Method and apparatus for purifying acrylic acid, and acrylic acid purified by the method
AssigneeSulzer Chemtech AG
InventorsKurt Saxer, Ralph Stadler
Life of this patent
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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.
Claims15
A method of purifying acrylic acid by fractional crystallization comprising 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;
- wherein acrylic acid containing up to 20% by weight of impurities, is supplied to the dynamic crystallization stage and the acrylic acid is purified in two or more stages by crystallization/melting cycles in a dynamic crystallizer, the crystallized material from the highest stage being recovered as the purified acrylic acid, and in the lowest stage of dynamic crystallization the impurities in the residue are concentrated to up to about 30%, the residue being subjected to the static crystallization, in which the residue is purified in at least one stage, whereby the impurities in waste leaving the static crystallization of the purification process can be concentrated to up to about 70% by weight, and the crystallized material acrylic acid enriched fraction from the highest stage of the static crystallization is recycled to the dynamic crystallization stage;
- and
- wherein the dynamic crystallization is of the falling-film or fully flowed-through tube type.
A method of purifying acrylic acid by fractional crystallization, wherein acrylic acid is purified by a combination of suspension crystallization and static crystallization in a number of stages, the residue from suspension crystallization being further purified by static crystallization and the resulting enriched acrylic acid being returned to suspension crystallization;
- and
- wherein acrylic acid containing up to 20% by weight of impurities is supplied to a suspension crystallization stage and the acrylic acid is purified in one or more stages in crystallization/melt cycles, the crystallized material from the highest stage leaving the purification process, and in the lowest stage of suspension crystallization the impurities in the residue are concentrated to up to about 30%, the residue serving as a feed for static crystallization, in which the residue is purified in at least one stage whereby the impurities in the residue leaving the purification process can be concentrated to up to about 70% by weight and the crystallized material obtained from the highest stage of static crystallization is returned to dynamic crystallization.
Dependencies are inferred from the claim text.