Deep vertical shaft double-air-duct press-in type air supply air duct position optimization method

Abstract

The invention provides a deep vertical shaft double-air-duct press-in type air supply air duct position optimization method which comprises the following steps: (1) collecting parameters of a vertical shaft and air ducts, and calculating the blasting smoke throwing distance and the generated CO initial concentration according to the amount of explosive needed by blasting; (2) constructing a physical model matched with actual engineering parameters by adopting numerical simulation software based on the component transportation model, and setting different relative arrangement positions of double air ducts; (3) analyzing the derived simulation data at different moments and the related visual cloud atlas, counting the CO concentration condition in the working area, and fitting a curve of the CO concentration changing along with time; and (4) by taking the CO safe concentration threshold value as a reference, analyzing the ventilation time required by the standard reaching of the CO concentration of the operation area under each arrangement working condition, sorting and drawing a chart. According to the method, the ventilation efficiency change characteristics under different air duct arrangement angles can be effectively determined, and scientific reference is provided for optimal air duct arrangement scheme selection of various deep vertical shaft engineering double-air-duct press-in type air supply systems.

Description

Technical Field

[0001] This invention relates to the field of deep shaft ventilation technology, specifically a method for optimizing the position of a deep shaft dual-duct forced air supply duct. Background Technology

[0002] Deep shaft construction is characterized by a closed environment and poor air circulation, generating large amounts of CO gas during blasting operations. This gas is highly toxic and diffuses rapidly; if not effectively and promptly removed, it can easily cause poisoning and asphyxiation accidents among construction workers, seriously threatening underground construction safety. Due to the significant depth of ultra-deep shafts, ventilation systems face numerous challenges: ventilation resistance increases significantly with shaft depth, leading to increased ventilation power loss and a substantial reduction in CO gas removal efficiency. To improve ventilation, projects typically add additional ventilation ducts to a single-duct ventilation system, employing a double-duct forced-in ventilation mode. However, traditional double-duct forced-in ventilation designs have core flaws: firstly, the duct arrangement lacks scientific theoretical support, often using a parallel (0°) arrangement, causing fresh air to form a vortex area within the shaft, making efficient CO gas dilution and removal difficult; secondly, the airflow from the two ducts interferes with each other, further reducing ventilation efficiency, and existing technologies lack a clear quantitative correlation between the duct arrangement angle and CO removal efficiency, failing to provide effective guidance for duct arrangement design.

[0003] In summary, optimizing the layout of the dual ventilation ducts is a key technical issue for improving the ventilation efficiency of ultra-deep vertical shafts and ensuring construction safety, and a scientific and effective solution is urgently needed. Summary of the Invention

[0004] To address the aforementioned technical shortcomings, the purpose of this invention is to provide a method for optimizing the location of a deep vertical shaft dual-ventilation forced-in air supply duct, thereby improving ventilation efficiency during deep vertical shaft construction.

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

[0006] A method for optimizing the location of a deep vertical shaft dual-duct forced air supply duct includes the following steps:

[0007] S1. Collect and calculate relevant parameters based on the actual background;

[0008] S2. Construct a vertical shaft double ventilation model;

[0009] S3. Complete the flow field and data analysis inside the well;

[0010] S4. Measure ventilation efficiency by the shortest time to reach a safe concentration.

[0011] Preferably, in step S1, collecting and calculating relevant parameters in conjunction with the actual background specifically includes the following steps:

[0012] S1.1. Based on the engineering background, select basic data including vertical shaft structural parameters and ventilation duct performance parameters, select a 2m range at the bottom of the vertical shaft as the core working area for the workers, and set this area as the main research object for the CO concentration variation law;

[0013] S1.2 Calculate the throwing distance of the blasting smoke and the initial concentration of CO generated based on the amount of explosives required for the blast.

[0014] Preferably, in step S2, constructing the vertical shaft double-duct ventilation model specifically includes the following steps:

[0015] S2.1 The vertical shaft dual-duct ventilation model is simplified, and the CO throwing area is taken as the main body of the model. The CO component transport model is started, and the RNGk-ε turbulence model is used to simulate the gas phase flow. The governing equations include the mass conservation equation and the momentum conservation equation. The model is meshed using a structured grid, and the grid independence is verified to determine the number of grids.

[0016] S2.2 Arrange the relative positions of the ventilation ducts according to the viewing angle from above, setting them to 0°, 30°, 60°, 90°, 120°, 150°, and 180° respectively;

[0017] S2.3. Use software to perform numerical calculations; perform calculations for different working conditions separately, start transient calculations, set boundary conditions, locally initialize the CO concentration in the well, output data at specific times in real time, enable CO concentration volume average integral report detection, and statistically analyze the shortest time to reach the safe concentration.

[0018] Preferably, in step S3, the flow field and data analysis within the well specifically includes the following steps:

[0019] S3.1 Export CO concentration cloud maps for each operating condition at different times and observe the change process of CO concentration;

[0020] S3.2 Calculate the volume integral of CO concentration in the area 2m away from the working surface at each time point, record the data and fit a curve of CO concentration change over time.

[0021] Preferably, in step S4, in measuring ventilation efficiency by the shortest time to reach a safe concentration, 24 ppm is used as the CO safe concentration threshold, and the shortest time required for the work area to reach a safe concentration is recorded, thereby measuring the level of ventilation efficiency by this shortest time.

[0022] Preferably, in step S2.1, the mass conservation equation states that the mass of the net fluid element is equal to the rate of change of fluid mass, and the total fluid mass is continuous during motion. The mathematical expression is:

[0023]

[0024] In the formula: ρ is the air density; t is the time; x, y, z are rectangular coordinates; μ, v, ω are the velocity components in the x, y, and z directions.

[0025] Preferably, in step S2.1, the momentum conservation equation is:

[0026]

[0027] In the formula, p is the pressure on the surface of the fluid element; ρ is the density; u x u y u z τ represents the velocity components in the x, y, and z directions; ij Let f be the viscous stress components on the surface of the infinitesimal element (i, j = x, y, z); x f y f z This refers to the unit mass force in three directions.

[0028] Preferably, in step S2.1, the key governing equations of the RNG k-ε turbulence model are:

[0029] Turbulent kinetic energy transport equation k:

[0030] ;

[0031] In the formula, x i x j Let i be a rectangular coordinate system (i, j=1, 2, 3 correspond to the x, y, z directions of the rectangular coordinate system, respectively); k is the turbulent kinetic energy; u i For the average velocity component; α k μ is the reciprocal of the Prandtl number in the turbulent kinetic energy k-equation; eff G is the effective viscosity coefficient; k G is the turbulent kinetic energy term generated by the average velocity gradient. b Y is the turbulent kinetic energy term generated by buoyancy; ε is the turbulent dissipation rate; M For the dissipation term of compressible fluid pulsating expansion; S k For custom source items.

[0032] The transport equation for dissipation rate ε:

[0033] ;

[0034] In the formula, x i x j This is a rectangular coordinate system (i, j=1, 2, 3 correspond to the x, y, z directions of the rectangular coordinate system, respectively); u iFor the average velocity component; α ε μ is the reciprocal of the Prandtl number in the turbulent kinetic energy equation; eff ε is the effective viscosity coefficient; ε is the turbulent dissipation rate; C 1ε C 2ε The model constants are 1.42 and 1.68, respectively; C 3ε G is a constant related to buoyancy. k G is the turbulent kinetic energy term generated by the average velocity gradient. b R represents the turbulent kinetic energy term generated by buoyancy; R is the core correction term of the RNG model; S ε This is a custom source item.

[0035] Preferably, in step S2.1, without considering the heat transfer of CO flowing in the shaft, no chemical reaction or phase change reaction occurs during the dilution and diffusion process, the CO mass remains constant, and the mathematical equation for CO component transport is expressed as:

[0036] ;

[0037] In the formula, c s This refers to the volume concentration of the component. D is the velocity vector; s S is the diffusion coefficient; s is the component productivity per unit volume per unit time; div and grad are the divergence and gradient operators, respectively.

[0038] Preferably, in step S2.3, the numerical calculation using software specifically includes the following steps: importing the mesh model into the relevant software, setting the gravity, turbulence model and discrete phase model in sequence, adding air and CO material, setting the outlet wind speed of the two ducts, starting transient calculation, locally initializing the CO concentration in the well, outputting data every 100s, and enabling the CO concentration volume average integral report detection, which can more intuitively monitor the CO concentration at each moment.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] A physical model was established through numerical calculations to analyze the air turbulence effect on the flow field, further impacting CO removal. The relationship between the ventilation duct layout and ventilation efficiency was verified, and an optimal 180-degree ventilation duct layout angle was proposed. By using this layout optimization method, the most favorable ventilation duct layout can be set according to different working conditions, avoiding the most unfavorable situations, improving ventilation efficiency, rapidly removing harmful gases, and ensuring the safety of mine operations. Attached Figure Description

[0041] Figure 1 This is a flowchart illustrating the process of the method of the present invention;

[0042] Figure 2 This is a schematic diagram of the ventilation duct layout;

[0043] Figure 3 This is a cloud map showing the CO concentration distribution at different times within a 90° radius;

[0044] Figure 4 This is a cloud map showing the CO concentration distribution at different times within a 180° radius;

[0045] Figure 5 A trend chart of CO concentration at different arrangement positions;

[0046] Figure 6 A schematic diagram showing the shortest time required to reach a safe concentration for different arrangement positions. Detailed Implementation

[0047] The invention will now be further described with reference to the accompanying drawings.

[0048] like Figure 1 As shown, a method for optimizing the position of a deep vertical shaft dual-duct forced air supply duct includes the following steps:

[0049] S1. Collect and calculate relevant parameters based on the actual background.

[0050] S1.1. Based on the background of a certain project, select basic data such as vertical shaft structural parameters and ventilation duct performance parameters, select a 2m range at the bottom of the vertical shaft as the core working area for the workers, and set this area as the main research object for the CO concentration variation law.

[0051] S1.2 Calculate the throwing distance of the blasting fumes and the initial CO concentration based on the amount of explosives required for the blast. During shaft excavation and blasting, harmful gases produced include CO and nitrogen oxides. However, because CO is more stable than other harmful gases, it is often used as the primary gas for calculation in construction ventilation. Other harmful nitrogen oxide gases are converted to CO at a ratio of 1:6.5. For ease of calculation, it is assumed that CO is uniformly distributed within the blasting fume throwing range at the initial moment. Therefore, the mass fraction of CO is calculated using the following formula:

[0052] ;

[0053] In the formula: C0 is the initial concentration of CO, G is the amount of explosive used, b is the amount of harmful gas produced per unit mass of explosive (converted to CO), L is the length of the blasting smoke throwing zone, according to previous research, L = 15 + G / 5 when using electric detonators; A is the cross-sectional area of ​​the shaft excavation. The calculated blasting smoke throwing distance is 50m, and the initial CO mass fraction is 0.0017.

[0054] S2. Construct a vertical shaft double-ventilation model, including the following specific processes:

[0055] S2.1 To save computational resources, the model is simplified, taking the CO throwing area, i.e., the 50m range at the bottom of the shaft, as the main body of the model. The shaft diameter is 10m, the ventilation duct diameter is 1.2m, and the length is 25m, suspended at the inlet 10cm from the right boundary. The CO component transport model is activated, and the RNGk-ε turbulence model simulates the gas phase flow. The governing equations include the mass conservation equation and the momentum conservation equation. A structured mesh is used to generate the model, and mesh independence is verified to determine a reasonable number of meshes.

[0056] S2.2 Arrange the relative positions of the ventilation ducts according to the viewing angle from above, setting them to 0° (i.e., two ventilation ducts side by side), 30°, 60°, 90°, 120°, 150°, and 180° respectively. A schematic diagram of the ventilation duct arrangement is shown below. Figure 2 As shown.

[0057] S2.3. Numerical calculations are performed using software. Calculations are performed separately for different operating conditions. Transient calculations are initiated, boundary conditions are set, the inlet wind speed is 10 m / s, and the CO concentration in the well is initialized locally. By default, CO is instantly and uniformly filled within the throwing distance range after the blast. Data at specific moments is output in real time every 100 seconds, and CO concentration volume average integral report detection is enabled for more intuitive monitoring of CO concentration at each moment.

[0058] S3. Complete the flow field and data analysis inside the well;

[0059] S3.1 Export the CO concentration cross-sectional contour maps for each operating condition at different times, taking 90° and 180° as examples. Figure 3 , Figure 4 As shown, the change in CO concentration inside the well can be clearly seen.

[0060] S3.2 Calculate the CO concentration volume integral within a 2m radius of the working surface at each time point, record the data, and fit a curve graph as shown below. Figure 5 As shown, the CO concentration gradually decreases with increasing time under all operating conditions, with the highest concentration at 90° and the lowest at 180°. This indicates that from 0 to 90°, the turbulence effect of the airflow gradually weakens, and its CO removal effect also gradually weakens. From 90 to 180°, a relatively stable flow field gradually forms inside the well, and the removal efficiency gradually increases.

[0061] S4. Measure ventilation efficiency by the shortest time required to reach a safe concentration. The safe concentration threshold for human exposure to CO is 24 ppm, and this value is used as the core standard for judging whether the CO concentration in the work area meets the standard. By monitoring the changes in CO concentration within the work area under different working conditions, the shortest time required for the CO concentration to drop to 24 ppm is determined, and this is used as a key indicator to quantify ventilation efficiency. The data is then fitted into a chart, such as... Figure 6 As shown, the time required for the working area to reach a safe concentration gradually increases from 0 to 90° and gradually decreases from 90 to 180°. The ventilation time at 180° is less than that at 0°, so the ventilation efficiency is highest at 180° and lowest at 90°.

Claims

1. A method for optimizing the position of a deep vertical shaft dual-duct forced air supply duct, characterized in that, Includes the following steps: S1. Collect and calculate relevant parameters based on the actual background; S2. Construct a vertical shaft double ventilation model; S3. Complete the flow field and data analysis inside the well; S4. Measure ventilation efficiency by the shortest time to reach a safe concentration.

2. The method for optimizing the position of a deep vertical shaft dual-duct forced air supply duct as described in claim 1, characterized in that, In step S1, the relevant parameters are collected and calculated in conjunction with the actual background, specifically including the following steps: S1.

1. Based on the engineering background, select basic data including vertical shaft structural parameters and ventilation duct performance parameters, select a 2m range at the bottom of the vertical shaft as the core working area for the workers, and set this area as the main research object for the CO concentration variation law; S1.2 Calculate the throwing distance of the blasting smoke and the initial concentration of CO generated based on the amount of explosives required for the blast.

3. The method for optimizing the position of a deep vertical shaft dual-duct forced air supply duct as described in claim 1, characterized in that, In step S2, constructing the vertical shaft dual-ventilation model specifically includes the following steps: S2.1 The vertical shaft dual-ventilation model is simplified, and the CO throwing area is taken as the main body of the model. The governing equations include the mass conservation equation and the momentum conservation equation. The RNG k-ε turbulence model and the CO component transport model are enabled. The model is meshed using a structured grid, and the grid independence is verified to determine the number of grids. S2.2 Arrange the relative positions of the ventilation ducts according to the viewing angle from above, setting them to 0°, 30°, 60°, 90°, 120°, 150°, and 180° respectively; S2.

3. Use software to perform numerical calculations; perform calculations for different working conditions separately, start transient calculations, set boundary conditions, locally initialize the CO concentration in the well, output data at specific times in real time, enable CO concentration volume average integral report detection, and statistically analyze the shortest time to reach the safe concentration.

4. The method for optimizing the position of a deep vertical shaft dual-duct forced air supply duct as described in claim 1, characterized in that, In step S3, the flow field and data analysis within the well specifically includes the following steps: S3.1 Export CO concentration cloud maps for each operating condition at different times and observe the change process of CO concentration; S3.2 Calculate the volume integral of CO concentration in the area 2m away from the working surface at each time point, record the data and fit a curve of CO concentration change over time.

5. The method for optimizing the position of a deep vertical shaft dual-duct forced air supply duct as described in claim 1, characterized in that, In step S4, in measuring ventilation efficiency by the shortest time to reach a safe concentration, 24 ppm is used as the CO safe concentration threshold, and the shortest time required for the work area to reach a safe concentration is recorded. The ventilation efficiency is measured by this shortest time.

6. The method for optimizing the position of a deep vertical shaft dual-ventilation forced-flow air duct as described in claim 2, characterized in that, In step S2.1, the mass conservation equation states that the mass of the net fluid element is equal to the rate of change of fluid mass, and the total fluid mass is continuous during motion. The expression is: ； In the formula, ρ is the air density; t is the time; x, y, z are rectangular coordinates; μ, v, ω are the velocity components in the x, y, and z directions.

7. The method for optimizing the position of a deep vertical shaft dual-duct forced air supply duct as described in claim 2, characterized in that, In step S2.1, the mathematical expression of the momentum conservation equation is: ； In the formula, p is the pressure on the surface of the fluid element; ρ is the density; u x u y u z τ represents the velocity components in the x, y, and z directions; ij Let f be the viscous stress components on the surface of the infinitesimal element (i,j = x, y, z); x f y f z This refers to the unit mass force in three directions.

8. The method for optimizing the position of a deep vertical shaft dual-ventilation forced-flow air duct as described in claim 2, characterized in that, In step S2.1, the key governing equations of the RNG k-ε turbulence model are: Turbulent kinetic energy transport equation k: ； In the formula, x i x j Let i be a rectangular coordinate system, j = 1, 2, 3, corresponding to the x, y, and z directions of the rectangular coordinate system, respectively; k is the turbulent kinetic energy; u i For the average velocity component; α k μ is the reciprocal of the Prandtl number in the turbulent kinetic energy k-equation; eff G is the effective viscosity coefficient. k G is the turbulent kinetic energy term generated by the average velocity gradient. b Y is the turbulent kinetic energy term generated by buoyancy; ε is the turbulent dissipation rate; M For the dissipation term of compressible fluid pulsating expansion; S k For user-defined source items. The transport equation for dissipation rate ε: ； In the formula, u i For the average velocity component; α ε μ is the reciprocal of the Prandtl number in the turbulent kinetic energy equation; eff ε is the effective viscosity coefficient; ε is the turbulent dissipation rate; C 1ε C 2ε The model constants are 1.42 and 1.68, respectively; C 3ε G is a constant related to buoyancy. k G is the turbulent kinetic energy term generated by the average velocity gradient. b R represents the turbulent kinetic energy term generated by buoyancy; R is the core correction term of the RNG model; S ε Define the source term.

9. The method for optimizing the position of a deep vertical shaft dual-ventilation forced-flow air duct as described in claim 2, characterized in that, In step S2.1, without considering the heat transfer of CO flowing in the shaft, no chemical reaction or phase change reaction occurs during the dilution and diffusion process, the CO mass remains constant, and the mathematical equation for CO component transport is expressed as: ； In the formula, c s This refers to the volume concentration of the component. D is the velocity vector; s S is the diffusion coefficient; s is the component productivity per unit volume per unit time; div and grad are the divergence and gradient operators, respectively.

10. The method for optimizing the position of a deep vertical shaft dual-duct forced air supply duct as described in claim 2, characterized in that, In step S2.3, the numerical calculation using software specifically includes the following steps: importing the mesh model into the relevant software, setting the gravity, turbulence model and discrete phase model in sequence, adding air and CO material, setting the outlet wind speed of the two ducts, starting transient calculation, locally initializing the CO concentration in the well, outputting data every 100s, and enabling the CO concentration volume average integral report detection, which can more intuitively monitor the CO concentration at each moment.

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