Stamicarbon B.v.

Dsm IP Assets B.v.

Eelco Mostert

Johan Albert Arno Van Den Tillaart

Joannes Albertus Wilhelmus Lemmens

Rita Dimphina Joosten

Joseph Johannes Gerardus Bindels

A urea plant and urea production process of the stripping type are provided that are adapted for making Diesel Exhaust Fluid (DEF) or precursor thereof in a DEF production unit downstream of a treatment section. The treatment section receives a part of the urea synthesis stream from a reaction zone, in particular bypassing the HP stripper.

Stripping-type urea plant for def production

Disclosed is a novel method of controlling the formation of biuret in urea production. This is accomplished by reducing or preventing the formation of biuret in a concentration section, particularly in one or more concentrators or evaporators. The method comprises controlling the residence time of a urea aqueous stream treated in such concentration section in a manner independently of the volume flow per time interval of said stream into said concentration section. The residence time can be controlled, e.g., by providing the concentration section with an adjustable volume or by adding a gas to the urea stream to be treated. A combination of such measures can also be applied.

Urea production with controlled biuret

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.

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Sittard, Netherlands

Eelco Mostert