indicator is:

[0036]

[0037] Among them, μ a =2.06;

[0038] 3) Correct abnormal evaluation values;

[0039] Moderation indicators are processed as follows:

[0040]

[0041] Positive indicators are processed as follows:

[0042]

[0043] The reverse indicator is processed as follows:

[0044]

[0045] 5) Measure the correction rate of the evaluation value;

[0046]

[0047] When all ΔZ under index j (k+1) ij All satisfy ΔZ (k+1) ij When ≤0.001, i=1,2,…,m,j=1,2,…,n

[0048]

[0049] It is considered that there is no abnormal evaluation value under the j indicator, and the evaluation value correction is completed;

[0050] 6) Standardize and dimensionless the evaluation value after abnormal processing:

[0051]

[0052] Among them, Z′ ij is the evaluation value after abnormal processing, Z′ j is the average value after abnormal processing, s′ j is the standard deviation after abnormal processing, X ij is the standardized evaluation value;

[0053] 7) The weight of each indicator is recorded as w = (w1, w2, ..., w n ) T , calculate the weights using the multiple correlation coefficient;

[0054] Assume that the regression results of the j-th indicator and the remaining indicators are:

[0055]

[0056] Where j = 1, 2, ..., n, then the multiple correlation coefficient between the j-th indicator and the remaining indicators is:

[0057]

[0058] According to the principle that the smaller the correlation coefficient, the greater the weight, the weight of the j-th indicator is constructed as follows:

[0059]

[0060] 8) The comprehensive evaluation results are:

[0061] Y=(y1,y2,…,y n ) T

[0062] Where, Y = Xw, The final score can be calculated based on this formula.

[0063] Furthermore, the temperature set in the low-temperature oxidation stage is 40°C±1°C, the temperature set in the self-heating stage is 65°C±1°C, and the temperature set in the self-ignition stage is 85°C±1°C.

[0064] Compared with the prior art, the present invention adopts a combination of a box, a weighing device, a heating and rotating device, a monitoring device, a gas regulating device and a slurry coating device, wherein the gas regulating device controls the oxygen content in the environment inside the box by adjusting the gas output of the oxygen pipeline and the nitrogen pipeline, thereby simulating the goaf environment; the heating and rotating device heats the coal sample through a heater, and simulates the three different stages of coal spontaneous combustion (i.e., low-temperature oxidation stage, self-heating stage and spontaneous combustion stage) at different temperatures, so that the experiment is closer to the actual situation; at the same time, the coal sample can be driven to rotate by a rotating drive motor, and cooperate with the slurry coating device. The slurry coating device drives the automatic slurry brush to swing through the electric slider and the slurry conduit, and transports the thickened slurry to the automatic slurry brush through the slurry conduit through the agitator. The automatic slurry brush is rotated by the rotation of the coal sample and the swinging of the automatic slurry brush. The thickened slurry is evenly applied to the outer surface of the coal sample, which can ensure that the thickened slurry is evenly covered on the surface of the coal sample; finally, the monitoring device records the water retention parameters of the thickened slurry in the three stages of preventing and controlling coal spontaneous combustion through an infrared thermal imager, and obtains the water loss through a weighing device. Finally, a specific formula is used to comprehensively evaluate the water retention of the thickened slurry in the process of preventing and controlling coal spontaneous combustion in each stage based on five indicators, namely, coal spontaneous combustion temperature, slurry stratification, water loss, moisture distribution, and the rate of change of coal sample apparent density over time; through the above process, it can be seen that the present invention has the advantages of simple operation and easy layout of the device structure; by establishing a specific formula to evaluate the water retention of the thickened slurry, the water retention and cooling performance evaluation results of different thickened slurries in different stages of coal spontaneous combustion are obtained, thereby providing data reference for the subsequent selection of thickened slurry proportions and grouting amounts for injection into actual goafs according to the evaluation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0066] Figure 2 It is a schematic diagram of the internal structure of the present invention;

[0067] Figure 3 It is a schematic structural diagram of the coal sample in the present invention;

[0068] Figure 4 It is a structural diagram of the brush tube in the present invention;

[0069] Figure 5 It is a structural schematic diagram of the lifting mechanism in the present invention.

[0070] In the figure: 1. Box; 2. Test chamber; 3. Coal sample; 4. Electronic scale; 5. Heater; 6. Rotating knob; 7. Gas concentration display panel; 8. Temperature display panel; 9. Feed pipe; 10. Infrared thermal imager; 11. Gas storage chamber; 12. Gas injection port; 13. Slurry conduit; 14. Sliding rod; 15. Swinging guide rod; 16. Automatic slurry brush; 17. Rotary drive motor; 18. Oxygen pipeline; 19. Nitrogen pipeline; 20. Agitator; 21. Power supply chamber; 22. Horizontal through hole; 23. Brush tube; 24. Electric slider; 25. Support frame; 26. Sliding rack; 27. Lifting guide rod; 28. Rotating gear. DETAILED DESCRIPTION

[0071] The present invention will be further described below.

[0072] like Figure 1 and 2 As shown, a test device for the water retention and cooling performance of thickened slurry includes a box 1, a weighing device, a heating and rotating device, a monitoring device, a gas regulating device and a slurry applying device;

[0073] The box body is provided with a test chamber 2 and a power supply chamber 21; a sealed door is provided on the box body 1, and the test chamber 2 is connected to the outside of the box body when the sealed door is opened; the weighing device is placed at the bottom of the test chamber 2 and is used to weigh the coal sample; the weighing device is an electronic scale 4;

[0074] The heating and rotating device includes a heater 5, a rotation drive motor 6 and a lifting mechanism. Figure 5 As shown, the lifting mechanism includes a lifting guide rod 27 and a support frame 25. There are two lifting guide rods 27, and the two lifting guide rods 27 are fixed parallel to each other on the side wall of the power supply chamber 21. The outer surface of each lifting guide rod 27 is provided with a sliding rack 26 along the axial direction. The support frame 25 is located between the two lifting guide rods 27. A plurality of rotating gears 28 are installed on the support frame 25. The support frame 25 is engaged with the sliding racks 26 of the two lifting guide rods 27 through each rotating gear 28. One of the rotating gears 28 is coaxially connected to the lifting motor. When the lifting motor rotates, the rotating gear 28 rotates to move it along the sliding rack 26, so that the support frame 25 moves between the two lifting guide rods 27; one end of the heater 25 is inserted into the coal sample 3, and the other end is connected to the output shaft of the rotary drive motor 17, so as to control the heating of the coal sample 3; the rotary drive motor 17 is used to drive the coal sample 3 to rotate;

[0075] The monitoring device is installed in the test chamber 2 and is used to collect data on the entire process of applying the thickened slurry to the coal sample 3, as well as to monitor the oxygen concentration and temperature in the test chamber 2 in real time. The monitoring device includes an infrared thermal imager 10, an oxygen concentration sensor, a temperature sensor, a gas concentration display panel 7, and a temperature display panel 8. The infrared thermal imager 10 is installed in the test chamber 2 and is used to collect data on the entire process of applying the thickened slurry to the coal sample 3. The oxygen concentration sensor and the temperature sensor are both installed in the test chamber 2. The gas concentration display panel 7 and the temperature display panel 8 are installed on the outer surface of the box 1. The oxygen concentration sensor is connected to the gas concentration display panel 7 to obtain and display the real-time oxygen concentration in the test chamber 2. The temperature sensor is connected to the temperature display panel 8 to obtain and display the real-time temperature in the test chamber 2. Using this monitoring device, the required monitoring data can be obtained, ensuring the acquisition of test data and the smooth progress of the test.

[0076] The slurry smearing device includes a feed pipe 9, an agitator 20, a delivery pipe, a slide rod 14, an electric slider 24, an automatic slurry discharge brush 16 and a slurry conduit 13. The feed pipe 9 is installed in the power supply room 21, one end of which extends out of the box body 1 and the other end extends into the test chamber 2, for conveying thickened slurry to the agitator 20; the agitator 20 is installed on the side of the test chamber 2, and one end of which is connected to the other end of the feed pipe 9 and the other end is connected to the delivery pipe, for stirring the thickened slurry injected by the feed pipe 9 and conveying it to the delivery pipe; one end of the slurry conduit 13 is hinged to the outside of the delivery pipe and is connected to the inside of the delivery pipe through a hose; the other end of the slurry conduit 13 is hinged to the upper part of the automatic slurry discharge brush 16 and is connected to the inside of the automatic slurry discharge brush 16 through a hose, for conveying the thickened slurry in the delivery pipe to the automatic slurry discharge brush 16; the automatic slurry discharge brush 16 includes a slurry cavity and a plurality of brush pipes 23, such as Figure 4 As shown, the side wall of the brush tube 23 is provided with a plurality of transverse through holes 22; the plurality of brush tubes 23 are arranged side by side at the lower part of the slurry chamber and are all connected to the inside of the slurry chamber, and the automatic slurry brush 16 is used to output the thickened slurry to the surface of the coal sample 3; the slide bar 14 is horizontally fixed below the agitator 20, and the electric slider 24 is mounted on the slide bar 14 and can move on the slide bar 14. The electric slider 24 is hinged to the slurry conduit 13 through the swing guide rod 15. When the coal sample 3 rotates, the electric slider 24 moves back and forth on the slide bar 14, so that the swing guide rod 15 and the slurry conduit 13 drive the automatic slurry brush 16 to swing, and the thickened slurry is evenly applied to the surface of the coal sample 3; there are two slurry conduits 13. The use of two slurry conduits 13 can not only better transport the thickened slurry, but also ensure the stability of the automatic slurry brush 16 when swinging.

[0077] The gas regulating device includes a gas storage chamber 11, a nitrogen pipeline 19, and an oxygen pipeline 18. The gas storage chamber 11 is installed at the top of the test chamber 2, and a gas injection port 12 is provided at the bottom of the gas storage chamber 11. The nitrogen pipeline 19 and the oxygen pipeline 18 are both installed at the top of the box 1. One end of the nitrogen pipeline 19 extends into the box 1 and connects to the gas storage chamber 11, and the other end is connected to a nitrogen source. The oxygen pipeline 18 extends into the box 1 and connects to the gas storage chamber 11, and the other end is connected to an oxygen source. The gas regulating device can simulate the oxygen concentration in the goaf, making the test closer to the actual process and thus obtaining more realistic data.

[0078] As an improvement to the present invention, the heater 5 includes a rotary knob 6 and three heating tubes. Each of the three heating tubes extends from one end of the coal sample 3 to the other, and is arranged in a herringbone pattern across the cross-section of the coal sample 3. The rotary knob 6 is connected to the three heating tubes to control their heating temperature. This heater structure not only uniformly heats the coal sample 3 but also provides greater stability during subsequent rotation, facilitating the application of the thickened slurry.

[0079] As another improvement of the present invention, the outer surface of the electric slider 24 adopts 1550 series polymer foam resin insulation cotton to insulate the electric slider 24. This can prevent the heat generated after the electric slider 24 moves from interfering with the results of the infrared thermal imager 10, ensuring that the data obtained is more accurate.

[0080] The working method of the above-mentioned testing device for the water retention and cooling performance of thickened slurry comprises the following specific steps:

[0081] A. Test preparation: First collect the residual coal in the simulated goaf, such as Figure 3 As shown, multiple cylindrical coal samples 3 are processed, and the oxygen concentration in the desired simulated goaf is obtained at the same time. Then, one of the cylindrical coal samples 3 is selected, connected to the heater 5, and placed on the electronic scale 4. Then, the temperature of the simulated low-temperature oxidation stage (i.e., the incubation period) is set to 40°C ± 1°C, the temperature of the self-heating stage (i.e., the self-heating period) is set to 65°C ± 1°C, and the temperature of the self-ignition stage (i.e., the self-ignition period) is set to 85°C ± 1°C, and the test preparation is completed;

[0082] B. Test on water retention and cooling performance of thickened slurry in low temperature oxidation stage:

[0083] ① According to the oxygen concentration obtained in step A, nitrogen and oxygen are transported to the gas storage chamber 11 through the nitrogen pipeline 19 and the oxygen pipeline 18. After the nitrogen and oxygen are mixed in the gas storage chamber 11, they are injected into the test chamber 2 through the gas injection port 12. The oxygen concentration in the test chamber 2 is detected in real time by the oxygen concentration sensor, and the oxygen concentration in the test chamber 2 is observed through the gas concentration display panel 7. The injection amount of nitrogen and oxygen is adjusted until the oxygen concentration in the test chamber 2 reaches the oxygen concentration obtained in step A, and the injection of nitrogen and oxygen is stopped to complete the simulation of the oxygen concentration in the goaf; then the temperature of the heater 5 is adjusted by rotating the rotary knob 6 to heat the coal sample 3, and the temperature in the test chamber 2 is detected in real time by the temperature sensor, and the temperature in the test chamber 2 is observed through the temperature display panel 8 until the temperature reaches the heating temperature value set in the low-temperature oxidation stage in step A. At this time, the heater is stopped to complete the temperature simulation process;

[0084] ② Inject the thickened slurry through the feed pipe 9 and start the stirrer 20 to fully stir the thickened slurry in the stirrer 20 and transport it through the feed pipe to the slurry conduit 13. Then start the lifting motor to drive the coal sample 2 to move up 1 cm as a whole through the support frame 25, so that the coal sample 2 does not contact the electronic scale 4. Then start the rotary drive motor 6 to make the heater 5 drive the coal sample 3 to rotate at a low speed. At the same time, control the electric slider 24 to start reciprocating movement on the slide bar 14, so that the swing guide rod 15 and the slurry conduit 13 drive the automatic slurry brush 16 to swing, and then the automatic slurry brush 16 contacts the surface of the coal sample 3. Through the dual effects of swinging and rotating, the thickened slurry is evenly applied to the surface of the coal sample.

[0085] ③ After applying the thickened slurry for a period of time, the agitator 20, the electric slider 24 and the rotary drive motor 17 are stopped, and the coal sample 3 is brought into free contact with the electronic scale 4 again through the lifting motor. The weight of the coal sample 3 after the thickened slurry is currently applied is recorded by the electronic scale 4, and its weight is weighed in real time in the subsequent process to obtain the water loss of the thickened slurry; the temperature display panel 8 records the change of the simulated coal spontaneous combustion temperature in the test chamber 2; at the same time, the infrared thermal imager 10 is started to record the whole process of preventing and controlling the coal spontaneous combustion after the thickened slurry is applied. The recorded data include the stratification degree of the thickened slurry on the coal sample surface, the moisture distribution and the rate of change of the coal sample's apparent density over time. Combined with the water loss obtained by the electronic scale 4, five indicators are summarized, namely, the coal spontaneous combustion temperature T, the slurry stratification degree δ, the water loss G, the moisture distribution M and the rate of change of the coal sample's apparent density over time ρ. The five indicator data are standardized to determine the weight of each indicator and finally calculate the final score. The specific process is as follows:

[0086] 1) Assume that m objects are comprehensively evaluated using n indicators, and the j-th indicator data of the evaluated object i is z ij, the matrix composed of all indicator data is (Z1, Z2, ..., Z n )=(Z ij ) m×n , where Z j =(z 1j ,z 2j ,…,z mj ) T represents the value of the j-th indicator;

[0087] 2) Find out the abnormal evaluation values ​​under each evaluation index;

[0088] Define the normal evaluation value to meet:

[0089]

[0090] in Find out the abnormal evaluation values ​​under each evaluation index, namely:

[0091]

[0092] The positive indicator evaluation value of the defined indicator is:

[0093]

[0094] The evaluation value of the reverse indicator with a small definition indicator is:

[0095]

[0096] Among them, μ a =2.06;

[0097] 3) Correct abnormal evaluation values;

[0098] Moderation indicators are processed as follows:

[0099]

[0100] Positive indicators are processed as follows:

[0101]

[0102] The reverse indicator is processed as follows:

[0103]

[0104] 5) Measure the correction rate of the evaluation value;

[0105]

[0106] When all ΔZ under index j (k+1) ij All satisfy ΔZ (k+1)ij When ≤0.001, i=1,2,…,m,j=1,2,…,n

[0107]

[0108] It is considered that there is no abnormal evaluation value under the j indicator, and the evaluation value correction is completed;

[0109] 6) Standardize and dimensionlessly process the evaluation values ​​after abnormal processing;

[0110]

[0111] Among them, Z′ ij is the evaluation value after abnormal processing, Z′ j is the average value after abnormal processing, s′ j is the standard deviation after abnormal processing, X ij is the standardized evaluation value;

[0112] 7) The weight of each indicator is recorded as w = (w1, w2, ..., w n ) T , calculate the weights using the multiple correlation coefficient;

[0113] Assume that the regression results of the j-th indicator and the remaining indicators are:

[0114]

[0115] Where j = 1, 2, ..., n, then the multiple correlation coefficient between the j-th indicator and the remaining indicators is:

[0116]

[0117] According to the principle that the smaller the correlation coefficient, the greater the weight, the weight of the j-th indicator is constructed as follows:

[0118]

[0119] 8) The comprehensive evaluation results are:

[0120] Y=(y1,y2,…,y n ) T

[0121] Where, Y = Xw, The final score can be calculated according to this formula;

[0122] Finally, the water retention of the thickened slurry in the process of preventing and controlling coal spontaneous combustion at the low-temperature oxidation stage in the current goaf is determined based on the comprehensive score;

[0123] C. Test of water retention and cooling performance of thickened slurry in the self-heating stage: Select a coal sample 3 from step A again. The subsequent test process is the same as step B, except that when heating the coal sample 3, it is heated to the heating temperature value set in the self-heating stage in step A to complete the temperature simulation process, thereby determining the water retention of the thickened slurry in the process of preventing and controlling coal spontaneous combustion in the current goaf self-heating stage;

[0124] D. Test of water retention and cooling performance of thickened slurry during spontaneous combustion: Select a coal sample 3 from step A again. The subsequent test process is the same as step B, with the only difference being that the coal sample 3 is heated to the heating temperature set in step A during the spontaneous combustion stage to complete the temperature simulation process, thereby determining the water retention of the thickened slurry during the current goaf spontaneous combustion stage to prevent and control coal spontaneous combustion;

[0125] E. Obtain the water retention performance of the thickened slurry during the entire process of coal spontaneous combustion: Based on the water retention performance test of the thickened slurry in the three stages from steps B to D, the water retention of the thickened slurry in the process of preventing and controlling coal spontaneous combustion at various stages of coal spontaneous combustion in the current goaf can be determined; after adjusting the proportion of the thickened slurry, repeat steps A to E multiple times to obtain the water retention of different thickened slurries in the process of preventing and controlling coal spontaneous combustion at various stages of coal spontaneous combustion in the current goaf, providing data reference for the subsequent selection of the thickened slurry proportion for injection into the actual goaf.

[0126] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A device for testing the water retention and cooling performance of thickened slurry, characterized in that: It includes a box, a weighing device, a heating and rotating device, a monitoring device and a slurry applying device; The box body is provided with a test chamber and a power supply chamber; a sealed door is provided on the box body, and the test chamber is connected to the outside of the box body when the sealed door is opened; the weighing device is placed at the bottom of the test chamber and is used to weigh the coal sample; The heating and rotating device includes a heater, a rotary drive motor and a lifting mechanism, the lifting mechanism includes a lifting guide rod and a support frame, the lifting guide rods are two, and the two lifting guide rods are fixed parallel to each other on the side wall of the power supply room, and a sliding rack is provided on the outer surface of each lifting guide rod along the axial direction, and the support frame is located between the two lifting guide rods, and a plurality of rotating gears are installed on the support frame, and the support frame is meshed with the sliding racks of the two lifting guide rods through each rotating gear, and one of the rotating gears is coaxially connected to the lifting motor. When the lifting motor rotates, the rotating gear rotates to move it along the sliding rack, so that the support frame moves between the two lifting guide rods, and drives the coal sample up and down through the support frame, so that the coal sample contacts or does not contact the weighing device; one end of the heater is inserted into the coal sample, and the other end is connected to the output shaft of the rotary drive motor for heating and controlling the coal sample; the rotary drive motor is used to drive the coal sample to rotate; The monitoring device is installed in the test chamber and is used to collect data on the entire process of the coal sample after it is coated with the thickened slurry, and to monitor the oxygen concentration and temperature in the test chamber in real time; The slurry smearing device includes a feed pipe, an agitator, a delivery pipe, a sliding rod, an electric slider, an automatic slurry discharging brush and a slurry conduit. The feed pipe is installed in the power supply room, one end of which extends out of the box body and the other end extends into the test room, and is used to deliver the thickened slurry to the agitator; the agitator is installed on the side of the test room, and one end of which is connected to the other end of the feed pipe and the other end is connected to the delivery pipe, and is used to stir the thickened slurry injected by the feed pipe and deliver it to the delivery pipe; one end of the slurry conduit is hinged to the outside of the delivery pipe and is connected to the inside of the delivery pipe through a hose; the other end of the slurry conduit is hinged to the upper part of the automatic slurry discharging brush and is connected to the The automatic slurry discharging brush is internally connected and is used to transport the thickened slurry in the feed pipe to the automatic slurry discharging brush; the automatic slurry discharging brush includes a slurry cavity and multiple brush tubes, and the multiple brush tubes are arranged side by side at the lower part of the slurry cavity and are all connected to the inside of the slurry cavity. The automatic slurry discharging brush is used to output the thickened slurry to the surface of the coal sample; the sliding rod is horizontally fixed under the agitator, and the electric slider is installed on the sliding rod and can move on the sliding rod. The electric slider is hinged to the slurry conduit through a swinging guide rod. When the coal sample rotates, the electric slider moves back and forth on the sliding rod, so that the swinging guide rod and the slurry conduit drive the automatic slurry discharging brush to swing, and the thickened slurry is evenly applied to the surface of the coal sample.

2. The device for testing the water retention and cooling performance of thickened slurry according to claim 1, characterized in that: The testing device also includes a gas regulating device, which includes a gas storage chamber, a nitrogen pipeline and an oxygen pipeline. The gas storage chamber is installed at the top of the testing chamber, and a gas injection port is opened at the lower part of the gas storage chamber. The nitrogen pipeline and the oxygen pipeline are both installed at the upper part of the box body. One end of the nitrogen pipeline extends into the box body and is connected to the gas storage chamber, and the other end is connected to the nitrogen source; one end of the oxygen pipeline extends into the box body and is connected to the gas storage chamber, and the other end is connected to the oxygen source.

3. The device for testing the water retention and cooling performance of thickened slurry according to claim 1, characterized in that: The heater includes a rotating knob and three heating tubes. The three heating tubes all pass through the coal sample from one end to the other, and the three heating tubes are distributed in a herringbone shape on the cross section of the coal sample. The rotating knob is connected to the three heating tubes for controlling the heating temperature of the three heating tubes.

4. The device for testing the water retention and cooling performance of thickened slurry according to claim 1, characterized in that: The monitoring device includes an infrared thermal imager, an oxygen concentration sensor, a temperature sensor, a gas concentration display panel and a temperature display panel. The infrared thermal imager is installed in the test chamber and is used to collect data on the entire process of smearing the thickened slurry on the coal sample; the oxygen concentration sensor and the temperature sensor are both installed in the test chamber, and the gas concentration display panel and the temperature display panel are installed on the outer surface of the box. The oxygen concentration sensor is connected to the gas concentration display panel to obtain and display the real-time oxygen concentration in the test chamber; the temperature sensor is connected to the temperature display panel to obtain and display the real-time temperature in the test chamber.

5. The device for testing the water retention and cooling performance of thickened slurry according to claim 1, characterized in that: There are two slurry conduits.

6. The device for testing the water retention and cooling performance of thickened slurry according to claim 1, characterized in that: The side wall of the brush tube is provided with a plurality of transverse through holes.

7. The device for testing the water retention and cooling performance of thickened slurry according to claim 1, characterized in that: The outer surface of the electric slider adopts 1550 series polymer foamed resin insulation cotton to insulate the electric slider.

8. A method for operating the device for testing the water retention and cooling performance of thickened slurry according to any one of claims 1 to 7, characterized in that: The specific steps are: A. Test Preparation: First, collect the residual coal from the simulated goaf and process it into multiple cylindrical coal samples. At the same time, obtain the oxygen concentration in the simulated goaf. Then, select one of the cylindrical coal samples, connect it to a heater, and place it on a weighing device (an electronic scale). Then, set the heating temperature values ​​for the simulated low-temperature oxidation stage, self-heating stage, and spontaneous combustion stage respectively to complete the test preparation. B. Test on water retention and cooling performance of thickened slurry in low temperature oxidation stage: ① According to the oxygen concentration obtained in step A, nitrogen and oxygen are transported into the gas storage chamber through the nitrogen pipeline and the oxygen pipeline. The nitrogen and oxygen are mixed in the gas storage chamber and then injected into the test chamber through the gas injection port. The oxygen concentration in the test chamber is detected in real time by the oxygen concentration sensor, and the oxygen concentration in the test chamber is observed through the gas concentration display panel. The injection amount of nitrogen and oxygen is adjusted until the oxygen concentration in the test chamber reaches the oxygen concentration obtained in step A, and the injection of nitrogen and oxygen is stopped to complete the simulation of the oxygen concentration in the goaf; then the temperature of the heater is adjusted by turning the rotary knob to heat the coal sample, and the temperature in the test chamber is detected in real time by the temperature sensor, and the temperature in the test chamber is observed through the temperature display panel until the temperature reaches the heating temperature value set in the low-temperature oxidation stage in step A. At this time, the heater is stopped to complete the temperature simulation process; ② Inject thickened slurry through the feed pipe and start the agitator to fully stir the thickened slurry in the agitator. Then, the thickened slurry is transported through the feed pipe and then delivered to the slurry conduit. Then, start the lifting motor to drive the coal sample upward as a whole through the support frame so that the coal sample does not contact the electronic scale. Then start the rotary drive motor to drive the heater to rotate the coal sample at a low speed. At the same time, control the electric slider to start reciprocating on the slide rod, so that the swing guide rod and the slurry conduit drive the automatic slurry brush to swing, and then the automatic slurry brush contacts the surface of the coal sample. Through the dual effects of swinging and rotating, the thickened slurry is evenly applied to the surface of the coal sample. ③ After continuous application for a period of time, stop the agitator, electric slider and rotary drive motor, and use the lifting motor to make the coal sample freely contact with the electronic scale again. The electronic scale records the weight of the coal sample after the thickening slurry is applied, and weighs its weight in real time in the subsequent process to obtain the water loss of the thickening slurry; the temperature display panel records the changes in the simulated coal spontaneous combustion temperature in the test room; at the same time, start the infrared thermal imager to record the entire process of preventing and controlling coal spontaneous combustion after the thickening slurry is applied. The recorded data include the stratification degree of the thickening slurry on the coal sample surface, the moisture distribution and the rate of change of the coal sample's apparent density over time. Combined with the water loss obtained by the electronic scale, five indicators are summarized, namely, the coal spontaneous combustion temperature T, the slurry stratification degree δ, the water loss G, the moisture distribution M‍ and the rate of change of the coal sample's apparent density over time ρ. The five indicator data are standardized to determine the weight of each indicator. Finally, the final score is calculated. Based on the comprehensive score, the water retention of the thickening slurry in the process of preventing and controlling coal spontaneous combustion in the current low-temperature oxidation stage of the goaf is determined. C. Test of water retention and cooling performance of thickened slurry during the self-heating stage: Select a coal sample from step A again. The subsequent test process is the same as step B, with the only difference being that the coal sample is heated to the heating temperature set in step A during the self-heating stage to complete the temperature simulation process, thereby determining the water retention of the thickened slurry during the current goaf self-heating stage to prevent coal spontaneous combustion; D. Testing the water retention and cooling performance of the thickened slurry during the spontaneous combustion stage: Select a coal sample from step A again. The subsequent testing process is the same as step B, with the only difference being that the coal sample is heated to the heating temperature set in step A during the spontaneous combustion stage to complete the temperature simulation process, thereby determining the water retention of the thickened slurry during the current goaf spontaneous combustion stage to prevent and control coal spontaneous combustion; E. Obtain the water retention performance of the thickened slurry throughout the entire coal spontaneous combustion process: Based on the water retention performance tests of the thickened slurry in the three stages of steps B to D, determine the water retention of the thickened slurry in the process of preventing and controlling coal spontaneous combustion in various stages of coal spontaneous combustion in the current goaf; after adjusting the ratio of the thickened slurry, repeat steps A to E multiple times to obtain the water retention of different thickened slurries in the process of preventing and controlling coal spontaneous combustion in various stages of coal spontaneous combustion in the current goaf.

9. The working method of the device for testing the water retention and cooling performance of thickened slurry according to claim 8, characterized in that: The temperature set in the low-temperature oxidation stage is 40°C±1°C, the temperature set in the self-heating stage is 65°C±1°C, and the temperature set in the self-ignition stage is 85°C±1°C.

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