Process integrating two-stage hydrocracking and a hydrotreatment process

Abstract

A process for hydrocracking hydrocarbon-containing VD feedstocks allowing the improved production of middle distillates: a) hydrocracking of feedstocks in hydrogen and at least one hydrocracking catalyst, b) gas/liquid separation of effluent originating from a) producing a liquid effluent and a gaseous effluent with hydrogen, c) comprising the gaseous effluent before recycling into hydrocracking a), d) fractionation of liquid effluent into at least one effluent of converted hydrocarbon-containing products having boiling points less than 340 C. and an unconverted liquid fraction having a boiling point greater than 340 C., e) hydrocracking unconverted liquid fraction from d), in hydrogen and a hydrocracking catalyst, f) hydrotreating effluent from e) in a mixture with a hydrocarbon-containing gas-oil liquid feedstock having at least 95% by weight of compounds boiling at a boiling point between 150 and 400 C., hydrotreating f) operating in hydrogen and with at least one hydrotreating catalyst.

Claims

1. A process for hydrocracking hydrocarbon-containing feedstock containing at least 20% by volume of compounds boiling above 340 C., said process comprising at least the following: a) hydrocracking said feedstocks, operating in the presence of hydrogen and at least one hydrocracking catalyst, at a temperature of 250 C. to 480 C. under a pressure of 2 MPa to 25 MPa, at a space velocity of 0.1 h-1 to 6 h-1 and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen/liter of hydrocarbon is 100 L/L to 2000 L/L, b) gas/liquid separation of effluent originating from a) in order to produce a liquid effluent and a gaseous effluent comprising at least hydrogen, c) compressing the gaseous effluent comprising at least hydrogen before it is recycled into at least hydrocracking a), d) fractionating the liquid effluent from b) into at least one effluent comprising converted hydrocarbon-containing products having boiling points less than 340 C. and into an unconverted liquid fraction having a boiling point greater than 340 C., e) hydrocracking of said unconverted liquid fraction originating from d), operating in the presence of hydrogen and a hydrocracking catalyst at a temperature of 250 C. to 480 C. under a pressure of 2 MPa to 25 MPa, at a space velocity of 0.1 h-1 to 6 h-1 and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen/liter of hydrocarbon is 100 L/L to 2000 L/L, f) hydrotreating effluent originating from e) in a mixture with a hydrocarbon-containing liquid feedstock comprising at least 95% by weight of compounds boiling at a boiling point of 150 C. to 400 C., said hydrotreating in f) operating in the presence of hydrogen and at least one hydrotreating catalyst, at a temperature of 200 C. to 390 C., under a pressure of 2 MPa to 16 MPa, at a space velocity of 0.2 h-1 to 5 h-1 and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen/liter of hydrocarbon is 100 L/L to 2000 L/L.

2. The process according to claim 1 in which the hydrocarbon-containing feedstock treated in said process in a) is a hydrocarbon-containing feedstock containing at least 80% by volume of compounds boiling at 370 C. to 580 C.

3. The process according to claim 1 in which the hydrocarbon-containing feedstock treated in said process in a) is a vacuum distillate (VD) that is a gas oil originating from direct distillation of crude or conversion units or distillate originating from desulfurization or hydroconversion of atmospheric residues and/or vacuum residues, deasphalted oils, or feedstocks originating from biomass or a mixture of feedstocks above.

4. The process according to claim 1 in which hydrocracking in a) operates at a temperature of 320 C. to 450 C., under a pressure of 3 MPa to 20 MPa, at a space velocity of 0.2 h-1 to 4 h-1, and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen/liter of hydrocarbon is 200 L/L to 2000 L/L.

5. The process according to claim 1 in which said hydrocarbon-containing feedstocks treated in said process are hydrotreated before being sent into hydrocracking a), said hydrotreating a) operating in the presence of hydrogen and a hydrotreating catalyst and at a temperature of 200 C. to 400 C., under a pressure of 2 MPa to 16 MPa, at a space velocity of 0.2 h-1 to 5 h-1 and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen/liter of hydrocarbon is 100 L/L to 2000 L/L.

6. The process according to claim 1 in which purging is carried out on the unconverted liquid fraction having a boiling point greater than 340 C.

7. The process according to claim 1 in which hydrocracking in e) operates at a temperature of 320 C. to 450 C., under a pressure of 3 MPa to 20 MPa, at a space velocity of 0.2 h-1 to 4 h-1, and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen/liter of hydrocarbon is 200 LL to 2000 L/L.

8. The process according to claim 1 in which the hydrocarbon-containing liquid feedstock used in e) comprises at least 95% by weight of compounds boiling at a boiling point of 150 C. to 380 C.

9. The process according to claim 1 in which hydrocarbon-containing liquid feedstock hydrotreated in f) in a mixture with effluent originating from e) are straight run gas oil, light vacuum gas oil (LVGO), light vacuum distillates, hydrocarbon-containing liquid feedstocks originating from a coking unit from a visbreaking unit, from a steam cracking unit and/or a fluid catalytic cracking unit, or a gas oil feedstock originating from biomass conversion.

10. The process according to claim 1 in which at least a part of effluent originating from hydrotreating in f) is recycled into gas/liquid separation b).

11. The process according to claim 1 in which at least a part of total effluent originating from the hydrotreating in f) is subjected to a second gas-liquid separation in order to produce a liquid effluent and a gaseous effluent comprising at least hydrogen.

12. The process according to claim 11 in which liquid effluent originating from the second separation is recycled into hydrocracking in e) and/or into hydrotreating in f).

13. The process according to claim 11 in which the gaseous effluent comprising at least hydrogen originating from the second separation is sent into compression in c).

14. The process according to claim 11 in which the gaseous effluent comprising at least hydrogen originating from the second separation stage is sent into a second compression and subsequently recycled into e) and/or into f).

15. The process according to claim 9, wherein the hydrocarbon containing liquid feedstock is light cycle oil or light gas oil from a catalytic cracking unit.

16. The process according to claim 1, wherein the hydrocarbon-containing feedstock contains at least 80% by volume of compounds boiling above 340 C.

17. A process for hydrocracking hydrocarbon-containing feedstock containing at least 20% by volume of compounds boiling above 340 C., said process comprising at least the following: a) hydrocracking said feedstocks, operating in the presence of hydrogen and at least one hydrocracking catalyst, at a temperature of 250 C. to 480 C. under a pressure of 2 MPa to 25 MPa, at a space velocity of 0.1 h-1 to 6 h-1 and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen/liter of hydrocarbon is 100 L/L to 2000 L/L, b) gas/liquid separation of effluent originating from a) in order to produce a liquid effluent and a gaseous effluent comprising at least hydrogen, c) compressing the gaseous effluent comprising at least hydrogen before it is recycled into at least hydrocracking a), d) fractionating the liquid effluent from b) into at least one effluent comprising converted hydrocarbon-containing products having boiling points less than 380 C. and into an unconverted liquid fraction having a boiling point greater than 380 C., e) hydrocracking said unconverted liquid fraction originating from d), operating in the presence of hydrogen and a hydrocracking catalyst at a temperature of 250 C. to 480 C. under a pressure of 2 MPa to 25 MPa, at a space velocity of 0.1 h-1 to 6 h-1 and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen/liter of hydrocarbon is 100 L/L to 2000 L/L, f) hydrotreating effluent originating from e) in a mixture with a hydrocarbon-containing liquid feedstock comprising at least 95% by weight of compounds boiling at a boiling point of 150 C. to 400 C., said hydrotreating in f) operating in the presence of hydrogen and at least one hydrotreating catalyst, at a temperature of 200 C. to 390 C., under a pressure of 2 MPa to 16 MPa, at a space velocity of 0.2 h-1 to 5 h-1 and at a quantity of hydrogen introduced such that the volume ratio liter of hydrogen/liter of hydrocarbon is 100 L/L to 2000 L/L.

Description

DESCRIPTION OF THE FIGURE

(1) FIG. 1 shows a particular embodiment of the invention.

(2) The hydrocarbon-containing feedstock of the VD or VGO type (1) enters a hydrocracking section A of stage a) corresponding to the first hydrocracking stage. Said section can comprise one or two hydrocracking reactors R1 and/or R2 (not shown in the FIGURE). The effluent (2) originating from stage a) is sent into a gas/liquid separator B of stage b) making it possible to isolate a gaseous flow comprising hydrogen (7). The gaseous effluent (7) is sent into a recycling compressor C, it is mixed with a makeup hydrogen flow (11) then recycled into the hydrocracking reactor via the flow (8).

(3) The liquid effluent (3) originating from the separator B supplies a fractionation column D of stage d).

(4) An effluent comprising light cuts (10), a gasoline cut (9) and a middle distillate cut (8) corresponding to gas oil and kerosene are separated in the fractionation column. An unconverted liquid fraction cut called UCO (unconverted oil) (12) is also separated then sent via the flow (4) into a second hydrocracking section E of stage e). Said hydrocracking section E comprises a hydrocracking reactor R3 (not shown in the FIGURE). Purging (13) is carried out on the flow of the unconverted liquid fraction originating from stage d).

(5) A hydrocarbon-containing liquid feedstock (12) of gas oil type is injected downstream of the hydrocracking section of the UCO E of stage e) and is treated in a hydrodesulphurization section F of stage f) in a mixture with the effluent originating from the hydrocracking section E, i.e. the hydrocracked UCO (5).

(6) The examples illustrate the invention but without however limiting its scope.

(7) Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

(8) In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

(9) The entire disclosures of all applications, patents and publications, cited herein and of corresponding French application No. 17/55.489, filed Jun. 16, 2017 are incorporated by reference herein.

EXAMPLES

Example 1a: Comparative: Dedicated Processes

(10) This example is a comparative basic example in which the processes for hydrocracking VD or VGO and for hydrodesulphurization of gas oils (GO) are implemented in two dedicated separate processes.

(11) The hydrocracking unit treats a vacuum gas oil feedstock (VGO) and the HDS gas oil unit treats a gas oil feedstock (GO) described in Table 1:

(12) TABLE-US-00001 TABLE 1 Type VGO GO Flow rate t/h 49 51 Density t/m.sup.3 0.92 0.83 TBP IP C. 300 47 TBP FP C. 552 416 S wt % 2.18 0.68 N wt ppm 1800 210
Main Operating Conditions

(13) Hydrotreating of Gas Oil

(14) The GO feedstock is injected into a preheating stage then into a hydrotreating reactor under the following conditions stated in Table 2:

(15) TABLE-US-00002 TABLE 2 Reactor HDS GO Temperature C. 336 H.sub.2 partial pressure MPa 4 CoMo on alumina Catalyst HR1246 HSV h1 1.04

(16) The catalyst used is a CoMo catalyst on alumina of the HR1246 type marketed by the company Axens.

(17) The HDS gas oil process is then composed of a heat recovery system followed by high-pressure separation including a recycling compressor and making it possible to separate on the one hand hydrogen, the sulphur- and nitrogen-containing compounds and on the other hand the desulphurized effluent supplying a steam stripper in order to separate hydrogen sulphide and naphtha.

(18) The final gas oil effluent has the following properties stated in Table 3:

(19) TABLE-US-00003 TABLE 3 Type GO Flow rate t/h 46 Density t/m.sup.3 0.82 TBP IP C. 151 TBP FP C. 450 S Wt ppm 10.00 N Wt ppm 2

(20) Two-Stage Hydrocracker

(21) The VGO feedstock is injected into a preheating stage then into a hydrotreating reactor under the following conditions stated in Table 4:

(22) TABLE-US-00004 TABLE 4 Reactor R1 Temperature C. 385 H.sub.2 partial pressure MPa 14 CoMo on alumina Catalyst HR1058 HSV h1 1.67

(23) The catalyst used is a CoMo catalyst on alumina of the HR1058 type marketed by the company Axens.

(24) The effluent from this reactor is then mixed with a hydrogen flow in order to be cooled then is injected into a second reactor called hydrocracking reactor R2 operating under the conditions in Table 5:

(25) TABLE-US-00005 TABLE 5 Reactor R2 Temperature C. 390 H.sub.2 partial pressure MPa 12.5 Metal on zeolite Catalyst HYK742 HSV h1 3

(26) The catalyst used is a metal catalyst on zeolite of the HYK742 type marketed by the company Axens.

(27) R1 and R2 constitute the first hydrocracker stage, the effluent R2 is then sent into a separation stage composed of a heat recovery system followed by high-pressure separation including a recycling compressor and making it possible to separate on the one hand hydrogen, hydrogen sulphide and ammonium hydroxide and on the other hand the effluent supplying a stripper then an atmospheric fractionation column in order to separate the concentrated flows of H.sub.2S, naphtha, kerosene, gas oil at the required specification, and an unconverted heavy flow. This unconverted heavy flow is injected into a preheating stage then into a hydrocracking reactor R3 constituting the second hydrocracking stage. This reactor R3 is implemented under the following conditions stated in Table 6:

(28) TABLE-US-00006 TABLE 6 Reactor R3 Temperature C. 345 H.sub.2 partial pressure MPa 12.5 Metal on amorphous silica-alumina Catalyst HDK766 HSV h1 3

(29) The catalyst used is a metal catalyst on amorphous silica-alumina of the HDK766 type marketed by the company Axens.

(30) The effluent from R3 is then injected into the high-pressure separation stage downstream of the first hydrocracking stage and recycled. The mass flow rate at the inlet of the reactor R3 is equal to the mass flow rate of the VGO feedstock; a purge corresponding to 2% by mass of the flow rate of the VGO feedstock is taken from the unconverted oil flow at the fractionation bottom.

(31) The distillate cut produced in the hydrocracker and recovered from the fractionation column complies with the Euro V specifications, in particular it has less than 10 ppm by weight of sulphur.

(32) The middle distillates yield of this process is 85% by mass, for an overall conversion of 98% by mass of hydrocarbons the boiling point of which is greater than 380 C.

(33) The total volume of catalyst necessary for this layout is 147 m.sup.3.

Example 1 b: Comparative: Co-Treatment of a DSV Feedstock and a Gas Oil Feedstock in a Two-Stage Hydrocracking Process

(34) This example is a comparative basic example in which the reactions for hydrocracking VD or VGO and hydrodesulphurization of gas oils (GO) are carried out in a single two-stage hydrocracking process (co-treatment of the two feedstocks)

(35) The hydrocracking unit treats a vacuum distillate feedstock (VGO) in a mixture with a gas oil feedstock (GO) identical to those used in Example 1a). The characteristics of the (VGO) and (GO) feedstocks are given in Table 1.

(36) Main Operating Conditions

(37) The mixture of the two VGO and GO feedstocks is injected into a preheating stage then into a hydrotreating reactor R1 operating under conditions identical to those used in Table 4 in Example 1a).

(38) The effluent from the reactor R1 is then mixed with a hydrogen flow in order to be cooled, then is injected into a second reactor called hydrocracking reactor R2 operating under conditions identical to those implemented in Example 1a) and described in Table 5:

(39) R1 and R2 constitute the first hydrocracker stage, the effluent from the reactor R2 is then sent into a separation stage composed of a heat recovery system followed by high-pressure separation including a recycling compressor and making it possible to separate on the one hand hydrogen, hydrogen sulphide and ammonium hydroxide and on the other hand, the effluent supplying a stripper then an atmospheric fractionation column in order to separate the concentrated flows of H.sub.2S, naphtha, kerosene, gas oil at the required specification, and an unconverted heavy flow. This unconverted heavy flow is injected into a preheating stage then into a hydrocracking reactor R3 constituting the second hydrocracking stage. This reactor R3 is implemented under the same conditions as those implemented in Example 1a) and described in Table 6.

(40) The effluent from the reactor R3 is then injected into the high-pressure separation stage downstream of the first hydrocracking stage and recycled. The mass flow rate at the inlet of the reactor R3 is equal to the mass flow rate of the VGO feedstock, a purge corresponding to 2% by mass of the flow rate of the VGO feedstock is taken from the unconverted oil flow at the fractionation bottom.

(41) The distillate cut produced in the hydrocracker and recovered from the fractionation column complies with the Euro V specifications, in particular it has less than 10 ppm by weight of sulphur.

(42) The middle distillates yield of this process is 80% by mass, for an overall conversion of 98% by mass of hydrocarbons the boiling point of which is greater than 380 C.

(43) The total volume of catalyst necessary for this layout is 110 m.sup.3.

Example 2: According to the Invention

(44) This example is a layout according to the invention in which the hydrodesulphurization of the gas oils is co-treated with the effluent from the second hydrocracking stage (thus with the hydrocracked UCO). This layout is thus composed of a single two-stage hydrocracker (there is no process dedicated to hydrodesulphurization of gas oil).

(45) The first stage of the process a) is exactly the same as the first stage according to Example 1. R1 and R2 operate on the same pure VGO or VD feedstock described in Table 1 under the same operating conditions stated in Tables 4 and 5.

(46) The effluent from the reactor R2 is then sent into a separation stage b) composed of a heat recovery system followed by high-pressure separation including a recycling compressor (stage c) and making it possible to separate on the one hand hydrogen, hydrogen sulphide and ammonium hydroxide and on the other hand the effluent supplying a stripper then an atmospheric fractionation column (stage d) in order to separate the concentrated flows of H.sub.2S, naphtha, kerosene, gas oil at the required specification, and an unconverted heavy liquid fraction (UCO) having a boiling point greater than 380 C. This unconverted heavy flow is injected into a preheating stage then into a hydrocracking reactor R3 constituting the second hydrocracking stage e). This reactor is operated under the following conditions stated in Table 7:

(47) TABLE-US-00007 TABLE 7 Reactor R3 Temperature C. 345 H.sub.2 partial pressure MPa 13 Metal on amorphous silica-alumina Catalyst HDK766 HSV h1 2.8

(48) The catalyst used is a metal catalyst on amorphous silica-alumina of the HDK766 type marketed by the company Axens.

(49) The effluent from the reactor R3 is then mixed with a GO feedstock identical to that in Example 1 described in Table 1. This GO feedstock was preheated beforehand by means known to a person skilled in the art, by thermal integration with another flow of the process. The mixture of the effluent from the reactor R3 and the GO feedstock is then injected into a hydrotreating reactor R4 (stage f) the purpose of which is the desulphurization of the GO feedstock. The operating conditions of this reactor are the following, stated in Table 8:

(50) TABLE-US-00008 TABLE 8 Reactor R4 Temperature C. 385 H.sub.2 partial pressure MPa 12.5 NiMo on alumina Catalyst HR1058 HSV h1 5.4

(51) The catalyst used is an NiMo catalyst on alumina of the HR1058 type marketed by the company Axens.

(52) The effluent from the reactor R4 (stage f) is then injected into the high-pressure separation stage b) downstream of the first hydrocracking stage a) and recycled. The mass flow rate at the inlet of the reactor R3 is equal to the mass flow rate of the VGO feedstock, a purge corresponding to 1% by mass of the flow rate of the VGO feedstock is taken from the unconverted oil flow at the fractionation bottom.

(53) The distillate cut produced, recovered from the fractionation column, conforms to the Euro V specification, in particular it has less than 10 ppm by weight of sulphur.

(54) The middle distillates yield of this process is 85% by mass, for an overall conversion of 99% by mass of hydrocarbons the boiling point of which is greater than 380 C.

(55) The total volume of catalyst necessary for this layout is 78 m.sup.3.

(56) Unexpectedly, implementing the reactor R4 of stage f) under the operating conditions stated allows, with respect to the dedicated processes of Example 1a): reducing the initial investment and consumption of catalyst in the second hydrocracking stage e), which is reflected in a reduction in the total volume of catalyst necessary for the whole process,
and with respect to co-treatment of a VD feedstock and a GO feedstock in a two-stage hydrocracking process: limiting the cracking of the feedstock of gas oil type in the hydrotreating stage which is reflected in the increase in the middle distillates yield, in addition, desulphurizing the feedstock of gas oil type, minimizing the formation of heavy polyaromatic products (HPNA), which is reflected in limiting the purge at the intake of the second hydrocracking stage and therefore increasing the conversion of the process, and in addition, desulphurizing the feedstock of gas oil type, converting the unconverted part originating from the second hydrocracking stage e), which is reflected in the reduction in the quantity of catalyst used in said hydrocracking stage e), at iso-conversion per pass of the stage constituted by the combination of the second hydrocracking stage e) and the hydrotreating stage f).

(57) The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

(58) From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.