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
  • C10G9/007—Visbreaking
• • 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
  • C10G69/00—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one other conversion process
  • C10G69/02—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one other conversion process plural serial stages only
  • C10G69/06—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one other conversion process plural serial stages only including at least one step of thermal cracking in the absence of hydrogen

Definitions

• This invention relates to the preparation of improved residual type fuels and especially to the preparation of residual type fuels meeting the specifications for No. 6 fuel oil, 3500 Redwood No. 1 fuel oil or the like, particularly the viscosity specifications and such sulfur specifications as may be imposed by purchasers and/or local statutes.
• Residual petroleum fractions and certain heavy crudes are products of relatively low value. They are too viscous to employ as low-grade fuel oils. Also their sulfur content is normally so high that these materials cannot be used as low-grade fuel in municipalities that have adopted maximum sulfur specifications for fuels burned in their jurisdiction. It has been proposed previously to subject such residual fractions to visbreaking in order to im prove their viscosity characteristics. This treatment forms a small amount of volatile materials of higher value and also intermediate boiling components, such as furnace oil, which ordinarily are left in the visbroken residual stock in order to decrease its viscosity. Nevertheless, the improvement in viscosity obtained by visbreaking is frequently inadequtae to satisfy the viscosity requirements for residual fuels. Furthermore, the removal of sulfur from visbroken oils is still a problem since the residual fuel produced by visbreaking characteristically has a higher sulfur content than the feed stock charged to the visbreaking process.
• the present invention relates to a combination process including as a first step, subjecting a residual hydrocarbon feed that has a gravity below about 20 API and a sul- 3,324,028 Patented June 6, 1967 fur content of at least about 2 percent to a catalytic hydrodesulfurization treatment at a hydrogen partial pressure in the range of about 400 and 2000 p.s.i.g.
• the temperature during hydrodesulfurization is in the range of about 700 and 850 F., preferably 750 to 850 F., and the space velocity is in the range of about 0.2 and 10, these conditions being so selected that the product from the hydrodesulfurization after removal of furnace oil and lighter hydrocarbons has a pentane-insolubles content which is the same as or below the pentane-insolubles content of the feed stock.
• Hydrodesulfurized residual hydrocarbon product is then subjected to a visbreaking operation in which the reaction conditions are so selected that no more than about 20 percent gasoline is formed.
• the desulfurized and cracked molecules are less viscous than their original or desulfurized uncracked precursors. Accordingly, hydrodesulfurization of residual oils followed by visbreaking, if accompanied by these reactions, will result in a product having an unusually low pour point and requiring unusually small proportions of cutter (diluent) oil to reduce the viscosity to the levels required by typical residual fuel oil specifications.
• the feed stock to the hydrodesulfurization stage of our process may be any petroleum stock containing residual materials, that has an API gravity below about 20 and that has a sulfur content of at least about 2 percent.
• the feed stock may be a whole crude which has an API gravity below about 20. While such low gravity crudes are unusual, they do exist and our process is applicable thereto.
• our process more commonly will be applied to a bottoms fraction of petroleum, i.e., one Which is obtained by distillation of a crude to remove lower boiling materials such as naptha, furnace oil, and/or gas oil. Such a bottoms fraction may be obtained by atmospheric and/ or vacuum distillation of the crude.
• Our invention is particularly applicable to the treatment of straight run residual fractions of crude petroleum having a boiling range above about 1000 F.
• the feed stock should be one which contains sulfur in such large amounts that partial removal is necessary.
• the sulfur content of petroleum stocks suitable for use in the present invention usually will be between about 2 and 8 percent.
• a high sulfur content in the feed stock is important as this indicates a significant number of molecules whose viscosity can be reduced by the combination process of this invention.
• the hydrodesulfurization stage of our invention may be carried out utilizing any suitable hydrodesulfurization catalyst.
• Conventional, commercial hydrodesulfurization catalysts such as cobalt-molybdenum mixtures, nickelcobalt-molybdenum mixtures, nickel-tungsten mixtures, etc. deposited upon porous carriers such as activated alumina, silica-alumina cracking catalysts which have been substantially deactivated, etc., can be used.
• High surface area aluminas such described in U.S. patent ap- 3 plication Serial No. 118,240, filed June 20, 1961, now Patent No. 3,188,174, Kehl and Stewart, are especially advantageous as porous carriers.
• the hydrodesulfurization stage of the combination process of this invention is carried out at a temperature between about 700 and 850 F. at a hydrogen partial pressure between about 400 and 2000 p.s.i.g., preferably 750 to 1500 p.s.i.g., utilizing a space velocity (volume of charge per volume of catalyst per hour) of about 0.2 and and preferably about 0.5 and 2.
• the hydrogen gas which is used during the hydrodesulfuriaztion is circulated at a rate between about 2000 and 15,000 s.c.f./bbl. of feed and preferably between about 5000 and 10,000 s.c.f./bbl.
• the hydrogen purity may vary from about 60 to 100 percent hydrogen.
• the hydrogen is recycled, which is customary, it is desirable to provide for bleeding-off a portion of the recycle gas and to add make-up hydrogen in order to maintain the hydrogen purity within the range specified. Satisfactory removal of hydrogen sulfide from the recycled gas will ordinarily be accomplished by such bleed-off procedures.
• the recycle gas may be washed or otherwise treated in known manner to reduce the hydrogen sulfide content thereof prior to recycling. The objective during hydrodesulfurization is to remove sulfur without concomitant cracking of the hydrocarbons present in the feed stock. To accomplish this, we utilize relatively mild hydrodesulfurization conditions.
• the temperature and space velocity are selected within the range specified which will result in a product having a pentane-insolubles content that is no greater than the pentane-insolubles content of the feed stock.
• the pentane-insolubles content referred to is determined by the standard ASTM D-893 procedure. In general, this test measures the proportion of material that is insoluble in n-pentame and is indicative of high molecular weight, polynuclear, aromatic compounds, such as asphaltenes.
• the entire hydrodesulfurized product, or alternatively, the residual portion of the hydrodesulfurized product free from furnace oil and lighter materials, is then subjected to the visbreaking stage of the combination process of this invention.
• the visbreaking operation is carried out at a temperature between about 800 and 1000 F., and preferably between about 870 and 950 F.
• the pressure during visbreaking is maintained between about 50 and 1000 p.s.i.g.
• the coil volumes should be between about 0.012 and 0.050 cubic feet of coil volume above 750 F. per bar-rel of throughput per 24-hour day.
• the reaction conditions are selected within the ranges specified so as to result in less than about 20 percent formation of hydrocarbons boiling in the naphtha or gasoline range.
• the product from the visbreaking operation may be subjected to distillation to remove lower boiling, more valuable materials formed during visbreaking.
• these materials if the lower boiling materials formed during hydrodesulfurization were not removed before visbreaking, these materials, a well as those formed during visbreaking, may be recovered and used as naphtha, furnace oil, etc.
• the low boiling materials formed during hydrodesulfurization are removed prior to the visbreaking operation, then similar materials are formed during visbreaking, and it is frequently advantageous to separate them, at least in part, from the lower value residual fraction. If these lower boiling materials are removed after visbreaking, it may be necessary to adjust the extent of removal in order to leave a residual fraction having a viscosity meeting the specifications for the residual fuel oil which is desired as a final product.
• Example I A Kuwait vacuum residue having the properties shown in column A of Table I was subjected to visbreaking at a temperature of 930 F., at a pressure of 200 p.s.i.g. with 0.020 cubic feet of coil volume above 750 F. per barrel throughput per day. The product from visbreaking was subjected to a distillation to remove components boiling below 400 F. and to leave a residual bottoms fraction boiling above 400 F. The properties of this product are shown in column B, Table I.
• This hydrodesulfurization was carried out at a temperature of 750 F., a hydrogen pressure of 1000 p.s.i.g., a space velocity (LHSV) of 1.0, and a hydrogen recycle rate of 10,000 s.c.f./bbl.
• a hydrogen pressure 1000 p.s.i.g., a space velocity (LHSV) of 1.0
• LHSV space velocity
• a process for manufacturing heavy fuel oils of improved quality from heavy petroleum oils having objectionabl y high viscosities and sulfur contents comprising subjecting a residual hydrocarbon charge stock that has a gravity below about 20 API and a sulfur content of at least about 2 percent, to catalytic hydrodesulfurization at a hydrogen partial pressure below about 2000 p.s.i.g., at a temperature between about 700 F. and 850 F.
• the temperature and space velocity being selected within the ranges specified to yield principally a residual product free from furnace oil and lighter materials that has a pentane-insolubles content that is not greater than the pentane-insolubles content of the charge stock, said residual product having a somewhat reduced viscosity, sulfur content and pour point and being characterized by an increased susceptibility to viscosity reduction by visbreaking, and subjecting at least the residual portion of the hydrodesulfurized product to .a visbreaking treatment at a temperature between about 800 F. and 1000 F., a pressure between about 50 and 1000 p.s.i.g., and with a coil volume of between about 0.012 and 0.050 cubic feet of coil volume above 750 F.
• the process for manufacturing heavy fuel oils of improved quality from heavy petroleum oils having objectionably high viscosities and sulfur contents comprises subjecting a straight run residual fraction of petroleum that has a gravity below about 20 API and a sulfur content of at least about 2 percent, to catalytic hydrodesulfurization at a hydrogen partial pressure below about 2000 p.s.i.g., at a temperature between about 700 F. and 850 F.
• the temperature and space velocity being selected within the ranges specified to yield principally a product free from furnace oil and lighter materials that has .
• a pentane-insolubles content which is below about the pentane-insolubles content of the charge stock, said residual product having a somewhat reduced viscosity, sulfur content and pour point and being characterized by an increased susceptibility to viscosity reduction by visbreaking, and subjecting at least the residual portion of the hydrodesulfurized product to a visbreaking treatment at a temperature between about 800 F. and 1000 F., a pressure between about 50 and 1000 p.s.i.g., and with a coil volume of between about 0.012 and 0.050 cubic feet of coil volume above 750 F.
• the process for manufacturing heavy fuel oils of improved quality from heavy petroleum oils having objectionably high viscosities and sulfur contents which comprises subjecting a straight run residual petroleum fraction which has a gravity below about 20 API and a sulfur content of at least about 2 percent, a catalytic hydrodesulfurization at a hydrogen partial pressure between about 750 and 1500 p.s.i.g., at a temperature between about 750 F. and 850 F.
• the temperature and space velocity being selected within the ranges specified to yield principally :a product free from furnace oil and lighter materials that has a pentane-insolubles content which is below about the pentane-insolubles content of the charge stock, said residual product having a somewhat reduced viscosity, sulfur content and pour point and being characterized by an increased susceptibility to viscosity reduction by visbreaking, and subjecting at least the residual portion of the hydrodesulfurized product to a visbreaking treatment at a temperature between about 800 F. and 1000 F.. a pressure between about 50 and 1000 p.s.i.g., and with a coil volume of between about 0.012 and 0.050 cubic feet of coil volume above 750 F.

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• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (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)
• Catalysts (AREA)
• Processing Of Solid Wastes (AREA)

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Citations (3)

• 1964
  • 1964-04-22 US US361893A patent/US3324028A/en not_active Expired - Lifetime
• 1965
  • 1965-04-14 DE DEG43349A patent/DE1232300B/de active Pending
  • 1965-04-20 GB GB16488/65A patent/GB1042116A/en not_active Expired
  • 1965-04-21 ES ES0312067A patent/ES312067A1/es not_active Expired
  • 1965-04-21 FR FR13962A patent/FR1432980A/fr not_active Expired
  • 1965-04-22 BE BE662918D patent/BE662918A/xx unknown
  • 1965-04-22 NL NL6505137A patent/NL6505137A/xx unknown

Patent Citations (3)

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