EP1114125A1 - Procede de mise en oeuvre pour craquage catalytique fluide - Google Patents
Procede de mise en oeuvre pour craquage catalytique fluideInfo
- Publication number
- EP1114125A1 EP1114125A1 EP99919918A EP99919918A EP1114125A1 EP 1114125 A1 EP1114125 A1 EP 1114125A1 EP 99919918 A EP99919918 A EP 99919918A EP 99919918 A EP99919918 A EP 99919918A EP 1114125 A1 EP1114125 A1 EP 1114125A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- feeds
- feed
- differ
- risers
- catalytic cracking
- 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.)
- Ceased
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING 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
- C10G11/00—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
- C10G11/14—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid catalysts
- C10G11/18—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid catalysts according to the "fluidised-bed" technique
Definitions
- This invention relates to Fluid Catalytic Cracking (FCC) for producing liquid fuels and light olefins from hydrocarbon mixtures such as petroleum fractions. More particularly, it relates to a nonlinear characteristic of the FCC process that leads to a novel FCC operating strategy for converting hydrocarbon mixtures.
- FCC Fluid Catalytic Cracking
- FCC has been, and will remain for quite some time, the primary conversion process in oil refining.
- a liquid feed mixture is atomized through a nozzle to form small droplets at the bottom of a riser.
- the droplets contact hot regenerated catalyst and are vaporized and cracked to lighter products and coke.
- the vaporized products rise through the riser.
- the catalyst is separated out from the hydrocarbon stream through cyclones. Once separated, the catalyst is stripped in a steam stripper of adsorbed hydrocarbons and then fed to a regenerator where coke is burned off.
- the products are sent to a fractionator for fractionation into several products.
- the catalyst once regenerated, is then fed back into the riser.
- the riser-regenerator assembly is heat balanced in that heat generated by the coke burn is used for feed vaporization and cracking.
- the most common FCC feeds by far are gas oils or vacuum gas oils (VGO) which are hydrocarbon mixtures boiling above about 650°F.
- VGO vacuum gas oils
- refiners need to convert heavy, or highly contaminated oils such as resids, they usually blend a small amount of such heavy oils with the gas oil feeds. Due to a dwindling supply of high-quality crudes, the trend in the petroleum industry is that FCC will have to convert more and more heavy, dirty feeds.
- Such feeds contain a high level of contaminants such as nitrogen, sulfur, metals, polynuclear aromatics, and Conradson Carbon Residue (CCR, a measure of asphaltene content).
- CCR Conradson Carbon Residue
- heavy component is used to include such highly contaminated hydrocarbons as resids, deasphalted oils, lube extracts, tar sands, coal liquids, and the like.
- Such heavy components are added to other feeds containing less heavy components to obtain an FCC feed. These heavy components will become a significant portion of FCC feeds in years to come.
- the present invention discloses a new, improved FCC operating method for cracking feeds of differing quality.
- the present invention is directed to a Fluid Catalytic Cracking process conducted under fluid catalytic cracking conditions comprising injecting into at least one reaction zone of a fluid catalytic cracking unit (FCCU) having one or more risers, a plurality of feeds wherein said plurality of feeds comprises at least one feed ( ⁇ ) and at least another feed ( ⁇ ) wherein said feeds ( ⁇ ) and ( ⁇ ) (a) differ in Conradson Carbon Residue by at least about 2 wt% points; or (b) differ in hydrogen content by at least about 0.2 wt%; or (c) differ in API gravities by at least about 2 points; or (d) differ in nitrogen content by at least about 50 ppm; or (e) differ in carbon-to-hydrogen ratio by at least about 0.3; or (f) differ in mean boiling point by at least about 200°F; and wherein said feeds ( ⁇ ) and ( ⁇ ) are alternately injected and wherein said alternate injection maintains said risers in a cyclic steady state, while the
- the cycle period for alternate injection is judiciously selected to maintain said risers in a cyclic steady state.
- Such cyclic operation can result in a higher time-average conversion and a lower coke selectivity compared to prior art, noncyclic operation.
- the benefit can translate into a higher heavy-component feed cracking capacity at constant liquid yield.
- Figure la Conversion as a function of wt% resid in total feed.
- Figure lb Coke yield as a function of wt% resid in total feed.
- Figure 2a Coke-free kinetic conversion to ⁇ 430°F products vs. wt% resid in feed; 515°C, 8 C/O.
- Figure 2b Coke-free kinetic conversion to ⁇ 650°F products vs. wt% resid in feed; 515°C, 8 C/O.
- Figure 2c Coke selectivity vs. wt% resid in feed; 515°C, 8 C/O.
- Figure 3 a Conversion to ⁇ 430°F products vs. wt% feed hydrogen; 496°C, 6.5 C/O; catalyst A.
- Figure 3b Conversion to ⁇ 430°F products vs. wt% feed hydrogen; 496°C, 6.5 C/O; catalyst B.
- Figure 3c Coke yield vs. wt% feed hydrogen; 496°C, 6.5 C/O; catalyst C.
- Figure 3d Propylene yield vs. wt% feed hydrogen; 496°C, 6.5 C/O; catalyst B.
- Figure 3e Distillate yield vs. wt% feed hydrogen; 496°C, 6.5 C/O; catalyst C.
- Figure 3f Naphtha yield vs. wt% feed hydrogen; 496°C, 6.5 C/O; catalyst C.
- Figure 3g Bottoms yield vs. wt% feed hydrogen; 496°C, 6.5 C/O; catalyst C.
- Figure 3h Butylene yield vs. wt% feed hydrogen; 496°C, 6.5 C/O; catalyst C.
- Figure 1 depicts qualitatively the nonlinear dependencies of conversion and coke yield on the concentration of the resid in the feed.
- the curve for conversion is convex, whereas that for coke yield is concave.
- an FCC unit's coke burning capacity is such that the maximum permissible concentration of the resid is 10 wt%
- the prior art teaches that it is cost effective to charge the unit with a feed containing 10 wt% resid in VGO, point C in Figure la.
- the instant invention teaches a FCC operation that is entirely different from that taught by the prior art.
- the instant invention calls for alternating the concentration of the heavy component between two levels: one is higher than 10 wt% resid and the other is lower.
- the cycle period total combined time for injection of the two alternating feeds
- Such a cycle period is necessarily short enough that the operation of other subsystems (fractionator, regenerator, and stripper) of the FCC unit are not disturbed.
- the other subsystems of the FCC unit are not affected to a degree that would impact the unit or process.
- the feeds are selected from the nonlinear curves of conversion and coke make versus a feed quality index such as wt% resid as shown in Figures la and lb, or wt% feed hydrogen as shown in Figure 3b.
- a feed quality index such as wt% resid as shown in Figures la and lb, or wt% feed hydrogen as shown in Figure 3b.
- such plots can be obtained a priori in small scale routine experiments. Knowing the FCC unit's resid capacity then helps the skilled artisan to select two feeds ( ⁇ ) and ( ⁇ ) for utilization in the instant invention.
- any two feeds which give the 3% increase [see, e.g., (D minus F) on Figure la (D minus F) being the predetermined increase desired] would be selected.
- the increase in liquid yield will be at least about 0.5 wt% on feed, and/or the decrease in coke make will be at least about 0.2 wt% on feed.
- the wt% decrease in coke make would be represented by G minus E on Figure lb.
- any feed quality index can be used to generate the plots, e.g., % resid, hydrogen content, API gravity, nitrogen content, C/H ratio, boiling point, to name a few.
- at least three feeds will be used to generate the plots.
- one example of the invention is to cycle the concentration of the heavy component between 0 and 20 wt% (points A and B in Figure 1) with equal time interval.
- the concentration can be cycled between 5 and 15 wt%.
- the time average resid concentration is 10 wt%.
- the alternating operation gives a higher time average conversion (point D in Figure la) and a lower time average coke yield (point E in Figure lb) than the prior art, nonalternating (uniform feed injection) operation (points F and G) with a feed containing 10 wt% of the heavy component.
- Figures la and lb also imply that the greater the difference in the quality of the two feed components (for instance, gas oil vs. vacuum resid), the larger the benefit (lower coke make and increased liquid yield).
- the benefit stems from the non-linearity shown in Figure 1. That is, the loss caused by the heavy component-containing feed is more than offset by the gain caused by the other feed.
- the heavy component-containing feed is highly contaminated with CCR, nitrogen, polynuclear aromatics, and/or metals. They are also characterized by low hydrogen content or low API gravity.
- the reason the instant invention can maintain the FCC operation in a cyclic steady state is due to the wide disparity in the response times of various FCC subsystems to external disturbances.
- the riser Owing to its short contact time and near plug flow, the riser has a very short response time, typically on the order of 5 seconds.
- the regenerator is much more sluggish, with response time typically on the order of 30 minutes.
- the response times of stripper and fractionator are also orders of magnitude longer than that of the riser. If, for example, each of the two feeds is injected for 20 seconds (that is, the cycle period is 40 seconds), then the riser can quickly equilibrate itself to a new steady state long before the subsequent feed switch. Thus, the riser is essentially operated between two steady states.
- the riser is referred to as being in a cyclic steady state.
- the 40 second cycle period is too short for the sluggish regenerator to respond.
- the fluctuations caused by feed cycling will be quickly smoothed out, and the regenerator basically is in a steady state.
- the stripper and fractionator For instance, the liquid holdup, heavy vapor- liquid traffic, and reflux in the fractionator would quickly damp out any high frequency fluctuations.
- the preferred feed cycle period may be symmetrical where each feed is fed for the same amount of time, or asymmetrical where the feeds are fed for different periods of time.
- the feed cycle times are readily selected by the skilled artisan based upon the response times of the risers, regenerator, and fractionator. Selection should preferably be based upon the longest time permitted by the regenerator operation and product recovery considerations.
- the instant invention offers many choices in both feed considerations. While the above example alternates two feeds with equal time intervals, this symmetric mode of feed switching may not necessarily give the maximum benefit. In some cases, asymmetric switching may be preferred; that is, each feed is injected for a different amount of time. For instance, in the above example where the cycle period is 40 seconds, the individual periods for the straight
- VGO and 20 wt%-resid-in-VGO feeds may be 15 and 25 seconds, respectively.
- the feed concentrations of the heavy component used in the instant operation may also be chosen for maximum benefit.
- the instant operation offers many degrees of freedom for process optimization. Typical cycle times can range from 10 seconds to 3 minutes, preferably, 20 seconds to 2 minutes.
- the FCCU is operated by continuously repeating each cycle.
- the feed pair may comprise a naphtha-rich stock and naphtha-lean stock.
- Nonlimiting examples of feed property yardsticks for suitable feeds are (a) hydrogen content (differing by at least about 0.2 wt%), (b) carbon-to-hydrogen ratio (differing by at least about 0.3), (c) API gravity (differing by at least about 2 points), (d) nitrogen content (differing by at least about 50 ppm), (e) mean boiling point (differing by at least about 200°F), (f) a CCR (differing by at least about 2 wt%), etc.
- the instant invention method can be used for any two feeds whose qualities [(a) to (f)] are sufficiently different, it is particularly suited for converting heavy, low quality hydrocarbon mixtures. It gives a higher time-average liquid yield and a lower time average coke make than those obtained from prior art, nonalternating operations. Additionally, in many cases, a higher time average propylene yield than that obtained in nonalternating operation can be obtained.
- the present method can be implemented in different cracking reactor configurations, including but not limited to short contact time risers, fluidized reactors, and downflow reactors.
- the invention can also be practiced with greater than two feeds.
- segregated is meant physically separated or spatially separated at a distance effectively yielding two separate reaction zones.
- feeds ⁇ and ⁇ can be alternately injected into the first riser and feeds ⁇ and ⁇ alternately injected into the second riser in accordance with the feed selection criteria [(a) to (f)] hereinbefore discussed.
- the products from each riser may then be combined.
- any combination of the three feeds where two feeds are alternately injected into each riser can be utilized.
- ⁇ and ⁇ can be alternately injected into one reaction zone and ⁇ and ⁇ into the second reaction zone.
- ⁇ and ⁇ can be alternately injected into one reaction zone of a first riser and ⁇ and ⁇ can be injected into separate reaction zones of the same riser or into a second riser as follows: (i) simultaneously injecting into a single reaction zone of a single riser feed ( ⁇ ) from at least one injection nozzle of said riser and feed ( ⁇ ) from the remaining nozzles of the riser; or (ii) simultaneously injecting feed ( ⁇ ) into at least one reaction zone of a second riser and feed ( ⁇ ) into another reaction zone of the second riser of the FCCU.
- the cleanest, most crackable feed will be injected into each riser along with one of the two remaining feeds in each alternating riser.
- cleanest, most crackable feed is meant that feed having the highest hydrogen content, or the highest API or the lowest nitrogen content, the lowest carbon-to-hydrogen ratio or the lowest mean boiling point or lowest CCR as compared to the other two feeds.
- the criteria for the feeds are that the two feeds injected into the same riser must meet the criteria previously described herein [(a) to (f)].
- the feeds injected into the same riser must (a) have CCR differing by at least 2 wt% points; or (b) differ in hydrogen content by at least about 0.2 wt%; or (c) differ in API gravities by at least about 2 points; or (d) differ in nitrogen content by at least about 50 ppm; or (e) differ in carbon-to-hydrogen ratio by at least about 0.3; or (f) differ in mean boiling point by at least about 200°F.
- the cracking experiments were conducted in an FCC pilot unit at 515°C and a catalyst-to-oil (C/O) ratio of 8.
- the catalyst is metered from a regenerated catalyst hopper into a riser using a screw feeder.
- the hot catalyst contacts incoming oil and gaseous nitrogen and is carried up the riser where the oil is cracked.
- the spent catalyst and reactor products enter a separation zone.
- the gases continue overhead to a product recovery system and the catalyst drops down a stripper and into a spent catalyst hopper.
- the gaseous products are cooled to produce a C 5 + liquid product and a C 5 " product gas.
- Figures 2a and 2b show, respectively, the coke-free kinetic conversions to ⁇ 430°F and ⁇ 650°F products as functions of the resid content of the total feed.
- Figure 2c depicts a similar plot for coke yield. From these plots one can determine the time average kinetic conversion and coke selectivity. It follows from Figures 2a to 2c that ⁇ (for conversions to ⁇ 430°F and ⁇ 650°F products) are higher than those obtained from the 16% VR-in-VGO feed, while S is lower. Each data point is the average of two or three runs. Specifically, the 430 and 650 coke-free kinetic conversions were improved by 5.3% and 7.5%, respectively. That is, in the case of 430 coke-free conversion, the ratio of ⁇ to ⁇ (for the 16% VR-in-VGO feed) is 1.053. And the coke selectivity is lowered by 12.2%.
- the catalyst was the same as in Example 1 except that it was not impregnated with Ni. Cracking conditions are 5 C/O and 515°C. The 430 and 650 kinetic conversions were improved by 8.9% and 10.7%, respectively, with the coke selectivity being decreased by 4.4%. The propylene yield was improved by 6.5%.
- the feed components used in this example are a hydrotreated VGO (HTGO) and a butane-deasphalted resid (DAO).
- HTGO hydrotreated VGO
- DAO butane-deasphalted resid Table 2 lists the compositions and properties of the feed blends.
- a vacuum gas oil was separated into different fractions having varying hydrogen contents via solvent extraction. These resulting fractions were each cracked at 496°C, 6.5 C/O, and 80 g/m oil rate over several commercial catalysts, designated as catalysts A, B, and C. Table 3 lists the properties of these catalysts.
- the hydrogen content of the feed was used as the feed quality measure.
- the data shown in Figures 3 a to 3 h were obtained for feeds whose hydrogen contents are 10.4, 12.1, 13.6, and 13.8 wt%. The results shown in the Figures clearly show the desired nonlinear effects.
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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
La présente invention concerne un procédé de craquage catalytique fluide, conduit dans des conditions de craquage catalytique fluidique, par injection, dans au moins une zone de réaction d'une unité de craquage catalytique fluide pourvue d'un ou plusieurs élévateurs de catalyseur, d'une pluralité de charges, ladite pluralité de charges comprenant au moins une charge (α) et au moins une autre charge (β). Ces charges (α) et (β) (a) diffèrent en résidu Conradson d'au moins 2 % en poids environ; ou (b) diffèrent en teneur en hydrogène d'au moins 0,2 % en poids environ ; ou (c) diffèrent en densité API d'au moins 2 points environ, ou (d) diffèrent en teneur en azote d'au moins 50 ppm ; ou (e) diffèrent en rapport carbone/hydrogène d'au moins 0,3 environ ; ou (f) diffèrent en point d'ébullition moyen d'au moins 200 °F environ ; et lesquelles charges (α) et (β) sont injectées en alternance, injection alternée qui permet de maintenir les élévateurs dans un état cyclique stable, lorsque le reste de l'unité de craquage catalytique fluide est dans un état stable.
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US6787098A | 1998-04-28 | 1998-04-28 | |
US67870 | 1998-04-28 | ||
1998-05-07 | |||
US09/294,951 US6156189A (en) | 1998-04-28 | 1999-04-20 | Operating method for fluid catalytic cracking involving alternating feed injection |
PCT/US1999/008648 WO1999055802A1 (fr) | 1998-04-28 | 1999-04-20 | Procede de mise en oeuvre pour craquage catalytique fluide |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1114125A1 true EP1114125A1 (fr) | 2001-07-11 |
Family
ID=26748361
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99919918A Ceased EP1114125A1 (fr) | 1998-04-28 | 1999-04-20 | Procede de mise en oeuvre pour craquage catalytique fluide |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1114125A1 (fr) |
JP (1) | JP2004503605A (fr) |
CA (1) | CA2328978A1 (fr) |
WO (1) | WO1999055802A1 (fr) |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA1327177C (fr) * | 1988-11-18 | 1994-02-22 | Alan R. Goelzer | Procede permettant de maximiser de facon selective la distribution d'hydrocarbures dans une installation de craquage catalytique a lit fluidise |
CA2008978A1 (fr) * | 1989-02-06 | 1990-08-06 | Alan R. Goelzer | Procede pour la craquage catalytique d'hydrocarbures |
US5098554A (en) * | 1990-03-02 | 1992-03-24 | Chevron Research Company | Expedient method for altering the yield distribution from fluid catalytic cracking units |
-
1999
- 1999-04-20 CA CA002328978A patent/CA2328978A1/fr not_active Abandoned
- 1999-04-20 JP JP2000545953A patent/JP2004503605A/ja active Pending
- 1999-04-20 EP EP99919918A patent/EP1114125A1/fr not_active Ceased
- 1999-04-20 WO PCT/US1999/008648 patent/WO1999055802A1/fr not_active Application Discontinuation
Non-Patent Citations (1)
Title |
---|
See references of WO9955802A1 * |
Also Published As
Publication number | Publication date |
---|---|
CA2328978A1 (fr) | 1999-11-04 |
WO1999055802A8 (fr) | 2001-04-26 |
WO1999055802A1 (fr) | 1999-11-04 |
JP2004503605A (ja) | 2004-02-05 |
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