Pitot tube and flow velocity detection system

Abstract

The invention 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; when smoke dust deposition occurs after 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 fixed pollution source monitoring, and in particular to a Pitot tube and a flow velocity detection system. Background Art

[0002] In the monitoring of particulate matter from fixed pollution sources, the detection items include the detection of exhaust velocity and flow rate (refer to GB / T16157-1996 "Methods for the determination of particulate matter in exhaust gas from fixed pollution sources and sampling of gaseous pollutants", hereinafter referred to as the "national standard document"). At present, the commonly used S-shaped pitot tube (its structure is shown in Figure 17 of the "national standard document" and this application) Figure 1 ), of which one opening (such as the right opening a11) faces the airflow to detect the total pressure (also called "total pressure"), and the other opening (such as the left opening a11) faces away from the airflow to detect the static pressure, so that the flow rate can be obtained according to the total pressure, static pressure and Bernoulli equation. The above-mentioned existing S-type pitot tube has a large opening, which basically meets the needs of the national inspection department for temporary spot checks. However, for enterprises that need long-term inspections, such as those used in this application Figure 2 , Figure 3 In the matrix flow system shown in the figure, the S-type Pitot tube needs to be set in the flue for a long time, and the S-type Pitot tube still has the problem of being easily blocked.

[0003] Therefore, how to extend the service life of the Pitot tube and make it easy to clean is an issue that needs to be urgently addressed. Summary of the invention

[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 solution of the present application is as follows:

[0005] 1. A pitot tube, comprising:

[0006] Total pressure pipe;

[0007] Static pressure pipe;

[0008] A sampling nozzle, the sampling nozzle is a C-shaped tube, and the sampling nozzle includes sampling openings at both ends and a connecting port located between the two sampling openings;

[0009] Wherein, the distal end of the total pressure guiding pipe and / or the static pressure guiding pipe is connected to the sampling nozzle via the connecting port.

[0010] 2. The Pitot tube as described in item 1, wherein the sampling nozzle is connected to the distal end of the static pressure pipe.

[0011] 3. The Pitot tube as described in item 1, wherein the distal ends of the total pressure conducting tube and the static pressure conducting tube are respectively connected to the sampling nozzles, and the two sampling nozzles are arranged back to back.

[0012] 4. A Pitot tube as described in item 1, wherein the distance between the connecting port and one of the injection openings of the sampling nozzle where it is located is not equal to the distance between the connecting port and another injection opening.

[0013] 5. The Pitot tube as described in item 1, wherein the sampling nozzle and the distal end of the total pressure pipe or the static pressure pipe connected thereto are located in the same plane.

[0014] 6. A Pitot tube as described in item 1, wherein the planes where the two sampling openings of the sampling nozzle are located are parallel to each other or located in the same plane, and the axis of the distal end of the total pressure pipe and / or the static pressure pipe connected to the sampling nozzle is parallel to the plane where the two sampling openings are located.

[0015] 7. The Pitot tube as described in item 1, wherein the inner diameter of the sampling nozzle and the total pressure pipe and / or the static pressure pipe connected thereto are the same.

[0016] 8. A flow rate detection system, comprising: two or more Pitot tubes, wherein the two or more Pitot tubes are each independently selected from the Pitot tubes described in any one of items 1 to 7.

[0017] 9. The flow rate detection system as described in item 8, comprising more than one linear detection module, and more than two Pitot tubes are arranged on the linear detection module.

[0018] 10. A flow rate detection system as described in item 9, wherein the linear detection module further comprises: a plurality of connecting tubes, the proximal ends of the plurality of connecting tubes being independently connected to the distal ends of the total pressure pipe and the static pressure pipe of each of the Pitot tubes.

[0019] 11. The flow rate detection system as described in item 10, wherein the linear detection module further comprises: an outer packaging tube, and the plurality of connecting tubes are arranged in the outer packaging tube.

[0020] 12. The flow rate detection system as described in item 11, comprising: more than two linear detection modules.

[0021] 13. The flow velocity detection system according to any one of items 8 to 12, further comprising:

[0022] A pressure difference detection module is used to detect the pressure / pressure difference in each of the total pressure pressure guiding pipe and the static pressure guiding pipe.

[0023] 14. A Pitot tube as described in item 13, wherein the pressure difference detection module includes a pressure sensor, which detects the pressure in the total pressure pipe and the static pressure pipe respectively; or, the pressure difference detection module includes a differential pressure gauge, which detects the pressure difference in the total pressure pipe and the static pressure pipe of each Pitot tube.

[0024] 15. The flow rate detection system as described in item 13 further comprises: a control module, wherein the control module obtains the mathematical average value of the flow rate of each Pitot tube through the detection result of the pressure difference detection module.

[0025] According to the above-mentioned Pitot tube provided by the present application, it is difficult for smoke to be deposited on the sampling nozzle of the C-shaped tube; the opening area facing / backward to the fluid is much smaller than the inner surface area of ​​the sampling nozzle. Even if smoke can be deposited on the inner surface of the sampling nozzle, it can be used for flow rate detection for a longer time compared with the existing direction; especially when the distance between the connecting port and one of the sampling openings of the sampling nozzle where it is located is not equal to the distance between the connecting port and the other sampling opening, the connecting port can be arranged at the upper part. Due to the effect of gravity, even if smoke is deposited, the deposited smoke will be deposited on the lower part of the inner surface of the sampling nozzle, and will not cause blockage to the total pressure pipe and the static pressure pipe, thereby further extending the service life of the Pitot tube; and even if smoke is deposited during long-term use, in addition to introducing high-pressure gas from the far end to clean the deposited smoke particles like the existing Pitot tube, high-pressure gas can also be introduced from one sampling opening of the sampling nozzle, and the high-pressure gas flows out from the other sampling opening. The high-pressure gas has a smaller stroke and a smaller pressure loss, and it is easier to clean the smoke particles. In addition, through the flow velocity detection system of the present application, especially when the flow velocity detection system includes multiple connecting tubes, a pressure / pressure difference detection device can be set at the far end of the connecting tube (the end away from the Pitot tube) to detect the mathematical average of each flow rate required by the "national standard document", and its far end can be closed, which meets the requirements of the detection principle (Bernoulli equation).

[0026] The above description is only an overview of the technical solution of the present application. In order to make the technical means of the present application clearer and to enable those skilled in the art to implement it according to the contents of the specification, and to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are exemplified below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 : Schematic diagram of the existing pitot tube structure;

[0028] Figure 2 : A schematic diagram of the front structure of the existing matrix flow system;

[0029] Figure 3: Left view structural diagram of the existing matrix flow system;

[0030] Figure 4 : A schematic diagram of the front view of the pitot tube in one embodiment of the present application;

[0031] Figure 5 : A schematic diagram of the structure of a pitot tube from the left side in one embodiment of the present application;

[0032] Figure 6 : A schematic diagram of the structure of the sampling port of the pitot tube in one embodiment of the present application;

[0033] Figure 7 : Schematic diagram of the linear detection module structure.

[0034] Description of reference numerals:

[0035] a10, Pitot tube; a11, opening; a12, total pressure pipe; a13, static pressure pipe; a20, total pressure collection pipe; a30, static pressure collection pipe; a40, connecting pipe;

[0036] b10, Pitot tube; b11, sampling nozzle; b11-1, injection opening; b11-2, connection port; b12, total pressure pipe; b13, static pressure pipe; b20, outer tube; b30, connecting tube; b40, pressure detection module;

[0037] r. Deposited smoke and dust. DETAILED DESCRIPTION

[0038] 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 limiting the present application. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present application are deemed to be equivalent replacement methods and fall within the scope of protection of the present application.

[0039] Those skilled in the art should understand that, in the disclosure of the present application, the terms "first", "second", "third", "fourth", "fifth", etc. are only used to distinguish different structures, but do not limit the number, connection relationship, etc. of specific structures; in addition, the directions or positional relationships indicated by "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms cannot be understood as limitations on the present application.

[0040] This embodiment provides a pitot tube b10, such as Figures 4 to 6As shown, including:

[0041] Total pressure pipe b12;

[0042] Static pressure pipe b13;

[0043] A sampling nozzle b11, wherein the sampling nozzle b11 is a C-shaped tube, and the sampling nozzle b11 comprises sampling openings b11-1 at both ends and a connecting port b11-2 located between the two sampling openings;

[0044] Wherein, the distal end of the total pressure conducting pipe b12 and / or the static pressure conducting pipe b13 is connected to the sampling nozzle via the connecting port b11 - 2 .

[0045] In the present application, the "distal end" refers to the end of the Pitot tube close to the injection opening; the "proximal end" is the end opposite to the "distal end", that is, the end of the Pitot tube close to the end for detecting pressure / pressure difference.

[0046] The material of the pitot tube can be polymer materials and / or metal materials. Specifically, for polymer materials, high temperature resistant polyimide (PI), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyamideimide (PAI), polytetrafluoroethylene (PTFE), silicone resins, etc. can be selected; for metal 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. can be selected.

[0047] like Figure 1 As shown, the existing Pitot tube's pressure-conducting tube (total pressure-conducting tube a12 / static pressure-conducting tube a13) has only one opening at the far end, and the gas flow is restricted, resulting in concentrated deposition of smoke particles at the opening a11 of the pressure-conducting tube, which is difficult to remove, easily causing the Pitot tube to be blocked and difficult to use for flow rate detection.

[0048] As this application Figures 4 to 6 As shown, the above-mentioned pitot tube b10 provided by the present application is a C-shaped tube. When used for detection, its two ends are connected, and the gas can flow smoothly, so it is difficult to deposit smoke and dust; in addition, when working, its opening area facing / backward to the fluid is only twice the inner cross-sectional area of ​​the sampling nozzle, and the area where the sampling nozzle can deposit smoke and dust is the entire inner surface of the C-shaped tube, which is much larger than the former. Therefore, compared with the existing pitot tube, the pitot tube provided in this embodiment can be used for flow rate detection for a longer time.

[0049] In addition, even if smoke and dust are deposited when the Pitot tube provided in this embodiment is used for a long time, in addition to introducing high-pressure gas from the remote end to clean the deposited smoke and dust particles like the existing Pitot tube, high-pressure gas can also be introduced from one sampling opening b11-1 of the sampling nozzle b11, and the high-pressure gas flows out from another sampling opening b11-1. The high-pressure gas has a smaller travel distance and a smaller pressure loss, and it is easier to clean the smoke and dust particles.

[0050] Preferably, the sampling nozzle is connected to the distal end of the static pressure pipe b13. Since the opening of the static pressure pipe is facing away from the fluid, a low-pressure vortex zone is easily formed at the opening, so smoke is more easily deposited. By arranging the sampling nozzle b11 on the static pressure pipe b13, the service life of the pitot tube can be extended.

[0051] Of course, more preferably, the sampling nozzles b11 are respectively connected to the distal ends of the total pressure pipe b12 and the static pressure pipe b13. At this time, the two sampling nozzles b11 are arranged opposite to each other so as to be respectively used to face toward and away from the fluid.

[0052] In one embodiment, if Figures 4 to 6 As shown, the distance between the connection port b11 - 2 and one of the injection openings b11 - 1 of the sampling nozzle b11 where it is located is not equal to the distance between the connection port b11 - 2 and another of the injection openings b11 - 1 .

[0053] In the present application, the distance between the connection port b11 - 2 and the injection opening b11 - 1 refers to the minimum distance between all points on the edge of the connection port b11 - 2 and all points on the edge of the injection opening b11 - 1.

[0054] like Figure 6 As shown, the distance between the connecting port b11 - 2 and the upper injection opening b11 - 1 is smaller than the distance between the connecting port b11 - 2 and the lower injection opening b11 - 1 .

[0055] Then, when used for detection, the injection opening b11-1 closer to the connection port b11-2 can be set at the upper part, and the injection opening b11-1 farther from the connection port b11-2 can be set at the lower part, that is, the connection port b11-2 can be set at the upper part, such as Figure 6 As shown, due to gravity, even if smoke is deposited, the deposited smoke will be deposited on the lower part of the inner surface of the sampling nozzle b11, and will not cause blockage to the total pressure pipe b12 and the static pressure pipe b13, thereby further extending the service life of the Pitot tube.

[0056] In one embodiment, if Figure 6As shown, the sampling nozzle b11 and the distal end of the total pressure pipe b12 or the static pressure 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 pipe b12 or the distal end of the static pressure pipe b13 connected thereto are located in the same plane).

[0057] In one embodiment, if Figures 4 to 6 As shown, 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 this embodiment, the two are in the same plane), and the axes of the distal ends of the total pressure conducting tube b12 and / or the static pressure conducting tube b13 connected to the sampling nozzle b11 are parallel to the planes where the two sampling openings are located.

[0058] In one embodiment, the sampling nozzle b11 and the total pressure conducting pipe b12 and / or the static pressure conducting pipe b13 connected thereto have the same inner diameter.

[0059] Based on the above embodiments, the present application also provides a flow rate detection system, such as Figure 7 As shown, it includes: more than two Pitot tubes b10, and the more than two Pitot tubes b10 are each independently any one of the above-mentioned Pitot tubes b10.

[0060] In one embodiment, the flow rate detection system includes more than one (such as 1, 2, 3, 4, 5 or more) linear detection modules, and more than two of the Pitot tubes b10 are arranged on the linear detection module.

[0061] In the present application, "linear" means that the Pitot tubes b10 are arranged in a "linear" manner, such as a straight line / curve. In the present embodiment, they are preferably arranged in a straight line.

[0062] When there are multiple linear detection modules, for a flue with a rectangular / circular cross-section, etc., the multiple linear detection modules can be arranged in parallel or crosswise, so that multiple Pitot tubes can be set (such as array setting) on ​​the cross-section of the flue to detect the fluid flow rate at multiple points in the flue cross-section, so that the flow rate of the fluid in the flue can be known through the flow rate at each point (such as the mathematical average of the flow rate at each point).

[0063] In one embodiment, the linear detection module further includes: a plurality of connecting tubes b30, the proximal ends (ends close to the Pitot tubes) of the plurality of connecting tubes b30 are independently connected to the distal ends of the total pressure pipe and the static pressure pipe of each Pitot tube.

[0064] For example, in "7 Determination of exhaust velocity and flow rate" 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.

[0065] However, if Figure 2-3 As shown, for the existing matrix flow system, no matter for total pressure or static pressure, the total pressure / static pressure or pressure difference at the summing point is detected after summing up the total pressure pipes / static pressure pipes of multiple Pitot tubes, and the average flow rate measured is:

[0066]

[0067] In this embodiment, the proximal ends of the plurality of connecting tubes b30 are independently connected to the distal ends of the total pressure pipe and the static pressure pipe of each of the pitot tubes, so that the pressure difference of each pitot tube can be independently measured through the proximal ends of the connecting tubes b30, so that the average flow rate can be obtained:

[0068]

[0069] In the above two formulas:

[0070] V1, V2——flow velocity, unit: m / s;

[0071] F——velocity field coefficient;

[0072] C——Pitot tube coefficient;

[0073] Pd——differential pressure signal.

[0074] It can be known that the average flow rate obtained by this embodiment (especially when multiple linear detection modules are included) is the mathematical average of the flow rates required by the "national standard document". It can be known through mathematical deduction that the result V1 of the existing solution is greater than the result V2 that can be detected by this embodiment. That is, the result that can be detected by the existing matrix flow system is greater than the average flow rate required by the "national standard document", and it is impossible to accurately detect the flow rate of the fluid in the flue, etc.

[0075] In addition, when using a Pitot tube for flow velocity detection, the Bernoulli equation used requires the proximal end to be closed. In the existing scheme, regardless of the detection of total pressure or static pressure, the total pressure / static pressure openings of each Pitot tube are connected. Therefore, the existing matrix flow system does not fully meet the requirements of the Bernoulli equation, and it itself cannot be used to accurately detect flow velocity.

[0076] Therefore, compared with the existing matrix flow system, the solution provided in this embodiment can set a pressure / pressure difference detection device at the far end of the connecting pipe b30 (the end away from the Pitot tube) so as to detect the mathematical average of each flow rate required by the "national standard document", and its far end can be closed, which meets the requirements of the detection principle (Bernoulli equation).

[0077] In one embodiment, if Figure 7As shown, the linear detection module further includes: an outer package tube b20, and a plurality of the connecting tubes b30 are arranged inside the outer package tube.

[0078] Specifically, the proximal end of the connecting pipe b30, the total pressure pipe b12 of the Pitot tube b10, and the distal end of the static pressure pipe b13 can be connected to the side wall of the outer tube b20 through flanges, thereby realizing the connection between the connecting pipe b30 and the total pressure pipe b12 / static pressure pipe b13.

[0079] In one embodiment, the flow rate detection system further includes: a pressure difference detection module, which detects the pressure / pressure difference in each of the total pressure pressure guiding pipe and the static pressure guiding pipe.

[0080] Specifically, the pressure difference detection module includes a pressure sensor, and the pressure sensor detects the pressure in the total pressure pipe and the static pressure pipe respectively.

[0081] In addition, the pressure difference detection module can also include a differential pressure gauge, which detects the pressure difference between the total pressure conducting pipe b12 and the static pressure conducting pipe b13 of each Pitot tube b10.

[0082] like Figure 7 As shown, the pressure difference detection module can specifically detect the pressure / pressure difference through the far end of the connecting pipe b30.

[0083] In one embodiment, the flow rate detection system further includes: a control module, which obtains the mathematical average value of the flow rates of each Pitot tube through the detection result of the pressure difference detection module.

[0084] Regarding the control module, it can include a controller (such as a single chip microcomputer, etc.), so that the average flow rate (V2) can be obtained through the above formula according to the detection data (pressure / pressure difference) of the pressure difference detection module.

[0085] Of course, the control module can also include an output unit (such as a display screen, a speaker, etc.) to output the average flow rate.

[0086] 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 inner pipe such as the flue, so as to detect the pressure in the pipe while detecting the flow rate, that is, to detect the two items specified in the "national standard document" at the same time.

[0087] Regarding the pressure detection module b40, it can be specifically as follows Figure 7 As shown, a pipe is shown, and a pressure sensor is connected to the upper end of the pipe for pressure detection; a pressure sensor can also be built into the pipe for pressure detection.

[0088] 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 merely illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present application, all of which belong to the scope of protection claimed in the present application.

Claims

1. A pitot tube, wherein: include: Total pressure pipe; Static pressure pipe; A sampling nozzle, the sampling nozzle is a C-shaped tube, and the sampling nozzle includes sampling openings at both ends and a connecting port located between the two sampling openings; Wherein, the distal end of the total pressure guiding pipe and / or the static pressure guiding pipe is connected to the sampling nozzle via the connecting port.

2. The Pitot tube according to claim 1, wherein: The distal end of the static pressure pipe is connected with the sampling nozzle; Preferably, the distal ends of the total pressure conducting pipe and the static pressure conducting pipe are respectively connected with the sampling nozzles, and the two sampling nozzles are arranged back to back.

3. The Pitot tube according to claim 1, wherein: The distance between the connecting port and one of the injection openings of the sampling nozzle where the connecting port is located is not equal to the distance between the connecting port and another injection opening; Preferably, the sampling nozzle and the distal end of the total pressure pipe or the static pressure pipe connected thereto are located in the same plane; More preferably, the planes where the two sampling openings of the sampling nozzle are located are parallel to each other or located in the same plane, and the axis of the distal end of the total pressure pipe and / or the static pressure pipe connected to the sampling nozzle is parallel to the planes where the two sampling openings are located.

4. The Pitot tube according to claim 1, wherein: The sampling nozzle has the same inner diameter as the total pressure pipe and / or the static pressure pipe connected thereto.

5. A flow rate detection system, wherein: include: Two or more Pitot tubes, each of which is independently selected from the Pitot tubes according to any one of claims 1 to 4.

6. The flow rate detection system according to claim 5, wherein: It comprises more than one linear detection module, and more than two Pitot tubes are arranged on the linear detection module.

7. The flow rate detection system according to claim 6, wherein: The linear detection module further comprises: a plurality of connecting tubes, the proximal ends of the plurality of connecting tubes being independently connected to the distal ends of the total pressure conducting tube and the static pressure conducting tube of each of the pitot tubes; Preferably, the linear detection module further comprises: an outer packaging tube, and the plurality of connecting tubes are arranged in the outer packaging tube.

8. The flow rate detection system according to claim 7, wherein: include: More than two linear detection modules.

9. The flow velocity detection system according to any one of claims 5 to 8, wherein: Also includes: A pressure difference detection module, the pressure difference detection module detects the pressure / pressure difference in each of the total pressure pressure pipe and the static pressure pressure pipe; Preferably, the pressure difference detection module includes a pressure sensor, which detects the pressure in the total pressure pipe and the static pressure pipe respectively; or, the pressure difference detection module includes a differential pressure gauge, which detects the pressure difference in the total pressure pipe and the static pressure pipe of each Pitot tube.

10. The flow rate detection system according to claim 9, wherein: Also includes: A control module is used to obtain a mathematical average of the flow rates of each Pitot tube through the detection result of the pressure difference detection module.

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