Abstract: Determining the emergency pressure relief orifice diameter is crucial for the safe operation of hydrogenation unit. The method to calculate the gas phase volume of main equipment in recycle hydrogen system and the method to verify the emergency pressure relief orifice diameter are introduced, and the actual operation result fall within the engineering tolerances. It provides guidance for the determination of orifice diameter for new and revamped hydrogenation units.

Key words: emergency pressure relief test , orifice diameter , gas phase volume of recycle hydrogen system , natural logarithmic equation slope