CA1237692A - Dual riser fluid catalytic cracking process - Google Patents

Dual riser fluid catalytic cracking process

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Publication number
CA1237692A
CA1237692A CA000467099A CA467099A CA1237692A CA 1237692 A CA1237692 A CA 1237692A CA 000467099 A CA000467099 A CA 000467099A CA 467099 A CA467099 A CA 467099A CA 1237692 A CA1237692 A CA 1237692A
Authority
CA
Canada
Prior art keywords
catalyst
feedstock
riser
contacting
process according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000467099A
Other languages
French (fr)
Inventor
James F. Crocoll
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shell Canada Ltd
Original Assignee
Shell Canada Ltd
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Filing date
Publication date
Application filed by Shell Canada Ltd filed Critical Shell Canada Ltd
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Publication of CA1237692A publication Critical patent/CA1237692A/en
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Classifications

    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10GCRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G51/00Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more cracking processes only
    • C10G51/02Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more cracking processes only plural serial stages only
    • C10G51/026Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more cracking processes only plural serial stages only only catalytic cracking steps
    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10GCRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G11/00Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
    • C10G11/14Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid catalysts
    • C10G11/18Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid catalysts according to the "fluidised-bed" technique

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  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

Abstract

A B S T R A C T

DUAL RISER FLUID CATALYTIC CRACKING PROCESS

An improved fluid catalytic cracking process for achieving high conversions of low quality feedstocks (containing metal contaminants, basic nitrogen and/or coke precursors) at relatively low severities, by passing the feedstock in series through a dual riser reactor system having a common catalyst stripper and regenerator, in contact with freshly regenerated catalyst which is passed in parallel from the regenerator through each of the riser reactors.

Description

7~3~

DULL RISER Fluid CATALYTIC CRACKING PPDCESS

This invention relates to a dual riser fluid catalytic cracking pry ens wherein a low quality feed stock is passed through the risers in series; the fistic is in contact with freshly regenerated catalyst which is passed through the risers in parallel.
Catalytic cracking is the major molecular weigh reduction process employed in petroleum refix no for manufacturing gasoline as fuels. Business incentives require the processing of heavier, low-quality feed stocks, fewer output of residual products and increased energy efficiencies while meeting more stringent environmental constraints. Current catalysts require high temperature and short contact time riser reactors to obtain the full benefits of the process, i.e., highest selectivity to gasoline at highest conversion yields. These catalysts require high temperature regeneration Tao combustion). This approach also allows for catalysts with greater metals tolerance, octane enhancement and Six capture.
In the catalytic cracking of low quality hydrocarbon feed stocks, metal contaminants such as nickel, vanadium and iron are deposited on the catalyst and reduce its effectiveness in converting the feed stock to lower boiling components such as gasoline. One way of at least partially overcoming these adverse effects is by treating the catalyst with agents which reduce the anility of contaminants on the catalyst to adversely affect the Z5 cracking process. For example, in US. 4.326,990 selected treating agents are added to the feed stock; in the reactor these agents are deposited on the catalyst.
The effectiveness of a cracking catalyst is also reduced by temporary catalyst poisons such as basic nitrogen components and high boiling coke precursors, which reduce the ability of the catalyst to achieve high conversion of the feed without excessive cracking to undesirable light hydrocarbons.
In catalytic cracking many different reactor configurations have been proposed, all claiming to haze certain advantages. For example, in US. Patent 4,090,949 a aural riser reactor catalytic cracking system is disclosed, having a common catalyst regenerator supplying freshly regenerated catalyst to each riser, whilst fresh gas oil feed is contacted with freshly regenerated catalyst in the first riser and light C2-C5 olefins are contacted with freshly regenerated catalyst in the second riser. In another dual riser catalytic cracking system, as disclosed in US. Patent 3,748,251 charge stock is passed into a reaction zone together with a catalyst composition comprising two cracking components, part of which is ZSM-5, hydrocarbons are withdrawn from the reaction zone, unrequited hydrocarbon charge is separated and introduced into a second reaction zone together with said catalyst.
It is an object of this invention to remove from the feed stock essentially all of the temporary catalyst poisons, such as basic nitrogen constituents and coke precursors, an* metal contamiI~ults at relatively low conversions, e.g., 15 to 25~ in the first reactor, thereby requiring low severity, i.e., lower catalyst/oil ratios.
It is another object of the invention to catalytically crack the total product from the first reactor to a high conversion at low severity over freshly regenerated catalyst It is a further object of the invention that the total severity required for these two separate subsequent steps of cracking will be significantly lower than that required if the same total conversion were achieved in a single step.
It is a still further object of the invention to use a common catalyst inventory to remove metal contaminants comprising nickel and/or vanadium and temporary catalyst poisons and to achieve a high conversion of low quality feedstocksO
mix invention relates to an improved fluid catalytic cracking process for low quality hydrocarbon feed stocks, said ~23'7g~

process having a dual riser reactor system with a gammon catalyst stripper and regenerator, which comprises passing said feed stock into a first riser reactor zones an contacting said feed stock with freshly regenerated fluid cracking catalyst under relatively low severity reaction conditions suitable for relatively low conversion of feed stocks to lower boiling components while simultaneously reducing metal con tam mints and temporary catalyst poisons contained therein; separating first riser reaction products from catalyst in a first separation zone and passing a 1.0 mixture of relatively clean unconverted feed stock and reaction products from said separation zone into a second riser reactor zone, and contacting the mixture with freshly regenerated fluid cracking catalyst under relatively low severity reaction conditions suitable for relatively high conversion of feed stocks to lower boiling components; separating second riser reaction products from catalyst in a second separation zone; passing partially deactivated catalyst, containing metal contaminants, coke and unrequited hydrocarbons, from both separation zones to a catalyst stripper and contacting said catalyst with steam under conditions to remove a substantial portion of said unrequited and/or adsorbed hydrocarbons passing catalyst from the stripper to a regenerator and contacting said catalyst with air under reaction conditions suitable to ccmbust coke and unconverted hydrocarbons; separating combustion products from regenerated catalyst as flue gas; circulating freshly regenerated catalyst to both risers for contacting fresh feed stock and said mixture of unconverted feed stock and reaction products respectively; and recovering cracked products from the second separation zone.
The process according to the invention can be suitably applied to few quality hydrocarbon feed stocks containing metal contaminants comprising nickel and/or vanadium in amounts from about 1 to 100 parts per million by weight (ppmw). It can also be suitably applied to hydrocarbon feed stocks containing from about 300 to 8000 ppmw of basic nitrogen. Furthermore, the process can ,3 be suitably applied to hydrocarbon feed stocks containing from about 0.5 to 10 ow of coke precursors, determined as Rams bottom Carbon Residue. The process according to the invention is suitably carried out using well-kncwn catalysts, such as commercially available cracking catalysts and, in particular X or Y type zealots contained in a silica-alumina matrix.
The process according to the present invention, which is carried out in a two reactor-one regenerator system with the feed in series flow and the catalyst in parallel flow, is illustrated in Fig. 1.
In the dual riser catalytic cracking process shown in Fig. 1, the system includes primarily a catalyst regeneration zone 2, a catalyst stripper zone 4, a first catalyst separation zone 6, and a second catalyst separation zone 8.
Fresh feed stock is introduced into the system via line 10, where it is contacted with freshly regenerated catalyst from regenerator 2 via line 12. The feed stock and catalyst are passed under suitable reaction conditions upwardly through the first riser line 14) wherein the feed stock is partially converted to lower boiling components. The mixture of unconverted feed, conversion products and catalyst is then passed into a first separation zone 6, wherein catalyst and gaseous hydrocarbons are separated. An optional emkcdiment of the invention is to add prestripping steam to separation zone 6 via line 50. The separated catalyst, which is partially deactivated, is passed via line 16 to a riser pot 18, where it it contacted by steam introduced via line 30 an lifted via line 32 to catalyst stripper 4.
The gaseous hydrocarbons from separation zone 6 are passed via line 20 to the second riser (line 24) where they are contacted witch freshly regenerated catalyst from regenerator 2 via line 22 and passed under suitable reaction conditions upwardly through said second riser, wherein a substantial portion of the unconverted feed stock from catalyst separation zone 6 is converted to lower boiling components. me mixture of unconverted feed, 7~?2 conversion products and catalyst is then passed into a second separation zone 8, wherein catalyst and gaseous hydrocarbons are separated. An optional embodiment of the invention is to add prestripping steam to separation zone 8 via line 51. me separated catalyst, which is partially deactivated, is passed via line 26 to a riser pot 18, where it is combined with catalyst from separation zone 6, and is contacted by steam introduced via line 30 and lifted via line 32 to catalyst stripper 4.
The gaseous hydrocarbons from catalyst separation zone 8 are passed via line 40 to a fractionator where suitable cracked products are recovered.
The hydrocarbons and gases stripped from the catalyst in stripper 4 are passed via line 42 to the same or another fractionator for separation of water and recovery of products.
The stripped catalyst from stripper 4 is passed via line 28 to a regeneration zone 2, where it is contacted with air introduced via line 38. The partially deactived catalyst is regenerated under conditions suitable to remove coke and basic nitrogen compounds. Flue gases from the regeneration zone are vented via line 44. Freshly regenerated catalyst is circulated to the first and the second riser via lines 12 and 22, respectively, and the process is continued.
EXIT
-This example illustrates the benefits to be realized by removing temporary catalyst poisons from low quality catalytic cracking feed stocks.
TWO feedstccks, A (light flashed distillate) and B
(commercial FCCU feed), were deresined in the laboratory.
Properties of the total and deresined feed stocks are shown in Table lo Feed stock A was a fairly high quality, glean light flashed distillate and was included for comparison. Feed stock B
was a low quality feed, such as those suitable for the process of the invention, which contained a significant amount of basic nitrogen compounds.

37~

me deresining step consists of mixing the feed stocks with isooctane and passing -the mixture over attapulgas clay. Other suitable clays for this purpose include Elders Earth and Florex-S. m e twill resins, including the basic nitrogen compounds, are adsorbed on the clay.
Feed stocks A and B, both before and after deresining, were then tested in a micro activity test (MAT) unit.
The MAT used in these studies and the operating procedure were similar to those described in ASTM D 3907-80. Briefly about 5.0 grams of catalyst are contained in a small diameter reactor (ASTM specifies 15.6 em I.D.). The feed is passed over the catalyst for about 60 seconds. Immediately after the oil addition, nitrogen is introduced to strip the catalyst Both a liquid and a gas are recovered as products. These are conveniently analyzed by conventional chromatographic equipment.
The results of the micro activity tests are plotted in Figs.
AWOKE (feed stock A) and AWOKE (feed stock B). In all graphs, the straight lines relate to experiments carried out with total feed and the dotted lines relate to experiments carried out with deresined feed stock.
In Figures PA and PA the conversions of total feed and deresined feed stock, respectively into 232 C material, expressed as wow of 232 C material are plotted (on the horizontal axis) against the coke production in ow. In Figures 2B and 3B the conversions (as expressed for Figures PA and 3 A) are plotted against the yield of the C5-232 C fraction. Finally, in Figures 2C and 3C, respectively, the weight hourly space velocities are plotted (on the horizontal axis) against the conversions of total feed and deresined feed stock, respectively, as expressed herein before. It will be clear from the Figures AWOKE in comparison with Figures AWOKE that the imprsve~ent in cracking characteristics (less refractory, more gasoline and less coke) fulling deresining is significantly greater for Feed stock B than for Feed stock A.
* Trade Mark I

Cracking Feed stock B to a low conversion in a first riser reactor will achieve essentially the same benefits as the deresining treatment. The total product from us low conversion first reactor can then be easily cracked at GUY severity to a high conversion in a second riser reactor.

I

__ Feeds Feeds~cck A Feed stock B
-Total Deresined Total Deresined Feed if Feed Oil ) APT Gravity 24.7 25.6 22.7 24.7 Sol Weight 320 - 331 Basic No, OWE 0.00 0.10 0.00 Kowtows OW
Alikeness 22.4 23.4 10.1 11.2 Cycle Alikeness 34.6 36.2 40.1 Moo Aromatics 16.9 16.6 18.1 17.9 Do Aromatics 19.2 23.4 23.7 Try Aromatics 6.2 10.7 6.9 Tory Aromatics 0.1 OWE 0.5 0.2 Basic No Nuclei 0.2 0.0 1.0 COO

00.0 100.0 100.0 100. 0 I 4.3 ow Resins Removed
(2) 9.8 ow Resins Removed

Claims (6)

C L A I M S
1. An improved fluid catalytic cracking process for low quality hydrocarbon feedstocks, said process having a dual riser reactor system with a common catalyst stripper and regenerator, which comprises passing said feedstock into a first riser reactor zone and contacting said feedstock with freshly regenerated fluid cracking catalyst under relatively low severity reaction conditions suitable for relatively low conversion of feedstocks to lower boiling components while simultaneously reducing metal contaminants and temporary catalyst poisons contained therein;
separating first riser reaction products from catalyst in a first separation zone and passing a mixture of relatively clean un-converted feedstock and reaction products from said separation zone into a second riser reactor zone and contacting the mixture with freshly regenerated fluid cracking catalyst under relatively low severity reaction conditions suitable for relatively high conversion of feedstocks to lower boiling components; separating second riser reaction products from catalyst in a second separation zone; passing partially deactivated catalyst, containing metal contaminants, coke and unreacted hydrocarbons from both separation zones to a catalyst stripper and contacting said catalyst with stem under conditions to remove a substantial portion of said unreacted and/or adsorbed hydrocarbons; passing catalyst from the stripper to a regenerator and contacting said catalyst with air under reaction conditions suitable to combust coke and unconverted hydrocarbons; separating combustion products from regenerated catalyst as flue gas; circulating freshly regenerated catalyst to both risers for contacting fresh feedstock and said mixture of unconverted feedstock and reaction products, respectively; and recovering cracked products from the second separation zone.
2. A process according to claim 1, wherein the feedstock contains from about 1 to 100 ppmw of metal contaminants comprising nickel and/or vanadium.
3. A process according to claim 1, wherein the feedstock contains from about 300 to 8000 ppmw of basic nitrogen.
4. A process according to claim 1, wherein the feedstock contains from about 0.5 to 10 %w of coke precursors determined as Ramsbottom Carbon Residue.
5. A process according to claim 1, wherein the conversion in the first riser is in the range of about 15 to 25 %w based on the feedstock.
6. A process according to claim 1, wherein the conversion after the second riser is between about 55 and 80 %w, based on the fresh feedstock.
CA000467099A 1983-11-22 1984-11-06 Dual riser fluid catalytic cracking process Expired CA1237692A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US55446983A 1983-11-22 1983-11-22
US554,469 1983-11-22

Publications (1)

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CA1237692A true CA1237692A (en) 1988-06-07

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EP (1) EP0142900B1 (en)
JP (1) JPS60144388A (en)
CA (1) CA1237692A (en)
DE (1) DE3479427D1 (en)
NL (1) NL8403539A (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1190019A1 (en) * 2000-02-16 2002-03-27 Indian Oil Corporation Limited A multi stage selective catalytic cracking process and a system for producing high yield of middle distillate products from heavy hydrocarbon feedstocks
US20080011644A1 (en) 2006-07-13 2008-01-17 Dean Christopher F Ancillary cracking of heavy oils in conjuction with FCC unit operations
US8124822B2 (en) 2009-03-04 2012-02-28 Uop Llc Process for preventing metal catalyzed coking
US8124020B2 (en) 2009-03-04 2012-02-28 Uop Llc Apparatus for preventing metal catalyzed coking
US9458394B2 (en) 2011-07-27 2016-10-04 Saudi Arabian Oil Company Fluidized catalytic cracking of paraffinic naphtha in a downflow reactor
EP3106504B1 (en) 2015-06-19 2020-02-05 Reliance Industries Limited Process for propylene and lpg recovery in fcc fuel gas
US9896627B2 (en) 2015-10-14 2018-02-20 Saudi Arabian Oil Company Processes and systems for fluidized catalytic cracking
US20230407187A1 (en) * 2022-06-17 2023-12-21 Kellogg Brown & Root Llc Converting Motor Fuels Range Distillates to Light Olefins in a Multiple Riser Fluid Catalytic Cracking (FCC) Unit

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3751359A (en) * 1971-09-27 1973-08-07 Texaco Inc Conversion of hydrocarbons
US3894933A (en) * 1974-04-02 1975-07-15 Mobil Oil Corp Method for producing light fuel oil
US4090949A (en) * 1974-07-31 1978-05-23 Mobil Oil Corportion Upgrading of olefinic gasoline with hydrogen contributors
US4073717A (en) * 1976-01-26 1978-02-14 Aliev Vagab Safarovich Process for producing gasoline
FR2378847A1 (en) * 1977-01-28 1978-08-25 Melik Akhnazarov Talyat Two=stage catalytic hydrocarbon cracking - with co-current and counter current reaction stages
US4728416A (en) * 1979-11-14 1988-03-01 Ashland Oil, Inc. Cracking blends of gas oil and residual oil

Also Published As

Publication number Publication date
EP0142900A3 (en) 1986-01-22
NL8403539A (en) 1985-06-17
JPS60144388A (en) 1985-07-30
DE3479427D1 (en) 1989-09-21
EP0142900B1 (en) 1989-08-16
EP0142900A2 (en) 1985-05-29

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