Processes herein may be used to thermally crack various hydrocarbon feeds, and may eliminate the refinery altogether while making the crude to chemicals process very flexible in terms of crude. In embodiments herein, crude is progressively separated into at least light and heavy fractions. Depending on the quality of the light and heavy fractions, these are routed to one of three upgrading operations, including a fixed bed hydroconversion unit, a fluidized catalytic conversion unit, or a residue hydrocracking unit that may utilize an ebullated bed reactor. Products from the upgrading operations may be used as feed to a steam cracker.

Processes herein may be used to thermally crack various hydrocarbon feeds, and may eliminate the refinery altogether while making the crude to chemicals process very flexible in terms of crude. In embodiments herein, crude is progressively separated into at least light and heavy fractions. Depending on the quality of the light and heavy fractions, these are routed to one of three upgrading operations, including a fixed bed hydroconversion unit, a fluidized catalytic conversion unit, or a residue hydrocracking unit that may utilize an ebullated bed reactor. Products from the upgrading operations may be used as feed to a steam cracker.

Processes herein may be used to thermally crack various hydrocarbon feeds, and may eliminate the refinery altogether while making the crude to chemicals process very flexible in terms of crude. In embodiments herein, crude is progressively separated into at least light and heavy fractions. Depending on the quality of the light and heavy fractions, these are routed to one of three upgrading operations, including a fixed bed hydroconversion unit, a fluidized catalytic conversion unit, or a residue hydrocracking unit that may utilize an ebullated bed reactor. Products from the upgrading operations may be used as feed to a steam cracker.

Processes herein may be used to thermally crack various hydrocarbon feeds, and may eliminate the refinery altogether while making the crude to chemicals process very flexible in terms of crude. In embodiments herein, crude is progressively separated into at least light and heavy fractions. Depending on the quality of the light and heavy fractions, these are routed to one of three upgrading operations, including a fixed bed hydroconversion unit, a fluidized catalytic conversion unit, or a residue hydrocracking unit that may utilize an ebullated bed reactor. Products from the upgrading operations may be used as feed to a steam cracker.

In the hydrocracking process in accordance with the invention, which comprises a hydrocracking section, a high pressure hot separator and a fractionation section, upstream of the fractionation section, a stripper or reboiler column type separation column is added which treats at least a portion of the heavy effluent obtained from the high pressure hot separator. All or a portion of the bottom fraction from said column, which is rich in polynuclear aromatic compounds, is purged. At least a portion of the bottom fraction obtained from the fractionation section, which is constituted by unconverted products, is recycled to the reaction section.

In the hydrocracking process in accordance with the invention, which comprises a hydrocracking section, a high pressure hot separator and a fractionation section, upstream of the fractionation section, a stripper or reboiler column type separation column is added which treats at least a portion of the heavy effluent obtained from the high pressure hot separator. All or a portion of the bottom fraction from said column, which is rich in polynuclear aromatic compounds, is purged. At least a portion of the bottom fraction obtained from the fractionation section, which is constituted by unconverted products, is recycled to the reaction section.

Processes herein may be used to thermally crack various hydrocarbon feeds, and may eliminate the refinery altogether while making the crude to chemicals process very flexible in terms of crude. In embodiments herein, crude is progressively separated into at least light and heavy fractions. Depending on the quality of the light and heavy fractions, these are routed to one of three upgrading operations, including a fixed bed hydroconversion unit, a fluidized catalytic conversion unit, or a residue hydrocracking unit that may utilize an ebullated bed reactor. Products from the upgrading operations may be used as feed to a steam cracker.

Processes herein may be used to thermally crack various hydrocarbon feeds, and may eliminate the refinery altogether while making the crude to chemicals process very flexible in terms of crude. In embodiments herein, crude is progressively separated into at least light and heavy fractions. Depending on the quality of the light and heavy fractions, these are routed to one of three upgrading operations, including a fixed bed hydroconversion unit, a fluidized catalytic conversion unit, or a residue hydrocracking unit that may utilize an ebullated bed reactor. Products from the upgrading operations may be used as feed to a steam cracker.

A process for recovering hydrogen from dehydrogenation reactor effluent is disclosed. A feed stream comprising hydrocarbons and hydrogen to a dehydrogenation reactor maintained at dehydrogenation conditions to provide a dehydrogenation reactor effluent. The dehydrogenation reactor effluent is passed to a cold box separation unit to provide a liquid hydrocarbon product stream and a recycle hydrogen stream. A return portion of the recycle hydrogen stream is passed to the reactor effluent compressor. The subject matter disclosed improved process and apparatus which enables the paraffin dehydrogenation reactor to run at reduced H.sub.2/HC ratio without requiring an investment in a resized compressor or resized turboexpanders or separators in the cold box.

A process for recovering hydrogen from dehydrogenation reactor effluent is disclosed. A feed stream comprising hydrocarbons and hydrogen to a dehydrogenation reactor maintained at dehydrogenation conditions to provide a dehydrogenation reactor effluent. The dehydrogenation reactor effluent is passed to a cold box separation unit to provide a liquid hydrocarbon product stream and a recycle hydrogen stream. A return portion of the recycle hydrogen stream is passed to the reactor effluent compressor. The subject matter disclosed improved process and apparatus which enables the paraffin dehydrogenation reactor to run at reduced H.sub.2/HC ratio without requiring an investment in a resized compressor or resized turboexpanders or separators in the cold box.