Method for concentrating an aqueous ammonium carbamate stream

Details Method for concentrating an aqueous ammonium carbamate stream Method for concentrating an aqueous ammonium carbamate stream

2011-02-22

2011-02-22

Sullivan, Daniel M (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Carboxylic acids and salts thereof

C562S550000

Reexamination Certificate

active

07893298

ABSTRACT:
The invention relates to a method for concentrating an aqueous ammonium carbamate stream, which has been formed in a process for the preparation of urea, has a pressure between 0.20 MPa and 0.9 MPa, a temperature between 35° C. and 95° C., and contains at least 25 wt. % H2O, comprising: a pressure increase step, in which the aqueous ammonium carbamate stream is increased in pressure to a pressure between 1.0 MPa and 7 MPa; a condensation step, in which the aqueous ammonium carbamate stream is contacted with a gas stream, which has been formed in a process for the preparation of melamine and which consists essentially of NH3, CO2and optionally H2O and has a lower H2O content than the aqueous ammonium carbamate stream, the gas stream being absorbed in the aqueous ammonium carbamate stream in such a way that a concentrated ammonium carbamate stream is formed that contains between 15 and 35 wt. % H2O; a discharge step, in which the concentrated ammonium carbamate stream is separated and discharged.

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Badische Anilin & soda-Fabrik AG, Supply of Waste Gas for Ureau Synthesis—using contrlled ammonia to carbon dioxide ratio, 1972, DE 2053358 (A1) English translation, 5 pages.
International Search Report mailed Jul. 27, 2006 in PCT/NL2006/000249.

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