Process For The Intense Conversion Of Residues, Maximizing The Gasoline Yield (Axens)

Process For The Intense Conversion Of Residues, Maximizing The Gasoline Yield (Axens)
United States Patent Application 20160177203
Morel; Frederic ;   et al.   June 23, 2016
Assignee: AXENS Rueil Malmaison Cedex
Abstract
A process for the intense conversion of a heavy hydrocarbon feed, comprising a) ebullated bed hydroconversion of the feed; b) separating at least a portion of hydroconverted liquid effluent obtained from a); c)i) either hydrotreatment of at least a portion of the gas oil fraction and of the vacuum gas oil fraction obtained from b), ii) or hydrocracking at least a portion of gas oil fraction and vacuum gas oil fraction obtained from b); d) fractionation of at least a portion of the effluent obtained from c)i) or c)ii); e) recycling at least a portion of unconverted vacuum gas oil fraction obtained from the fractionation d) to said first hydroconversion a); f) hydrocracking at least a portion of gas oil fraction obtained from fractionation d); g) recycling all or a portion of effluent obtained from f) to the fractionation d).
Description
[0001] The invention relates to the field of the production of gasoline (also frequently known as naphtha) from oil residues.
[0002] The concatenation of conversion and hydrocracking units in the treatment of oil residue feeds is known in the prior art.
[0003] U.S. Pat. No. 5,980,730 and U.S. Pat. No. 6,017,441 describe a process for the intense conversion of a heavy oil fraction, said process comprising a step for hydroconversion in a three-phase ebullated bed, an atmospheric distillation of the effluent obtained, a vacuum distillation of the atmospheric residue obtained after this distillation, a deasphalting step for the vacuum residue obtained and a hydrotreatment of the deasphalted fraction mixed with the distillate obtained during the vacuum distillation. It is also possible in that process to send at least a fraction of the hydrotreated effluent to a catalytic cracking section or to recycle a fraction of the effluent obtained from deasphalting or, in another variation a fraction of the asphalt, to the first hydroconversion step or indeed to send a heavy liquid fraction obtained from the hydrotreatment step to a fluidized bed catalytic cracking section.
[0004] U.S. Pat. No. 6,620,311 describes a conversion process which can be used to increase the yield of middle distillates. That process comprises a step for three-phase ebullated bed conversion, sending the effluent obtained to a separation section in order to produce an overhead distillate comprising a gas, gasoline and gas oil and from the bottom, essentially hydrocarbons with a boiling point which is higher than an atmospheric gas oil. The distillate is then treated in a hydrodesulphurization unit and the bottom fraction is treated in a catalytic cracking section in the absence of hydrogen, for example of the fluidized bed cracking type. That type of cracking thus differs from a hydrocracking step operated in fixed bed mode and in the presence of hydrogen.
[0005] U.S. Pat. No. 7,919,054 describes a facility for the treatment of heavy oil feeds, comprising an ebullated bed hydroconversion section, a separation and a section for fixed bed hydrotreatment of the distillate obtained in the presence of hydrogen. That hydrotreatment may be a mild hydrocracking (4.5 to 16 MPa) or more severe hydrocracking (7 to 20 MPa).
[0006] However, the processes proposed in the prior art suffer from a limitation in the gas oil production yield. In fact, those processes produce a relatively large purge quantity of vacuum distillates from the bottom of the column of the units for vacuum separation of the hydroconversion effluents. Those fractions are obtained from vacuum separations and so, because of their polycondensed structures, they are difficult to upgrade into an oil base compared with vacuum distillate fractions obtained from straight run distillation of oil cuts.
[0007] The Applicant proposes a novel process with a particular arrangement of the conversion units and optional deasphalting of the solvent in order to obtain higher production yields of gasoline (also known as naphtha) than in the prior art processes.
[0008] One aim of the invention is to obtain an intense conversion of the feed of oil residues while maximizing the gasoline production.
AIM OF THE INVENTION
[0009] The present invention concerns a process for the intense conversion of a heavy hydrocarbon feed, comprising the following steps:
[0010] a) a first step for ebullated bed hydroconversion of the feed in the presence of hydrogen, comprising at least one three-phase reactor containing at least one ebullated bed hydroconversion catalyst;
[0011] b) a step for separating at least a portion of the hydroconverted liquid effluent obtained from step a) into a gasoline fraction, a gas oil fraction, a vacuum gas oil fraction and an unconverted residual fraction;
[0012] c) i) either a step for hydrotreatment of at least a portion of the gas oil fraction and the vacuum gas oil fraction obtained from step b) in a reactor comprising at least one fixed bed hydrotreatment catalyst; [0013] ii) or a first step for hydrocracking at least a portion of the gas oil fraction and the vacuum gas oil fraction obtained from step b) in a reactor comprising at least one fixed bed hydrocracking catalyst;
[0014] d) a step for fractionating at least a portion of the effluent obtained from step c)i) or step c)ii) into a gasoline fraction, a gas oil fraction and an unconverted vacuum gas oil fraction;
[0015] e) a step for recycling at least a portion of the unconverted vacuum gas oil fraction obtained from fractionation step d) to said first hydroconversion step a);
[0016] f) a second step for hydrocracking at least a portion of the gas oil fraction obtained from fractionation step d);
[0017] g) a step for recycling all or a portion of the effluent obtained from step f) to the fractionation step d).
[0018] The feed for the present invention is advantageously selected from heavy hydrocarbon feeds of the vacuum or atmospheric residue type obtained, for example, by straight run distillation of an oil cut or by vacuum distillation of crude oil, distillate type feeds such as vacuum gas oil or deasphalted oils, asphalts obtained from solvent deasphalting of oil residues, coal in suspension in a hydrocarbon fraction such as, for example, gas oil obtained by vacuum distillation of crude oil (also known as vacuum distilled gas oil), or a distillate obtained from coal liquefaction, used alone or as a mixture. The feed of the invention may contain vacuum residues such as Arabian Heavy vacuum residues, Ural vacuum residues and the like, vacuum residues obtained from Canadian or Venezuelan type heavy crudes, or a mixture of atmospheric residues or vacuum residues of diverse origins.
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