Research On The Optimization Methods Of Online Detection System For Odor Gas

Odor directly affects people's quality of life and physical and mental health,so the odor detection has become an important part of environmental protection.The on-line detection instrument can effectively analyze the composition and concentration of odor gas,which is not only an important tool for environmental governance,but also an important basis for environmental protection.The main content of this paper is to optimize the existing problems of odor detection instruments to realize more rapid,accurate and low concentration detectionIn this paper,the basic theory of gas chromatography and the basic principle of on-line detection are studied and we analyze the composition and characteristics of the on-line detection system.the defects of the existing on-line detection system are summarized and the optimization method,the research content and the experimental scheme of the system are put forward.In the optimization of the system hardware,the gas circuit and the hardware circuit of the gas pre-concentration device based on the principle of thermal desorption are studied and we propose a dual range measurement method for normal measurement and concentration measurement to reduce the detection limit.The automatic sampling system based on the six way valve is designed,which reduces the influence of the change of the carrier gas flow rate on the measurement.We have completed the programmable gain signal acquisition system to improve the resolution.The heating mode is simulated by COMSOL and the method of mufti-point measurement and local heating is selected to complete the design of temperature control system.At last,the integration of control circuit and the expansion of hardware resources are carried out.In the aspect of software system optimization,it can be divided into the serial screen program design and the lower computer program optimization,which can achieve a good human-computer interaction.In the lower computer software design,according to the characteristics of the noise in the system,the SG digital filter is selected and the optimal parameters are determined through experiments.we consider the factors such as the slope,the amplitude and the noise of the chromatographic peaks and propose a peak recognition algorithm which is suitable for the lower computer.The qualitative and quantitative analysis methods and self calibration procedures are determined and the standard curves of threekinds of gases are obtained through experiments.We have developed the data storage,historical data browsing and other file management functions,so that the software function of the system has been expanded and improved.Based on the optimization of system hardware and software,the experimental study is carried out.The stability and repeatability of the system are described in detail.The effects of temperature,flow rate and sample volume on the measurement results were analyzed with the experimental data.We determine the optimal operating conditions for the separation of benzene and toluene mixed gas by a uniform experimental method.The experimental results show that the optimal chromatographic separation temperature is 50 ?,the carrier gas flow rate is 3mL/min;the standard deviation of the system is 0.53mV;the relative standard deviation is about 1%;and the minimum detection limit of the system is 50 ppb.