Ultrasonic flowmeter for measuring flue gas flow
By designing the air curtain assembly in the ultrasonic flowmeter to form a tangential flow curtain, the problem of low measurement accuracy of the ultrasonic flowmeter in complex flue gas media is solved, and high-precision monitoring of the flue gas flow is achieved.
Patent Information
- Application Number
- CN202422292911.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-19
- Publication Date
- 2025-07-01
- Estimated Expiration
- 2034-09-19
AI Technical Summary
The prior art uses low measurement accuracy when measuring the flue gas flow rate of fixed pollution sources, especially inaccurate under low flow velocity conditions. Ultrasonic flowmeters are rarely used in complex flue gas media, making it difficult to achieve high-precision monitoring.
An ultrasonic flowmeter for measuring flue gas flow was designed, using ultrasonic probes arranged in pairs, each pair of probes including an ultrasonic transducer and a wind curtain assembly. The air curtain assembly forms a tangential flowing air curtain through the air outlet, blocking the front of the detection surface, reducing water vapor and particulate pollution, and achieving heat dissipation of the ultrasonic transducer.
Through the design of the air curtain assembly, the pollution of water vapor and particulate matter in the flue gas on the detection surface is reduced, and the heat dissipation effect of the ultrasonic transducer is improved, thereby improving the measurement accuracy and achieving high-precision monitoring of the flue gas flow.
Smart Images
Figure CN223050692U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of flue gas measurement, and more particularly, to an ultrasonic flowmeter for measuring flue gas flow rate. Background Art
[0002] China has implemented the dual-carbon strategy of carbon peak and carbon neutrality. The establishment of a carbon monitoring method system is the basic premise for achieving the dual-carbon goal. The monitoring of carbon emissions from fixed pollution sources is an important part of it, and the monitoring of flue gas flow rate from fixed pollution sources is an important part of the carbon monitoring of fixed pollution sources.
[0003] Most of the existing flue gas flow rate monitoring methods for fixed sources in China are S-type Pitot tubes based on the differential pressure method, with low measurement accuracy and inaccurate measurement at low flow rates (less than 5 m / s). Therefore, there is an urgent need for an accurate online continuous measurement technology for the flue gas flow rate of fixed sources.
[0004] Ultrasonic flowmeters have high measurement accuracy and are widely used in the measurement of gas flow in natural gas pipelines. However, the fluid medium of flue gas from fixed pollution sources is complex, containing dust particles, water vapor, and high temperature, all of which attenuate the propagation of ultrasonic signals. Therefore, ultrasonic flowmeters applied to complex flue gas flow are still relatively few. Given the complex medium of flue gas from fixed sources, there is an urgent need for a flue gas flowmeter for fixed pollution sources with high measurement accuracy to achieve high-precision monitoring of flue gas flow rate. Summary of the Invention
[0005] The present application provides an ultrasonic flowmeter for measuring flue gas flow rate, which can achieve high-precision monitoring of flue gas flow rate.
[0006] An ultrasonic flowmeter for measuring flue gas flow rate includes a plurality of pairs of ultrasonic probes arranged in pairs. Any one of each pair of ultrasonic probes can be controlled to be a transmitting probe for transmitting ultrasonic signals, and the other one can be synchronously controlled to be a receiving probe for receiving ultrasonic signals.
[0007] The ultrasonic probe includes an ultrasonic transducer and an air curtain assembly. The ultrasonic transducer includes a detection surface for transmitting or receiving ultrasonic signals. The air curtain assembly is provided with an air outlet, and the air outlet is configured to enable an air flow to form an air curtain in front of the detection surface.
[0008] Optionally, the air outlet is set as an annular air outlet, and the annular air outlet surrounds the detection surface.
[0009] Optionally, the air curtain assembly includes a ventilation pipe and a wind plate connected to one end of the ventilation pipe. The ultrasonic transducer is arranged in the ventilation pipe. The wind plate blocks the four peripheral edges in front of the detection surface, and the annular gap between the wind plate and the four peripheral edges of the detection surface forms the annular air outlet.
[0010] Optionally, the ultrasonic probe further includes a circuit board and a transducer fixing tube sleeved in the ventilation pipe. The ultrasonic transducer is fixedly installed at one end of the transducer fixing tube, and a wire connected to the ultrasonic transducer extends out of the ventilation pipe along the transducer fixing tube and is electrically connected to the circuit board.
[0011] Optionally, the ultrasonic probe further includes a shielding box fixedly connected to the end of the transducer fixing tube away from the ultrasonic transducer, and the circuit board is encapsulated in the shielding box.
[0012] Optionally, the circuit board is provided with an ultrasonic generating circuit and an ultrasonic receiving circuit. The peak voltage of the ultrasonic generating circuit is above 500V, and the noise peak-to-peak voltage of the ultrasonic receiving circuit is lower than 5mV.
[0013] Optionally, the ultrasonic probe further includes a flue fixing tube sleeved outside the ventilation pipe. The flue fixing tube is fixedly connected to the ventilation pipe and is also used for fixed connection with the flue.
[0014] Optionally, sound insulation materials are filled between the ventilation pipe and the flue fixing tube.
[0015] Optionally, the frequency of the ultrasonic transducer is 15kHz to 50kHz; and / or
[0016] The encapsulation housing of the ultrasonic transducer is a polytetrafluoroethylene housing.
[0017] Optionally, the ultrasonic flowmeter further includes a fan and an air pipe. The fan is connected to the air curtain assembly through the air pipe and is used to supply air to the air curtain assembly.
[0018] The present application provides an ultrasonic flowmeter for measuring the flow rate of flue gas. Among them, the air discharged from the air outlet of the air curtain assembly forms a tangentially flowing air curtain directly in front of the detection surface. This air curtain can block directly in front of the detection surface, thereby reducing or preventing the pollution of the detection surface by water vapor and particulate matter in the flue gas. At the same time, it can also achieve the heat dissipation of the ultrasonic transducer, which is beneficial to improving the measurement accuracy. Description of the Drawings
[0019] Figure 1 is a schematic diagram of an ultrasonic flowmeter shown in an exemplary embodiment of the present application;
[0020] Figure 2 is a cross-sectional view of an ultrasonic probe shown in an exemplary embodiment of the present application;
[0021] Figure 3 is a front view of the ultrasonic probe. Detailed Embodiments
[0022] Here, in conjunction with the accompanying drawings, the technical solutions in the embodiments (or "embodiments") of the present application will be clearly and completely described. When the following description involves the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.
[0023] If there are terms related to directional indications or positional relationships in the embodiments of the present application (such as up, down, left, right, front, back, inside, outside, top, bottom, center, vertical, horizontal, longitudinal, lateral, length, width, counterclockwise, clockwise, axial, radial, circumferential, etc.), then such terms are only used to explain the relative positional relationships and movement conditions between components in a certain specific posture (as shown in the accompanying drawings); if this specific posture changes, then the directional indication or positional relationship also changes accordingly. In addition, the terms "first", "second", etc. involved in the embodiments of the present application are only for the purpose of convenient description and cannot be understood as indicating or implying relative importance.
[0024] Please refer to Figure 1 , Figure 1 which is a schematic diagram of an ultrasonic flowmeter 100 for measuring flue gas flow shown in an exemplary embodiment of the present application.
[0025] The present application provides an ultrasonic flowmeter 100 for measuring flue gas flow. The ultrasonic flowmeter 100 can be used to measure the flue gas flow of fixed pollution sources, but is not limited thereto.
[0026] The ultrasonic flowmeter 100 includes a control box 10 and a plurality of ultrasonic probes 20 arranged in pairs. The control box 10 is electrically connected to the plurality of ultrasonic probes 20 through a data line L1. The data measured by the plurality of ultrasonic probes 20 can be output to the control box 10 through the data line L1, and the control box 10 processes the data to determine the flue gas flow. The control box 10 is also electrically connected to the plurality of ultrasonic probes 20 through a power line L2 to supply power to the plurality of ultrasonic probes 20. The specific number of the ultrasonic probes 20 is not limited, and any even number can be set.
[0027] Each pair of the ultrasonic probes 20 is connected through a signal line L3. The signal line L3 is used to transmit a control signal. Each pair of ultrasonic probes 20 is synchronously controlled by the control signal, so that one of them serves as a transmitting probe for transmitting ultrasonic signals, and the other serves as a receiving probe for receiving ultrasonic signals. It should be noted that during the flue gas measurement process, in each pair of ultrasonic probes 20, the one that initially serves as the transmitting probe can also serve as the receiving probe subsequently.
[0028] Please refer to Figure 2 and Figure 3 , Figure 2 which is a cross-sectional view of the ultrasonic probe 20 shown in an exemplary embodiment of the present application. Figure 3It is a front view of the ultrasonic probe 20.
[0029] The ultrasonic probe 20 includes an ultrasonic transducer 21 and an air curtain assembly 22. The ultrasonic transducer 21 includes a detection surface 210 for transmitting or receiving ultrasonic signals. When the ultrasonic probe 20 is used as a transmitting probe, the detection surface 210 serves as the transmitting surface. When the ultrasonic probe 20 is used as a receiving probe, the detection surface 210 serves as the receiving surface. The air curtain assembly 22 is provided with an air outlet 220 for discharging air flow, and the air outlet 220 is configured to enable the air flow to form a dynamic air curtain or air curtain in front of the detection surface 210, and the air curtain or air curtain is substantially parallel to the detection surface 210.
[0030] According to the above description, by setting the air curtain assembly 22, the air flow discharged from the air outlet 220 can form a tangentially flowing air curtain in front of the detection surface 210, and the air curtain can block in front of the detection surface 210, thereby reducing or preventing the pollution of the detection surface 210 by water vapor and particulate matter in the flue gas, and at the same time, it can also realize the heat dissipation of the ultrasonic transducer 21, which is beneficial to improving the measurement accuracy of the ultrasonic probe 20.
[0031] The present application does not limit the specific implementation manner of the air curtain assembly 22. For example, a blower can be provided on the side of the detection surface 210, and the air outlet direction of the blower is set to be parallel to the detection surface 210.
[0032] In this embodiment, the air outlet 220 is set as an annular air outlet, and the annular air outlet surrounds the detection surface 210. With this setting, the air outlet directions of the annular air outlet all face the center of the detection surface 210. On the one hand, it can form a stable and reliable air curtain in front of the detection surface 210, and on the other hand, it can also make the air flows from different directions form a countercurrent to take away the heat of the ultrasonic transducer 21.
[0033] As Figure 2 and Figure 3 shown, specifically, the air curtain assembly 22 includes a ventilation pipe 221 and a wind plate 223. One end of the ventilation pipe 221 is provided with an air inlet 222, the other end of the ventilation pipe 221 is connected to the wind plate 223, the ultrasonic transducer 21 is arranged in the ventilation pipe 221, the wind plate 223 blocks the four peripheral edges in front of the detection surface 210, and the annular gap between the wind plate 223 and the four peripheral edges of the detection surface 210 forms the annular air outlet. The air flow can flow from the air inlet 222 to the air outlet 220. When the air flow encounters the wind plate 223, it changes direction and is discharged from the air outlet 220 along a direction parallel to the detection surface 210. With this setting, the ventilation pipe 221 can provide an installation carrier for the ultrasonic transducer 21, and on the other hand, it can also establish an air duct inside the ventilation pipe 221 through the wind plate 223 to realize an air curtain flowing in a preset direction, with a simple structure and low cost.
[0034] In one embodiment, as Figure 2 shown, in order to reduce the influence of the airflow on the ultrasonic transducer 21, the ultrasonic probe 20 further includes a transducer fixing tube 23 sleeved in the ventilation pipe 221 near the air outlet 220. The connection manner between the transducer fixing tube 23 and the ventilation pipe 221 includes but is not limited to flange connection.
[0035] The wire L4 connected to the ultrasonic transducer 21 extends out of the ventilation pipe 221 along the transducer fixing tube 23. The transducer fixing tube 23 is inserted into the ventilation pipe 221 and can be coaxially arranged with the transducer fixing tube 23. The inner diameter of the ventilation pipe 221 is larger than the outer diameter of the transducer fixing tube 23 and also larger than the outer diameter of the ultrasonic transducer 21. The transducer fixing tube 23 can play a role in supporting and fixing the ultrasonic transducer 21 and can also protect the wire L4. The transducer fixing tube 23 can be made of a stainless steel tube to play an electrostatic shielding role.
[0036] The ultrasonic probe 20 further includes a shielding box 24 and a circuit board 25 provided on the outer side of the ventilation pipe 221 and connected to the transducer fixing tube 23. The circuit board 25 is encapsulated in the shielding box 24, and the signal line L3 extends into the shielding box 24 and is electrically connected to the circuit board 25. The shielding box 24 can be made of aluminum metal. The circuit board 25 is placed in the shielding box 24, which can achieve electrostatic shielding and prevent external electromagnetic waves from interfering with the ultrasonic signal.
[0037] Each ultrasonic probe 20 includes a circuit board 25. The circuit board 25 can control the reception and transmission of ultrasonic signals to avoid signal crosstalk between multiple ultrasonic probes 20. The circuit boards 25 of each pair of ultrasonic probes 20 are connected through the signal line L3 to achieve synchronous control of the signals, so that one of them serves as a receiving probe and the other serves as a transmitting probe.
[0038] In one embodiment, the circuit board 25 includes a single-chip microcomputer, an ultrasonic generating circuit, and an ultrasonic receiving circuit. The ultrasonic generating circuit includes a power supply circuit, a connecting resistor, a coupling capacitor, a field effect transistor, a surge protection diode, and a pulse transformer. The power supply circuit provides a primary voltage. The single-chip microcomputer controls the on and off of the field effect transistor to generate a signal with a required frequency. This signal is output as a high-voltage drive signal through the pulse transformer, so that the peak voltage of the ultrasonic generating circuit is above 500V, thereby exciting the ultrasonic transducer 21 to vibrate to generate an ultrasonic signal with sufficient intensity. The peak-to-peak voltage of the original echo signal is 20mv.
[0039] The ultrasonic receiving circuit includes a current limiting resistor, a limiting diode, a coupling capacitor, a standard voltage chip, and a four-channel operational amplifier, which realizes pre-stage amplification, filtering, secondary amplification, and sampling. The peak-to-peak noise is lower than 5mV, and it can receive weak ultrasonic echo signals.
[0040] The single-chip microcomputer is used to control the number of pulses generated by the ultrasonic generating circuit and the transmission period, and is also used to control the ultrasonic receiving circuit to receive ultrasonic signals, so that the two ultrasonic transducers 21 in each pair of ultrasonic heads 20 are in the transmitting and receiving modes according to a certain time sequence. At the same time, the single-chip microcomputer also includes a high-speed analog-to-digital converter for the user to collect ultrasonic echo signals and transmit them to the control box 10 through the data line L1.
[0041] In one embodiment, as Figure 2 shown, the ultrasonic probe 20 further includes a flue fixing pipe 26 sleeved and connected outside the ventilation pipe 221. The flue fixing pipe 26 is fixedly connected to the ventilation pipe 221, and the flue fixing pipe 26 is also used for fixedly connecting to the flue. The flue fixing pipe 26 can protect the ventilation pipe 221 and also realize the connection between the ultrasonic probe 20 and the flue. The flue fixing pipe 26 can be made of stainless steel pipe. The flue fixing pipe 26 and the ventilation pipe 221 are flange-connected, and the inner diameter of the flue fixing pipe 26 is larger than the outer diameter of the ventilation pipe 221.
[0042] In one embodiment, sound insulation cotton can be filled between the flue fixing pipe 26 and the ventilation pipe 221. The sound insulation cotton can play a role in heat insulation and sound insulation to prevent external ultrasonic noise interference.
[0043] In one embodiment, the frequency of the ultrasonic transducer 21 is 15 kHz to 50 kHz. The ultrasonic signals in this frequency band can transmit a long distance in the flue gas containing particulate matter and water vapor and still maintain a strong signal intensity. For example, the frequencies of the ultrasonic transducer 21 are 15 kHz, 20 kHz, 25 kHz, 30 kHz, 40 kHz, 50 kHz. In a specific embodiment, the frequency of the ultrasonic transducer 21 is 25 kHz.
[0044] The material of the encapsulation shell of the ultrasonic transducer 21 is selected as an inert corrosion-resistant material, including but not limited to polytetrafluoroethylene. Polytetrafluoroethylene can not only resist flue gas corrosion, but also ultrasonic waves have a high penetration rate for polytetrafluoroethylene, effectively avoiding the attenuation of ultrasonic signals.
[0045] Please refer to Figure 1 again. The ultrasonic flowmeter 100 further includes a fan 30 and an air pipe 40. The fan 30 is connected to the air curtain assembly 22 through the air pipe 40 for supplying air to the air curtain assembly 22. The number of fans 30 is not limited, and one or more fans 30 can be provided. In this embodiment, there are two fans 30, and each fan 30 supplies air to a part of the air curtain assembly 22. The fan 30 is also connected to the control box 10, and the control box 10 is used by the user to control the start and stop of the fan 30.
[0046] In one embodiment, the control box 10 includes a microcomputer, a display screen, a power module, and a data wireless transmission module. Each ultrasonic probe 20 transmits echo signal data to the microcomputer inside the control box 10. The microcomputer filters, normalizes, interpolates peak points, extracts envelope lines, sets thresholds to determine the ultrasonic transmission time, and calculates the flow rate. The microcomputer can also display the calculated flow rate on the display, and at the same time, it can wirelessly transmit the calculated flow rate to the data terminal.
[0047] The ultrasonic flowmeter 100 provided by this application is applicable to the flow measurement of complex flue gas media containing dust particles, high humidity, high temperature, etc. It can be used for the flue gas flow measurement of various pollution sources from small-diameter industrial pipelines to large-diameter coal-fired flue gas pipelines, with high measurement accuracy and a standard deviation within 5%.
[0048] The above are only the preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this application shall be included within the scope of protection of this application.
Claims
1. An ultrasonic flowmeter for measuring flue gas flow, characterized in that: It comprises a plurality of ultrasonic probes arranged in pairs, wherein any one of the ultrasonic probes in each pair can be controlled to be a transmitting probe for transmitting ultrasonic signals, and the other one can be synchronously controlled to be a receiving probe for receiving ultrasonic signals. The ultrasonic probe includes an ultrasonic transducer and a wind curtain assembly. The ultrasonic transducer includes a detection surface for transmitting or receiving ultrasonic signals. The wind curtain assembly is provided with an air outlet, and the air outlet is configured to enable the airflow to form a wind curtain directly in front of the detection surface.
2. The ultrasonic flowmeter according to claim 1, characterized in that: The air outlet is configured as an annular air outlet, and the annular air outlet surrounds the detection surface.
3. The ultrasonic flow meter according to claim 2, characterized in that: The wind curtain assembly includes a ventilation duct and a wind plate connected to one end of the ventilation duct, the ultrasonic transducer is arranged in the ventilation duct, the wind plate blocks the four edges in front of the detection surface, and the annular gap between the wind plate and the four edges of the detection surface forms the annular air outlet.
4. The ultrasonic flow meter according to claim 3, characterized in that: The ultrasonic probe also includes a circuit board and a transducer fixing tube sleeved in the ventilation tube. The ultrasonic transducer is fixedly mounted on one end of the transducer fixing tube. A wire connected to the ultrasonic transducer extends out of the ventilation tube along the transducer fixing tube and is electrically connected to the circuit board.
5. The ultrasonic flow meter according to claim 4, characterized in that: The ultrasonic probe further comprises a shielding box fixedly connected to an end of the transducer fixing tube away from the ultrasonic transducer, and the circuit board is packaged in the shielding box.
6. The ultrasonic flow meter according to claim 4, characterized in that: The circuit board is provided with an ultrasonic generating circuit and an ultrasonic receiving circuit, the peak voltage of the ultrasonic generating circuit is above 500V, and the noise peak-to-peak voltage of the ultrasonic receiving circuit is lower than 5mV.
7. The ultrasonic flow meter according to claim 3, characterized in that: The ultrasonic probe further comprises a flue fixing pipe sleeved outside the ventilation pipe, the flue fixing pipe is fixedly connected to the ventilation pipe and is also used for being fixedly connected to the flue.
8. The ultrasonic flow meter according to claim 7, characterized in that: The space between the ventilation pipe and the flue fixing pipe is also filled with sound insulation material.
9. The ultrasonic flow meter according to any one of claims 1 to 7, characterized in that: The frequency of the ultrasonic transducer is 15kHz to 50kHz; and / or The packaging shell of the ultrasonic transducer is a polytetrafluoroethylene shell.
10. The ultrasonic flow meter according to any one of claims 1 to 7, characterized in that: The ultrasonic flow meter also includes a fan and an air pipe. The fan is connected to the air curtain assembly through the air pipe to supply air to the air curtain assembly.