Conversion process comprising permutable hydrodemetallization guard beds, a fixed-bed hydrotreatment step and a hydrocracking step in permutable reactors

1. Continuous process for treating a hydrocarbon-containing feedstock containing at least one hydrocarbon-containing 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., the process comprising the following stages:

a) a hydrodemetallization stage in which at least two permutable reactors are utilized at a temperature comprised between 300° C. and 500° C., and under an absolute pressure comprised between 5 MPa and 35 MPa, in the presence of the hydrocarbon-containing feedstock and hydrogen, and of a hydrodemetallization catalyst; by “permutable reactors” is meant a set of at least two reactors, one reactor of which can be stopped, generally for regeneration or replacement of the catalyst or for maintenance, while the other (or others) is (are) operating,

b) a fixed-bed hydrotreatment stage comprising at least one reactor in which the effluent originating from stage a) when this exists, or the hydrocarbon-containing feedstock directly when stage a) does not exist, is brought into contact with at least one hydrotreatment catalyst at a temperature comprised between 300° C. et 500° C. and under an absolute pressure comprised between 5 MPa et 35 MPa,

c) a fixed-bed hydrocracking stage in which at least two permutable reactors are implemented at a temperature comprised between 340° C. and 480° C., and under an absolute pressure comprised between 5 MPa and 35 MPa, in the presence of the effluent originating from stage b), and a hydrocracking catalyst,

d) a stage of separation of the effluent originating from stage c), in order to obtain at least one gaseous fraction and at least one heavy liquid fraction,

e) a stage of precipitation of the sediments contained in the heavy liquid fraction originating from stage d) which can be carried out according to 3 variants called destabilization (e1), oxidation (e2), or oxidizing destabilization (e3), the operating conditions common to the three variants being the following:

residence time less than 60 minutes,

temperature between 80 and 250° C.,

pressure less than 1.5 MPa,

f) a stage of physical separation of the sediments of the heavy liquid fraction originating from stage e) of precipitation in order to obtain a fraction containing the sediments, and a liquid hydrocarbon-containing fraction having a reduced sediment content,

g) a stage of recovery of a liquid hydrocarbon-containing fraction having a sediment content after ageing of less than or equal to 0.1% by weight consisting of separating the liquid hydrocarbon-containing fraction having a reduced sediment content originating from stage f) from the distillate cut introduced during stage e) and which is recycled to said stage e).

2. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which the hydrodemetallization stage a) is conducted under the following operating conditions:

temperature preferably comprised between 350° C. and 430° C.,

absolute pressure comprised between 11 MPa and 26 MPa, and

volumetric flow rate of the feedstock is between 0.1 h −1 and 5 h −1 .

3. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which the hydrodemetallization stage a) uses a hydrodemetallization catalyst comprising from 0.5 to 10% by weight of nickel (expressed as nickel oxide NiO) and from 1 to 30% by weight of molybdenum (expressed as molybdenum oxide MoO 3 ) on a mineral support.

4. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which hydrotreatment stage b) is carried out at a temperature comprised between 350° C. and 430° C., and under an absolute pressure comprised between 14 MPa and 20 MPa.

5. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which the hydrotreatment stage b) uses a catalyst comprising from 0.5 to 10% by weight of nickel (expressed as nickel oxide NiO) and from 1 to 30% by weight of molybdenum (expressed as molybdenum oxide MoO 3 ) on a mineral support selected from the group constituted by alumina, silica, silica-aluminas, magnesium oxide, clays and mixtures of at least two of these minerals.

6. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which hydrocracking stage c) is carried out at a temperature comprised between 350° C. and 430° C., and under an absolute pressure comprised between 14 MPa and 20 MPa.

7. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which hydrocracking stage c) uses a catalyst comprising from 0.5 to 10% by weight of nickel (expressed as nickel oxide NiO) and from 1 to 30% by weight of molybdenum (expressed as molybdenum oxide MoO 3 ) on a mineral support selected from the group constituted by alumina, silica, silica-aluminas, magnesium oxide, clays and mixtures of at least two of these minerals.

8. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which separation stage d) comprises at least one atmospheric distillation which makes it possible to obtain at least one atmospheric distillate fraction and at least one atmospheric residue fraction.

9. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which separation stage d) comprises at least one vacuum distillation which makes it possible to obtain at least one vacuum distillate fraction and at least one vacuum residue fraction.

10. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which stage e) of precipitation of the sediments is carried out by destabilization, i.e. by bringing the heavy liquid fraction originating from separation stage d) into contact with a distillate cut comprising from 3 to 40 carbon atoms, and more precisely at least 20% by weight of which has a boiling temperature greater than or equal to 150° C.

11. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which the distillate cut used for bringing into contact with the heavy liquid fraction originating from stage d) is selected from the following cuts used alone or in a mixture: cuts of the propane, butane, pentane, hexane, heptane, naphtha or kerosene type, atmospheric gasoil or vacuum gasoil.

12. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which stage e) of precipitation of the sediments is carried out according to a variant known as “by oxidation”, i.e. by bringing the heavy liquid fraction originating from separation stage d) into contact with a gaseous, liquid or solid oxidizing compound, for example a peroxide such as oxygenated water, or also a mineral oxidizing solution such as a solution of potassium permanganate or a mineral acid such as sulphuric acid.

13. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which stage e) of precipitation of the sediments is carried out according to a variant known as oxidizing destabilization i.e. by bringing the heavy liquid fraction originating from separation stage d) into contact with a distillate cut as defined in the variant of precipitation by destabilization and a gaseous, liquid or solid oxidizing compound as defined in the variant of precipitation by oxidation.

14. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which stage f) of physical separation of the sediments uses a physical separation means selected from a filter, a separation membrane, a filtering bed of organic- or inorganic-type solids, electrostatic precipitation, an electrostatic filter, a centrifugation system, a centrifugal decanter, a draw-off by means of an endless screw.

15. Process for the treatment of a hydrocarbon-containing feedstock according to claim 1 , in which stage g) of recovery of the liquid hydrocarbon-containing fraction having a sediment content after ageing of less than or equal to 0.1% by weight consists of separating the liquid hydrocarbon-containing fraction having a reduced sediment content originating from stage f) from the distillate cut introduced during stage e), which is recycled to stage e).