Design And Implementation Of Biomass Boiler Monitoring System Based On WeChat Public Platform

The ultrasonic flowmeter(UFM)has many advantages over the traditional flowmeter and is widely used.It has a high accuracy,contains no moving parts and can be applied in large-diameter pipeline.With the popularization of natural gas in China,the ultrasonic gas flowmeter is more and more widely applied.Some countries have a research on ultrasonic gas flowmeter for a long time and can produce multipath UFM with high precision.But the price is very expensive.Our time of research on UFM is less than other countries and only a few companies can provide low-precision ultrasonic gas flowmeter.This paper has analyzed the relative references and research results and designed a six-path ultrasonic gas flowmeter based on transit-time method.It also proposed a practical approach to help the determination of reference wave used in cross correlation algorithm.Besides,some experiments are performed to test the designed UFM.The main contents of this paper include the following aspects:1)A six-path ultrasonic gas flowmeter is designed.Through the analysis of working principle,this paper makes a UFM based on transit-time method.The hardware module consists of two CPU.The MCU is used to control the switch of path and generation of driven pulse.DSP completes the A/D conversion of received ultrasonic signal and data processing because of its higher operating frequency and A/D conversion speed.Two CPU can effectively improve the performance of UFM.Besides,a control program for MCU and data processing program for DSP is designed.The synchronization of two CPU is also completed.2)A practical method to select reference wave by evaluating the average of ultrasonic signals at zero gas velocity is proposed.Ultrasonic wave will be seriously attenuated and distorted when travelling through natural gas.The flow velocity and facing direction of transducer will result in the instability of ultrasonic wave.When cross correlation algorithm is applied,the reference wave plays a key role in the measurement of the differential time of flight(TOF).This paper has proposed a new method to select reference wave.The method established the reference wave by evaluating the average of ultrasonic signals acquired by both upstream and downstream transducer at zero gas velocity.Compared with random reference wave,the averaging reference wave method can improve the computing accuracy and reproducibility of TOF.It is also very helpful to the performance of UFM.3)Experimental system is set up and experiments about flow measurement are carried out.This paper has performed some experiments.According to the simulation results,the gas flow rate is divided into low velocity and high velocity.The experimental results are processed by Gauss-Legendre numerical integration and linear fitting method.This paper also analyzes the experimental results of zero flow,low velocity and high velocity.The results indicate that relative error of the designed UFM is 4%in low velocity and 2%in high velocity.