加工高酸原油的常压塔塔顶挥发线腐蚀及防护

Corrosion and protection of atmospheric distillation tower overhead linefor processing high acid crude oil

某加工高酸原油的常减压装置的常压塔塔顶(常顶)挥发线,在线腐蚀探针监测数据长时间超过控制指标,检修发现常顶挥发线有较多蚀坑减薄部位,存在腐蚀泄漏风险。通过分析定点测厚情况、探针腐蚀速率、探针腐蚀垢物、常顶含硫污水腐蚀介质,结合常顶挥发线中介质流速的计算,识别出两个加剧腐蚀过程的主要因素:常顶挥发线介质中存在浓度高达390~600 mg/L的多种小分子有机酸,以及塔顶介质的高流速。针对常顶挥发线的腐蚀问题,采取了两项有针对性的措施:控制常顶石脑油流量不超过150 t/h,以减少腐蚀介质在系统内的积累;优化中和剂的选型,确保中和剂能够有效中和系统中的酸性物质,从而显著降低腐蚀速率。通过实施这些工艺措施,改善了常顶挥发线的腐蚀情况,延长了设备的使用寿命,确保了装置能够长期、稳定、安全地运行。

This study focuses on the serious corrosion problem faced by the overhead line of a certain atmospheric distillation tower for processing high acid crude oil.The online corrosion monitoring data has exceeded the control indicators for a long time,and it has been found that there are many corrosion pits and thinning areas on the overhead line,which poses a risk of corrosion leakage.Through the analysis of fixed-point thickness measurement,probe corrosion rate,probe corrosion scale,and corrosive medium in sulfur-containing wastewater at the top of the tower,combined with the calculation of medium flow velocity in the overhead line,two main corrosion factors that exacerbate the corrosion process are identified:the multiple high concentration(390-600 mg/L)of small molecule organic acids present in the overhead line medium,and the high flow rate of the medium at the top of the tower.Two targeted measures have been taken to address the corrosion issue of the overhead line.One is to control the flow rate of naphtha at the top of the tower not to exceed 150 t/h to reduce the accumulation of corrosive media in the system.Another is to optimize the selection of neutralizing agents to ensure that they can effectively neutralize acidic substances in the system,thereby significantly reducing the corrosion rate.By implementing these measures,the corrosion of the overhead line of the atmospheric tower has been improved,the life of the equipment has been extended,and the long-term,stable,and safe operation of the unit has been ensured.