石化企业水冷器腐蚀泄漏原因分析

Analysis of Corrosion Leaks of Water Coolers in Petrochemical Enterprises

将污水进行适当处理回用于循环水系统,是石化企业降低水耗,减少污水外排的有效办法。锦西石化将中水回用到循环水系统后,焦化装置和重催装置多次发生水冷器腐蚀泄漏,影响装置的安全稳定运行。通过对中水回用现场循环水、回用水水质监测分析,以及水冷器检修调查显示:与新鲜水作为补充水的系统相比,中水回用水作为补充水,微生物种类多,系统更富营养化,更适宜微生物的生长繁殖。锦西石化装置水冷器水侧腐蚀的主要原因,是循环水系统异养菌长期超标,以及黏泥滋生引起的垢下腐蚀及微生物腐蚀。同时,水冷器工艺介质泄漏,进而影响循环水水质,使微生物控制及腐蚀控制出现困难。对此,需要加强循环水系统的杀菌措施,在保证循环水处理效果的同时,必须避免水冷器泄漏与水质腐蚀形成的恶性循环。

Reusing recycled sewage in the circulating water system is an effective way for petrochemical enterprises to reduce water consumption and sewage discharge.After recycled water is reused in the circulating water system,multiple corrosion leaks took place to the water coolers of the coking and heavy oil catalytic unit in PetroChina Jinxi Petrochemical Company,posing a threat to the safe and stable operation of the units.The monitoring of quality of the circulating water and recycled water and investigations on water cooler overhaul records show that compared with the systems using fresh water as the replenishing water,recycled water contains a variety of microbes and is more eutrophic and more suitable for the growth and propagation of microbes.The main reasons for the water-side corrosion of the water coolers of Jinxi Petrochemical Company's units are the long-time overgrowth of heterotroph in the circulating water system and the under-deposit corrosion and microbiological corrosion caused by the growth of sludge.In addition,the leak of process fluid in the water coolers affected the quality of the circulating water,making microbe control and corrosion control difficult.To resolve these problems,sterilization must be stepped up for the circulating water system and effort must be made to prevent a vicious circle caused by the leak of the water coolers and water corrosion while ensuring the effect of treatment of the circulating water.