Process for converting petroleum feedstocks comprising a visbreaking stage, a maturation stage and a stage of separating the sediments for the production of fuel oils with a low sediment content

Abstract

The invention relates to a process for converting a hydrocarbon-containing feedstock containing at least one hydrocarbon fraction having a sulphur content of at least 0.1% by weight, an initial boiling temperature of at least 340° C. and a final boiling temperature of at least 440° C., making it possible to obtain a heavy fraction having a sediment content after ageing of less than or equal to 0.1% by weight, said process comprising the following stages: a) a stage of visbreaking the feedstock in at least one maturation chamber (soaker), b) a stage of separating the effluent obtained at the end of stage a), c) a stage of maturation of the heavy fraction originating from stage b), d) a stage of separating the sediments from the heavy fraction originating from the maturation stage c) in order to obtain said heavy fraction.

1 ) Process for converting a hydrocarbon-containing feedstock containing at least one hydrocarbon fraction having a sulphur content of at least 0.1% by weight, an initial boiling temperature of at least 340° C. and a final boiling temperature of at least 440° C., making it possible to obtain a heavy fraction having a sediment content after ageing of less than or equal to 0.1% by weight, said process comprising the following stages:
 a) a stage of visbreaking the feedstock in at least one maturation chamber (soaker), 
 b) a stage of separating the effluent obtained at the end of stage a) into at least one light hydrocarbon fraction containing fuel bases and a heavy fraction containing compounds boiling at at least 350° C., 
 c) a stage of maturation of the heavy fraction originating from the separation stage b) making it possible to convert a part of the potential sediments to existing sediments, carried out for a duration comprised between 1 and 1500 minutes, at a temperature comprised between 50 and 350° C., and at a pressure of less than 20 MPa, 
 d) a stage of separating the sediments from the heavy fraction originating from the maturation stage c) in order to obtain said heavy fraction. 
 
     
     
         2 ) Process according to  claim 1  in which the visbreaking stage is carried out at a temperature comprised between 370° C. and 500° C., for a duration comprised between 1 and 60 minutes, a total pressure of less than 10 MPa. 
     
     
         3 ) Process according to  claim 1  in which a stage of hydrotreating the feedstock is carried out upstream of the visbreaking stage a). 
     
     
         4 ) Process according to  claim 1  in which the visbreaking stage is carried out in the presence of hydrogen. 
     
     
         5 ) Process according to one of the preceding claims in which, during stage b), the effluent obtained at the end of stage a) is separated in a high-pressure high-temperature HPHT separator into a light fraction and a heavy fraction containing mainly compounds boiling at at least 350° C. 
     
     
         6 ) Process according to  claim 1  in which at least a part of the fraction known as heavy originating from stage b) is fractionated by atmospheric distillation into at least one atmospheric distillate fraction containing at least one light hydrocarbon fraction of the naphtha, kerosene and/or diesel type and an atmospheric residue fraction. 
     
     
         7 ) Process according to  claim 1  in which the stage of maturation of the heavy fraction originating from stage b) is carried out in the presence of an inert gas and/or an oxidizing gas. 
     
     
         8 ) Process according to  claim 1  in which the separation stage d) is carried out by means of at least one separation means selected from a filter, a separation membrane, a filtering bed of solids of the organic or inorganic type, an electrostatic precipitation, a centrifugation system, decantation, drawing- off by means of an endless screw. 
     
     
         9 ) Process according to  claim 1  also comprising a fixed-bed hydrotreatment stage f) implemented on at least a part of the heavy fraction originating from stage d) in which the heavy fraction and hydrogen are passed over a hydrotreatment catalyst under hydrotreatment conditions. 
     
     
         10 ) Process according to  claim 9  in which the hydrotreatment stage is carried out at a temperature comprised between 300 and 500° C., an absolute pressure comprised between 5 MPa and 25 MPa, an overall hourly space velocity (LHSV) situated in a range from 0.1 h −1  to 5 h −1 , a quantity of hydrogen mixed with the feedstock of 100 to 5000 Nm 3 /m 3 . 
     
     
         11 ) Process according to  claim 9  in which a co-feedstock is introduced with the heavy fraction in the hydrotreatment stage f). 
     
     
         12 ) Process according to  claim 11  in which the co-feedstock is selected from atmospheric residues, vacuum residues originating from direct distillation, deasphalted oils, aromatic extracts originating from lubricant base production chains, hydrocarbon-containing fractions or a mixture of hydrocarbon-containing fractions able to be selected from the products originating from a fluid catalytic cracking process: a light cycle oil (LCO), a heavy cycle oil (HCO), a decanted oil, or able to originate from distillation, gas oil fractions, in particular those obtained by atmospheric or vacuum distillation, such as for example vacuum gas oil. 
     
     
         13 ) Process according to  claim 1  in which the feedstock treated is selected from atmospheric residues, vacuum residues originating from direct distillation, crude oils, topped crude oils, deasphalted oils, deasphalting resins, asphalts or deasphalting pitches, residues originating from conversion processes, aromatic extracts originating from lubricant base production chains, bituminous sands or derivatives thereof, oil shales or derivatives thereof, alone or in a mixture. 
     
     
         14 ) Process according to  claim 1  in which the heavy fractions originating from stages d) and/or f) are mixed with one or more fluxing bases selected from the group constituted by the light cycle oils of a catalytic cracking, the heavy cycle oils of a catalytic cracking, the residue of a catalytic cracking, a kerosene, a gas oil, a vacuum distillate and/or a decanted oil.