西安石化苯抽提装置运行状况分析

Analysis on operational state of benzene extraction plant in Xi'an petrochemical company

针对450 kt/a苯抽提装置运行过程中存在的问题,如抽提蒸馏塔和溶剂回收塔两塔热量失衡、塔盘温度分布异常及溶剂劣质化,进行了原因分析,通过积液箱补焊、塔盘重装及优化操作参数等一系列措施,得到了有效解决.工业标定及连续80 d运行结果表明：在溶剂比4.2～4.45,T301底温165～ 171℃,T302底温170～ 173℃,白土罐进料温度165～ 175℃操作条件下,白土罐串联使用,酸洗比色、硫含量及结晶点等项目完全满足工业级石油苯的质量指标要求.非芳烃和回收塔顶苯质量分数平均值分别为99.63％和99.9％,苯产品合格率和收率分别在99.9％和99.1％以上.结束了长时间出售不合格品苯的状况,与检修前相比,装置能耗下降22.23 kg标油/t抽提进料,经济效益及节能效果显著.

Aimed at the existing problems during the operation process of the 450 kt/a benzene extraction plant,such as the heat imbalance,temperature distribution anomalies and solvent deterroration,in SINOPEC Xi＇an Petrochemical Company,the causes are systematically analyzed and a series of measures,such as reinstalling tray,repairing welding fluid box and optimizing operating parameters,are taken to resolve problems effectively.The results of calibration and industrial application for 80 days indicate that,two clay-reactors in series are used.Acid washing colorimetric analysis,mass fraction of sulfur,crystallization point and the other tested items can meet the quality requirements of industrial grade petroleum benzene.The average mass fraction of paraffin and benzene are up to 99.73％ and 99.93％,respectively.The yield and the qualified rate of benzene are higher than 99.1％ and 99.9％,respectively.The operating conditions are as follows：4.2-4.5 of solvent ratio,165-171℃ of extractive distillation tower bottom temperature,170-173℃ of solvent recovery tower bottom temperature,165-175℃ of clay pot feed temperature.The situation that Xi＇an Petrochemical Company sells crude benzene for a long term is completely changed.The energy consumption reduces about 22.23 kg bo/t benzene extraction feed compared with that before maintenance.Remarkable economic benefit and energy saving effect are obtained.