Abstract: A method of purifying acrylic acid by fractional crystallization is provided. The method includes the steps of subjecting an acrylic acid containing mixture to a dynamic crystallization stage to recover purified acrylic acid, leaving a residue containing acrylic acid; subjecting the residue to a static crystallization stage to recover an acrylic acid enriched fraction; and recycling the acrylic acid enriched fraction to the dynamic crystallization stage for recovery of purified acrylic acid.

Abstract: A method for separating components of a substance, for example, a fatty acid ester such as palm oil, by dissolving the substance in a solvent. The resultant solution is circulated and cooled in a circuit with crystals being formed in the solution as the temperature is lowered. The crystals are continuously separated from the circulating solution during the crystal separation phase of the process. The crystals are then preferably washed and recovered. Preferably there is a second crystallization phase in the process. The invention includes the apparatus used to carry out the process and, particularly, novel fractionating columns and filter surfaces within said columns used in the preferred embodiments of the process.

Abstract: A single or multi-step fractional crystallization process and apparatus for separating fluid material having two or more components, the material flowing down a cooled wall surface and a component crystallizing thereon. Each step comprises a single crystallization and all steps of a complete cycle are conducted within a single crystallizer.