Combined tunnel pre-dedusting equipment parameter optimization setting method and combined tunnel pre-dedusting equipment

Abstract

The invention relates to the field of tunnel dust removal, in particular to a parameter optimization setting method for combined tunnel pre-dust-removal equipment and the combined tunnel pre-dust-removal equipment. The parameter optimization setting method comprises the steps that S1, the inlet size and the barrel diameter are calculated based on the single-inlet air volume and the inlet air speed, and gas-phase and gas-solid two-phase flowing is simulated; parameters such as exhaust pipe insertion depth, cylinder height range and cone height are determined; s2-S3, by adjusting the ratio of the height of a cylinder cone to the diameter of a cylinder, the ratio of the diameter of an exhaust pipe to the diameter of the cylinder and the like, the optimal ratio with the least escape particles and the highest separation efficiency is selected; s4, comparing velocity fields, pressure fields and efficiencies of the cyclone dust collector and the combined equipment, and selecting optimal equipment; and S5, fixing size parameters, adjusting the connection angle of each stage, and selecting the optimal angle with the highest separation efficiency. On the basis of an equipment structure optimization principle, the high-efficiency combined tunnel pre-dedusting equipment suitable for tunnel dedusting is obtained through the parameter optimization setting method.

Description

Technical Field

[0001] This invention relates to the field of tunnel dust removal technology, specifically to a method for optimizing the parameters of a combined tunnel pre-dust removal device and the combined tunnel pre-dust removal device itself. Background Technology

[0002] Dust collectors, which are widely used in the industrial field, can be classified into mechanical dust collectors, bag dust collectors, electrostatic precipitators, and wet dust collectors according to their working principles. Each type of dust collector has a different structure and principle, and therefore is suitable for different workplaces.

[0003] Cyclone dust collectors, as the most widely used dust removal equipment, are simple in structure, inexpensive, occupy little space, have no moving parts, and are easy to clean. They are effective in removing dry dust in tunnels. However, a drawback of cyclone dust collectors is their low efficiency in removing fine dust. Therefore, many scholars at home and abroad have conducted systematic research on the structural parameters of various parts of the dust collector to address this deficiency, striving to achieve the goal of "high efficiency and low resistance." However, traditional single-stage cyclone dust collectors have a characteristic where the amount of air they can handle is positively correlated with the size of the floor space they occupy. As the volume increases, the diameter and height of the cyclone dust collector will also increase. Due to the limitation of the tunnel design height, the processing air volume of a single-stage cyclone will be affected. Although the combined multi-stage cyclone dust collection scheme has been mentioned in a few documents, the principle of combined multi-stage cyclone dust collection is relatively complex. The shape and size of each stage cylinder structure, the combination method, the processing capacity distribution, and the interaction of the flow field will all affect the processing effect and efficiency. Tunnel dust collection is a relatively special working condition. How to efficiently optimize the parameter design to obtain a combined multi-stage cyclone treatment structure suitable for tunnel dust collection is a major challenge we are currently facing. Summary of the Invention

[0004] To address the problems raised in the background art, the present invention provides a method for optimizing the parameters of a combined tunnel pre-dust removal device and a tunnel pre-dust removal device.

[0005] The technical solution of this invention is as follows: A method for optimizing the parameters of a combined tunnel pre-dust removal device includes the following steps: S1. Obtain the single-inlet processing air volume Q and gas inlet velocity V of the device, and calculate the inlet height a and width b, and cylinder diameter. D The gas phase flow field and gas-solid two-phase flow were simulated, and the insertion depth of the exhaust pipe was calculated based on the inlet height 'a'. S Based on the cylinder diameter D Obtain the height of the cylinder H a Value range, cone height H cExhaust pipe diameter D e ash discharge port diameter B ; S2. Keeping the entrance height a and width b constant, set different cone heights. H c With cylinder diameter D The optimal ratio relationship between the height of the cylinder cone and the diameter of the cylinder was selected by simulating the gas phase flow field and the gas-solid two-phase flow, and the ratio relationship with the minimum number of escaping particles and the highest separation efficiency was selected as the optimal ratio relationship between the height of the cylinder cone and the diameter of the cylinder. S3. With the inlet height a and width b remaining constant, different sizes of exhaust pipe diameter D are set. e The proportional relationship between the exhaust pipe diameter and the cylinder diameter D was used to simulate the gas phase flow field and the gas-solid two-phase flow. The proportional relationship with the highest separation efficiency was selected as the exhaust pipe diameter D. e Similarly, the optimal proportional relationship between the insertion depth S of the exhaust pipe and the inlet height a, and the optimal proportional relationship between the ash discharge port diameter B and the cylinder diameter D are obtained. S4. Compare the velocity field, pressure field, and separation efficiency of a cyclone dust collector and a combined tunnel pre-dust removal device to obtain the optimal device; S5. With the device size parameters and connection method unchanged, set the connection angle between different levels of cyclone dust collectors, and select the connection angle with the highest separation efficiency as the optimal connection angle.

[0006] The calculation of the inlet height a and width b, and the cylinder diameter mentioned in S1 D The specific method is as follows: , , , .

[0007] In S1, the exhaust pipe insertion depth is calculated based on the inlet height 'a'. S The specific method is as follows: .

[0008] Based on cylinder diameter D Obtain the height of the cylinder H a Value range, cone height H c Exhaust pipe diameter D e ash discharge port diameter B The specific method is as follows: , , , .

[0009] The gas phase flow field was simulated using the RSM model.

[0010] Gas-solid two-phase flow was simulated using the Euler-Lagrange coupling method.

[0011] Separation efficiency is obtained based on dust particle trajectory prediction, which is performed using a stochastic trajectory model.

[0012] The ratio of selecting the minimum number of escaped particles to the highest separation efficiency described in S2 is as follows: if the ratios corresponding to the minimum number of escaped particles and the highest separation efficiency are different, then the highest separation efficiency has a higher priority than the minimum number of escaped particles.

[0013] A combined tunnel pre-dust removal device includes a two-stage cyclone dust collector and multiple first-stage cyclone dust collectors connected thereto; The secondary cyclone dust collector includes a vertically arranged cylindrical body and a vertically arranged cone with a diameter that gradually decreases from top to bottom. The cone has a hollow interior. The top of the cylindrical body is closed and connected to a downward-opening air duct. The end of the air duct away from the top of the cylindrical body is connected to an exhaust fan. Multiple tangential air inlet channels with stepped heights are opened on the cylindrical body. The tangential air inlet channels are connected to the top of the primary cyclone dust collector through an exhaust pipe. The primary cyclone dust collector also includes a vertically arranged cylindrical body and a vertically arranged cone with a diameter that gradually decreases from top to bottom, as well as a primary dust-laden gas inlet channel that is tangentially connected to the cylindrical body. The dimensions of the cylinder and cone of the secondary cyclone dust collector are larger than those of the cylinder and cone of each primary cyclone dust collector.

[0014] Preferably, the maximum diameter at the top of the cone of both the secondary cyclone dust collector and the primary cyclone dust collector is the same as the diameter of the inner wall of the cylinder.

[0015] The beneficial effects of this invention are as follows: This invention designs a combined tunnel pre-dust removal equipment with a "2+1" structural model, consisting of two primary cyclone dust collectors and one secondary cyclone dust collector. The secondary cyclone dust collector has a larger diameter and a higher cone height, allowing for a longer residence time of the dust-laden gas. This significantly improves the dust removal efficiency for fine dust. Furthermore, the multi-stage series structure increases the volume of the dust removal equipment, which helps to increase the air volume it can handle, thus speeding up the time required for personnel and equipment to enter the site.

[0016] Under the constraints of tunnel height and cost, the parameter optimization setting method of the combined tunnel pre-dust removal equipment of the present invention can quickly determine important parameters such as the shape and size of each stage of the cylinder structure, the combination method, the processing capacity allocation, and the proportional relationship between the size of different parts and the cylinder diameter. This optimizes the gas flow field, improves the dust removal effect, and makes the dust removal efficiency of the tunnel pre-dust removal device higher. For example, the diameter design of the exhaust pipe can increase the separation efficiency of the equipment to 91.4%, and the combined series angle design can increase the dust removal efficiency of the equipment to 96.7%. Attached Figure Description

[0017] In the attached diagram: Figure 1 This is a schematic diagram of the overall structure of a combined tunnel pre-dust removal equipment.

[0018] The components represented by the various reference numerals in the diagram are: 1. Primary cyclone dust collector; 11. Primary dust-laden gas inlet channel; 12. Circular hole; 2. Secondary cyclone dust collector; 21. Cylinder; 22. Cone; 23. Air duct; 24. Exhaust pipe; 25. Tangential air inlet channel; 26. Exhaust fan. Detailed Implementation

[0019] Example 1: To meet the requirements of dust removal equipment under tunnel construction conditions and to enable the dust removal equipment to better cope with tunnel construction, tunnel pre-dust removal equipment must have multiple pollutant inlets, the ability to handle large air volumes, and a small footprint.

[0020] Based on the above analysis of the capabilities of tunnel pre-dust removal equipment and the research on conventional dust removal equipment, it was found that cyclone dust collectors have the advantages of simple manufacturing, no moving parts, large air volume handling capacity, and small footprint, making them very suitable for dust removal in tunnel construction. However, cyclone dust collectors have a characteristic: the air volume they can handle is positively correlated with the size of the footprint. That is, as the air volume handling capacity increases, the diameter and height of the cyclone dust collector also increase. Due to the limitations of the tunnel design height, the air volume handling capacity of a single-stage cyclone will be affected. Therefore, to make cyclone dust collectors adaptable to tunnel construction conditions, structural improvements and refinements are necessary.

[0021] Firstly, the combined tunnel pre-dust removal equipment is structurally optimized as follows: like Figure 1 As shown, the optimized combined tunnel pre-dust removal equipment in this embodiment includes a secondary cyclone dust collector 2 in the middle, and multiple primary cyclone dust collectors 1 connected thereto.

[0022] The secondary cyclone dust collector 2 includes a vertically arranged cylindrical body 21 and a vertically arranged cone 22 below it with a diameter that gradually decreases from top to bottom. The cone 22 has a hollow interior, and the diameter at its maximum at the top is the same as the inner wall diameter of the cylindrical body 21. The upper part of the cylindrical body 21 is closed and connected to a downward-opening U-shaped air duct 23. The end of the air duct 23 away from the upper part of the cylindrical body is connected to an exhaust fan 26. Multiple tangential air inlet channels 25 with stepped heights are opened on the cylindrical body 21. The tangential air inlet channels 25 are connected to the upper part of the primary cyclone dust collector 1 through an exhaust pipe 24. This tangential air inlet channel 25 is also the gas inlet of the secondary cyclone dust collector 2.

[0023] In this embodiment, the cross-sectional area of ​​the tangential intake channel 25 increases from the exhaust pipe 24 side to the cylinder 21 side.

[0024] The primary cyclone dust collector 1 also includes a vertically arranged cylindrical body and a vertically arranged cone with a diameter that gradually decreases from top to bottom, which has the same shape as the cylindrical body and cone of the secondary cyclone dust collector 2. The primary cyclone dust collector 1 also includes a primary dust-laden gas inlet channel 11 that is tangentially connected to its cylindrical body.

[0025] In this embodiment, the air inlet of the exhaust pipe 24 connected to the top of the cylinder of the first-stage cyclone dust collector 1 is a round hole 12, which is connected to the tangential air inlet channel 25 on the cylinder of the second-stage cyclone dust collector 2. The air inlet area of ​​the tangential air inlet channel 25 is larger than the air inlet area of ​​the round hole 12.

[0026] In this embodiment, the dimensions of the cylinder 21 and cone 22 of the secondary cyclone dust collector 2 are larger than the dimensions of the cylinder 21 and cone 22 of each primary cyclone dust collector 1. A primary cyclone dust collector 1 is connected to each side of the secondary cyclone dust collector 2, and a dust collection box is provided at the lower end of the cone 22 of both the primary cyclone dust collector 1 and the secondary cyclone dust collector 2.

[0027] Considering the limited space, high dust concentration, and wide particle size distribution in tunnel construction, a combined tunnel pre-dust removal equipment was designed with a "2+1" structural model, such as... Figure 1 As shown. Under the negative pressure condition of the exhaust fan 26, the dust-laden gas generated near the working face enters the dust removal equipment through the dual inlets of the primary cyclone dust collector 1. The dual inlets improve the efficiency of dust-laden gas intake. After purification by the primary cyclone dust collector 1, the coarse dust in the dust-laden gas is basically removed. The preliminarily cleaned gas enters the secondary cyclone dust collector 2 through the secondary dust-laden gas inlet. The secondary cyclone dust collector 2 has a larger diameter and a larger cone 22, allowing the dust-laden gas to have a longer residence time. This measure significantly improves the dust removal efficiency for fine dust. In addition, the multi-stage series structure increases the volume of the dust removal equipment, which helps to increase the processing air volume of the dust removal equipment and can speed up the arrival time of operators and equipment.

[0028] A method for optimizing the parameters of a combined tunnel pre-dust removal device includes the following steps: The combined tunnel pre-dust removal equipment has a simple structure, no moving parts, a small footprint, and is easy to operate and manage. There are specific proportional relationships between the parameters of each component; changes in these relationships will affect the overall dust removal performance.

[0029] The working principle of the combined tunnel pre-dust removal equipment is to use the centrifugal force generated by the rotation of the airflow to separate dust from the gas. The dust-laden airflow rotates downwards along the inlet direction of the tunnel pre-dust removal equipment. When the dust collides with the wall, the dust particles lose inertia and slide down the inner wall. This downward rotating airflow is called the outer vortex. When the outer vortex reaches the bottom of the cone 22, it turns upwards under the action of pressure, rotates upwards along the axis, and finally exits from the exhaust pipe 24. This upward airflow is called the inner vortex.

[0030] S1. Obtain the single inlet processing air volume Q and gas inlet velocity V of the equipment; calculate the inlet height a and width b, and the cylinder diameter D; simulate the gas phase flow field and gas-solid two-phase flow; calculate the exhaust pipe insertion depth S based on the inlet height a; and obtain the cylinder height H based on the cylinder diameter D. a Value range, cone height H c Exhaust pipe diameter D 24 e , ash discharge port diameter B.

[0031] The performance indicators for evaluating combined tunnel pre-dust removal equipment mainly include dust removal efficiency, pressure loss, and air volume handling capacity. Among these, dust removal efficiency and pressure loss have the greatest impact on the performance of combined tunnel pre-dust removal equipment. Generally speaking, a good combined tunnel pre-dust removal equipment should exhibit the characteristics of "high efficiency and low resistance." The structural dimensions of each part of the combined tunnel pre-dust removal equipment have a significant impact on performance indicators. Practice has shown that the greater the overall height of the combined tunnel pre-dust removal equipment, the higher the dust removal efficiency. Considering the height limitations imposed by installation space, the structural parameters of key components of the tunnel pre-dust removal equipment should be determined based on the air volume handling capacity.

[0032] First, calculate the relevant parameters of the primary cyclone dust collector 1, and then set the parameters of the secondary cyclone dust collector 2 according to the air volume delivered by the two primary cyclone dust collectors 1 to the secondary cyclone dust collector 2.

[0033] Considering the individual variations in inlet size and cylinder diameter 21, the specific dimensions of the rectangular inlet height *a* and width *b* are related to the processing air volume of the cyclone dust collector. The specific method for calculating the inlet height *a* and width *b* is as follows: , , , Generally speaking, the smaller the diameter D of the cylinder 21, the smaller the rotation radius of the airflow inside the primary cyclone dust collector 1, resulting in greater centrifugal force on the dust particles and improved dust removal efficiency. Conversely, if the diameter of the cylinder 21 is too small, dust-laden gas will escape from the central airflow, reducing dust removal efficiency. There is a certain relationship between the diameter D of the cylinder 21 and the processing air volume Q, as shown in the following formula: .

[0034] The diameter of the exhaust pipe 24 and its insertion depth into the cylinder 21 are both crucial components affecting the performance of the primary cyclone dust collector 1. A smaller diameter results in higher dust removal efficiency, but excessively small diameters lead to increased pressure. Conversely, insufficient insertion depth increases the probability of a "short-circuit flow" in the dust-laden airflow, while excessive depth can create a loop on the outer wall of the exhaust pipe 24, causing falling dust to escape with the rising airflow. Therefore, the diameter D of the exhaust pipe 24 is crucial. e The insertion depth S of the exhaust pipe 24 needs to be kept within a reasonable range: ; .

[0035] The lower end of cone 22 is the ash discharge port. The diameter of the ash discharge port also affects the performance of the cyclone separator. When dealing with high dust concentrations, the ash discharge port diameter is set relatively large to ensure smooth dust particle discharge. However, if the diameter is too large, gas will enter the dust collection device, re-entraining the previously collected dust and reducing dust removal efficiency. Therefore, the ash discharge port diameter B must follow a reasonable range. .

[0036] The height and angle of cone 22 directly affect the turbulence intensity of the cone 22 section. When the radius of rotation decreases, the turbulence intensity increases sharply, and dust particles descending from the wall of cone 22 are easily carried away by the internal swirling flow. Therefore, the height H of cone 22... c The settings should meet the following conditions: , The appropriate height setting of the cylinder 21 of the primary cyclone dust collector 1 is beneficial to increasing the number of rotations of the dust-laden airflow inside the dust collector, thereby increasing the chance of dust separation. The height H of the cylinder 21 a The settings should meet the following conditions: .

[0037] S2. With the inlet height a and width b remaining constant, set different sizes of cylindrical cones 22 with height H.c The optimal proportional relationship between the height of the cone 22 and the diameter of the cylinder 21 was used to simulate the gas phase flow field and the gas-solid two-phase flow. The ratio relationship with the minimum number of escaping particles and the highest separation efficiency was selected as the optimal proportional relationship between the height of the cone 22 and the diameter of the cylinder 21.

[0038] Airflow is caused by pressure difference. When studying the flow characteristics of dust-laden airflow passing through a primary cyclone dust collector 1, the study usually begins with examining the flow properties of dust particles in the airflow and their flow properties within the duct. In ventilation and dust removal engineering practice, the focus is on analyzing the motion characteristics of dust particles within the primary cyclone dust collector 1. This motion is quite complex, depending not only on the physical properties of the dust particles but also closely related to factors such as the cross-sectional area of ​​the cylinder 21, the roughness of the inner wall, and the structural layout of the duct.

[0039] The working principle of the primary cyclone dust collector 1 is as follows: Dust-laden gas enters the primary cyclone dust collector 1 through the inlet channel at a certain speed. The airflow changes from linear motion to circular motion, and spirals downwards along the annular space of the cylinder 21 and the annular space of the cone 22, which is called external swirling flow. During the swirling flow of the dust-laden airflow, a strong centrifugal force is generated. Since the density of dust particles is much greater than that of the gas medium, their inertial effect is significant, causing the dust particles to migrate towards the wall under the action of centrifugal force. When the dust particles collide with the wall, their inertial force disappears, and they mainly rely on the momentum transfer of the inlet airflow and the action of gravity to settle along the wall surface, thereby achieving gas-solid two-phase separation. The separated dust particles enter the dust collection box through the ash discharge port at the bottom of the cone 22. In cone 22, the descending outer swirling flow gradually converges towards the central axis of the primary cyclone dust collector 1 as the flow cross-sectional area decreases. Based on the principle of constant rotational distance, the tangential velocity of the airflow increases as the radius decreases, further enhancing the centrifugal force on the dust particles. When the airflow reaches a critical position in cone 22, its flow state changes, forming an upward spiral flow in the same direction as the initial rotation, called the inner swirling flow. The purified gas is mainly discharged through the top, but during this process, some insufficiently captured dust particles enter the secondary cyclone dust collector 2 with the inner swirling flow, leading to escape.

[0040] In numerical simulation calculations, it is crucial to select an appropriate numerical model for the specific equipment model. For the simulation of the primary cyclone dust collector 1, the main considerations are the selection of a gas-phase turbulence model and a gas-solid two-phase flow model.

[0041] The RSM model was used to simulate the gas phase flow field, abandoning the Boussinesq assumption based on isotropic eddy viscosity, which is suitable for simulating the strong swirling flow inside the first-stage cyclone dust collector 1.

[0042] In the gas-solid two-phase flow field analysis of the primary cyclone dust collector 1, the Euler description method treats the dust-laden medium as a continuous medium field and couples it with particle dynamics theory to calculate the interphase interaction force. This method has high computational efficiency under low particle volume fraction (usually less than 10%).

[0043] In contrast, the discrete phase Lagrange (DPM) model uses a particle trajectory model to perform force analysis and motion trajectory tracking for each discrete particle. This leads to an exponential increase in computational complexity at high dust particle number densities, significantly increasing computational resource consumption. To overcome the limitations of a single method, researchers proposed an Euler-Lagrange coupled algorithm. This algorithm first solves the continuous phase flow field using the Euler framework, and then uses the Lagrange method to track the discrete phase motion, achieving an optimized balance between computational accuracy and efficiency. Based on the above analysis, this study uses the Euler-Lagrange coupled method to numerically simulate the gas-solid two-phase flow within a tunnel dust collector.

[0044] In the field of particle trajectory simulation, based on considerations of turbulent diffusion effects, model systems can be divided into two categories: stochastic trajectory models and deterministic trajectory models. Given that dust particles in the gas-solid two-phase flow within the first-stage cyclone dust collector are prone to trajectory deviation due to the high-speed turbulent field, a stochastic trajectory model is used to predict dust particle trajectories to obtain separation efficiency. Although this model consumes significant computational resources, it can accurately capture the motion characteristics of particles in the turbulent field and has high trajectory prediction accuracy.

[0045] After simulation, the ratio of the minimum number of escaped particles to the highest separation efficiency is selected. If the ratios corresponding to the minimum number of escaped particles and the highest separation efficiency are different, the priority of the highest separation efficiency is greater than the priority of the minimum number of escaped particles.

[0046] S3. With the inlet height a and width b remaining constant, different sizes of exhaust pipes with a diameter D of 24 are installed. e The proportional relationship between the diameter D of the cylinder 21 and the gas phase flow field and the gas-solid two-phase flow was used to simulate the gas phase flow field and the gas-solid two-phase flow. The proportional relationship with the highest separation efficiency was selected as the diameter D of the exhaust pipe 24. e Similarly, the optimal proportional relationship between the insertion depth S of the exhaust pipe 24 and the inlet height a, and the optimal proportional relationship between the ash discharge port diameter B and the diameter D of the cylinder 21 are obtained.

[0047] The diameter of the exhaust pipe 24 is a crucial dimensional parameter in the structure of the primary cyclone dust collector 1. Changes in its size directly affect the interface between the inner and outer cyclones, altering the flow field within the primary cyclone dust collector 1 and consequently impacting its separation performance. Numerical simulation was used to optimize the diameter of the exhaust pipe 24, taking the velocity field, pressure field, pressure drop, and separation efficiency of the primary cyclone dust collector 1 as the basis to derive the optimal value.

[0048] Five sets of parameters were selected for simulation analysis. The diameters of exhaust pipe 24 in each set were: 0.35D, 0.40D, 0.45D, 0.50D, and 0.55D. The inlet height a and width b remained constant. The diameter D of the cylinder 21 was taken as 0.5m, and the height H of the cone 22 was... a and H c Take 1.5D and 2.5D respectively, take the insertion depth S of exhaust pipe 24 as 1.00a, and take the diameter B of ash discharge port as 0.34D.

[0049] The separation efficiency was selected using a single-particle phase injection method with 500 injection point sources, each generating 10 particles, for a total of 5000 particles tracked. The injected dust particle size distribution was Rosin-Rammler. The separation efficiency of each model was calculated by detecting the number of particles escaping from the exhaust port. The particle escape simulation results for each model are shown in Table 1. Table 1. Exhaust pipe diameter models for each group When the diameter of the exhaust pipe 24 increases from 0.35D to 0.40D, the separation efficiency of the dust collector increases from 89.6% to 91.4%. However, when the diameter of the exhaust pipe 24 increases from 0.40D to 0.55D, the separation efficiency decreases from 91.4% to 87.6%. This phenomenon occurs because when the diameter of the exhaust pipe 24 is small, the flow area of ​​the downward swirling flow is large, which leads to a lower tangential velocity of the external swirling flow, which is detrimental to particle separation efficiency. As the diameter of the exhaust pipe 24 increases, the flow area of ​​the external swirling flow decreases, and the tangential velocity of the downward gas increases, which is beneficial to improving particle separation efficiency. When the diameter of the exhaust pipe 24 continues to increase, the flow area of ​​the external swirling flow becomes smaller. At this point, particles near the exhaust pipe 24 are more likely to escape directly from the bottom of the exhaust pipe 24 instead of descending with the external swirling flow. Therefore, when the diameter of the exhaust pipe 24 increases to a certain value, the separation efficiency will decrease with the increase of the diameter of the exhaust pipe 24.

[0050] Considering the actual needs of the engineering site environment, and the requirement to rapidly reduce high dust concentrations within a short period of time, separation efficiency is used as the primary evaluation indicator. Therefore, the exhaust pipe diameter D is 24. e The optimal ratio between the diameter D of the cylinder 21 and the diameter D is 0.40.

[0051] Similarly, the optimal ratio between the insertion depth S of the exhaust pipe 24 and the inlet height a, and the optimal ratio between the ash discharge port diameter B and the cylinder 21 diameter D are obtained.

[0052] S4. Compare the velocity field, pressure field, and separation efficiency of a cyclone dust collector and a combined tunnel pre-dust removal device to obtain the optimal device.

[0053] Modeling a cyclone dust collector and the combined tunnel pre-dust removal device of this invention, and comparing the velocity field, pressure field, and separation efficiency of the two models, we can conclude that: In terms of velocity, the external vortex of the combined tunnel pre-dust removal device is more stable, the "short-circuit" phenomenon below the exhaust pipe 24 is not obvious, and the symmetry and stability of the internal vortex are better than those of a single cyclone separator; in terms of static pressure, the peak static pressure of the combined tunnel pre-dust removal device is 1.1 kPa higher than that of the single-stage cyclone separator, and the internal static pressure distribution does not fluctuate significantly; in terms of separation efficiency, the separation efficiency of the combined tunnel pre-dust removal device is significantly improved compared to that of the single-stage cyclone separator. Therefore, the structural design of the combined tunnel pre-dust removal device is beneficial to dust removal and provides a prerequisite for the subsequent research on combined cyclone series configurations.

[0054] S5. With the device size parameters and connection method unchanged, set the connection angle between different levels, and select the connection angle with the highest separation efficiency as the optimal connection angle.

[0055] Models of primary and secondary cyclone dust collectors 2 were established at angles of 60°, 90°, 120°, 150°, and 180°. The angle represents the angle between the inlet directions of the two primary cyclone dust collectors 1. To reduce airflow disturbance between the two inlets, the inlet heights of the two primary inlets were staggered. The simulation results are shown in Table 2. Table 2. Series Angle Models for Each Group Therefore, it can be seen that when the series angle increases from 60° to 90°, the dust removal efficiency increases from 93.3% to 94.6%. When the series angle increases to 120°, the dust removal efficiency decreases from 94.6% to 92.3%. As the series angle increases to 180°, the dust removal efficiency increases from 92.3% to 96.7%. The reason for this phenomenon is the same as above. When the series angle is 120°, the disturbance of the airflow at the inlet of the secondary cyclone dust collector 2 has a greater impact, and the interface between the inner and outer swirls in the cone 22 part of the primary cyclone dust collector 1 shifts outward too much, which easily leads to "secondary dust" at the bottom of the dust collector, reducing the overall dust removal efficiency of the structure. When the series angle is 180°, the disturbance between the two airflow inlets of the secondary cyclone dust collector 2 has a smaller impact, and the "short circuit" phenomenon at the bottom of the exhaust pipe 24 of the secondary cyclone dust collector 2 is less obvious, and the overall separation efficiency is better.

[0056] Based on the separation efficiency, the influence of the series connection of the structure on the internal regularity of the dust collector was studied, and it was verified that the "2+1" series connection structure of the combined cyclone pre-dust collector has good overall performance; and the optimal series connection angle of the combined cyclone pre-dust collector structure was optimized to 180°.

[0057] The diameter D of the cylinder 21 is taken as the basic value. All other structural parameters of the cyclone dust collector have a certain proportional relationship with it. Based on the tunnel construction conditions, the diameter of the cylinder 21 of the first-stage cyclone dust collector 1 is taken as 0.5m, and the diameter of the cylinder 21 of the second-stage cyclone dust collector 2 is taken as 0.7m.

[0058] The secondary cyclone dust collector 2 has a larger diameter and a higher cone 22, allowing for a longer residence time of the dust-laden gas. This significantly improves the dust removal efficiency for fine dust. Furthermore, the multi-stage series structure increases the volume of the dust collection equipment, which helps to increase the air volume it can handle and speeds up the time required for personnel and equipment to arrive on site.

[0059] Under the constraints of tunnel height and cost, this invention enables the rapid determination of various dimensional parameters of the tunnel pre-dust removal device.

[0060] This invention improves the dust removal efficiency of the tunnel pre-dust removal device by setting the proportional relationship between the dimensions of different parts and the diameter of the cylinder 21.

Claims

1. A combined tunnel pre-dedusting equipment parameter optimization setting method, characterized in that, Comprising the following steps: S1, obtain the single inlet processing air volume Q of the equipment, the inlet air speed V, calculate the height a and width b of the inlet, the cylinder diameter D , simulate the gas phase flow field and the gas-solid two-phase flow, calculate the exhaust pipe insertion depth based on the height a of the inlet S , based on the cylinder diameter D , obtain the cylinder height H a value range, cone height H c , exhaust pipe diameter D e , ash outlet diameter B ; S2, the inlet height a and width b remain unchanged, and the cone height is set to different sizes H c The optimal proportional relationship between the cylinder diameter D The gas phase flow field and gas-solid two-phase flow are simulated, and the proportion relationship with the smallest number of escaped particles and the highest separation efficiency is selected as the optimal proportion relationship between the cylinder cone height and the cylinder diameter. S3, the inlet height a and the width b remain unchanged, and different sizes of exhaust pipe diameter D are set e The gas phase flow field and the gas-solid two-phase flow are simulated in the proportional relationship with the cylinder diameter D, and the highest separation efficiency is selected as the optimal proportional relationship of the exhaust pipe diameter D e In the same way, the optimal proportional relationship of the insertion depth S of the exhaust pipe and the inlet height a, and the optimal proportional relationship of the ash outlet diameter B and the cylinder diameter D are obtained S4, compare the velocity field, pressure field and separation efficiency of a cyclone device and a combined tunnel pre-dust removal device, and obtain the optimal device; S5, the device size parameters and connection mode are unchanged, the connection angle between different levels of cyclone separators is set, the connection angle with the highest separation efficiency is selected as the optimal connection angle.

2. The method according to claim 1, characterized in that, The height a and width b of the calculation entrance in S1, the diameter of the cylinder D The specific method is: ， ， ， 。 3. The method according to claim 1, characterized in that, In S1, the exhaust pipe insertion depth is calculated based on the height a of the inlet S The specific method is: 。 4. The method according to claim 1, wherein, Based on the cylinder diameter D Obtaining the cylinder height H a Value range, cone height H c , Exhaust pipe diameter D e , Ash outlet diameter B The specific method is: ， ， ， 。 5. The method according to claim 1, wherein, The gas phase flow field is simulated by RSM model.

6. The method according to claim 1, wherein The gas-solid two-phase flow is simulated by Euler-Lagrange coupling method.

7. The method according to claim 1, wherein The separation efficiency is obtained based on the trajectory prediction of dust particles, and the trajectory prediction of dust particles is carried out by random trajectory model.

8. The method according to claim 1, wherein, The smallest number of escape particles and the highest separation efficiency are selected in S2, and if the smallest number of escape particles and the highest separation efficiency correspond to different proportional relationships, the priority of the highest separation efficiency is higher than that of the smallest number of escape particles.

9. A combined tunnel pre-dusting apparatus, characterized by, Comprising a two-stage cyclone dust collector and a plurality of one-stage cyclone dust collectors connected therewith; The two-stage cyclone dust collector comprises a vertically arranged cylindrical barrel and a cone with a diameter gradually decreasing from top to bottom vertically arranged below the barrel, the inside of the cone is a cavity, the lower end is a dust discharge port, the top of the barrel is closed and connected with a downwardly opening air duct, the end of the air duct away from the top of the barrel is connected with an extraction fan, a plurality of tangential inlet channels with stepped height distribution are arranged on the barrel, and the tangential inlet channels are communicated with the top of the one-stage cyclone dust collector through exhaust pipes; The one-stage cyclone dust collector also comprises a vertically arranged cylindrical barrel and a cone with a diameter gradually decreasing from top to bottom vertically arranged below the barrel, and further comprises a one-stage dust-containing gas inlet channel tangentially communicated with the barrel; The size of the barrel and the cone of the two-stage cyclone dust collector is larger than that of each one-stage cyclone dust collector.

10. The combined tunnel pre-dust removal device according to claim 9, characterized in that, The maximum diameter of the cone of the two-stage cyclone dust collector and the one-stage cyclone dust collector above the barrel is the same as the diameter of the inner wall of the barrel.

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