Method and apparatus for purifying a mixture comprising oil and wax

Patent metadata

Field	Value
Publication number	US-10738248-B2
Application number	US-201716082131-A
Country	US
Kind code	B2
Filing date	Aug 31, 2017
Priority date	Dec 9, 2016
Publication date	Aug 11, 2020
Grant date	Aug 11, 2020

Abstract

The present invention relates to a method for fractionating a crude mixture comprising at least one oil and at least one wax, which comprises the following method steps: (a) carrying out a pre-fractionation stage as a layer crystallization (i) with a crude mixture comprising at least one oil and at least one wax or (ii) with a crude solvent mixture obtained by adding prior to the pre-fractionation stage at most 100% by weight of solvent relative to the weight of the crude mixture, to prepare a first fraction containing low waxy oil and a second fraction containing low oily wax, (b) carrying out a first crystallization stage including (b 1 ) a first suspension crystallization sub-stage with the first fraction containing low waxy oil to prepare a third fraction containing dewaxed oil and a fourth fraction and (b 2 ) after the first suspension crystallization sub-stage, a second suspension crystallization sub-stage with a mixture of the fourth fraction obtained in method step (b 1 ) and the second fraction containing low oily wax obtained in the pre-fractionation stage of method step (a) to prepare a fifth fraction containing slack wax and a sixth fraction.

First claim

The invention claimed is:

1. A method for fractionating a crude mixture comprising at least one oil and at least one wax, the method comprising the steps of:
(a) performing a pre-fractionation step ( 2 ) as a layer crystallization (i) with a crude mixture comprising the at least one oil and the at least one wax or (ii) with a crude solvent mixture obtained by adding prior to the pre-fractionation step ( 2 ) at most 100% by weight of solvent relative to the weight of the crude mixture, wherein the pre-faction step ( 2 ) is sufficient to prepare a first fraction containing low waxy oil and a second fraction containing low oily wax,
(b) preforming a first crystallization step ( 12 ) which includes the further sub-steps of:
(b 1 ) performing a first suspension crystallization sub-step ( 14 ) with the first fraction containing low waxy oil to prepare a third fraction containing dewaxed oil and a fourth fraction; and
(b 2 ) after the first suspension crystallization sub-step ( 14 ), performing a second suspension crystallization sub-stage ( 14 ′) with a mixture of the fourth fraction obtained in the pre-fractionation stage of method sub-step (b 1 ) and the second fraction containing low oily wax obtained in step (a) to prepare a fifth fraction containing slack wax and a sixth fraction.

2. The method in accordance with claim 1 , wherein the pre-fractionation stage ( 2 ) comprises one or more layer crystallization sub-stages performed each with one or more static crystallizers.

3. The method in accordance with claim 1 , wherein the layer crystallization of the pre-fractionation stage ( 2 ) of method step (a) is carried out so that the first fraction obtained after crystallization comprises at most 70% by weight of the wax content of the crude mixture.

4. The method in accordance with claim 1 , wherein the method further comprises
(c) carrying out a second crystallization stage ( 36 ) comprising:
(c 1 ) carrying out at least one crystallization sub-stage ( 38 , 38 ′) with at least a part of the fifth fraction obtained in method step (b 2 ), wherein to the fifth fraction prior to the crystallization in method step (c 1 ) no solvent or at most 100% by weight of solvent relative to the weight of the fifth fraction are added, to prepare a seventh fraction containing deoiled light wax having an oil content of at most 5% by weight and having a kinematic viscosity of at most 7 cSt and an eighth fraction containing light soft wax having an oil content of more than 5% by weight and a kinematic viscosity of at most 7 cSt and
(c 2 ) optionally circulating at least a part of the eighth fraction into the second crystallization sub-stage ( 14 ′) of the first crystallization stage ( 12 ) of method step (b 2 ).

5. The method in accordance with claim 4 , wherein the method further comprises
(d) carrying out a third crystallization stage ( 43 ) comprising:
(d 1 ) carrying out at least one crystallization sub-stage ( 14 ″, 14 ″) with at least a part of the fifth fraction obtained in method step (b 2 ), wherein to the fifth fraction prior to the crystallization in method step (c 1 ) more than 100% by weight of solvent relative to the weight of the fifth fraction are added, to prepare a ninth fraction containing deoiled heavy wax having an oil content of at most 5% by weight and a kinematic viscosity of more than 7 cSt and a tenth fraction containing heavy soft wax having an oil content of more than 5% by weight and a kinematic viscosity of more than 7 cSt.

6. The method in accordance with claim 5 , wherein the crude mixture is mixed in any of method steps (a), (c 1 ) and (d 1 ) with a solvent selected from the group consisting of methyl ethyl ketone, methyl isobutyl ketone, acetone, benzene, toluene, dichloroethane, methylene dichloride, methanol, methyl tertiary butyl ether, N-methyl-pyrolidone and mixtures of two or more of the aforementioned solvents.

7. The method in accordance with claim 4 , wherein in the second crystallization stage ( 36 ) in method step (c) at least one layer crystallization sub-stage ( 38 , 38 ′) is carried out.

8. The method in accordance with claim 4 , wherein in the second crystallization stage ( 36 ) in method step (c) one to five crystallization sub-stages ( 38 , 38 ′) are carried out.

9. The method in accordance with claim 4 , wherein in method step (c 2 ) 10 to 100% of the eighth fraction are circulated into the second crystallization sub-stage ( 14 ′) of method step (b 2 ).

10. The method in accordance with claim 1 , wherein the crude mixture includes 60 to 99% by weight of oil and 1 to 40% by weight of wax.

11. The method in accordance with claim 1 , wherein the first suspension crystallization sub-stage ( 14 ) of the first crystallization stage ( 12 ) in method step (b 1 ) and the second suspension crystallization sub-stage ( 14 ′) of the first crystallization stage ( 12 ) in method step (b 2 ) are carried out so that the third fraction containing dewaxed oil obtained in method step (b 1 ) comprise less than 5% by weight of wax and/or so that the fifth fraction containing slack wax obtained after method step (b 2 ) comprises less than 30% by weight of oil.

Assignees

• Sulzer Chemtech Ag

Inventors

• Pfeil Mathias

Classifications

• C11B7/00

  Separation of mixtures of fats or fatty oils into their constituents, e.g. saturated oils from unsaturated oils · CPC title

• C11B3/001

  by a combination of two or more of the means hereafter · CPC title

• C10G73/42

  Refining of petroleum waxes · CPC title

• C10G73/36

  Recovery of petroleum waxes from other compositions containing oil in minor proportions, from concentrates or from residues; De-oiling, sweating · CPC title

• C10G73/06

  with the use of solvents · CPC title