惰化系统极限氧浓度变化规律及监测预警研究

Study on change regulation of limit oxygen concentration and monitoring early warning system for inerting system

为解决高龄油气管罐事故多发且事故后果严重的问题,通过研究惰性气体保护封存技术,提出惰化系统氧浓度等级分级、氧浓度安全裕量设定原则以及极限氧浓度（LOC）测试方法;通过理论与试验相结合的方法,分析CO_2、N_2等2种惰化剂对液化石油气（LPG）爆炸极限与LOC的影响以及抑制机制,并基于此设定预警阈值。结果表明：随着CO_2、N_2量的增加,最大爆炸压力到达时间延时可达7倍,抑爆效果明显,2种惰化剂抑爆机制的不同主要体现在三元碰撞反应;当CO2充入量达到22%或N2充入量达到32%时,LPG处于完全惰化状态;根据试验结果,可设定LPG惰化系统在线和间断氧浓度监测时预警阀值。

In order to solve the problem of frequent accidents with serious consequences involving oil gas pipe tanks at their old age,this paper was aimed at developing an inert gas protection and sealing technology. A method for oxygen concentration classification of inerting system,an oxygen concentration safety margin setting principle and a LOC test method were proposed. The influences of CO2 and N2 on explosion limits of liquefied petroleum gas（ LPG） and LOC were studied theoretically and experimentally.The restraining mechanism was analyzed. Warning thresholds were set. The results indicate that there is a positive correlation between the maximum explosion pressure arrival time and the volume fraction of CO2 or N2,the ratio of the time delayed to that undelayed could reach 7 depending on the fraction,that the mechanisms of explosion suppression of the two inert agents are different,which is mainly reflected in ternary collision reaction,that when the volume fraction of CO2 is 22% or that of N2 is 32%,LPG is completely in a state of inertia,and that the early warning valve values could be set according to the experimental results for LPG inerting system on-line monitoring and oxygen concentration monitoring.