Method for converting hydrocarbon feedstock comprising a shale oil by hydroconversion in an ebullating bed, fractionation by atmospheric distillation and hydrocracking

Abstract

Method and plant for converting hydrocarbon feedstock comprising a shale oil, comprising a step of hydroconverting in an ebullating bed, a fractionation into a light fraction, a naphtha fraction, a gas-oil fraction and a fraction heavier than gas-oil, the naphtha and gas oil fraction being hydrotreated, the fraction heavier than gas oil being hydrocracked, the products of the hydrocracking being sent to the step for hydrotreating. The method aims to maximize the yield of fuel bases.

1 . Method for converting a shale oil or a mixture of shale oils having a nitrogen content of at least 0.1%, comprising:
 a) the feedstock is conveyed into a section for hydroconverting in the presence of hydrogen, said section comprising at least one ebullating bed reactor operating in gas and liquid upflow mode and containing at least one supported hydroconversion catalyst,   b) the effluent obtained in step a) is conveyed at least partly into a fractionating zone, from which, by atmospheric distillation, a gaseous fraction, a naphtha fraction, a gas-oil fraction and a fraction heavier than gas-oil are recovered,   c) said naphtha fraction is treated at least partly in a first section for hydrotreating in the presence of hydrogen, said section comprising at least one fixed bed reactor containing at least one hydrotreating catalyst,   d) said gas-oil fraction is treated at least partly in a second section for hydrotreating in the presence of hydrogen, said section comprising at least one fixed bed reactor containing at least one hydrotreating catalyst, and   e) the fraction heavier than the gas-oil fraction is treated at least partly in a hydrocracking section in the presence of hydrogen.   
     
     
         2 . Method according to  claim 1 , wherein the hydrocracking effluents obtained at the end of step e) are fractionated into a second gaseous fraction, a second naphtha fraction, a second gas-oil fraction, and a second fraction which is heavier than gas-oil. 
     
     
         3 . Method according to  claim 2 , wherein the second naphtha fraction is treated, at least partly, in the hydrotreating section of step c). 
     
     
         4 . Method according to  claim 2 , wherein the second gas oil fraction is treated, at least partly, in the hydrotreating section of step d). 
     
     
         5 . Method according to  claim 2 , wherein the second fraction heavier than gas oil is treated, at least partly, in the hydroconverting section of step a). 
     
     
         6 . Method according to  claim 1 , wherein the hydrocracking effluents obtained at the end of step e) are separated into a gas oil fraction and a fraction which is lighter than gas oil and a fraction which is heavier than gas-oil. 
     
     
         7 . Method according to  claim 6 , wherein the second fraction heavier than gas oil is treated, at least partly, in the hydroconverting section of step a). 
     
     
         8 . Method according to  claim 6 , wherein the gas oil fraction and the fraction which is lighter than gas oil is conveyed, at least partly, in a fractionating zone of step b). 
     
     
         9 . Method according to  claim 2 , wherein the second fraction heavier than gas oil is treated, at least partly, in the hydrocracking section of step e). 
     
     
         10 . Method according to  claim 1 , wherein the effluent obtained in step a) is fractionated by atmospheric distillation into a gaseous fraction having a boiling point of less than 50° C., a naphtha fraction boiling at between about 50° C. and 150° C., a gas-oil fraction boiling at between about 150° C. and 370° C., and a fraction which is heavier than the gas-oil fraction and which boils at above 340° C. 
     
     
         11 . Method according to  claim 1 , wherein the fixed bed hydrotreating sections in steps c) and/or d) comprise, upstream of the catalytic hydrotreating beds, at least one specific guard bed for arsenic compounds and silicon compounds. 
     
     
         12 . Method according to  claim 1 , wherein hydroconverting step a) operates at a temperature of between 300° C. and 550° C., at a total pressure of between 2 and 35 MPa, at a mass hourly velocity ((t of feedstock/h)/t of catalyst) of between 0.2 and 1.5 h −1  and at a hydrogen/feedstock ratio of between 50 and 5000 Nm 3 /m 3 . 
     
     
         13 . Method according to  claim 1 , wherein step c) of hydrotreating the naphtha fraction operates at a temperature of between 280° C. and 380° C., at a total pressure of between 4 and 15 MPa, at a mass hourly velocity ((t of feedstock/h)/t of catalyst) of between 0.1 h −1  and 5 h −1 , and at a hydrogen/feedstock ratio of between 100 and 5000 Nm 3 /m 3 . 
     
     
         14 . Method according to  claim 1 , wherein step d) of hydrotreating the gas-oil fraction operates at a temperature of between 320° C. and 450° C., at a total pressure of between 7 and 20 MPa, at a mass hourly velocity ((t of feedstock/h)/t of catalyst) of between 0.1 and 1 h −1 , and at a hydrogen/feedstock ratio of between 100 and 5000 Nm 3 /m 3 . 
     
     
         15 . Method according to  claim 1 , wherein step e) of hydrocracking the fraction heavier than gas-oil operates at a temperature of between 350° C. and 450° C., at a total pressure of between 10 and 20 MPa, at a mass hourly velocity ((t of feedstock/h)/t of catalyst) of between 0.3 and 7 h −1 , and at a hydrogen/feedstock ratio of between 100 and 5000 Nm 3 /m 3 . 
     
     
         16 . Method according to  claim 1 , wherein the catalysts in hydroconverting step a), hydrotreating steps c) and d), hydrocracking step e) are independently selected from the group of catalysts comprising a group VIII metal selected from the group consisting of Ni and/or Co, optionally a group VIB metal selected from the group consisting of Mo and/or W, on an amorphous support selected from the group consisting of alumina, silica, silica-aluminas, magnesia, clays and their mixtures, or on a support comprising at least partly a zeolite material. 
     
     
         17 . Method according to  claim 1 , wherein the shale oil or the mixture of shale oils is supplemented with a hydrocarbon feedstock selected from the group consisting of oils derived from coal, oils obtained from heavy tars and bituminous sands, vacuum distillates, and residues of direct distillation, vacuum distillates and unconverted residues obtained from a residue conversion process, oils deasphalted with solvents, light cycle oils, heavy cycle oils, gas-oil cuts originating from catalytic cracking and having generally a distillation range from approximately 150° C. to approximately 650° C., aromatic extracts obtained in the manufacture of lubricating oils, pyrolysis oils of ligneous residues such as wood residues, crudes obtained from biomass (“biocrudes”), vegetable oils and animal fats or mixtures of such feedstocks. 
     
     
         18 . Synthetic crude obtained by a method according to  claim 1 . 
     
     
         19 . Plant for treating a shale oil, comprising:
 a section for hydroconverting in the presence of hydrogen, comprising an ebullating bed reactor operating in gas and liquid upflow mode and containing at least one supported hydroconverting catalyst,   a zone for fractionation by atmospheric distillation,   a first section for hydrotreating in the presence of hydrogen, comprising a fixed bed reactor containing at least one hydrotreating catalyst,   a second section for hydrotreating in the presence of hydrogen, comprising at least one fixed bed reactor containing at least one hydrotreating catalyst,   a section for hydrocracking in the presence of hydrogen,   these elements being arranged for the implementation of the method according to  claim 1 .