常压塔顶油气换热器腐蚀原因分析及对策

Cause Analysis and Solutions to Corrosion of Overhead Oil-gas Heat Exchanger of Atmospheric Column

蒸馏装置常压塔顶油气-原油换热器E-102管束泄漏是装置运行的主要风险之一,如不及时发现,将导致石脑油被原油污染,管束泄漏后换热器检修还存在中毒、火灾风险。换热器E-102管束泄漏部位集中在管程进口管板右上部区域,判断油气和水在该区域分布不均。腐蚀形貌为坑蚀,腐蚀原因为铵盐垢下腐蚀。根据腐蚀状况和腐蚀原因,制定了控制E-102管束腐蚀的措施:严格管控电脱盐注水、注剂的氯含量,定期对注水、注剂的氯含量进行检测;有机胺盐和无机铵盐都极易溶于水,可定期将在用管束停运,进行水浸泡操作;联系专业喷嘴公司,在管程进口封头内增加注水喷嘴,实现注水在各管子的均匀分布,提高对盐垢的冲洗效果;研究原油注碱的可行性,在确保下游二次加工装置原料钠含量不超指标的前提下,在原油中注入适量的碱液。

Tube bundle leakage of the overhead oil-gas and crude oil heat exchanger E -102 of the atmospheric column of distillation unit is one of the main risks in unit operation.If it is not found in time, the naphtha will be contaminated by crude oil.Also there are poisoning and fire risks in the maintenance of heat exchanger if the tube bundle leaks.The tube bundle leakage of heat exchanger E -102 mainly occurred in the upper right area of tube plate at pipe inlet, and it was judged that oil -gas and water were unevenly distributed in this area.The corrosion morphology was pitting corrosion, and the reason was the under -deposit corrosion of ammonium salt.According to the status and reason of corrosion, some measures were formulated to control the tube bundle corrosion of E -102, including strictly controlling the chlorine content of water injection and agent injection in electric desalting and regularly detecting the chlorine content of water injection and agent injection, regularly putting the tube bundle out of service and soaking it in water because both the organic and inorganic ammonium salts are highly soluble in water, contacting the professional nozzle company to install water injection nozzle in the pipe inlet head to achieve the uniform distribution of water injection in each tube and to improve the flushing effect of salt scale, and studying the feasibility of alkali injection in crude oil to inject a proper amount of alkali liquid into crude oil on the premise of ensuring that the sodium content of raw materials to downstream secondary processing unit does not exceed the standard.