Controlling biuret in urea production
AssigneeStamicarbon B.V.
InventorEelco Mostert
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Abstract
Disclosed is a novel method of controlling the formation of biuret in urea production, and particularly reducing, preventing or reversing such formation. This is accomplished by adding liquid ammonia to a urea aqueous stream. This addition is done at one or more positions downstream of a recovery section in a urea plant. The addition of liquid ammonia serves to shift the equilibrium of biuret formation from urea, to the side of the formation of urea from biuret and ammonia. The invention can be accomplished also in pre-existing urea plant, by the simple measure of providing an appropriate inlet for liquid ammonia, in fluid communication with a source of such liquid ammonia.
Claims11
A method of modernizing a pre-existing plant for the production of urea, said plant comprising a urea synthesis section having a first inlet for ammonia and carbon dioxide and an outlet for a urea aqueous solution, said outlet being in fluid communication with a recovery section having a second inlet for the urea aqueous solution, an outlet for ammonia and carbon dioxide recycle, and an outlet for a purified urea aqueous stream, said outlet for ammonia and carbon dioxide recycle being in fluid communication with a third inlet of the synthesis section, said outlet for a purified urea aqueous stream being in fluid communication with a fourth inlet of a concentration section;
- said concentration section having an outlet for steam or steam condensate, and an outlet for a concentrated urea stream, which is in fluid communication with a finishing section for the concentrated urea stream, said finishing section comprising a gas outlet in gas flow connection with an abatement section for ammonia-containing gas emissions, the modernizing method comprising:
- connecting the plant to a supply member for supplying an ammonia-comprising liquid downstream of the recovery section, through a fifth inlet connected to said supply member.
Dependencies are inferred from the claim text.