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
  • C10G73/00—Recovery or refining of mineral waxes, e.g. montan wax
  • C10G73/02—Recovery of petroleum waxes from hydrocarbon oils; Dewaxing of hydrocarbon oils
  • C10G73/26—Recovery of petroleum waxes from hydrocarbon oils; Dewaxing of hydrocarbon oils by flotation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D1/00—Flotation
  • B03D1/001—Flotation agents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D2203/00—Specified materials treated by the flotation agents; Specified applications
  • B03D2203/005—Fine and commodity chemicals

Definitions

• a process for the separation of waxy hydrocarbons from oils by flotation in which gas is passed upwardly through the 'oil cooled to a temperature below its cloud point is characterised in that the oil being treated contains at least a proportion of cracked material and in that the oil has a viscosity, at the separation temperature, of not more than 20 centistokes.
• the cracked material may contain compounds which exert a strong influence on the physical conditions and. allow the ready coalescence of the gas and solid phases. Whatever the theory, however, it has been found that quite small amounts of cracked material have a marked effec and that increasing the amount of cracked material does not lead to a position where the effect becomes overdominant and causes complications in another direction.
• the proportion of cracked material may thus range from 0.5 to 100% vol., preferably 2 to 907
• the cracked material may be derived from either 3,338,816 Patented Aug. 29, 196 7 material the maximum viscosity may thus be 20 centistokes decreasing to 15 when the percentage of cracked material is 2%.
• a feedstock which has too high a viscosity may be diluted with lower-boiling material preferably boiling in the kerosine boiling range.
• This can be either a straight run or cracked petroleum fraction and it has not been found necessary to use diluent materials such as the previously proposed conventional solvents used in filtration de-waxing.
• Waxy hydrocarbons can cause problems in oils boiling in the kerosine, gas oil and wax distillate range (i.e. 150 to 650 C.) and the process may be used on any of these feedstocks although with the heavier feedstocks more diluent will naturally be required to lower the viscosity. It has also been found that the presence of asphalt or other materials functioning as pour point depressants is deleterious, even in very small quantities, and their presence should thus be avoided.
• the cloud points of the oils being treated may vary over a fairly wide range and hence the flotation temperature may also vary. Likely temperatures will however be in the range 0 F. to 80 F., especially 20 F. to F.
• the cloud point of the dewaxed oil will with efficient operation be substantially equal to the temperature used.
• the amount of gas used is not critical and satisfactory results have been obtained with a ratio by volume of gas at S.T.P. to oil feedstock of as low as 0.2 and with no indication that this is a limiting ratio. Higher rates are not detrimental although they add little further benefit and a suitable range is thus from 0.1 to 10.
• Any convenient gas may be used, for example nitrogen, gases thermal or catalytical cracking and may be of any suitable boiling range within the limits of the range of fractions that can be treated.
• Preferred materials are those derived from catalytical cracking of gas oils or waxy distillates to gasoline, or the kerosine boiling-range fractions from the same process.
• the gas should naturally pass upwardly through the oil in the form of bubbles and if necessary it can be introduced into the bottom of the flotation bath through known bubblers and dispersers. It has been found, how ever, that the gas can be introduced quite simply and effectively by injecting it into the suction side of the pump feeding oil to the bath. Nevertheless, in that case, the pump discharge pressure must not be below certain limits, in order to dissolve at least part of the gas in the oil. Suitable pressures are in the range of 2 to 10 kg./cm.
• the rate of flow of the oil into and the withdrawal of dewaxed oil from the flotation zone should be adjusted to give a suitable residence time and these can readily be determined by experiment. In practice residence times of upwards of 7 hours have been found suitable.
• the cooling of the oil to a temperature below the cloud point is preferably carried out by cooling a stream of oil which is withdrawn from the bath, cooled and recycled, which method of cooling is described and claimed in Belgian application No. 43,901. This application also gives details of a suitable apparatus for carrying out the present process.
• Example 1 The following example compares the effect of different viscosities on the ease of Wax removal by flotation.
• the feedstock used had the following inspection data:
• Oil viscosity 50 20 10 Yield of Wax 15 20 Yield of dewaxed oil 85 80 80 80 Properties of dewaxed oil Cloud point, F 78 40 30 30 Pour point, F 70 35 25 It will be seen that satisfactory results were only obtained at viscosities of 15 and 10 centistokes and that there is a marked change in the results when altering the viscosity through the relatively small range of 20 to 15 centistokes.
• Example 2 This example compares the effect of diflerent amounts of catalytically cracked material on the ease of wax removal by flotation.
• Blend Straight run material percent vol 100 96 0 Cat. cracked material, percent vol 0 4 70 100 Cloud point, F 54 54 62 62 Pour Point, F 50 50 60 50 Viscosity at 32 F., cs 14 14 13 12 Sulphur, percent wt 1. 4 14. 1.6 1. 7
• the straight run matenals were obtained by distillation of Kuwait crude oil.
• the conditions used for the flotation Wfi j 4 Temperature of oil F 30 'Oil feed rate m. /h 10 Gas feed rate Nm. /h 5 Recycle oil rate -m. /h 200 Residence time hrs 40
• the gas used was flue gas which was injected into the suction side of the oil feed pump.
• a process for the flotation separation of waxy hydrocarbons from waxy oils to produce dewaxed oil having reduced cloud and pour points which comprises passing a flotation gas upwardly through the waxy oil which has been cooled to a temperature below its cloud point, said waxy oil containing a proportion of cracked material from 0.5 to volume and having a viscosity, at the separation temperature, of not more than 20 centistokes with the maximum viscosity range being 20* centistokes when using 100% of cracked material to 15 centistokes with 2% cracked material; said gas treatment producing a wax-containing foam layer and a dewaxed oil layer, and separating the dewaxed oil layer therefrom having reduced cloud and pour points.
• a process as claimed in claim 1 wherein the cracked material is the product of a catalytic cracking process.

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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)
• Polyesters Or Polycarbonates (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=3864823

Family Applications (1)

Country Status (9)

Cited By (1)

Citations (5)

• 1964
  • 1964-08-21 BE BE652105D patent/BE652105A/xx unknown
• 1965
  • 1965-02-05 GB GB5083/65A patent/GB1022429A/en not_active Expired
  • 1965-02-16 US US433180A patent/US3338816A/en not_active Expired - Lifetime
  • 1965-02-18 DE DE19651545346 patent/DE1545346A1/de active Pending
  • 1965-02-18 FR FR6125A patent/FR1424938A/fr not_active Expired
  • 1965-02-18 NO NO156833A patent/NO115406B/no unknown
  • 1965-02-19 DK DK87365AA patent/DK111629C/da active
  • 1965-02-19 NL NL656502143A patent/NL143981B/xx unknown
  • 1965-02-19 CH CH235865A patent/CH478221A/de not_active IP Right Cessation

Patent Citations (5)

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