Patent ID: 8263802

Claim:
A process for redissociating Michael adducts which have been formed in the preparation of acrylic acid or esters thereof, comprising: feeding a liquid F having a temperature T Z to a separating column K at a Feed Point I in a separating space of the column above a lowest separating internal; separating the liquid F into at least a gas stream G comprising at least one of acrylic acid and an ester thereof as Michael addition redissociation products and a reflux liquid; removing the gas stream G from a top space of the column K; collecting the reflux liquid having a temperature T SU in a bottom space of the column K having a gas pressure GD to form a bottom liquid having a liquid level S; removing a stream {dot over (M)} from the bottom space of the column K; pumping the stream {dot over (M)} at T SU via a radial centrifugal pump P having a semiopen radial impeller through a secondary space of an indirect heat exchanger UW; heating the stream {dot over (M)} in the heat exchanger UW to form a stream {dot over (M)}* having a temperature T RS ; feeding the stream {dot over (M)}* to a Feed Point II in the bottom space of the column K; wherein a proportion of Michael addition product in the liquid F, is at least 10% by weight based on the weight of the liquid F, a pressure of the gas phase in the column K decreases from the bottom upward, the temperature T RS is greater than T SU and is such that at least a portion of the Michael adducts present in stream {dot over (M)}* is redissociated to form the at least one of acrylic acid and an ester thereof as Michael addition redissociation products; the Feed Point II is located below the lowermost separating internal of the separating column K and above the level S of the bottoms liquid, the level S is less than half a distance A measured from a lowest point of the column K to an underside of the lowermost separating internal, stream {dot over (M)}* is fed at Feed Point II in such a way that the feed stream is not directed toward the bottoms liquid; and the stream {dot over (M)}* boils at the gas pressure GD.