Abstract: The 0.8Mt/a solvent deasphalting unit of a refining and chemical company was shut down in October 2024, due to the change in the overall processing mode of the entire plant. Since then, the unit has been in a five-month shutdown with material remaining inside for static storage. Due to incomplete material withdrawal and thorough purging of the system, problems such as prolonged solvent purification time during shutdown and inability to conduct nitrogen gas tightness tests in stages during startup, resulting in numerous near-critical leakage points, and poor flow in the secondary solvent branch process occurred. Through regular and scheduled inspections, assistance from LDAR detection equipment, and staged steam purging, the smooth shutdown and startup of the solvent deasphalting unit were effectively ensured.

Key words: solvent deasphalting unit, shutdown, startup, butane solvent circulation purification