Wastewater treatment plant to receive industrial wastewater discharged by enterprises in the industrial park of the main pipe diameter is generally more than 600 mm, the water quality is turbid, complex composition, flow rate varies greatly. For this condition, the flow meter in the design selection, the requirements of measuring instruments with good corrosion resistance and large range ratio. Sewage flowmeter turbine flowmeter, electromagnetic flowmeter or orifice plate flowmeter, etc., but such flowmeter need to be installed in the pipeline sensor, pressure loss, easy to wear and tear, short life expectancy, vortex and velocity distribution sensitive. In practice, the sensor is often covered by debris or entangled and affect the normal use, can not provide accurate data.
As the flow measurement point of water intake main is far away from the monitoring center in the project, ultrasonic liquid flow meter is required to have many functions such as on-site display of instantaneous flow rate, cumulative flow rate, operating status, etc., historical data recording and storage, automatic data checking and inspection, diagnosis of operating conditions and fault alarms, etc., of which the most important one is the ability to transmit the signals to the monitoring center. The main thing is to be able to transmit the signal to the monitoring center. Comprehensive practical needs, the design of the ultrasonic liquid flow meter using RS485 interface MODBUS protocol, master-slave Q&A mode will be collected signals uploaded to the monitoring center control station in communication mode.
Our technicians visited the wastewater treatment plant, and after field investigation, we finally helped the customer to select ultrasonic liquid flow meter and insertion electromagnetic flow meter, which solved the limitation difficulties of the project. It has the advantages of high accuracy, large measuring range, no head loss, easy installation and so on, which solves the problem of precise measurement.
Selection of Ultrasonic Liquid Flow Meter
In order to ensure the normal operation of the flow meter, instrument selection is essential. Ultrasonic liquid flow meter according to the transducer installation method can be divided into external clamping ultrasonic flow meter, insertion type ultrasonic flow meter and standard pipe section type ultrasonic flow meter. Ultrasonic flow meter selection is mainly based on the measurement requirements to choose the appropriate flow meter.
Advantages of clamp on ultrasonic flowmeter:
① clamp on ultrasonic flowmeter transducer installed in the pipeline outside, not in direct contact with the measured fluid, there is no transducer corrosion, bonding and other issues
② Measurement, there is no measuring part inside the pipe, no pressure loss, does not change the flow state of the fluid;
③ simple and convenient installation, the pipeline does not need to be cut off, no need to open holes, no need to stop the flow during installation;
④ can be portable use, easy to have doubts about the other flowmeter for comparison.
Shortcomings: ① higher requirements for pipeline conditions, should determine the pipe material, pipe diameter, wall thickness, lining material and thickness, etc.; ② measurement accuracy is relatively low.
Advantages of handheld ultrasonic flowmeter
① handheld ultrasonic flowmeter sensor is used non-contact, attached, simple installation and easy to operate.
② the use of ultrasonic flowmeter clamped on the measured flowmeter pipeline, by comparing the cumulative flow error of the two flowmeter calibration of the flowmeter being checked.
Standard pipe section type ultrasonic flowmeter
The transducer is fixedly installed in accordance with the design of the processed pipe section, and the transducer is directly in contact with the measured fluid. This flowmeter can accurately control the processing accuracy, at the same time can accurately measure the geometric dimensions of the pipe section, and between the two transducers only a single measured medium, so the measurement accuracy is high, but the shortcomings of the installation is troublesome, the need to cut off the flow, cut the pipeline to install, and for the large-diameter pipeline customized price is high, therefore, unless the special requirements are not recommended to use this ultrasonic flowmeter.
