Process for the purification of urea solutions containing biuret and the like

Abstract

Disclosed is a process and apparatus for purifying and regenerating urea solutions which have been contaminated with biuret and triuret and the like during the use of the urea solutions such as in dewaxing processes. The contaminated urea solution is first contacted with ammonia in gaseous or liquid form and about one to ten percent of the ammonia is absorbed into the contaminated solution. The contaminated solution and absorbed ammonia are reacted in a reactor with heating for a period of time sufficient to complete the reaction of biuret and triuret to produce urea. The purified product solution may then be returned for further use in dewaxing processes. Excess ammonia and CO.sub.2 formed during the reaction process by the decomposition of urea may optionally be separated from the purified solution and from each other with the separated excess ammonia being returned to the absorber for reuse.

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