A process for producing C2 and C3 hydrocarbons by a) subjecting a mixed hydrocarbon stream comprising a middle distillate to first hydrocracking to produce a first hydrocracking product stream, b) subjecting a second hydrocracking feed stream to second hydrocracking to produce a second hydrocracking product stream, wherein the second hydrocracking is more severe than the first hydrocracking and c) subjecting a C4 hydrocracking feed stream to C4 hydrocracking optimized for converting C4 hydrocarbons into C3 hydrocarbons in the presence of a C4 hydrocracking catalyst to obtain a C4 hydrocracking product stream, wherein the C4 hydrocracking is more severe than the second hydrocracking. The first hydrocracking product stream, the second hydrocracking product stream and the C4 hydrocracking product stream are fed to a separation system.

Aromatics extraction and hydrocracking processes are integrated with a stream pyrolysis unit to optimize the performance of the hydrocracking units by processing the aromatic-rich and aromatic-lean fractions separately in order to better control the hydrocracking operating severity and/or catalyst reactor volume design requirements.

Aromatics extraction and hydrocracking processes are integrated with a stream pyrolysis unit to optimize the performance of the hydrocracking units by processing the aromatic-rich and aromatic-lean fractions separately in order to better control the hydrocracking operating severity and/or catalyst reactor volume design requirements.

Embodiments herein relate to a process flow scheme for the processing of gas oils and especially reactive gas oils produced by thermal cracking of residua using a split flow concept. The split flow concepts disclosed allow optimization of the hydrocracking reactor severities and thereby take advantage of the different reactivities of thermally cracked gas oils versus those of virgin gas oils. This results in a lower cost facility for producing base oils as well as diesel, kerosene and gasoline fuels while achieving high conversions and high catalyst lives.

Embodiments herein relate to a process flow scheme for the processing of gas oils and especially reactive gas oils produced by thermal cracking of residua using a split flow concept. The split flow concepts disclosed allow optimization of the hydrocracking reactor severities and thereby take advantage of the different reactivities of thermally cracked gas oils versus those of virgin gas oils. This results in a lower cost facility for producing base oils as well as diesel, kerosene and gasoline fuels while achieving high conversions and high catalyst lives.

Recycle of slurry hydrocracked product to a subsequent slurry hydrocracking reactor downstream of a lead slurry hydrocracking reactor produces reduced mesophase and provides better reactor stability as opposed to recycle to the lead slurry hydrocracking reactor. The recycle stream may be a vacuum bottoms stream and/or a slop wax stream from a fractionation column.

Recycle of slurry hydrocracked product to a subsequent slurry hydrocracking reactor downstream of a lead slurry hydrocracking reactor produces reduced mesophase and provides better reactor stability as opposed to recycle to the lead slurry hydrocracking reactor. The recycle stream may be a vacuum bottoms stream and/or a slop wax stream from a fractionation column.

Utilization of at least three strippers is proposed for a slurry hydrocracking unit to reduce heater duty for a product fractionation column. A stripping column for stripping a hydrocracked stream from a wash oil stripper is proposed in addition to a cold stripper for a cold hydrocracked stream and a warm stripper for a warm hydrocracked stream. The arrangement enables omission of heating a hot hydrocracked stream from a hot separator in a fired heater before product fractionation.

Utilization of at least three strippers is proposed for a slurry hydrocracking unit to reduce heater duty for a product fractionation column. A stripping column for stripping a hydrocracked stream from a wash oil stripper is proposed in addition to a cold stripper for a cold hydrocracked stream and a warm stripper for a warm hydrocracked stream. The arrangement enables omission of heating a hot hydrocracked stream from a hot separator in a fired heater before product fractionation.

The invention relates to a process for producing C2 and C3 hydrocarbons, comprising a) subjecting a mixed hydrocarbon stream to first hydrocracking in the presence of a first hydrocracking catalyst to produce a first hydrocracking product stream; and b) subjecting the first hydrocarbon product stream to C4 hydrocracking optimized for converting C4 hydrocarbons into C3 hydrocarbons in the presence of a C4 hydrocracking catalyst to obtain a C4 hydrocracking product stream comprising C2 and C3 hydrocarbons.