阅读说明：本技术 具有改进的皮托管连接结构的流速测量装置 (Flow rate measuring device with improved pitot tube connection structure ) 是由 范其元 于 2019-12-01 设计创作，主要内容包括：本发明公开了一种压差流速测量装置,包括流速变送器、皮托管、安装支架。流速变送器中包括连接到测量电路的压力传感器。当皮托管插入载送过程流体流的管道中,压力传感器感测到在流体流经皮托管时产生的压差。连接结构在皮托管与流速变送器之间起到压力传导、结构固定作用。安装支架起到固定皮托管与载送过程流体流的管道的相对位置。(The invention discloses a differential pressure flow velocity measuring device which comprises a flow velocity transmitter, a pitot tube and a mounting bracket. The flow rate transmitter includes a pressure sensor therein that is coupled to a measurement circuit. When a pitot tube is inserted into a pipe carrying a flow of process fluid, a pressure sensor senses a pressure differential that is created as the fluid flows through the pitot tube. The connecting structure plays a role in pressure conduction and structure fixation between the pitot tube and the flow velocity transmitter. The mounting bracket functions to fix the position of the pitot tube relative to the pipe carrying the process fluid stream.)

1. A differential pressure based flow measurement device comprising:

a pressure transmitter having an output related to a flow rate of a process fluid;

a pitot tube configured to be inserted into a pipe carrying a flow of process fluid;

a connecting structure configured between the pressure transmitter and the pitot tube, fixing the positions of the pitot tube and the pressure transmitter and transmitting pressure to the pressure transmitter;

a mounting bracket for fixing the position of the pitot tube relative to a pipe carrying the process fluid flow.

2. The flow rate measurement device of claim 1, wherein the pressure transmitter has two operating states, a measurement state and a blow-back state.

3. The flow rate measurement device according to claim 2, wherein the operating state is switched using a solenoid valve.

4. The flow rate measurement device of claim 1, wherein the pitot tube has at least one airflow-facing opening that is connected to the pressure transmitter, whereby pressure at the airflow-facing opening is applied to the pressure transmitter.

5. The flow rate measurement device of claim 1, wherein the pitot tube has at least one opening facing away from the air flow, the opening facing away from the air flow being connected to the pressure transmitter, whereby pressure at the opening facing away from the air flow is applied to the pressure transmitter.

6. The flow rate measurement device of claim 1, wherein the connection structure comprises at least one connection bracket.

7. The flow rate measurement device according to claim 6, wherein the connection bracket comprises at least one pressure conduction hole, one end of which is connected to the opening facing the gas flow or the opening facing away from the gas flow, and the other end of which is connected to the pressure transmitter.

8. The flow rate measurement device according to claim 6, wherein the connection bracket comprises at least one stop collar arranged with an outer side of the connection bracket.

9. The flow rate measurement device of claim 1, wherein the connection structure comprises at least one fastening nut.

10. The flow rate measurement device of claim 9, wherein the fastening nut comprises at least one fastening ring.

11. The flow rate measurement device of claim 1, wherein the connection structure comprises at least one compression ring.

12. The flow rate measurement device of claim 1, wherein the connection structure comprises at least one support tube.

13. The flow rate measurement device of claim 1, wherein the mounting bracket comprises at least one fastening nut.

14. The flow rate measurement device of claim 13, wherein the fastening nut comprises at least one fastening ring.

15. The flow rate measurement device of claim 1, wherein the mounting bracket comprises at least one compression ring.

16. The flow rate measurement device of claim 1, wherein the mounting bracket comprises at least one support tube.

Technical Field

The present invention relates to measuring the flow rate of a fluid in an industrial process. In particular, the invention relates to pitot tube measurement of flow rate using differential pressure.

Background

Industrial processes employ process variable transmitters to monitor process variables associated with substances such as: solids, slurries, liquids, vapors, and gases in chemical, pulp, petroleum, pharmaceutical, food, and other processing equipment, and the like. Process variables include pressure, temperature, flow, level, turbidity, density, concentration, chemical composition, and other characteristics. Process flow rate transmitters provide an output related to sensed process fluid flow. The output of the flow transmitter can be sent over a process control loop to a control room or the output can be sent to another process device so that the operation of the process can be monitored and controlled.

Due to the material characteristics of industrial processes, pitot tubes can corrode, clog and the like, and need to be replaced or cleaned manually. The convenience of maintenance is an urgent need of field engineers, and common schemes such as the design of separating a pitot tube from a flow velocity transmitter can increase the length of a pipeline, reduce the sensitivity of differential pressure and increase the possibility of leakage. The invention designs an improved pitot tube connecting structure, so that the pitot tube connecting structure has a good balance among functions, measurement, installation, maintenance, manufacture, transportation and cost.

Disclosure of Invention

A differential pressure and flow velocity measuring device comprises a flow velocity transmitter, a pitot tube and a mounting bracket. The flow rate transmitter includes a pressure sensor therein that is coupled to a measurement circuit. When a pitot tube is inserted into a pipe carrying a flow of process fluid, a pressure sensor senses a pressure differential that is created as the fluid flows through the pitot tube. The connecting structure plays a role in pressure conduction and structure fixation between the pitot tube and the flow velocity transmitter. The mounting bracket functions to fix the position of the pitot tube relative to the pipe carrying the process fluid stream.

Drawings

FIG. 1 shows a cross-sectional view of a flow measurement device and process piping of one embodiment of the present invention.

FIG. 2 is a simplified block diagram of a pitot tube and flow rate transmitter in accordance with an exemplary embodiment of the present invention.

FIG. 3 is a mounting diagram of a flow rate transmitter and pitot tube, mounting bracket of an exemplary embodiment of the invention.

FIG. 4A is an assembled cross-sectional view of a flow rate transmitter and a pitot tube of an exemplary embodiment of the invention.

FIG. 4B is an assembled cross-sectional view of a pitot tube and mounting bracket of an exemplary embodiment of the invention.

FIG. 4C is a cross-sectional view of the opening portion of a pitot tube in an exemplary embodiment of the invention.

The names of the components marked in the figures are as follows:

1. a flow velocity transmitter; 11. fastening a nut; 111. a fastening ring; 12. a compression ring; 13. a full-pressure air pipe; 14. a static pressure air pipe; 17. supporting a tube;

1511. an electromagnetic valve 1; 1512. an electromagnetic valve 2; 1513. a solenoid valve 3;

1521. a pressure sensor 1; 1522. a pressure sensor 2; 153. a measurement circuit; 154. a control circuit;

1551. a communication circuit; 1552. a communication cable; 1561. a power source; 1562. a power supply cable;

1611. back-blowing air supply pipe; 1612. an atmospheric pressure conduction tube;

2. a pitot tube; 21. an opening facing the airflow; 22. an opening facing away from the airflow; 23. protecting the tube;

24. connecting a bracket; 241. a limiting ring; 25. a full pressure interface; 26 a hydrostatic interface;

3. installing a flange; 31. fastening a nut; 311. a fastening ring; 32. fastening a nut; 321. a fastening ring; 33. a compression ring; 34. a compression ring; 35. supporting a tube;

4. a flange; 5. a pipeline; 51. the direction of the airflow.

Detailed Description

As stated in the background of the invention, pitot tube based flow rate measurement devices typically operate by creating a pressure differential in a flowing fluid. A differential pressure sensor can be used to sense the differential pressure, and the sensed differential pressure can be correlated to the flow rate of the process fluid. The invention provides a better connection structure in connection with the practical conditions of function, production, transport and installation, which will be described in more detail below.

FIG. 1 is an exemplary diagram of the environment of one embodiment of the present invention showing a process fluid vessel, such as a pipe or enclosed pipe 5, with a flange 4 mounted on the pipe 5. The flange 4 is provided with a mounting flange 3. The pitot tube 2 is fixed on the mounting flange 3, so that an opening 21 facing to the airflow and an opening 22 facing away from the airflow are deeply arranged in the pipeline 5; wherein the tightening nut 31 is one of the tightening fixtures. The end of the pitot tube 2 not extending into the pipe 5 is provided with a flow velocity transmitter 1. The gas flow direction 51 in fig. 1 is the direction of process fluid flow.

Fig. 2 is a simplified block diagram of an exemplary embodiment. The opening 21 facing the gas flow detects the full pressure of the process fluid flow. Full pressure is transmitted to the full pressure pipe 13 through the connecting bracket 24 and the full pressure port 25. The openings 22 facing away from the gas flow detect the static pressure of the process fluid flow. The static pressure is transmitted to the static gas line 14 via the connecting bracket 24 and the static pressure interface 26.

In the flow rate transmitter 1 of the exemplary embodiment shown in fig. 2: the electromagnetic valve 3 is a main switch for back blowing, one end of the electromagnetic valve is connected with the back blowing air supply pipe 1611, and the other end of the electromagnetic valve is connected with the electromagnetic valve 11511 and the electromagnetic valve 21512. The electromagnetic valve 1 is used for switching the state of the full-pressure air pipe 13, wherein one state is a measurement state, and full pressure is transmitted from the full-pressure air pipe 13 to the pressure sensor 11521; the other is a blowback state, and blowback air is transmitted into the full pressure air pipe 13 from the electromagnetic valve 3 and finally discharged from the opening 21 facing the air flow for cleaning the pipeline. Similarly, the electromagnetic valve 2 is used for switching the state of the static air pipe 14, wherein one state is a measurement state, and static pressure is transmitted from the static air pipe 14 to the pressure sensor 11521 and the pressure sensor 21522; the other is a blowback state, blowback air is transmitted into the static air pipe 14 from the electromagnetic valve 3 and finally discharged from the opening 22 which is opposite to the air flow for cleaning the pipeline.

In the flow rate transmitter 1 of the exemplary embodiment shown in fig. 2: the solenoid valves 1, 2, 3 may be any devices for opening and closing a pipeline; it can be solenoid valve, pneumatic valve, manual valve. Pressure sensor 11521 and pressure sensor 21522 may be any device having an electrical characteristic that changes in response to changes in applied pressure; it may be a silicon piezoresistive pressure sensor, a capacitive pressure sensor. The pressure sensor 11521 responds to changes in the pressure differential between the full head 13 and the static head 14, although other techniques, namely dynamic pressure Pd in the direction 51 of the gas flow, are possible. Pressure sensor 21522 is responsive to changes in the differential pressure between hydrostatic gas line 14 and atmospheric pressure Ba introduced through atmospheric pressure conduit 1612, although other techniques may be used.

In the flow rate transmitter 1 of the exemplary embodiment shown in fig. 2: measurement circuitry 153 is coupled to pressure sensor 11521 and pressure sensor 21522 and is configured to provide a sensor output related to the differential pressure described above. The measurement circuitry 153 may be any electronic circuitry capable of providing an appropriate signal related to differential pressure. For example, the measurement circuit 153 may be an analog-to-digital converter, a capacitance-to-digital converter, or any other suitable circuit.

The control circuit 154 of the exemplary embodiment shown in fig. 2 is connected to the measurement circuit 153 and the communication circuit 1551. Control circuitry 154 is adapted to provide a process variable output to communication circuitry 1551 that is related to the pressure sensor output provided by measurement circuitry 153. The control circuit 154 may be a microprocessor or any other suitable device. Generally, control circuitry 154 converts the differential pressure to an output related to the process fluid. The control circuitry 154 may perform compensation, such as using curve fitting techniques or the like, to adjust the relationship between differential pressure and flow rate. Other factors may be used to compensate for flow rate measurements, including compensating for changes due to temperature, sensed process fluid, absolute pressure, and the like. The control circuit 154 may control the solenoid valve 11511 and the solenoid valves 21512, 31513.

The formula for the flow rate Vs in the exemplary embodiment shown in fig. 2 is calculated as follows:

kp: a pitot tube correction factor; ρ s: the density of the air flow; ts: the temperature of the gas stream; ms: molecular weight of the gas stream.

Power supply 1561 of the exemplary embodiment shown in fig. 2 converts the electrical energy of power supply cable 1562 to the power required by measurement circuitry 153, control circuitry 154, and communication circuitry 1551. Flow transmitter 1 communicates with an upper computer via communication cable 1552. The communication cable 1522 may communicate information between the flow measurement device and the host computer using an appropriate protocol. Such as analog signals for the process control system, a fieldbus, or any other suitable protocol. Further, communication cable 1552 may include wireless communication means. Power supply 1561 and power supply cable 1562 may be incorporated with communications circuitry 1551 and communications cable 1552 for providing the necessary power during communications. Such as analog signals for the process control system, POE, or any other suitable technique.

Fig. 3 is an installation scheme of an exemplary embodiment of the present invention. Fig. 4A, 4B, 4C are detailed cross-sectional views of the mounting scheme of the exemplary embodiment shown in fig. 3.

In the exemplary embodiment shown in fig. 3, 4A, 4B, 4C, the clamp rings 12, 33, 34 may be a device with a sealing function or a device with a fixing function or both, and may have a circular or triangular or notched ring shape or any other suitable shape, and the material may be stainless steel or teflon or any other suitable material. The fastening nut 11, the fastening nut 31 and the fastening nut 32 may be a kind of locking device; it may be a cylindrical body with an outer hexagonal inner circular hole, with the top and bottom ends provided with an inner thread and a tightening ring, respectively, with an inner diameter smaller than the inner diameter of the inner thread, or any other suitable means. The support tube 17 and the support tube 35 may be a fixture; it may be of tubular construction, with at least one thread provided with means for fastening a nut or any other suitable means. The attachment bracket 24 may be a quick-connect device that may be a cylinder having a plurality of through holes therein, a retaining ring disposed around the outer edge of the cylinder, or any other suitable device.

In the exemplary embodiment shown in fig. 3, 4A, 4B, 4C, the mounting flange 3 is generally configured on a structural member similar to the flange 4 of fig. 1. The fastening nuts 31 and 32 are respectively arranged on the threads at the two ends of the support pipe 35 on the mounting flange 3. The clamp ring 33 is disposed between the fastening ring 311 and the support pipe 35; the compression ring 34 is disposed between the fastening ring 321 and the support tube 35. The pitot tube 2 passes through the fastening nut 31, the compression ring 33, the support tube 35, the fastening nut 32 and the compression ring 34. When the fastening nut 31 is tightened, the space between the fastening ring 311 and the clamp ring 33 is reduced, and the clamp ring 33 is pressed against the pitot tube 2 to perform a fixing and sealing function. Similarly, when the fastening nut 32 is fastened, the space between the fastening ring 321 and the compression ring 34 becomes smaller, and the compression ring 34 is pressed to be tightly attached to the pitot tube 2, so that the fixing and sealing effects are achieved. Either end of the fastening nut and clamp ring may be used alone or both ends may be used in this exemplary embodiment.

In the exemplary embodiment shown in fig. 3, 4A, 4B, 4C, the connecting bracket 24 is a cylinder, the top surface of which is provided with the protective tube 23 and the side surface of which is provided with the stop collar 241. The stop collar 241 may also be disposed on the protection tube 23 or any other suitable location. The connecting bracket 24 contains two through holes through the top and bottom surfaces. The top surface side of one through hole is provided with an opening 21 facing the air flow, and the bottom surface side is provided with a full pressure interface 25; the other through hole is provided with an opening 22 facing away from the airflow on the top surface side and a static pressure port 26 on the bottom surface side. Other through holes may be included in the attachment bracket 24 for mounting a temperature sensor or any other suitable device.

In the exemplary embodiment shown in fig. 3, 4A, 4B, 4C, the inside of the support tube 17 is arranged on the flow rate transmitter 1, and the connecting bracket 24 of the pitot tube 2 is inserted from the outside until the stop ring 241. The compression ring 12 is disposed between the stop ring 241 and the support tube 17. The tightening nut 11 is tightened from the outside to press the stopper 241 against the support pipe 17, thereby performing fixing and sealing functions. Full-pressure gas pipe 13 is disposed at full-pressure port 25, and static-pressure gas pipe 14 is disposed at static-pressure port 26, so that the pressure at the opening is applied to the pressure sensor.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. The term pitot tube, as used herein, generally refers to a probe inserted into a fluid stream. The differential pressure sensor may be formed by a single pressure sensor or use a plurality of pressure sensors.