优化的顶循系统在线清洗方案在DCC分馏塔的应用

Application Of Optimized Top Cycle System On-Line Cleaning Scheme In Dcc Fractionator

随着常压装置原油性质劣化,脱盐脱水困难,催化原料的氮含量和盐含量均有明显升高。同时,降低汽油干点以提高柴汽比,回流返塔温度降低、分馏塔顶温度处于水蒸汽凝结的边缘,分馏塔顶部频繁出现设备失效、操作异常、产品不合格的现象。针对此情况,决定对分馏塔进行水洗,采用传统的水洗方法需停工或大幅降量,造成较大的经济、环保损失。通过分析DCC工艺技术特点,结合现有流程设置,经过工艺核算确定可行性后,开发出优化的利用自身注汽冷凝提供洗塔水的在线清洗方案,并在东方石化DCC装置成功应用多次,效果良好,定期进行在线清洗,减少了垢下腐蚀造成的设备失效;可以对顶循、塔顶腐蚀回路的结盐结垢实现预防性管理。

With the deterioration of crude oil properties in atmospheric unit,it is more difficult for desalination,the nitrogen and salt content of DCC raw material has increased significantly.Meanwhile,the dry point of gasoline is reduced to increase the fuel ratio,the temperature of reflux is reduced,the top temperature of the fractionator is at the edge of water vapor condensation,and the phenomenon of equipment failure,abnormal operation and unqualified products appear more frequently.In view of this situation,it is decided to wash the fractionator,but the traditional method needs to stop or greatly reduce capacity,resulting in great economic and environmental loss.By analyzing the characteristics of DCC technology,combined with the current PID settings,after process calculation to determine the feasibility,a new method using steam from reactor as washing water is debeloped,which has been applied in DCC fractionatorfor many times,proved efficient.By regular on-line cleaning,equipment failures caused by corrosion were reduced.This has successfully realized preventive management of salt formation for top cycle and top system of fractionator.