Process and installation for conversion of heavy petroleum fractions in a fixed bed with integrated production of middle distillates with a very low sulfur content

Abstract

This invention relates to a process and an installation for treatment of a heavy petroleum feedstock, of which at least 80% by weight has a boiling point of greater than 340° C., whereby the process comprises the following stages:(a) Hydroconversion in a fixed-bed reactor operating with an upward flow of liquid and gas, whereby the net conversion in products boiling below 360° C. is from 10 to 99% by weight;(b) Separation of the effluent obtained from stage (a) into a gas containing hydrogen and H2S, a fraction comprising the gas oil, and optionally a fraction that is heavier than the gas oil and a naphtha fraction;c) Hydrotreatment by contact with at least one catalyst of at least the fraction comprising the gas oil obtained in stage (b);d) Separation of the effluent obtained at the end of stage (c) into a gas containing hydrogen and at least one gas oil fraction having a sulfur content of less than 50 ppm, preferably less than 20 ppm, and more preferably still less than 10 ppm,the hydroconversion stage (a) being conducted at a pressure P1 and the hydrotreatment stage (c) being conducted at a pressure P2, the difference ΔP=P1−P2 being at least 2 MPa, the hydrogen supply for the hydroconversion (a) and hydrotreatment (c) stages being ensured by a single compression system with n stages.

Description

FIELD OF THE INVENTION[0001]The invention relates to an improved process for conversion of heavy petroleum fractions in a fixed bed with integrated production of gas oil fractions with very low sulfur content, and the installation allowing the implementation of said process.[0002]This invention relates to a process and an installation for the treatment of heavy hydrocarbon feedstocks containing sulfur-containing, nitrogen-containing and metallic impurities. It relates to a process making it possible to convert at least partially such a hydrocarbon feedstock, for example a direct-distillation vacuum distillate, a vacuum distillate that is obtained from a conversion process or oils that are deasphalted with solvent, into gas oils that meet sulfur specifications, i.e., having less than 50 ppm of sulfur, preferably less than 20 ppm, and even more preferably less than 10 ppm, and one or more heavy products that advantageously can be used as a feedstock for catalytic cracking (such as flu...

AI Technical Summary

Benefits of technology

[0012]The present inventors have found that it is possible to minimize investment costs by optimizing operating pressures used while obtaining gas oils of good quality having such limited sulfur contents.DETAILED DESCRIPTION OF THE INVENTION

[0021]Thus, in the process according to the invention, pressures that are completely different for each of the hydroconversion and hydrotreatment stages can be used, which makes it possible in particular to significantly limit the investment costs.

Problems solved by technology

The gasolines and the gas oils that are obtained from the conversion process, such as, for example, hydroconversion, are very refractory in hydrotreatment compared to gas oils that are obtained directly from the atmospheric distillation of crude oils.

This process, however, makes it possible to reduce sulfur levels below 50 ppm only under very rigorous pressure conditions, which considerably increases the cost of the gas oil that is ultimately obtained.

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