| It is a low-cost application direction that used directly C4 mixed hydrocarbon as cracking feedstock.Becauce mixed C4 hydrocarbons with costly separation technology is byproduct in catalytic cracking and steam pyrolysis of petrochemical production equipment.However,this research progress is slow due to complexity of thermal cracking reaction mechanism.Primary and secondary reactions of mixed C4 hydrocarbon pyrolysis were simulated and calculated by the Materials studio molecular simulation software and Aspen plus process simulation software in this paper.All activation energy,pre-exponential factor and reaction rate constant of secondary free radical elementary reactions that may occur in mixed C4 hydrocarbon were calculated by Materials studio molecular simulation software.Reaction processes of tube cracking furnace were simulated by Aspen plus process simulation software.Firstly,individual pyrolysis reaction mechanisms of n-butane,isobutane,1-butene,2-butene and isobutene were studied.Afterward,primary reaction mechanism,interaction between different radicals in primary reaction and secondary reaction mechanism of mixed C4 hydrocarbon pyrolysis were analyzed.The results indicate that,the products are generated by cycles when the hydrocarbon is subjected to thermal cracking reaction.The cycles are generated by small radical continuous to carry on chain transfer reaction with feedstock and make the feedstock consumed gradually,generating products and small free radicals by the larger free radical decomposition.The reason why free radicals have interact is that little different free radicals carry on chain transfer reaction with other feedstocks and changs the reaction pathway in mixing pyrolysis of different feedstocks.Finally,products distribution of mixed C4 hydrocarbons by simulation calculation and experimental data in the literatures was compared to prove the accuracy of the simulation results. |
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