IE35308L - Urea production - Google Patents

Abstract

1341497 Urea SNAM PROGETTI SpA 19 April 1971 [2 April 1970] 25977/71 Heading C2C A process for producing urea comprises: feeding carbon dioxide and ammonia to a synthesis reactor maintained at an elevated pressure and temperature, the ammonia being in excess with respect to the stoichiometricallyrequired value; reacting the carbon dioxide and ammonia in the reactor to produce urea contaminated with ammonium carbamate; conveying the liquid stream coming from the reactor and comprising urea, water, ammonium carbamate and ammonia to an ammonium carbamate decomposer operating at the same or substantially the same pressure as that in the reactor and at an elevated temperature; subjecting the ammonium carbamate to decomposition in the decomposer, by means of a countercurrent gaseous stream; removing from the lower region of the decomposer a liquid stream consisting essentially of urea, water and dissolved ammonia; subjecting a gaseous stream coming from the upper region of the decomposer and comprising NH 3 , CO 2 and water to condensation in a condenser operating at a pressure which is the same or substantially the same as the pressure in the reactor and at an elevated temperature ; recycling the condensed decomposition products from the condenser to the reactor; and introducing into the bottom of the decomposer, into the condenser or into the gaseous stream at any point between the decomposer and the condenser, at least one of oxygen, a gaseous mixture containing oxygen and a substance which is capable under the operating conditions of developing oxygen, as a corrosion inhibitor. [GB1341497A]