烷基化装置对C_(4)烯烃组成变化适应性的研究

Adaptability of alkylation device to C_(4) olefin composition

针对C_(4)烷基化原料中异丁烯摩尔分数增加,产品分布、质量变化的现象,采用格度为3的单纯形格点类型创建混料设计,借助热力学方法分析丁烯组成、温度对烷基化反应焓变、绝热温升的影响,探究烷烯比(I/O)、酸烃比(A/O)调整对控制反应温度的作用。结果表明:随异丁烯增加,热效应最大可降低16 kJ/mol左右;随反应温度升高,体系热效应略增,体系热容增大,稳温能力增强;提高烷烯比、酸烃比可有效转移反应热,稳定反应温度。异丁烯烷基化热效应小,低温下便于通过增加烷烯比、酸烃比获得更低的烷基化反应温度,以减小主、副反应热力学优势差异,改善三甲基戊烷选择性,弥补异丁烯烷基化产物辛烷值低的不足,提高烷基化装置适应C_(4)烯烃组成变化的灵活性。

In view of the increase of isobutene mole fraction in C_(4) alkylation raw materials and the change of alkyllation product distribution and quality,mixture design was created by using simplex lattice point type with lattice degree of 3.The influence of butene composition and temperature on reaction enthalpy change and adiabatic temperature rise were analyzed by thermodynamic method,and the control of isobutane-olefin ratio(I/O)and acid-hydrocarbon ratio(A/O)on reaction temperature was explored.The results show that maximum thermal effect reduction could be about 16 kJ/mol with the isobutene increasing in raw material.With the increase of reaction temperature,thermal effect of the system increases slightly,heat capacity of system increases,and the ability of temperature stabilization is enhanced;reaction heat can be transferred effectively and the reaction temperature can be stabilized by increasing I/O and A/O.Isobutylene alkylation has less reaction thermal effect,it is convenient to achieve lower reaction temperature by increasing I/O and A/O at low temperature,so as to reduce the thermodynamic disparity between main and side reactions,improve trimethylpentane selectivity,make up for the deficiency of low octane number from isobutylene alkylation product and enhence the flexibility of alkylation device to C_(4) olefin composition change.