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Abstract:
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 CH4, C3H8 and C2H4 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 C2H4 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.
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