Ultrasonic Methane Detection Technology With Function Of Temperature And Humidity Compensation

Methane is the main component of natural gas,coal mine gas and biogas,it is a high quality fuel gas in the aspect of gas energy,and is also an important raw material in the production of many chemical products and synthetic gases.Methane is flammable and explosive gas.When the content of methane in the air enters the limit of explosion,if a bright fire is encountered,a violent explosion will occur.At present,semiconductor detectors and catalytic sensors are widely used for methane detector on the market.The main problems of these two sensors are short service life,poor stability and high power consumption.Based on this background,it is of great significance to put forward a high efficient and stable detection technology for methane concentration.The transmission speed of ultrasound in different gases is different.Based on this characteristic,the ultrasonic methane concentration detection technology with the function of temperature and humidity compensation is adopted in this paper.The method is based on a single track composed of a pair of ultrasonic probes.One end of the probe is used to transmit ultrasonic waves and the other end of the probe is responsible for receiving ultrasonic signals,and a sound barrier is placed between the transmitting and receiving probes,which is used to reduce the ultrasonic reflection interference.The signal of the receiving probe is amplified by the signal conditioning circuit,and then enters the phase detection circuit,the duty cycle voltage conversion path to realize the phase measurement,and then connects to the single chip microcomputer system for data processing.In this paper,the theoretical analysis is carried out to the influence of ambient temperature and humidity on sound velocity,the mathematical models of gas concentration,sound velocity,phase difference and temperature and humidity are established.This method effectively compensated the influence of environmental temperature and humidity,improved the measurement accuracy,and could work in a wide environment temperature and humidity condition,and had excellent stability.Based on the mathematical models of gas concentration,sound speed,phase difference and ambient temperature and humidity,a single-chip microcomputer data processing software is designed in this paper,and the prototype is tested.The measured results verify that the method achieves better temperature and humidity compensation and has high measurement accuracy.