S Zorb装置进料换热器压力降增大原因分析及对策

Analysis of causes for increased pressure drop of feed heat exchanger in S-Zorb gasoline refining unit and countermeasures

陕西延长石油(集团)有限责任公司延安石油化工厂S Zorb装置自首次开工以来,吸附进料换热器压力降增长过快,严重影响装置长周期稳定运行。停工抢修中发现其积炭严重是造成压力降过快增大的原因。对积炭物分析,硫质量分数10.8%,碳质量分数74.6%,推测引起积炭的原因是原料中氧含量增高造成的。对管输过程各转储点原料的溶解氧数据进行了分析对比,原料溶解氧含量远高于合格原料油所要求的指标,而造成溶解氧增大的主要原因是原料管输过程中上游装置催化汽油原料罐未设置氮封,致使原料与空气接触。通过调整原料管输路线,全封闭直供原料,隔绝了氧溶解至原料油中的途径,减少结焦前驱物的形成,保证了装置的平稳长周期运行。

The pressure drop of feed heat exchanger （ E-101 ） in S-Zorb gasoline refining unit of Yan＇ an Petrochemical Plant of Shaanxi Yanchang Petroleum （Group） Co. , Ltd. had been rising rapidly since it was initially started up, which had a serious impact on the unit＇ s long-term continuous and stable operation. The serious carbon deposition was found in heat exchanger in the shut-down for maintenance, which was the culprit of rapidly increased pressure drop. The carbon content was analyzed, and sulfur content was 10.8% and the carbon content was 74.6%. It was concluded that the carbon deposition was caused by the increasing amount of oxygen in the feedstock oil. The comparative analysis on the dissolved oxygen in the oil at each transmission point of oil pipelines found that the dissolved oxygen in the feedstock of S-Zorb gasoline refining unit was much higher than the design specification. The cause of increased dissolved oxygen was that nitrogen seal was not provided for FCC gasoline tank （G-6306） in the upstream unit which allowed direct contact of oxygen with oil. After adjustment of feedstock oil pipeline routing and closed-loop feedstock supply, the feedstock oil was isola- ted from dissolved oxygen, which has reduced the formation of coking precursor and ensured the long-term sta- ble operation of the unit.