US1963498A - Dewaxing hydrocarbon oils - Google Patents

Description

June 19, 1934.

Filed Aug. l. 1951 Gara/Ike, /feroueae/ Mapa, 6a.: OIZ Fit'.

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am; ATTORNEYS Patented June 19, 1934 DEWAXING HYDRoCARBoN olLs George Rf. Lord, Pelham Manon N. Y., assignor to Sinclair Refining Company, New York, NV.`Y.','`

a corporation of VMaine Application August' 1, 1931 Vserai N0.,554,49

sciaims. (01.196-,7-19) A This invention relates to improvements in the manufacture of lubricating oils. Morerparticu'- larly the invention relates to improvements in the separation of crystalline Awax andv amorphous wax, or petrolatum, from lubricating oil stocks to produce lubricatingoils containing aiminimum of wax and at the same time to effect aV sharp separation between crystalline wax and rpetrolatum. n

Crystalline wax is conventionally separated from lubricating oil stocks by chilling the stock and pressing the chilled stock, and petrolatum is conventionally separated from lubricating oil stocks by chilling the stock and centrifuging the chilled stock with an added diluent stock. The conventional pressing operation does not separate amorphous wax and thepresence of substantial quantities of crystalline wax interferes with the conventional centrifuging operation.

According to the present invention the pressingoperation and thecentrifuging operation are combined in a particularly advantageous manner to accomplish dewaxing of the 'lubricating oil stock and at the same time sharp separation of the crystalline Wax and petrolatum separated from the lubricating oil stock. Aslapplied to a Wax bearing distillate lubricating oil stock containing crystalline wax, parain distillate for example, and to a separate wax bearing lubricating oil stock from which a major portion of crystalline wax has been distilled, long residuum or 'cylinder stock for example, the first mentioned stock is chilled and pressed to separate a major portion of crystalline Wax, this pressed stock is blended with the second mentioned stock and the blended stock is chilled and centrifuged to separate amorphous Wax. As applied to a lubricating oil stock containing crystalline and amorphous wax, reduced crude for example, the stock is subjjected to distillation to separate a fraction containing a major portion of the crystalline wax and a fraction containing amorphous Wax, the first mentioned fraction is chilled and pressed to separate crystalline wax, this pressed fraction is blended with the second mentioned fraction and the blended fractions are chilled and centrifuged to separate amorphous wax. If the amorphous wax separated in the centrifuging operation includes any substantial portion of crystalline wax, this amorphous wax mixture is subjected to distillation to separate from the amorphous wax a fraction containing the included crystalline wax. This thus separated crystalline wax is advantageously combined with the lubricating oil stock `isubjected to chilling and pressing.

vThe accompanying drawing represents, as a flowsheet, one advantageous scheme of operation embodying the invention'.- The severall component operations which together constitute the combined operationV of the invention are notgconsidered severally, novel and therefore do not need to be illustrated or described in detail. Each of the several steps may be carried out in the conventional manner and in conventional'apparatus.

In the scheme of operation illustrated in the drawing, crude petroleum, a paraiin base or a mixed base crude petroleum, is subjected to distillation to separate lighter oils, gasoline, kerosene, naphtha, gas oil, etc., and the thus reduced crude oil is subjected to distillation, under conditions inhibiting decomposition', to separate a fraction containing a major portion of the crystalline wax, paraffin distillate, vfrom a Vfraction containing amorphous wax. The fraction containing amorphous wax and relatively free from crystalline wax maybe a distillatefraction .or a residual fraction. The fraction containing a major portion of the crystalline Wax ischilled and pressed to separate-amajor portion of crystalline waX. The pressed fraction is blended with the fraction containing amorphous wax and relative- Yly free from crystalline wax, these blended fractions are" chilled and centrifuged to separate amorphous wax, and the centrifuged fractions are subjected to distillation, under conditions inhibiting decomposition, to separate the desired finished lubricating oils. The separated amorphous Wax is advantageously subjected to distillation to separate a fraction containing any included crystalline wax, this fraction being cornbined with the fraction subjected to chilling and pressing to separate crystalline wax. Y A

The scheme of operation illustrated in the accompanying drawing includes a refining treatment. The character of this refining treatment may vary widely, it may consist of one or several refining treatments, and the one or several refining treatments may be embodied in the scheme of operation in various ways. In operations in which no substantial portion of diluent stock is required in the chilling and pressing operation, the refining treatment is advantageously embodied in the scheme of operation as illustrated. As applied to stocks derived from paraffin base crude petroleums, the refining treatment may consist of digestion of the blended stocks at elevated temperature with an absorbent earth or clay followed by separation of the earth or clay at lower temperature, any diluent stock required in the subsequent centrifuging operation advantageously being added following the digestion to assist in the subsequent separation of the earth or clay. As applied to stocks derived from mixed base crude petroleums, such relining treatment may be preceded by conventional treatment with sulphuric acid. In operations in which some substantial portion of diluent stock is required in the chilling and pressing operation, the added diluent stock is advantageously separated, by distillation, from the pressed stock if the pressed stock is blended with the stock containing amorphous wax and relatively free from crystalline wax and the blend then subjected to a refining treatment such as just described. Instead of separating such diluent stock, the pressed stock mixture including the diluent may be blended with the stock containing amorphous Wax and relatively free from crystalline wax following a rening treatment such as that just described, and prior to subsequent chilling and centrifuging. The lubricating oils produced may be iinished, for example, by percolation through an absorbent earth or clay. The particular character of the refining treatment and particular manner in which it is embodied in the general scheme of operation is not part of this invention and the invention is not to be limited to the foregoing examples of the rening treatments which may be used.

In the chilling and pressing operation, ythe separation of wax may be carried to a point, for example, such that the pressed stock has a pour test of 1li-20 F. The stock mixture supplied to the centrifuging operation may comprise, forexample, 5-20 parts (by volume) of the pressed stock and -35 parts of the stock containing amorphous wax and relatively free from crystalline wax together with -150 parts of a diluent stock, naphtha for example. In the chilling and centrifuging operation the separation of wax may be carried to that point required to produce finished lubricating oils having the desired pour test, 0 F. or lower for example.

In the scheme of operation illustrated in the accompanying drawing the stock containing a major portion of crystalline wax and stock containing amorphous wax and relatively free from crystalline wax are derived from one original stock. It will be apparent that the invention is applicable also to the combined handling of a stock containing a major portion of crystalline wax and a stock containing amorphous wax and relatively free from crystalline wax derived from separate sources.

In carrying out the present invention, crystalline wax is separated in the chilling and pressing operation, an operation well adapted to the separation of crystalline Wax, and petrolatum, or amorphous wax, is separated in the chilling and centrifuging operation fromV a blended stock relatively free from crystalline wax. Eiective dewaxing of the lubricating oil stock is thus accomplished. At the same time, a sharp separation of the separated crystalline wax and petrolatum is also accomplished. The value of each of the products of the operation is thus enhanced.

I claim:

1. In the manufacture of lubricating oils, the improvement which comprises chilling and pressing a Wax-bearing distillate lubricating oil stock to separate a major portion of crystalline wax, blending this pressed stock with a wax-bearing lubricating oil stock from which a major portion of crystalline wax has been distilled, and chilling and centrifuging this blended stock to separate amorphous wax.

2. In the manufacture of lubricating oils, the 10() improvement which comprises subjecting a lubricating oil stock containing crystalline and amorphous wax to distillation to separate a fraction containing a major portion of the crystalline wax and a fraction containing amorphous 105 wax, chilling and pressing the rst-mentioned fraction to separate crystalline wax, blending this pressed fraction with the second-mentioned fraction, and chilling and centrifuging the blended fractions to separate amorphous wax.

3. In the manufacture of lubricating oils, the improvement which comprises chilling and pressing a Wax-bearing distillate lubricating oil stock to separate a major portion of crystalline wax, blending this pressed stock with a wax-bearing 115 lubricating oil stock from which a major portion of crystalline wax has been distilled, chilling and centrifuging this blended stock to separate amorphous wax, subjecting the separated amorphous wax to distillation to separate a 120 fraction containing crystalline wax included in the separated amorphous wax and combining this separated fraction with the nist-mentioned wax-bearing distillate lubricating oil stock prior to chilling and pressing.

GEORGE R.. LORD.

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