加工高含硫原油常减压蒸馏装置的腐蚀监控

Corrosion Monitoring of Atmospheric-vacuum Distillation Unit Processing High-sulfur Crudes

某公司加工原油劣质化、重质化后,常减压蒸馏、催化裂化、焦化、IGCC(整体气化联合循环发电系统)、污水汽提、轻烃回收、加氢等装置腐蚀有所加剧,其中常压蒸馏、催化裂化、IGCC表现最为明显。常顶油气线的点蚀、催化分馏系统的腐蚀开裂已给安全生产带来了极大的安全隐患。通过对腐蚀监测系统数据分析,及时调整腐蚀控制方案,确保原油硫含量提高后,设备腐蚀处于可控状态。通过对两套常减压蒸馏装置各侧线硫分布、设备管线材质评估及其腐蚀速率的变化进行分析,结合RBI(基于风险的检验)评估报告认为:1号常减压蒸馏装置通过2015年大修进行适当改造后,可持续加工硫质量分数不超过1.5%、酸值不超过0.3 mgKOH/g的原油。2号常减压蒸馏装置在硫质量分数不超过2.5%、酸值不超过0.2 mgKOH/g的情况下,装置的腐蚀处于可控状态。

When the company began to process poorer heavier crude oils, the atmospheric-vacuum distillation unit, FCC unit, delayed coking unit, IGCC, sour water stripper, light ends recovery unit and hydrotreating units, etc began to suffer from increased corrosion, especially the atmospheric-vacuum distillation unit, FCC unit and IGCC. The pit corrosion in the oil vapor line in atmospheric overhead and corrosion cracking in the main fractionators of FCC unit had imposed a great safety hazard for the operation. The equipment corrosion was brought under control by analysis of corrosion monitoring system and timely adjustment of corrosion control schemes after the sulfur in crude oil was increased. Through the evaluation of sulfur distribution of sidedraw lines of two atmospheric-vacuum distillation units and equipment materials as well as analysis of variations of their corrosion rates, the RBI （risk based inspection） report concluded that, after revamping in the overhaul in 2015, the 1# atmospheric-vacuum distillation unit could continuously process the crude oils with 1.5% max. sulfur and 0.3 mgKOH/g max TAN. The corrosion is under control for the 2# atmospheric-vacuum distillation unit when the sulfur in crude oil is no greater than 2.5% and the TAN is no higher than 0.2 mgKOH/g.