Abstract:

The processing feedstocks for a 2.5 MM TPY heavy-traffic asphalt unit at a CNOOC refinery are mostly high acid and low sulfur cycloalkyl marine crude oil. Naphthenic acid can cause severe corrosion to the vacuum system under high temperature. Corrosion issues such as the third vacuum line filler and header tank of the unit are prominent, and there is coking phenomenon in the vacuum and high temperature section, which seriously affects the long-term operation of the unit. In order to solve the corrosion problem of the middle and lower fillers of the vacuum tower of the unit, the fillers are replaced with 317L and treated with stainless steel anti-corrosion and anti-coking surface modification technology(CTS), and long-term industrial application testing is conducted. After continuous operation for two years, the maximum and minimum tensile strength of 317L+CTS filler are 11.9% and 9.2% higher than 317L filler, respectively. After continuous operation for three years, there is no significant change in the tensile strength of 317L+CTS filler, and the tensile strength of 317L filler decreases by 16% to 41%. After being treated with CTS technology, the anti-corrosion, anti-coking, and anti-scaling of the filler have been significantly improved. The application of CTS technology in heavy-traffic asphalt unit can effectively reduce by high temperature naphthenic acid corrosion problem, extend the operating cycle, and ensure the safe, stable, and efficient operation of the unit.

Key words: heavy-traffic asphalt unit, vacuum tower, CTS technology, high acid and low sulfur crude oil, anti-corrosion, anti-coking, filler corrosion

摘要：

中国海油某炼油厂2.5 Mt/a重交沥青装置主要加工高酸低硫环烷基海洋原油，因高温环境下环烷酸会对减压系统造成严重腐蚀，该装置减三线填料、集油箱等腐蚀问题突出，同时在减压高温段存在结焦现象，严重影响了装置的长周期运行。为了解决该装置减压塔中下部填料腐蚀问题，更换减压塔中下部填料为317L并进行不锈钢耐蚀抗焦(CTS)技术处理，进行了长周期的工业应用测试。结果表明：连续运行2 a后，317L+CTS填料的最大抗拉强度和最小抗拉强度分别比317L填料高11.9%和9.2%;连续运行3 a后，317L+CTS填料抗拉强度没有明显变化，317L填料的抗拉强度降低16%～41%;CTS技术处理后填料耐腐蚀、抗结焦、抗结垢能力得到明显提高。CTS技术应用于重交沥青装置能够有效减少高温环烷酸带来的腐蚀问题，延长运行周期，保障装置安全、平稳、高效运行。

关键词: 重交沥青装置, 减压塔, CTS技术, 高酸低硫原油, 抗腐蚀, 抗结焦, 填料腐蚀