Technical development and industrial application of producing industrial white oil by hydrocracking unit

Objective To reduce the ratio of diesel to gasoline in refinery and improve the economic benefit of enterprise.

Methods The feasibility of producing 5^# industrial white oil in 4.0×10⁶ t/a wax oil hydrocracking unit of Huizhou Petrochemical Company was analyzed. It is considered feasible to produce 5^# industrial white oil by raising the initial boiling point of diesel fraction. In the early stage, the plant tried to raise the initial boiling point of diesel by reducing the pressure of the main fractionator, adding a steam stripper and changing the reboiler of the original diesel stripper to the steam stripping process, but hadn't achieved good operation effect. In view of the limitations of above three processes, the hot nitrogen stripping process was developed in this project. The process used hot nitrogen stripping to replace the reboiler at the bottom of the diesel stripper, and the non-condensable gas was discharged from the top of the main fractionator to maintain tower pressure stably.

Results After the implementation of the nitrogen stripping process, the output of white oil products was 60 t/h, kerosene output increased by 14 t/h, non-condensable gas output increased by 1.3 t/h, and diesel product was no longer produced. The open flash point of white oil products increased from 85 ℃ to 126 ℃, which solved the problems of low open flash point and water contained in product.

Conclusions The 5^# industrial white oil products produced by this process is stable in property and meet the requirements of the industry indicators. Meanwhile, the reform work is small and the economic benefit is remarkable, which has important reference significance for the production optimization of similar plants at home and abroad.