芳烃联合装置模拟与优化(Ⅴ)——二甲苯精馏单元的模拟与优化

二甲苯精馏单元是PX联合装置的重要组成部分,其作用是通过精馏的方法,将来自连续重整、歧化及烷基转移和异构化单元的C8+A原料分离成符合吸附分离单元要求的C8芳烃、歧化及烷基转移单元所需的C9+A。采用Aspen Plus流程模拟软件,对芳烃联合装置中二甲苯精馏单元包括二甲苯塔、邻二甲苯塔、重芳烃塔等塔设备及换热流程进行模拟,通过模型对过程的关键参数如回流比、塔底热负荷、塔压、塔顶采出量等进行综合分析,在各塔产品控制指标(PX纯度和OX纯度)达标前提下,选择最优的操作参数,降低装置能耗,提升装置经济效益。通过对中国石化四套PX装置中的二甲苯精馏单元进行模拟优化,合计实现装置节能效益881万元,并指导装置产品方案的切换,在降低装置能耗和提升装置经济效益的同时,也提高了中国石化芳烃装置二甲苯精馏单元的精细化操作水平。

Simulation and Optimization for Aromatics Complex Plants （V）--Simulation and Optimization for Xylene Rectification Unit

The xylene rectification unit is an important component of an integrated PX plant.The role of the unit is to separate C8＋A from the continuous reforming,the disproportionation,and the transalkylation and isomerization units to C8 arene meeting the requirements of the adsorption stripping unit and C9＋A needed by the disproportionation and transalkylation units.Using the Aspen Plus process simulation software,technicians simulated the equipment and heat exchange processes of the xylene rectification units of an integrated arene plant,including the xylene column,the o-xylene column,and the heavy arene column.With the help of models,they analyzed the key parameters of processes such as reflux ratio,heat load at column bottom,column pressure,and top recovery.When ensuring all product indices of each column （PX purity and OX purity） are up to standard,the optimum operating parameters were selected to reduce the arene plant＇s energy use and raise the plant＇s economic efficiency.The simulation and optimization for the xylene rectification units of Sinopec＇s four PX plants has brought the company 8.81 million yuan in benefits from energy saving.The sim- ulation results have also been used to assist in the switching of product schemes for the plants ,thus helping improve the operation of the xylene rectification units of Sinopec＇s arene plants ,while simultaneously reducing the plants＇ energy consumption and increasing the plants＇ economic efficiency. Keywords] xylene rectification ; process simulation ; model ; optimization ; tapping potential to increase efficiency