丙烯精馏塔冷凝器管束泄漏原因分析及对策

CAUSE ANALYSIS AND COUNTERMEASURES AGAINST TUBE BUNDLE LEAKAGE OF CONDENSER IN PROPY-LENE RECTIFICATION TOWER

乙烯装置丙烯精馏塔冷凝器用于丙烯精馏塔塔顶采出气相丙烯的冷凝,运行期间发生管束腐蚀泄漏。2019年大检修期间,装置对换热器进行宏观检查、分析冷却水以及对产生的腐蚀垢污进行化学分析等方法,分析出丙烯精馏塔冷凝器管束泄漏原因。分析结果表明,管程循环水端生物粘泥结垢引起的垢下腐蚀是造成冷凝器管束泄漏的主要原因,壳程工艺介质的腐蚀性较弱,循环水中微生物的腐蚀、氧腐蚀、高温下管束与管板贴胀处应力松弛、管束与管板焊接处缝隙腐蚀对管束泄漏也起到了很大的积极促进作用,丙烯精馏塔冷凝器管束在5种腐蚀形式的共同作用下发生了腐蚀泄漏。提出了对冷凝器定期反冲洗、循环水关键指标监控、冷凝器管程做防腐涂料等防护措施,确保装置长周期安全平稳运行。

The condenser in propylene rectification tower of ethylene plant is used to condense the gas-phase propylene from the top of propylene rectification tower.Corrosion leakage of tube bundle occurred during its operation.During an overhaul in 2019,the causes of the tube bundle leakage of condenser in propylene rectification tower were found out by macroscopic examination of heat exchanger,cooling water analysis and chemical analysis of corrosion fouling.The analysis results showed that the under-deposit corrosion due to the slime biological fouling at tube side circulating water end is the main cause of the tube bundle leakage of condenser,the shell side process medium is less corrosive,the microbial corrosion and oxygen corrosion in circulating water,the stress relaxation at expansion of tube bundle and tube plate at high temperature and the crevice corrosion at the weld between tube bundle and tube plate also play a certain role in promoting the tube bundle leakage,so corrosion leakage occurred in the tube bundle of condenser under the combined action of these five corrosion forms.Some protection measures such as regular backwashing of condenser,key indicator monitoring of circulating water and anticorrosive coating for condenser tube side were put forward to guarantee the long period,safe and stable operation of the plant.