Sulzer Chemtech Ag

Schumann Sasol Gmbh & Co. Kg

Herbert Engstler

Florian Lippuner

Manfred Stepanski

Ferdinand Richter

Andrzej Kuszlik

Norbert Matzat

Bernhard J Jans

Gunther Hildebrand

Matthias Schäfer

Matthias Schaefer

A process and an apparatus for the purification of a crude acrylic acid composition containing maleic anhydride as an impurity comprising the following steps: (a) carrying out at least one dynamic melt crystallization stage () with the crude acrylic acid composition to prepare a first purified acrylic acid composition and a first residue containing at least 3.5% by weight maleic anhydride, (b) adding a solvent () which is capable of dissolving maleic anhydride to the first residue in an amount that the weight ratio of the solvent to the maleic anhydride is 0.3 or more to prepare a ratio-adjusted residue and (c) carrying out at least one further dynamic melt crystallization stage and/or at least one static melt crystallization stage () with the ratio-adjusted residue to prepare a second purified acrylic acid composition and a second residue.

Process and apparatus for purification of acrylic acid

A process for fractional crystallization of paraffin from mineral oil based and synthetic crude paraffin, wherein crude paraffin having a high oil content is crystallized in a crystallizer equipped with perforated metal sheets (31) extending in a zig-zag in the spaces between the heat exchanger surfaces (39). The paraffin-containing melt is only solidified to an extent such that the fractions and oils for discharge remain liquid and are run off without total solidification of the melt. The perforated sheets (31) support the layers of crystals (43) and during sweating the paraffin is detached in strips from the heat exchanger surface (39) and is adapted to rest on the sloping perforated sheets (31). The inclination of the perforated sheets (31) guides and moves the paraffin strips (53), so that the paraffin strips remain in contact with the heat exchanger surfaces (39) while being pressed by their own weight along the inclined surface (30) towards the heat exchanger surfaces (39).

Process for obtaining paraffin or paraffin fractions

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Frastanz, Austria

Herbert Engstler