A three-dimensional Pitot tube gas measurement system

Abstract

The present invention discloses a three-dimensional Pitot tube gas measurement system, which includes a flue gas measurement unit and a data processing unit; the data processing unit includes a measurement purge module and a data processing module; the flue gas measurement unit samples the dynamic pressure of the flue gas to be measured through a plurality of pressure tapping holes, and at the same time samples the static pressure and temperature of the flue gas to be measured through a static pressure tapping probe and a temperature sensor and transmits them to the measurement purge module; the measurement purge module includes a differential pressure transmitter, a pressure transmitter and a temperature transmitter. The measurement purge module performs differential pressure sampling on the collected gas dynamic pressure through the differential pressure transmitter, and the measurement purge module directly samples the gas static pressure and gas temperature through the pressure transmitter and the temperature transmitter respectively, and transmits the differential pressure, static pressure and temperature information to the data processing module; the data processing module processes the collected data and calculates the flow velocity and flow rate of the flue gas to be measured.

Description

Technical Field

[0001] The invention relates to a three-dimensional pitot tube gas measurement system. Background Art

[0002] The existing three-dimensional pitot tube gas measurement system consists of a primary measurement unit and a transmission and data processing unit. In this measurement system, the primary measurement unit consists of a three-dimensional pitot tube, a temperature sensor, and a static pressure measuring tube. The transmission and data processing unit consists of six pressure transmitters, a data acquisition module, and a CPU. This measurement system needs to be equipped with six pressure transmitters, which are respectively connected to the five pressure holes of the three-dimensional pitot tube and a flue gas static pressure measuring probe. The three-dimensional pitot tube, static pressure tube, and temperature sensor are arranged separately, resulting in a large number of pressure transmitters, high cost, complex system, cumbersome installation and measurement, and many measurement interference factors. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a three-dimensional Pitot tube gas measurement system with few measurement interference factors and capable of effectively reducing pressure collection components.

[0004] Technical solution: The three-dimensional pitot tube gas measurement system of the present invention comprises a flue gas measurement unit and a data processing unit; the data processing unit comprises a measurement purge module and a data processing module; the flue gas measurement unit samples the dynamic pressure of the flue gas to be measured through a plurality of pressure sampling holes, and at the same time samples the static pressure and temperature of the flue gas to be measured through a static pressure sampling probe and a temperature sensor and transmits them to the measurement purge module; the measurement purge module comprises a differential pressure transmitter, a pressure transmitter and a temperature transmitter, and the measurement purge module performs differential pressure measurement on the collected gas dynamic pressure through the differential pressure transmitter Sampling, the measuring and purging module directly samples the gas static pressure and gas temperature through the pressure transmitter and the temperature transmitter respectively, and transmits the pressure difference, static pressure and temperature information to the data processing module; the data processing module collects and processes the data and calculates the flow rate and flow of the flue gas to be measured; the measuring and purging module also includes a plurality of electric three-way valves, the gas input end of the electric three-way valve is connected to the pressure taking hole, the output end of the electric three-way valve is connected to the pressure differential transmitter, and the pressure taking hole connected to the pressure differential transmitter is switched by the electric three-way valve, so as to measure the pressure difference of different pressure taking holes by the same pressure differential transmitter.

[0005] Among them, the flue gas measurement unit includes a measuring rod. The front end of the measuring rod is a measuring end, and the rear end of the measuring rod is fixedly connected with a rear end box. The measuring rod is connected to the measuring and purging module through the rear end box. It also includes a clamping assembly and a rotating measurement assembly sleeved on the measuring rod. The clamping assembly includes a stabilizing member, a flange, and a locking device that are fixedly connected in sequence. The rotating measurement assembly includes a dial and a pointer. A locking screw is provided on the locking device, and the locking device locks and fixes the measuring rod through the locking screw. The dial is fixedly connected to the locking device, and the pointer is fixedly connected to the measuring rod. When the measuring rod rotates relative to the clamping assembly, it drives the pointer to rotate relative to the dial. The measuring end includes a measuring probe with multiple pressure tapping holes, a static pressure tapping probe, and a temperature sensor. The end face of the measuring probe with the pressure tapping holes is perpendicular to the flue gas flow direction. The pressure tapping holes, the static pressure tapping probe, and the temperature sensor are respectively connected to the interface assembly in the rear end box through a pressure tapping gas pipe, a static pressure tapping gas pipe, and a measuring cable.

[0006] Among them, the measuring probe is an L-shaped measuring probe. The pressure tapping gas pipe, the static pressure gas pipe, and the measuring cable are all arranged inside the measuring rod. The pressure tapping gas pipes are arranged in one-to-one correspondence with the pressure tapping tubes. The static pressure tapping probe is connected to the static pressure gas pipe, and the temperature sensor is connected to the measuring cable.

[0007] Among them, the rear end box is a hollow cavity. The rear end of the measuring rod extends into the rear end box and is fixedly connected to the rear end box. An interface assembly is provided inside the rear end box. The interface assembly includes a quick-connect interface for connecting the gas pipe and an electrical interface for connecting the measuring cable. The pressure tapping gas pipe, the static pressure gas pipe, and the measuring cable are led out from the rear end of the measuring rod and connected to the interface assembly inside the rear end box.

[0008] Among them, the measuring rod passes through the stabilizing member, the locking device, the flange, the dial, and the pointer in sequence. The inner diameter of the stabilizing member is larger than the outer diameter of the measuring rod. When the locking screw is tightened, the measuring rod is locked. When the locking screw is loosened, the measuring rod makes an axial linear motion or rotates around the axis relative to the locking device.

[0009] Among them, the pressure tapping holes include a central pressure tapping hole, paired pitch pressure tapping holes, and paired yaw pressure tapping holes. The central pressure tapping hole is arranged at the center position of the end face of the measuring probe where the pressure tapping holes are provided. The paired pitch pressure tapping holes are symmetrically arranged with the central pressure tapping hole as the center, and the connecting line is parallel to the axial direction of the measuring rod. The paired yaw pressure tapping holes are symmetrically arranged with the central pressure tapping hole as the center, and the connecting line is perpendicular to the axial direction of the measuring rod.

[0010] Among them, the aperture of the pressure tapping hole is 1 - 10 mm.

[0011] Among them, the measuring and purging module further includes a purging interface. The purging interface is connected to the quick-connect socket of the flue gas measurement unit through a purging solenoid valve.

[0012] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: The system of the present invention integrates a three-dimensional Pitot tube, a temperature sensor, and a flue gas static pressure tube to form a four-in-one measuring device for flue gas temperature, pressure, flow rate, and flue gas direction. Compared with the split-type measuring device, the measuring system of the present invention has fewer measuring interference factors and higher measuring accuracy. The system only contains three pressure acquisition elements (one pressure transmitter and two differential pressure transmitters). Compared with the six pressure acquisition elements of the existing measuring system, the number of pressure acquisition elements is reduced by 50%, effectively reducing the production cost of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic structural diagram of an existing three-dimensional Pitot tube gas measurement system;

[0014] Figure 2 is a schematic structural diagram of the three-dimensional Pitot tube gas measurement system of the present invention;

[0015] Figure 3 is a schematic structural diagram of a flue gas measurement unit;

[0016] Figure 4 is a schematic structural diagram of the arrangement of pressure tapping holes of the flue gas measurement unit;

[0017] Figure 5 is a schematic structural diagram of the flue gas measurement unit installed on the flue during measurement;

[0018] Figure 6 is a connection diagram of the dial and the pointer in the rotating measurement assembly. DETAILED DESCRIPTION OF THE INVENTION

[0019] As Figures 2 to 6 shown, the three-dimensional Pitot tube gas measurement system of the present invention includes a flue gas measurement unit and a data processing unit; the data processing unit includes a measurement purge module and a data processing module; the flue gas measurement unit samples the dynamic pressure of the flue gas to be measured through a plurality of pressure tapping holes, and at the same time samples the static pressure and temperature of the flue gas to be measured through a static pressure tapping probe and a temperature sensor and transmits them to the measurement purge module; the measurement purge module includes a differential pressure transmitter, a pressure transmitter, and a temperature transmitter. The measurement purge module performs differential pressure sampling on the collected gas dynamic pressure through the differential pressure transmitter, and the measurement purge module directly samples the gas static pressure and gas temperature through the pressure transmitter and the temperature transmitter respectively, and transmits the differential pressure, static pressure, and temperature information to the data processing module; the data processing module processes the collected data and calculates the flow rate and flow of the flue gas to be measured; the measurement purge module also includes a plurality of electric three-way valves. The gas input end of the electric three-way valve is connected to the pressure tapping hole, and the output end of the electric three-way valve is connected to the differential pressure transmitter. By switching the pressure tapping hole connected to the differential pressure transmitter through the electric three-way valve, the differential pressure of different pressure tapping holes can be measured by the same differential pressure transmitter.

[0020] The flue gas measurement unit includes a measuring rod 3, a clamping assembly, a rotating measurement assembly, and a rear end box 11; the clamping assembly is fixedly installed on the wall of the flue gas pipeline to be measured, the measuring rod 3 sequentially passes through the clamping assembly and the rotating measurement assembly, one end of the measuring rod 3 extends into the flue gas pipeline to sample the flue gas to be measured, the other end of the measuring rod 3 is fixedly connected to the rear end box 11 outside the flue gas pipeline, and the measuring rod 3 transmits the sampled flue gas pressure to an external measurement system through the interface assembly on the rear end box 11; the measuring rod 3 is slidably connected to the clamping assembly, and the measuring rod 3 can move linearly along the axis or rotate around the axis within the clamping assembly, and the rotating measurement assembly is used to measure the rotation angle of the measuring rod 3 relative to the clamping assembly.

[0021] The front end of the measuring rod 3 is provided with an L-shaped measuring probe 1, and the front end of the measuring probe 1 is a spherical or conical structure; the front end of the measuring probe 1 includes five pressure tapping holes, namely a central pressure tapping hole P1, a yaw pressure tapping hole P2, a yaw pressure tapping hole P3, a pitch pressure tapping hole P4, and a pitch pressure tapping hole P5, and the five pressure tapping holes are used to measure the total pressure of the flue gas and the airflow yaw angle. The aperture of each pressure tapping hole is 1-10 mm; the central pressure tapping hole P1 is arranged at the center position of the end face of the measuring probe where the pressure tapping holes are provided, and the yaw pressure tapping holes P2 and P3 are vertically distributed on the upper and lower sides of the central pressure tapping hole P1; the pitch pressure tapping holes P4 and P5 are horizontally distributed on the left and right sides of the central pressure tapping hole P1. Five pressure tapping gas pipes 13 corresponding to the five pressure tapping holes are arranged inside the measuring rod 3, and the pressure tapping holes are connected to the tail end of the measuring rod 3 through the pressure tapping gas pipes 13 and led out from the tail end of the measuring rod 3.

[0022] The rear end box 11 is a hollow cavity, one end of the rear end box 11 is provided with an interface assembly, the interface assembly includes a plurality of quick connectors 12 and electrical interfaces, the measuring rod 3 is connected to the data processing unit through the interface assembly, the other end of the rear end box 11 is fixedly connected to the tail end of the measuring rod 3 through a fastening nut 10 and the tail end of the measuring rod 3 is inserted into the rear end box 11, and the quick connector 12 is connected to the pressure tapping gas pipe 13 led out from the tail end of the measuring rod 3.

[0023] The clamping assembly includes a flange 5. The measuring rod 3 passes through the flange 5 and is coaxial with the flange 5. The measuring rod 3 moves linearly along the axial direction or rotates around the axis relative to the flange 5. A stabilizing member 4 is fixedly provided on one side of the flange 5 close to the front end of the measuring rod 3, and a locking device 7 is fixedly provided on one side of the flange 5 close to the tail end of the measuring rod 3. The measuring rod 3 passes through the stabilizing member 4, the flange 5, and the locking device 7 in sequence, and the measuring rod 3 is coaxially arranged with the stabilizing member 4, the flange 5, and the locking device 7. The inner diameter of the stabilizing member 4 is slightly larger than the outer diameter of the measuring rod 3, which restricts the disturbance of the measuring rod 3 and plays a role in containing and reducing the measuring disturbance. A locking screw 8 is provided on the locking device 7, and the end of the locking screw 8 on the locking device 7 abuts against the outer wall of the measuring rod 3. When the locking screw 8 is tightened, the measuring rod 3 is locked and cannot move. When the locking screw 8 is loosened, the measuring rod 3 can perform linear motion along the axial direction or rotate around the axis relative to the locking device 7.

[0024] The front end of the measuring rod 3 further includes a static pressure tapping probe P6 and a temperature sensor 2. The static pressure tapping probe P6 is used to measure the static pressure of the flue gas. The inside of the measuring rod 3 also includes a static pressure gas pipe and a measuring cable. The static pressure tapping probe P6 is connected to the tail end of the measuring rod 3 through the static pressure gas pipe and is led out from the tail end of the measuring rod 3 and finally connected to the quick connector 12. The temperature sensor 2 is connected to the measuring rod 3 by threading, welding or gluing, and is used to measure the temperature of the flue gas. The temperature sensor 2 is connected to the tail end of the measuring rod 3 through the measuring cable and is led out from the tail end of the measuring rod 3 and finally connected to the electrical interface on the interface assembly.

[0025] The flue gas measurement unit realizes the integration of measuring parameters such as the static pressure, dynamic pressure, total pressure, temperature, and airflow deflection angle of the flue gas through multiple pressure tapping holes, the static pressure tapping probe P6, and the temperature sensor 2 provided on the measuring probe 1. At the same time, the flue gas measurement unit solves the problems of poor structural stability and measurement stability of the existing three-dimensional pitot tube in the flue through the stabilizing member 4; the measuring rod 3 can move axially and rotate around the axis in the flue, so that the flow field parameters at multiple points on the axis can be measured.

[0026] The rotating measurement assembly includes a dial 6 and a pointer 9. The dial 6 is fixedly connected to the locking device 7 by screws, and the pointer 9 is pressed against the measuring rod 3 by screws and is fixedly connected to the measuring rod 3. The pointer 9 can move together with the measuring rod 3. The angle of rotation of the measuring rod 3 can be read from the scale on the pointer 9 and the dial 6, that is, the intersection point of the reference line on the pointer 9 and the scale line on the dial 6, as Figure 6 shown.

[0027] The measurement and purging module includes two differential pressure transmitters, namely differential pressure transmitter S7 and differential pressure transmitter S8. The measurement and purging module also includes a pressure transmitter S9 and a temperature transmitter. The pressure tapping holes P1, P2, P3, P4, P5 on the measurement probe 1 and the static pressure tapping probe P6 (pressure hole) are respectively and correspondingly connected to the output ports T1, T2, T3, T4, T5, T6 of the quick-connect plug 12. The output port T1 is connected to the upper air inlet of the differential pressure transmitter S7. The output port T2 is respectively connected to the lower air inlet of the differential pressure transmitter S7 and the lower air inlet of the differential pressure transmitter S8. The output port T3 is connected to the upper air inlet of the differential pressure transmitter S8. The output port T4 is connected to the upper air inlet of the differential pressure transmitter S8. The output port T5 is connected to the lower air inlet of the differential pressure transmitter S8. The output port T6 is connected to the pressure transmitter S9. The output ports T3 and T4 are respectively connected to the two side air inlets of the three-way valve S10 and then connected to the upper side of the differential pressure transmitter S8. The output ports T2 and T5 are respectively connected to the two side air inlets of the three-way valve S11 and then connected to the lower side of the differential pressure transmitter S8. The pressure data collected by the pressure transmitter S9 and the differential pressure transmitters (S7, S8) are transmitted to the data processing module through cables. The branch purge solenoid valves S16, S18 are respectively connected to the output ports T1 and T6. Solenoid valves (S13, S14, S15, S16, S17, S18) are arranged on the branches connecting each output port (T1, T2, T3, T4, T5, T6) to the pressure and differential pressure transmitters and are simultaneously connected to the purge port S19.

[0028] The data processing module consists of a central processing unit (CPU), a data acquisition circuit board and a touch screen. The data collected by the pressure, differential pressure and temperature transmitters are sent to the data processing module through cables. The data processing module performs arithmetic processing on the collected data and outputs values such as gas pressure, temperature, flow velocity, flow rate, and gas flow deflection angle. The touch display screen displays each value in real time. The data processing module can send purge signals regularly to blow the gas pipeline through controlling an external compressor to prevent the pressure pipe from being blocked. During purging, the branch purge solenoid valves (S13, S14, S15, S16, S17, S18) are closed and the main purge solenoid valve S12 is opened. During measurement, the branch purge solenoid valves (S13, S14, S15, S16, S17, S18) are opened and the main purge solenoid valve S12 is closed.

[0029] The three-dimensional pitot tube gas measurement system of the present invention measures flue gas through the following steps, specifically:

[0030] (1) During measurement, the front end of the measuring rod 3 of the flue gas measurement unit is extended into the flue gas pipeline, and the flange 5 is butted against the flange I14 reserved on the outer side wall of the flue gas pipeline and fixed by bolts;

[0031] (2) Zero point calibration: Switch the three-way valves S10 and S11 to the calibration circuit, make the P1 pressure port face the air flow, rotate the measuring rod 3 until the pressure difference between the P2 and P3 pressure ports is zero, that is, P2 = P3, and read and record the rotation angle;

[0032] (3) According to the rotation angle read in step (2), obtain the flue gas yaw angle of this measuring point;

[0033] (4) Flow velocity measurement: Keep the rotation position of the three-dimensional pitot tube unchanged, switch the three-way valves S10 and S11 to the measurement circuit, and the measurement system automatically reads and records the measured values of the pressure, pressure difference, and temperature measurement elements at this measuring point, that is, (P1 - P2), (P4 - P5), static pressure P6, and flue gas temperature ts;

[0034] (5) Pitch angle θ pi is a function of F1, that is, θ pi = f(F1), The data processing module calculates the pitch angle of the flue gas according to this formula; θ pi The specific relationship between θ and F1 needs to be obtained through wind tunnel calibration, that is, rotate the measuring device in the pitch plane in the wind tunnel to determine the values of F1 at different θ pi ;

[0035] (6) The flue gas flow velocity is calculated by the following formula:

[0036]

[0037] In the formula:

[0038] V Si is the axial velocity of the flue gas at measuring point i, with the unit of meters per second (m / s);

[0039] K c is the conversion factor (constant);

[0040] F 2i is the calibration coefficient of the measuring device, obtained by the wind tunnel calibration method in step (5);

[0041] t s is the flue gas temperature, with the unit of degrees Celsius (°C);

[0042] P s is the static pressure of the flue duct, with the unit of Pascal (Pa);

[0043] B a is the atmospheric pressure, with the unit of Pascal (Pa);

[0044] M s is the molecular weight of the gas, with the unit of kilograms per kilomole (kg / kmol);

[0045] θyi is the yaw angle of the flue gas flow, in degrees (°);

[0046] θ pi is the pitch angle of the flue gas flow, in degrees (°);

[0047] (7) The data processing module calculates the flow velocity of the gas, and the flow velocity multiplied by the cross-sectional area of the flue duct gives the flue gas flow rate, i.e., the flow rate Q = V Si* A, where A is the cross-sectional area of the flue duct.

Claims

1. A three-dimensional Pitot tube gas measurement system, characterized in that: It includes a flue gas measurement unit and a data processing unit; the data processing unit includes a measurement purging module and a data processing module; the flue gas measurement unit samples the dynamic pressure of the flue gas to be measured through multiple pressure tapping holes, and at the same time samples the static pressure and temperature of the flue gas to be measured through a static pressure tapping probe and a temperature sensor and transmits them to the measurement purging module; the measurement purging module includes a differential pressure transmitter, a pressure transmitter and a temperature transmitter. The measurement purging module samples the differential pressure of the collected gas dynamic pressure through the differential pressure transmitter, and the measurement purging module directly samples the gas static pressure and gas temperature through the pressure transmitter and the temperature transmitter respectively, and transmits the differential pressure, static pressure and temperature information to the data processing module; the data processing module processes the collected data and calculates the flow velocity and flow rate of the flue gas to be measured; the measurement purging module also includes multiple electric three-way valves. The gas input end of the electric three-way valve is connected to the pressure tapping hole, and the output end of the electric three-way valve is connected to the differential pressure transmitter. The pressure tapping hole connected to the differential pressure transmitter is switched through the electric three-way valve for the measurement of the differential pressure of different pressure tapping holes by the same differential pressure transmitter; the flue gas measurement unit includes a measuring rod, a clamping assembly sleeved on the measuring rod and a rotating measurement assembly, and a rear end box; the clamping assembly is fixedly installed on the wall of the flue gas pipeline to be measured. The measuring rod passes through the clamping assembly and the rotating measurement assembly in sequence. One end of the measuring rod extends into the flue gas pipeline to sample the flue gas to be measured, and the other end of the measuring rod is fixedly connected to the rear end box outside the flue gas pipeline. The measuring rod transmits the sampled flue gas pressure to the external measurement system through the interface assembly on the rear end box; the measuring rod is slidably connected to the clamping assembly, and the measuring rod can move linearly along the axis or rotate around the axis in the clamping assembly. The rotating measurement assembly is used to measure the rotation angle of the measuring rod relative to the clamping assembly.

2. The three-dimensional Pitot tube gas measurement system according to claim 1, wherein: The front end of the measuring rod is a measurement end, the rear end of the measuring rod is fixedly connected with a rear end box, and the measuring rod is connected to the measurement purging module through the rear end box; the clamping assembly includes a stabilizing member, a flange and a lock connected in sequence; the rotating measurement assembly includes a scale disk and a pointer; a locking screw is provided on the lock, and the lock locks and fixes the measuring rod through the locking screw; the scale disk is fixedly connected with the lock, and the pointer is fixedly connected with the measuring rod. When the measuring rod rotates relative to the clamping assembly, it drives the pointer to rotate relative to the scale disk; the measurement end includes a measurement probe with multiple pressure tapping holes, a static pressure tapping probe and a temperature sensor. The end face of the measurement probe with the pressure tapping holes is perpendicular to the flue gas flow direction. The pressure tapping holes, the static pressure tapping probe and the temperature sensor are respectively connected to the interface assembly in the rear end box through a pressure tapping gas pipe, a static pressure tapping gas pipe and a measurement cable.

3. The three-dimensional Pitot tube gas measurement system according to claim 2, wherein: The measurement probe is an L-shaped measurement probe. The pressure tapping gas pipe, the static pressure gas pipe and the measurement cable are all arranged inside the measuring rod. The pressure tapping gas pipe is arranged corresponding to the pressure tapping pipe one by one. The static pressure tapping probe is connected to the static pressure gas pipe, and the temperature sensor is connected to the measurement cable.

4. The three-dimensional Pitot tube gas measurement system according to claim 2, wherein: The rear end box is a hollow cavity. The rear end of the measuring rod extends into the rear end box and is fixedly connected to the rear end box. An interface component is arranged in the rear end box. The interface component includes a quick-connect interface for connecting an air pipe and an electrical interface for connecting a measurement cable. The pressure-taking air pipe, the static pressure air pipe and the measurement cable are led out from the rear end of the measuring rod and connected to the interface component in the rear end box.

5. The three-dimensional Pitot tube gas measurement system according to claim 2, wherein: The measuring rod sequentially passes through a stabilizing member, a locking device, a flange, a dial and a pointer. The inner diameter of the stabilizing member is larger than the outer diameter of the measuring rod. When the locking screw is tightened, the measuring rod is locked. When the locking screw is loosened, the measuring rod makes an axial linear motion or rotates around the axis relative to the locking device.

6. The three-dimensional Pitot tube gas measurement system according to claim 2, wherein: The pressure-taking holes include a central pressure-taking hole, paired pitch pressure-taking holes and paired yaw pressure-taking holes. The central pressure-taking hole is arranged at the center position of the end face of the pressure-taking hole of the measuring probe. The paired pitch pressure-taking holes are symmetrically arranged with the central pressure-taking hole as the center and the connecting line is parallel to the axial direction of the measuring rod. The paired yaw pressure-taking holes are symmetrically arranged with the central pressure-taking hole as the center and the connecting line is perpendicular to the axial direction of the measuring rod.

7. The three-dimensional Pitot tube gas measurement system according to claim 6, wherein: The aperture of the pressure-taking hole is 1 to 10 mm.

8. The three-dimensional Pitot tube gas measurement system according to claim 1, characterized in that: The measurement and purging module further includes a purging interface, and the purging interface is connected to the quick-connect socket of the flue gas measurement unit through a purging solenoid valve.

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