Title of Invention

HYDROPROCESSING METHOD

Abstract 1 ABSTRACT OF THE DISCLOSURE 2 3 The instant invention comprises a hydro processing method having at least 4 two stages. The first stage employs a hydro processing catalyst v/hich may 5 contain hydrotreating catalyst, hydrocracking catalyst,.or a combination of 6 both. The second stage is limited to hydrocracking. Conversion in the 7 second stage may be improved by the addition of multiple reaction zones for S hydrocracking, with flash separation zones between the stages. Middle 9 distillate yield is thereby increased and the volume of the recycle stream is 10 reduced. This invention reduces the need for equipment which would 11 normally be required for a large recycle stream.
Full Text

1 MULTIPLE HYDROPROCESSING REACTORS
2 WITH INTERMEDIATE FLASH ZONES
3
4 FIELD OF THE INVENTION
5
6 This invention relates to hydrocracking, and more particularly to second stage
7 hydrocracking employing multiple reaction zones.
8
9 BACKGROUND OF THE INVENTION
10
11 Fuel demands are increasing worldwide. The fuels produced must meet
12 stringent standards concerned with environmental quality. The most
13 abundant feedstocks currently available are relatively heavy, such as vacuum
14 gas oil and Fischer-Tropsch streams. Hydrocracking Is used to convert heavy
15 hydrocarbon feedstocks into lighter materials which may be used to make
16 middle distillate products.
17

18 Hydrocracking is typically performed in one or more staged hydrocracking
19 units that can be independent reactors or combined into multi-staged reactors.
20 All hydrocracking processes aim to maximize yield and minimize recycle
21 volume, In most cases, however, yield maximization results in increased
22 recycle, and vice versa.
23

24 U.S. Pat. t^o. 5,705,052 discloses a process for hydro processing liquid
25 petroleum and chemical streams in a single reaction vessel containing two or
26 more hydro processing reaction stages. Both feedstock and treat gas flow
27 Go-currently in the reaction vessel. The whole partially converted hydrocarbon
28 effluent passes to the next reaction zone after being stripped of its "dissolved
29 gaseous material"..
30

31 U.S. Pat. Nos. 5,720,872 and 6,103,104 are variations of the process
32 described in U.S. Pat. No. 5,705,052. In U.S. Pat. No. 5,720,872, the major
1

1 difference is the addition of a multi-staged stripper in a single stripper vessel.
2 U.S. Pat. No. 6,103,104 employs the concept of Interfaed quench between the
3 hydro processing stages.
4

5 U.S. Pat. No. 6,017,443 discloses a process for catalytic hydroprocessing, in
6 which a feedstock is introduced at the top of the lower reaction zone for
7 downward flow through and reaction with the catalyst therein. In one
8 embodiment, a partially reacted liquid efRuent is pumped from the lower
9 reaction zone to the top of the upper reaction zone for downward flow through

10 and reaction with the catalyst in that zone. The recycle is not fractionated into
11 product and unconverted material prior to recycling, however.
12

13 U.S. Pat. No. 4,082,647 discloses a hydrocracking process with two reactors
14 operating in parallel rather than in series. Two different feedstocks may be
15 hydrocracked to maximize distillate production. The second feed Is mixed
16 with the vaporous phase from separation of effluent from the conversion of the
17 first feedstock.
18

19 U.S. Pat. No. 4,197,184 discloses a conventional multiple-stage process for
20 hydrorefining and hydrocracking a heavy hydrocarbonaceous charge stock. In
21 the process, hydrocracked effluent is admixed with hydnsrefined effluent and
22 the combination separated into a hydrogen rich vaporous stream and normally
23 liquid material. The cooled vapor stream is then used as a source of
24 hydrogen and as a quench fluid for both the hydrorefining reaction zone and
25 the hydrocracking reaction zone.
26
27 U.S. Pat. No. 6,106,695 discloses a process having more than one
23 hydrocracking reaction zone which contains hydrocracking catalyst, wherein
29 the catalyst is rejuvenated or reactivated while the process unit remains
30 on-stream by the periodic exposure of partially spent catalyst to hot recycle
31 gas containing hydrogen. The reactors in this process operate in parallel
32 rather than in series.

1 SUMMARY OF THE INVENTION
2
3 The instant invention comprises a hydroprocessing method having at least
4 two stages. The first stage employs a hydroprocessing catalyst which may
5 contain hydrotreating catalyst, hydrocracking catalyst,, or a combination of
6 both. The second stage employs a series of fixed bed reaction zones, with
7 feed and hydrogen in co-current flow, with Inter-bed removal of gas and
8 products. Gas and product removal occur in a flash separation zone in which
9 hydrogen preferably enters countercurrently.
10

11 The process of the instant invention maximizes middle distillate yield while
12 minimizing the volume of recycle. Per-pass conversion is defined as fresh
13 feed converted in a stage divided by total feed to a stage. The per-pass
14 conversion rate in each reactor vessel remains low, 40% or less, while the
15 overall conversion rate is 60% or greater.
16

17 The process of this invention provides economy in equipment employed.
18 Single bed reactors, which are smaller, have lower capacity, and are easier to
19 maintain than multiple bed reactors, may be used. The use of small, single
20 bed reactors provides fiexibility in second stage operation. They are of simple
21 design and do not require quench gases or liquids. This promotes economic
22 operation.
23

24 The hydroprocessing method of the instant invention, which has at least two
25 reaction stages, comprises the following steps:
26
27 (a) passing a hydrocarbon feed into a first reaction stage, which is
28 maintained at hydroprocessing conditions, where it is contacted with a
29 catalyst in a fixed bed and at least a portion of the feed is converted;
30 (b) combining the effluent of step (a) with product material from the second
31 reactor stage and passing the combined stream to a separation zone;

1 (c) separating the stream of step (b) into an unconverted liquid effluent and
2 at least one converted stream comprising products having a boiling point
3 below that of the feed;
4
5 (d) passing the unconverted liquid effluent from step (c) to a second
6 reaction stage, said stage comprising a plurality of reaction zones,
7 wherein each zone is maintained at hydrocracking conditions and
8 separation occurs between each zone;
9
10 (e) contacting the feed In the first reaction zone of step (d) with a catalyst In
11 a fixed bed, thereby converting at least a portion of the feed;
12
13 (f) separating the effluent of step (e) into an unconverted liquid effluent, and
14 a hydrogen-rich converted stream;
15
16 (g) recycling the hydrogen-rich converted stream of step (f) to combine with
17 the effluent of step (a);
18 (h) passing the unconverted liquid effluent from step (f) to a second reaction
19 zone of the second stage, the zone being maintained at hydrocracking
20 conditions;
21
22 (i) contacting the feed in the second reaction zone of step (h) with a
23 catalyst in a fixed bed, thereby converting at least a portion of the feed;
24
25 G) fractionating the effluent of step (i) to produce gas, naphtha, and one or
26 more middle distillate product streams, unconverted material being
27 recycled to step (d).

1 BRIEF DESCRIPTION OF THE DRAWINGS
2
3 Figure 1 illustrates a schematic flow diagram of the instant invention. It is a
4 schematic of a two-stage hydrocracker. The second stage possesses at least
5 two reaction zones.
6

7 Figure 2 illustrates the pilot plant simulations of two second-stage reaction
8 zones in series.
9
10 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
11
12 The instant invention is directed to a h yd reprocessing method which Is
13 particularly useful in the second stage hydrocracking step of integrated
14 processes such as those disclosed In U.S. Pat No. 6,179,995 (09/227,235),
15 an integrated process for h yd reconverting a residuum feedstock.
16

17 Figure 1 illustrates a hydrocracking process in which there are at least two
18 fixed bed reaction zones in series. Following each fixed bed reaction zone
19 (prior to the last one in the series) is an intermediate flash zone for separation
20 of converted materials from unconverted materials. In the fixed bed reaction
21 zones, hydrogen is Injected preferably in a co-current direction to the fixed
22 bed effluent.
23

24 In Figure 1, the feedstock stream 1 enters the first hydroprocessing stage 3
25 (which comprises at least one fixed bed reactor), along with hydrogen stream
26 2. Streams 1 and 2 enter the top of the reactor and flow downward,
27 contacting the fixed catalyst bed 4. The effluent 5 combines with product
28 stream 25 to form stream 6. Stream 6 enters the fractionator 7, where it is
29 separated into product streams, which are further discussed below. Product
30 streams include gas 9, naphtha 10, kerosene 11, and dieset 12. The
31 unconverted material, stream 13 boils above typically 700°F. It passes to the
32 first reaction zone of stage 2, reactor 15. Stream 13 and 14 (the hydrogen

33 stream) flow downward through fixed hydrocracking catalyst bed 16. The
34 effluent of reactor 15, stream 17 passes to separation zone 18. Product,
35 which boils below 700°F, is removed in stream 19. Stream 20, which contains
36 unconverted material, enters the second reaction zone of stage 2, reactor 22,
37 along with stream 21, which comphses hydrogen. Streams 20 and 21 flow
38 downwardly through fixed hydrocracking catalyst bed 23. Stream 24, the
39 effluent of reactor 22, combines with stream 19 to form stream 25.
8
9 The per-pass conversions in both reactors 15 and 22 are typically between
10 30% and 40%.
11
12 Feeds
13
14 A wide variety of hydrocarbon feeds may be used in the Instant Invention.
15 Typical feedstocks include any heavy or synthetic oil fraction or process
16 stream having a boiling point above 392'F (200°C). Such feedstocks include
17 vacuum gas oils, demetallized oils, deasphalted oil, Fischer-Tropsch streams,
18 FCC and coker distillate streams, heavy crude fractions, etc. Typical
19 feedstocks contain from 100-5000 ppm nitrogen and from 0.2-5 wt. % sulfur.
20
21 Products
22
23 The hydrocracking process of this invention is especially useful in the
24 production of middle distillate fractions boiling in the range of about 250-700°F
25 {121-371'C). A middle distillate fraction is defined as having a boiling range
26 from about 250 to 7O0'F, The term "middle distillate" Includes the diesel, jet
27 fuel and kerosene boiling range fractions. The kerosene or jet fuel boiling
28 point range refers to the range between 280 and 525°F (138-274°). The term
29 - "diesel boiling range" refers to hydrocarbons boiling in the range from 250 to
30 700°F (121-371°C). Gasoline or naphtha normally boils in the range below
31 400° (204^0). Boiling ranges of various product fractions recovered in any

32 particular refinery will vary with such factors as the characteristics of the crude
33 oil source, local refinery markets and product prices.
3
4 Conditions
5
6 Hydreprocessing conditions is a general term which refers primarily In this
7 application to hydrocraeking or hydrotreating, preferably hydrocracking.
8 Hydrotreating conditions include a reaction temperature between 400°F-900*F
9 {204°C-482°C), preferably 650°F-850°F (343°C-454°C); a pressure between

10 500 to 5000 psig (pounds per square inch gauge) (3.5-34.6 MPa), preferably
11 1000 to 3000 psig (7.0-20.8 MPa); a feed rate (LHSV) of 0.5 hr'^ to 20 hr'
12 (v/v); and overall hydrogen consumption 300 to 2000 scf per barrel of liquid
13 hydrocarbon feed (53.4-356 m^/m^ feed).
14

15 Typical hydrocracking conditions include a reaction temperature of from
16 400°F-950'F (2Q4°C-510°C), preferably 650^F-850°F (343°C-454°C).
17 Reaction pressure ranges from 500 to 5000 psig (3.5-34.5 MPa), preferably
18 1500-3500 psig (10,4-24.2 MPa). LHSV ranges from 0.1 to 15 hr^ (v/v),
19 preferably 0.25-2.5 hf\ Hydrogen consumption ranges from 500 to 2500 scf
20 per barrel of liquid hydrocarbon feed (89.1 -445m^ H2/m^ feed).
21
22 Catalyst
23
24 A hyd reprocessing zone may contain only one catalyst, or several catalysts in
25 combination.
26

27 The hydrocracking catalyst generally comprises a cracking component, a
28 hydrogenation component and a binder. Such catalysts are well Known in the
29 art. The cracking component may include an amorphous silica/alumina phase
30 and/or a zeolite, such as a Y-type or USY zeolite. Catalysts having high
31 cracking activity often employ REX, REV and USY zeolites. The binder is

32 generally silica or alumina. The hydrogenatlon component will be a Group Vl.
33 Group VII, or Group VIII metal or oxides or sulfides thereof, preferably one or
34 more of molybdenum, tungsten, cobalt, or nickel, or the sulfides or oxides
35 thereof. If present in the catalyst, these hydrogenatlon components generally
36 make up from about 5% to about 40% by weight of the catalyst. Alternatively,
37 noble metals, especially platinum and/or palladium, may be present as the
38 hydrogenatlon component, either alone or in combination with the base metal
39 hydrogenatlon components molybdenum, tungsten, cobalt, or nickel. If
40 present, the platinum group metals will generally make up from about 0.1 % to

10 about 2% by weight of the catalyst. If noble metals are employed, poisoning
11 is avoided due to the use of small reactors and the constant Influx of
12 hydrogen.
13

14 Hydrotreating catalyst, if used, will typically be a composite of a Group VI
15 metal or compound thereof, and a Group VIII metal or compound thereof
16 supported on a porous refractory base such as alumina. Examples of
17 hydrotreating catalysts are alumina supported cobalt-molybdenum, nickel
18 sulfide, nickel-tungsten, cobalt-tungsten and nicket-molybdenum. Typically,
19 such hydrotreating catalysts are presulfided.
20
21 EXAMPLES
22
23 Figure 1 is a schematic of this invention. The effluent of a first-stage
24 hydro processor passes to a fractionator. The unconverted portion of the first
25 stage hydro processor passes to a second-stage hydrocracker. The
26 second-stage hydrocracker comprises multiple reaction zones which are
27 connected in series, with interstage separation zones. Unconverted material
28 removed from each separation zone is passed to the next reaction zone and
29 product is fractionated Into middle distillate products and a recycle stream.
30

31 Figure 2 represents a pilot plant simulation of this invention. The feed to the
32 second-stage hydrocracker is a hydrotreated Middle East vacuum gas oil.

33 Fresh feed (represented by 100 units) joins with recycle (represented as
34 67 units) and passes to reaction zone 1. 40% per-pass conversion (67/16?)
35 occurs, and products are removed by fractionation. Bottoms (33 units) are
36 passed to reaction zone 1, where it is combined with recycle from reaction
37 zone 2 (67 units) prior to entry into the reaction zone. 33% (33/100) of the
38 material is converted and fractionated as products. Per-pass
39 conversion = fresh feed converted in a stage/total feed to a stage.
8
9 The Table below presents the conditions employed in this example. The
10 recycle cut point is 700'F. The hydrogen partial pressure is 2100 psia. Three
11 different scenarios are depicted. In the first case, a standard second-stage
12 hydrocracking mode Is employed, rather than the mode of this invention. The
13 liquid hourly space velocity (LHSV) is 1 hr"'. The per-pass conversion is 6Q%.
14 The catalyst employed is an amorphous, base metal catalyst. In the second
15 case, a zeolite loaded with noble metal is employed as the catalyst and the
16 LHSV is 2 f)r'\ A standard second-stage mode Is also employed, with 60%
17 per-pass conversion.
18

19 The third case depicts a second-stage hydrocracker with more than one
20 reaction zone, as in the Instant invention. The same noble metal/zeolite
21 catalyst as in the second case is employed. In the third case, the individual
22 per-pass conversions for each reaction zone are 40% and 33%, respectively,
23 while the overall per-pass conversion Is 60%. The LHSV is 2 hr24

25 As the Table below illustrates, second-stage distillate yield is greatest when
26 the third case is employed.
27

1
2


COMPARISOI^ OF SECOND-STAGE ISOCRACKING YIELDS
HDT Middle East VGO, 700T Recycle Cut Point, -2100 psia Ha
Case 1 2 3
Catalyst Amorphous NMZ (Noble NMZ (Noble metal
Base Metal metal zeolite) zeolite)
Conditions
LHSV, 1/hr 1.0 2.0 2.0
PPC, % 60 60 40'
Mode Standard Standard Two-stages with
intermediate
separation
Yields
04- 4.4 3.4 2.5
C5-250°F. LV% 22.6 22.0 16.4
250-550='F 51.3 60.3 56.4
550^F-700°F 34.0 26.9 35.1
250-7QQ°F 85.3 87.2 91.5
'Recycle liquid rate of 60% PPC.

1 WHAT IS CLAIMED IS:
2
3 1. The hydroprocessing method of the instant invention, which has at least
4 two reaction stages, comprises the following steps:
5
6 (a) passing a hydrocarbon feed into a first reaction stage, which is
7 maintained at hydroprocessing conditions, where it is contacted
8 with a catalyst in a fixed bed and at least a portion of the feed is
9 converted;
10
11 (b) combining the effluent of step (a) with product material from the
12 second reactor stage and passing the combined stream to a
13 separation zone;
14
15 (c) separating the stream of step (b) into an unconverted liquid effluent
16 and at least one converted stream comprising products having a
17 boiling point below that of the feed;
18
19 (d) passing the unconverted liquid effluent from step (c) to a second
20 reaction stage, said stage comprising a plurality of reaction zones,
21 wherein each zone is maintained at hydrocracking conditions and
22 separation occurs between each zone;
23
24 (e) contacting the feed in the first reaction zone of step (d) with a
25 catalyst in a fixed bed, thereby converting at least a portion of the
26 feed;
27
28 (f) separating the effluent of step (e) into an unconverted liquid
29 effluent, and a hydrogen-rich converted stream;
30
31 (g) recycling the hydrogen-rich converted stream of step (f) to combine
32 with the effluent of step (a);

1 (h) passing the unconverted liquid effluent from step (f) to a second
2 reaction zone of the second stage, the zone being maintained at
3 hydrocracl 4
5 (i) contacting the feed in the second reaction zone of step (h) with a
6 catalyst in a fixed bed, thereby converting at least a portion of the
7 feed;
8
9 0) fractionating the effluent of step (i) to produce gas, naphtha, and
10 one or more middle distillate product streams, unconverted
11 material being recycled to step (d).
12
13 2. The process of claim 1(d), wherein the inlet temperature of each reaction
14 zone in the second stage subsequent to the first reaction zone is lower
15 than the previous one and the outlet temperature of each reaction zone
16 subsequent to the first reaction zone is lower than the previous one.
1?
18 3. The process of claim 2, wherein the average reaction temperature of
19 each reaction zone subsequent to the first reaction zone is at least 50°F
20 lower than the average reaction temperature of the previous one.
21
22 4. The process of claim 1, wherein the catalyst of each reaction zone of the
23 second stage of step (d)-is a hydrocracking catalyst,
24
25 5. The process of claim 4, wherein each of the reaction zones of the
26 second stage is operated under hydrocracking conditions including
27 temperatures in the range from about 400-950°F (204-510°C), reaction
28 pressure in the range from 500 through 5000 psig (3.5-34.5 MPa), LHSV
29 _ of 0.1 to 15 hr"^'and hydrogen consumption of 500 through 2500 scf per
30 barrel of liquid hydrocarbon feed (89.1-445 m^ H2 feed).

1 6. The process of claim 5, wherein more preferred hydrocracking
2 conditions include a temperature range from 650-850T {343°C-454°Cl
3 reaction pressure from 1500 psig through 3500 psig {10.4-24.2 MPa)
4 and LHSV 0.25 through 2.5 hr\and hydrogen consumption of 500
5 through 2500 scf per barrel of liquid hydrocarborv feed (89.V445m^ H^
6 feed).
7
8 7. The process of claim 1, wherein the unconverted effluent comprises
9 hydrocarbons which boil above 700°F.
10
11 8. The process of claim 1, wherein the converted stream comprises
12 hydrocarbons boiling below 70Q°F.
13 9. The process of claim 1, wherein the overall hydrocarbon conversion is at
14 least 60% and the hydrocarbon conversion for each reaction zone is in
15 the range from 20% to 40%.
16
17 10. The process of claim 1, wherein the converted stream from each
18 reaction zone is continuously combined and fractionated into at least
19 one fuel product.
20
21 11. The process of claim 10, wherein the preferred fuel product is diesel.
22
23 12. The process of claim 10, wherein the preferred fuel product is jet fuel.
24
25 13. The process of claim 10, wherein the preferred fuel product is naphtha.
26
27 14. The process of claim 1, wherein the feed is subjected to a preliminary
28 hydrotreating step.

15. The hydroprocessing method ot" the instant invention substantially as
herein described with reference to the accompanying drawings.


Documents:

0782-mas-2002 abstract.pdf

0782-mas-2002 claims.pdf

0782-mas-2002 correspondences others.pdf

0782-mas-2002 correspondences po.pdf

0782-mas-2002 descripition(completed).pdf

0782-mas-2002 drawings.pdf

0782-mas-2002 form-1.pdf

0782-mas-2002 form-18.pdf

0782-mas-2002 form-3.pdf

782-MAS-2002 AMANDED CLAIMS 05-10-2009.pdf

782-MAS-2002 AMANDED PAGE OF SPECIFICATION 05-10-2009.pdf

782-MAS-2002 FORM-3 05-10-2009.pdf

782-MAS-2002 OTHER DOCUMENT 05-10-2009.pdf

782-MAS-2002 OTHER PATENT DOCUMENT 05-10-2009.pdf

782-MAS-2002 POWER OF ATTORNEY 05-10-2009.pdf


Patent Number 238210
Indian Patent Application Number 782/MAS/2002
PG Journal Number 6/2010
Publication Date 05-Feb-2010
Grant Date 25-Jan-2010
Date of Filing 23-Oct-2002
Name of Patentee CHEVRON USA INC
Applicant Address 2613 CAMINO RAMON, SAN RAMON, CALIFORNIA 94583-4289.
Inventors:
# Inventor's Name Inventor's Address
1 ARTHUR J.DAHLBERG 695 EARL COUNT, BENICIAL, CALIFORNIA 94510.
2 JEROME F.MAYER 27 WOODLEAF COURT,NOVATO, CALIFORNIA 94945.
PCT International Classification Number C10G65/12
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/001,737 2001-10-25 U.S.A.