Airflow measurement device in a pipe, airflow measurement method in a pipe

Abstract

To provide an air duct air flow measurement device and air duct air flow measurement method, which enable more accurate measurement of a gas flowing through an air duct temporarily installed in an upper space of a tunnel, and which can handle air ducts with different diameters.SOLUTION: An air duct air flow measurement device is provided, comprising a base body 10 installed inside an air duct 1, and multiple pitot tubes 20 used for gas pressure measurement, the base body 10 being arranged to extend vertically from one end to the other end of a diameter of the air duct 1 and having a rod-like measurement body mounting part 11 configured to have the multiple pitot tubes 20 attached thereto, where the measurement body mounting part 11 can be changed in length to suit the diameter of the air duct 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an airflow measurement device in an air duct and an airflow measurement method in an air duct, which perform measurement of gas flowing through a temporarily installed air duct in an upper space inside a mine pit.

Background Art

[0002] At tunnel construction sites, mining sites and the like, for the purpose of supplying air to the working face, a flexible or rigid air duct connected to a blower is temporarily installed in the upper space inside the mine pit. For this air duct, it is confirmed that ventilation meeting the regulations is performed by regularly checking the air volume and air velocity. In general, the air volume and air velocity are calculated based on the gas pressure measured by a worker inserting a pitot tube into the inside of the air duct. Here, Patent Document 1 discloses a flow rate measurement device in which a small tube is inserted into a main pipe through which a fluid flows, a throttling mechanism is provided in the small tube, a part of the flow in the main pipe is diverted into the small tube, and the differential pressure generated in the small tube is detected by a detector to measure the flow rate in the main pipe. Further, Patent Document 2 discloses a fluid pressure detection device in which a porous pitot tube is arranged such that the longitudinal direction thereof intersects the flow axis direction of the airflow in the air duct, the porous pitot tube is composed of a long sensor tube, a pressure output plug provided at one end of the sensor tube, and a sealing plug for sealing the other end of the sensor tube, and the porous pitot tube is attached to the air duct such that the sealing plug side penetrates the wall surface of the conduit of the air duct. Further, Patent Document 3 discloses a combination of a pitot tube or a porous tube and a flow straightening grid.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

[0004] Regular ventilation checks are performed not only at the outlet of the air duct but also at various points along its length. However, since air ducts often extend for several hundred meters or more, manually inserting a Pitot tube into each section of the duct to measure the pressure is time-consuming. Furthermore, manual measurements raise concerns about the reliability of the data. Additionally, air ducts come in various diameters, and requiring a corresponding measuring device for each diameter would increase costs. Here, the invention described in Patent Document 1 measures the fluid velocity using a small throttling mechanism instead of a Pitot tube, but it is difficult to apply to temporary air ducts installed in mine shafts. Furthermore, the inventions described in Patent Documents 2 and 3 cannot be addressed by using a single type of porous Pitot tube or the like for multiple air ducts with different diameters. Therefore, the present invention aims to provide an airflow measuring device and method for measuring airflow within a duct that can more accurately measure the gas flowing through a duct temporarily installed in the upper space of a mine shaft, and that can also accommodate ducts of different diameters. [Means for solving the problem]

[0005] The airflow measuring device inside a wind pipe according to claim 1 of the present invention is used in a wind pipe 1 temporarily installed in the upper space inside a mine. A wind tube airflow measuring device for measuring the flow of gas, comprising a base 1 installed inside the wind tube 1. The system comprises a 0 and a plurality of Pitot tubes 20 used for measuring the pressure of a gas, and the base 10 has a diameter of the air duct 1 A rod-shaped measuring device extending vertically from one end to the other, to which multiple Pitot tubes 20 are attached. It has an attachment part 11, and the length of the measuring body attachment part 11 can be changed to match the diameter of the air duct 1. The base 10 has a rectangular shape formed by combining one U-shaped frame 10A and the other U-shaped frame 10B in opposite directions, and is equipped with a frame connecting member 15 that slidably connects one U-shaped frame 10A and the other U-shaped frame 10B, and the length of the measuring body mounting portion 11 is changed by sliding either one U-shaped frame 10A or the other U-shaped frame 10B. It is characterized by the following: The present invention as described in claim 2 is characterized in that, in the airflow measuring device inside the air tube described in claim 1, the Pitot tube 20 is attached to the measuring body mounting portion 11 in a manner that allows the mounting position to be changed. The present invention as described in claim 3 is characterized in that, in the airflow measuring device inside the air duct as described in claim 1, it comprises a mounting device 50 for suspending the base body 10 from the suspension wire 3 that suspends the air duct 1. The present invention as described in claim 4 is an airflow measuring device inside a wind tube as described in claim 3, wherein the base body 10 has an upper frame 12 that is provided perpendicular to the measuring body mounting portion 11 from the upper end of the measuring body mounting portion 11, and the base body 10 is suspended from the suspension wire 3 by connecting the suspension wire 3 and the upper frame 12 via a mounting fixture 50. 。 Claim 5 The method for measuring airflow inside a wind tube according to the present invention, as described in claims 1 to 1. 4 The airflow measuring device base 10 described in any one of the above items is installed multiple times at predetermined intervals inside the air duct 1, and the pressure of the gas flowing through the air duct 1 is measured at multiple locations at the same time. [Effects of the Invention]

[0006] According to the present invention, it is possible to more accurately measure the gas flowing through a temporary air pipe installed in the upper space of a mine shaft, and it can also accommodate air pipes of different diameters. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows the state in which the airflow measuring device inside the air duct according to one embodiment of the present invention is installed. [Figure 2] Diagram showing the same substrate [Figure 3] This diagram shows the base and pitot tube placed inside the air duct. [Figure 4] This diagram shows the base suspended from the suspension wire. [Figure 5] Diagram showing a different form of mounting fixture. [Modes for carrying out the invention]

[0008] The airflow measurement device in an air duct according to the first embodiment of the present invention is an airflow measurement device in an air duct that measures gas flowing through a temporarily installed air duct in the upper space inside a mine, and includes a base body installed inside the air duct and a plurality of Pitot tubes used for gas pressure measurement. The base body has a rod-shaped measurement body mounting portion that extends vertically from one end to the other end of the diameter of the air duct and to which the plurality of Pitot tubes are attached, and the length of the measurement body mounting portion can be adjusted according to the diameter of the air duct. According to the present embodiment, since the base body to which the plurality of Pitot tubes are attached can be pre-installed inside the air duct, pressure measurement can be performed more accurately than in the case where Pitot tubes are manually inserted into the air duct. In addition, since the length of the measurement body mounting portion can be arbitrarily adjusted according to the diameter of the air duct, it can be adapted to various air ducts with different diameters.

[0009] In the airflow measurement device in an air duct according to the first embodiment, the second embodiment of the present invention is configured such that the Pitot tubes are attached to the measurement body mounting portion with their mounting positions changeable. According to the present embodiment, the Pitot tube for total pressure measurement can be easily aligned (height alignment) to the total pressure measurement position (height inside the air duct) specified for each diameter of the air duct.

[0010] In the airflow measurement device in an air duct according to the first embodiment, the third embodiment of the present invention is provided with a fixture for suspending the base body from a suspension wire that suspends the air duct. According to the present embodiment, by suspending the base body from the suspension wire instead of directly connecting it to the air duct, almost no weight of the base body is applied to the air duct, so deformation or damage of the air duct caused by the base body arranged inside can be effectively prevented.

[0011] In the airflow measurement device in an air duct according to the third embodiment, the fourth embodiment of the present invention is configured such that the base body has an upper frame provided perpendicularly to the measurement body mounting portion from the upper end of the measurement body mounting portion, and the base body is suspended from the suspension wire by connecting the suspension wire and the upper frame via the fixture. According to the present embodiment, swinging of the base body caused by wind pressure can be suppressed.

[0012] In the airflow measuring device in an air duct according to the first embodiment, the fifth embodiment of the present invention has a base body in a quadrangular shape formed by combining one U-shaped frame and the other U-shaped frame in opposite directions, and is provided with a frame connecting member that slidably connects the one U-shaped frame and the other U-shaped frame, wherein the length of the measuring body mounting portion is changed by sliding the one U-shaped frame or the other U-shaped frame. According to the present embodiment, the length of the measuring body mounting portion can be easily changed.

[0013] In the airflow measuring method in an air duct according to the sixth embodiment of the present invention, a plurality of base bodies of the airflow measuring device in an air duct according to any one of the first to fifth embodiments are installed at predetermined intervals inside the air duct, and the pressure of the gas flowing through the air duct is measured at a plurality of positions at the same time. According to the present embodiment, since the acquisition time of measurement data at each measurement point can be made simultaneous, it is possible to improve the prediction accuracy of the air volume, wind speed, and the like at the working face (air duct outlet) estimated from the data of the measurement points in the middle of the air duct.

Example

[0014] An airflow measuring device in an air duct and an airflow measuring method in an air duct according to an example of the present invention will be described. Figure 1 is a diagram showing a state where the airflow measuring device in an air duct according to the present example is installed. The air duct 1 is temporarily installed in the upper space inside the mine from the inlet to the working face during tunnel construction, mining work, and the like. The air duct 1 is formed by connecting, for example, about 200 flexible (soft) air duct bodies made of vinyl chloride resin or the like that expand into a cylindrical shape with a total length of 10000 mm and a diameter of 1800 mm. The air duct bodies may also be non-flexible (hard). The inlet side of the air duct 1 is connected to a blower, and gas (air) is sent to the outlet side (working face side) by the blower.

[0015] The airflow measuring device in the air tube comprises a rigid base 10, a plurality of L-shaped pitot tubes 20 attached to the base 10, a pressure-resistant hose 30 extending from the pitot tubes 20, and a measurement result display unit 40 to which the pressure-resistant hose 30 is connected. The base unit 10 and the pitot tube 20 are installed inside the air duct 1, and the measurement result display unit 40 is installed on the side of the tunnel. The pressure-resistant hose 30 is inserted into the air duct 1 through a hole in which a drain plug 2 is provided, with one end connected to the pitot tube 20 and the other end connected to the measurement result display unit 40. The measurement result display unit 40 displays data such as wind speed and airflow rate based on the total pressure and static pressure inside the air duct 1 measured by the Pitot tube 20. It is also possible to connect a PC or other device to the measurement result display unit 40 to import or transfer measurement data externally.

[0016] Figure 2 shows the base structure; Figure 2(a) shows one U-shaped frame combined with the other U-shaped frame, and Figure 2(b) shows one or the other U-shaped frame individually. The base 10 has a rectangular shape, formed by combining a pair of U-shaped frames, each made from a rod-shaped member with a larger diameter than the pitot tube 20 and shaped into a roughly U-shape, from the end side with the orientations reversed. It has a front frame 11, an upper frame 12 provided perpendicular to the front frame 11 from the upper end of the front frame 11, a lower frame 13 provided perpendicular to the front frame 11 from the lower end of the front frame 11, and a rear frame 14 provided parallel to the front frame 11. The U-shaped frames are made of, for example, stainless steel (SUS). The front frame 11 is the measuring body mounting section in this embodiment, and multiple Pitot tubes 20 are attached to it. One U-shaped frame 10A, which has an upper frame 12, and the other U-shaped frame 10B, which has a lower frame 13, are slidably connected by frame connecting members 15, one each provided on the front frame 11 and the rear frame 14. The frame connecting member 15 has a frame insertion portion 15A and a frame fastening portion 15B. The frame insertion portion 15A has two hollow short pipes arranged in parallel, the inner diameter of which is slightly larger than the outer diameter of the U-shaped frame. One end of one U-shaped frame 10A is inserted through one hollow short pipe, and one end of the other U-shaped frame 10B is inserted in the opposite direction through the other hollow short pipe. The frame fastening portion 15B is, for example, a wing bolt and nut that are passed through a hole provided on the side of the hollow short pipe. By tightening the wing bolt and bringing the tip of the bolt into contact with the U-shaped frame, the U-shaped frame can be fastened so that it does not slide. The length of the measuring body mounting section 11 can be changed by loosening the wing bolt of the frame fastening section 15B, moving the bolt tip away from the U-shaped frame, and sliding one U-shaped frame 10A or the other U-shaped frame 10B to change the distance between the upper frame 12 and the lower frame 13, i.e., the length of the base body 10.

[0017] Figure 3 shows the base and pitot tube placed inside the air duct; Figure 3(a) is a side view, and Figure 3(b) is a front view. The base 10 is positioned so as not to create resistance to the flowing gas, with its width parallel to the axis of the air duct 1. When the base 10 is installed inside the air duct 1, the upper frame 12 is in contact with the upper inner surface of the air duct 1, the lower frame 13 is in contact with the lower inner surface of the air duct 1, and the front frame 11 is located upstream of the rear frame 14. As described above, the length of the measuring body mounting section (front frame) 11 can be arbitrarily changed to match the diameter of the air duct 1 by sliding the U-shaped frame, thus accommodating various air ducts 1 with different diameters. The length of the measuring body mounting section (front frame) 11 can be adjusted, for example, from a minimum of 1000 mm to a maximum of 3000 mm. The measuring body mounting section (front frame) 11 and the rear frame 14 are adjusted so that their length is approximately the same as the diameter of the air duct 1, and they extend vertically from the upper inner surface to the lower inner surface, intersecting the central axis of the air duct 1.

[0018] The front frame 11, which is a measuring body mounting section to which multiple pitot tubes 20 are attached, has five pitot tubes 20 for total pressure measurement and one pitot tube 20 for static pressure measurement mounted vertically at predetermined intervals. The five pitot tubes 20 for total pressure measurement are each positioned at a specified location (height inside the air duct), with their tips facing upstream. By pre-installing the base 10 with multiple pitot tubes 20 attached inside the air duct 1 in this manner, pressure measurements can be performed more accurately compared to manually inserting the pitot tubes 20 into the air duct 1. The L-shaped pitot tube 20 is secured to the front frame 11 via bolts and nuts, etc., so that its mounting position on the front frame 11 can be arbitrarily changed. Because the mounting position on the front frame 11 can be changed, not only the length of the front frame (measuring body mounting section) 11 but also the height of the pitot tube 20 inside the air duct can be changed according to the diameter of the air duct 1. Therefore, the pitot tube 20 for measuring total pressure can be easily positioned (height adjusted) to the total pressure measurement position specified for each diameter of the air duct 1.

[0019] Figure 4 shows the base unit suspended from the suspension wire. The air duct 1 is suspended from a suspension wire 3, such as a messenger wire, which is stretched across the upper surface of the tunnel, via multiple air duct suspension fittings 4. The airflow measuring device inside the air duct is suspended from the suspension wire 3 by a mounting fixture 50. The mounting fixture 50 is, for example, a set of suspension fittings. The mounting fixture 50 is installed by penetrating the upper surface of the air duct 1, with one end connected to the suspension wire 3 and the other end connected to the upper frame 12 of the base 10. By suspending the base 10 from the suspension wire 3 instead of directly connecting it to the air duct 1, the weight of the base 10 is hardly placed on the air duct 1, effectively preventing deformation or damage to the air duct 1 caused by the base 10 being placed inside. Furthermore, by suspending the base 10 from the suspension wire 3 by connecting the suspension wire 3 and the upper frame 12 via the mounting fixture 50, the upper frame 12, which is in contact with the upper inner surface of the air duct 1, acts as resistance, suppressing the oscillation of the base 10 due to wind pressure. In addition, while the measurement positions (measurement points) for total pressure in an annular air duct 1 (round duct) are set at multiple locations concentrically from the center point, by suspending the base 10 from the suspension wire 3, the measurement body mounting part 11 naturally becomes located at the center in the width direction of the air duct 1 regardless of sagging or expansion of the air duct 1, allowing the Pitot tube 20 to be easily and accurately positioned at the specified measurement position for total pressure.

[0020] Figure 5 shows another form of mounting fixture; Figure 5(a) is an illustrative diagram of the combined mounting fixture, Figure 5(b) is a side view showing the connection to the suspension wire, and Figure 5(c) is a front cross-sectional view showing the connection to the suspension wire. The mounting fixture 50 in this embodiment includes a pair of upper parts 51 positioned on the upper outer surface of the air duct 1, a lower part 52 positioned on the upper inner surface of the air duct 1, an upper and lower part connecting member 53 such as a bolt connecting the upper parts 51 and the lower parts 52, a hanger 54 having an annular portion and attached to the upper part 51, and a hanging fitting 55 such as a carabiner connecting the suspension wire 3 and the hanger 54. In addition, a hole is provided on the upper surface of the air duct 1 for passing the upper and lower part connecting member through. The pair of upper parts 51 consist of a first upper part 51A positioned on one of the air duct suspension parts 5 provided on the upper outer surface of the air duct 1, and a second upper part 51B positioned on the other. The first upper part 51A and the second upper part 51B are provided with one hole each at the front and rear for passing the upper and lower part connecting member 53. The lower part 52 has a recess in the center in the width direction for receiving the upper frame 12, and there is one hole on the front and one on the rear for passing the upper and lower part connecting material 53 through. When suspending the base 10 from the suspension wire 3, the upper part 51 is placed on the upper outer surface of the air duct 1, and the lower part 52 is placed on the upper inner surface of the air duct 1, and the two are connected by an upper and lower part connecting member 53. In addition, a hanging handle 54 is attached to the front upper and lower part connecting member 53, and the hanging handle 54 and the suspension wire 3 are connected by a suspension fitting 55. According to the mounting device 50 of this embodiment, the state in which the base 10 is suspended from the suspension wire 3 can be stably maintained for a relatively long period of time.

[0021] In a method for measuring airflow inside a duct using an airflow measuring device, it is preferable to install multiple base units 10 with Pitot tubes 20 attached at predetermined intervals inside the duct 1, and to simultaneously measure the pressure of the gas flowing through the duct 1 at multiple locations at the same time. Conventionally, workers have to go around to each measurement point to measure total pressure and static pressure, resulting in differences in the time it takes to acquire measurement data for each measurement point. However, with the airflow measurement method inside the air duct of the present invention, the time it takes to acquire measurement data at each measurement point can be simultaneous, thus improving the accuracy of predictions of airflow volume and wind speed at the face (air duct outlet) estimated from data at measurement points along the air duct 1. Furthermore, compared to the case where workers insert the Pitot tube 20 into the air duct 1 each time a measurement is taken, the measurement becomes more accurate, the reliability of the data is increased, and the burden on the workers is reduced. [Explanation of Symbols]

[0022] 1 windpipe 3 Hanging wire 10 Base 10A One U-shaped frame 10B The other U-shaped frame 11. Mounting section for measuring body 12. Upper frame 15 Frame connecting material 20 Pitot tubes 50 Mounting hardware

Claims

1. A device for measuring the airflow within a temporary air pipe installed in the upper space inside a mine shaft, A base installed inside the aforementioned air duct, The system comprises a plurality of Pitot tubes used for measuring the pressure of the aforementioned gas, The base has a rod-shaped measuring body mounting portion that extends vertically from one end to the other of the diameter of the air duct and to which a plurality of the Pitot tubes are attached, and the length of the measuring body mounting portion can be changed to match the diameter of the air duct. The base is rectangular in shape, formed by combining one U-shaped frame and the other U-shaped frame in opposite directions, and includes a frame connecting member that slidably connects the one U-shaped frame and the other U-shaped frame. The airflow measuring device inside a wind tube is characterized in that the length of the measuring body mounting portion is changed by sliding one of the U-shaped frames or the other U-shaped frame.

2. The airflow measuring device in a wind tube according to claim 1, characterized in that the Pitot tube is attached to the measuring body mounting portion so that its mounting position can be changed.

3. The airflow measuring device inside an air duct according to claim 1, further comprising a mounting device for suspending the base body from a suspension wire that suspends the air duct.

4. The base has an upper frame that is provided perpendicular to the measuring body mounting portion from the upper end of the measuring body mounting portion, The airflow measuring device in a wind tube according to claim 3, characterized in that the base body is suspended from the suspension wire by connecting the suspension wire and the upper frame via the mounting fixture.

5. A method for measuring airflow inside a duct, characterized by installing multiple bases of the airflow measuring device described in any one of claims 1 to 4 inside a duct at predetermined intervals, and measuring the pressure of the gas flowing through the duct at multiple locations at the same time.

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