Flow velocity detection system and flue gas flow velocity detection method

Abstract

The invention relates to the technical field of fluid pressure detection, in particular to a flow velocity detection system and a flue gas flow velocity detection method. In the flow velocity detection system, a wind shielding side plate of a pitot tube is installed on a wind shielding bottom plate in a surrounding mode, and a wind gathering cavity is defined by the wind shielding side plate and the wind shielding bottom plate; a total pressure detection hole is formed in the wind shielding side plate, and a first air outlet and a second air outlet are symmetrically formed in the two sides of the total pressure detection hole in the wind shielding side plate; the inner surface of the area, where the first exhaust outlet and the second exhaust outlet are located, of the air blocking side plate is gradually shrunk in the direction towards the first exhaust outlet, the second exhaust outlet and the total pressure detection hole, and a closing-in structure is formed; one end of the total pressure transmission pipe is communicated with the total pressure detection hole, and the other end is communicated with the high-pressure end of the differential pressure sensor; the static pressure transmission pipe is arranged on the side, away from the windshield side plate, of the windshield bottom plate, a static pressure detection hole is formed in the end, close to the windshield bottom plate, of the static pressure transmission pipe, and the other end communicates with the low-pressure end of the differential pressure sensor. The pitot tube achieves physical blocking prevention and can normally work in a low-flow-speed flue containing a large number of particulate matter.

Description

Technical Field

[0001] The present application relates to the technical field of fluid pressure and fluid flow rate measurement, and in particular to a flow rate detection system and a flue gas flow rate detection method. Background Art

[0002] A Pitot tube, also known as a pitot tube or anemometer, is a tubular device that measures the total and static pressure of an airflow to determine air velocity. Pitot tubes are widely used in aerospace, ventilation ducts, environmental monitoring, wind power generation, thermal power generation, steel, and cement industries.

[0003] In the thermal power industry, pulverized coal pipelines or chimneys often contain large amounts of pulverized coal and other particulate matter. To ensure the normal operation of system equipment, real-time monitoring of the operating status of the pulverized coal pipeline and chimney is necessary. Using traditional Pitot tubes for monitoring is prone to blockage, resulting in inaccurate or even impossible measurements. Furthermore, the flow rate within pulverized coal pipelines or chimneys is low. Using traditional Pitot tubes for monitoring, the pressure difference between the total pressure and the static pressure that can be sensed is small, limiting the detectable flow rate range and resulting in insufficient sensitivity, making it unsuitable for detecting flow rates below 5 m / s. Therefore, traditional Pitot tubes are not suitable for measuring low-flow flues containing large amounts of particulate matter. Summary of the Invention

[0004] In order to overcome the problems existing in the related technology, the present application provides a flow rate detection system and a flue gas flow rate detection method. The flow rate detection system improves the structure of the traditional Pitot tube so that it has a physical anti-blocking function and can work normally in flues with low flow rates and containing a large amount of particulate matter.

[0005] According to an embodiment of the present application, a flow rate detection system is provided, including: a Pitot tube and a differential pressure sensor.

[0006] The Pitot tube includes: a windshield base plate; a windshield side plate, which is enclosed and installed on the windshield base plate and forms a wind gathering cavity with the windshield base plate; a total pressure detection hole is provided on the windshield side plate, and a first air outlet and a second air outlet are symmetrically provided on both sides of the total pressure detection hole on the windshield side plate; the area of the windshield side plate where the first air outlet and the second air outlet are located gradually shrinks in the direction toward the first air outlet, the second air outlet and the total pressure detection hole to form a closing structure; a total pressure transmission pipe, one end of the total pressure transmission pipe is connected to the total pressure detection hole, and the other end is connected to the high-pressure end of the differential pressure sensor; a static pressure transmission pipe, the static pressure transmission pipe is arranged on the side of the windshield base plate away from the windshield side plate, and the static pressure detection hole is provided on one end of the static pressure transmission pipe close to the windshield base plate, and the other end is connected to the low-pressure end of the differential pressure sensor.

[0007] In an alternative embodiment, the wind deflector side plate is formed by connecting multiple enclosing plates. The wind deflector side plate includes a first enclosing plate, and second and third enclosing plates symmetrically arranged on both sides of the first enclosing plate. The inner angles between the first enclosing plate and the second enclosing plate, and between the first enclosing plate and the third enclosing plate are greater than 90° and less than 120°; the total pressure detection hole is arranged on the first enclosing plate, the first air outlet is arranged on the second enclosing plate, and the second air outlet is arranged on the third enclosing plate.

[0008] In an alternative embodiment, the inner angle between the wind deflector side plate and the wind deflector bottom plate is greater than or equal to 90° and less than or equal to 120°.

[0009] In an alternative embodiment, an anti-blowing assembly is further included. The anti-blowing assembly includes a first switching valve, a total pressure anti-blowing pipe, and an anti-blowing air source; the first switching valve has a first air vent, a second air vent, and a third air vent, and the first switching valve can act to connect the first air vent to one of the second air vent and the third air vent; the total pressure transfer pipe is connected to the first air vent, one end of the total pressure anti-blowing pipe is connected to the second air vent, and the high-pressure end of the differential pressure sensor is connected to the third air vent; the other end of the total pressure anti-blowing pipe is connected to the anti-blowing air source.

[0010] In an alternative embodiment, the anti-blowing assembly further includes a second switching valve and a static pressure anti-blowing pipe; the second switching valve has a fourth air vent, a fifth air vent, and a sixth air vent, and the second switching valve can act to connect the fourth air vent to one of the fifth air vent and the sixth air vent; the static pressure transfer pipe is connected to the fourth air vent, one end of the static pressure anti-blowing pipe is connected to the fifth air vent, and the low-pressure end of the differential pressure sensor is connected to the sixth air vent; the other end of the static pressure anti-blowing pipe is connected to the anti-blowing air source.

[0011] In an alternative embodiment, the anti-blowing air source includes an anti-blowing compressed air tank and an air compressor. The air compressor is connected to the anti-blowing compressed air tank, and the anti-blowing compressed air tank is connected to the other end of the total pressure anti-blowing pipe.

[0012] According to the embodiments of the present application, a flue gas flow velocity detection method is further provided. Using the flow velocity detection system described in the above embodiments, the method includes the following steps:

[0013] Obtain the calibration coefficient of the pitot tube, and the calibration coefficient is obtained through wind tunnel testing;

[0014] Insert the pitot tube into the flue, make the opening of the wind gathering cavity face the direction of flue gas inflow, and the wind deflector bottom plate is perpendicular to the direction of flue gas inflow;

[0015] Obtain the pressure difference between the total pressure detection hole and the static pressure detection hole of the Pitot tube sensed by the differential pressure sensor;

[0016] Calculate the flue gas flow velocity according to the calibration coefficient of the Pitot tube and the pressure difference:

[0017] , where is the fluid velocity, is the calibration coefficient of the Pitot tube, is the fluid density, is the total pressure measured at the total pressure detection port, is the static pressure measured at the static pressure detection port.

[0018] In the technical solution of the embodiment of the present application, by improving the structure of the traditional Pitot tube and setting a wind-accumulating cavity that can convert the fluid flow direction and increase the fluid flow velocity, the Pitot tube and the flow velocity detection system have a physical anti-blocking function and can work normally in a flue with a lower flow velocity and containing a large amount of particulate matter.

[0019] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application.

[0020] For better understanding and implementation, the present application will be described in detail below with reference to the accompanying drawings. Description of the Drawings

[0021] Figure 1 is a schematic structural diagram of the flow velocity detection system provided by the embodiment of the present application.

[0022] Figure 2 is a schematic structural diagram of the Pitot tube provided by the embodiment of the present application.

[0023] Figure 3 is a schematic structural diagram of the backwashing assembly provided by the embodiment of the present application.

[0024] Reference Numerals in the Drawings: 1, Pitot tube; 11, wind-blocking bottom plate; 12, wind-blocking side plate; 121, first enclosing plate; 122, second enclosing plate; 123, third enclosing plate; 124, first air outlet; 125, second air outlet; 126, auxiliary enclosing plate; 13, total pressure transfer pipe; 14, static pressure transfer pipe; 15, total pressure detection hole; 16, static pressure detection hole; A, wind-accumulating cavity; 2, differential pressure sensor; 31, first switching valve; 311, first ventilation port; 312, second ventilation port; 313, third ventilation port; 32, total pressure backwashing pipe; 331, backwashing compressed air tank; 332, air compressor; 34, second switching valve; 341, fourth ventilation port; 342, fifth ventilation port; 343, sixth ventilation port; 35, static pressure backwashing pipe. Detailed Embodiments

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. Components of the embodiments of this application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of this application that is claimed, but merely represents selected embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts fall within the scope of protection of this application.

[0027] In application scenarios of flue gas ducts containing a large amount of particulate matter, such as in the thermal power industry, steel industry, cement industry, etc., measuring the fluid flow velocity in the flue gas duct is an extremely important part, which is related to the stability and safety of the overall operation of the system equipment. The technical solution of this embodiment is described by taking the application scenario of a low-flow flue gas duct containing a large amount of particulate matter in the thermal power industry as an example, but the scope of protection is not limited to the thermal power industry and is equally applicable to other fields in which low-flow fluids containing a large amount of particulate matter are detected.

[0028] Traditional pitot tubes are S-type pitot tubes or L-type pitot tubes. The total pressure detection hole of the traditional pitot tube directly faces the fluid flow direction. If there are particulate matters in the fluid, it is easy to directly blow into the total pressure detection hole and cause blockage, resulting in the inability to measure or inaccurate measurement. In addition, in application scenarios of low-flow flue gas ducts, such as when the flue gas flow velocity is below 5 m / s, the pressure difference between the total pressure and static pressure sensed by the traditional pitot tube is small, resulting in a limited detected flow velocity range. If it is forcibly applied to the detection of lower-flow fluids, there will be problems such as insufficient sensitivity and large measurement errors.

[0029] Based on this, this application provides a pitot tube and a flow velocity detection system. The pitot tube has a physical anti-blocking function, can increase the fluid flow velocity to change the pressure at the total pressure detection hole, can sense lower flow velocities, and can work normally in low-flow flue gas ducts containing a large amount of particulate matter.

[0030] As Figure 1 shown, the flow velocity detection system includes a pitot tube 1 and a differential pressure sensor 2; the pitot tube 1 is used to transmit the total pressure and static pressure of the fluid flow velocity; the differential pressure sensor 2 is used to sense the pressure difference between the total pressure and static pressure of the fluid flow velocity.

[0031] Combined Figure 2 、 Figure 3 viewed, the pitot tube 1 includes: a windscreen bottom plate 11, a windscreen side plate 12, a total pressure transfer tube 13, and a static pressure transfer tube 14.

[0032] The windshield side panel 12 is installed in an enclosed manner on the windshield bottom plate 11, and forms an air gathering chamber A together with the windshield bottom plate 11; a total pressure detection hole 15 is provided in the middle position of the windshield side panel 12, and the windshield side panel 12 is symmetrically provided with a first air outlet 124 and a second air outlet 125 on both sides of the total pressure detection hole 15; the inner surface of the windshield side panel area where the first air outlet 124 and the second air outlet 125 are located gradually shrinks in the direction toward the first air outlet 124, the second air outlet 125 and the total pressure detection hole 15 to form a closing structure, and when observed from the angle facing the total pressure detection hole 15, the closing structure is funnel-shaped.

[0033] One end of the total pressure transmission pipe 13 is connected to the total pressure detection hole 15 , and the other end is connected to the high-pressure end of the differential pressure sensor 2 .

[0034] Static pressure transmission pipe 14 is located on the side of windshield base plate 11 facing away from windshield side plate 12. A static pressure detection hole 16 is provided at one end of static pressure transmission pipe 14, which is closest to windshield base plate 11. The other end of static pressure transmission pipe 14 is connected to the low-pressure terminal of differential pressure sensor 2. Structurally, static pressure detection hole 16 avoids the flow of flue gas from first and second exhaust ports 124, 125, thereby better sensing static pressure.

[0035] The present pitot tube 1 is used to detect flow velocity in a flue containing particulate matter. When in use, the opening of the air collecting chamber A of the pitot tube 1 is oriented toward the direction of flue gas inflow. The windshield side plate 12 of the air collecting chamber A blocks particulate matter in the flue gas and causes it to fall. The closing structure of the air collecting chamber A accelerates the flue gas and guides it to the first and second exhaust ports 124 and 125 for discharge. At this time, the accelerated flue gas enters the total pressure detection hole 15 of the pitot tube 1, flows through the total pressure transmission pipe 13, and enters the high-pressure end of the differential pressure sensor 2, realizing the detection of the total pressure of the fluid. At the same time, the static pressure detection hole 16 located away from the windshield side plate 12 avoids fluid interference from the exhaust port and only senses the static pressure, allowing the low-pressure end of the differential pressure sensor 2 to sense the static pressure of the fluid. Finally, the fluid flow rate can be calculated based on the pressure difference between the total pressure of the fluid and the static pressure of the fluid and the calibration coefficient of the pitot tube, thereby realizing flue gas detection of low-flow fluid containing a large amount of particulate matter without clogging the pitot tube 1.

[0036] The technical solution of this embodiment improves the structure of the traditional Pitot tube 1 to prevent the total pressure detection hole 15 from being directly opposite the incoming flow direction, so that the Pitot tube 1 has a physical anti-blocking function, can increase the fluid flow rate, and thus change the pressure at the total pressure detection hole 15, can sense lower flow rates, and can work normally in flues with low flow rates and containing a large amount of particulate matter.

[0037] The ability to increase the fluid velocity in the flue is related to the calibration coefficient of the pitot tube, and the calibration coefficient of the pitot tube is related to the structural design of the pitot tube 1. In order to obtain the corresponding fluid velocity increase ability, in a preferred embodiment, the windward side plate 12 is formed by connecting multiple enclosing plates. The windward side plate 12 includes a first enclosing plate 121, and second enclosing plates 122 and third enclosing plates 123 symmetrically arranged on both sides of the first enclosing plate 121. The total pressure detection hole 15 is arranged on the first enclosing plate 121 and is located in the central area of the first enclosing plate 121; the first air outlet 124 is arranged on the second enclosing plate 122 and is located in the central area of the second enclosing plate 122; the second air outlet 125 is arranged on the third enclosing plate 123 and is located in the central area of the third enclosing plate 123. The inner angle between the first enclosing plate 121 and the second enclosing plate 122 is greater than 90° and less than 120°. Within this angle range, the larger the inner angle between the first enclosing plate 121 and the second enclosing plate 122, the stronger the fluid velocity increase ability, and the larger the calibration coefficient of the pitot tube; the inner angle between the first enclosing plate 121 and the third enclosing plate 123 is greater than 90° and less than 120°. Within this angle range, the larger the inner angle between the first enclosing plate 121 and the third enclosing plate 123, the stronger the fluid velocity increase ability, and the larger the calibration coefficient of the pitot tube. With the structural design of this pitot tube 1, the flue gas velocity in the wind gathering cavity A is increased by about more than 2 times, and it can be applied to the measurement of fluid velocity below 3 m / s.

[0038] Optionally, when the inner angles between the first enclosing plate 121 and the second enclosing plate 122 and between the first enclosing plate 121 and the third enclosing plate 123 are both determined, the smaller the aperture of the first air outlet, the larger the calibration coefficient of the pitot tube, and the smaller the aperture of the second air outlet, the larger the calibration coefficient of the pitot tube.

[0039] Optionally, to better achieve the wind gathering effect and increase the total pressure that the total pressure detection hole 15 can sense, the inner angle between the windward side plate 12 and the windward bottom plate 11 is greater than or equal to 90° and less than or equal to 120°.

[0040] Optionally, the windward side plate 12 further includes auxiliary enclosing plates 126 connected to the second enclosing plates 122 and the third enclosing plates 123. The auxiliary enclosing plates 126 can be formed by splicing multiple enclosing plates with each other, or be an arc-shaped enclosing plate. The auxiliary enclosing plates 126, the second enclosing plates 122, the third enclosing plates 123, and the first enclosing plate 121 enclose to form the wind gathering cavity A, and the shape of the windward bottom plate 11 is adapted to the cross-sectional shape of the wind gathering cavity A.

[0041] In other embodiments, the second enclosing plates 122, the third enclosing plates 123, and the auxiliary enclosing plates 126 can all be arc-shaped. The inner surfaces of the second enclosing plates 122 and the third enclosing plates 123 gradually contract along the direction towards the first air outlet 124, the second air outlet 125, and the total pressure detection hole 15 to form a closed-end structure to achieve the wind gathering effect.

[0042] Using the pitot tube 1 improved by this structure, the fluid direction can be changed to prevent particulate matter in the flue gas from entering the total pressure detection hole 15, and the wind speed can be increased by a corresponding multiple, so that the pitot tube 1 can be applied to the detection of flue gas with a lower flow rate. Compared with the traditional pitot tube 1, the lower limit of wind speed measurement of the improved pitot tube 1 can reach 3 m / s, and the lower limit of flow rate measurement is increased by 40%.

[0043] In order to remove the blockage on the pipeline of the total pressure transfer pipe 13, further improve the anti-blocking ability and detection accuracy of the flow rate detection system, the flow rate detection system is also provided with a backflush component, that is, the total pressure detection pipeline and the static pressure detection pipeline are purged by a backflush gas source to avoid soot accumulation.

[0044] As Figure 3 shown, in the specific structural design, the backflush component includes a first switching valve 31, a total pressure backflush pipe 32 and a backflush gas source; the first switching valve 31 has a first ventilation port 311, a second ventilation port 312 and a third ventilation port 313, and the first switching valve 31 can act to connect the first ventilation port 311 with one of the second ventilation port 312 or the third ventilation port 313; the total pressure transfer pipe 13 is connected to the first ventilation port 311, one end of the total pressure backflush pipe 32 is connected to the second ventilation port 312, and the high-pressure end of the differential pressure sensor 2 is connected to the third ventilation port 313; the other end of the total pressure backflush pipe 32 is connected to the backflush gas source.

[0045] During the application process, when measuring the total pressure through the differential pressure sensor 2, control the first switching valve 31 to act so that the first ventilation port 311 is connected to the third ventilation port 313; when purging the total pressure transfer pipeline through the backflush gas source, control the first switching valve 31 to act so that the first ventilation port 311 is connected to the second ventilation port 312. In this way, the backflush gas source reaches the second ventilation port 312 of the first switching valve 31 through the total pressure backflush pipe 32, then flows out from the first ventilation port 311, and blows towards the air gathering cavity A of the pitot tube 1 through the total pressure transfer pipe 13.

[0046] Optionally, in order to realize the purging of the static pressure detection pipeline, further improve the anti-blocking ability and detection accuracy of the flow rate detection system, the backflush component further includes a second switching valve 34 and a static pressure backflush pipe 35; the second switching valve 34 has a fourth ventilation port 341, a fifth ventilation port 342 and a sixth ventilation port 343, and the second switching valve 34 can act to connect the fourth ventilation port 341 with one of the fifth ventilation port 342 or the sixth ventilation port 343; the static pressure transfer pipe 14 is connected to the fourth ventilation port 341, one end of the static pressure backflush pipe 35 is connected to the fifth ventilation port 342, and the low-pressure end of the differential pressure sensor 2 is connected to the sixth ventilation port 343; the other end of the static pressure backflush pipe 35 is connected to the backflush gas source.

[0047] During the application process, when measuring the static pressure through the differential pressure sensor 2, the second switching valve 34 is controlled to act, so that the fourth vent port 341 is communicated with the sixth vent port 343; when purging the static pressure transfer pipe 14 through the backflush gas source, the second switching valve 34 is controlled to act, so that the fourth vent port 341 is communicated with the fifth vent port 342. In this way, the backflush gas source reaches the fifth vent port 342 of the second switching valve 34 through the static pressure backflush pipe 35, then flows out from the fourth vent port 341, and blows towards the air collecting cavity A of the pitot tube 1 through the static pressure transfer pipe 14.

[0048] Optionally, the backflush gas source includes a backflush compressed air tank 331 and an air compressor 332. The air compressor 332 is connected to the backflush compressed air tank 331, and the backflush compressed air tank 331 is communicated with the other end of the total pressure backflush pipe 32. The setting of the air compressor 332 can improve the power of the backflush gas source and better achieve the purging effect.

[0049] The technical solution of this embodiment improves the structure of the traditional pitot tube, avoids the total pressure detection hole directly facing the oncoming flow direction, enables the pitot tube to have a physical anti-blocking function, and can increase the fluid velocity so as to change the pressure at the total pressure detection hole, can sense lower flow velocities, and can work normally in a flue with low flow velocities and a large amount of particulate matter. Compared with the traditional pitot tube, the lower limit of the wind speed measurement of the improved pitot tube can reach 3 m / s, and the lower limit of the flow velocity measurement is increased by 40%.

[0050] Furthermore, the flow velocity detection system can also purge the detection pipeline through the backflush assembly, avoid the accumulation of soot on the pitot tube and the detection pipeline, thus better realizing the anti-blocking function and improving the detection accuracy of low fluid flow velocities.

[0051] Based on the flow velocity detection system provided in the above embodiment, the present application embodiment also provides a flue gas flow velocity detection method.

[0052] The flue gas flow velocity detection method includes the following steps:

[0053] S1: Obtain the calibration coefficient of the pitot tube, and the calibration coefficient is obtained through wind tunnel testing;

[0054] S2: Insert the pitot tube into the flue, make the opening of the air collecting cavity face the direction of the flue gas inflow, and the wind shielding bottom plate is perpendicular to the direction of the flue gas inflow;

[0055] S3: Obtain the pressure difference between the total pressure detection hole and the static pressure detection hole of the pitot tube sensed by the differential pressure sensor;

[0056] S4: Calculate the flue gas flow velocity according to the pitot tube calibration coefficient and the pressure difference:

[0057] , where is the fluid velocity, is the calibration coefficient of the Pitot tube, is the fluid density, is the total pressure measured at the total pressure detection port, is the static pressure measured at the static pressure detection port.

[0058] When using the Pitot tube of the above embodiment to measure the flue gas flow rate, according to the Bernoulli equation of ideal incompressible gas, the sum of the kinetic energy, potential energy, and pressure energy of a unit fluid is a constant, which can be expressed by Formula 1: , where is the fluid density; is the acceleration due to gravity; is the pressure energy of the fluid; is the fluid velocity; is the total energy of a unit fluid. When the gravitational potential energy remains unchanged, the sum of the kinetic energy and pressure energy of the fluid is also a constant. When the Pitot tube is measuring, the height difference can be ignored, meeting the condition of unchanged gravitational potential energy.

[0059] The total pressure measured at the total pressure detection port is , and the static pressure measured at the static pressure detection port is , and according to the Bernoulli equation, Formula 2 is obtained: .

[0060] The calibration coefficient of the Pitot tube with improved structure is , and the specific value is obtained through wind tunnel testing. Substituting the calibration coefficient of the Pitot tube into Formula 2, Formula 3 can be transformed: , thereby calculating the flue gas flow rate.

[0061] In the technical solution of this embodiment, when measuring the fluid flow rate of the flue gas pipeline or chimney in the thermal power industry through the improved Pitot tube and the flow rate detection system, the flue gas blows towards the air gathering cavity of the Pitot tube. The wind shielding side plate of the air gathering cavity blocks the flue gas and the particulate matter therein, avoiding the direct blowing of the flue gas to the total pressure detection hole. The particulate matter falls freely, and after the flow direction of the flue gas is changed, it is blown out from the air outlet. At the same time, due to the converging structure of the air gathering cavity, the wind speed increases, and the fluid pressure entering the total pressure detection port increases, so that the Pitot tube can be applied to the detection of lower fluid flow rates.

[0062] Furthermore, the flow rate detection system can also purge the detection pipeline through the backflush component, avoiding the accumulation of soot on the Pitot tube and the detection pipeline, thereby better realizing the anti-blocking function and improving the detection accuracy of the fluid flow rate.

[0063] In the description of the embodiments of the present application, it should be noted that if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use. This is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. In addition, in the description of the present application, if terms such as "first", "second", etc. are used only for distinguishing descriptions, they cannot be understood as indicating or implying relative importance. In addition, in the description of the present application, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging vertically, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0064] In the description of the present application, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0065] The terms used in the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "the", and "said" used in the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0066] Note that the above is only the preferred embodiment of the present application and the technical principles applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein. Various obvious changes, re-adjustments, and substitutions can be made by those skilled in the art without departing from the protection scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments. Without departing from the concept of the present application, more other equivalent embodiments can be included, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A flow velocity detection system, characterized in that, include: Pitot tubes and differential pressure sensors; The pitot tube comprises: Windshield bottom plate; A windshield side panel, wherein the windshield side panel is mounted on the windshield bottom panel and forms a wind gathering cavity together with the windshield bottom panel; a total pressure detection hole is provided on the windshield side panel, and a first air outlet and a second air outlet are symmetrically provided on both sides of the total pressure detection hole; an inner surface of the windshield side panel region where the first air outlet and the second air outlet are located gradually contracts in a direction toward the first air outlet, the second air outlet and the total pressure detection hole to form a closing structure; a total pressure transmission pipe, one end of which is connected to the total pressure detection hole, and the other end of which is connected to the high-pressure end of the differential pressure sensor; A static pressure transmission pipe is provided on the side of the windshield bottom plate away from the windshield side plate. A static pressure detection hole is provided at one end of the static pressure transmission pipe close to the windshield bottom plate, and the other end is connected to the low-pressure end of the differential pressure sensor.

2. The flow velocity detection system according to claim 1, characterized in that: The windshield side panel is formed by connecting a plurality of panels to each other, and the windshield side panel includes a first panel, and a second panel and a third panel symmetrically arranged on both sides of the first panel, and an inner angle between the first panel, the second panel, and the third panel is greater than 90° and less than 120°; The total pressure detection hole is arranged on the first enclosure, the first air outlet is arranged on the second enclosure, and the second air outlet is arranged on the third enclosure.

3. The flow velocity detection system according to claim 1, wherein: The inner angle between the windshield side plate and the windshield bottom plate is greater than or equal to 90° and less than or equal to 120°.

4. The flow velocity detection system according to claim 1, wherein: It also includes a backflush assembly, which includes a first switching valve, a total pressure backflush pipe and a backflush gas source; The first switching valve has a first vent, a second vent, and a third vent, and the first switching valve is operable to connect the first vent with one of the second vent or the third vent; The total pressure transmission pipe is connected to the first vent, one end of the total pressure backflush pipe is connected to the second vent, and the high-pressure end of the differential pressure sensor is connected to the third vent; The other end of the total pressure backflush pipe is communicated with the backflush gas source.

5. The flow velocity detection system according to claim 4, characterized in that: The backflush assembly further includes a second switching valve and a static pressure backflush pipe; The second switching valve has a fourth vent, a fifth vent, and a sixth vent, and the second switching valve is operable to connect the fourth vent with one of the fifth vent and the sixth vent; The static pressure transmission pipe is connected to the fourth vent, one end of the static pressure backflush pipe is connected to the fifth vent, and the low pressure end of the differential pressure sensor is connected to the sixth vent; The other end of the static pressure backflush pipe is communicated with the backflush gas source.

6. The flow velocity detection system according to claim 4, characterized in that: The backflush gas source includes a backflush compressed gas tank and an air compressor. The air compressor is connected to the backflush compressed gas tank, and the backflush compressed gas tank is communicated with the other end of the total pressure backflush pipe.

7. A method for detecting the flue gas flow rate, using the flow rate detection system according to any one of claims 1-6, characterized in that, The method includes the following steps: Obtain the calibration coefficient of the Pitot tube, which is obtained through wind tunnel testing; Insert the Pitot tube into the flue, with the opening of the wind collecting cavity facing the direction of flue gas inflow, and the wind shield bottom plate perpendicular to the direction of flue gas inflow; Obtain the pressure difference between the total pressure detection hole and the static pressure detection hole of the Pitot tube sensed by the differential pressure sensor; Calculate the flue gas flow rate based on the Pitot tube calibration coefficient and the pressure difference; , where is the fluid velocity, is the calibration coefficient of the Pitot tube, is the fluid density, is the total pressure measured at the total pressure detection port, is the static pressure measured at the static pressure detection port.

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