催化裂化装置分馏塔顶油气和换热水换热器腐蚀和选材分析

Analysis on corrosion and material selection of oil gas and hot water exchanger on the top of fractionator of FCC unit

调研了近20套催化裂化装置分馏塔顶油气和换热水换热器的设计条件、操作运行及使用情况,发现此位号换热器腐蚀最严重、最复杂。主要表现为管束外侧(油气侧)的垢下腐蚀和冲刷腐蚀。分析了腐蚀介质的来源、换热器的布置形式、工艺条件等,并结合现场应用情况,提出将换热器材质升级为不锈钢,增加操作弹性,并且控制装置进料,避免掺炼污油、连续注水、管束壳程入口采用防冲板等措施,保障了换热器长期安全使用。

The design conditions, operation and using of oil gas and hot water exchanger on the top of fractionator of nearly 20 sets of FCC unit are investigated, and it is found that the corrosion of this heat exchanger is the most serious and complex. It is mainly manifested as underdeposit corrosion and erosion corrosion on the outside of the tube bundle(oil and gas side). By analysing the source of corrosive medium, the layout form of heat exchanger, process conditions, etc., and combined with the field application situation, it is proposed to upgrade the material of heat exchanger to stainless steel, increase the operating flexibility, control the feeding of the unit, avoid blending dirty oil, water inject continuously, and adopt anti impact plate at the inlet of the tube bundle shell side, so as to ensure the long-term safe use of the heat exchanger.