Abstract: Two series of a 4.0 MM TPY residue hydrotreating unit have experienced three times catalyst change since the first start-up. In December 2018, the second series replaced FRIPP catalysts. In December 2019, the first series replaced RIPP catalysts. In April 2020, FRIPP catalysts were used again in the second series. During the process of increasing the residuum blending amount after the first two times of catalyst change,when the reaction temperature was about 360 ℃ and the residue ratio of feedstock was more than 76%,Oil-water emulsification occurred in the cold high pressure separator, which brought great danger to the safety production of the unit. The reason of emulsification may be that macromolecular asphaltene would undergo side chain scission reaction when the hydrogenation reaction temperature and the reaction depth were not enough, forming smaller and more polar asphaltene, and the combination of smaller and more polar asphaltene with water to form a more stable emulsion. The average reaction temperature was raised to 370 ℃ before the residue ratio was raised to 76%, which can effectively avoid the occurrence of oil-water emulsification in the cold high pressure separator.

Key words: residue hydrotreating unit, cold high pressure separator, oil-water emulsification, start-up process, reaction temperature, residue ratio

摘要： 某4.0 Mt/a渣油加氢装置两个系列首次开工至今历经3次换剂,2018年12月二系列更换中国石油化工股份有限公司大连石油化工研究院(FRIPP)催化剂,2019年12月一系列更换中国石油化工股份有限公司石油化工科学研究院(石科院)催化剂,2020年4月二系列再次使用FRIPP催化剂。在前两次换剂开工后提高渣油掺炼量的过程中,当反应温度在360 ℃左右、掺渣比超过76%时都遇到冷高压分离器(冷高分)油水乳化问题,给装置安全生产带来隐患。初步判断乳化原因可能是大分子的沥青质在加氢反应温度不够、反应深度不足时发生断侧链的反应,形成分子更小、极性更强的沥青质分子,极性更强的小分子沥青质与水结合形成更稳定的乳化物。在掺渣比提到76%前将反应平均温度提到370 ℃,可以有效避免冷高分油水乳化现象的发生。

关键词: 渣油加氢装置, 冷高分, 油水乳化, 开工过程, 反应温度, 掺渣比