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 and system for treating a hydroprocessing unit effluent gas stream for recycling includes introducing the effluent gas stream into a hydrogen purification zone and recovering a hydrogen-rich gas stream and a liquid stream containing a mixture that includes C1 to C4 hydrocarbons and H.sub.2S which is then mixed with an oxidant and fed to an oxidation unit containing catalyst for conversion of the H.sub.2S to elemental sulfur vapors that is separated for recovery of the elemental sulfur, and recovering a sweetened mixture that includes C1 to C4 hydrocarbons. Alternatively, the hydroprocessing unit effluent gas stream containing H.sub.2S is cooled, contacted with a solvent to absorb the C1 to C4 hydrocarbons and H.sub.2S, with the hydrogen-rich stream being recovered for recycling to the hydroprocessing unit, and the rich liquid solvent being flashed to produce a lean solvent stream for recycling to the adsorption zone and a mixed gas stream that includes the C1 to C4 hydrocarbons and H.sub.2S that is passed to an oxidation zone and is reacted with an oxidant in the presence of a catalyst to complete the process as described above for the recovery of elemental sulfur and a mixture that includes the sweetened C1 to C4 hydrocarbons.

The invention relates to a utility fluid, such as a fluid containing aromatic and non-aromatic ringed molecules, useful as a diluent when hydroprocessing pyrolysis tar, such as steam cracker tar. The specified utility fluid comprises ≧10.0 wt % aromatic and non-aromatic ring compounds and each of the following: (a) ≧1.0 wt % of 1.0 ring class compounds; (b) ≧5.0 wt % of 1.5 ring class compounds; (c) ≧5.0 wt % of 2.0 ring class compounds; and (d) ≦0.1 wt % of 5.0 ring class compounds. The invention also relates to methods for producing such a utility fluid and to processes for hydroprocessing pyrolysis tar.

The invention relates to a utility fluid, such as a fluid containing aromatic and non-aromatic ringed molecules, useful as a diluent when hydroprocessing pyrolysis tar, such as steam cracker tar. The specified utility fluid comprises ≧10.0 wt % aromatic and non-aromatic ring compounds and each of the following: (a) ≧1.0 wt % of 1.0 ring class compounds; (b) ≧5.0 wt % of 1.5 ring class compounds; (c) ≧5.0 wt % of 2.0 ring class compounds; and (d) ≦0.1 wt % of 5.0 ring class compounds. The invention also relates to methods for producing such a utility fluid and to processes for hydroprocessing pyrolysis tar.

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.

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.