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.

The present invention concerns a process for the treatment of a hydrocarbon feed containing hydrogen and hydrocarbons including C.sub.1 to C.sub.4 hydrocarbons, employing a first and a second recontacting step and in which the gaseous effluent obtained from the second recontacting step is recycled to the first recontacting step. The process is of particular application to the treatment of a hydrocarbon feed obtained from catalytic reforming with a view to recovering hydrogen and C.sub.3 and C.sub.4 hydrocarbons.

A process for recovery of olefins includes flashing at least a portion of an alkane feed stream to produce a flashed alkane feed stream, introducing the flashed alkane feed stream in a cold box, a fractionation system, or both as cooling medium, compressing and cooling a gaseous feed stream, separating a compressed and cooled feed stream into first residual vapor stream and first liquid residue stream, cooling the first residual vapor stream, separating a cooled first residual vapor stream into a second vapor residue stream and a second liquid residue stream, separating the first liquid residue stream into an overhead stream of the light removal column and a bottom stream of the light removal column, and fractionating at least a portion of the second liquid residue stream and the bottom stream of the light removal column to produce overhead vapor stream, liquid recycle stream, and bottom liquid stream.

Pyrolytic emissions often include molecularly decomposed hydrocarbons, as well as byproducts from pyrolytic processes. Unfortunately, legacy processing treats effluent streams, including pyrolytic emissions, as waste that is released into the air-even though such pyrolytic emissions streams often include greenhouse gases and pollutants such as carbon dioxide, nitrogen oxides, sulfur dioxide, volatile organic compounds, and particulate matter-the discharge of which contributes to global greenhouse gas emissions. Disclosed herein are pyrolytic emissions looping systems that include several reactors where each of the several reactors converts different hydrocarbons into different useful end-products, thus providing a way to continuously recycle the effluent gas stream from pyrolytic processes.