ES390189A1 - Process for the production of urea - Google Patents

Abstract

Procedure for the production of urea, starting from NH3 and CO2, characterized in that it comprises the following stages: reaction of carbon dioxide and ammonia in the synthesis reaction vessel at elevated pressure and temperature, the ammonia being in excess with respect to the stoichiometric value; - shipment of the products leaving the reaction vessel and consisting essentially of urea, water, carbamate and ammonia, to a carbamate decomposer operating at the same synthesis pressure, or substantially at the same synthesis pressure, and at elevated temperature and in which said outgoing products find vaporized ammonia and/or another substance such as CO2, O2, air or any other in countercurrent, heat being transferred to said liquid stream by means of a fluid that works as an indirect exchanger; - sending to the subsequent treatments the liquid stream that leaves the bottom of the decomposer and essentially consists of urea, water and dissolved ammonia; - sending the gas stream leaving the upper part of the decomposer and consisting essentially of NH3, CO2 and water, to a condenser operating at the same synthesis pressure, or at substantially the same synthesis pressure, and at elevated temperature, producing this gas stream, by condensation, steam suitable for use in other parts of the plant; - recycling of the liquid stream leaving the condenser to the reaction vessel, by gravity, by means of an ejector that uses ammonia to be sent to the synthesis as a motor fluid, or by any other means; - introduction into the cycle and exactly at the bottom of the decomposer, in the condenser or at any other point between the decomposer and the condenser, of oxygen and/or air or other mixtures containing oxygen, or substances that in the operating conditions give off oxygen . (Machine-translation by Google Translate, not legally binding)