Patent ID: 6379535
Filing Date: 2002-04-30
Classification: C10G

Abstract:
A process for hydrocracking a hydrocarbonaceous feedstock which process comprises:(a) passing a hydrocarbonaceous feedstock, a liquid recycle stream and hydrogen to a denitrification and desulfurization reaction zone containing a catalyst and recovering a denitrification and desulfurization reaction zone effluent therefrom; (b) passing said denitrification and desulfurization reaction zone effluent to a hydrocracking zone containing hydrocracking catalyst; (c) partially condensing the reaction zone effluent from step (b) to produce a hydrogen-rich gaseous stream and a first liquid hydrocarbonaceous stream; (d) passing said first liquid hydrocarbonaceous stream to a flashing zone having a reduced pressure to produce a first gaseous stream comprising hydrogen and normally gaseous hydrocarbons and a second liquid hydrocarbonaceous stream; (e) stripping said second liquid hydrocarbonaceous stream to produce a second gaseous stream comprising normally gaseous hydrocarbons and a third liquid hydrocarbonaceous stream comprising hydrocarbons boiling at a temperature below the boiling range of said hydrocarbonaceous feedstock, hydrocarbons boiling at a temperature in the boiling range of said hydrocarbonaceous feedstock and heavy polynuclear aromatic compounds; (f) fractionating said third liquid hydrocarbonaceous stream in a first zone of a divided-wall fractionation zone to produce at least one liquid hydrocarbonaceous product stream and a fourth liquid hydrocarbonaceous stream comprising hydrocarbons boiling at a temperature in the boiling range of said hydrocarbonaceous feedstock and heavy polynuclear aromatic compounds; (g) reintroducing at least a portion of said fourth liquid hydrocarbonaceous stream into a second zone located in the bottom end of said divided-wall fractionation zone to produce a fifth hydrocarbonaceous stream rich in polynuclear aromatic compounds; (h) recycling at least another portion of said fourth liquid hydrocarbonaceous stream to said denitrification and desulfurization reaction zone to provide at least a portion of said liquid recycle stream; and (i) recovering said liquid hydrocarbonaceous product stream.