Flow rate detection system and flue gas flow rate detection method

Abstract

The application relates to the technical field of fluid pressure detection, in particular to a flow rate detection system and a flue gas flow rate detection method. In the flow rate detection system, a wind-blocking side plate of a pitot tube is enclosed and installed on a wind-blocking bottom plate, and a wind-collecting cavity is formed by the wind-blocking side plate and the wind-blocking bottom plate; a total pressure detection hole is arranged on the wind-blocking side plate, and a first air outlet and a second air outlet are symmetrically arranged on the two sides of the total pressure detection hole; the region of the wind-blocking side plate where the first air outlet and the second air outlet are located is gradually contracted in the direction towards the first air outlet, the second air outlet and the total pressure detection hole, thereby forming a contracted structure; one end of a total pressure transmission pipe is communicated with the total pressure detection hole, and the other end is communicated with a high-pressure end of a differential pressure sensor; a static pressure transmission pipe is arranged on the side of the wind-blocking bottom plate away from the wind-blocking side plate, a static pressure detection hole is arranged on the end of the static pressure transmission pipe close to the wind-blocking bottom plate, and the other end is communicated with a low-pressure end of the differential pressure sensor. The pitot tube realizes physical anti-blocking, and can normally work in a flue with low flow rate and a large amount of particulate matters.

Description

TECHNICAL FIELD

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

[0002] The pitot tube, also known as an air speed tube or a wind speed tube, is a tubular device for measuring total pressure and static pressure of airflow to determine the airflow speed. The pitot tube is widely used in the fields of aerospace, ventilation ducts, environmental protection monitoring, wind power generation, thermal power industry, steel industry, cement industry and the like.

[0003] In the thermal power industry, a pulverized coal conveying pipeline or a chimney usually contains a large amount of particulate matters such as coal powder. In order to ensure the normal operation of the system equipment, the working state of the pulverized coal conveying pipeline and the chimney needs to be monitored in real time. If the traditional pitot tube is used for monitoring, it is easy to cause blockage, thereby leading to inaccurate measurement or even no measurement. In addition, the fluid flow rate in the pulverized coal conveying pipeline or the chimney is low. If the traditional pitot tube is used for monitoring, the differential pressure of the total pressure and the static pressure that can be sensed is small, thereby leading to a limited flow rate range of the detected flow rate and a problem of insufficient sensitivity. Therefore, the traditional pitot tube is not suitable for low flow rate flue measurement containing a large amount of particulate matters. SUMMARY

[0004] In order to overcome the problems in the related art, the present application provides a flow rate detection system and a flue gas flow rate detection method. The flow rate detection system is improved in structure based on the traditional pitot tube, so that the flow rate detection system has a physical anti-blocking function and can normally work in a low flow rate flue containing a large amount of particulate matters.

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

[0006] The pitot tube comprises a wind blocking bottom plate, a wind blocking side plate, a total pressure detection hole, a first air outlet, a second air outlet, a total pressure transmission pipe and a static pressure transmission pipe. The wind blocking side plate is installed on the wind blocking bottom plate and forms a wind collecting cavity together with the wind blocking bottom plate. The total pressure detection hole is arranged on the wind blocking side plate. The first air outlet and the second air outlet are symmetrically arranged on both sides of the total pressure detection hole. The inner surface of the wind blocking side plate region where the first air outlet and the second air outlet are located is gradually tapered in the direction of the first air outlet, the second air outlet and the total pressure detection hole, forming a tapered structure. One end of the total pressure transmission pipe is connected to the total pressure detection hole, and the other end of the total pressure transmission pipe is connected to the high pressure end of the differential pressure sensor. The static pressure transmission pipe is arranged on the side of the wind blocking bottom plate away from the wind blocking side plate. The static pressure transmission pipe is provided with a static pressure detection hole at the end close to the wind blocking bottom plate, and the other end of the static pressure transmission pipe is connected to the low pressure end of the differential pressure sensor.

[0007] In an optional embodiment, the wind blocking side plate is formed by a plurality of surrounding plates connected to each other, the wind blocking side plate comprises a first surrounding plate, a second surrounding plate and a third surrounding plate symmetrically arranged on both sides of the first surrounding plate, and an inner included angle between the first surrounding plate and the second surrounding plate and the third surrounding plate is greater than 90° and less than 120°; the total pressure detection hole is arranged on the first surrounding plate, the first exhaust port is arranged on the second surrounding plate, and the second exhaust port is arranged on the third surrounding plate.

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

[0009] In an optional embodiment, the back blowing assembly further comprises a second switching valve and a static pressure back blowing pipe; the second switching valve has a fourth air port, a fifth air port and a sixth air port, and the second switching valve can be actuated to make the fourth air port communicate with one of the fifth air port or the sixth air port; the static pressure transmission pipe communicates with the fourth air port, one end of the static pressure back blowing pipe communicates with the fifth air port, and the low pressure end of the differential pressure sensor communicates with the sixth air port; the other end of the static pressure back blowing pipe communicates with the back blowing gas source.

[0010] In an optional embodiment, the back blowing assembly further comprises a second switching valve and a static pressure back blowing pipe; the second switching valve has a fourth air port, a fifth air port and a sixth air port, and the second switching valve can be actuated to make the fourth air port communicate with one of the fifth air port or the sixth air port; the static pressure transmission pipe communicates with the fourth air port, one end of the static pressure back blowing pipe communicates with the fifth air port, and the low pressure end of the differential pressure sensor communicates with the sixth air port; the other end of the static pressure back blowing pipe communicates with the back blowing gas source.

[0011] In an optional embodiment, the back blowing gas source comprises a back blowing compressed gas tank and an air compressor, the air compressor is connected with the back blowing compressed gas tank, and the back blowing compressed gas tank communicates with the other end of the total pressure back blowing pipe.

[0012] According to the embodiments of the present application, a flue gas flow rate detection method is also provided, which uses the flow rate detection system described in the above embodiments, and the method comprises the following steps:

[0013] Obtaining a calibration coefficient of the Pitot tube, the calibration coefficient is obtained by wind tunnel test;

[0014] Inserting the Pitot tube into the flue, making the opening of the wind collecting cavity face the direction of flue gas inflow, and making the wind blocking bottom plate perpendicular to the direction of flue gas inflow;

[0015] acquire a pressure difference value of a total pressure detection hole and a static pressure detection hole of the pitot tube sensed by a differential pressure sensor;

[0016] calculate a flue gas flow rate according to a pitot tube calibration coefficient and the pressure difference value:

[0017] wherein V is a fluid velocity, k is a calibration coefficient of the pitot tube, p is a fluid density, P 全压 is a total pressure measured by the total pressure detection hole, P 静压 is a static pressure measured by the static pressure detection hole.

[0018] The technical scheme of the embodiment of the present application improves the structure of the traditional pitot tube, sets the wind gathering cavity capable of converting the fluid flow direction and improving the fluid flow rate, so that the pitot tube and the flow rate detection system have the physical anti-blocking function and can normally work in the flue containing a large amount of particulate matter at a lower flow rate.

[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] In order to better understand and implement, the present application is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

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

[0022] Figure 2 The structural schematic diagram of the pitot tube provided by the embodiment of the present application is shown.

[0023] Figure 3 The structural schematic diagram of the back flushing assembly provided by the embodiment of the present application is shown.

[0024] Corresponding reference signs: 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 transmission pipe; 14, static pressure transmission pipe; 15, total pressure detection hole; 16, static pressure detection hole; A, wind gathering cavity; 2, differential pressure sensor; 31, first switching valve; 311, first air vent; 312, second air vent; 313, third air vent; 32, total pressure back flushing pipe; 331, back flushing compressed air tank; 332, air compressor; 34, second switching valve; 341, fourth air vent; 342, fifth air vent; 343, sixth air vent; 35, static pressure back flushing pipe. DETAILED DESCRIPTION

[0025] To make the purposes, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0026] Therefore, the detailed description of the embodiments of the present application provided in the drawings below is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by a person of ordinary skill in the art without creative labor based on the embodiments in the present application are within the scope of protection of the present application.

[0027] In the flue application scenarios containing a large amount of particulate matters in the thermal power industry, the steel industry, the cement industry, and the like, measuring the flow velocity of the fluid in the flue is an important part, which relates to the stability and safety of the overall operation of the system equipment. The technical solutions of the embodiments are described taking the low flow velocity flue application scenario containing a large amount of particulate matters in the thermal power industry as an example, but the protection scope is not limited to the thermal power industry, and is also applicable to the low flow velocity fluid detection scenarios containing a large amount of particulate matters in other fields.

[0028] The traditional pitot tube is an S-shaped pitot tube or an L-shaped pitot tube. The total pressure detection hole of the traditional pitot tube is directly opposite the flow direction of the fluid. If there are particulate matters in the fluid, the particulate matters are easy to be directly blown into the total pressure detection hole, causing blockage, so that the measurement cannot be performed or the measurement is inaccurate. In addition, in the low flow velocity flue application scenario, for example, the flue gas flow velocity is lower than 5 m / s, the pressure difference between the total pressure and the static pressure sensed by the traditional pitot tube is small, so that the flow velocity range detected is limited. If the traditional pitot tube is forcibly applied to the detection of a lower flow velocity fluid, there will be problems such as insufficient sensitivity and large measurement error.

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

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

[0031] As shown in FIG. 2, Figure 2 Figure 3 The pitot tube 1 includes a wind-blocking bottom plate 11, a wind-blocking side plate 12, a total pressure transfer pipe 13, and a static pressure transfer pipe 14. ​

[0032] The wind deflector side plate 12 is mounted on the wind deflector bottom plate 11 and forms a wind collecting cavity A together with the wind deflector bottom plate 11; the middle part of the wind deflector side plate 12 is provided with a total pressure detection hole 15, and the first air outlet 124 and the second air outlet 125 are symmetrically arranged on both sides of the total pressure detection hole 15; the inner surface of the wind deflector side plate region where the first air outlet 124 and the second air outlet 125 are located is gradually tapered in the direction towards the first air outlet 124, the second air outlet 125 and the total pressure detection hole 15, forming a tapered structure, and the tapered structure is funnel-shaped when viewed from the angle opposite to the total pressure detection hole 15.

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

[0034] The static pressure transmission pipe 14 is arranged on the side of the wind deflector bottom plate 11 away from the wind deflector side plate 12, and the static pressure detection hole 16 is arranged at the end of the static pressure transmission pipe 14 close to the wind deflector bottom plate 11, and the other end is communicated with the low-pressure end of the differential pressure sensor 2. From the structure, the static pressure detection hole 16 can avoid the flow direction of the flue gas blown out from the first air outlet 124 and the second air outlet 125, so as to better sense the static pressure.

[0035] The pitot tube 1 is used to detect the flow rate in the flue containing particulate matter. When in use, the opening of the wind collecting cavity A of the pitot tube 1 is directed towards the direction of the flue gas flow, the wind deflector side plate 12 of the wind collecting cavity A blocks the particulate matter in the flue gas and makes it fall, and the tapered structure of the wind collecting cavity A speeds up the flue gas and guides it to be discharged at the first air outlet 124 and the second air outlet 125. At this time, the flue gas after being speeded up 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, so as to realize the total pressure detection of the fluid. At the same time, the static pressure detection hole 16 away from the wind deflector side plate 12 avoids the fluid interference of the air outlet and only senses the static pressure, so that the low-pressure end of the differential pressure sensor 2 senses the fluid static pressure. Finally, the fluid flow rate can be calculated according to the pressure difference between the fluid total pressure and the fluid static pressure and the calibration coefficient of the pitot tube, so as to realize the detection of the flue containing a large amount of particulate matter at a low flow rate, and the pitot tube 1 will not be blocked.

[0036] The technical scheme of the embodiment improves the structure of the traditional pitot tube 1, avoids the total pressure detection hole 15 directly facing the flow direction, makes the pitot tube 1 have a physical anti-blocking function, can improve the fluid flow rate to change the pressure at the total pressure detection hole 15, can sense a lower flow rate, and can normally work in the flue with a low flow rate and containing a large amount of particulate matter.

[0037] The ability of the flue gas flow rate to be increased 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 ability of the flue gas flow rate to be increased, in a preferred embodiment, the wind-blocking side plate 12 is formed by a plurality of surrounding plates connected to each other, the wind-blocking side plate 12 includes a first surrounding plate 121, a second surrounding plate 122 and a third surrounding plate 123 symmetrically arranged on both sides of the first surrounding plate 121, the total pressure detection hole 15 is arranged on the first surrounding plate 121 and located in the central region of the first surrounding plate 121, the first exhaust port 124 is arranged on the second surrounding plate 122 and located in the central region of the second surrounding plate 122, and the second exhaust port 125 is arranged on the third surrounding plate 123 and located in the central region of the third surrounding plate 123. The included angle between the first surrounding plate 121 and the second surrounding plate 122 is greater than 90° and less than 120°, and within this angle range, the greater the included angle between the first surrounding plate 121 and the second surrounding plate 122, the stronger the ability of the flue gas flow rate to be increased, and the greater the calibration coefficient of the pitot tube; the included angle between the first surrounding plate 121 and the third surrounding plate 123 is greater than 90° and less than 120°, and within this angle range, the greater the included angle between the first surrounding plate 121 and the third surrounding plate 123, the stronger the ability of the flue gas flow rate to be increased, and the greater the calibration coefficient of the pitot tube. By adopting the structural design of the pitot tube 1, the flue gas flow rate in the wind gathering cavity A is increased by more than 2 times, and the pitot tube can be applied to the measurement of fluid flow rate below 3 m / s.

[0038] Optionally, in the case that the included angles between the first surrounding plate 121 and the second surrounding plate 122 and between the first surrounding plate 121 and the third surrounding plate 123 are determined, the smaller the aperture of the first exhaust port, the greater the calibration coefficient of the pitot tube, and the smaller the aperture of the second exhaust port, the greater the calibration coefficient of the pitot tube.

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

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

[0041] In other embodiments, the second surrounding plate 122, the third surrounding plate 123 and the auxiliary surrounding plate 126 can all be arc-shaped, the inner surfaces of the second surrounding plate 122 and the third surrounding plate 123 gradually shrink in the direction towards the first exhaust port 124, the second exhaust port 125 and the total pressure detection hole 15, forming a closing structure to realize the wind gathering effect.

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

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

[0044] As shown in Figure 3 In the specific structure design, the back blowing assembly includes a first switching valve 31, a total pressure back blowing pipe 32 and a back blowing gas source; the first switching valve 31 has a first air port 311, a second air port 312 and a third air port 313, and the first switching valve 31 can be actuated to make the first air port 311 communicate with one of the second air port 312 or the third air port 313; the total pressure transmission pipe 13 communicates with the first air port 311, one end of the total pressure back blowing pipe 32 communicates with the second air port 312, and the high pressure end of the differential pressure sensor 2 communicates with the third air port 313; the other end of the total pressure back blowing pipe 32 communicates with the back blowing gas source.

[0045] In the application process, when the total pressure is measured by the differential pressure sensor 2, the first switching valve 31 is actuated to make the first air port 311 communicate with the third air port 313; when the total pressure transmission pipeline is purged by the back blowing gas source, the first switching valve 31 is actuated to make the first air port 311 communicate with the second air port 312, so that the back blowing gas source reaches the second air port 312 of the first switching valve 31 through the total pressure back blowing pipe 32, and then flows out from the first air port 311 to blow to the wind collecting cavity A of the pitot tube 1 through the total pressure transmission pipe 13.

[0046] Optionally, in order to realize the purging of the static pressure detection pipeline and further improve the anti-blocking ability of the flow rate detection system and the detection accuracy, the back blowing assembly further includes a second switching valve 34 and a static pressure back blowing pipe 35; the second switching valve 34 has a fourth air port 341, a fifth air port 342 and a sixth air port 343, and the second switching valve 34 can be actuated to make the fourth air port 341 communicate with one of the fifth air port 342 or the sixth air port 343; the static pressure transmission pipe 14 communicates with the fourth air port 341, one end of the static pressure back blowing pipe 35 communicates with the fifth air port 342, and the low pressure end of the differential pressure sensor 2 communicates with the sixth air port 343; the other end of the static pressure back blowing pipe 35 communicates with the back blowing gas source.

[0047] During application, when the static pressure is measured by the differential pressure sensor 2, the second switching valve 34 is activated, connecting the fourth vent 341 with the sixth vent 343. When the static pressure transmission pipe 14 is purged by the backflush air source, the second switching valve 34 is activated, connecting the fourth vent 341 with the fifth vent 342. In this way, the backflush air source reaches the fifth vent 342 of the second switching valve 34 through the static pressure backflush pipe 35, and then flows out from the fourth vent 341, passing through the static pressure transmission pipe 14 and blowing into the air-gathering chamber A of the Pitot tube 1.

[0048] Optionally, the backflush air 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 connected to the other end of the total pressure backflush pipe 32. The air compressor 332 can improve the power of the backflush air source and achieve a better purging effect.

[0049] The technical solution of this embodiment improves the structure of the traditional Pitot tube, avoiding direct alignment of the total pressure detection port with the incoming flow direction. This gives the Pitot tube a physical anti-clogging function and increases the fluid velocity, thereby changing the pressure at the total pressure detection port. It can sense even lower flow velocities and operate normally in low-velocity flues containing a large amount of particulate matter. Compared to the traditional Pitot tube, the improved Pitot tube achieves a wind speed measurement lower limit of 3 m / s, and a flow velocity measurement lower limit improved by 40%.

[0050] Furthermore, the flow rate detection system can also purge the detection pipeline through the backflushing component to prevent dust from accumulating on the Pitot tube and the detection pipeline, thereby better achieving the anti-clogging function and improving the detection accuracy of low fluid flow rates.

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

[0052] The method for detecting flue gas velocity includes the following steps:

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

[0054] S2: Insert the Pitot tube into the flue, so that the opening of the air-gathering chamber faces the direction of flue gas inflow, and the bottom plate of the wind deflector is perpendicular to the direction of flue gas inflow.

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

[0056] S4: The flue gas velocity is calculated based on the Pitot tube calibration coefficient and the pressure difference.

[0057] Where V is the fluid velocity, k is the Pitot tube calibration coefficient, ρ is the fluid density, and P全压 P is the total pressure measured by the total pressure detection port 静压 P is the static pressure measured by the static pressure detection port.

[0058] When the smoke flow rate is measured using the pitot tube of the above embodiment, according to the Bernoulli equation of ideal incompressible gas, the sum of the kinetic energy, potential energy and pressure energy of unit fluid is a constant, which can be expressed by formula one: Wherein, p is the fluid density; g is the acceleration of gravity; P is the pressure energy of the fluid; V is the fluid velocity; C is the total energy of unit fluid. In the case of constant gravitational potential energy, the sum of the kinetic energy and pressure energy of the fluid is also a constant, and the height difference of the pitot tube during measurement can be ignored, which meets the condition of constant gravitational potential energy.

[0059] The total pressure measured by the total pressure detection port is P 全压 , the static pressure measured by the static pressure detection port is P 静压 , and formula two is obtained according to the Bernoulli equation:

[0060] The calibration coefficient of the improved pitot tube is k, and the specific value is obtained by wind tunnel test. The calibration coefficient k of the pitot tube is brought into formula two, and formula three is obtained by transformation: Thus, the smoke flow rate is calculated.

[0061] The technical scheme of the embodiment, when the improved pitot tube and the flow rate detection system are used to measure the fluid flow rate of the flue gas pipeline or chimney of the thermal power industry, the smoke is blown to the wind collecting cavity of the pitot tube, the wind blocking side plate of the wind collecting cavity blocks the smoke and the particulate matters therein, avoids the smoke directly blowing to the total pressure detection hole, and avoids the free falling of the particulate matters. After the smoke flow direction is changed, the smoke is blown out from the exhaust port. At the same time, due to the converging structure of the wind collecting cavity, the wind speed is increased, the fluid pressure entering the total pressure detection port is increased, so that the pitot tube can be applied to the detection of lower fluid flow rate.

[0062] Further, the flow rate detection system can also blow the detection pipeline through the back blowing assembly to avoid the accumulation of smoke dust on the pitot tube and the detection pipeline, so as to better realize the anti-blocking function and improve the detection accuracy of the fluid flow rate.

[0063] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like is based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship that the product of the application is usually placed in, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", and the like appearing in the description of the present application are only used to distinguish the description and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", and the like appearing in the description of the present application do not mean that the component must be absolutely horizontal or vertical, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "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 explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense, for example, they can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[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 "a", "said" and "the" 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 means and includes any or all possible combinations of one or more associated listed items.

[0066] Note that the above is only the preferred embodiment of the present application and the technical principle applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the 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, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A flow rate detection system, characterized by, Comprise: pitot tube and differential pressure sensor; The pitot tube comprises: windshield bottom plate; windshield side plate, which is enclosed and mounted on the windshield bottom plate and forms a wind collecting cavity with the windshield bottom plate; The windshield side plate is provided with a total pressure detection hole, and first and second air outlets are symmetrically arranged on both sides of the total pressure detection hole; The inner surface of the windshield side plate region where the first and second air outlets are located gradually shrinks in the direction towards the first and second air outlets and the total pressure detection hole, forming a converging structure; total pressure transmission pipe, one end of which communicates with the total pressure detection hole, and the other end of which communicates with the high pressure end of the differential pressure sensor; static pressure transmission pipe, which is arranged on the side of the windshield bottom plate away from the windshield side plate, and is provided with a static pressure detection hole at one end close to the windshield bottom plate and communicates with the low pressure end of the differential pressure sensor at the other end; back blowing assembly, which comprises a first switching valve, a second switching valve, a total pressure back blowing pipe, a static pressure back blowing pipe and a back blowing gas source; The first switching valve has a first air port, a second air port and a third air port, and can be actuated to make the first air port communicate with one of the second air port or the third air port; The total pressure transmission pipe communicates with the first air port, one end of the total pressure back blowing pipe communicates with the second air port, and the high pressure end of the differential pressure sensor communicates with the third air port; The other end of the total pressure back blowing pipe communicates with the back blowing gas source; The second switching valve has a fourth air port, a fifth air port and a sixth air port, and can be actuated to make the fourth air port communicate with one of the fifth air port or the sixth air port; The static pressure transmission pipe communicates with the fourth air port, one end of the static pressure back blowing pipe communicates with the fifth air port, and the low pressure end of the differential pressure sensor communicates with the sixth air port; The other end of the static pressure back blowing pipe communicates with the back blowing gas source; The back blowing gas source comprises a back blowing compressed gas tank and an air compressor, the air compressor is connected with the back blowing compressed gas tank, and the back blowing compressed gas tank communicates with the other end of the total pressure back blowing pipe.

2. The flow rate detection system according to claim 1, wherein: The windshield side plate is formed by connecting a plurality of surrounding plates, and comprises a first surrounding plate, a second surrounding plate and a third surrounding plate symmetrically arranged on both sides of the first surrounding plate, and the included angle between the first surrounding plate and the second surrounding plate and the third surrounding plate is greater than 90° and less than 120°; The total pressure detection hole is arranged on the first surrounding plate, the first air outlet is arranged on the second surrounding plate, and the second air outlet is arranged on the third surrounding plate.

3. The flow rate detection system according to claim 1, wherein: The included 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. A method of detecting the flow rate of a flue gas stream using a flow rate detection system according to any one of claims 1 to 3, characterised in that, The method comprises the following steps: obtaining the calibration coefficient of the pitot tube, which is obtained by wind tunnel test; The pitot tube is inserted into the flue, the opening of the wind collecting cavity is directed to the direction of the flue gas inflow, and the wind blocking bottom plate is perpendicular to the direction of the flue gas inflow; 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 is acquired; The flue gas flow rate is calculated according to the pitot tube calibration coefficient and the pressure difference value: wherein, is the fluid velocity, is the calibration coefficient of the pitot tube, is the fluid density, is the total pressure measured by the total pressure detection port, is the static pressure measured by the static pressure detection port.

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