Automatic wind direction adjusting method for air outlet of mine air curtain

Abstract

The invention discloses a method for automatically adjusting the air direction of an air outlet of a mine air curtain, which comprises the following steps of: (1) arranging an air outlet adjusting device and an air curtain in a roadway in which air flow needs to be blocked, injected and increased, pressure sensors are installed on the front side and the rear side of the position where airflow needs to be partitioned in the roadway, and the partition pressure difference H1 of the two sides of the position where airflow needs to be partitioned is measured; (2) calculating the actual pressure H2 generated by the mining air curtain at the position needing to block the air flow in the roadway, wherein H2 is approximately equal to k * (rho * Q * v * cos theta) / A; and (3) comparing the H1 with the H2 by using a PLC control system. The mine air curtain air outlet adjusting device has the beneficial effects that different control strategies can be selected to operate the air outlet adjusting device according to partition pressure difference changes caused by dynamic changes of a mine ventilation system, and the wind direction of the mine air curtain air outlet can be adjusted as needed.

Description

Technical Field

[0001] This invention relates to the field of mine ventilation technology, specifically to a method for automatically adjusting the air direction of a mine air curtain outlet. Background Technology

[0002] Mine ventilation refers to the process of introducing fresh air into the mine to increase oxygen concentration, thereby diluting and removing toxic and harmful gases and dust. The basic task of mine ventilation is to continuously supply sufficient fresh air underground, dilute and remove various toxic and harmful gases and mine dust, ensure the health of miners, improve labor productivity, create a good working environment, and achieve the goal of safe production.

[0003] Mining air curtains function as ventilation doors, while the ejected airflow acts as auxiliary fans. They are commonly used in roadways where auxiliary fans are required but cannot obstruct transportation or pedestrian traffic. Currently, when using air curtains for ventilation in underground mines, the actual placement of the jet boxes within the roadway and the orientation of the air curtain outlets are usually fixed. This makes it impossible to adjust the initial jet angle and the outlet air velocity of the air curtain. Consequently, the air exiting the variable-diameter diffuser outlet always blows in one direction, making it impossible to flexibly adjust the pressure difference created by the air curtain at the airflow interruption point in the roadway according to changes in the underground ventilation network and air pressure. This hinders the effective functions of blocking, ejecting, increasing airflow in the roadway, and reducing roadway resistance. Therefore, how to match the pressure difference changes caused by dynamic changes in the mine ventilation system with the pressure difference generated by the mining air curtain, and how to find effective technical methods for airflow control in underground transportation roadways, has become an urgent problem for mines.

[0004] Currently, there are two main methods for automatically adjusting the air direction at the outlet of a mine air curtain: The first type is a research report on mine air curtains published by Meng Han et al. in the November 2017 issue of the journal *Coal*, outlining a new type of mine air curtain system. This system consists of an extraction system, a forced-in system, and an air curtain jet system. The extraction system comprises an extraction duct, an exhaust fan, and a dust collector; the forced-in system consists of a compressor and a compressor duct; and the air curtain jet system consists of an air curtain jet box. Fresh air enters the forced-in duct through the compressor, and the air curtain jets the air onto the tunnel face. The jet box contains an adjustable baffle to regulate the outlet air velocity and angle of the air curtain. However, because changes in the baffle angle alter the airflow at the air curtain outlet, it fails to effectively induce airflow and increase airflow in the tunnel.

[0005] The second type is an automatic air curtain regulating device for mines, disclosed in Chinese Utility Model Patent Publication No. CN203640758U. This device includes a fan, a wind pressure sensor, and a control device. The fan is installed in the mine chamber, with its outlet facing opposite to the wind direction. The wind pressure sensor is installed in the mine roadway, located between the roadway inlet and the fan. The signal output of the wind pressure sensor is connected to the control signal input of the control device, and the control signal output of the control device is connected to the control terminal of the fan. This forms an air curtain, leveling the wind pressure in the roadway and effectively isolating the airflow. However, because this regulating device uses a variable frequency drive (VFD) to control the air curtain, it has high requirements for the installation environment and is only applicable to the fresh air side. In polluted air environments, the VFD is prone to malfunction, making management difficult. Summary of the Invention

[0006] The technical problem to be solved by the present invention is that the pressure difference caused by the dynamic changes of the mine ventilation system is difficult to match with the pressure difference generated by the mine air curtain in the prior art. To this end, an automatic adjustment method for the air direction of the mine air curtain outlet is provided.

[0007] The technical solution of the present invention is: an automatic wind direction adjustment method for the air outlet of a mine air curtain, comprising the following steps: (1) setting an air outlet adjustment device and an air curtain in a roadway where airflow needs to be blocked, ejected, or increased. The air outlet adjustment device is used to drive the air curtain to rotate horizontally. Pressure sensors are installed on both sides of the roadway where airflow needs to be blocked to measure the pressure difference ΔH1 between the two sides where airflow needs to be blocked; (2) calculating the actual pressure ΔH2 generated by the mine air curtain at the point where airflow needs to be blocked in the roadway, ΔH2 ≈ k × (ρ × Q × v × cosθ) / A, where: △H2: isolation pressure difference, k: mine scene correction coefficient, ρ: air density, Q: air curtain air volume, v: outlet wind speed, θ: installation angle, A: airflow action cross-sectional area; (3) Using the PLC control system for comparison, when △H1≥(1.0-1.2)△H2, the PLC control system drives the outlet adjustment device to drive the air curtain to rotate towards the center line of the roadway until △H1 approaches (1.0-1.2)△H2; when △H1<(1.0-1.2)△H2, the PLC control system drives the outlet adjustment device to drive the air curtain to rotate towards the roadway side until △H1 approaches (1.0-1.2)△H2.

[0008] The PLC control system described above has a human-machine interactive visualization interface that can display the comparison results of △H1 and △H2.

[0009] The air curtain described in the above scheme includes a mine axial flow fan and a variable diameter diffuser.

[0010] The PLC control system described in the above scheme is located in the ground dispatch center and is connected to the pressure sensor and the air outlet adjustment device.

[0011] The pressure sensors described in the above scheme are spaced 2m-3m apart, suspended at the intersection of the roadway centerline and the waistline, with the acquisition holes aligned with the direction of the incoming airflow, and the static pressure difference between the two sides can be measured.

[0012] The air outlet adjustment device described in the above scheme includes a fixed frame, an installation plate installed inside one end of the fixed frame, a fixed base fixedly connected to the center of the installation plate, the top of the fixed base being rotatably connected to the mine axial flow fan via a rotating shaft, a movable arm extending axially inside the fixed frame, the two ends of the movable arm being respectively mounted plates and slidably connected to one end of the fixed frame, an electric telescopic rod being fixedly connected to the outside of the fixed frame and driven by the movable arm, and the upper surface of the end of the movable arm away from the mine axial flow fan being fixedly connected to a variable diameter diffuser.

[0013] In the above scheme, the value of k is between 0.8 and 1.2.

[0014] The value of ρ in the above scheme is between 1.2 kg / m³ and 1.3 kg / m³.

[0015] In the above scheme, the value of Q is determined by the machine number.

[0016] In the above scheme, the value of A is approximately equal to the net cross-sectional area of ​​the tunnel.

[0017] The beneficial effects of this invention are as follows: Based on the changes in the isolation pressure difference caused by the dynamic changes in the mine ventilation system, and by synchronously comparing the isolation pressure difference ΔH1 monitored by the pressure sensing system with the isolation pressure difference ΔH2 calculated by the isolation pressure difference calculation model, different control strategies can be selected to operate the outlet adjustment device, enabling on-demand adjustment of the airflow direction of the mine air curtain outlet. A preset value can be set; if the difference between the calculated value and the monitored value is greater than the preset value, the PLC control system drives the outlet adjustment device, causing the air curtain to rotate towards the center line of the roadway; if the difference between the calculated value and the monitored value is less than the set safety value, the PLC control system drives the outlet adjustment device, causing the air curtain to rotate towards the roadway side, realizing multiple modes of mine air curtain outlet control strategies. Furthermore, the electric telescopic rod drives the moving arm to move, and the moving arm drives the variable diameter diffuser to rotate around the mine axial flow fan, further improving the reliability and stability of the air curtain's isolation of airflow, making it more practical. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the system framework of the present invention; Figure 2 This is a flowchart of the method of the present invention; Figure 3 This is a schematic diagram showing the interaction between the air curtain and the air outlet adjustment device of the present invention; Figure 4 for Figure 3 Top view; In the diagram: 1. Air curtain; 11. Mine axial flow fan; 12. Variable diameter diffuser; 2. PLC control system; 3. Pressure sensing system; 4. Differential pressure calculation model; 5. Air outlet adjustment device; 51. Fixed frame; 52. Fixed base; 53. Rotating shaft; 54. Moving arm; 55. Electric telescopic rod; 56. Mounting plate. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments implemented by those skilled in the art without creative effort are within the protection scope of the present invention.

[0021] like Figure 1 , Figure 2 As shown in the embodiment of the present invention: an automatic air direction adjustment method for the air outlet of a mine air curtain is provided, including an air curtain 1, a PLC control system 2, a pressure sensing system 3, a differential pressure calculation model 4, and an air outlet adjustment device 5. The air curtain 1, the pressure sensing system 3, and the air outlet adjustment device 5 are arranged in the roadway where airflow needs to be blocked, ejected, or increased. The PLC control system 2 and the differential pressure calculation model 4 are integrated into the surface dispatch center.

[0022] The PLC control system can remotely control the automatic adjustment of the airflow direction at the mine air curtain outlet. The pressure sensing system consists of pressure sensors and related accessories. The isolation pressure difference calculation model is based on the apparent momentum corresponding to the selected air curtain unit number and installation angle, the cross-sectional area of ​​the air supply outlet, and the cross-sectional area of ​​the roadway where the airflow needs to be isolated. In the engineering application of air curtains, "apparent momentum" refers to the portion of momentum that actually has an effect on the airflow within the target area. It is a key indicator for judging whether the airflow barrier can effectively block indoor and outdoor air convection. Factors such as the installation angle of the airflow and the natural attenuation during propagation will subtly change the actual effectiveness of momentum, ultimately precipitating into what we call "apparent momentum." The specific calculation formula is as follows: △H2 ≈ k × (ρ × Q × v × cosθ) / A, where: △H2: isolation pressure difference, k: mine scenario correction coefficient (0.8-1.2, adjusted according to roadway wind speed, higher value is taken when wind speed is high), ρ: air density (usually 1.2-1.3 kg / m³ underground, needs to be corrected according to altitude and temperature), Q: air curtain air volume (m³ / s, determined by machine number), v: outlet wind speed (m / s), θ: installation angle (angle with the perpendicular direction of the roadway cross-section), A: cross-sectional area of ​​airflow action (m², approximately equal to the net cross-sectional area of ​​the roadway). Figure 3 , Figure 4 As shown, the air outlet adjustment device has a fixed frame 51. An installation plate 56 is installed inside one end of the fixed frame. A fixed base 52 is fixedly connected to the center of the installation plate. The top of the fixed base is rotatably connected to the mine axial flow fan via a rotating shaft 53. A movable arm 54 extends axially within the fixed frame. The two ends of the movable arm are respectively mounted on plates and slidably connected to one end of the fixed frame. An electric telescopic rod 55, which is drively connected to the movable arm, is fixedly connected to the outside of the fixed frame. The upper surface of the end of the movable arm away from the mine axial flow fan is fixedly connected to a variable diameter diffuser. The electric telescopic rod pushes the movable arm to move within the fixed frame. The movable arm drives the variable diameter diffuser and the mine axial flow fan to rotate around the rotating shaft, thereby achieving automatic adjustment of the airflow direction at the air curtain outlet. This can block, guide, and increase airflow in the roadway, and reduce roadway resistance. The fixed frame is rectangular; its two shorter sides can be called the two ends, and its two longer sides can be called the two sides. The upper surface of the movable arm is fixed to the variable diameter diffuser by bolts.

[0023] In the above embodiments, the present invention can select different control strategies to adjust the outlet direction of the variable diameter diffuser according to the pressure changes at the airflow isolation point in the underground roadway, thereby achieving on-demand adjustment of the airflow direction at the air curtain outlet. This provides support for the management of mine ventilation systems.

[0024] The PLC control system 2 compares the isolation pressure difference monitored by the pressure sensing system 3 through a human-machine interactive visual interface. The partition pressure difference ΔH2 that the air curtain 1 can generate is calculated by model 4, which is based on ΔH1 and partition pressure difference calculation model 4.

[0025] When ΔH1 ≥ (1.0-1.2)ΔH2, the PLC control system 2 drives the outlet adjustment device 5, which in turn drives the variable diameter diffuser and the mine axial flow fan to rotate around the shaft centerline of the roadway, causing the air curtain 1 outlet to rotate, thus achieving automatic adjustment of the airflow direction at the air curtain outlet. When ΔH1 ≤ (1.0-1.2)ΔH2, the PLC control system 2 drives the outlet adjustment device 5, which, through the moving arm, drives the air curtain 1 outlet to rotate, thus achieving automatic adjustment of the airflow direction at the air curtain outlet.

[0026] In this embodiment of the invention, the mine air curtain 1 is composed of a mine axial flow fan 11 and a variable diameter diffuser 12. Fresh air enters the variable diameter diffuser through the mine axial flow fan and is sprayed into the roadway in the form of a jet, forming a jet barrier in front of the roadway, which can play the role of blocking, guiding, increasing the airflow in the roadway, and reducing the roadway resistance.

[0027] In this embodiment of the invention, the PLC control system 2 is located in the ground dispatch center and consists of data logic operations, a human-machine interface, and ventilation system management and early warning.

[0028] In this embodiment of the invention, the pressure sensing system 3 consists of pressure sensors installed in the roadway at the points where airflow needs to be isolated. The pressure sensors are arranged on both sides of the roadway before and after the airflow isolation point, with a spacing of 2m-3m. The suspension position is located at the intersection of the roadway centerline and the waist-high line. During installation, the respective plugs are first connected, and then they are mounted on the bracket for fixation. The acquisition hole is aligned with the incoming airflow direction to measure the static pressure difference between the two sides.

[0029] In this embodiment of the invention, the following steps are included: Step 1: Input the model number of the selected mine air curtain 1 and the apparent momentum of the installation angle, the cross-sectional area of ​​the air curtain air supply outlet, etc. through the human-computer interaction visual interface to obtain the pressure calculation value of the selected mine air curtain 1 at the partition. Step 2: The pressure sensing system 3 monitors the pressure value at the point in the roadway where airflow needs to be cut off and transmits the pressure value to the human-machine interface. The calculated pressure value is compared with the monitored value. If the difference between the calculated value and the monitored value is greater than the set value, the PLC control system 2 drives the outlet adjustment device 5 to move the moving arm. The moving arm drives the variable diameter diffuser to rotate around the mine axial flow fan, thereby realizing the automatic adjustment of the airflow direction of the mine air curtain outlet until it approaches the preset value.

[0030] Step 3: If the difference between the calculated value and the monitored value is less than the set value, the PLC control system 2 drives the air outlet adjustment device 5, which drives the movable frame and the fixed base to rotate around the rotating axis to the roadway side. Through the clamping arm, the air outlet of the air curtain 1 is rotated, thereby realizing the automatic adjustment of the air direction of the mine air curtain until it approaches the preset value.

[0031] In the above embodiments, by Figure 2 As can be seen, this invention can accurately describe the pressure changes at the airflow isolation point in underground roadways, select different control strategies to adjust the outlet direction of the air curtain variable diameter diffuser, and realize on-demand adjustment of the airflow direction at the outlet of the variable diameter diffuser. Simultaneously, it enables the local area network publication of air curtain operating parameters.

[0032] Working principle: The present invention provides an automatic air direction adjustment method for the air outlet of a mine air curtain. Based on the change in isolation pressure difference caused by the dynamic changes of the mine ventilation system, the method synchronously compares the isolation pressure difference ΔH1 (Pa) monitored by the pressure sensing system with the isolation pressure difference ΔH2 (Pa) that the mine air curtain can generate, calculated by the isolation pressure difference calculation model. Different control strategies are selected to operate the air outlet adjustment device, which can realize the on-demand adjustment of the air direction of the mine air curtain air outlet.

[0033] Secondly, in order to achieve mine air curtain outlet control under multiple modes, a preset value is set. If the difference between the calculated value and the monitored value is greater than the preset value, the PLC control system drives the outlet adjustment device to rotate the variable diameter diffuser towards the center line of the roadway; if the difference between the calculated value and the monitored value is less than the set safety value, the PLC control system drives the outlet adjustment device to rotate the variable diameter diffuser towards the roadway side, which is more practical.

[0034] The invention and its embodiments have been described above illustratively. This description is not restrictive, and the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. The accompanying drawings are only one embodiment of the invention, and the actual structure is not limited thereto. No reference numerals in the claims should limit the scope of the claims. Therefore, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the spirit of the invention, such design should fall within the scope of protection of this patent. Furthermore, the word "comprising" does not exclude other elements or steps, and the word "a" preceding an element does not exclude the inclusion of "a plurality" of that element. Multiple elements stated in the product claims may also be implemented by a single element through software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any specific order.

Claims

1. A method for automatically adjusting the air direction at the outlet of a mine air curtain, characterized in that: Includes the following steps: (1) Install an air outlet regulating device (5) and an air curtain (1) in the roadway where airflow needs to be blocked, ejected, or increased. The air outlet regulating device is used to drive the air curtain to rotate horizontally. Install pressure sensors on both sides of the roadway where airflow needs to be blocked to measure the pressure difference ΔH1 between the two sides where airflow needs to be blocked. (2) Calculate the actual pressure ΔH2 generated by the mine air curtain at the point where airflow needs to be blocked in the roadway. ΔH2 ≈ k × (ρ × Q × v × cosθ) / A, where: △H2: isolation pressure difference, k: mine scene correction coefficient, ρ: air density, Q: air curtain air volume, v: outlet wind speed, θ: installation angle, A: airflow action cross-sectional area; (3) Using the PLC control system for comparison, when △H1≥(1.0-1.2)△H2, the PLC control system drives the outlet adjustment device to drive the air curtain to rotate towards the center line of the roadway until △H1 approaches (1.0-1.2)△H2; when △H1<(1.0-1.2)△H2, the PLC control system drives the outlet adjustment device to drive the air curtain to rotate towards the roadway side until △H1 approaches (1.0-1.2)△H2.

2. The method for automatically adjusting the air direction of the mine air curtain outlet as described in claim 1, characterized in that: The PLC control system has a human-computer interactive visual interface that can display the comparison results of △H1 and △H2.

3. The method for automatically adjusting the air direction of the mine air curtain outlet as described in claim 1, characterized in that: The air curtain (1) includes a mining axial flow fan (11) and a variable diameter diffuser (12).

4. The method for automatically adjusting the air direction of the mine air curtain outlet as described in claim 1, characterized in that: The PLC control system (2) is located in the ground dispatch center and is connected to the pressure sensor and the air outlet adjustment device.

5. The method for automatically adjusting the air direction of the mine air curtain outlet as described in claim 1, characterized in that: The pressure sensors are spaced 2m-3m apart and suspended at the intersection of the roadway centerline and waistline. The acquisition holes are aligned with the direction of airflow to measure the static pressure difference between the two sides.

6. The method for automatically adjusting the air direction of the mine air curtain outlet as described in claim 3, characterized in that: The air outlet adjustment device (5) includes a fixed frame (51), an installation plate (56) is installed inside one end of the fixed frame, a fixed base (52) is fixedly connected to the center of the installation plate, the top of the fixed base is rotatably connected to the mine axial flow fan through a rotating shaft (53), a movable arm (54) extends axially inside the fixed frame, the two ends of the movable arm are respectively installed plates and slidably connected to one end of the fixed frame, an electric telescopic rod (55) is fixedly connected to the outside of the fixed frame and is connected to the movable arm in a transmission connection, and the upper surface of the end of the movable arm away from the mine axial flow fan is fixedly connected to a variable diameter diffuser.

7. The method for automatically adjusting the air direction of the mine air curtain outlet as described in claim 1, characterized in that: The value of k is between 0.8 and 1.

2.

8. The method for automatically adjusting the air direction of the mine air curtain outlet as described in claim 1, characterized in that: The value of ρ is between 1.2 kg / m³ and 1.3 kg / m³.

9. The method for automatically adjusting the air direction of the mine air curtain outlet as described in claim 1, characterized in that: The value of Q is determined by the machine number.

10. The method for automatically adjusting the air direction of the mine air curtain outlet as described in claim 1, characterized in that: The value of A is approximately equal to the net cross-sectional area of ​​the tunnel.

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