Method for converting residues incorporating deep hydroconversion steps and a deasphalting step

Abstract

The invention concerns a method for converting heavy hydrocarbon feedstocks of which at least 50% by weight boils at a temperature of at least 300° C., and in particular vacuum residues. The feedstocks are subjected to a first step a) of deep hydroconversion, optionally followed by a step b) of separating a light fraction, and a heavy residual fraction is obtained from step b) of which at least 80% by weight has a boiling temperature of at least 250° C. Said fraction from step b) or the effluent from step a) is then subjected to a second step c) of deep hydroconversion. The overall hourly space velocity for steps a) to c) is less than 0.1 h.sup.−1. The effluent from step c) is fractionated to separate a light fraction. The heavy fraction obtained, of which 80% by weight boils at a temperature of at least 300° C., is sent to a deasphalting step e). The deasphalted fraction DAO is then preferably converted in a step f) chosen from ebullated bed hydroconversion, fluidised bed catalytic cracking and fixed bed hydrocracking.

Claims

1. A process for the conversion of hydrocarbon feedstocks, at least 50% by weight of which boils at a temperature of at least 300° C., comprising the following successive stages: stage a), a first deep hydroconversion of said hydrocarbon feedstock in the presence of hydrogen, under an absolute pressure of between 2 MPa and 35 MPa, at a temperature of between 300° C. and 550° C., with an amount of hydrogen of between 50 Sm.sup.3/m.sup.3 and 5000 Sm.sup.3/m.sup.3, with a catalyst containing at least one nickel or cobalt Group VIII metal and at least one molybdenum or tungsten Group VIb metal, stage b) separation of a light fraction from a part or all of effluent resulting from said first deep hydroconversion, and obtaining at least one heavy fraction, at least 80% by weight of which exhibits a boiling point of at least 250° C., by one or more flash drums in series, or by one or more steam stripping and/or hydrogen stripping columns, or by an atmospheric distillation column, alone or followed by a vacuum distillation column, or by a combination thereof, stage c), a second deep hydroconversion of a part or all of the heavy fraction resulting from stage b) in the presence of hydrogen, under an absolute pressure of between 2 MPa and 35 MPa, at a temperature of between 300° C. and 550° C., with an amount of hydrogen of between 50 Sm.sup.3/m.sup.3 and 5000 Sm.sup.3/m.sup.3, with a catalyst containing at least one nickel or cobalt Group VIII metal and at least one molybdenum or tungsten Group VIb metal, the overall hourly space velocity for stages a) to c) being 0.05-0.09 h.sup.−1, the overall velocity being the flow rate of liquid feedstock of the hydroconversion stage a), taken under standard temperature and pressure conditions, with respect to the total volume of the reactors of stages a) and c), stage d) separation of a part or all of effluent resulting from said second hydroconversion into at least one light fraction and at least one heavy fraction, at least 80% by weight of which exhibits a boiling point of at least 300° C., stage e) deasphalting said heavy fraction resulting from stage d), at a temperature of between 60° C. and 250° C., with at least one hydrocarbon solvent having from 3 to 7 carbon atoms, and a solvent/feedstock ratio (volume/volume) of between 4/1 and 9/1, obtaining a deasphalted fraction DAO and an asphalt stage f) after optionally distilling, and optionally preliminarily hydrotreating, converting all or a part of the optionally distilled, optionally hydrotreated deasphalted fraction DAO, in a conversion stage operating by fluidized-bed catalytic cracking in the presence of a catalyst comprising alumina, silica, silica/alumina, and optionally comprising at least one zeolite.

2. The process as claimed in claim 1, in which the DAO is distilled before the conversion stage f), so as to separate a heavy fraction, at least 80% by weight of which exhibits a boiling point of at least 375° C., and said heavy fraction sent, in part or in its entirety, into the conversion stage f).

3. The process as claimed in claim 1, in which a part or all of the DAO fraction is sent directly into the conversion stage operating by fluidized-bed catalytic cracking.

4. The process as claimed in claim 1, in which a part or all of the deasphalted fraction DAO is subjected to a fluidized-bed catalytic cracking FCC in the presence of a catalyst comprising alumina, silica, silica/alumina, and comprising at least one zeolite.

5. The process as claimed in claim 1, in which at least a part of said deasphalted fraction DAO is recycled to stage a) and/or to stage c).

6. The process as claimed in claim 1, in which, in the separation stage d), the effluent resulting from said second hydroconversion is separated into at least one light fraction and at least one heavy fraction, at least 80% by weight of which exhibits a boiling point of at least 375° C.

7. The process as claimed in claim 1, in which: stages a) and c) are carried out under an absolute pressure of between 5 MPa and 25 MPa and at a temperature of between 350° C. and 500° C., with an amount of hydrogen of between 100 Sm.sup.3/m.sup.3 and 2000 Sm.sup.3/m.sup.3, stage e) is carried out with a butane, pentane or hexane solvent, or a mixture thereof.

8. The process as claimed in claim 1, wherein in f) the HSV of DAO in the conversion stage is 0.15 h.sup.−1 to 2 h.sup.−1.

Description

DESCRIPTION OF THE FIGURE

(1) FIG. 1 illustrates the invention.

(2) It comprises a deep hydroconversion section A in which the deep hydroconversion stage a) is carried out. The feedstock 1 is converted in the presence of hydrogen 2 and the resulting effluent 3 is separated (stage b), optionally followed by stage b′)) in the separation section B. A light fraction 4 and a heavy fraction 5 are obtained. The latter is sent into the deep hydroconversion section C, where it is subjected to the stage c) of deep hydroconversion in the presence of hydrogen 6. A light fraction 8 and a heavy fraction 9 are separated from the resulting effluent 7 and the heavy fraction 9 is directed to the deasphalting section E where the deasphalting stage e) is carried out using a solvent 12. The deasphalted oil DAO 10 is sent to a conversion section F where the conversion stage f) takes place and the asphalt 11 is recovered. The effluent 13 resulting from the conversion stage f) is subsequently generally sent into a separation stage, so as to recover the economically enhanceable cuts, for example gasoline and gas oil.

EXAMPLES

(3) Examples 1 and 2 are compared at the same conversion (75% of 540° C.+ into 540° C.−) and examples 3 and 4 are carried out at the same temperature. Examples 5 and 6 are compared at the same conversion (75% of 540° C.+ into 540° C.−) and examples 7 and 8 are carried out at the same temperature.

(4) Feedstock

(5) The heavy feedstock is a vacuum residue (VR) originating from a Urals crude oil, the main characteristics of which are presented in table 1 below. This VR heavy feedstock is the same fresh feedstock for the different examples.

(6) TABLE-US-00002 TABLE 1 Composition of the feedstock of the process Feedstock of stage A Feedstock Urals VR Density 1.000 540° C. + content % by weight 77.9 Viscosity at 100° C. cSt 880 Conradson carbon % by weight 17.0 C.sub.7 Asphaltenes % by weight 6.8 Nickel + Vanadium ppm 233 Nitrogen ppm 6010 Sulfur % by weight 2.715

Example 1 not in Accordance with the Invention

(7) Scheme having a high hourly space velocity and high temperature (overall HSV=0.3 h.sup.−1+431/431° C.)+deasphalting stage (SDA)

(8) In this example, two ebullating-bed reactors (first and second deep hydroconversion section) are positioned in series, operated at high hourly space velocity (HSV) and high temperature with an inter-step separation section and a downstream deasphalting process.

(9) Hydroconversion Section A

(10) The fresh feedstock of table 1 is sent in its entirety into the first ebullating-bed hydroconversion section A, in the presence of hydrogen, which section comprises a three-phase reactor a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas.

(11) The conditions applied in the hydroconversion section A are presented in table 2.

(12) TABLE-US-00003 TABLE 2 Operating conditions of the hydroconversion section A Section A Total P MPa 16 Temperature ° C. 431 Amount of hydrogen Sm.sup.3/m.sup.3 500

(13) These operating conditions make it possible to obtain a liquid effluent having a reduced content of Conradson carbon, of metals and of sulfur.

(14) Separation Section B

(15) The liquid effluent resulting from section A is subsequently sent into a separation section B composed of a single gas/liquid separator operating at the pressure and at the temperature of the reactor of the first hydroconversion section A. A “light” fraction and a “heavy” fraction are thus separated. The “light” fraction is predominantly composed of molecules having a boiling point of less than 350° C. and the “heavy” fraction is predominantly composed of hydrocarbon molecules boiling at a temperature of at least 350° C.

(16) Hydroconversion Section C

(17) The heavy fraction resulting from the separation section B is sent, alone and in its entirety, into a second hydroconversion section C in the presence of hydrogen. Said section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas.

(18) The conditions applied in the hydroconversion section C are presented in table 4.

(19) TABLE-US-00004 TABLE 4 Operating conditions of the hydroconversion section C Section C Total P MPa 15.6 Temperature ° C. 431 Amount of hydrogen Sm.sup.3/m.sup.3 300
Fractionation Section D

(20) The effluent from the hydroconversion section C is sent into a fractionation section D composed of an atmospheric distillation, followed by a vacuum distillation, from which an unconverted vacuum residue (VR) heavy fraction boiling at a temperature of at least 540° C. is recovered, the yields with respect to the fresh feedstock and the quality of which are given in table 5 below.

(21) TABLE-US-00005 TABLE 5 Yield and quality of the VR resulting from the fractionation section D Unconverted vacuum Fraction residue Yield with respect to the % by weight 19.42 fresh feedstock (A) 540° C. + content % by weight 100 Density g/cm.sup.3 1.0157 Conradson carbon % by weight 22.2 Nickel + Vanadium ppm 91.4 Nitrogen ppm 8870 Sulfur % by weight 1.028 Saturates % by weight 15.5 Aromatics % by weight 36.2 Resins % by weight 38.9 C.sub.7 Asphaltenes % by weight 9.4
Deasphalting Section E

(22) The vacuum residue resulting from section D is sent into the deasphalting section E. The conditions applied in the deasphalting unit are described in table 6.

(23) TABLE-US-00006 TABLE 6 Operating conditions in the SDA unit E Vacuum residue resulting from Feedstock section D Solvent Butane Extractor pressure MPa 3.0 T.sub.mean extractor ° C. 95 Solvent/feedstock ratio v/v 8

(24) On conclusion of section E, a DAO fraction, which can be economically enhanced in a conversion process (fixed-bed hydrocracking, FCC or recycling to the process for hydroconversion under mild conditions in an ebullating bed), and an “asphalt” fraction, which is difficult to economically enhance, are obtained. The yields and qualities of these two products are given in table 7.

(25) TABLE-US-00007 TABLE 7 Yields and qualities of the effluents resulting from the deasphalting section E Fraction DAO Asphalt Yield with respect to the % by weight 49.9 50.1 unconverted VR (D) Yield with respect to the % by weight 9.7  9.7 fresh feedstock (A) Density g/cm.sup.3 0.9474   1.0942 Conradson carbon % by weight 7.42 36.9 C.sub.7 Asphaltenes % by weight 0.09 18.7 Nickel + Vanadium ppm <2 181   Nitrogen ppm 4520 13 210    Sulfur % by weight 0.836   1.220
Overall Performance Qualities

(26) With this scheme not in accordance with the invention, for an overall hourly space velocity (HSV) of 0.3 h.sup.−1 and high temperatures (431/431° C.), the conversion of the heavy 540° C.+ cut is 75.1% by weight before the deasphalting stage. Furthermore, the unconverted VR contains high contents of Conradson carbon and C.sub.7 asphaltenes (respectively 22.2% by weight and 9.4% by weight), implying that only 49.9% by weight of the unconverted VR is recoverable in the form of DAO. Thus, this conventional scheme is accompanied by a significant generation of asphalt of 9.7% by weight, with respect to the fresh starting feedstock. If the DAO cut is subsequently completely converted in a hydrocracking unit, the total conversion of the heavy 540° C.+ cut in the complete scheme is 87.5% by weight.

Example 2 According to the Invention

(27) Scheme according to the invention having a low hourly space velocity (overall HSV=0.089 h.sup.−1+411/411° C.) and having a low temperature+SDA

(28) In this example, the present invention is illustrated in a process scheme with two ebullating-bed reactors positioned in series, operated at low hourly space velocity (HSV=0.089 h.sup.−1) and at low temperature (411/411° C.) and with an inter-step separation section and a downstream deasphalting process, as described in connection with FIG. 1.

(29) Hydroconversion Section A

(30) The fresh feedstock of table 1 is sent in its entirety into the first ebullating-bed hydroconversion section A, in the presence of hydrogen, which section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas.

(31) The conditions applied in the hydroconversion section A are presented in table 8.

(32) TABLE-US-00008 TABLE 8 Operating conditions of the hydroconversion section A Section A Total P MPa 16 Temperature ° C. 411 Amount of hydrogen Sm.sup.3/m.sup.3 600
Separation Section B

(33) The liquid effluent resulting from section A is subsequently sent into a separation section B composed of a single gas/liquid separator operating at the pressure and at the temperature of the reactors of the first hydroconversion section A. A “light” fraction and a “heavy” fraction are thus separated. The “light” fraction is predominantly composed of molecules having a boiling point of less than 350° C. and the “heavy” fraction is predominantly composed of hydrocarbon molecules boiling at a temperature of at least 350° C.

(34) Hydroconversion Section C

(35) The heavy fraction resulting from the separation section B is sent, alone and in its entirety, into a second ebullating-bed hydroconversion section C, in the presence of hydrogen. Said section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas.

(36) These operating conditions make it possible to obtain a liquid effluent having a reduced content of Conradson carbon, of metals and of sulfur.

(37) The conditions applied in the hydroconversion section C are presented in table 9.

(38) TABLE-US-00009 TABLE 9 Operating conditions of the hydroconversion section C Section C Total P MPa 15.6 Temperature ° C. 411 Amount of hydrogen Sm.sup.3/m.sup.3 250
Fractionation Section D

(39) The effluent from the hydroconversion section C is sent into a fractionation section D composed of an atmospheric distillation, followed by a vacuum distillation, from which an unconverted vacuum residue (VR) heavy fraction boiling at a temperature of at least 540° C. is recovered, the yields with respect to the fresh feedstock and the quality of which are given in table 10 below.

(40) TABLE-US-00010 TABLE 10 Yield and quality of the VR resulting from the fractionation section D Unconverted vacuum Fraction residue Yield with respect to the % by weight 19.33 fresh feedstock (A) Content of 540° C.+ % by weight 100 Density g/cm.sup.3 0.9924 Conradson carbon % by weight 16.4 Nickel + Vanadium ppm 21.7 Nitrogen ppm 7120 Sulfur % by weight 0.687 Saturates % by weight 19.0 Aromatics % by weight 41.6 Resins % by weight 34.9 C.sub.7 Asphaltenes % by weight 4.6
Deasphalting Section E

(41) The vacuum residue resulting from section D is sent into the deasphalting section E. The conditions applied in the deasphalting unit described in table 11.

(42) TABLE-US-00011 TABLE 11 Operating conditions in the SDA unit E Vacuum residue resulting from Feedstock section D Solvent butane Extractor pressure MPa 3.0 T.sub.mean extractor ° C. 95 Solvent/feedstock ratio v/v 8

(43) On conclusion of section E, a DAO fraction, which can be economically enhanced in a conversion process (fixed-bed hydrocracking, FCC or recycling to the process for hydroconversion under mild conditions in an ebullating bed), and an “asphalt” fraction, which is difficult to economically enhance, are obtained.

(44) The yields and qualities of these two products are given in table 12.

(45) TABLE-US-00012 TABLE 12 Yields and qualities of the effluents resulting from the deasphalting section E Fraction DAO Asphalt Yield with respect to the % by weight 68.2 31.8 unconverted VR (D) Yield with respect to the % by weight 13.2  6.1 fresh feedstock (A) Density g/cm.sup.3 0.9495   1.0988 Conradson carbon % by weight 8.1 34.1 C.sub.7 Asphaltenes % by weight 0.07 14.2 Nickel + Vanadium ppm <2 67.4 Nitrogen ppm 4590 12 530    Sulfur % by weight 0.610   0.849
Overall Performance Qualities

(46) With this scheme according to the invention having an overall HSV=0.089 h.sup.−1, the conversion of the heavy 540° C.+ cut is 75.2% by weight before the deasphalting stage, i.e. comparable to example 1. However, the unconverted VR contains lower contents of Conradson carbon and C.sub.7 asphaltenes in comparison with example 1, which makes it possible to recover a greater amount of DAO from the unconverted VR (68.2% by weight recoverable in this example, versus 49.9% by weight in example 1). Thus, this scheme according to the invention is accompanied by a lower generation of asphalt corresponding to 6.1% by weight, with respect to the fresh starting feedstock. If all of the DAO is converted in a hydrocracking unit, then an overall conversion of 92.1% by weight of the starting heavy 540° C.+ cut can thus be obtained by virtue of this example according to the invention, i.e. 4.6 conversion points more than in example 1. The scheme according to the invention thus makes it possible to exceed a conversion of 90% by weight, with respect to the fresh feedstock.

Example 3 not in Accordance with the Invention

(47) Scheme having a high hourly space velocity and having a moderate temperature (overall HSV=0.3 h.sup.−1+420/420° C.)+SDA deasphalting stage

(48) In this example, the operation is carried out with two ebullating-bed reactors positioned in series (first and second deep hydroconversions), which are operated at high hourly space velocity (HSV) and at moderate temperature (420° C.) with an inter-step separation section and a downstream deasphalting process.

(49) Hydroconversion Section A

(50) The fresh feedstock of table 1 is sent, in its entirety, into an ebullating-bed hydroconversion section A, in the presence of hydrogen. The three-phase reactor contains a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas.

(51) The conditions applied in the hydroconversion section A are presented in table 13.

(52) TABLE-US-00013 TABLE 13 Operating conditions of the hydroconversion section A Section A Total P MPa 16 Temperature ° C. 420 Amount of hydrogen Sm.sup.3/m.sup.3 350

(53) These operating conditions make it possible to obtain a liquid effluent having a reduced content of Conradson carbon, of metals and of sulfur.

(54) Separation Section B

(55) The liquid effluent resulting from section A is subsequently sent into a separation section B composed of a single gas/liquid separator operating at the pressure and at the temperature of the reactors of the first hydroconversion section A. A “light” fraction and a “heavy” fraction are thus separated. The “light” fraction is predominantly composed of molecules having a boiling point of less than 350° C. and the “heavy” fraction is predominantly composed of hydrocarbon molecules boiling at a temperature of at least 350° C.

(56) Hydroconversion Section C

(57) The heavy fraction resulting from the separation section B is sent, alone and in its entirety, into a second ebullating-bed hydroconversion section C, in the presence of hydrogen. Said section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas.

(58) The conditions applied in the hydroconversion section C are presented in table 14.

(59) TABLE-US-00014 TABLE 14 Operating conditions of the hydroconversion section C Section C Total P MPa 15.6 Temperature ° C. 420 Amount of hydrogen Sm.sup.3/m.sup.3 200
Fractionation Section D

(60) The effluent from the hydroconversion section C is sent into a fractionation section D composed of an atmospheric distillation, followed by a vacuum distillation, from which an unconverted vacuum residue (VR) heavy fraction boiling at a temperature of at least 540° C. is recovered, the yields with respect to the fresh feedstock and the quality of which are given in table 15 below.

(61) TABLE-US-00015 TABLE 15 Yield and quality of the VR resulting from the fractionation section D Unconverted Fraction vacuum residue Yield with respect to the % by weight 31.75 fresh feedstock (A) 540° C. + content % by weight 100 Density g/cm.sup.3 1.0098 Conradson carbon % by weight 20.7 Nickel + Vanadium ppm 98.0 Nitrogen ppm 8230 Sulfur % by weight 1.246 Saturates % by weight 16.4 Aromatics % by weight 37.5 Resins % by weight 37.9 C.sub.7 Asphaltenes % by weight 8.2
Deasphalting Section E

(62) The vacuum residue resulting from section D is sent into the deasphalting section E.

(63) The conditions applied in the deasphalting unit described in table 16.

(64) TABLE-US-00016 TABLE 16 Operating conditions in the SDA unit E Feedstock Vacuum residue resulting from section D Solvent butane Extractor pressure MPa 3.0 T.sub.mean extractor ° C. 95 Solvent/feedstock ratio v/v 8

(65) On conclusion of section E, a DAO fraction, which can be economically enhanced in a conversion process (hydrocracking, FCC or recycling to the hydroconversion process), and an “asphalt” fraction, which is difficult to economically enhance, are obtained. The yields and qualities of these two products are given in table 17.

(66) TABLE-US-00017 TABLE 17 Yields and qualities of the effluents resulting from the deasphalting section E Fraction DAO Asphalt Yield with respect to the % by weight 54.1 45.9 unconverted VR Yield with respect to the % by weight 17.2 14.6 fresh feedstock (A) Density g/cm.sup.3 0.9478   1.0943 Conradson carbon % by weight 7.53 36.3 C.sub.7 Asphaltenes % by weight 0.08 17.8 Nickel + Vanadium ppm <2 212.4  Nitrogen ppm 4420 12 730    Sulfur % by weight 1.036   1.493
Overall Performance Qualities

(67) With this scheme, for an overall hourly space velocity (HSV) of 0.3 h.sup.−1 and moderate temperatures (420/420° C.), the conversion of the heavy 540° C.+ cut is 59.2% by weight before the deasphalting stage. Furthermore, the unconverted VR contains high contents of Conradson carbon and 07 asphaltenes (respectively 20.7% by weight and 8.2% by weight), implying that only 54.1% by weight of the unconverted VR is recoverable in the form of DAO. Thus, this conventional scheme is accompanied by a significant generation of asphalt of 14.6% by weight, with respect to the fresh starting feedstock. Even if all of the DAO is converted in a hydrocracking unit, this sequence according to the prior art only corresponds to an overall conversion of 81.3% by weight of the starting heavy 540° C.+ cut. It thus does not make it possible to achieve levels of conversion of the heavy 540° C.+ cut of greater than 90% by weight.

Example 4 According to the Invention

(68) Scheme according to the invention having a low hourly space velocity (overall HSV=0.089 h.sup.−1+420/420° C.) and having a low temperature+SDA deasphalting stage

(69) In this example, the present invention is illustrated in a process scheme with two ebullating-bed reactors positioned in series, operated at low hourly space velocity (HSV=0.089 h.sup.−1) and at moderate temperature (420/420° C.) and with an inter-step separation section and a downstream deasphalting process, according to the scheme of FIG. 1.

(70) Hydroconversion Section A

(71) The fresh feedstock of table 1 is sent, in its entirety, into an ebullating-bed hydroconversion section A, in the presence of hydrogen. Said section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas. The conditions applied in the hydroconversion section A are presented in table 18.

(72) TABLE-US-00018 TABLE 18 Operating conditions of the hydroconversion section A Section A Total P MPa 16 Temperature ° C. 420 Amount of hydrogen Sm.sup.3/m.sup.3 700

(73) These operating conditions make it possible to obtain a liquid effluent having a reduced content of Conradson carbon, of metals and of sulfur.

(74) Separation Section B

(75) The liquid effluent resulting from section A is subsequently sent into a separation section B composed of a single gas/liquid separator operating at the pressure and at the temperature of the reactors of the first hydroconversion section A. A “light” fraction and a “heavy” fraction are thus separated. The “light” fraction is predominantly composed of molecules having a boiling point of less than 350° C. and the “heavy” fraction is composed of hydrocarbon molecules boiling at a temperature of at least 350° C.

(76) Hydroconversion Section C

(77) In this reference scheme, the heavy fraction resulting from the separation section B is sent, alone and in its entirety, into a second ebullating-bed hydroconversion section C, in the presence of hydrogen. Said section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas. The conditions applied in the hydroconversion section C are presented in table 19.

(78) TABLE-US-00019 TABLE 19 Operating conditions of the hydroconversion section C Section C Total P MPa 15.6 Temperature ° C. 420 Amount of hydrogen Sm.sup.3/m.sup.3 350
Fractionation Section D

(79) The effluent from the hydroconversion section C is sent into a fractionation section D composed of an atmospheric distillation, followed by a vacuum distillation, from which an unconverted vacuum residue (VR) heavy fraction boiling at a temperature of at least 540° C. is recovered, the yields with respect to the fresh feedstock and the quality of which are given in table 20 below.

(80) TABLE-US-00020 TABLE 20 Yield and quality of the VR resulting from the fractionation section D Unconverted vacuum Fraction residue Yield with respect to the % by weight 10.8 fresh feedstock (A) Content of 540° C.+ % by weight 100 Density g/cm.sup.3 0.9952 Conradson carbon % by weight 17.05 Nickel + Vanadium ppm 19.4 Nitrogen ppm 7350 Sulfur % by weight 0.582 Saturates % by weight 18.5 Aromatics % by weight 41.4 Resins % by weight 35.4 C.sub.7 Asphaltenes % by weight 4.8
Deasphalting Section (E)

(81) The vacuum residue resulting from section D is sent into the deasphalting section E. The conditions applied in the deasphalting unit described in table 21.

(82) TABLE-US-00021 TABLE 21 Operating conditions in the SDA unit E Vacuum residue resulting from Feedstock section D Solvent butane Extractor pressure MPa 3.0 T.sub.mean extractor ° C. 95 Solvent/feedstock ratio v/v 8

(83) On conclusion of section E, a DAO fraction, which can be economically enhanced in a conversion process (hydrocracking, FCC or recycling to the hydroconversion process), and an “asphalt” fraction, which is difficult to economically enhance, are obtained. The yields and qualities of these two products are given in table 22.

(84) TABLE-US-00022 TABLE 22 Yields and qualities of the effluents resulting from the deasphalting section E Fraction DAO Asphalt Yield with respect to the % by weight 66.8 33.2 unconverted VR Yield with respect to the % by weight 7.2  3.6 fresh feedstock (A) Density g/cm.sup.3 0.9505   1.0995 Conradson carbon % by weight 8.3 34.6 C.sub.7 Asphaltenes % by weight 0.07 14.2 Nickel + Vanadium ppm <2 57.9 Nitrogen ppm 4670 12 750    Sulfur % by weight 0.515   0.716
Overall Performance Qualities

(85) With this scheme according to the invention having an overall HSV=0.089 h.sup.−1 and having a moderate temperature (420/420° C.), the conversion of the heavy 540° C.+ cut is 86.1% by weight before the deasphalting stage, i.e. greater by 26.9% by weight with respect to example 3 at the same temperature level. The amount of unconverted VR recovered in example 4 is thus approximately 3 times lower. Moreover, the unconverted VR of example 4 contains lower contents of Conradson carbon and C.sub.7 asphaltenes in comparison with example 3, which makes it possible to recover a greater amount of DAO from the unconverted VR (66.8% by weight recoverable in this example, versus 54.1% by weight in example 3). Thus, this scheme according to the invention is accompanied by a lower generation of asphalt corresponding to only 3.6% by weight, with respect to the fresh starting feedstock. If all of the DAO is converted in a hydrocracking unit, a very high conversion of the starting heavy 540° C.+ cut of 95.4% by weight can thus be obtained by virtue of this scheme according to the invention.

Example 5 not in Accordance with the Invention

(86) Scheme having a high hourly space velocity and high temperature (overall HSV=0.3 h.sup.−1+431/431° C.)+deasphalting stage (SDA)+stage of conversion of the DAO in FCC

(87) In this example, two ebullating-bed reactors (first and second deep hydroconversion section) are positioned in series, operated at high hourly space velocity (HSV) and high temperature with an inter-step separation section and a downstream deasphalting process. The DAO cut is subsequently converted in an FCC unit.

(88) Hydroconversion Section (A)

(89) The fresh feedstock of table 1 is sent in its entirety into the first ebullating-bed hydroconversion section A, in the presence of hydrogen, which section comprises a three-phase reactor a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas. The conditions applied in the hydroconversion section A are presented in table 2. These operating conditions make it possible to obtain a liquid effluent having a reduced content of Conradson carbon, of metals and of sulfur.

(90) Separation Section (B)

(91) The liquid effluent resulting from section A is subsequently sent into a separation section B composed of a single gas/liquid separator operating at the pressure and at the temperature of the reactor of the first hydroconversion section A. A “light” fraction and a “heavy” fraction are thus separated. The “light” fraction is predominantly composed of molecules having a boiling point of less than 350° C. and the “heavy” fraction is predominantly composed of hydrocarbon molecules boiling at a temperature of at least 350° C.

(92) Hydroconversion Section (C)

(93) The heavy fraction resulting from the separation section B is sent, alone and in its entirety, into a second hydroconversion section C in the presence of hydrogen. Said section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas. The conditions applied in the hydroconversion section C are presented in table 4.

(94) Fractionation Section (D)

(95) The effluent from the hydroconversion section C is sent into a fractionation section D composed of an atmospheric distillation, followed by a vacuum distillation, from which an unconverted vacuum residue (VR) heavy fraction boiling at a temperature of at least 540° C. is recovered, the yields with respect to the fresh feedstock and the quality of which are given in table 5.

(96) Deasphalting Section (E)

(97) The vacuum residue resulting from section D is sent into the deasphalting section E. The conditions applied in the deasphalting unit are described in table 6. On conclusion of section E, a DAO fraction and an “asphalt” fraction, which is difficult to economically enhance, are obtained. The yields and qualities of these two products are given in table 7.

(98) Section for Conversion of the DAO (F)

(99) The DAO fraction resulting from the deasphalting section E is subsequently sent to a fluidized-bed catalytic cracking unit, also known as FCC unit. This conversion unit makes it possible to transform the DAO fraction, which is a 540° C.+ cut, into lighter fractions. This thus makes it possible to increase the overall conversion of the starting feedstock (the vacuum residue (VR) originating from a Urals crude oil, the characteristics of which are presented in table 1). On the other hand, the liquid fraction resulting from the FCC unit still contains a slight unconverted 540° C.+ fraction, the yield of which is 1.1% by weight, with respect to the feedstock of the FCC, as indicated in table 23. Compared with example 1, where all the DAO was converted in a hydrocracking unit, the conversion of the DAO is in this instance not total.

(100) TABLE-US-00023 TABLE 23 Yields and qualities of the effluents resulting from the FCC unit F Unit FCC Yield Gasoline (C.sub.5-220° C.) % by weight 40.9 Yield Gas Oil (220-360° C.) % by weight 14.2 Yield Vacuum Distillate (360-540° C.) % by weight 14.2 Yield Vacuum Residue (540° C.+) % by weight 1.1
Overall Performance Qualities

(101) With this scheme not in accordance with the invention, for an overall hourly space velocity (HSV) of 0.3 h.sup.−1 and high temperatures (431/431° C.), the conversion of the heavy 540° C.+ cut is 75.1% by weight before the deasphalting stage. The unconverted VR contains high contents of Conradson carbon and 07 asphaltenes (respectively 22.2% by weight and 9.4% by weight), implying that only 49.9% by weight of the unconverted VR is recoverable in the form of DAO. Thus, this conventional scheme is accompanied by a significant generation of asphalt of 9.7% by weight, with respect to the fresh starting feedstock. The DAO cut is in this instance converted in an FCC unit. With this sequential scheme not in accordance with the invention, for an overall hourly space velocity (HSV) of 0.30 h.sup.−1 and high temperatures (431/431° C.), the overall conversion of the heavy 540° C.+ cut in the complete scheme is 86.8% by weight.

Example 6 According to the Invention

(102) Scheme according to the invention having a low hourly space velocity (overall HSV=0.089 h.sup.−1+411/411° C.) and having a low temperature+deasphalting stage (SDA)+stage of conversion of the DAO in FCC

(103) In this example, the present invention is illustrated in a process scheme with two ebullating-bed reactors positioned in series, operated at low hourly space velocity (HSV=0.089 h.sup.−1) and at low temperature (411/411° C.) and with an inter-step separation section and a downstream deasphalting process, as described in connection with FIG. 1. The DAO cut is subsequently converted in an FCC unit.

(104) Hydroconversion Section (A)

(105) The fresh feedstock of table 1 is sent in its entirety into the first ebullating-bed hydroconversion section A, in the presence of hydrogen, which section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas. The conditions applied in the hydroconversion section A are presented in table 8.

(106) Separation Section (B)

(107) The liquid effluent resulting from section A is subsequently sent into a separation section B composed of a single gas/liquid separator operating at the pressure and at the temperature of the reactors of the first hydroconversion section A. A “light” fraction and a “heavy” fraction are thus separated. The “light” fraction is predominantly composed of molecules having a boiling point of less than 350° C. and the “heavy” fraction is predominantly composed of hydrocarbon molecules boiling at a temperature of at least 350° C.

(108) Hydroconversion Section (C)

(109) The heavy fraction resulting from the separation section B is sent, alone and in its entirety, into a second ebullating-bed hydroconversion section C, in the presence of hydrogen. Said section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas. These operating conditions make it possible to obtain a liquid effluent having a reduced content of Conradson carbon, of metals and of sulfur. The conditions applied in the hydroconversion section C are presented in table 9.

(110) Fractionation Section (D)

(111) The effluent from the hydroconversion section C is sent into a fractionation section D composed of an atmospheric distillation, followed by a vacuum distillation, from which an unconverted vacuum residue (VR) heavy fraction boiling at a temperature of at least 540° C. is recovered, the yields with respect to the fresh feedstock and the quality of which are given in table 10.

(112) Deasphalting Section (E)

(113) The vacuum residue resulting from section D is sent into the deasphalting section E. The conditions applied in the deasphalting unit described in table 11. On conclusion of section E, a DAO fraction and an “asphalt” fraction, which is difficult to economically enhance, are obtained. The yields and qualities of these two products are given in table 12.

(114) Section for Conversion of the DAO (F)

(115) The DAO fraction resulting from the deasphalting section E is subsequently sent to a fluidized-bed catalytic cracking unit, also known as FCC unit. This conversion unit makes it possible to transform the DAO fraction, which is a 540° C.+ cut, into lighter fractions. This thus makes it possible to increase the overall conversion of the starting feedstock (the vacuum residue (VR) originating from a Urals crude oil, the characteristics of which are presented in table 1). On the other hand, the liquid fraction resulting from the FCC unit still contains a slight unconverted 540° C.+ fraction, the yield of which is 1.2% by weight, with respect to the feedstock of the FCC, as indicated in table 24. Compared with example 2, where all the DAO was converted in a hydrocracking unit, the conversion of the DAO is in this instance not total.

(116) TABLE-US-00024 TABLE 24 Yields and qualities of the effluents resulting from the FCC unit F Unit FCC Yield Gasoline (C.sub.5-220° C.) % by weight 41.6 Yield Gas Oil (220-360° C.) % by weight 14.3 Yield Vacuum Distillate (360-540° C.) % by weight 15.2 Yield Vacuum Residue (540° C.+) % by weight 1.2
Overall Performance Qualities

(117) With this scheme according to the invention having an overall HSV=0.089 h.sup.−1, the conversion of the heavy 540° C.+ cut is 75.2% by weight before the deasphalting stage, i.e. comparable to example 5. However, the unconverted VR contains lower contents of Conradson carbon and C.sub.7 asphaltenes in comparison with example 5, which makes it possible to recover a greater amount of DAO from the unconverted VR (68.2% by weight recoverable in this example, versus 49.9% by weight in example 5). Thus, this scheme according to the invention is accompanied by a lower generation of asphalt corresponding to 6.1% by weight, with respect to the fresh starting feedstock. The DAO cut is in this instance converted in an FCC unit. With this sequential scheme according to the invention, for an overall hourly space velocity (HSV) of 0.089 h.sup.−1 and low temperatures (411/411° C.), the overall conversion of the heavy 540° C.+ cut in the complete scheme is 91.0% by weight, with respect to the starting heavy 540° C.+ cut, i.e. 4.2 conversion points more than in example 5. The scheme according to the invention thus makes it possible to exceed a conversion of 90% by weight, with respect to the fresh feedstock.

Example 7 not in Accordance with the Invention

(118) Scheme having a high hourly space velocity and having a moderate temperature (overall HSV=0.3 h.sup.−1+420/420° C.)+deasphalting stage (SDA)+stage of conversion of the DAO in FCC

(119) In this example, the operation is carried out with two ebullating-bed reactors positioned in series (first and second deep hydroconversions), which are operated at high hourly space velocity (HSV) and at moderate temperature (420° C.) with an inter-step separation section and a downstream deasphalting process. The DAO cut is subsequently converted in an FCC unit.

(120) Hydroconversion Section (A)

(121) The fresh feedstock of table 1 is sent, in its entirety, into an ebullating-bed hydroconversion section A, in the presence of hydrogen. The three-phase reactor contains a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas.

(122) The conditions applied in the hydroconversion section A are presented in table 13. These operating conditions make it possible to obtain a liquid effluent having a reduced content of Conradson carbon, of metals and of sulfur.

(123) Separation Section (B)

(124) The liquid effluent resulting from section A is subsequently sent into a separation section B composed of a single gas/liquid separator operating at the pressure and at the temperature of the reactors of the first hydroconversion section A. A “light” fraction and a “heavy” fraction are thus separated. The “light” fraction is predominantly composed of molecules having a boiling point of less than 350° C. and the “heavy” fraction is predominantly composed of hydrocarbon molecules boiling at a temperature of at least 350° C.

(125) Hydroconversion Section (C)

(126) The heavy fraction resulting from the separation section B is sent, alone and in its entirety, into a second ebullating-bed hydroconversion section C, in the presence of hydrogen. Said section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas. The conditions applied in the hydroconversion section C are presented in table 14.

(127) Fractionation Section (D)

(128) The effluent from the hydroconversion section C is sent into a fractionation section D composed of an atmospheric distillation, followed by a vacuum distillation, from which an unconverted vacuum residue (VR) heavy fraction boiling at a temperature of at least 540° C. is recovered, the yields with respect to the fresh feedstock and the quality of which are given in table 15.

(129) Deasphalting Section (E)

(130) The vacuum residue resulting from section D is sent into the deasphalting section E. The conditions applied in the deasphalting unit described in table 16. On conclusion of section E, a DAO fraction and an “asphalt” fraction, which is difficult to economically enhance, are obtained. The yields and qualities of these two products are given in table 17.

(131) Section for Conversion of the DAO (F)

(132) The DAO fraction resulting from the deasphalting section E is subsequently sent to a fluidized-bed catalytic cracking unit, also known as FCC unit. This conversion unit makes it possible to transform the DAO fraction, which is a 540° C.+ cut, into lighter fractions. This thus makes it possible to increase the overall conversion of the starting feedstock (the vacuum residue (VR) originating from a Urals crude oil, the characteristics of which are presented in table 1). On the other hand, the liquid fraction resulting from the FCC unit still contains a slight unconverted 540° C.+ fraction, the yield of which is 1.9% by weight, with respect to the feedstock of the FCC, as indicated in table 25. Compared with example 3, where all the DAO was converted in a hydrocracking unit, the conversion of the DAO is in this instance not total.

(133) TABLE-US-00025 TABLE 25 Yields and qualities of the effluents resulting from the FCC unit F Unit FCC Yield Gasoline (C.sub.5-220° C.) % by weight 30.9 Yield Gas Oil (220-360° C.) % by weight 16.7 Yield Vacuum Distillate (360-540° C.) % by weight 22.5 Yield Vacuum Residue (540° C.+) % by weight 1.9
Overall Performance Qualities

(134) With this scheme, for an overall hourly space velocity (HSV) of 0.3 h.sup.−1 and moderate temperatures (420/420° C.), the conversion of the heavy 540° C.+ cut is 59.2% by weight before the deasphalting stage. Furthermore, the unconverted VR contains high contents of Conradson carbon and 07 asphaltenes (respectively 20.7% by weight and 8.2% by weight), implying that only 54.1% by weight of the unconverted VR is recoverable in the form of DAO. Thus, this conventional scheme is accompanied by a significant generation of asphalt of 14.6% by weight, with respect to the fresh starting feedstock. The DAO cut is in this instance converted in an FCC unit. With this sequential scheme not in accordance with the invention, for an overall hourly space velocity (HSV) of 0.30 h.sup.−1 and moderate temperatures (420/420° C.), the overall conversion of the heavy 540° C.+ cut in the complete scheme is 80.0% by weight. This sequence according to the prior art thus does not make it possible to achieve levels of conversion of the heavy 540° C.+ cut of greater than 90% by weight.

Example 8 According to the Invention

(135) Scheme according to the invention having a low hourly space velocity (overall HSV=0.089 h.sup.−1+420/420° C.) and having a low temperature+deasphalting stage (SDA)+stage of conversion of the DAO in FCC

(136) In this example, the present invention is illustrated in a process scheme with two ebullating-bed reactors positioned in series, operated at low hourly space velocity (HSV=0.089 h.sup.−1) and at moderate temperature (420/420° C.) and with an inter-step separation section and a downstream deasphalting process, according to the scheme of FIG. 1. The DAO cut is subsequently converted in an FCC unit.

(137) Hydroconversion Section (A)

(138) The fresh feedstock of table 1 is sent, in its entirety, into an ebullating-bed hydroconversion section A, in the presence of hydrogen. Said section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas. The conditions applied in the hydroconversion section (A) are presented in table 18. These operating conditions make it possible to obtain a liquid effluent having a reduced content of Conradson carbon, of metals and of sulfur.

(139) Separation Section (B)

(140) The liquid effluent resulting from section A is subsequently sent into a separation section B composed of a single gas/liquid separator operating at the pressure and at the temperature of the reactors of the first hydroconversion section A. A “light” fraction and a “heavy” fraction are thus separated. The “light” fraction is predominantly composed of molecules having a boiling point of less than 350° C. and the “heavy” fraction is composed of hydrocarbon molecules boiling at a temperature of at least 350° C.

(141) Hydroconversion Section (C)

(142) In this reference scheme, the heavy fraction resulting from the separation section B is sent, alone and in its entirety, into a second ebullating-bed hydroconversion section C, in the presence of hydrogen. Said section comprises a three-phase reactor containing a NiMo/alumina hydroconversion catalyst exhibiting a NiO content of 4% by weight and a MoO.sub.3 content of 9% by weight, the percentages being expressed with respect to the total weight of the catalyst. The section operates as an ebullating bed having upflow of liquid and of gas. The conditions applied in the hydroconversion section C are presented in table 19.

(143) Fractionation Section (D)

(144) The effluent from the hydroconversion section C is sent into a fractionation section D composed of an atmospheric distillation, followed by a vacuum distillation, from which an unconverted vacuum residue (VR) heavy fraction boiling at a temperature of at least 540° C. is recovered, the yields with respect to the fresh feedstock and the quality of which are given in table 20.

(145) Deasphalting Section (E)

(146) The vacuum residue resulting from section D is sent into the deasphalting section E. The conditions applied in the deasphalting unit described in table 21. On conclusion of section E, a DAO fraction, which can be economically enhanced in a conversion process (hydrocracking, FCC or recycling to the hydroconversion process), and an “asphalt” fraction, which is difficult to economically enhance, are obtained. The yields and qualities of these two products are given in table 22.

(147) Section for Conversion of the DAO (F)

(148) The DAO fraction resulting from the deasphalting section E is subsequently sent to a fluidized-bed catalytic cracking unit, also known as FCC unit. This conversion unit makes it possible to transform the DAO fraction, which is a 540° C.+ cut, into lighter fractions. This thus makes it possible to increase the overall conversion of the starting feedstock (the vacuum residue (VR) originating from a Urals crude oil, the characteristics of which are presented in table 1). On the other hand, the liquid fraction resulting from the FCC unit still contains a slight unconverted 540° C.+ fraction, the yield of which is 1.2% by weight, with respect to the feedstock of the FCC, as indicated in table 26. Compared with example 4, where all the DAO was converted in a hydrocracking unit, the conversion of the DAO is in this instance not total.

(149) TABLE-US-00026 TABLE 26 Yields and qualities of the effluents resulting from the FCC unit F Unit FCC Yield Gasoline (C.sub.5-220° C.) % by weight 42.0 Yield Gas Oil (220-360° C.) % by weight 14.2 Yield Vacuum Distillate (360-540° C.) % by weight 13.8 Yield Vacuum Residue (540° C.+) % by weight 1.2
Overall Performance Qualities

(150) With this scheme according to the invention having an overall HSV=0.089 h.sup.−1 and having a moderate temperature (420/420° C.), the conversion of the heavy 540° C.+ cut is 86.1% by weight before the deasphalting stage, i.e. greater by 26.9% by weight with respect to example 7 at the same temperature level. The amount of unconverted VR recovered in example 4 is thus approximately 3 times lower. Moreover, the unconverted VR of example 8 contains lower contents of Conradson carbon and 07 asphaltenes in comparison with example 7, which makes it possible to recover a greater amount of DAO from the unconverted VR (66.8% by weight recoverable in this example, versus 54.1% by weight in example 7). Thus, this scheme according to the invention is accompanied by a lower generation of asphalt corresponding to only 3.6% by weight, with respect to the fresh starting feedstock. The DAO cut is in this instance converted in an FCC unit. With this sequential scheme according to the invention, for an overall hourly space velocity (HSV) of 0.089 h.sup.−1 and moderate temperatures (420/420° C.), the overall conversion of the heavy 540° C.+ cut in the complete scheme is 94.4% by weight, with respect to the starting heavy 540° C.+ cut, i.e. 14.4 conversion points more than in example 7. The scheme according to the invention thus makes it possible to exceed a conversion of 90% by weight, with respect to the fresh feedstock.

(151) Other solvents, such as pentane (C.sub.5), can be used in the deasphalting process instead of the butane (C.sub.4) as described here in these 8 examples. The deasphalting with C.sub.5 makes it possible to increase the DAO yields and to enhance the advantages of the invention.