Sulzer Chemtech Ag

Sulzer Management Ag

Mathias Pfeil

Manfred Stepanski

Halbe Jansen

A process for the separation of a substance from a liquid feed mixture and for the purification of the substance by fractional layer crystallization, wherein the liquid feed mixture comprises the substance to be separated and purified in a concentration of less than 50% by weight, which comprises the subsequent steps in the given order: (a) feeding the liquid feed mixture into a crystallization zone, in which at least one surface is provided, so that at least a part of the surface contacts the liquid feed mixture, (b) cooling the at least one surface of the crystallization zone to a temperature below the equilibrium freezing temperature of the liquid feed mixture so that a crystal layer enriched in the substance to be separated and purified is deposited on the at least one cooled surface, whereby a mother liquid having a lower concentration of the substance to be separated and purified than the liquid feed mixture is formed from the liquid feed mixture, (c) removing at least a portion of the mother liquid from the crystallization zone, (d) adding a further portion of liquid feed mixture into the crystallization zone, (e) allowing further deposition of a crystal layer enriched in the substance to be separated and purified to take place on the at least one cooled surface, (f) optionally carrying out a sweating stage and removing a sweating residue and (g) melting the crystal layer to obtain the separated and purified substance.

Semi-continuous crystallization method and apparatus

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) 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) 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) 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.

Method and apparatus for purifying a mixture comprising oil and wax

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 steps: (a) mixing the crude mixture with a solvent to obtain a crude solvent-mixture, (b) carrying out at least one crystallization stage with the solvent-mixture obtained in step (a) to prepare a first fraction containing dewaxed oil and a second fraction containing slack wax, (c) carrying out at least one crystallization stage with the second fraction obtained in step (b) in a layer crystallizer, wherein to the second fraction prior to the crystallization in step (c) no solvent or at most 100% by weight of solvent relative to the weight of the second fraction are added, to prepare a third fraction containing hard wax having an oil content of at most 1.5% by weight and a fourth fraction containing soft wax having an oil content of more than 1.5% by weight and (d) circulating at least a part of the fourth fraction into at least one of the at least one crystallization stage of step (b).

A process to purify a compound comprising a suspension crystallization step and additionally comprises a layer crystallization step and a storage step of an intermediate product obtained from the layer crystallization step before to its further purification in the suspension crystallization step.

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Winterthur, Switzerland

Mathias Pfeil