Development Of High-speed Pulsed Gas Source And Its Performance Evaluation On Vehicle-mounted Methane Detector

The problem of gas leak has become more and more serious because of the widespread use of natural gas.In this way,it is becoming more and more important to do gas inspections.Today,the types of gas detection equipment are numerous with the rapid development of science and technology.Among them,the vehicle-mounted methane detector using TDLAS technology combines the rapidity of the laser methane detector and the mobility flexibility of the automobile.It has many advantages such as high detection accuracy,fast response,anti-interference ability and so on.The response time is a very important technical parameter for vehicle-mounted methane detector using TDLAS technology.The length of the device response time directly affects the response of the device.However,there has been no specific methods for calibrating the response time of a rapid gas detection device.To solve this problem,this paper developed a high-speed pulse gas source that can be used to calibrate the response time of rapid gas detection equipment.This thesis conducts research on the subject through theoretical analysis,the establishment of theoretical models and experimental verification methods.Firstly,a theoretical model for the development of high-speed pulse gas source was established through the theoretical analysis.The parameters of each component of the experimental device are determined through the analysis of the theoretical model.An experimental platform is set up finally.The experimental verification is performed from several aspects such as the design of the program,the specific implementation process,the analysis of the influencing factors and so on.The analysis of the high-speed pulse gas source is carried out from three aspects:the generation method,response time,and application range.The response time of the traditional gas detector is generally a few seconds,while the vehicle-mounted methane detector requires a response time of less than 1 s.There is no detection method with a response time less than 1 s in the current gas detection standard.This paper presents a method for detecting the response time of a gas detector using a high-speed pulse gas source.It can be used to detect the response time of a rapid gas detection device due to the rapidity of the developed high-speed pulse gas source.Especially for vehicle-mounted methane detectors,performance evaluation is performed through this detection method,and different vehicle speeds are calibrated according to the detected response times of the devices.Besides,the applicable conditions and application ranges are determined accordingly.Based on the analysis of the existing international relevant technical standards,the paper designs and implements two kinds of pulsed and vacuum-type pulsed standard gas sources with high-speed changes.Tests have shown that the concentration rise time of both gas sources is not more than 100mS.The two types of pulsed gas sources have been further optimized and are expected to solve the problem of the detection of the response time of current high-speed TDLAS gas detectors.