DETAILED DESCRIPTION We claim: 1.
In a multistage process for producing urea, including a first stage for the production, from a gaseous mixture of hydrogen, nitrogen, CO.
sub.
2 and H.
sub.
2 O from steam reforming, of a mixture of hydrogen and nitrogen for use as a feed in the synthesis of ammonia, in which water in said gaseous mixture is condensed as a first aqueous condensate, said first aqueous condensate is separated from the gases therein and CO.
sub.
2 is then separated from said gases as a feed in urea synthesis, a second stage for the synthesis of ammonia from the mixture of hydrogen and nitrogen, and a third stage for the synthesis of urea from the ammonia and CO.
sub.
2 with the production of H.
sub.
2 O, the improvement consisting essentially of condensing the H.
sub.
2 O, produced in said third stage as a second aqueous condensate, mixing said first and second aqueous condensates to form a combined aqueous condensate containing impurities including ammonia, urea, carbon dioxide, nitrogen, methanol, and hydrogen, passing said combined aqueous condensate through a filter adapted to remove solids therefrom, feeding said filtered combined aqueous condensate containing said impurities to a boiler so that steam is produced therefrom, and then utilizing said steam in the steam reforming in said first stage.
2.
The process of claim 1 wherein said combined aqueous condensate also contains trace amounts of metals.
Description:
This invention relates to a method for the production of urea in which the sewage waters are reclaimed in a virtually complete way.
It is known that the following main stages are required for the production of urea, viz.
: Production of the hydrogen-nitrogen mixture to be fed to the ammonia production; Synthesis of ammonia, Synthesis of urea.
In the first of these main stages, the production of the hydrogen and nitrogen mixture, there is a section for the absorption of carbon dioxide to purify the gas which will then be sent to the ammonia synthesis.
Such an absorption section is generally formed by a CO
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