The invention relates to a process for the recovery of aliphatic hydrocarbons from a liquid stream comprising aliphatic hydrocarbons, heteroatom containing organic compounds and optionally aromatic hydrocarbons, involving a) liquid-liquid extraction of said liquid stream with an extraction solvent thereby recovering part of the aliphatic hydrocarbons; b1) mixing the extract stream, comprising extraction solvent, aliphatic hydrocarbons, heteroatom containing organic compounds and optionally aromatic hydrocarbons, with a demixing solvent to recover additional aliphatic hydrocarbons; b2) mixing the remaining stream with additional demixing solvent to remove heteroatom containing organic compounds and optional aromatic hydrocarbons; and c) separation of the remaining stream into a demixing solvent stream and an extraction solvent stream. Further, the invention relates to a process for the recovery of aliphatic hydrocarbons from plastics comprising the above-mentioned process; and to a process for steam cracking a hydrocarbon feed

comprising aliphatic hydrocarbons as recovered in one of the above-mentioned processes.

Systems and methods are provided for partial upgrading of heavy hydrocarbon feeds to meet transport specifications, such as pipeline transport specifications. The systems and methods can allow for one or more types of improvement in heavy hydrocarbon processing prior to transport. In some aspects, the systems and methods can produce a partially upgraded heavy hydrocarbon product that satisfies one or more transport specifications while incorporating an increased amount of vacuum gas oil and a reduced amount of pitch into the partially upgraded heavy hydrocarbon product. In other aspects, the systems and methods can allow for increased incorporation of hydrocarbons into the fraction upgraded for transport, thereby reducing or minimizing the amount of hydrocarbons requiring an alternative method of disposal or transport. In still other aspects, the systems and methods can allow for reduced incorporation of external streams into the final product for transport while still satisfying one or more target properties.

Separation of asphaltenes from residual oil is carried out with naphtha as solvent. In particular, straight run naphtha obtained from the same crude oil source as the residual oil feed is used as the solvent. The mixture of deasphalted oil and solvent is passed to a hydroprocessing zone, without typical separation and recycle of the solvent back to the solvent deasphalting unit. Asphalt is separated from the residual oil (residue from atmospheric or vacuum distillation); the mixture of deasphalted oil and naphtha solvent is passed to the hydroprocessing unit.

An apparatus and process heat a process stream taken from a separator vessel by heat exchange with a hydroprocessed effluent stream and return the heated process stream to the separator vessel. We have found the significant heater duty reduction is provided particularly for a hydroprocessing unit. A spiral tube heat exchange can achieve heating of an already hot process stream by heat exchange with a hot effluent stream.

Methods are provided for processing deasphalted gas oils derived from thermally cracked resid fractions to form Group I, Group II, and/or Group III lubricant base oils. The yield of lubricant base oils (optionally also referred to as base stocks) can be increased by thermally cracking a resid fraction at an intermediate level of single pass severity relative to conventional methods. By performing thermal cracking to a partial level of conversion, compounds within a resid fraction that are beneficial for increasing both the viscosity and the viscosity index of a lubricant base oil can be retained, thus allowing for an improved yield of higher viscosity lubricant base oils from a thermally cracked resid fraction.

Separation of asphaltenes from residual oil is carried out with naphtha as solvent. In particular, straight run naphtha obtained from the same crude oil source as the residual oil feed is used as the solvent. The mixture of deasphalted oil and solvent is passed to a hydroprocessing zone, without typical separation and recycle of the solvent back to the solvent deasphalting unit. Asphalt is separated from the residual oil (residue from atmospheric or vacuum distillation); the mixture of deasphalted oil and naphtha solvent is passed to the hydroprocessing unit.

Separation of asphaltenes from residual oil is carried out with naphtha as solvent. In particular, straight run naphtha obtained from the same crude oil source as the residual oil feed is used as the solvent. The mixture of deasphalted oil and solvent is passed to a hydroprocessing zone, without typical separation and recycle of the solvent back to the solvent deasphalting unit. Asphalt is separated from the residual oil (residue from atmospheric or vacuum distillation); the mixture of deasphalted oil and naphtha solvent is passed to the hydroprocessing unit.

Methods and systems of producing chemical feedstocks from crude oil can include: introducing a fraction of crude oil into a catalytic hydrovisbreaker reactor, wherein the crude oil fraction is dealkylated after introduction; introducing a product stream from the catalytic hydrovisbreaker reactor and a solvent into a solvent de-asphalter unit; and introducing de-asphalted oil from the unit into a two-stage hydrocracker to produce the chemical feedstocks. The crude oil fraction can be atmospheric residue or vacuum residue. The chemical feedstocks can include C.sub.3.sup.− gases, C.sub.4-C.sub.5 gases, naphtha, BTX, and gas oil. The chemical feedstocks can be used to produce olefins and polymers.

The invention concerns a method for converting heavy hydrocarbon feedstocks of which at least 50% by weight boils at a temperature of at least 300° C., and in particular vacuum residues. The feedstocks are subjected to a first step a) of deep hydroconversion, optionally followed by a step b) of separating a light fraction, and a heavy residual fraction is obtained from step b) of which at least 80% by weight has a boiling temperature of at least 250° C. Said fraction from step b) or the effluent from step a) is then subjected to a second step c) of deep hydroconversion. The overall hourly space velocity for steps a) to c) is less than 0.1 h.sup.−1. The effluent from step c) is fractionated to separate a light fraction. The heavy fraction obtained, of which 80% by weight boils at a temperature of at least 300° C., is sent to a deasphalting step e). The deasphalted fraction DAO is then preferably converted in a step f) chosen from ebullated bed hydroconversion, fluidised bed catalytic cracking and fixed bed hydrocracking.

A device for the descending flow of a hydrocarbon-containing liquid containing solid particles at the bottom of an item of equipment (1) and a process for the conversion of hydrocarbon-containing feedstocks implementing said device.