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
  • C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
  • C10G9/005—Coking (in order to produce liquid products mainly)
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
  • C10B55/00—Coking mineral oils, bitumen, tar, and the like or mixtures thereof with solid carbonaceous material

Definitions

• the light fraction is separately cracked in a first riser reaction zone at high temperature and high conversion for control of light cycle gas oil product pour point.
• the heavy fraction is separately cracked in a second riser react1on zone at moderate temperature and moderate conversion for control of naphtha to light cycle gas oil product ratio.
• the present invention relates to fluidized catalytic cracking of relatively heavy petroleum fractions into useful products including naphtha suitable for use as motor gasoline and light cycle gas oil suitable for use in furnace oil. More particularly, the present invention relates to an improved fluidized catalytic cracking process for conversion of highly paraflinic or waxy petroleum fractions into products having commercially desirable properties.
• Fluidized catalytic cracking processes for conversion of petroleum fractions are well known in the prior art.
• Such cracking processes are commercially employed for conversion of relatively heavy hydrocarbons such as atmospheric gas oils, vacuum gas oils, topped crudes, residuum, etc., into commercially more valuable products such as olefins and isoparaflins for alkylation process charge stock, naphthas for gasoline blending components, light cycle gas oils for furnace oils, etc.
• Such fluidized catalytic cracking processes generally comprise process steps including contacting a hot, regenerated catalyst with a hydrocarbon feed in a reaction zone under cracking conditions; separating cracked hydrocarbon vapors from used cracking catalyst; stripping volatile hydrocarbons from used cracking catalyst with a stripping vapor; regenerating stripped catalyst by burning carbonaceous deposits, e.g., coke, therefrom with a molecular oxygen containing gas; returning regenerated catalyst to said reaction zone for reaction with additional amounts of hydrocarbon feed; and separating cracked hydrocarbon vapors into fractions including a gas product, a naphtha product, a light cycle oil product and one or more heavier fractions boiling above the light cycle oil boiling range.
• Furnace oils which are also known as fuel oil No. 1, fuel oil N0. 2, and heating oil, are particularly useful for home and industrial heating purposes. The end use of these oils requires that they have a pour point of 0 F., or lower.
• a conventional source of furnace oil is from the efiluent stream from a catalytic cracker.
• light cycle gas oils often serve as blending stock for these furnace oils.
• Fuel oil No. 2 and heating oil which come within the broad definition of furnace oil, have a pour point requirement of 0 F., and a boiling range of about 430-650" F.
• Another furnace oil is fuel oil No. 1 which typically can have a 430-550" F. boiling range with a pour point of about 30 F.
• light cycle gas oils meet most specifications for furnace oils, they usually must be subjected to some further processing to provide a saleable product. Typically, caustic washing is required to complete the processing.
• Low sulfur content crude oils may be processed for production of low sulfur content furnace oils.
• low-sulfur crudes are highly desirable sources of gas oils because of their sulfur content, they are often highly paraifinic which results in a substantially higher pour point for gas oils obtained therefrom than from crude oils employed heretofore.
• Light cycle gas oils obtained from catalytic cracking of these waxy gas oils also have high pour points which necessitate additional processing or substantial modifications to present processing to obtain the furnace oil pour point specification of 0 F. and below.
• improved cracking catalysts including zeolitic molecular sieves and high alumina catalysts.
• Such improved catalysts have higher conversion activity wherein components of a hydrocarbon charge stock boiling higher than about 430 F. are converted into hydrocarbons boiling below 430 F. and coke. Additionally, such improved catalysts have increased naphtha selectivity wherein a greater portion of the hydrocarbons converted appear as naphtha.
• Such contact has been found most effective when the catalyst is dispersed in a vapor stream of the hydrocarbon charge stock which is moving with suflicient velocity to maintain the catalyst entrained as a dilute suspension with a minimum of back mixing along the path of flow.
• Such contact between catalyst and hydrocarbon vapors may be effectively obtained employing elongated reaction conduits having a substantial vertical component, such as are shown in US. Pat. 3,448,037, issued June 3, 1969.
• One or more such elongated reaction conduits may be employed in a fluidized catalytic cracking unit.
• reaction conditions for the conversion of relatively heavy petroleum fractions into desired cracked products include reaction conduitoutlet temperatures in the range of 850-1200 F., preferably 925-1000 F. or higher.
• Reaction zone pressures of from about 5-50 p.s.i. g., catalyst oil weight ratios of about 2-20 lbs. of catalyst per pound of oil, vapor residence times in said reaction conduits of about 05-10 seconds and preferably 1-5 seconds, superficial vapor velocities near reaction conduit entrances of about 10- 25 feet per second and velocities near the outlets of about 20-60 feet per second.
• Regeneration of used cracking catalyst wherein carbonaceous deposits are burned from the catalyst with molecular oxygen, may be carried out at temperatures in the range of 1100-1500" F. and at regeneration vessel dilute phase pressures in the range of 5-50 p.s.i.g., preferably 20-40 p.s.i.g. Combinations of the above reaction conditions may be employed to obtain conversions of the hydrocarbon charge in the range of -95 percent and preferably -90 percent. It is also known, under certain conditions, to recycle part or all of the unconverted hydrocarbons recovered from the reaction zone effluent to the reaction zone for additional conversion.
• Such fluidized catalytic cracking processes are effective for converting a variety of petroleum fractions and other hydrocarbon oils into desirable products including C -C olefins and isoparaflins, naphtha boiling range hydrocarbons having relatively high octane values, and light cycle oil falling in the boiling range of about 400 to 650 F. suitable for use as furnace oil blend stock.
• C -C olefins and isoparaflins naphtha boiling range hydrocarbons having relatively high octane values
• light cycle oil falling in the boiling range of about 400 to 650 F. suitable for use as furnace oil blend stock.
• wax high molecular weight paraflinic hydrocarbons
• paraflinic petroleum fractions are characterized by having a high pour point temperature which makes them unattractive for use as furnace oil blend stock as the oils tend to become solids at relatively high temperatures thus making them difficult to transport and store in cold climates where furnace oils are commonly used.
• Light cycle oil products from a fluid cracking process wherein paraffinic petroleum fractions are charged also tend to have pour point temperatures substantially above standard accepted values, about F. or less, of furnace oils for which therse light cycle oils are otherwise Well suited.
• Pour point temperatures for light cycle oil products of parafiinic petroleum fractions may be lowered by increasing the severity of the fluid cracking reaction. However, increasing or decreasing conversion severity of a 650 F.+ gas oil above or below about the 60-70% range decreases the yield of light cycle gas oil product.
• a fluidized catalytic cracking process for converting paraflinic hydrocarbon fractions to produce good yields of high octane naphthas and light cycle gas oils having low pour point temperatures.
• Such improved process comprises separating a paraifinic hydrocarbon fraction having a pour point of greater than 0 F. into a light fraction boiling above about 400 F. and below about 650 F. and a heavy fraction boiling above about 650 F.
• the light fraction is cracked in a first dilute phase riser cracking zone in the presence of a cracking catalyst under severe conditions to convert at least about 75% of such light fraction into C -C hydrocarbons, naphtha, and coke.
• the heavy fraction is cracked in a second dilute phase riser cracking zone under less severe conditions for cracking of a substantial portion of such heavy fractions into hydrocarbons boiling below 650 F. and including the production of a substantial amount of naphtha and of light cycle gas oil boiling in the 400650 F. range.
• Eflluent streams from the first and second dilute phase reaction zones are combined in a common disengaging vessel for separation of cracked hydrocarbons from used catalyst.
• Cracked hydrocarbons from the disengaging vessel are separated in a product fractionation zone into at least a gas fraction, a naphtha fraction, a light cycle gas oil fraction, and one or more fractions higher boiling than light cycle gas oil.
• Reaction conditions in the first dilute phase cracking zone are controlled to maintain the pour point temperature of the light cycle gas oil from the product fractionation zone at a selected value less than +l0 F.
• Reaction conditions in the second dilute phase reaction zone are controlled to produce the desired product distribution from the product fractionation zone.
• One advantage of the present invention is the pour point temperature of the product light cycle gas oil may be maintained within an acceptable commercial range for use as a furnace oil blending stock and simultaneously the product ratio of naphtha to light cycle gas oil may be varied over a wide range of values.
• Another method for obtaining furnace oils having 0 F. pour point from high pour point light cycle gas oil comprises fractionating such light cycle gas oils into a light fraction having an ASTM distillation end point temperature of less than 650 F. and a heavier fraction.
• the light fraction end point temperature is adjusted to maintain the pour point temperature below 0 F., and such light fraction is employed as furnace oil.
• This fractionation process substantially decreases the amount of furnace oil which may be obtained from a high pour point light cycle gas oil.
• Charge stocks within the contemplation of the present invention include those petroleum fractions and hydrocarbon streams containing substantial amounts of long straight chain waxy paraflin hydrocarbons and comprising a high pour point temperature light fraction boiling within the 400-650 F. range and a heavy fraction boiling above about 650
• Examples of such charge stocks include Waxy crudes. topped crudes, gas oils, etc. as well as other highly paraffinic hydrocarbon streams.
• the waxy paraflin content of such charge stocks imparts high pour point temperatures thereto such that the light fractions of such charge stocks, although boiling Within the furnace oil :boiling range, have unacceptable high pour point temperatures, e.g., above +10 'F., for use as furnace oil blend stocks.
• the high pour point light fraction of such a waxy charge stock is of a character such that when charged to a conventional fluid catalytic cracking process, the pour point temperature of produced light cycle gas oil increases substantially.
• Such high pour point light cycle gas oil is less useful or unacceptable as a furnace oil blend stock.
• the steps include:
• step (e) Collecting used catalyst from step (d) in said fluidized bed, and withdrawing, stripping, regenerating, and introducing such catalyst into steps. (b) and (c) above;
• the pour point of the light cycle gas oil components produced from cracking the light fraction of the waxy charge stock is substantially affected by the temperature employed and degree of conversion obtained in the cracking reaction. That is, the pour point temperature decreases with increased conversion and increased reaction temperature. Additionally the octane of naphtha produced from cracking the light fraction of the waxy charge stock increases with increased reaction temperatures. Consequently, by cracking the light fraction of the waxy charge stock at a high temperature, above about 950 F., to a high degree of conversion, at least about 80%, the light fraction may be converted into substantial yields of high octane naphtha and relatively low pour point temperature light cycle oil.
• the pour point temperature of a light cycle gas oil obtained from cracking the heavy fraction of a waxy charge stock, is substantially not dependent upon the severity or temperature of the cracking reaction.
• the heavy fraction may be cracked over a wide range of conversions and the pour point of the light cycle gas oil component is substantially unaffected while the volume of light cycle gas oil varies substantiall Aiz cording to the present invention, the light fraction of the waxy charge stock is cracked to a high conversion at a high temperature for production of a substantial amount of high octane naphtha and a small amount of light cycle gas oil component and the heavy fraction of the waxy charge stock is cracked to moderate conversion for production of substantial amounts of both naphtha and low pour point light cycle gas oil.
• the naphtha product comprises naphtha obtained from cracking both light and heavy fractions of the waxy charge stock and the llght cycle gas oil product comprises light cycle gas oil components from both the light and cracked heavy fractions of the waxy charge stock.
• the light cycle gas oil product obtained from the process of this invention is one suitable for use as furnace oil blend stock, has a boiling range of from about 400 to about 650 F. and a pour point temperature of less than F., preferably less than about 0 F.
• Pour point of the product light cycle gas oil is controlled, according to the present invention, by adjusting conversion and reaction temperature of the light fraction cracking step to obtain the desired pour point temperature for the product light cycle gas oil.
• the ratio of product naphtha to product light cycle gas oil is controlled by adjusting the conversion of the heavy fraction of the waxy crude charge stock.
• a fluidized catalytic cracking unit configuration useful for practicing the method of the present invention may be one such as is shown in US. Pat. 3,448,037, patented June 3, 1969.
• process configurations employing a plurality of riser reaction zones may also be used within the contemplation of the present invention.
• Catalysts contemplated for use in the present invention are those fluid catalytic cracking catalysts having high activity for conversion of hydrocarbons boiling above about 430 F. into hydrocarbons boiling below about 430 F. and coke. Also, it is contemplated that such catalysts will have high selectivity for production of naptha boiling range hydrocarbons from that portion of the hydrocarbon which are converted.
• zeolite catalysts, high alumina catalyst, and other catalysts having the desired high conversion activity and naphtha selectivity may be employed within the con- 6 templation of the present invention.
• the zeolitic catalyst as described in referenced patent US. 3,448,037, are particularly useful as catalysts for the practice of the present invention.
• Such composite crystalline zeolite catalysts comprise about 1 to 25 weight percent zeolite, 10 to 50 weight percent alumina, and the remainder silica.
• the zeolitic catalysts, which form the high activity components of the catalyst are alkaline metal, crystalline alumino-silicate which have been treated to replace all or at least a substantial portion of the original alkaline metal ions with other cations such as hydrogen and/or a metal or combination of metals, such as barium, calcium, magnesium, manganese, or rare earth metals such as cerium, lanthanum, neodymium, praseodymium, samarium, and yttrium.
• a waxy charge stock is separated into a light fraction and a heavy fraction.
• the fractions are converted in the presence of high activity cracking catalysts through separate elongated riser reaction zones.
• the light fraction comprising hydrocarbons boiling in the range of about 400 to about 650 F. and having a pour point of about +10 F. or higher, conversion is undertaken at a temperature ranging from about 950 F. to about 1100 F.
• feed preheat temperature in the range of 350-800 F.
• catalyst to oil weight ratio within the range of about 2:1 to 20:1
• residence time of hydrocarbon within the riser of from about 1 to 10 seconds and preferably from 1 to 5 seconds
• superficial vapor velocities of from about 10 to 60 feet per second
• reaction zone pressures in the range of about 5 to 50 p.s.i.g.
• reaction conditions may be varied within the ranges given to obtain conversion and reaction temperatures sufficient to yield a light cycle gas oil product from the process of the present invention boiling in the range of from about 400 to about 650 F. and having a pour point temperature of +l0 F. or lower, preferably 0 F. or lower.
• conversion is undertaken in a second elongated riser reaction zone at a temperature of from about 900 to 1050 F. within the heavy fraction undergoes a conversion within the range of about 60 to 85%, preferably; in the range of about 65 to 75%.
• Conversion of the heavy fraction with the range stated above is accomplished by operating as follows: heavy fraction preheat temperature in the range of about 450 to 750 F., catalyst to oil weight ratios in the range of 2:1 to 20:1, superficial vapor velocities in the second riser of from about 10 to 60 feet per second, reaction zone pressure of about 5 to 50 p.s.i.g., residence time of from about 1 to 10 seconds and preferably 1 to 5 seconds.
• heavy fraction is subjected to conversion at a level to provide a desired volume ratio of light cycle gas oil to naphtha products recovered from the process.
• Efiiuent from the first and second riser reaction zones comprising vaporous reaction products and catalyst, discharge into a disengaging space above a fluidized bed of catalyst.
• hydrocarbon vapors separate from used catalyst and the catalyst enters the fluidized bed.
• used catalyst is withdrawn for stripping and regeneration according to methods well known in the art. Cracked hydrocarbon vapors, substantially free of catalyst, are recovered from the disengaging space and charged to a product fractionatron zone.
• cracked hydrocarbons are separated into at least a gaseous fraction, a naphtha fraction, a light cycle gas oil fraction, and one or more fractions heavier than light cycle gas oil.
• the 7 naphtha fraction generally boils within the range of about C 430" F. and is suitable for use as gasoline blend stock.
• the light cycle gas oil boils within the range of about 400650 F;. and has a pour point less than F., preferably less than 0 F. Such light cycle gas oil is useful as furnace oil blend stock.
• a small portion of the cracked product comprises hydrocarbons higher boiling than light cycle gas oil.
• all or a portion of such heavier hydrocarbon may be recycled to a reaction zone for addition conversion.
• such heavier hydrocarbons are yielded as products and all conversion of charge stock is achieved upon a one-pass basis.
• Feed preheat F. 600 Riser outlet, F. 1015 Residence time, seconds 4 Average riser vapor velocity, feet per second Conversion, vol. percent 71.3
• Octane values of the debutanized naphtha are as follows:
• Light cycle gas oil pour point temperature is +40 R, which is substantially higher than is acceptable for furnace oil blend stock.
• the light fraction comprising 25 volume percent of the topped crude and the heavy fraction comprising 75 volume percent are cracked in separate elongated riser reaction zones under cracking conditions as follows:
• Octane values of the debutanized naphtha are as follows:
• Light cycle gas oil pour point temperature is 5 R, which is well within the acceptable range for a furnace oil blend stock.
• a waxy charge stock containing high pour point components boiling in the furnace oil range may be converted in a fluidized catalytic cracking process to yield substantial amounts of high octane naphtha and low pour point light cycle oil.
• a fluidized catalytic cracking process for converting a waxy hydrocarbon charge stock and producing substantial yields of high octane naphtha and low pour point light cycle oil which comprise:
• step (b) reacting said light fraction, in a first elongated riser reaction zone in the presence of a hot regenerated cracking catalyst at a reaction temperature of from about 950 F. to about 1100 F., and at a conversion of at least about for controlling pour point of light cycle gas oil of step (g) at +10 F. or less;
• step (c) reacting said heavy fraction, in a second elongated riser reaction zone inthe presence of a hot regenerated cracking catalyst at a reaction temperature of from about 900? F. to about 1000 F. and at a conversion of from about 60% to about 80% for controlling the volume ratio of naphtha to light cycle gas oil recovered in step (g);
• step (a) is from about 1000 F. to about 1100 F., wherein light fraction conversion of step (a) is from about 85% to about 95%, and wherein pour point of light cycle gas oil of step (g) is F. or less.
• operating conditions in said first elongated riser reaction zone include, light fraction preheat temperature in the range of about 350- 850 F., catalyst to oil weight ratio of from about 2:1 to 20: l, hydrocarbon residence time within said first riser of about 1-10 seconds, superficial vapor velocity of about 10-60 feet per second, and disengaging space pressure of about -50 p.s.i.g., and wherein such operating conditions are adjusted to obtain light fraction conversion of from about 85 to about 95%.
• operating condition in said second elongated riser reaction zone include, heavy fraction preheat temperature in the range of about 450- 750 F., catalyst to oil weight ratio of from about 2:1 to 20:1, hydrocarbon residence time within said second riser of about l-l0 seconds, superficial vapor velocity of about -60 feet per second, and disengaging space pressure of about 5-50 p.s.i.g., and wherein such operating conditions are adjusted to obtain heavy fraction conversion of from about 60% to about 80% 5.
• a fluidized catalytic cracking process for conversion of a hydrocarbon charge stock comprising a light fraction having a boiling range of about 550-650 F. and a pour point of at least +20 F., and a heavy fraction boiling above 650 R, which process comprises:
• step (b) catalytically cracking said light fraction, in a first dilute phase riser cracking zone, at a temperature of from about 950 F. to about 1100 F. andat a conversion of from about 80% to about 100% for maintaining the pour point of light cycle gas oil of step (e) at a +10 F. or less;
• step (c) catalytically cracking said heavy fraction, in a second dilute phase riser cracking zone, at a temperature of from about 900 F. to about 1000 F. and at a conversion of from about 60% to about 85% for maintaining a selected volume ratio of naphtha to light cycle gas oil in step (e);
• step (b) is from about 1000 F. to about 1100 F., wherein light fraction conversion of step (b) is from about to about and wherein pour point of light cycle gas oil product is 0 F. or less.
• a fluidized catalytic cracking process for conversion of a hydrocarbon charge stock comprising a light fraction having a major portion boiling within the range of a light cycle gas oil product of step (f) and having a pour point greater than said light cycle gas oil product, and a heavy fraction having a major portion boiling above the light cycle gas oil product, which process comprises:
• step (b) catalytically cracking said light fraction in a first dilute phase riser cracking zone, at a temperature of from about 950 -F. to 1100 F. and at a con version of from about 80% to about for controlling the pour point of light cycle gas oil of p
• step (f) fractionating the first hydrocarbon vapor of step (d) and the second hydrocarbon vapor of step (c), in a common fractionation zone, into at least a C and lighter fraction, a debutanized naphtha fraction, a light cycle gas oil fraction, and one or more fractions higher boiling than light cycle gas oil.
• volume ratio of naphtha to light cycle gas oil is within the range of from about 120.3 to about 1:0.15.

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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)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Materials Engineering (AREA)
• Coke Industry (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Working-Up Tar And Pitch (AREA)

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Cited By (9)

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• 1970
  • 1970-12-02 JP JP45105950A patent/JPS4911603B1/ja active Pending
• 1971
  • 1971-12-01 GB GB5585171A patent/GB1365493A/en not_active Expired
  • 1971-12-02 AU AU36442/71A patent/AU442152B2/en not_active Expired
  • 1971-12-02 ZA ZA718091A patent/ZA718091B/xx unknown
  • 1971-12-02 DE DE19712159862 patent/DE2159862A1/de active Pending
• 1973
  • 1973-01-02 US US00320036A patent/US3799864A/en not_active Expired - Lifetime

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