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
  • C10G21/00—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents
  • C10G21/06—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents characterised by the solvent used
• • 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
  • C10G21/00—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents
• • 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
  • C10G21/00—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents
  • C10G21/06—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents characterised by the solvent used
  • C10G21/12—Organic compounds only
• • 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
  • C10G21/00—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents
  • C10G21/06—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents characterised by the solvent used
  • C10G21/12—Organic compounds only
  • C10G21/14—Hydrocarbons
• • 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
  • C10G21/00—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents
  • C10G21/06—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents characterised by the solvent used
  • C10G21/12—Organic compounds only
  • C10G21/27—Organic compounds not provided for in a single one of groups C10G21/14 - C10G21/26

Definitions

• the invention relates to the dewaxing of lubricating oils. More particularly, it relates to the formation of low pour point lube oils which may be utilized in cold climates. These lube oils are produced when wax is removed from the lube oil by means of an autorefrigerative dewaxing solvent combining an olefin and a polar electron acceptor. The removal of waxes by means of these compounds results in the creation of a lube oil which has a low pour point.
• paraffinic crudes are generally used in the production of high quality motor oils, aviation oils, turbine oils and hydraulic oils.
• the parafiinic crudes produce lubricating oils with a relatively high viscosity index.
• the waxy constituents present in these crudes confer upon the libricating oil products excessively high pour points and cloud points. It is essential that these waxy constituents are removed in order to improve the pour point and cloud point of the oil.
• Naphthenic crudes are generally used to make a variety of industrial and process oils which do not require high viscosity indices. These oils are used for such purposes as diesel engine lubricants, transformer oils and spray oils. The natural pour point of these oils is low enough so that dewaxing is not generally required. However, the higher viscosity naphthenic lubes usually require treatment in a dewaxing plant to reduce cloud point to acceptable levels.
• the waxy oil and the solvent are heated to a temperature sufficiently high to secure a single phase of substantially completely miscible ingredients.
• the waxy mixture is then chilled in order to precipitate wax particles or crystals from the solution.
• the chilled mass is filtered in order to segregate the wax particles and further treated to recover the dewaxing solvent.
• This process has generally been effective to the extent that it is capable of producing lube oils which have a lower pour point.
• propane dewaxing which is one of the most widely used dewaxing processes, is limited in that safety hazards prevent the production of lube oils having a pour point lower than about 10 F.
• the main limiting factor determining the resulting pour point after a dewaxing step is the filtration temperature at which the lube oil is dewaxed.
• the minimum chiller temperature which may be utilized is 44 F. which is the normal boiling point of propane. Filtration temperatures are usually 2-4 F. higher than the chiller temperature, so that the minimum practical filtration temperature is about 40 F. Product pour points are usually about 50 F. higher than filtration temperatures. This means that conventional propane dewaxing is substantially limited to a minimum product pour point of about 10 F.
• Propane is widely used as a dewaxing solvent since it also may be used as an autorefrigerant. That is to say, propane has a dual function; acting as an oil solvent or diluent and chilling the lube oil mixture.
• propane has a dual function; acting as an oil solvent or diluent and chilling the lube oil mixture.
• Typical of many U.S. patents disclosing this propane dewaxing technique is U.S. 3,291,718.
• Indicative of those patents which make use of ketone as a dewaxing solvent is U.S. 3,192,125.
• Lubricating and specialty oils which boil in the range of about 400 to 900 F. initially and 600 to 1050+ F. finally, may effectively be treated with the process of the instant invention.
• the purpose of the olefin-polar electron acceptor mixture is to serve as a solvent for the oil as an anti-solvent for the wax and also to chill the mixture by autorefrigeration. The removal of these waxes serves to substantially lower the pour point of the oils.
• the preferred olefins are those having 2 to 5 carbon atoms, most preferably propylene and butylene.
• a wide variety of polar electron acceptors may be utilized; it is preferred to use those readily available polar electron acceptors which include nitriles, S0 and its derivatives, nitroalkanes and ketones.
• the mixture comprises about to 40 wt. percent of the olefin and about 10 to 60 wt. percent of the polar electron acceptor.
• the mixture is added in the liquid phase; the oil is also maintained in the liquid phase. Temperatures at which the liquid mixture may be added vary between 50 and F. and pressures of 50 and 300 p.s.i.a. for the whole mixture including wax and oil, may be utilized.
• the oil is filtered and a substantially dewaxed oil is recovered which may pour between a temperature of 0 and -20 F. depending on the filtration temperature.
• waxy oil feed boiling between 700 and 1025+ F. initially and finally between 750 to 1050+ F. which may previously have been subjected to solvent extraction with a suitable solvent such as phenol, furfural, nitrobenzene or other well-known solvent for extraction and/or deasphalting as well as other procedures such as hydrotreating, is mixed continuously with the dewaxing solvent of the instant invention.
• suitable olefinic autorefrigerants and solvents include ethylene, propylene, butylene or mixtures thereof with propylene being the most preferred olefin.
• the other part of the mixture will be a polar electron acceptor such as S nitroalkanes, ketones, such as acetone and nitriles. It should be emphasized that these are merely preferred polar electron acceptors and the invention is intended to include the various other polar electron acceptors which are satisfactory in varying degrees.
• a small quantity of dewaxing aid may also be added to the solvent mixture; this would include copolymers of ethylene and vinyl acetate; also condensates of chlorinated paraffin with naphthalene or benzene; also polyacrylates and polymethacrylates of higher aliphatic alcohols.
• the solvent mixture of the in stant invention is added in an amount of 50 to 80, preferably 50 to 60 LV percent.
• the mixture is about 75 to 63 wt. percent olefin and about to 37 wt. percent of polar molecule. Temperature during addition of the mixture to the oil is about 70 to 120 F. and pressure is about 50 to 200 p.s.i.a.
• the feed, with the mixture is then heated to a suflicient temperature to dissolve any wax crystals present; this temperature would approximate 110 to 200 F., preferably 140 to 180 F.
• the mixture is then sent to a feed retention drum to allow time for complete solution of all wax crystals. Following this, it is cooled to about 50 to 100 F., preferably 70 to 90 F.
• the feed is next sent to a warm solution drum from which it may be charged to batch chillers.
• the temperature is gradually dropped to about 25 to 35 F. by vaporizing at least a portion of the solvent mixture.
• propylene will be utilized so the invention will be described in terms of this particular olefin; it should be emphasized that there is no intent to exclude the other olefins mentioned in this case.
• the cooling takes place at a rate of about 1 to 15 F. per minute or an average of about 6 F./minute.
• the latter part of the autorefrigerative chilling operation is carried out at a pressure of about 10 0 to 50 p.s.i.g.
• a plurality of chillers is utilized so that while one chiller is in the chilling operation, another chiller may be emptied and filled for the next operation.
• the filter feed drum receives the chilled batches from the chiller and in turn feeds one or more rotary filters.
• the temperature at which the solution is to be filtered is indicative of an important aspect of the instant invention. Traditionally, when utilizing propane alone as a dewaxing solvent, temperatures for filtration varied between and 40 F. and this would result in oils having a pour point of +10 to 0 F. Utilizing the process of the instant invention, filtration may take place at a temperature of 25 to F. with resulting oils having a pour point of 0 to 10 F.
• the percentage of feed removed as slack wax is about 20 to 60% by weight.
• the percentage of dewaxed oil obtained will vary between and 80 wt. percent.
• the dewaxed oil passes through the filters is collected. The filtered wax and the dewaxed oil are separately heated to recover solvent therefrom.
• the hydrocarbon fraction which may be treated by this process to produce an improved lube oil will have a boiling range with an initial point between 650 and l 025+ F. and a final point between 750 and 1050+ F.
• a typical fraction will have an initial boiling range of 700 to 780 F. and a final boiling range of 750 to 850 F.
• Suitable sources for this hydrocarbon fraction include the following crudes: Aramco, Kuwait, Panhandle, North Louisiana, Tijuana Medium, etc.
• Pressure within the dewaxing zone will vary between 0 and 20 p.s.i.g., preferably 2 and 10 p.s.i.g.
• the chilling time in the dewaxing zone will vary between '20 and 60 minutes, preferably 40 and 50 minutes.
• lube and specialty oils may be obtained which have a pour point of 0 to 15 F.
• the cloud point of the lube oils obtained is also superior to the cloud points obtained by the existing techniques. They generally will be 5 to 10 F. higher than the pour point of 0 to -15 F. as defined above.
• this invention also presents other advantages over existing techniques. Extremely low cost is required to adapt an existing propane dewaxing plant to this process and a grass roots application of the instant process would not require significantly more expenditure than the traditional propane dewaxing plant. Additional advantages of this invention are as follows. Higher filter rates are obtained than with propane alone. The increase depends on the polar solvent used, the stock and the dilution. Lower power requirements, higher temperatures and hence less refrigeration compression for a given pour point represent other advantages. 1
• the general effectiveness of the polar additive is probably related to the stability of its charge-transfer complex with the olefin. On this basis, it may be assumed that the more stable the complex formed, the more effective the reduction in pour point. Acetone is particularly good for the purpose intended because it is readily available, cheap and forms a stable complex.
• EXAMPLE 1 In all of the following examples, the identical feedstream was utilized. This feedstream comprised a lube oil fraction having an initial boiling point of 675 to 725 F. and a final boiling point of 850 to 900 F. as well as the following characteristics outlined in Table I below.
• Crystal modifier of the type and concentration used in propane dewaxing plants was used in the filter-rate studies. This was 0.05% (or in some instances 0.1% of a filter aid consisting of condensates of chlorinated paraffins with naphthalene.
• various polar compounds were used in conjunction with propylene to determine the characteristics of the dewaxed oil which could be obtained.
• Propylene and the polar liquid in the particular quantity designated with each run comprises the additive.
• the total amount of lubricating oil was 100 grams, to this was added about 100 grams of additive comprising olefin and a polar component.
• Waxy oil, acetone and propylene were added, in that order, to the closed pressure vessel which was then heated to ensure miscibility and the contents were then cooled by scraped-surface heat exchange at a rate of about 2 F. per minute.
• Waxy oil, polar additive and propylene were added at ambient temperature to a chiller/ filter pressure vessel and heated to about 100 F.
• Th6 IeSLlltS obtained are indicated below in waxing agent comprising a c flc olefin in combination Table with acetone cooling said mixture by vaporizing at least a TABLE III.PROPYLENEIACETONE (/25) HAS AN D- portion of said dewaxing agent to a temperature level VANTAGE OVER PROPANE 0 wherein at least a portion of said wax precipitates, filtering Propylene] said wax and recovering said oil with a substantially lower Propane acetone' pour point Solvent/oil (vol.) ratio 1.5 1.5 5.
• a process for dewaxing a lubricating oil in order to lower its pour point which comprises adding a liquid dewaxing agent to said lubricating oil, said dewaxing agent comprising 63 to 75 wt. percent of an olefin selected from the group consisting of ethylene, propylene, and butylene and a polar electron acceptor selected from the group consisting of nitriles, S nitroalkanes, ketones, and mixtures thereof, in the amount of 25 to 37 wt. percent, heating said mixture to a temperature of 100 to 175 F., chilling said mixture by autorefrigerating said olefin, at a rate of 1 to 15 F. per minute until a temperature of 25 to --35 F. is attained wherein a substantial portion of the wax present is precipitated, filtering said precipitated wax from said mixture and recovering a lube oil having a substantially lower pour point.
• a liquid dewaxing agent comprising 63 to 75 wt.
• a process for dewaxing a lubricating oil in order to lower its pour point which comprises adding a liquid dewaxing agent to said lubricating oil, said dewaxing agent comprising 90 to wt. percent of an olefin selected from the group consisting of ethylene, propylene, and butylene and a polar electron acceptor comprising acetone in the amount of 10 to wt. percent, heating said mixture to a temperature of to F., chilling said mixture by autorefrigerating said olefin, at a rate of 10 to 15 F. per minute until a temperature of 25 to 35 F. is attained wherein a substantial portion of the wax present is precipitated, filtering said precipitated wax from said mixture and recovering a lube oil having a substantially lower pour point.
• a liquid dewaxing agent comprising 90 to wt. percent of an olefin selected from the group consisting of ethylene, propylene, and butylene and a polar electron accept

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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)
• Lubricants (AREA)

Applications Claiming Priority (1)

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Cited By (4)

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Citations (6)

• 1967
  • 1967-07-28 US US656697A patent/US3503870A/en not_active Expired - Lifetime
• 1968
  • 1968-07-11 GB GB33112/68A patent/GB1222417A/en not_active Expired
  • 1968-07-26 FR FR1580552D patent/FR1580552A/fr not_active Expired

Patent Citations (6)

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