Pitot tube and flow velocity detection system

Abstract

The utility model provides a pitot tube and a flow velocity detection system, and the pitot tube comprises a total pressure guide tube; a static pressure guide pipe; the sampling nozzle is a C-shaped pipe, and the sampling nozzle comprises sample injection openings in the two ends and a connecting opening located between the two sample injection openings; the far end of the total pressure guide pipe and / or the far end of the static pressure guide pipe are / is connected with the sampling nozzle through the connector. According to the pitot tube provided by the invention, smoke dust is difficult to deposit on the sampling nozzle of the C-shaped tube; the area of the opening facing / backing to the fluid is far smaller than the inner surface area of the sampling nozzle, and even if smoke dust is deposited on the inner surface of the sampling nozzle, the sampling nozzle can be used for flow velocity detection for a longer time; and when smoke dust deposition occurs in long-term use, high-pressure gas can be introduced from one sample introduction opening of the sampling nozzle and flows out from the other sample introduction opening, so that the stroke of the high-pressure gas is smaller, the pressure loss is small, and smoke dust particles are easier to clean.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of stationary pollution source monitoring, and in particular to a pitot tube and a flow rate detection system. BACKGROUND

[0002] In the monitoring of particulate matters of stationary pollution sources, the detection items include the detection of exhaust flow rate and flow (refer to GB / T16157-1996 “Method for Determination of Particulate Matter and Sampling of Gaseous Pollutants in Exhaust Gas of Stationary Pollution Sources”, hereinafter referred to as “national standard document”). Currently, an S-shaped pitot tube (its structure is described in the “national standard document” and the present application Figure 1 ) is commonly used. Among the two openings of the S-shaped pitot tube, one opening (such as the right opening a11) faces the airflow for detecting the total pressure (also referred to as “full pressure”), and the other opening (such as the left opening a11) faces away from the airflow for detecting the static pressure, so that the flow rate can be obtained according to the total pressure, the static pressure and the Bernoulli equation. The opening of the above-mentioned existing S-shaped pitot tube is large, which basically meets the requirements of the national detection department when temporarily checking and detecting, but for the case of long-time detection required by enterprises, such as the matrix flow system shown in the present application Figure 2 、 Figure 3 , the S-shaped pitot tube needs to be set in the flue for a long time, and the S-shaped pitot tube still has the problem of being easily blocked.

[0003] Therefore, how to prolong the use time of the pitot tube and facilitate cleaning is a problem that needs to be solved at present. CONTENT OF THE UTILITY MODEL

[0004] In order to solve the problems in the prior art, the present application provides a pitot tube and a flow rate detection system. The technical scheme of the present application is as follows:

[0005] A pitot tube, comprising:

[0006] a total pressure draft tube;

[0007] a static pressure draft tube;

[0008] a sampling nozzle, the sampling nozzle being a C-shaped tube, the sampling nozzle comprising two sample inlet openings at two ends and a connecting port between the two sample inlet openings;

[0009] wherein the distal end of the total pressure draft tube and / or the static pressure draft tube is connected with the sampling nozzle through the connecting port.

[0010] Further, the distal end of the static pressure draft tube is connected with the sampling nozzle.

[0011] Further, the distal end of the total pressure draft tube and the static pressure draft tube is respectively connected with the sampling nozzle, and the two sampling nozzles are arranged oppositely.

[0012] Further, the distance between the connection port and one of the sample inlets of the sampling nozzle is not equal to the distance between the connection port and the other sample inlet.

[0013] Further, the distal ends of the sampling nozzle and the total pressure draft tube or the static pressure draft tube connected thereto are located in the same plane.

[0014] Further, the planes of the two sample inlets of the sampling nozzle are parallel to each other or in the same plane, and the axis of the distal ends of the total pressure draft tube and / or the static pressure draft tube connected to the sampling nozzle is parallel to the planes of the two sample inlets.

[0015] Further, the inner diameters of the sampling nozzle and the total pressure draft tube and / or the static pressure draft tube connected thereto are the same.

[0016] In addition, the application also provides a flow rate detection system, which comprises: two or more Pitot tubes, each of which is independently selected from any of the above-mentioned Pitot tubes.

[0017] Further, the flow rate detection system comprises one or more linear detection modules, and the linear detection modules are provided with two or more Pitot tubes.

[0018] Further, the linear detection module further comprises: a plurality of communication tubes, the proximal ends of the plurality of communication tubes are each independently connected to the distal ends of the total pressure draft tube and the static pressure draft tube of each Pitot tube.

[0019] Further, the linear detection module further comprises: an outer wrapping tube, and the plurality of communication tubes are arranged in the outer wrapping tube.

[0020] Further, the flow rate detection system comprises: two or more linear detection modules.

[0021] Further, the flow rate detection system further comprises: a differential pressure detection module, which detects the pressure / differential pressure in the total pressure draft tube and the static pressure draft tube.

[0022] Further, the differential pressure detection module comprises a pressure sensor, which detects the pressure in the total pressure draft tube and the static pressure draft tube, respectively; or the differential pressure detection module comprises a differential pressure gauge, which detects the differential pressure in the total pressure draft tube and the static pressure draft tube of each Pitot tube.

[0023] Further, the flow rate detection system further comprises: a control module, which obtains the mathematical average value of the flow rate of each Pitot tube through the detection results of the differential pressure detection module.

[0024] The sampling nozzle of the pitot tube provided by the present application is in the shape of a C-shaped tube, which is difficult to deposit soot; the opening area of the pitot tube towards / away from the fluid is much smaller than the inner surface area of the sampling nozzle, so that the sampling nozzle can be used for a longer time for flow rate detection compared with the prior art, especially when the connecting port is arranged at the upper part of the sampling nozzle and the distance between the connecting port and one of the sampling openings is not equal to the distance between the connecting port and the other sampling opening, the soot deposited on the inner surface of the sampling nozzle will be deposited at the lower part of the inner surface of the sampling nozzle due to the effect of gravity, and the total pressure and static pressure guide tubes will not be blocked, so that the service life of the pitot tube can be further prolonged; even if soot is deposited during long-term use, in addition to the high-pressure gas being introduced from the distal end of the pitot tube to clean the deposited soot particles as in the prior art, the high-pressure gas can also be introduced from one of the sampling openings, and the high-pressure gas flows out from the other sampling opening, so that the high-pressure gas has a smaller stroke and smaller pressure loss, and the soot particles can be cleaned more easily. In addition, the flow rate detection system provided by the present application, especially when the flow rate detection system comprises a plurality of connecting tubes, the pressure / differential pressure detection device can be arranged at the distal end (the end far away from the pitot tube) of the connecting tube, so that the mathematical average of each flow rate required by the “national standard document” can be detected, and the distal end can be closed, which meets the requirements of the detection principle (Bernoulli equation).

[0025] The above description is only a summary of the technical solutions of the present application, in order to make the technical means of the present application more clear and understandable, to the extent that the person skilled in the art can implement the content of the description, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described below. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 : Schematic diagram of the structure of the prior art pitot tube;

[0027] Figure 2 : Schematic diagram of the structure of the prior art matrix flow system from the front view;

[0028] Figure 3 : Schematic diagram of the structure of the prior art matrix flow system from the left view;

[0029] Figure 4 : Schematic diagram of the structure of the pitot tube from the front view in an embodiment of the present application;

[0030] Figure 5 : Schematic diagram of the structure of the pitot tube from the left view in an embodiment of the present application;

[0031] Figure 6 : Schematic diagram of the structure of the sampling port of the pitot tube in an embodiment of the present application;

[0032] Figure 7 : linear detection module structure schematic diagram.

[0033] Legend:

[0034] a10, pitot tube; a11, opening; a12, total pressure pilot pipe; a13, static pressure pilot pipe; a20, total pressure collection pipe; a30, static pressure collection pipe; a40, connecting pipe;

[0035] b10, pitot tube; b11, sampling nozzle; b11-1, sampling opening; b11-2, connecting port; b12, total pressure pilot pipe; b13, static pressure pilot pipe; b20, outer package pipe; b30, communication pipe; b40, pressure detection module;

[0036] r, deposited soot. DETAILED DESCRIPTION

[0037] The following embodiments of the present application are only used to illustrate the specific embodiments of the present application, and these embodiments cannot be understood as the limitation of the present application. Any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods, which fall within the protection scope of the present application.

[0038] Those skilled in the art should understand that in the disclosure of the present application, the terms "first", "second", "third", "fourth", "fifth" and the like are only used to distinguish different structures, and do not limit the number, connection relationship and the like of specific structures; in addition, the orientation or position relationship indicated by "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or position relationship shown in the drawings, which 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, therefore the above terms cannot be understood as the limitation of the present application.

[0039] The present embodiment provides a pitot tube b10, as shown in the drawings, comprising: Figures 4-6

[0040] total pressure pilot pipe b12;

[0041] static pressure pilot pipe b13;

[0042] sampling nozzle b11, the sampling nozzle b11 is a C-shaped pipe, the sampling nozzle b11 comprises sampling openings b11-1 at both ends and a connecting port b11-2 between the two sampling openings;

[0043] ​The sampling nozzle is connected to the distal end of the total pressure guiding tube b12 and / or the static pressure guiding tube b13 via the connecting port b11-2.

[0044] In this application, "distal end" refers to the end of the Pitot tube closest to the injection opening; "proximal end" is the opposite end of "distal end", that is, the end of the Pitot tube closest to the end used for detecting pressure / differential pressure.

[0045] Regarding the materials used for Pitot tubes, they can be polymeric materials and / or metallic materials. Specifically, for polymeric materials, high-temperature resistant polyimide (PI), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyamide-imide (PAI), polytetrafluoroethylene (PTFE), and silicone resins can be selected; for metallic materials, stainless steel (grades 304, 316, 316L, 321, etc.), alloy steel (grades P11, P22, P91, etc.), aluminum and aluminum alloys, nickel-based alloys, titanium and titanium alloys, etc.

[0046] like Figure 1 As shown, the existing Pitot tube has only one opening at the distal end of the pressure guiding tube (total pressure guiding tube a12 / static pressure guiding tube a13), which restricts gas flow. This causes dust particles to accumulate and accumulate at the opening a11 of the pressure guiding tube, which is difficult to remove and can easily clog the Pitot tube, making it unsuitable for flow rate detection.

[0047] As in this application Figures 4-6 As shown, the Pitot tube b10 provided in this application is C-shaped. When used for detection, its two ends are connected, allowing for smooth gas flow and thus minimizing dust deposition. Furthermore, during operation, the opening area facing / away from the fluid is only twice the inner cross-sectional area of ​​the sampling nozzle, while the area where dust can be deposited by the sampling nozzle is the entire inner surface of the C-shaped tube, which is significantly larger than the former. Therefore, compared to existing Pitot tubes, the Pitot tube provided in this embodiment can be used for flow rate detection for a longer period.

[0048] In addition, even if the Pitot tube provided in this embodiment accumulates soot during long-term use, in addition to passing high-pressure gas from the distal end to clean up the deposited soot particles as with existing Pitot tubes, high-pressure gas can also be passed through one inlet opening b11-1 of the sampling nozzle b11, and the high-pressure gas flows out from the other inlet opening b11-1. The high-pressure gas has a shorter stroke and less pressure loss, making it easier to clean up the soot particles.

[0049] Preferably, the sampling nozzle is connected to the distal end of the static pressure guiding tube b13. Since the opening of the static pressure guiding tube faces away from the fluid, a low-pressure vortex zone easily forms at its opening, making it more prone to dust deposition. By providing a sampling nozzle b11 on the static pressure guiding tube b13, the service life of the Pitot tube can be extended.

[0050] Of course, more preferably, the sampling nozzle b11 is connected to the distal end of the total pressure pilot pipe b12 and the static pressure pilot pipe b13 respectively, and the two sampling nozzles b11 are arranged opposite to each other so as to be used for fluid respectively.

[0051] In one embodiment, as shown in Figures 4-6 The distance between the connecting port b11-2 and one of the sampling openings b11-1 is not equal to the distance between the connecting port b11-2 and the other sampling opening b11-1.

[0052] In the present application, the distance between the connecting port b11-2 and the sampling opening b11-1 refers to the minimum distance between all points of the edge of the connecting port b11-2 and all points of the edge of the sampling opening b11-1.

[0053] As shown in Figure 6 The distance between the connecting port b11-2 and the upper sampling opening b11-1 is less than the distance between the connecting port b11-2 and the lower sampling opening b11-1.

[0054] Therefore, when used for detection, the sampling opening b11-1 closer to the connecting port b11-2 can be arranged at the upper part, and the sampling opening b11-1 farther from the connecting port b11-2 can be arranged at the lower part, that is, the connecting port b11-2 can be arranged at the upper part, as shown in Figure 6 Due to the effect of gravity, even if the smoke dust is deposited, the deposited smoke dust will be deposited at the lower part of the inner surface of the sampling nozzle b11, and will not cause blockage of the total pressure pilot pipe b12 and the static pressure pilot pipe b13, thereby further prolonging the service life of the pitot tube.

[0055] In one embodiment, as shown in Figure 6 The distal end of the sampling nozzle b11 and the total pressure pilot pipe b12 or the static pressure pilot pipe b13 connected thereto are located in the same plane (that is, the axis of the sampling nozzle b11 and the axis of the distal end of the total pressure pilot pipe b12 or the distal end of the static pressure pilot pipe b13 connected thereto are located in the same plane).

[0056] In one embodiment, as shown in Figures 4-6 The planes where the two sampling openings b11-1 of the sampling nozzle b11 are located are parallel to each other or located in the same plane (specifically, in the present embodiment, the two planes are located in the same plane), and the axis of the distal end of the total pressure pilot pipe b12 and / or the static pressure pilot pipe b13 connected to the sampling nozzle b11 is parallel to the planes where the two sampling openings b11-1 are located.

[0057] In one embodiment, the inner diameter of the sampling nozzle b11 and the total pressure pilot pipe b12 and / or the static pressure pilot pipe b13 connected thereto is the same.

[0058] Based on the above embodiments, this application also provides a flow rate detection system, such as... Figure 7 As shown, it includes: two or more pitot tubes b10, each of which is independently any of the above-mentioned pitot tubes b10.

[0059] In one embodiment, the flow rate detection system includes one or more (e.g., 1, 2, 3, 4, 5 or more) linear detection modules, wherein two or more Pitot tubes b10 are disposed on the linear detection modules.

[0060] In this application, "linear" means that each pitot tube b10 is arranged in a "linear" manner, specifically as a straight line / curve. In this embodiment, it is preferred that they are arranged in a straight line.

[0061] When there are multiple linear detection modules, for flues with rectangular or circular cross-sections, these multiple linear detection modules can be arranged in parallel or intersecting ways. This allows multiple Pitot tubes to be set on the cross-section of the flue (e.g., in an array) to detect the fluid velocity at multiple points on the flue cross-section. Thus, the flow velocity of the fluid in the flue can be determined by the flow velocity at each point (e.g., the mathematical average of the flow velocities at each point).

[0062] In one embodiment, the linear detection module further includes: a plurality of connecting tubes b30, the proximal end (the end closest to the Pitot tube) of each of the plurality of connecting tubes b30 being independently connected to the distal end of the total pressure guide tube and the static pressure guide tube of each Pitot tube.

[0063] For example, in the "7 Determination of Exhaust Velocity and Flow Rate" section of the "National Standard Document", it is required to calculate the average velocity at each point to reflect the fluid velocity in the flue, etc.

[0064] However, as Figures 2-3 As shown, for existing matrix flow systems, regardless of total pressure or static pressure, the total pressure / static pressure or pressure difference at the aggregation point is measured after summing the total pressure / static pressure or pressure difference from multiple Pitot tubes. The measured average flow velocity is:

[0065]

[0066] In this embodiment, the proximal ends of multiple connecting pipes b30 are independently connected to the distal ends of the total pressure guide pipe and static pressure guide pipe of each Pitot tube. Therefore, the pressure difference of each Pitot tube can be independently measured through the proximal ends of the connecting pipes b30, thereby obtaining the average flow velocity.

[0067]

[0068] In the above two formulas:

[0069] V1, V2 - flow velocity, unit m / s;

[0070] F - velocity field coefficient;

[0071] C - Pitot tube coefficient;

[0072] Pd - differential pressure signal.

[0073] It can be known that the average flow velocity obtained by the embodiment (especially for the case of including multiple linear detection modules) is the mathematical average of each flow velocity required by the "national standard document". It can be known through mathematical derivation that the result V1 of the existing scheme is greater than the result V2 that can be detected by the embodiment. That is, the result that can be detected by the existing matrix flow system is greater than the average of the flow velocities required by the "national standard document", and the flow velocity of the fluid in the flue and the like cannot be accurately detected.

[0074] In addition, when using a Pitot tube to detect the flow velocity, the Bernoulli equation used requires the proximal end to be closed, and in the existing scheme, the total pressure / static pressure openings of each Pitot tube are connected regardless of the detection of total pressure or static pressure, so the existing matrix flow system does not fully meet the requirements of the Bernoulli equation, and itself cannot be used for accurate detection of flow velocity.

[0075] Therefore, compared with the existing matrix flow system, the scheme provided by the embodiment can set a pressure / differential pressure detection device at the distal end (the end away from the Pitot tube) of the communication pipe b30, so as to be able to detect the mathematical average of each flow velocity required by the "national standard document", and the distal end can be closed, thereby meeting the requirements of the detection principle (Bernoulli equation).

[0076] In one embodiment, as shown in Figure 7 The linear detection module further comprises an outer pipe b20, and the plurality of communication pipes b30 are arranged in the outer pipe.

[0077] Specifically, the proximal end of the communication pipe b30, the distal end of the total pressure pressure guide pipe b12 and the static pressure pressure guide pipe b13 of the Pitot tube b10 can be connected to the side wall of the outer pipe b20 through a flange, so as to realize the connection of the communication pipe b30 and the total pressure pressure guide pipe b12 / static pressure pressure guide pipe b13.

[0078] In one embodiment, the flow velocity detection system further comprises a differential pressure detection module, which detects the pressure / differential pressure in each of the total pressure pressure guide pipe and the static pressure pressure guide pipe.

[0079] Specifically, the differential pressure detection module comprises a pressure sensor, which detects the pressure in the total pressure pressure guide pipe and the static pressure pressure guide pipe, respectively.

[0080] In addition, the differential pressure detection module can also include a differential pressure meter for detecting the differential pressure between the total pressure pilot pipe b12 and the static pressure pilot pipe b13 of each pitot tube b10.

[0081] As shown in Figure 7 , the differential pressure detection module can specifically detect the pressure / differential pressure through the distal end of the communication pipe b30.

[0082] In one embodiment, the flow rate detection system further includes a control module for obtaining the mathematical average of the flow rate of each pitot tube through the detection result of the differential pressure detection module.

[0083] As for the control module, it can include a controller (such as a single-chip microcomputer, etc.), so as to obtain the average flow rate (V2) through the above formula according to the detection data (pressure / differential pressure) of the differential pressure detection module.

[0084] Of course, the control module can also include an output unit (such as a display screen, a loudspeaker, etc.) to output the average flow rate.

[0085] In addition, the flow rate detection system of the present application can also include a pressure detection module b40 for detecting the pressure in the pipeline such as a flue, etc. Thus, the detection of the flow rate is realized at the same time as the detection of the pressure in the pipeline, i.e., the detection of two items specified in the "national standard document" is realized at the same time.

[0086] As for the pressure detection module b40, it can specifically be a pipeline as shown in Figure 7 , the upper end of which is connected with a pressure sensor for pressure detection; or a pressure sensor can be built in the pipeline for pressure detection.

[0087] Although the embodiments of the present application are described above, the present application is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and guiding, but not limiting. Those skilled in the art can make many forms under the guidance of the present specification and without departing from the scope protected by the claims of the present application, which all belong to the present application claimed for protection.

Claims

1. A pitot tube characterized by, The pitot tube comprises: a total pressure tube; a static pressure tube; a sampling nozzle, which is a C-shaped tube, and comprises two sample inlet openings and a connecting port between the two sample inlet openings; wherein the distal end of the total pressure tube and / or the static pressure tube is connected with the sampling nozzle through the connecting port.

2. The pitot tube according to claim 1, wherein: the distal end of the static pressure tube is connected with the sampling nozzle.

3. The pitot tube according to claim 1, wherein: the distal end of the total pressure tube and the distal end of the static pressure tube are respectively connected with the sampling nozzle, and the two sampling nozzles are arranged oppositely.

4. The pitot tube according to claim 1, wherein: the distance between the connecting port and one of the sample inlet openings of the sampling nozzle is not equal to the distance between the connecting port and the other sample inlet opening.

5. The pitot tube according to claim 1, wherein: the distal end of the total pressure tube or the static pressure tube connected with the sampling nozzle is located in the same plane as the sampling nozzle.

6. The pitot tube according to claim 1, wherein: the planes of the two sample inlet openings of the sampling nozzle are parallel to each other or located in the same plane, and the axis of the distal end of the total pressure tube and / or the static pressure tube connected with the sampling nozzle is parallel to the planes of the two sample inlet openings.

7. The pitot tube according to claim 1, wherein: the inner diameter of the sampling nozzle and the total pressure tube and / or the static pressure tube connected with the sampling nozzle are the same.

8. A flow rate detection system characterized by, The flow rate detection system comprises: two or more pitot tubes, each of which is independently selected from the pitot tube according to any one of claims 1 to 7.

9. The flow rate detection system according to claim 8, wherein: the system comprises one or more linear detection modules, and two or more pitot tubes are arranged on each linear detection module.

10. The flow rate detection system according to claim 9, wherein: each linear detection module further comprises: a plurality of communication tubes, and the proximal end of each communication tube is independently connected with the distal end of the total pressure tube and / or the static pressure tube of each pitot tube.

11. The flow rate detection system according to claim 10, wherein: each linear detection module further comprises: an outer tube, and the plurality of communication tubes are arranged in the outer tube.

12. The flow rate detection system of claim 11, wherein, The flow rate detection system comprises: two or more linear detection modules.

13. The flow rate detection system of any one of claims 8 to 12, wherein, The flow rate detection system further comprises: a differential pressure detection module, which detects the pressure / differential pressure in each total pressure tube and static pressure tube.

14. The flow rate detection system according to claim 13, wherein: the differential pressure detection module comprises a pressure sensor, which detects the pressure in each total pressure tube and static pressure tube; or the differential pressure detection module comprises a differential pressure gauge, which detects the differential pressure in the total pressure tube and the static pressure tube of each pitot tube.

15. The flow rate detection system of claim 13, wherein, The flow rate detection system further comprises: a control module, which obtains the mathematical average value of the flow rate of each pitot tube based on the detection results of the differential pressure detection module.

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