US2008286188A1PendingUtilityA1

Process for the Preparation of a Urea-Comprising Aqueous Stream

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Assignee: MEESSEN JOZEF HUBERTPriority: Mar 9, 2005Filed: Feb 24, 2006Published: Nov 20, 2008
Est. expiryMar 9, 2025(expired)· nominal 20-yr term from priority
Inventors:Jozef Hubert Meessen
Y02C20/10B01D 53/90C07C 273/16B01D 53/79B01D 53/92Y02T10/12
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Claims

Abstract

The invention relates to a process for the preparation of a urea-comprising aqueous stream, that is suitable for use in a unit for the reduction of NO x in combustion engine exhaust gases, wherein the urea-comprising aqueous stream is separated directly from or after a recovery section in a urea production process and is thereafter diluted with water until the urea-comprising stream comprises 30-35 wt % urea.

Claims

exact text as granted — not AI-modified
1 . Process for the preparation of a urea-comprising aqueous stream, that is suitable for use in a unit for the reduction of NO x  in combustion engine exhaust gases, characterized in that the urea-comprising aqueous stream is separated directly from or after a recovery section in a urea production process and is thereafter diluted with water until the urea-comprising stream comprises 30-35 wt % urea. 
     
     
         2 . Process according to  claim 1 , wherein at least one of the recovery sections comprises a dissociation unit, in which dissociation is promoted by the addition of a stripping medium, characterized in that the urea-comprising aqueous stream is separated after the dissociation unit. 
     
     
         3 . Process according to  claim 1  or  2 , characterized in that the urea-comprising aqueous stream is separated after the recovery section(s). 
     
     
         4 . Process according to any one of  claims 1 - 3 , wherein a urea storage tank is present after the recovery section(s) and, when a shaping section is present, before the shaping section, characterized in that the urea-comprising aqueous stream is separated from the urea storage tank. 
     
     
         5 . Process according to any one of  claims 1 - 4 , characterized in that the urea-comprising aqueous stream comprises 60-90 wt % urea. 
     
     
         6 . Process according to  claims 1 - 5 , characterized in that the urea-comprising aqueous stream is subjected to dissociation before or after dilution with water. 
     
     
         7 . Process according to  claim 2  or  6 , characterized in that the dissociation is preformed by steam stripping at a pressure of 0.001-0.2 MPa.

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