What types of wastewater flow meters are available?

Project Overview

Overall China's sewage treatment capacity is low, a considerable portion of untreated sewage is discharged directly or indirectly, seriously polluting the water body, and becoming a prominent problem that harms the environment and ecology and affects people's lives and health. In the process of water environment protection and management, the flow of sewage discharge accurate measurement approved is a very necessary basic work. Water Pollution Prevention and Control Law stipulates that key sewage disposal units shall install automatic monitoring equipment for water pollutant discharge, network with the monitoring equipment of the competent environmental protection department, and ensure the normal operation of the monitoring equipment. Enterprises discharging wastewater should monitor the wastewater they discharge and keep original monitoring records.

Wastewater flowmeter as a kind of automatic monitoring equipment for water pollutant discharge, is an integral part of pollution control facilities. Currently used to measure wastewater flowmeter variety, with more electromagnetic flowmeter and acoustic Doppler flowmeter.

一、Electromagnetic flowmeter

Magnetic inductive flowmeter is the application of the principle of electromagnetic induction, according to the conductive fluid through the applied magnetic field generated by the electric potential to measure the flow of conductive fluids, an instrument. The basic principle is: in general non-conductive materials made of pipes outside, installed a pair of magnetic poles N and S, used to generate a magnetic field. When the conductive fluid flows through the pipeline, because the fluid cuts the magnetic lines of force and produced a magnetic susceptibility to electromotive force, this induced potential by the perpendicular direction of the magnetic poles and the two electrodes lead, when the strength of the magnetic field is unchanged, a certain diameter of the pipeline, this induced potential size is only related to the flow rate, the size of the induced potential will be transmitted to the display instrument, it can be read out the flow rate. Electromagnetic flowmeter has the advantage of very small pressure loss, measurable flow range. The ratio of maximum flow rate and minimum flow rate is generally 20:1 or more, applicable to a wide range of industrial pipe diameter, up to 3m, the output signal and the measured flow rate into a linear, high accuracy. However, its application range is limited, only suitable for full pipe fluid flow; when the flow rate and velocity distribution does not meet the set conditions, will produce a large measurement error; electromagnetic flowmeter signal is relatively weak, the outside world slightly interfere with the accuracy of the measurement can be affected.

二、Doppler ultrasonic flowmeter

Doppler ultrasonic flowmeter uses ultrasonic wave propagation in the water encountered in the suspended matter scattering Doppler effect, through the measurement of the frequency difference between the transmitter wave and the receiver wave to calculate the flow rate, through the pressure sensor to measure the water level, belongs to the "speed - cross-sectional area method" flow indirect measurement device. Doppler ultrasonic flowmeter has the following advantages:

• 1. Cross-sectional flow velocity measurement through a certain inclination of the ultrasonic probe installation, to ensure that the measurement cross-section is an elliptical cross-section, covering the flow velocity of different depths, the results are closer to the cross-section of the flow velocity, and compared with non-contact surface flow velocity measurement methods, the rate of calibration work is less, and the results of the measurement are more accurate;
• 2. High Measurement Accuracy Through the use of selective band Fourier transform signal processing algorithms, millimetre-level velocity resolution can be achieved while maintaining stable measurement results;
• 3. Low power consumption from device selection, circuit design to embedded software design of the entire design system, with advanced power management strategies and scientific work mode switching, to ensure that the flowmeter machine low power consumption, to improve the battery life without charging conditions of the measurement scene;
• 4. Compatible with both full and non-full pipe flow measurements The combination of the velocity-cross section method and the Doppler principle ensures that the meter can be used for all full and non-full pipe flow measurements where turbidity is greater than 20mg/L. The flow meter can be used for all full and non-full pipe flow measurements.

Wastewater treatment plays an important role in cutting pollutant emissions, improving the water environment and promoting the effective use of water resources, and is an important measure to alleviate the scarcity of water resources. In the process of wastewater treatment, the selection of appropriate flow monitoring equipment according to the actual situation is conducive to strengthening the supervision of pollution sources, implementing the total pollutant discharge control and sewage licensing system, preventing pollution accidents, and improving the scientific and informative level of environmental management.