Process for making ammonia and urea

An integrated process for making ammonia and urea comprises passing ammonia synthesis gas, containing carbon dioxide, nitrogen and hydrogen, into a first zone maintained under conditions to separate carbon dioxide from the synthesis gas in an ammonia-containing liquid and to obtain a condensate comprising ammonium carbamate, passing the remaining ammonia synthesis gas to an ammonia synthesis zone and passing said condensate into a second zone maintained at a pressure higher than said first zone and under urea synthesis conditions to produce urea therefrom. Alternatively, a portion of the raw ammonia synthesis gas may be passed directly to a conventional carbon dioxide purification system and the synthesis gas from which the carbon dioxide has been removed may then be passed to the ammonia synthesis zone. The ammonia synthesis may be effected by a known process and the product may be passed to the urea synthesis zone. The whole process may be effected either batchwise or continuously.ALSO:An integrated process for making ammonia and urea comprises passing ammonia synthesis gas, containing carbon dioxide, nitrogen and hydrogen, into a first zone maintained under conditions to separate carbon dioxide from the synthesis gas in an ammonia-containing liquid and to obtain a condensate comprising ammonium carbamate, passing the remaining ammonia synthesis gas to an ammonia synthesis zone and passing said condensate into a second zone maintained at a pressure higher than said first zone and under urea synthesis conditions to produce urea therefrom. The ammonia synthesis gas is suitably passed into the condensation and absorption zone at a pressure below 1000 p.s.i.g. and the condensate is suitably pressurized and passed to the urea synthesis zone operated at an elevated pressure, e.g. between 1700 and about 3500 p.s.i.g. The reaction effluent from the urea synthesis zone is preferably depressurized and heated to decompose ammonium carbamate to a gaseous mixture of ammonia, carbon dioxide and water, which is separated from the remaining effluent containing aqueous urea. The gaseous mixture is preferably passed to the condensation and absorption zone in which it is condensed and used to absorb carbon dioxide present in the raw ammonia synthesis gas. A portion of the raw ammonia synthesis gas may be diverted to a conventional carbon dioxide purification system and the carbon dioxide so obtained may be passed to the urea synthesis zone to react with ammonia. The ammoni