Abstract: A 1.5 Mt/a medium-pressure hydrocracking unit at a certain company experienced intermittent failures in copper strip corrosion tests during jet fuel production in its fractionation tower. By adapting the online washing technology used in non-hydrogenation units, issues in the hydrocracking unit’s fractionation tower can be successfully resolved. Based on the differentiated design of the fractionation system, nitrogen was introduced as a non-condensable gas into the fractionation tower, and the required amount of washing water was calculated using Aspen simulation software. Variations in process parameters such as temperature and liquid level during the online washing of the fractionation tower were analyzed and discussed, providing theoretical support for the application of online washing technology of fractionation towers in hydrocracking units.

Key words: hydrocracking, fractionation tower, online water washing, temperature