炼厂的环烷酸腐蚀问题及最新研究动态

回顾了高酸原油加工防腐经验。加工高酸值原油是炼油企业控制成本、提高赢利空间的重要手段,但同时要面临设备腐蚀加剧问题,如高于230℃的高温部位、减压塔内器件、过流部件等腐蚀严重。各炼油企业普遍采取装置适应性改造、材质升级、加强在线腐蚀监测、高温缓蚀剂等技术手段应对高酸值原油腐蚀问题,然而设备腐蚀风险并没有得到彻底控制,由于腐蚀严重而导致的非计划停工仍难以杜绝,因此许多学者持续开展了高温环烷酸腐蚀研究。通过在模拟介质中的实验研究掌握了温度、总酸值、硫含量等因素对高温环烷酸腐蚀的影响,发现硫腐蚀可以部分抑制环烷酸腐蚀。近年来,实际馏分中环烷酸腐蚀和硫腐蚀交互作用得到了更多关注,重点是研究硫腐蚀产物膜在环烷酸腐蚀环境中的作用和机理。发展了旋转圆环实验装置、喷射式实验装置、流经式迷你高压釜、常温高速双相流模拟装置等,从不同角度模拟工况条件,使之更加接近工业生产实际工况。发展了预成膜-后腐蚀的"Challenge(挑战)"实验,用于研究钝化膜在高温环烷酸腐蚀中的行为和特性。环烷酸在馏分中的分布以及对腐蚀的影响也得到了广泛关注。基于机理或者经验数据的腐蚀预测模型已经成为各种炼厂设备完整性管理技术的基础。

Phenomenon and Research Progress of Naphthenic Acid Corrosion in Refinery

Industry experience of processing high Total Acid Number (TAN) crude oil was reviewed. Purchasing and processing crude oil with high TAN is an important means to improve the profit for refinery; however, the crude oil refining unit also suffers from severe naphthenic acid corrosion (NAC). NAC usually happens at the high temperature parts above 230℃, internal parts of vacuum distillation tower and flow components. Many effective methods have been applied to improve the per-formance of refining units against NAC. The methods include improving corrosive adaptability of units, material upgrading, on-line corrosion monitoring, high temperature corrosion inhibitor and so on. However, the risk of corrosion of the equipment has not been completely controlled. Non-planned unit shutdown still occurs occasionally due to the serious corrosion. Therefore, research on high temperature NAC has been continuously carried out for decades. Experimental results of simulated medium revealed effects of temperature, TAN and sulfur content on NAC, and indicated sulfidation corrosion (SC) can partially inhibit NAC. In recent years, the research interest has been gradually turned to the NAC in the real fraction, and the synergistic effect of NAC and SC, focusing on the inhibition effect of sulfur corrosion product film against NAC. Many new experimental devices have been developed, such as the rotating ring, the impingement device, flow-through mini autoclave, and high speed dual phase flow simula-tion device. These devices simulate operating conditions in the real field from different points of view. Challenge (pretreat-corrosion) experiments have been developed to study the behavior and characteristics of passive film in high-temperature NAC environment. The distribution of naphthenic acid in the real fraction has also been widely studied. The corrosion prediction model has been developed and used as the basis for a variety of refinery equipment integrity management technologies.