Research And Application Of The Key Technology Of Fire Early Warning And Monitoring In Gas Station

Gas station is an important supporting unit in the transportation industry and people’s daily life,and it is also recognized as an important place to prevent fire accidents with explosive,flammable,and has a high safety risk factor.With the introduction of charging piles and the rapid increase in non-oil products business,gas stations produce alkane-type flammable gas in the surrounding environment due to volatilization and leakage of oil and gas during operation,as well as refueling(gas)guns,submersible oil pumps(compressors)and other electrical equipment electrical wiring connections in poor contact,cable or equipment insulation aging damage caused by the series fault arc,has quietly become the main factor of fire induction.Conventional detection methods for alkane-type flammable gas(especially methane in gas stations)based on catalytic combustion technology are prone to false alarms and underreporting due to defects such as low measurement accuracy,weak anti-interference ability,easy poisoning and dormancy;Series fault arc detection methods such as arc theory mathematical model,physical feature diagnosis,because the current amplitude is relatively small when the arc occurs,it is easily limited by the characteristics of load current annihilation,concealment and randomness,which is difficult to accurately detect and produce false alarms and underreporting.Therefore,in view of the above two key technical issues-series fault arc type fi re early warning monitoring technology and methane gas type fire early warning monitoring technology,have been targeted for research.The main research contents and results are as follows.The characteristics of the gas station and its potential fire hazards were studied,points out the importance of fire early warning system for timely detection of fire hazards and elimination of fire accidents.Analyze the characteristics and development trends of the current fire warning system for gas stations,and point out that the accurate monitoring of series fault arcs and methane gas has become an important task of fire warning and monitoring for gas stations.The theories and algorithms of the key technology of series fault arc type fire early warning monitoring are studied.The mechanism and related characteristics of the series fault arc in the AC electrical circuit are analyzed.In view of the "zero current" phenomenon and the characteristics of high harmonic phenomena in current waveforms,a series fault arc detection method based on the correlation theory and zero current feature fusion is proposed.This method is based on the low-voltage single-phase AC series fault arc experiment platform built with reference to the UL1699 standard.It collects two periodic currents of the electrical circuit and calculates its proportion coefficient of zero current time,and the maximum correlation coefficient of the normalized absolute value after filtering out low-frequency components.Then the two coefficients are fused by a fuzzy logic processor to obtain the comprehensive characteristic identification coefficient of the series fault arc,it is possible to identify whether there is an occurrence of series fault arc through comparing the deep combination of the coefficient getting before and the proportion coefficient of zero current time with the empirical threshold value.With methane gas in alkanes as the research object,the theories and algorithms of the key technologies of methane gas type fire early warning and monitoring are studied.This thesis analyzes the spectral characteristics of methane gas molecule absorption,determines the basic detection method of dual wavelength NDIR,and puts forward the methane gas early warning monitoring system model based on Kalman filtering algorithm,which improves the accuracy of methane gas detectionThe realization of key technologies for fire early warning and monitoring in gas stations is studied.The technical requirements analysis,hardware design and software process design of the series fault arc type fire warning detector and methane gas type fire warning detector of the gas station were completed,and the signal acquisition,fault identification and control output functions were realized respectivelyExperiments and data analysis of series fault arc type fire early warning monitoring technology and methane gas type fire early warning monitoring technology were carried out The results show that the series fault arc detection method based on the fusion of the correlation theory and zero current feature proposed in this thesis can recognize up to 100%of the series fault arc generated when the load recommended in GB 14287.4 is used in the low-voltage single-phase AC power circuit;the methane gas fire early warning detector designed has a precision of 98.27%,a response time of t90≤30s,a repeatability of no more than 2%,a maximum zero drift of 0.4%FS(FS is the full range of the detector),and a measurement range the maximum drift is 0.8%FS.Eventually,the comprehensive,safe and reliable operation of the fire warning and monitoring system of the gas station is realized,which has practical engineering value.