Primary Study Of The Lumped Kinetic Model For Heavy Oil Cracking Into Propylene By Two-stage-riser Technology

An 11-lump kinetic model was established for catalytic pyrolysis of heavy oil, which based on the study of TMP (Two-stage-riser catalytic pyrolysis for Maximizing Propylene yield) technology developed by State Key Laboratory of Heavy Oil Processing.The lump classification, the reaction network and model equations were given by analyzing the technological characteristics and reaction mechanism of TMP technology, with consideration of model precision, suitability and limitations of experiment conditions. Experimental data used to estimate deactivation parameters of catalyst were obtained in a confined fluidized bed reactor and Microactivity Test unit suitable to heavy oil. The kinetic parameters were determined from experimental data obtained in a continuous pilot riser reactor by the Marquart algorithm and genetic algorithm through the stepwise procedure. Runge-Kutta method was used for solving differential equations. The model was verified in a succession of experiments in which the reaction temperature was 580℃and the mass ratio of catalyst to oil was approximately 11. The average relative deviations of the main product yields were less than 10%, which show good agreement with experimental data. In addition, the model was tested by residual analysis, which indicates that the results are reasonable in respect of statistics.Based on the proposed model, the variety of product yields and selectivities with the operating conditions were predicted for single riser as well as the two-stage riser. The results were found to be in accordance with the common mechanism of catalytic pyrolysis. However, there are still limitations in the application of the model due to the semi-empirical of the model parameters. Therefore, several suggestions have been proposed for further improvement of the model.