US2889260A - Process for the dewaxing of oils - Google Patents

Process for the dewaxing of oils Download PDF

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US2889260A
US2889260A US54822755A US2889260A US 2889260 A US2889260 A US 2889260A US 54822755 A US54822755 A US 54822755A US 2889260 A US2889260 A US 2889260A
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oil
urea
adduct
stage
conduit
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    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10GCRACKING 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
    • C10G73/00Recovery or refining of mineral waxes, e.g. montan wax
    • C10G73/02Recovery of petroleum waxes from hydrocarbon oils; Dewaxing of hydrocarbon oils
    • C10G73/24Recovery of petroleum waxes from hydrocarbon oils; Dewaxing of hydrocarbon oils by formation of adducts

Definitions

  • urea forms solid compounds or adducts with straight-chain parain hydrocarbons.
  • Derivatives of the straight-chain parailins for instance olens, oxygen, nitrogen, sulfur and halogencontaining substances, will similarly enter into this rreaction with urea, provided that they do not contain long side chains.
  • urea CO(NH2)2 forms adducts with straight; chain paratiins and their derivatives
  • thiourea CS(NH2)2 forms adducts with branched-chain parains and naphthenes under conditions similar to those for adduct formation between urea and n-parains.
  • the liquid paraiiins or their derivatives are brought into contact with urea; the solid adduct produced is separated from the nonadduct forming substances and (1) by heating to elevated temperatures or (2) by the addition of solvents is reconverted into parafns on the one hand and (1) the urea or (2) a solution thereof on the other hand.
  • the temperature of the adduct formation depends upon the size of the molecules of the hydrocarbons and is generally between -lO and +50 C.
  • the quantity of urea to be used also diiers; it increases with the length of the chains and is an average of 3 parts by weight of urea. to l part by weight of paraiiin.
  • the commencement and duration of the adduct formation is activated by the presence of solvents for the urea.
  • solvents for the urea there may be used water and/ or water-miscible solvents, e.g. lower alcohols such as methanol and ethanol, ketones such as acetone, and the like.
  • the quantity of the solvent, the so-called activator varies within wide limits since the urea may lbe used as a saturated or supersaturated solution or as a paste wetted with solvent. Viscous and parain-rich oils are diluted with solvents which have a good dissolving power for the oil to be treatedbut not for the adductsuch as benzene, naphtha, organic halogen compounds, and the like.
  • the removal of paraiflns or dewaxing embraces both the formation of an adduct of urea with n-parains or their derivatives, and of thiourea with isoparains, naphthenes or their derivatives.
  • the speed with which the adduct is formed, as. well as the quantity of paraffin taken up through formation of the adduct, is also dependent upon the quantity of the adduct former available. Assuming that it is desired to remove a predetermined amount of paraiinic hydrocarbons or waxes from an oil to bring the pour point to a predetermined value, there would be employed three times as much urea by weight as contrasted with the parafln. Completion of ⁇ the reaction would require ICC extremely long contact periods which would make a continuous process impractical.
  • urea or thiourea is contacted with the paraffincontaining oil in stages, i.e., in the first stage untreated oil is contacted with an adduct still containing some unco-mbined urea.
  • the pre-treated oil is contacted with fresh urea or regenerated urea respectively, the products constituting the oil of desired pour point and an adduct phase containing uncornbined urea which is sent to the rst stage for reaction With fresh oil.
  • Figure 1 is a How-sheet of a process conducted without temperature control
  • Figure 2 is a How-sheet of a modied process conducted with individual temperature control during the separate stages of the reaction.
  • an adduct of urea with straight-chain parans or their ⁇ derivatives and containing unreacted urea is passed from iilter 10 through conduit 11 into mixer 12.
  • Fresh oil, containing straight-chain paraflinic waxes which it is desired to remove, is introduced through conduit 13 into the mixer 12 where -it is permitted to contact the unreacted urea carried along with the adduct and introduced through conduit 11.
  • the paraiinic'com-r pounds having the greatest alinity ⁇ for the urea f0r ⁇ 11i- 3 adducts with the urea until the urea is completely exhausted through adduct formation.
  • the suspension of adduct and oil still containing some parainic materials is passed through conduit 14 into a centrifuge 15 where the oil is separated vfrom the solid adduct.
  • the adduct is preferably passed through washer 16 and' then to the decomposer 17 where upon addition of urea solvent through conduit 27 it is broken down into paratiinic Wax and urea solution.
  • the parathnic wax is removed from the system through conduit 20.
  • the urea solution is drawn ofi through conduit 19 and is transferred to a thickener 26.
  • the excess of urea solvent is evaporated, condensed and recycled to the ⁇ decomposer 17 through conduit 27.
  • the urea solution, regenerated in the thickener 26 is admitted into mixer 21 through conduit 28, pre-treated oil from centrifuge 15 also being admitted into mixer 21 through conduit 22. From the mixer 1 the slurry of adduct and oil solution then passes via conduit 23 to the filter 10. The adduct which precipitated as a solid ⁇ is separated from the solution of dewaxed oil and oil solvent, the adduct being recycled through conduit 11.
  • the solution of oil and oil solvent introduced in the evaporating system 24 is heated to evaporate the oil solvent by means of an evaporator 24 and the finished oil is pumped into a storage Vessel or tank 25. The evaporated oil solvent is condensed and recycled through conduit 18 to the washer 16. The wash-iiltrate containing some oil is recycled through conduit 29 into the mixer 12.
  • the quantity of urea passing through the system per cycle is that calculated to react with the paranic waxes whose removal is desired, ie., three times the weight thereof.
  • this can be compensated lfor by changing the rate of introduction of fresh oil and hence of paraftlnic waxes, or preferably it is compensated for by either adding further quantities of urea or by removing a portion of the urea solution formed in the decomposer 17.
  • the process is equally elective using urea for the separation of straight-chain paraiiins and their essentially straight-chain derivatives, or using thiourea for the separation of branched-chain parains or naphthenes and their derivatives. If desired, heat can be employed to effect the decomposition of the adduct in decomposer 17.
  • the process may also be etlected in a multistage countercurrent operation wherein temperature con-trois are provided, as shown in Fig. 2.
  • Adduct containing excess urea is introduced from conduit 26 into mixer 27 and there stirred with fresh oil introduced through con- I duit 28, the fresh oil containing straight-chain paraffnic waxes which it is desired to remove.
  • the contents of the mixer 27 are cooled by evaporation of solvent from the mixer, evaporation being eiected by pump 29 which draws ott solvent vapors via conduit 30 and introduces the vapors into conduit 37.
  • the paraffin components exhibiting the greatest ainity for the urea react with the urea until the urea is fully exhausted, the reaction occurring substantially instantaneously.
  • the slurry consisting of adduct and oil solution is conducted Via conduit 31 into centrifuge 32 where it is separated into solid adduct and oil, the adduct leaving through conduit 33 while the oil leaves through conduit 34.
  • the adduct is washed in washer 35 and then passes to decomposer 36, in which the adduct is decomposed to paraftinic wax and urea solution.
  • the parainic wax is withdrawn through conduit 38.
  • the urea solution however, is passed through conduit 39 into thickener 50, where the excessive urea solvent is evaporated, condensed and then recycled through conduit 51 to the decomposer 36, while the regenerated urea solution passes to the mixer 45 through conduit 52.
  • Theoil leaving the centrifuge 32 through conduit 34 passes into a second mixer 40 Where it is reacted with adduct, containing, more urea, than in the firstv stage, this .4. adduct being introduced through conduit 41.
  • the remaining parains react with the urea and the slurry is passed through conduit 42 into centrifuge 43.
  • the adduct together with urea and some solvent is separated and returned through conduit 26 to the rst mixer 27.
  • the oil passes oi through conduit 44 into the third mixer 45 which is also supplied with the regenerate-d urea solution through conduit 52 leading from the thickener 50.
  • the slurry passes through conduit 46 into iilter 47.
  • the adduct plus urea which is filtered ott together with some adherent urea solvent is passed to the secon-d stage through conduit 41 while the dewaxed oil together with the major portion of the oil solvent pass into evaporator 48 wherein the solvent is distilled oit and returned to conduit 37 for use in the washer 35.
  • the oil is then passed tothe tank 49.
  • the Wash-ltrate containing some oil is passed through conduit 53 to the mixer 27 in order to dilute the fresh oil.
  • Example I In a typical run employing the apparatus of Fig. 1, urea was employed for dewaxing a spindle oil of Kuwaitv origin containing 9.5% by weight of parafins. To bring the oil to the desired pour point, it was necessary to remove about grams of paratn wax per liter of oil. The system was operated at a rate such that 30 grams of urea dissolved in water were discharged from the thickener per second. The feed rate was therefore adjusted to 0.11 liters per second, i.e., substantially 3 grams of urea being recycled for each gram of paraffin Wax introduced. The paratiin wax was removed in the desired amount when running the apparatus over a period of one hour. The pour point of the raliinate was 20 C.
  • Example II The apparatus of Fig. 2 was fed with an oil containing branched-chain paraiiins. To obtain the desired pour point it was necessary to remove 18 grams of wax per liter of oil. The process was conducted with thiourea, the regeneration rate of thiourea in the thickener amounting to 30 grams per second, dissolved in Water. The feed rate of the oil was therefore adjusted to .55 liter per second. The temperature of the slurry leaving thefirst mixer was 10 C., the temperature leaving the second mixer was 18 C., and the temperature leaving the third mixer was 23 C. The calculated amount of .parathn was recovered per unit of time, the dewaxed oil exhibiting the desired pour point.
  • the process for the dewaxing of oils comprising the steps of treating an oil in successive stages with a material selected from the group consisting or urea and thiourea at temperatures of between about C. and about +50 C., and employing in the last stage a fresh quantity of said material in substantially the amount necessary to remove the desired quantity of paranic waxes from the fresh oil introduced in the first stage, said material forming an adduct with some of said parainic waxes in each stage, separating the oil from the 'adduct and any unreacted material in each stage, said adduct in all stages except the first containing unreacted material, passing said adduct with unreacted material in each stage except the rst stage to the preceding stage there to be used for dewaxing of the oil, removing the oil dewaxed to the desired degree from the last stage, and removing the adduct from the first stage.
  • a material selected from the group consisting or urea and thiourea at temperatures of between about

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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)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
US54822755 1954-11-27 1955-11-21 Process for the dewaxing of oils Expired - Lifetime US2889260A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEE9888A DE957328C (de) 1954-11-27 1954-11-27 Verfahren zur kontinuierlichen Abtrennung von Paraffinen aus Kohlenwasserstoffoelen durch Adduktbildung

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US2889260A true US2889260A (en) 1959-06-02

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US (1) US2889260A (de)
DE (1) DE957328C (de)
FR (1) FR1135712A (de)
GB (1) GB826942A (de)
NL (1) NL98678C (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4504376A (en) * 1984-04-09 1985-03-12 Texaco Inc. Urea dewaxing of naphthene oils

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1107362B (de) * 1956-07-21 1961-05-25 Scholven Chemie Ag Verfahren zur Herstellung eines nicht backenden, feinkoernigen Adduktes aus Kohlenwasserstoffen und Harnstoff

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2499820A (en) * 1947-02-21 1950-03-07 Thiourea-hydrocarbon complexes
US2695283A (en) * 1954-11-23 Method of forming urea and tfflourea
US2723220A (en) * 1950-04-10 1955-11-08 Phillips Petroleum Co Dewaxing of lubricating oil

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2695283A (en) * 1954-11-23 Method of forming urea and tfflourea
US2499820A (en) * 1947-02-21 1950-03-07 Thiourea-hydrocarbon complexes
US2723220A (en) * 1950-04-10 1955-11-08 Phillips Petroleum Co Dewaxing of lubricating oil

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4504376A (en) * 1984-04-09 1985-03-12 Texaco Inc. Urea dewaxing of naphthene oils

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DE957328C (de) 1957-01-31
FR1135712A (fr) 1957-05-03
GB826942A (en) 1960-01-27
NL98678C (de) 1961-08-15

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