A device and method for measuring dust-laden air flow velocity and concentration

Abstract

The invention discloses a device and method for measuring the velocity and concentration of a dust-laden airflow. The device comprises an airfoil plate, a connecting rod, a first sensor, and a second sensor housing. One end of the connecting rod is rigidly connected to the airfoil plate, and the other end is connected to the first sensor and the second sensor in sequence. The first sensor and the second sensor are torque sensors or tension / pressure sensors. The relative position of the housing and a pipeline is fixed, and the other sides of the first sensor and the second sensor are connected to the housing. The first sensor and the second sensor are connected to the input end of a calculation unit, and the output end of the calculation unit is connected to an output module. Force or torque is used as a measurement signal instead of a pressure difference signal, and signal distortion or loss will not be caused by the presence of dust. The structure of the connection between the airfoil plate and the sensor is not affected by the monitoring direction, and can be applied to vertically arranged pipelines or horizontally arranged pipelines. Torque sensors and tension / pressure sensors are cheaper and more reliable than pressure sensors.

Description

Technical Field

[0001] The invention belongs to the field of dust-laden airflow measurement, and in particular relates to a device and a method for measuring the velocity and concentration of dust-laden airflow. Background Art

[0002] Gas-solid two-phase flow is unstable and non-uniform, and accurate measurement of its velocity and concentration has always been a technical challenge in this field. Some scholars have conducted research based on pressure difference method, thermal balance method, electrical method, ultrasonic method, etc., but mature and reliable measurement products have not yet been formed.

[0003] By achieving accurate online measurement of the velocity and concentration of dust-laden airflow, we can grasp the actual parameters of equipment operation, making the unknown visible, and provide effective data support for equipment operation parameter monitoring and refined and intelligent operation optimization and adjustment. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a device and method for measuring the velocity and concentration of dust-laden air flow, so as to realize monitoring of the velocity and concentration of dust-laden air flow, such as the velocity of air flow and the concentration of pulverized coal in a pulverized coal boiler in a power station.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a device for measuring the velocity and concentration of dust-laden airflow, comprising an airfoil, a connecting rod, a first sensor, and a second sensor housing; one end of the connecting rod is rigidly connected to the airfoil, and the other end is connected to the first sensor and the second sensor in sequence, the first sensor is a tension / pressure sensor, and the second sensor is a torque sensor, the relative position of the housing and the pipeline is fixed, and the other sides of the first sensor and the second sensor are connected to the housing; the force directions of the first sensor and the second sensor are 90°, the first sensor and the second sensor are connected to the input end of the calculation unit, and the output end of the calculation unit is connected to the output module.

[0006] The specific shape and size of the airfoil.

[0007] A plurality of identical airfoil panels form an airfoil panel group, each airfoil panel is arranged in the same direction, and the plurality of airfoil panels are connected to the connecting rod via the same connecting plate.

[0008] The airfoil panels are arranged vertically or horizontally.

[0009] The output module includes a communication unit, which is used to send the signal output by the calculation unit to a remote control center or a handheld terminal; the calculation unit is arranged on the housing or the remote control center.

[0010] The airfoil is arranged parallel to the pipeline axis or at a set angle.

[0011] The wing plate is welded and fixed to the connecting rod, the connecting rod is led out through an opening on the pipe wall, and a flexible sealing layer is arranged between the connecting rod and the opening on the pipe wall; the outer shell is arranged on the pipe bracket, the outer wall of the pipe or an independent foundation.

[0012] The wing plates and connecting rods are made of wear-resistant materials.

[0013] It also includes a connecting pipe, in which the wing plate is arranged. The connecting pipe has a through hole, one end of the connecting rod extends into the connecting pipe and passes through the through hole to connect the wing plate, a flexible sealing layer is arranged between the connecting rod and the through hole, and the shape and cross-section of the connecting pipe are respectively the same as the shape and cross-section of the pipe section to be tested.

[0014] A method for measuring the velocity and concentration of dust-laden air flow comprises the following steps:

[0015] When one or a group of airfoils are placed in a dusty airflow, the airfoils will be subject to two forces in the airflow: the lift F1 generated by the airflow velocity and the thrust F2 generated by the airflow on the airfoil. When the angle between the airfoil and the airflow direction is constant, the relationship between the lift F1 and the thrust F2 and the airflow velocity v and the dust concentration μ is as follows:

[0016]

[0017]

[0018] K1, K2, m and n are the coefficients of the lift and thrust on the airfoil and the airflow velocity and dust concentration;

[0019] The first sensor and the second sensor measure the lift F1 and thrust F2 on the airfoil; K1, K2, m and n are determined by theoretical calculation and experiment;

[0020] The average velocity and dust concentration of the dust-laden airflow are obtained according to the lift F1 and the thrust F2; and the average velocity and dust concentration are output.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] The first sensor and the second sensor collect the lift and thrust exerted on the airfoil; the first sensor and the second sensor use force or torque as measurement signals instead of pressure difference signals, and will not cause signal distortion or loss due to the presence of dust; there are no rotating or moving parts and it is easy to seal; the structure of the connection between the airfoil and the sensor of the present invention is not affected by the monitoring direction and can be applied to vertically arranged pipes or horizontally arranged pipes; torque sensors and tension pressure sensors are cheaper than pressure sensors and have higher reliability.

[0023] Furthermore, the use of multiple airfoil panels can increase the measured values ​​of lift and thrust, while improving the correlation between the measured values ​​and the average velocity of the cross section, and the average value of the entire cross section can be measured to ensure the representativeness of the measured values.

[0024] Furthermore, the computing unit disposed on the housing can also realize local monitoring, and the data does not need to be transmitted over long distances; arranging the computing unit in a remote control center is conducive to timely grasping each monitoring data. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a schematic diagram of an implementable structure of the present invention.

[0026] In the accompanying drawings, 1-airfoil, 2-connecting rod, 3-first sensor, 4-computing unit, 5-output module, 6-housing, 7-second sensor. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to specific embodiments and accompanying drawings.

[0028] In the flowing airflow, due to the pressure difference caused by the speed difference of the airflow on the upper and lower surfaces, the airfoil will be subject to a lift, which can generally be calculated by the following formula:

[0029]

[0030] ρ airflow density, v relative speed between airfoil and airflow, C s is the lift coefficient, A is the projected area of ​​the airfoil, and C is the lift coefficient. s It is related to the shape of the airfoil and the angle between the airfoil and the airflow. For a specific airfoil, when the angle between the airfoil and the airflow is constant, the above formula can be simplified as:

[0031]

[0032] At the same time, the airfoil will also receive thrust from the flowing airflow, which can generally be calculated using the following formula:

[0033]

[0034] C d is the drag coefficient, the area of ​​the S-shaped airfoil in the airflow direction. Similarly, for a specific airfoil, when the angle between the airfoil and the airflow is constant, the above formula can be simplified as:

[0035]

[0036] When the airfoil is placed in a flowing dusty airflow, the force on the airfoil is similar to that in a pure airflow state, but the presence of particles has a certain influence on the force.

[0037] Under the action of airflow, the airfoil is still affected by two forces. The lift F1 generated by the airfoil is related to the airflow velocity v, the dust concentration μ and the angle between the airfoil and the airflow (angle of attack). When the angle of attack is a fixed angle, F1 is only related to the airflow velocity and dust concentration. The test shows that the lift can be calculated using the following formula:

[0038]

[0039] The airfoil in the dusty airflow is also subject to the thrust F2 of the airflow and dust particles. Similarly, when the angle of attack is a fixed angle, F2 is related to the airflow velocity and dust concentration. Tests show that the thrust can be calculated using the following formula:

[0040]

[0041] The four coefficients K1, K2, m, and n can all be obtained through theoretical calculations and test data, thereby determining the relationship between these two forces and air flow velocity and dust concentration.

[0042] When applied to the actual dust-laden pipe to measure the velocity and dust concentration of the dust-laden airflow, F1 and F2 are measured by a torque sensor or a push-pull force sensor. By combining equations (5) and (6), the airflow velocity and dust concentration at the measuring section can be calculated, thereby realizing the measurement of the airflow velocity and dust concentration.

[0043] According to the principle, the present invention provides a device for measuring the velocity and concentration of dust-laden airflow, comprising an airfoil 1, a connecting rod 2, a first sensor 3, a second sensor 7 and a housing 6; one end of the connecting rod 2 is rigidly connected to the airfoil 1, and the other end is connected to the first sensor 3 and the second sensor 7 in sequence, the first sensor 3 is a tension / pressure sensor, and the second sensor 7 is a torque sensor, the relative position of the housing 6 and the pipeline is fixed, and the other side of the first sensor 3 and the second sensor 7 are connected to the housing 6; the forces on the first sensor 3 and the second sensor are 90°, and the force direction of the first sensor 3 is along the airflow direction, the first sensor 3 and the second sensor 7 are connected to the input end of the calculation unit 4, and the output end of the calculation unit 4 is connected to the output module 5.

[0044] The computing unit 4 is arranged on a housing 6 or in a remote control center.

[0045] The airfoil plate 1 and the connecting rod 2 are welded and fixed.

[0046] The housing 6 is arranged on a pipeline support, an outer wall of the pipeline or an independent foundation.

[0047] The output module 5 includes a communication unit, which is used to send the signal output by the calculation unit 4 to a remote control center or a handheld terminal.

[0048] An implementable device of the present invention is as follows Figure 1 As shown, combined Figure 1 The technical solution of the present invention is further described:

[0049] The present invention provides a device, comprising an airfoil 1, a connecting rod 2, a sensor 3, a computing unit 4, a signal output module 5, and a housing 6. The airfoil or airfoil group 1 is installed in a dust-containing airflow to be measured. One end of the connecting rod 2 is rigidly connected to the airfoil 1, and the other end is connected to a first sensor 3 and a second sensor 7 in sequence. The other sides of the first sensor 3 and the second sensor 7 are fixed to the housing 6 arranged on the outer wall of a pipeline. The signal outputs of the first sensor 3 and the second sensor 7 are connected to the computing unit 4. The computing unit 4 can load calculation formulas (5) and (6). The computing unit connects the calculation results to the signal output module 5 to form output signals of airflow velocity and dust concentration.

[0050] Optionally, the wing plate 1 arranged in the dust-laden air flow duct to be measured can be set as a single wing-shaped element, or can be set as a wing plate group composed of multiple identical wing plates 1; when multiple wing plates are used, the wing plates are arranged in parallel, that is, the arrangement direction of each wing plate 1 is the same, and the wing plates are connected to form a wing plate group by a connecting member, for example, the connecting member is a connecting plate, and the wing plate 1 and the connecting rod 2 are welded and fixed to the connecting plate; using multiple wing plates can increase the measured values ​​of lift and thrust, and at the same time improve the correlation between the measured values ​​and the average velocity of the cross-section. Through reasonable layout and design, the average velocity of the entire cross-section can be measured to ensure the representativeness of the measured values.

[0051] Of course, the airfoil plate 1 and the pipeline axis can also be arranged in parallel or at a preset angle; when the airfoil plate 1 and the pipeline axis are arranged in parallel or at a set angle, an angle coefficient is introduced into the calculation formula.

[0052] The first sensor 3 and the second sensor 7 are arranged in a housing 6 outside the pipeline. The housing 6 is a closed cavity fixed on the pipeline. Only part of the housing is shown in the figure. The sensor 4 can be a torque sensor or a tension and pressure sensor. Figure 1 As shown, a torque sensor is used as an example. The connecting rod 2 transmits the force of the airfoil 1 to the sensor to measure the lift and thrust of the airfoil.

[0053] The connecting rod 2 is led out through an opening on the wall of the pipeline, and a flexible sealing layer is arranged between the connecting rod 2 and the opening on the wall of the pipeline.

[0054] As a preferred embodiment, the airfoil plate 1, connecting rod 2 and other components exposed to dust are made of wear-resistant materials.

[0055] In the pipeline to be measured, the airfoil plate 1 can be arranged vertically or horizontally, and the lift and thrust can be measured in a suitable direction, which can achieve effective measurement of air flow velocity and dust concentration.

[0056] The device can be applied to vertical or horizontal circular or rectangular pipes, and is not limited to Figure 1 The horizontal circular pipe shown in .

[0057] Since the lift of the airfoil 1 is greatly affected by the angle of attack, there are high requirements for the direction of the airflow to be measured, that is, it is hoped that the velocity direction of the airflow to be measured in the measuring section is consistent with the pipeline axis, that is, a longer straight pipe section is required before the measuring section; in the specific implementation application, the distance between the airfoil 1 and the pipe fitting is at least 2.5 times the radius of the pipeline.

[0058] The dust should be non-adhesive to avoid dust adhering to the airfoil, which will cause the airfoil to change and affect the lift and thrust values, causing measurement distortion. Because dust is abrasive, airfoil, connecting rods and other components exposed to dust need to be made of wear-resistant materials.

[0059] As an optional embodiment, the device for measuring the velocity and concentration of dust-laden air flow described in the present invention may also be provided with a connecting pipe, in which the wing plate 1 is arranged, and a through hole is opened in the connecting pipe, and one end of the connecting rod 2 extends into the connecting pipe and passes through the through hole to connect the wing plate 1, and the shape and cross-section of the connecting pipe are respectively the same as the shape and cross-section of the pipe section where the dust-laden air flow to be measured is located; a shell 6 is fixedly provided on the outer wall of the connecting pipe; to adapt to the shape of the pipe section where the dust-laden air flow to be measured is located, the connecting pipe may be circular or rectangular.

[0060] It is preferably used in dusty air flow pipes with a diameter of 200 to 1000 mm, such as the powder delivery pipes of pulverized coal boilers in power stations.

[0061] Based on the above, the present invention provides a method for measuring the velocity and concentration of dust-laden air flow, comprising the following steps:

[0062] When one or a group of airfoil panels 1 are placed in a dusty airflow, the airfoil panel 1 will be subjected to two forces in the airflow, namely, the lift F1 generated by the airflow velocity and the thrust F2 generated by the airflow on the airfoil panel 1. When the angle between the airfoil panel 1 and the airflow direction is constant, the relationship between the lift F1 and the thrust F2 and the airflow velocity v and the dust concentration μ is as follows:

[0063]

[0064]

[0065] K1, K2, m and n are the coefficients of relationship between the lift and thrust of the airfoil 1 and the airflow velocity and dust concentration;

[0066] The first sensor 3 and the second sensor 7 measure the lift F1 and thrust F2 on the airfoil; K1, K2, m and n are determined by theoretical calculation and experiment;

[0067] The average velocity and dust concentration of the dust-laden airflow are obtained according to the lift F1 and the thrust F2; and the average velocity and dust concentration are output.

Claims

1. A device for measuring the velocity and concentration of dust-laden airflow, characterized in that: The invention comprises an airfoil plate (1), a connecting rod (2), a first sensor (3), a second sensor (7) and a housing (6); one end of the connecting rod (2) is rigidly connected to the airfoil plate (1), and the other end is connected to the first sensor (3) and the second sensor (7) in sequence, the first sensor (3) is a tension / pressure sensor, and the second sensor (7) is a torque sensor; the relative position of the housing (6) and the pipeline remains fixed, and the other sides of the first sensor (3) and the second sensor (7) are connected to the housing (6); the force directions of the first sensor (3) and the second sensor (7) are 90°, the first sensor (3) and the second sensor (7) are connected to the input end of the calculation unit (4), and the output end of the calculation unit (4) is connected to the output module (5); when measuring the velocity and concentration of the dust-laden airflow, the invention comprises the following steps: When one or a group of airfoils (1) are placed in a dusty airflow, the airfoils (1) will be subjected to two forces in the airflow, namely, the lift F1 generated by the airflow velocity and the thrust F2 generated by the airflow on the airfoils (1). When the angle between the airfoils (1) and the airflow direction is constant, the lift F1 and the thrust F2 are related to the airflow velocity v and the dust concentration μ as follows: K1, K2, m and n are the coefficients of relationship between the lift and thrust of the airfoil (1) and the airflow velocity and dust concentration; The first sensor (3) and the second sensor (7) measure the lift F1 and thrust F2 exerted on the airfoil; K1, K2, m and n are determined by theoretical calculation and experiment; The average velocity and dust concentration of the dust-laden airflow are obtained according to the lift F1 and the thrust F2; and the average velocity and dust concentration are output.

2. The device for measuring the velocity and concentration of dust-laden air flow according to claim 1, characterized in that: A plurality of identical wing panels (1) form an wing panel group, each wing panel (1) is arranged in the same direction, and the plurality of wing panels (1) are connected to the connecting rod (2) via the same connecting plate.

3. The device for measuring the velocity and concentration of dust-laden air flow according to claim 1 or 2, characterized in that: The airfoil plate (1) is arranged vertically or horizontally.

4. The device for measuring the velocity and concentration of dust-laden air flow according to claim 1, characterized in that: The output module (5) comprises a communication unit, which is used to send the signal output by the calculation unit (4) to a remote control center or a handheld terminal; the calculation unit (4) is arranged on the housing (6) or the remote control center.

5. The device for measuring the velocity and concentration of dust-laden air flow according to claim 1, characterized in that: The wing plate (1) is arranged parallel to the pipeline axis or at a set angle.

6. The device for measuring the velocity and concentration of dust-laden air flow according to claim 1, characterized in that: The wing plate (1) is welded and fixed to the connecting rod (2), the connecting rod (2) is led out through an opening on the pipe wall, and a flexible sealing layer is arranged between the connecting rod (2) and the opening on the pipe wall; the outer shell (6) is arranged on a pipe bracket, an outer wall of the pipe or an independent foundation.

7. The device for measuring the velocity and concentration of dust-laden air flow according to claim 1, characterized in that: The wing plate (1) and the connecting rod (2) are made of wear-resistant materials.

8. The device for measuring the velocity and concentration of dust-laden air flow according to claim 1, characterized in that: It also includes a connecting pipe, the wing plate (1) is arranged in the connecting pipe, a through hole is provided in the connecting pipe, one end of the connecting rod (2) extends into the connecting pipe and passes through the through hole to connect the wing plate (1), a flexible sealing layer is arranged between the connecting rod (2) and the through hole, and the shape and cross section of the connecting pipe are respectively the same as the shape and cross section of the pipe section to be measured.

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