Optimal selection method and experimental system for pressure type atomizing nozzles for mining spraying and dust-settling equipment

Abstract

The invention relates to a pressure type atomizing nozzle optimal selection method for mining spraying and dust falling equipment and an experiment system, and belongs to the field of coal mine high-pressure spraying and dust falling. The experiment system comprises a simulation roadway, an axial flow fan, a wind speed sensor, a spraying device, a water container and a phase Doppler particle dynamic analyzer, and the spraying device comprises a nozzle and a spraying device body detachably connected with the nozzle. The positions of the nozzle and the water container are determined according to the distance L between the on-site nozzle and the dust source and the atomization angle of the nozzle under the working conditions of no wind and on-site maximum spraying pressure, so that the water container only collects the effective spraying amount of the nozzle. The optimal selection method for the nozzles comprises the steps of collecting field parameters, simulating corresponding working conditions in an experimental system, and screening the nozzles according to the step-by-step flow of range screening, effective water quantity screening, fog drop speed screening and particle size matching screening, so that the screened nozzles can be accurately matched with the actual working conditions in a well, and the spraying and dust falling effects are improved.

Description

Technical Field

[0001] This invention belongs to the field of high-pressure spray dust suppression in coal mines, and relates to a method and experimental system for the selection of pressure atomizing nozzles for mining spray dust suppression equipment. Background Technology

[0002] Dust is generated during coal mining operations. With the continuous improvement of mechanization in the coal industry, the severity of dust hazards has significantly increased, leading to a continuous rise in the number of patients with pneumoconiosis. To achieve efficient dust control at mining faces, scholars both domestically and internationally have conducted extensive research, proposing technologies such as coal seam water injection, spray dust suppression, ventilation dust removal, and dust collectors. Among these, spray dust suppression technology has become the most widely used dust control technology in coal mines due to its advantages of convenient operation, simple installation, and low cost. Coal mines are primarily underground, and the water spraying points at the underground mining faces are located hundreds of meters underground. Due to the weight of the water, the water in the supply pipelines can naturally form a certain pressure, providing the basic conditions for the application of spray dust suppression technology.

[0003] Nozzle selection is a crucial step in improving the dust suppression efficiency of spray dust control equipment. However, current nozzle selection is largely based on atomization parameters derived from tests conducted in windless environments. In contrast, dust-generating areas such as underground coal mine working faces are actually under windy conditions. This discrepancy between the test environment and actual working conditions leads to suboptimal dust suppression efficiency from the selected nozzles. To address the issue of inaccurate atomization parameter measurements and insufficient adaptability of commonly used pressure atomizing nozzles in coal mines, resulting in lower-than-expected dust suppression efficiency, it is necessary to develop a method and experimental system for selecting pressure atomizing nozzles for mining spray dust control equipment. This will allow for precise matching to actual underground working conditions and improve the dust suppression effect. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method and experimental system for selecting pressure atomizing nozzles for mining spray dust suppression equipment, so as to achieve precise matching between the nozzles and the dust suppression scenario and improve the spray dust suppression effect.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An experimental system for a pressure-type atomizing nozzle in a mine dust suppression spray device includes a simulated roadway with an air inlet and an air outlet at both ends. Along its length, the simulated roadway includes a rectifying section, an experimental section, and a fan section arranged sequentially. The fan section is equipped with an axial flow fan to achieve negative pressure ventilation in the simulated roadway, with the axis of the axial flow fan coinciding with the vertical central axis of the simulated roadway. The experimental section is equipped with a wind speed sensor and a spray device. The wind speed sensor is positioned corresponding to the axis of the axial flow fan, and the spray device includes a nozzle installed within the experimental section and a spray nozzle detachably connected to the nozzle. The main body of the misting device has its nozzle's center aligned with the vertical central axis of the simulated tunnel. A pressure gauge is installed on the high-pressure water pipe connecting the nozzle and the main body of the misting device to monitor the spray pressure in real time. Below the nozzle is a water-holding container that can move along the length of the simulated tunnel. The water-holding container includes a support base, a circular-opening water-holding container body mounted on the support base, and a drain pipe connected to the water-holding container body. The drain pipe is equipped with a drain valve. The circular edge of the water-holding container body away from the air inlet is aligned with a circle centered on the projection of the nozzle onto the water-holding container body, with an L*tan... i The nozzle is tangent to a circle with radius 2, and L is the distance between the nozzle and the dust source. i 2 represents the atomization angle of the nozzle under no wind and maximum spray pressure conditions. The distance L between the water container and the nozzle in the vertical direction is L. A phase Doppler particle dynamic analyzer is installed on the outside of the test section to achieve accurate testing of droplet size.

[0007] Optionally, the interior of the water container is provided with an absorbent layer.

[0008] Optionally, the water container body is an inverted "barn shape", including a cylindrical section and a conical section arranged vertically, with an absorbent layer covering the inner wall of the conical section and / or the lower half of the inner wall of the cylindrical section.

[0009] Optionally, the absorbent layer is a sponge.

[0010] Optionally, the water container is set on a single or double guide rail arranged along the length of the simulated tunnel.

[0011] Optionally, the support base of the water container has a roller structure that matches the guide rail.

[0012] Optionally, the nozzle mounting height is adjustable to match different sizes of L.

[0013] Optionally, the nozzle can be detachably installed at one end of a U-shaped high-pressure rigid water pipe, and the other end of the high-pressure rigid water pipe is fixed on the water pipe mounting base. The water pipe mounting base has a pre-set through hole inside. One end of the through hole near the high-pressure rigid water pipe is connected to the high-pressure rigid water pipe, and the other end is connected to the spray device body through a high-pressure soft water pipe. The water pipe mounting base (23) has two rows of vertically arranged through holes to be adapted to the pre-set bolts set on the simulated tunnel column to realize the graded adjustment of the nozzle installation height.

[0014] Optionally, the spraying device body includes a spray pump, which is connected to a water tank.

[0015] Optionally, the simulated tunnel has a net height of 3500mm, a net width of 2000mm, a length of 20000mm, a rectification section length of 5m, an experimental section length of 5m, and a fan section length of 10m.

[0016] Optionally, the wind speed sensor is located 6m away from the air inlet of the simulated roadway and at the axis position of the axial flow fan. The wind speed sensor is a mining bidirectional wind speed sensor.

[0017] A preferred method for a pressure-type atomizing nozzle used in a mining dust suppression spray system, based on the above-mentioned experimental system, includes the following steps: S1. On-site parameter acquisition: Multiple measurements of the on-site airflow velocity at the actual application location of the nozzle during field operations are performed, and the maximum value from the measurement results is recorded. V `max` represents the simulated airflow velocity in the roadway within the experimental system. Dust samples were collected from the work site during normal operation, and particle size analysis was performed to determine the dust particle size distribution range at the dust-generating point. When the cumulative dust mass percentage reached 80%, the corresponding dust particle size value was set as `a` μm. The distance `L` between the nozzle of the proposed spray dust suppression equipment and the dust source point was measured. The maximum spray pressure that the proposed spray dust suppression equipment could provide during continuous and stable operation was investigated. P max; S2. Simulation Setup: Adjust the frequency switch of the axial flow fan to stabilize the simulated tunnel air velocity. V max, record the inverter frequency δ of the corresponding axial flow fan, and ensure stable operation for more than 5 minutes, ensuring that the wind speed change is less than 0.5%; S3. Range Screening: S3.1 Turn off the axial flow fan, install the candidate nozzle on the spray device body, and adjust the distance between the nozzle and the water container to L; S3.2 Repeat step S2, under pressure P max, wind speed VVerify the spray range under the maximum condition by observing whether the spray can reach the water container. If the spray cannot reach the container, replace it with the next candidate nozzle. If the spray can reach the container, the nozzle meets the range requirement. Measure the wind speed. V Atomization angle under maximum operating conditions i 1. Then turn off the axial flow fan and measure the atomization angle under no-wind conditions. i 2; S3.3 Repeat steps S3.1 to S3.2 until all candidate nozzles have been tested. The nozzles that meet the range requirements are selected as the preferred nozzle group one. S4. Effective water volume screening: Determine the flow rate a / 2 L / min of the preferred nozzle group in a windless state and the wind speed in a windy state. V For the flow rate b / 2 L / min under the maximum condition, nozzles with b / a≥0.8 are selected as the preferred nozzle group two; S5. Droplet Parameter Detection: Install the nozzles of the preferred nozzle group two onto the spray device body. Under spray pressures of Pmax / 4, Pmax / 2, 3Pmax / 4, and Pmax, use a phase Doppler particle dynamic analyzer to detect the characteristic particle size at the centerline of the mist flow at a distance L from the nozzle outlet. D 0.1 , D 0.5 , D 0.9 and maximum axial velocity; S6. Droplet velocity screening: Nozzles with a maximum axial velocity in the range of 20~30m / s are selected as the preferred nozzle group three; S7. Particle size matching screening: The nozzles whose droplet characteristic particle size meets the following conditions (1) to (3) are selected as suitable nozzles: (1) D 0.1 The particle size is controlled within (18, 22) μm. If the proportion of dust particles smaller than 7 μm exceeds 10%, the lower limit is taken, otherwise the upper limit is taken. (2) D0.5 is controlled at (90% (a+20) / 2, 110% (a+20) / 2) μm; (3) D0.9 is controlled at (90%(a+20), 110%(a+20)) μm; The corresponding spray pressure is the optimal spray pressure.

[0018] Optionally, in step S3, the fogging angle is obtained by taking a panoramic photo of the fog flow using a high-speed camera with its lens parallel to the simulated tunnel wall, and then importing the photo into CAD software for measurement.

[0019] Optionally, before the effective water volume test in step S4, an absorbent layer is laid in the water container to prevent water droplets from splashing, and the absorbent layer in the water container is sprayed until it is saturated with water before the drain valve of the water container is closed.

[0020] Optionally, before the effective water volume test in step S4, open the drain valve of the water container and spray water into the water-absorbing layer inside the water container. When a continuous flow of water is observed from the drain valve, stop spraying water and continue to keep the drain valve of the water container open until no water flows out, at which point the water-absorbing layer reaches a water-saturated state, and then close the drain valve of the water container.

[0021] The beneficial effects of this invention are as follows: 1. The present invention evaluates the spray atomization effect using atomization angle, range, effective water volume, and characteristic particle size (…). D 0.1 , D 0.5 , D 0.9 Five evaluation indicators, combining droplet velocity and other parameters, were used to assess the nozzle atomization effect from different perspectives. A nozzle atomization index testing experimental system was also constructed to simulate actual dust suppression scenarios, enabling the selected nozzles to accurately match actual underground working conditions and improve the spray dust suppression effect.

[0022] 2. The positional relationship between the nozzle and the water container of the present invention reproduces the positional relationship between the nozzle and the dust source on site. By controlling the position of the nozzle relative to the water container, the water container collects only the effective spray volume of the nozzle, which is equivalent to the effective spray volume of the nozzle acting on the dust source on site, thereby improving the accuracy of nozzle screening.

[0023] 3. By setting an absorbent layer inside the water container, the present invention can effectively prevent water droplet splashing, improve the accuracy of effective water collection, and further improve the accuracy of nozzle screening.

[0024] 4. By making the nozzle height adjustable, this invention can match different sizes of L (the distance between the nozzle and the dust source), enabling the experimental system to meet the screening of nozzles with different ranges required on site.

[0025] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 A schematic diagram of the experimental system for the optimal selection of pressure atomizing nozzles for mining spray dust suppression equipment; Figure 2 This is a schematic diagram of the structure of the spray frame and water container; Figure 3 This is a schematic diagram of the structure formed by laser-cut slits.

[0027] Reference numerals: 1. Rectifying section; 2. Wind speed sensor; 3. Water container; 31. Water container body; 32. Support base; 33. Drain pipe; 4. Spraying device; 21. Nozzle; 22. High-pressure rigid water pipe; 23. Water pipe mounting base; 24. First high-pressure flexible water pipe; 5. Simulated tunnel; 6. Axial flow fan; 7. Water tank; 8. Spray pump; 9. Second high-pressure flexible water pipe; 10. Fan frequency modulation switch; 12. Phase Doppler particle dynamic analyzer; 13. Coordinate frame; 14. Transparent acrylic plate; 15. Slide gate-type rear plate; 16. Slide gate-type front plate; 17. Wing screw; 18. Slot. Detailed Implementation

[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0029] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0030] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0031] Nozzle selection is a core element in improving spray dust suppression efficiency, and the key lies in the scientific and reasonable evaluation of nozzle atomization performance. From the perspective of spray dust suppression, current methods mainly employ three conventional nozzle performance indicators—atomization angle, range, and flow rate—along with a combination of characteristic diameter and statistical diameter to determine atomization quality. Droplet size evaluation methods are mainly divided into two categories: statistical average diameter and characteristic diameter. Commonly used characteristic diameters include... D 0.1 , D 0.5 , D 0.9 These represent the percentages of particles smaller than this diameter, which are 10%, 50%, and 90% of the total particle volume, respectively. A commonly used statistical average diameter... D 32 Its meaning is as follows: (1) In the formula: Indicates the first Particle size of seed type Indicates particle size as The number of droplets.

[0032] The present invention evaluates the spray atomization effect using atomization angle, range, effective water volume, and characteristic particle size. D 0.1 , D 0.5 , D 0.9 Five evaluation indicators, combining droplet velocity and other parameters, are used to assess the nozzle atomization effect from different perspectives. To achieve accurate measurement of these five indicators under simulated actual working conditions, a nozzle atomization indicator testing system is established to screen nozzles that can accurately match actual downhole working conditions and improve the dust suppression effect of spraying.

[0033] Please see Figure 1~Figure 3This is an experimental system for the optimal selection of pressure-type atomizing nozzles for a mine dust suppression spray device. The figure shows the following structure: rectifier section 1, wind speed sensor 2, water container 3, water container body 31, support base 32, drain pipe 33, spray device 4, nozzle 21, high-pressure rigid water pipe 22, water pipe mounting base 23, first high-pressure flexible water pipe 24, simulated roadway 5, axial flow fan 6, water tank 7, spray pump 8, second high-pressure flexible water pipe 9, fan frequency control switch 10, phase Doppler particle dynamic analyzer 12, coordinate frame 13, transparent acrylic plate 14, chute gate-type rear plate 15, chute gate-type front plate 16, wing screw 17, slot 18. The experimental system mainly consists of simulated roadway 5, axial flow fan 6, wind speed sensor 2, spray device 4, water container 3, and phase Doppler particle dynamic analyzer 12.

[0034] The simulated roadway 5 is rectangular and can be constructed from foam sandwich panels. It has a net height of 3500mm, a net width of 2000mm, and a length of 20000mm. Along its length, it is divided into three functional sections: a rectification section 1 (5m long), an experimental section (5m long), and a fan section (10m long). The left side of the simulated roadway 5 is the air inlet, and the right side is the air outlet. The fan axis coincides with the vertical central axis of the simulated roadway. The space outside the air outlet can be sealed with foam sandwich panels. According to the "Coal Mine Safety Regulations," the permissible air velocity in coal mining faces, coal roadways during excavation, and semi-coal-rock roadways is 0.25m / s to 4m / s, and the permissible air velocity in rock roadways during excavation is 0.15m / s to 4m / s. Therefore, the maximum designed air velocity for the experiment is 4m / s, requiring an air volume of 100800m³ / h. Because the roadway length is relatively short, the effect of wind resistance is not considered. The outlet fan was selected as an XZY-14A axial flow fan with a rated air volume of 110,000 m³ / h, which met the test requirements. To more closely resemble the actual field conditions, negative pressure ventilation was adopted. During the test, the air volume was adjusted using a frequency converter. Based on the relationship between frequency, rotational speed, air volume, cross-section, and wind speed, the relationship between frequency and simulated roadway wind speed was obtained, as shown in Table 1.

[0035] Table 1. Relationship between simulated tunnel wind speed and frequency

[0036] After setting the frequency, a GFY15(B) type mine bidirectional wind speed sensor located at 6m from the air inlet of simulated roadway 5 and at the center point of the roadway cross section was used for comparison and calibration. After actual measurement, the actual wind speed matched the calculated wind speed.

[0037] The main function of the water container 3 is to measure the effective water volume of the nozzle 21 of the spray device 4. It includes a support base 32, a water container body 31 with a circular opening mounted on the support base 32, and a drain pipe 33 connected to the water container body 31. The water container body 31 can be made of Q235 steel plate, with an inverted "barn" shape, i.e., a cylindrical section at the top and a conical section at the bottom. The diameter of the bottom surface of the conical section is the same as that of the cylindrical section, both being 1800mm. The conical section is 100mm high, with the tip pointing downwards and 100mm from the ground. An L-shaped drain pipe 33 with an inner diameter of 30mm is installed at the center of the conical tip, and a drain valve is installed at the end of the drain pipe 33. The cylindrical section is 100mm high. The interior of the water container 3 (both the cylindrical and conical sections) is covered with a sponge of the same shape as the container. The cylindrical section of the sponge is 50mm high, and the conical section is 100mm high, perfectly matching the height of the corresponding sections of the container. The main function of the sponge is to slow down the high-speed mist generated by the nozzle 21 and prevent water droplets from splashing. Two parallel guide rails, each 5m long, are arranged along the length of the simulated tunnel 5. The guide rails are centered on the cross-section where the water pipe mounting base 23 is located. The water container 3 is mounted on the guide rails through the support base 32 arranged on the cone and can move along the guide rails.

[0038] The spraying device 4 includes a nozzle 21, a spray frame, connecting pipes, and a spray pump 8, all located within the test section. The spray pump 8 is connected to a water tank 7. The spray frame, used to mount the nozzle 41, includes a high-pressure rigid water pipe 22 and a water pipe mounting base 23 for fixing the high-pressure rigid water pipe 22. The connecting pipes include a first high-pressure flexible water pipe 24 and a second high-pressure flexible water pipe 9. The experimental nozzle 21 is detachably mounted on a circular nozzle seat at the end of the high-pressure rigid water pipe 22, and the center of the nozzle must precisely coincide with the vertical central axis of the simulated tunnel 5. The high-pressure rigid water pipe 22 is an inverted, wide-mouth U-shape and can be made of galvanized steel. The end of the high-pressure rigid water pipe 22 is fixedly connected to a square water pipe mounting base 23. The mounting base 23 has two rows of vertical through holes, three in each row, with uniform spacing. Two rows of vertically arranged bolts are pre-installed on the columns of the simulated tunnel 5. These columns can be steel columns, and the vertical spacing of the bolts perfectly matches the vertical spacing of the through holes in the water pipe mounting base 23. The water pipe mounting base 23 is fastened to the steel column by bolts passing through the through holes. By selecting bolts of different heights on the steel column to match the through holes in the water pipe mounting base 23, the installation height of the nozzle 21 can be adjusted in stages, achieving spray height adjustment. The bottom surface of the water pipe mounting base 23 has a KJ13 type quick-connect port. A through-hole is pre-installed inside the water pipe mounting base 23, one end of which is connected to the high-pressure rigid water pipe 22, and the other end is sealed to the quick-connect port. A quick-connect connector is used to connect a 3m long first high-pressure flexible water hose 24, which is a high-pressure rubber hose. The other end of the first high-pressure flexible water hose 24 is connected to a tee connector. One end of the tee connector is equipped with a pressure gauge with a range of 0~10MPa and an accuracy of 0.1MPa for real-time monitoring of the spray pressure. The other end is connected to the spray pump 8 via a second high-pressure hose 9, which is also a high-pressure rubber hose. The spray pump 8 has a rated operating pressure of 16MPa and a nominal flow rate of 250L / min, which meets the high-pressure water supply requirements of the experiment.

[0039] The phase Doppler particle dynamic analyzer 12 includes a main unit, a laser emitter, a laser receiver, and a coordinate frame 13. These components work together to achieve precise measurement of droplet size. The coordinate frame 13 is used to precisely adjust the spatial position of the laser emitter and receiver, ensuring accurate alignment of the laser with the test point. The laser emitter has a rated power of 5W and emits a green laser beam directionally towards the droplet flow at the test point. After reflection from the droplets, the laser beam is captured by the laser receiver. The captured laser signal is transmitted to the main unit of the phase Doppler particle dynamic analyzer, where dedicated testing software analyzes the data to ultimately obtain the particle size data of the droplet flow at the test point. The core technical parameters of this phase Doppler particle dynamic analyzer are as follows: particle size measurement range of 0.5–2000 μm, and particle size measurement accuracy of 0.5%, which meets the high-precision droplet size detection requirements of this experiment.

[0040] To reduce the impact of the simulated tunnel wall on the laser, the simulated tunnel wall within the coordinate frame 13 is based on multiple strip-shaped transparent acrylic sheets 14. These transparent acrylic sheets 14 are inserted above a sliding gate-shaped rear plate 15 set on the simulated tunnel wall and fall along a chute formed by the sliding gate-shaped rear plate 15 and the sliding gate-shaped front plate 16. A slit 18 is provided at the laser transmission position, formed by the gap between two adjacent transparent acrylic sheets. The transparent acrylic sheet at the upper position of the slit 18 is tightened and fixed to the sliding gate-shaped front plate 16 by a wing screw 17 threaded onto the sliding gate-shaped rear plate 15. The transparent acrylic sheets 14 are stacked sequentially until they exceed the sliding gate-shaped rear plate 15. The distance between the sliding gate-shaped rear plate 15 and the sliding gate-shaped front plate 16 is slightly greater than the thickness of the transparent acrylic sheet 14 to facilitate its descent. The transparent acrylic sheet 14 can be manufactured in various specifications with different heights according to actual needs, so as to form slits 18 at different height positions. The slits 18 enable the laser to accurately reach the test mist point from the slits 18 formed by the gaps between the sheets, thus improving the accuracy of the test.

[0041] The nozzle is mainly tested for atomization angle, effective water volume, range, droplet size, and droplet velocity. The testing process is as follows: Step 1: Use an anemometer to measure the airflow velocity at the actual application location of the nozzle multiple times, and take the maximum value from the measurement results. V `max` is used to simulate the airflow velocity in the tunnel. A CCZ20 respirable dust sampler was used to sample dust at the work site during normal operation, according to the "GB / Z 159 Sampling Specification for Monitoring Hazardous Substances in Workplace Air" (the sampler was required to be as close as possible to the dust source). A dust particle size analyzer was used to analyze the particle size distribution of the collected dust, determining the particle size distribution range at the dust generation point. The data was analyzed, and when the cumulative mass percentage of dust particles reached 80%, the corresponding dust particle size value was set as `a` μm. The distance `L` between the nozzle of the proposed spray dust suppression equipment and the dust source was measured using a measuring tape. The maximum spray pressure that the spray dust suppression equipment could provide during continuous and stable operation was investigated. P max.

[0042] Step 2: Turn on the start switch of the axial flow fan, slowly adjust the frequency converter of the axial flow fan, and observe the value of the GFY15(B) type mining bidirectional wind speed sensor. Wait until the value measured by the wind speed sensor matches the maximum value of the anemometer. V When the maximum value is consistent, stop the frequency converter adjustment and run it stably for more than 5 minutes. If the value of the wind speed sensor changes during the operation, the frequency converter needs to be fine-tuned. When the continuous change of the wind speed sensor value is less than 0.5%, record the frequency δ of the frequency converter at this time.

[0043] Step 3: Install the candidate nozzle onto the nozzle mounting base, and adjust the distance from the nozzle outlet to the water container to L. Start the axial flow fan, slowly adjust the frequency converter to frequency δ, and then slowly adjust the spray pump pressure to... P Max out the spray pattern and observe whether the mist can reach the water container. If the mist cannot reach the container, replace it with the next candidate nozzle. If the nozzle range is suitable, use a high-speed camera with the lens parallel to the tunnel wall to take multiple panoramic photos of the mist flow. Import the photos into CAD software to measure the angle and obtain the actual atomization angle of the nozzle under windy conditions. i 1. Turn off the axial flow fan, and again use a high-speed camera with the lens parallel to the tunnel wall to take multiple panoramic photos of the mist flow. Import the photos into CAD software to measure the angle and obtain the atomization angle of the nozzle under windless conditions. i 2 。 Repeat the above testing steps until all candidate nozzles have been tested. Then, select the set of nozzles that meet the range requirements of the spray dust suppression equipment and name it Preferred Nozzle Group 1.

[0044] Step 4: Conduct an effective water volume test on the optimized nozzle group. The effective water volume of the nozzle should not be less than 80% of the nozzle spray volume under windless conditions. The specific operation is as follows: Adjust the position of the water container so that the edge of the water container furthest from the air inlet is aligned with the vertical projection of the nozzle onto the water container, using L*tan... i Tangent to a circle with a radius of 2. Open the water tap on the water supply line and spray tap water evenly onto the surface of the absorbent sponge through the hose connected to the tap. At the same time, open the drain valve of the water container. When a continuous flow of water is observed from the drain valve, close the water tap, but keep the drain valve open until no water flows out. At this point, the absorbent sponge is fully saturated with water. Turn on the spray pump and quickly adjust it to... P After 2 minutes, turn off the spray pump. Open the outlet valve of the water container and pour the flowing water into the bucket. When no more water flows out, close the drain valve of the water container. Weigh the bucket using an electronic scale to obtain the weight a kg. The flow rate of the nozzle in the windless state is a / 2 L / min. Turn on the axial flow fan and adjust the frequency to δ. After the wind speed stabilizes, measure the flow rate of the nozzle in the windy state. The test process is the same as above. The flow rate of the nozzle in the windy state is b / 2 L / min. If the value of b / a is less than 0.8, it does not meet the requirements. Repeat the above test steps. After all the nozzles in the first group of preferred nozzles have been tested, the set of nozzles that meet the effective water volume requirements can be selected and named the second group of preferred nozzles.

[0045] Step 5: Measure droplet size using a phase Doppler particle dynamic analyzer. Turn on the axial flow fan and adjust the frequency to δ. After the wind speed stabilizes, measure the droplet size of each nozzle in the preferred nozzle group two under windy conditions. Select the test point as the position L at the distance from the nozzle outlet along the central axis of the nozzle mist flow field. Install the nozzles of the preferred nozzle group two sequentially on the nozzle mounting base, adjust the nozzle height and coordinate frame so that the laser emitter can emit laser light through the slit into the mist flow at the test point, start the spray pump, and adjust the spray pressure to... P max / 4 MPa P max / 2 MPa, 3 P max / 4 MPa P At maxMPa, the phase Doppler particle dynamic analyzer was activated to analyze and obtain the characteristic particle size of each nozzle in the preferred nozzle group two under different spray pressures. D 0.1 , D 0.5 , D 0.9 The data was collected, and the maximum axial velocity at each nozzle test point was tested.

[0046] Step 6: Application of Maximum Axial Velocity of Droplets. Based on relevant literature, theoretical and experimental research in the field of spray dust suppression, it is known that the dust collection effect is optimal when the droplet velocity is in the range of 20-30 m / s. A comparative analysis was conducted on the droplet velocity data of each nozzle in the second group of preferred nozzles under different spray pressures. Nozzles whose droplet velocities meet the above-mentioned optimal range were selected and named the third group of preferred nozzles.

[0047] Step 7: Comparison of dust particle size and droplet size. Based on theoretical and experimental research in the field of spray dust suppression, the closer the particle size of the droplets and dust particles are, the higher the collision and collection efficiency; however, the smaller the droplet size, the faster its evaporation rate. Taking into account both factors, and combined with the requirement for the collection and settling of respirable dust that poses a significant threat to human health, the lower limit of the droplet size is set at 20 μm, and the upper limit of the droplet size is set at (a+20) μm.

[0048] The selection criteria for droplet size under different pressures for each of the three nozzles in the preferred nozzle group are as follows: ①Characteristic droplet size of each nozzle D 0.1 The particle size should be controlled at around 20μm; if the proportion of dust particles smaller than 7μm in the dustfall area exceeds 10%, priority should be given to selecting [specific particle size range]. D 0.1 A nozzle slightly smaller than 20 μm; ②Characteristic droplet size of each nozzle D 0.9 It needs to be controlled at around (a+20) μm.

[0049] ③Characteristic droplet size of each nozzle D 0.5 It needs to be controlled at around (a+20) / 2 μm.

[0050] Based on the above comparison, nozzles that meet the above standard requirements can be identified as suitable nozzles for spray dust suppression equipment, and the corresponding spray pressure is the optimal spray pressure of the equipment in the target dust suppression scenario.

[0051] This invention constructs a nozzle atomization index testing experimental system that can simulate actual dust suppression scenarios. It can accurately simulate the permissible wind speed range of 0.15m / s to 4m / s on-site, and achieve precise wind speed control through the correspondence between frequency, rotation speed, air volume, cross-section, and wind speed. This experimental system can accurately measure atomization angle, range, effective water volume, droplet size, and velocity. The structural design, arrangement, and functional adaptation of each component form a unified experimental system architecture.

[0052] This invention establishes a multi-dimensional, step-by-step nozzle optimization method. First, on-site parameters are collected (measured maximum wind speed Vmax, dust particle size distribution, nozzle-to-dust source distance L, and maximum spray pressure Pmax in the target scenario). Then, corresponding working conditions are simulated in an experimental system, and the selection process proceeds in a step-by-step manner: "range screening → effective water volume screening → droplet velocity screening → particle size matching screening." The optimal nozzle group one is obtained through atomization angle testing and range verification under windy / no-wind conditions; the optimal nozzle group two is obtained by ensuring the effective water volume is not less than 80% of the nozzle flow rate under no-wind conditions; and the optimal nozzle group three is obtained by ensuring the maximum axial velocity of the droplets is in the range of 20-30 m / s. Finally, the droplet size standard is determined based on the dust particle size distribution. D 0.1 Approximately 20μm D 0.5 Approximately (a+20) / 2μm D 0.9 Approximately (a+20) μm, where a is the dust particle size accounting for 80% of the total mass, to select suitable nozzles and corresponding optimal spray pressures.

[0053] This invention effectively solves the core problem of the disconnect between traditional nozzle selection and actual underground working conditions, achieving significant technical results. By constructing a simulated roadway system that conforms to the "Coal Mine Safety Regulations," it accurately reproduces the allowable underground wind speed of 0.15 m / s to 4 m / s, completely overcoming the drawbacks of atomization parameter distortion caused by testing in windless environments. It innovatively employs five evaluation indicators, combined with specialized equipment such as a phase Doppler particle dynamic analyzer, to achieve precise measurement of parameters such as atomization angle and droplet size. Through a step-by-step screening process of "range → effective water volume → droplet velocity → particle size matching," the selected suitable nozzle has a droplet velocity that matches the optimal collection range of 20-30 m / s, and its particle size is precisely matched with the dust particle size of the target dustfall area, significantly improving collection efficiency. The system structure is compliant and practical, adaptable to different mining scenarios, providing a scientific standard for nozzle selection, effectively reducing underground dust concentration, reducing the risk of pneumoconiosis, and providing strong protection for coal mine safety production and the health of workers.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An experimental system for the optimal selection of pressure atomizing nozzles for mining spray dust suppression equipment, characterized in that: The simulated tunnel (5) includes an air inlet and an air outlet at both ends. Along its length, the simulated tunnel (5) includes a rectification section (1), an experimental section, and a fan section arranged in sequence. The fan section is equipped with an axial flow fan (6) to achieve negative pressure ventilation in the simulated tunnel (5). The axis of the axial flow fan (6) coincides with the vertical central axis of the simulated tunnel (5). The experimental section is equipped with a wind speed sensor (2) and a spray device (4). The wind speed sensor (2) is set at the position corresponding to the axis of the axial flow fan (6). The spray device (4) includes a nozzle (21) set in the experimental section and a spray device body detachably connected to the nozzle (21). The center of the nozzle (21) is aligned with the simulated tunnel. The vertical central axis of the tunnel (5) coincides with the high-pressure water pipe connecting the nozzle and the spray device body, and a pressure gauge is provided on it to monitor the spray pressure in real time. Below the nozzle (21) is a water container (3) that can move along the length of the simulated tunnel (5). The water container (3) includes a support base (32), a water container body (31) with a circular opening set on the support base (32), and a drain pipe (33) connected to the water container body (31). A drain valve is provided on the drain pipe (33). The circular edge of the water container body (31) away from the air inlet is aligned with the projection of the nozzle (21) on the water container body (31) as the center and L*tan θ The nozzle is tangent to a circle with radius 2, and L is the distance between the nozzle and the dust source. θ 2 is the atomization angle of the nozzle under the condition of no wind and maximum spray pressure on site. The distance between the water container body (31) and the nozzle (21) in the vertical direction is L. A phase Doppler particle dynamic analyzer (12) is provided on the outside of the test section to achieve accurate testing of droplet size.

2. The experimental system for the preferred pressure atomizing nozzle of the mining spray dust suppression equipment according to claim 1, characterized in that: The interior of the water container body (31) is equipped with an absorbent layer.

3. The preferred experimental system for pressure atomizing nozzles in mining spray dust suppression equipment according to claim 2, characterized in that: The water container body (31) is in the shape of an inverted "barn", including a cylindrical section and a conical section arranged vertically, with an absorbent layer covering the inner wall of the conical section and / or the lower half of the inner wall of the cylindrical section.

4. The experimental system for the preferred pressure atomizing nozzle of the mining spray dust suppression equipment according to claim 1, characterized in that: The water container (3) is set on a single or double guide rail arranged along the length of the simulated tunnel.

5. The preferred experimental system for pressure atomizing nozzles in mining spray dust suppression equipment according to claim 4, characterized in that: The support base (32) of the water container (3) has a roller structure that matches the guide rail.

6. The experimental system for the preferred pressure atomizing nozzle of the mining spray dust suppression equipment according to claim 1, characterized in that: The installation height of the nozzle (21) is adjustable to match different sizes of L.

7. The experimental system for the preferred pressure atomizing nozzle of the mining spray dust suppression equipment according to claim 1, characterized in that: The nozzle (21) is detachably installed at one end of the inverted U-shaped high-pressure rigid water pipe (22). The other end of the high-pressure rigid water pipe (22) is fixed on the water pipe mounting base (23). The water pipe mounting base (23) has a pre-set through hole inside. One end of the through hole near the high-pressure rigid water pipe (22) is connected to the high-pressure rigid water pipe (22), and the other end is connected to the spray device body through the high-pressure soft water pipe. The water pipe mounting base (23) has two rows of vertically arranged through holes to match the pre-set bolts set on the simulated lane column to realize the graded adjustment of the nozzle installation height.

8. The experimental system for the preferred pressure atomizing nozzle of the mining spray dust suppression equipment according to claim 1, characterized in that: The spray device body includes a spray pump (8), and the spray pump (8) is connected to a water tank (7).

9. The preferred experimental system for pressure atomizing nozzles in mining spray dust suppression equipment according to claim 1, characterized in that: The simulated tunnel has a net height of 3500mm, a net width of 2000mm, a length of 20000mm, a rectification section length of 5m, an experimental section length of 5m, and a fan section length of 10m.

10. The experimental system for the preferred pressure atomizing nozzle of the mining spray dust suppression equipment according to claim 9, characterized in that: The wind speed sensor (2) is located 6m away from the air inlet of the simulated roadway and corresponds to the axis position of the axial flow fan (6). The wind speed sensor (2) is a mine bidirectional wind speed sensor.

11. A preferred method for a pressure atomizing nozzle used in a mining spray dust suppression device, characterized in that: A preferred experimental system for pressure atomizing nozzles in mining spray dust suppression equipment as described in any one of claims 1 to 10 is provided, comprising the following steps: S1. On-site parameter acquisition: Multiple measurements of the on-site airflow velocity at the actual application location of the nozzle during field operations are performed, and the maximum value from the measurement results is recorded. V `max` represents the simulated airflow velocity in the roadway within the experimental system. Dust samples were collected from the work site during normal operation, and particle size analysis was performed to determine the dust particle size distribution range at the dust-generating point. When the cumulative dust mass percentage reached 80%, the corresponding dust particle size value was set as `a` μm. The distance `L` between the nozzle of the proposed spray dust suppression equipment and the dust source point was measured. The maximum spray pressure that the proposed spray dust suppression equipment could provide during continuous and stable operation was investigated. P max; S2. Simulation Setup: Adjust the frequency switch of the axial flow fan to stabilize the simulated tunnel air velocity. V max, record the inverter frequency δ of the corresponding axial flow fan, and ensure stable operation for more than 5 minutes, ensuring that the wind speed change is less than 0.5%; S3. Range Screening: S3.1 Turn off the axial flow fan, install the candidate nozzle on the spray device body, and adjust the distance between the nozzle and the water container to L; S3.2 Repeat step S2, under pressure P max, wind speed V Verify the spray range under the maximum condition by observing whether the spray can reach the water container. If the spray cannot reach the container, replace it with the next candidate nozzle. If the spray can reach the container, the nozzle meets the range requirement. Measure the wind speed. V Atomization angle under maximum operating conditions θ 1. Then turn off the axial flow fan and measure the atomization angle under no-wind conditions. θ 2; S3.3 Repeat steps S3.1 to S3.2 until all candidate nozzles have been tested. The nozzles that meet the range requirements are selected as the preferred nozzle group one. S4. Effective water volume screening: Determine the flow rate a / 2 L / min of the preferred nozzle group in a windless state and the wind speed in a windy state. V For the flow rate b / 2 L / min under the maximum condition, nozzles with b / a≥0.8 are selected as the preferred nozzle group two; S5. Droplet Parameter Detection: Install the nozzles of the preferred nozzle group two onto the spray device body. Under spray pressures of Pmax / 4, Pmax / 2, 3Pmax / 4, and Pmax, use a phase Doppler particle dynamic analyzer to detect the characteristic particle size at the centerline of the mist flow at a distance L from the nozzle outlet. D 0.1 , D 0.5 , D 0.9 and maximum axial velocity; S6. Droplet velocity screening: Nozzles with a maximum axial velocity in the range of 20~30m / s are selected as the preferred nozzle group three; S7. Particle size matching screening: The nozzles whose droplet characteristic particle size meets the following conditions (1) to (3) are selected as suitable nozzles: (1) D 0.1 The particle size is controlled within (18, 22) μm. If the proportion of dust particles smaller than 7 μm exceeds 10%, the lower limit is taken, otherwise the upper limit is taken. (2) D 0.5 Controlled within (90% (a+20) / 2, 110% (a+20) / 2) μm; (3) D 0.9 Controlled within (90%(a+20), 110%(a+20)) μm; The corresponding spray pressure is the optimal spray pressure.

12. The preferred method for a pressure atomizing nozzle used in a mining spray dust suppression device according to claim 11, characterized in that: In step S3, the fogging angle is obtained by taking a panoramic photo of the fog flow using a high-speed camera with its lens parallel to the simulated tunnel wall, and then importing the photo into CAD software for measurement.

13. The preferred method for a pressure atomizing nozzle used in a mining spray dust suppression device according to claim 11, characterized in that: Before the effective water volume test in step S4, an absorbent layer is laid in the water container to prevent water droplets from splashing, and water is sprayed into the absorbent layer in the water container until it is saturated.

14. The preferred method for a pressure atomizing nozzle used in a mining spray dust suppression device according to claim 13, characterized in that: Before the effective water volume test in step S4, open the drain valve of the water container and spray water into the water-absorbing layer inside the water container. When a continuous flow of water is observed from the drain valve, stop spraying water and continue to keep the drain valve of the water container open until no water flows out, indicating that the water-absorbing layer has reached water saturation. Then close the drain valve of the water container.

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