Research And Realization Of Ultrasound Sewage Flow Measurement Method

This paper describes an innovative design of an ultrasonic flowmeter for measuring sewage in pipelines,which is mainly used to solve the problem of low accuracy of time difference method for measuring sewage flow.A mathematical model for the movement of sewage containing impurities in pipelines was established in this paper,and FLUENT was used to simulate the movement of sewage containing impurities in pipeline.A method was used to determine the characteristic wave of echo signal by counting the amplitude ratio of echo signal at each flow;the limiting filter algorithm was used to reduce the influence of random interference on flow measurement accuracy.On the basis of the above theoretical research,the hardware and software of dual-channel ultrasonic flowmeter based on TDC-GP30 timing chip and MSP430F5438A chip was designed and manufactured.The FLUENT simulation results show that when the volume concentration of impurities in sewage is less than 1%,the larger particle size of impurities in the pipeline flow(less than100 microns),the greater influence of impurities on the flow coefficient k of small flow points.When the flow rate is more than 60m~3/h in the pipeline,the mean flow coefficient k can be used to the flow calculation.When the flow rate is less than 60m~3/h in the pipeline,the mean flow coefficient k cannot be used to the flow calculation.The results of 20 experiments at six different flow was analyzed in Nanchang Industry,Trade and Water Industry Co.,Ltd.The experimental results show that when the threshold voltage is set between 400mV and 450mV,the system can accurately determine the third wave of the echo signal as the characteristic wave.The experimental results of 100 times for 10m~3/h flow have been completed in Nanchang Industry,Trade and Water Industry Co.,Ltd.The experiment results show that limited filter algorithm can effectively reduce the impact of random interference on flow measurement accuracy.The calibration experiment of ultrasonic flowmeter has been completed in Nanchang Industry,Trade and Water Industry Co.,Ltd.The experiment results show that when the sewage flow rate is less than 40 m~3/h in the pipeline,the indication error of the prototype is more than 2%,but when the sewage flow rate is between 40m~3/h and 300m~3/h in the pipeline,the indication error of the prototype is less than 2%,which show that the developed ultrasonic flowmeter basically meets the requirements of the requirement.The principle and technology of the ultrasonic flowmeter described in this paper,which can be used to develop large-diameter sewage ultrasonic flowmeter with impurity particle size less than 100um and volume fraction less than 10%.For example,measure the sewage discharged from the heating pipe.The results of this project will make some contribution to the development of ultrasonic flowmeter.