对浮顶油罐的油气空间进行惰化,是一种新的油罐防火防爆方法.向浮顶油罐一、二次密封间的油气空间中加入氮气,可缩小浮顶油罐的一、二次密封之间环形空间油气的爆炸极限的范围.根据这一原理,通过模型实验对大型双重密封型浮顶油罐的油气空间进行了氮气惰化保护实验研究.实验结果表明油气空间内氮气的体积分数会随着氮气通入时间的增长而逐渐升高,油气的体积分数则逐渐降低.氮气通入开始一段时间,环形空间内氮气的体积分数会迅速上升,油气体积分数迅速下降.但随着氮气通入时间的增长,氮气体积分数的上升和油气体积分数的下降速度都会趋于平缓.另外当入口处氮气流量从27Nm3/h变化到54Nm3/h时,为使油气体积分数下降至油气爆炸下限1％所需氮气持续通入的时间也从300分钟左右下降至200分钟左右.%Vapour deactivation is a new technic in fire and explosion prevention for floating-roof tank. In this paper, according to the thoery of nitrogen deactivation, a test of vapour deactivation in the vapour space of a floating-roof tank which was double sealed was carried out. The test model was set up on the basis of similarity principle in accordance with prototype of the vapour space between primary seal and secondary seal of a ten thousand cubic metres floating-roof tank. The results showed that volume fraction of nitrogen in vapour space increased by nitrogen being injected into the vapour space constantly, while the volume fraction of vapour decreased. Firstly volume fraction of nitrogen increased fast and then gently which was reverse to volume fraction of vapour. If vapour volume fraction of vapour space keep in one percent, the tank was safe. To reduce the vapour volume fraction of vapour space to one percent which was five percent initially, the nitrogen should be injected into vapour space constantly for 300 mintes with flow rate 27 natrue cubic metres per hour. And the flow rate of the nitrogen injected vary from 27 natrue cubic metres per hour to 54 natrue cubic metres per hour, the time for the nitrogen injected reduced from 300 mintes to 200 mintes.
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