A kind of wind speed probe based on spindle throttle and pipeline air volume measurement method

Abstract

The present application belongs to the technical field of flow measurement, and discloses a wind speed probe based on spindle throttling and a pipeline air volume measurement method. The wind speed probe comprises a spindle throttling head, a measuring rod, a high-pressure pressure-taking pipe, a low-pressure pressure-taking pipe, a static pressure-taking pipe and a temperature sensor. The spindle is installed in the throttling head cylinder to form an annular flow channel, the high-pressure pressure-taking hole is located at the front edge section of the spindle, and the low-pressure pressure-taking hole is located at the middle section of the annular flow channel. The cross section of the measuring rod is bullet-shaped, and a short tail wing is arranged at the tail portion. The present application measures the axial wind speed by adopting the spindle throttling principle, the annular flow channel has a flow regulating effect, and the multi-point pressure-taking pressure equalizing design is combined to effectively reduce the flow deflection and vortex influence; the pressure-taking holes are located on the inner wall of the cylinder, and are not easy to block; the probe integrates the static pressure and temperature measurement. By measuring the differential pressure, the static pressure and the temperature, the flow rate and the air volume are calculated in combination with the calibration coefficient, and the present application is suitable for the accurate measurement of large-diameter, low-flow-rate and dust-containing flue gas pipelines.

Description

Technical Field

[0001] This invention belongs to the field of flow measurement technology, and particularly relates to a wind speed probe based on spindle throttling and a method for measuring air volume in pipelines. Background Technology

[0002] Accurate measurement of airflow from industrial chimneys and flues is crucial for environmental monitoring and carbon emission measurement. Flue gas flow measurement is technically challenging due to the large pipe diameter, short straight pipe sections, low flow velocity, and the presence of contaminated particles and moisture in the medium.

[0003] Commonly used flue gas flow meters include differential pressure flow meters, ultrasonic flow meters, and thermal flow meters. Differential pressure flow measurement methods are further divided into single-point Pitot tubes and multi-point averaging pitot tubes, both based on the velocity-area method. The Pitot tube measures the velocity at only one point, resulting in a larger measurement error compared to the averaging pitot tube. Both types are prone to clogging when the particulate matter concentration in the flue is high. Furthermore, both Pitot tubes and averaging pitot tubes are dynamic pressure type; when the flue gas velocity is low, the differential pressure is small, leading to a large measurement error, and turbulence-induced measurement errors are also significant. Thermal flow meters offer advantages such as high accuracy and large measurement range, but their response speed is relatively slow, and their measurement accuracy is affected by temperature, humidity, and pressure. Ultrasonic flow meters are characterized by stable operation and high accuracy, but their disadvantages include a limitation on flue gas temperatures and a higher price.

[0004] In summary, differential pressure flow meters, represented by Pitot tubes and averaging pitot tubes, are still widely used in the field of flue gas flow measurement. The main problems at present are that they are prone to clogging and have poor resistance to the influence of turbulence (the measurement error is large when turbulence is present). Summary of the Invention

[0005] The purpose of this invention is to provide a wind speed probe based on spindle throttling and a method for measuring air volume in pipelines, so as to solve the above-mentioned technical problems.

[0006] To solve the above-mentioned technical problems, the specific technical solution of the present invention, which is a wind speed probe based on spindle throttling and a method for measuring air volume in pipelines, is as follows:

[0007] A wind speed probe based on a spindle-shaped throttling device includes: a spindle-shaped throttling head, a measuring rod, a high-pressure tapping tube, a low-pressure tapping tube, a static pressure tapping tube, and a temperature sensor. The spindle-shaped throttling head comprises a throttling head cylinder and a spindle body, the spindle body being installed inside the throttling head cylinder and forming an annular flow channel between the spindle body and the throttling head cylinder. The high-pressure tapping hole is located on the throttling head cylinder and communicates upstream of the annular flow channel. The low-pressure tapping hole is located on the throttling head cylinder and communicates with the annular flow channel. The measuring rod is connected to the spindle-shaped throttling head and contains the high-pressure tapping tube, the low-pressure tapping tube, the static pressure tapping tube, and the temperature sensor. The high-pressure tapping tube communicates with the high-pressure tapping hole, and the low-pressure tapping tube communicates with the low-pressure tapping hole. The static pressure tapping tube and the temperature sensor are used to measure the static pressure and temperature of the fluid in the pipeline.

[0008] Furthermore, the spindle body includes a head, a middle section, and a tail. The head is a rotating paraboloid or a rotating ellipsoid, the middle section is a cylinder, and the tail is a converging frustum shape.

[0009] Furthermore, there are multiple high-pressure taps, which are evenly distributed along the circumference of the throttling head cylinder, and their positions correspond to the cross-section where the leading edge of the spindle body is located.

[0010] Furthermore, a rectangular groove is formed on the outer wall of the high-pressure tapping section of the throttling head cylinder. Two 180° "U"-shaped pressure equalization chamber cover plates are embedded in the groove on the outer wall of the throttling head cylinder to form a pressure tapping ring chamber. A pressure tapping hole is formed above the pressure equalization chamber cover plate. The pressure tapping hole is connected to the pressure tapping ring chamber. The high-pressure tapping hole is connected to the throttling head cylinder and the pressure tapping ring chamber.

[0011] Furthermore, the low-pressure tap is located at the middle section of the annular flow channel.

[0012] Furthermore, the cross-section of the measuring rod is bullet-shaped, the windward side is bullet-shaped, and short tail fins are provided on both sides of the tail on the leeward side.

[0013] Furthermore, the measuring rod is provided with static pressure holes on both sides for measuring the static pressure of the fluid in the pipeline, and the static pressure tapping pipe is connected to the static pressure holes.

[0014] Furthermore, it also includes a connecting flange, which is provided with a directional arrow to indicate the inlet direction of the spindle body throttling head.

[0015] Furthermore, it also includes:

[0016] A differential pressure transmitter, connected to a high-pressure tap and a low-pressure tap, is used to measure differential pressure.

[0017] A pressure transmitter, connected to a static pressure tap, is used to measure static pressure;

[0018] A temperature transmitter, connected to a temperature sensor, is used to measure the temperature of a fluid.

[0019] This invention also discloses a method for measuring air volume based on spindle throttling, comprising the following steps:

[0020] The wind speed probe is installed inside the pipe with its axis parallel to the pipe axis; the differential pressure Δp before and after the throttling head is obtained through high-pressure and low-pressure taps; the static pressure p and temperature t of the fluid inside the pipe are obtained through static pressure taps and a temperature sensor; the fluid density ρ is determined based on the fluid medium, static pressure, and temperature; and the axial velocity v at the location of the spindle-shaped throttling head is calculated.

[0021] Calculate the air volume based on the flow velocity v and the duct cross-sectional area A. .

[0022] The anemometer and duct airflow measurement method based on spindle throttling of the present invention have the following advantages:

[0023] (1) The axial wind speed at a point on the pipe cross section is measured using a spindle body throttling principle wind speed probe, and the flow rate is obtained based on the velocity area method. The annular flow channel between the spindle body and the inner wall of the throttling head cylinder has a flow straightening effect. Combined with the average pressure of 4 holes taken from the high pressure tapping section of the spindle body throttling head, these two designs can effectively reduce the influence of flow deviation and vortex on the measurement and ensure the accuracy of axial velocity measurement.

[0024] (2) The high-pressure and low-pressure taps of the spindle body throttling head are both on the inner wall of the throttling head cylinder, not directly facing the incoming flow, and are not easily blocked.

[0025] (3) The cross-section of the measuring rod is bullet-shaped, and the outer side plate on the leeward side extends backward with a short-stroke wing. The vortex street formed by the measuring rod is small in size and intensity, has little interference with the flow, and the vortex-induced vibration of the measuring rod is relatively small.

[0026] (4) The wind speed probe integrates static pressure tapping and fluid temperature measurement functions. It has a high degree of integration and is convenient for simultaneous measurement of flow rate, pressure and temperature. It is easy to install and use. Attached Figure Description

[0027] Figure 1 A schematic diagram of a wind speed probe based on spindle throttling;

[0028] Figure 2 This is a schematic diagram of the wind speed probe rod structure;

[0029] Figure 3 This is a schematic diagram of the wind speed probe pipeline installation.

[0030] Figure 4 A schematic diagram of the arrangement of three wind speed probes combined at 120° for measurement;

[0031] Figure 5 A schematic diagram of a 90° combination measurement setup for three wind speed probes;

[0032] The markings in the diagram are as follows: 1. Spindle body throttling head; 2. Measuring rod; 3. High-pressure tapping pipe; 4. Low-pressure tapping pipe; 5. Connecting flange; 6. Static pressure tapping pipe; 7. Temperature sensor; 11. Throttling head cylinder; 12. Equalizing chamber cover plate; 13. Spindle body; 14. Support plate; 21. Short tail fin; 22. Static pressure hole; 51. Marking arrow; 101. Pipe; 102. Probe tube seat; 103. Differential pressure transmitter; 104. Pressure transmitter; 105. Temperature transmitter; 111. High-pressure tapping hole; 112. Low-pressure tapping hole; 121. Pressure tapping ring chamber; 122. Pressure tapping hole; 131. Annular flow channel. Detailed Implementation

[0033] To better understand the purpose, structure, and function of this invention, the following description, in conjunction with the accompanying drawings, provides a more detailed account of a wind speed probe based on spindle throttling and a method for measuring air volume in a pipeline.

[0034] Figure 1 This is a schematic diagram of a wind speed probe based on a spindle-shaped throttling device. As shown, the wind speed probe includes a spindle-shaped throttling head 1, a measuring rod 2, a high-pressure tapping pipe 3, a low-pressure tapping pipe 4, a connecting flange 5, a static pressure tapping pipe 6, and a temperature sensor 7. The spindle-shaped throttling head 1 includes a throttling head cylinder 11, a pressure equalization chamber cover plate 12, a spindle body 13, and a support plate 14. The leading edge of the throttling head cylinder 11 has an arc-shaped inlet, and the spindle body 13 is installed inside the throttling head cylinder 11 at a rearward position. The two are welded together by the support plate 14. The spindle body 13 can be divided into three parts: a head, a middle section, and a tail section. The head is a rotating paraboloid or a rotating ellipsoid, the middle section is a cylinder, and the tail section is a converging frustum shape. An annular flow channel 131 is formed between the spindle body 13 and the throttling head cylinder 11. The throttling head cylinder 11 has four high-pressure tapping holes 111, located on the cross-section corresponding to the leading edge of the spindle body 13, and evenly distributed along the circumference. A rectangular groove is formed on the outer wall of the high-pressure tapping section of the throttling head cylinder 11. Two 180° U-shaped pressure equalization chamber cover plates 12 are embedded in the groove on the outer wall of the throttling head cylinder 11, forming a pressure-tapping ring chamber 121. A pressure tapping hole 122 is formed above the pressure equalization chamber cover plate 12. The pressure tapping hole 122 communicates with the pressure-tapping ring chamber 121. The high-pressure tapping hole 111 communicates with both the throttling head cylinder 11 and the pressure-tapping ring chamber 121. The low-pressure tapping hole 112 of the throttling head cylinder 11 is located at the middle cross-section of the annular flow channel 131 and communicates with the annular flow channel 131.

[0035] Figure 2The structure of measuring rod 2 is shown. Measuring rod 2 is a cylindrical column with a bullet-shaped cross-section. The windward side is bullet-shaped to reduce wind pressure. Short tail fins 21 extend from both sides of the leeward side. This design weakens the intensity of Karman vortex street shedding and reduces vortex size, thus reducing vortex-induced vibration of the measuring rod and anemometer. Two static pressure holes 22 are opened on each side of measuring rod 2 to measure the pressure flowing inside the tube. Measuring rod 2 is fully welded to the spindle-shaped throttling head 1 and the connecting flange 5 to ensure a tight seal. The inlet of the spindle-shaped throttling head 1 is aligned with the bullet-shaped end of measuring rod 2. The connecting flange 5 has an arrow 51 indicating the inlet direction of the spindle-shaped throttling head 1, aligned with the bullet-shaped end.

[0036] High-pressure tapping pipe 3 and low-pressure tapping pipe 4 are inserted into measuring rod 2 via connecting flange 5. Their bottoms are connected to pressure tapping holes 122 (and subsequently high-pressure tapping hole 111) and 112 of the spindle-shaped throttling head 1, respectively. High-pressure tapping pipe 3 and low-pressure tapping pipe 4 are used to measure the high and low pressures of the throttling head cylinder 11, respectively. Static pressure tapping pipe 6 and temperature sensor 7 are inserted into measuring rod 2 via connecting flange 5. Static pressure tapping pipe 6 is connected to static pressure hole 22 and is used to measure the static pressure of the fluid in the pipe. Temperature sensor 7 is used to measure the temperature of the fluid in the pipe. Figure 3 As shown, the high-pressure tap 3 and the low-pressure tap 4 are connected to the differential pressure transmitter 103. The differential pressure transmitter 103 is used to measure the pressure data of the high-pressure tap 3 and the low-pressure tap 4 and to calculate the pressure difference. The static pressure tap 6 is connected to the pressure transmitter 104. The pressure transmitter 104 is used to measure the pressure data of the static pressure tap 6. The temperature sensor 7 is connected to the temperature transmitter 105. The temperature transmitter 105 is used to read the data from the temperature sensor 7 and to calculate the fluid temperature in the pipeline.

[0037] When in use, a single anemometer or a combination of multiple anemometers can be used to measure the air volume inside the duct. Figure 3 The installation configuration for a single anemometer probe during airflow measurement is shown. The anemometer probe is fixedly mounted on the probe holder 102 of pipe 101 via connecting flange 5. The axis of the spindle-shaped throttling head 1 is parallel to the axis of pipe 101, and the directional arrow 51 on connecting flange 5 points directly towards the inflow direction of the pipe (see [reference]). Figure 2 ).

[0038] During measurement, differential pressure transmitter 103 reads the differential pressure Δp from the spindle body throttling velocity probe, pressure transmitter 104 reads the static pressure p of the fluid inside the pipe, and temperature transmitter 105 measures and reads the temperature t of the fluid inside the pipe. Given a specific fluid medium, the density can be determined based on the pressure and temperature. The axial velocity v at the location of the spindle body throttling head is:

[0039]

[0040] In the formula, C vρ is the flow velocity coefficient, determined through experimental calibration; Δp is the differential pressure between the high-pressure and low-pressure taps; ρ is the fluid density, determined based on the type of fluid medium being measured, the measured pressure, and the temperature; β is the equivalent diameter ratio, calculated by the following formula:

[0041]

[0042] Where d is the inner diameter of the throttling head cylinder 11; d s The diameter of the straight section of the spindle body 12.

[0043] Figure 3 The spindle-shaped throttling head 1 is placed at the center of the pipe. The flow velocity measured here is the maximum flow velocity within the pipe cross-section, which has a certain relationship with the average flow velocity of the pipe. Assuming the average flow velocity v... a =C q According to the velocity-area method, the volumetric flow rate (or air volume) in the pipe is:

[0044]

[0045] Among them, C q The flow coefficient is related to the position of the wind speed probe in the measurement section. If the spindle throttling head 1 is located at the average velocity point of the section, then C q =1; A is the pipe flow area.

[0046] In practical use, multiple wind speed probes can be combined for measurement to improve measurement accuracy. Figure 4 This diagram illustrates the arrangement of three wind speed probes. Probes F1, F2, and F3 are evenly placed circumferentially at 120° intervals. The radial positions r1, r2, and r3 of the spindle-shaped throttling head are located at the average velocity points (A1=A2=A3) of the central circle, middle ring, and outer ring, respectively. The arithmetic mean of the velocities measured by the three probes is the cross-sectional average velocity. When calculating the air volume, the average velocity value is substituted into C. q =1.

[0047] Considering the ease of on-site pipe opening and installation, the three wind speed probes can be installed at a 90° angle. (See attached image.) Figure 5 The average flow velocity remains the arithmetic mean of the three probes, and the duct airflow calculation is also consistent with... Figure 4 The situation is the same.

[0048] The foregoing has shown and described the basic structure, working principle, and main features of the wind speed probe of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the basic structure and principle of the present invention. Various changes and modifications can be made without departing from the spirit and scope of the present invention, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A wind speed probe based on spindle throttling, characterized in that, include: The device comprises a spindle-shaped throttling head (1), a measuring rod (2), a high-pressure tapping tube (3), a low-pressure tapping tube (4), a static pressure tapping tube (6), and a temperature sensor (7). The spindle-shaped throttling head (1) includes a throttling head cylinder (11) and a spindle body (13). The spindle body (13) is installed inside the throttling head cylinder (11) and forms an annular flow channel (131) with the throttling head cylinder (11). The high-pressure tapping hole (111) is opened on the throttling head cylinder (11) and communicates upstream of the annular flow channel (131). The low-pressure tapping hole (111) is located on the throttling head cylinder (11) and communicates upstream of the annular flow channel (131). A pressure hole (112) is opened on the throttling head cylinder (11) and communicates with the annular flow channel (131); the measuring rod (2) is connected to the spindle throttling head (1), and its interior is provided with a high pressure tapping pipe (3), a low pressure tapping pipe (4), a static pressure tapping pipe (6) and a temperature sensor (7); the high pressure tapping pipe (3) is communicated with the high pressure tapping hole (111), the low pressure tapping pipe (4) is communicated with the low pressure tapping hole (112), and the static pressure tapping pipe (6) and the temperature sensor (7) are used to measure the static pressure and temperature of the fluid in the pipeline.

2. The wind speed probe based on spindle throttling according to claim 1, characterized in that, The spindle body (13) includes a head, a middle part and a tail. The head is a rotating parabola or a rotating ellipsoid, the middle part is a cylinder and the tail is a contracted frustum shape.

3. The wind speed probe based on spindle throttling according to claim 1, characterized in that, The high-pressure tapping holes (111) are multiple and are evenly distributed along the circumference of the throttling head cylinder (11), with their positions corresponding to the cross section where the leading edge of the spindle body (13) is located.

4. The wind speed probe based on spindle throttling according to claim 3, characterized in that, The high-pressure tapping section of the throttling head cylinder (11) has a rectangular groove on its outer wall. Two 180° "U"-shaped pressure equalization chamber cover plates (12) are embedded in the groove on the outer wall of the throttling head cylinder (11) to form a pressure tapping ring chamber (121). A pressure tapping hole (122) is opened above the pressure equalization chamber cover plate (12). The pressure tapping hole (122) is connected to the pressure tapping ring chamber (121). The high-pressure tapping hole (111) is connected to the throttling head cylinder (11) and the pressure tapping ring chamber (121).

5. The wind speed probe based on spindle throttling according to claim 1, characterized in that, The low-pressure tap (112) is located at the middle section of the annular flow channel (131).

6. The wind speed probe based on spindle throttling according to claim 1, characterized in that, The cross-section of the measuring rod (2) is bullet-shaped, the windward side is bullet-shaped, and short tail fins (21) are provided on both sides of the tail on the leeward side.

7. The wind speed probe based on spindle throttling according to claim 1, characterized in that, The measuring rod (2) has static pressure holes (22) on both sides for measuring the static pressure of the fluid in the pipe. The static pressure tapping pipe (6) is connected to the static pressure holes (22).

8. The wind speed probe based on spindle throttling according to claim 1, characterized in that, It also includes a connecting flange (5), which has a directional arrow (51) to indicate the inlet direction of the spindle body throttling head (1).

9. The wind speed probe based on spindle throttling according to claim 1, characterized in that, Also includes: A differential pressure transmitter (103) is connected to a high-pressure tap (3) and a low-pressure tap (4) for measuring differential pressure. A pressure transmitter (104) is connected to a static pressure tap (6) for measuring static pressure; A temperature transmitter (105) is connected to a temperature sensor (7) for measuring fluid temperature.

10. A method for measuring air volume based on spindle throttling, characterized in that, Includes the following steps: The wind speed probe as described in any one of claims 1-9 is installed inside the pipe, with its axis parallel to the pipe axis. The differential pressure Δp before and after the throttling head is obtained through the high-pressure tapping pipe (3) and the low-pressure tapping pipe (4); The static pressure p and temperature t of the fluid in the pipe are obtained by using a static pressure tap (6) and a temperature sensor (7); Determine the fluid density ρ based on the fluid medium, static pressure, and temperature; calculate the axial velocity at the location of the spindle body throttling head. v , According to flow rate v Calculate the air volume based on the cross-sectional area A of the pipe. .

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