Deep hydroconversion process using an extraction of aromatics and resins, with upgrading of the hydroconversion extract and raffinate in downstream units

Abstract

Process for deep conversion of heavy hydrocarbon feed, which includes:a) ebullated bed hydroconverting the feed in at least one three-phase reactor containing at least one supported hydroconversion catalyst;b) atmospheric fractionating effluent from a) producing gasoline fraction, gas oil cut, and atmospheric residue;c) vacuum fractionation of at least a portion of the atmospheric residue to obtain a vacuum gas oil fraction and an unconverted vacuum residue fraction;d) deasphalting at least a portion of the unconverted vacuum residue fraction with an organic solvent obtaining a hydrocarbon cut depleted in asphaltenes, termed deasphalted oil, and residual asphalt; ande) liquid / liquid extraction on the hydrocarbon cut depleted in asphaltenes extracting aromatics by a polar solvent producing an extract enriched in aromatics and resins and a raffinate depleted in aromatics and resins, at least a portion of the extract sent to the inlet of the hydroconversion as an aromatic diluent.

Description

FIELD OF THE INVENTION[0001]The invention relates to the field of the deep conversion of heavy hydrocarbon feeds in order to obtain upgradable hydrocarbon cuts such as liquefied petroleum gas (or LPG), gasolines or naphthas, kerosene, gas oil and oils.[0002]The invention pertains to process flow diagrams which can be used to improve the performances of conversion units by introducing an extraction of the aromatics.[0003]As a general rule, refineries comprise a unit for deep hydroconversion of residue followed by an atmospheric fractionation then a vacuum fractionation and downstream, a catalytic cracking unit and / or a hydrocracking unit. Optionally, a unit for deasphalting residue not converted during the hydroconversion is also present.[0004]Deep hydroconversion processes are used in the refinery to transform mixtures of heavy hydrocarbons into easily upgradable products. They are usually principally used to con vert heavy feeds such as oil cuts or heavy synthetics, for example res...

AI Technical Summary

Benefits of technology

The invention has a step called deasphalting that removes impurities from the asphalt before extracting the aromatics. This results in a higher purity of the aromatic extract.

Problems solved by technology

The asphaltenes are unstable and have a tendency to precipitate in hot spots such as the furnaces and column bottoms (more particularly in the vacuum column).

As a consequence, the units and columns are periodically stopped for cleaning, which reduces their availability time.

In a typical refinery, the possible diluents such as the heavy residual fraction (slurry) from catalytic cracking, are available in limited quantities and are thus a factor limiting the maximum conversion which can be obtained in deep hydroconversion units.

Since the atmospheric residue obtained from the hydroconversion is not deasphalted in the process described in that patent, the extract obtained from the extraction unit is likely to contain asphaltenes, which could lead to a degradation of the hydroconversion performances in the case of recycling it to the hydroconversion.

However, none of the prior art documents can overcome all of the problems mentioned.

Images