Process for conversion of petroleum feed comprising an ebullated bed hydroconversion step in a fixed bed hydrotreatment step for the production of low sulphur content fuel

Abstract

Process for conversion of petroleum feed for production of low sulphur content fuel comprising the following steps: a step of ebullated bed hydroconversion of the feed in the presence of a supported catalyst, a separation step allowing a residual fraction to be obtained, a step of fixed bed hydrotreatment of the residual fraction using an upstream system of permutable reactors.

1 . Method of conversion of a hydrocarbon-containing feed comprising at least one fraction of hydrocarbons with a sulphur content of at least 0.1% weight, an initial boiling temperature of at least 340° C. and a final boiling temperature of at least 440° C., comprising the following steps:
 a) a step of hydroconversion in the presence of hydrogen in at least one reactor containing a supported catalyst in an ebullated bed, 
 b) a step of separating the effluent obtained from step a) into at least one light fraction of hydrocarbon fuel bases and a heavy fraction containing predominantly compounds boiling at minimum 350° C., 
 c) a step of fixed bed hydrotreatment of at least part of the heavy fraction from step b) in which, under hydrotreatment conditions, the heavy fraction and hydrogen are passed over a hydrotreatment catalyst and in which the hydrotreatment step comprises one or a plurality of fixed bed hydrotreatment zones preceded by at least two storage zones also with fixed bed hydrotreatment, arranged in series to be used in a cyclic manner comprising the successive repetition of steps c″) and c′″) defined below:
 c′) a step in which the storage zones are used together for a duration at most equal to the deactivation and/or clogging time of one of them, 
 c″) a step during which the deactivated and/or clogged storage zone is short-circuited and the catalyst it contains is regenerated and/or replaced by fresh catalyst, and during which the other storage zone(s) is/are used, and 
 c′″) a step during which the storage zones are all used together, wherein the storage zone of which the catalyst has been regenerated during the preceding step is reconnected and said step is continued for a duration equal at most to the deactivation and/or clogging time of one of the storage zones. 
 
 
     
     
         2 . Method according to  claim 1  in which the hydrotreatment step comprises a first hydrodemetallation step comprising one or a plurality of fixed bed hydrodemetallation zones preceded by at least two of said hydrotreatment storage zones and a second subsequent hydrodesulphuration step comprising one or a plurality of fixed bed hydrodesulphuration zones in which, during the first hydrodemetallation step, under hydrodemetallation conditions, the feed of hydrocarbons and hydrogen is passed over a hydrodemetallation catalyst, then during the second subsequent step, under hydrodesulphuration conditions, the effluent from the first step is passed over a hydrodesulphuration catalyst. 
     
     
         3 . Method according to  claim 1 , in which during step a) the treatment in the presence of hydrogen is carried out under an absolute pressure of 2.5 to 35 MPa, at a temperature of 330 to 550° C. with an hourly spatial velocity of 0.1 to 10 h −1 , and the quantity of hydrogen mixed in the feed is from 50 to 5000 Nm 3 /m 3 . 
     
     
         4 . Method according to  claim 1 , in which the hydrotreatment step c) is performed under an absolute pressure of around 2 to 35 MPa, at a temperature of 300 to 500° C. with an hourly spatial velocity of 0.1 to 5 h −1 , and a quantity of hydrogen mixed in the feed is from 100 to 5000 Nm 3 /m 3 . 
     
     
         5 . Method according to  claim 1 , in which the hydrocarbon-containing feed is selected from the atmospheric residues, the vacuum residues from direct distillation, crude petroleum, topped crude petroleum, deasphalted oil, deasphalted resin, asphalts or deasphaltation pitch, residues from the conversion processes, aromatic extracts from the production chain of lubricant bases, bituminous sands or their derivatives, oil shales or their derivatives, taken alone or in combination. 
     
     
         6 . Method according to  claim 1 , in which the separation step b) is performed without decompression, the effluent from step a) is sent to the fractioning section with a cutting point between 200 and 400° C. so as to obtain a light fraction and said heavy fraction, said heavy fraction being sent to the hydrotreatment step while the light fraction is subjected to atmospheric distillation to give a gaseous fraction, at least one light fraction of hydrocarbons of the type naphtha, kerosene and/or diesel, and a vacuum distillate fraction, the latter being at least partly sent to the hydrotreatment step c). 
     
     
         7 . Method according to  claim 1 , in which the separation step b) is performed with decompression, the effluent from step a) is sent to a fractioning section with a cutting point between 200 and 400° C. to give a light fraction and said heavy fraction, and in which the heavy fraction is fractioned by atmospheric distillation into at least one atmospheric distillate fraction containing at least one light fraction of hydrocarbons of the type naphtha, kerosene and/or diesel, and an atmospheric residue fraction, said atmospheric residue fraction being at least partly fractioned by vacuum distillation into a vacuum distillate fraction containing vacuum gas oil and a vacuum residue fraction, at least part of said atmospheric residue fraction and/or vacuum residue fraction being sent to the hydrotreatment step c). 
     
     
         8 . Method according to  claim 1 , in which the heavy fraction obtained in step b) is subjected, before being sent to the hydrotreatment step, to separation of the sediment and catalyst fines using at least one rotating filter or also at least one basket filter or also a centrifuging system such as a hydrocyclone associated with filters or in-line decantation, or in which the heavy fraction obtained in step b) at the inlet to each storage zone passes through a filtering plate situated upstream from the catalytic bed(s) contained in the storage zone. 
     
     
         9 . Method according to  claim 1 , in which at least part of the effluent obtained in step c) is sent to a separation step, called step d), comprising an atmospheric distillation and a vacuum distillation and in which the effluent from the hydrotreatment step is fractioned by atmospheric distillation into a gaseous fraction, at least one atmospheric distillate fraction containing fuel bases (naphtha, kerosene and/or diesel) and an atmospheric residue fraction, at least part of the atmospheric residue is then fractioned by vacuum distillation into a vacuum distillate fraction containing vacuum gas oil and a vacuum residue fraction. 
     
     
         10 . Method according to  claim 9 , in which the light fraction obtained without decompression in the separation step b) is sent to the separation step d). 
     
     
         11 . Method according to  claim 9 , in which part of the vacuum residue fraction is recycled in the hydroconversion step a). 
     
     
         12 . Method according to  claim 9 , in which at least part of the vacuum distillate fraction and/or the vacuum residue fraction is/are sent to a catalytic cracking section, called step e), in which it is/they are treated under conditions allowing production of a gaseous fraction, a petrol fraction, a diesel fraction and a residual fraction. 
     
     
         13 . Method according to  claim 12 , in which at least part of the residual fraction obtained in catalytic cracking step e) is recycled to the inlet of step e) and/or a) and/or c). 
     
     
         14 . Method according to  claim 9 , in which the atmospheric residue and/or the vacuum distillate and/or the vacuum residue are mixed with flux bases selected from the light cycle oils from catalytic cracking, heavy cycle oils from catalytic cracking, the residue from catalytic cracking, kerosene, gas oil, vacuum distillate and/or a decanted oil. 
     
     
         15 . Method according to  claim 14 , in which the flux base is selected from kerosene, gas oil and/or vacuum distillate obtained from separation step b) of the process after hydroconversion, or gas oil and/or a fraction of the residual fraction obtained in the catalytic cracking step e).