三元可燃混合气体爆炸极限实验及预测方法

Experiment and prediction methods on the explosion limit of the ternary flammable gas mixture

为了控制并预防原油的储存及输运过程中挥发气体造成的安全风险,在20 L球形爆炸容器内开展了由原油中挥发轻烃CH 4、C_(3)H_(8)和C_(2)H_(4)构成的三元可燃混合气体的爆炸极限实验,提出并验证了基于Le Chatelier定律及Chemkin模拟的一维层流预混火焰模型预测三元可燃混合气体爆炸极限的方法。结果表明,三元可燃混合气体爆炸极限始终位于3种纯组分的爆炸极限内,随着某一纯组分增加呈现出接近其爆炸极限的趋势。3种纯组分对爆炸上限的影响要强于对爆炸下限的影响,其中C 2H 4对三元可燃混合气体爆炸上限影响尤为显著。两种预测方法的预测结果均与实验规律性一致。Le Chatelier定律预测混合气体爆炸下限较准确,但对爆炸上限的预测随着C_(2)H_(4)的增加偏差增大,修正后偏差明显减小;Chemkin预测爆炸下限虽存在一定偏差,但在实验偏差的允许范围内,可作为一种预测三元可燃混合气体爆炸下限的新方法。

In order to control and prevent the safety risks caused by volatile gases during the storage and transportation of crude oil,the explosion limit of the ternary flammable gas mixture composed of volatile light hydrocarbons including CH_(4),C_(3)H_(8)and C_(2)H_(4)in crude oil was experimentally investigated in a 20 L spherical explosive device.The experiment was carried out at 20°C and 0.1 MPa,and the method of partial pressure was used to distribute the gases.Taking the rise of pressure over 5%as the criterion for explosion,each group of the experiments was repeated three times.Methods for predicting the explosion limit of the ternary flammable gas mixture based on Le Chatelier’s law and the model of one-dimensional laminar premixed flame in Chemkin are proposed,and the reliability of these two methods is verified by the experiment.The results show that the explosion limit of the ternary flammable gas mixture is always within the explosion limit of these three pure components,which tends to approach the explosion limit of a certain pure component with its increase.The influence of the three pure components on the upper explosion limit is more pronounced than on the lower explosion limit,and the effect of C_(2)H_(4)on the upper explosion limit is particularly obvious compared with the other two pure components.Both methods of prediction are highly consistent with the experimental regularity.The prediction of the lower explosion limit by Le Chatelier’s law is relatively accurate.However,the deviation of the upper explosion limit increases with the raise of C2H4 due to its special characteristics of combustion,and the deviation decreases significantly after the correction of Le Chatelier’s law.Although the prediction of the lower explosion limit by Chemkin,which predicts the lower explosion limit by calculating the laminar burning velocity near the lower explosion limit,desplays a certain deviation,it is within the allowable range of experimental deviations.Therefore,it can be used as a new method to predict the lower explosion limit of the ternary flammable gas mixtures,but the model of one-dimensional laminar premixed flame is not suitable for the prediction on the upper explosion limit.