Modification And Optimization Of The Xylene Column In Continuous Reforming Process

The continuous reforming process mainly uses naphtha as raw materials to produce blending components of high-octane gasoline,C8 aromatics as well as rich hydrogen.The product at the bottom of the xylene column of continuous reforming unit of a petrochemical company in Liaoning Province is C9~+heavy aromatics as the blending components of high-octane gasoline.But there is a problem that the dry point of the blending component is more than 205 ~oC,so that it cannot be blended into gasoline.The purpose of this work is to simulate,improve and optimize the xylene column.And the main studies and final achievements are as follows:1.The first step is using the Aspen Plus software to simulate the running states of the xylene column under the pressurized and atmospheric operation conditions.Then after comprehensive consideration,the pressurized operation was selected.The comparison of simulated result with the practical production proves the accuracy and applicability of the simulation model.The second step is modifying the xylene column by adding a side stream.The gas phase withdraw was accepted through comparing the simulated results of different modification schemes.In addition,the best withdrawing position and the optimal flow rate of side stream was determined,so that the qualified gasoline and diesel can be produced to sale.The third step is analyzing and optimizing the heat exchanger network of the modified xylene column,and the optimization results show that the amount of energy consumption could be reduced by 4500 kW with the renovated heat-exchanging mode.Furthermore,there would be substantial low pressure steam and heat water to be generated as heat medium,resulting in the less consumption of the public works.Therefore the aim of saving energy and reducing cost can be achieved.The simulation in this work can provide reference for practical engineering designs.2.According to the simulation results by Aspen Plus,the calculations and selections of the primary devices were implemented.The column assessment was accomplished using the Cup-Tower software.The heat exchangers were selected using the HTRI Xchanger Suite software and consulting the handbook of heat-exchanger and air-cooler,and the pumps were selected based on the simulation results.The equipment selections provide the reliable equipment models for the practical engineering design.