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.

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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