Process for the synthesis of urea comprising a passivation stream at the stripper bottom

Abstract

A process for the direct synthesis of urea from ammonia and carbon dioxide with increased corrosion resistance, comprising, in the high-pressure synthesis section, a reaction step in a vertical reactor (R) fed with at least one stream of fresh carbon dioxide containing a passivating agent and a decomposition-stripping step of the non-converted reagents, wherein the gas-liquid mixture collected at the head of the reactor is separated into a gaseous stream and a liquid stream fed to the tail and head of the stripper, respectively.

Description

technical field [0001] The present invention relates to an enhanced process for the synthesis of urea containing a passivation stream at the bottom of a stripper. Background technique [0002] In particular, many methods are known in the prior art for the production of urea. [0003] The synthesis of urea is achieved by reacting ammonia and carbon dioxide at high pressure and temperature, followed by separation of urea from the mixture containing unreacted products and recycling it to the reactor. [0004] Therefore, all industrial processes for the preparation of urea are based on a direct synthesis according to the following reaction: [0005] [0006] The synthesis proceeds in two distinct reaction steps: [0007] [0008] [0009] In the first step (1a), an exothermic equilibrium reaction with a high reaction rate takes place at room temperature, however, in step (1b), where high temperatures are necessary, high pressures are required to achieve a favorable eq...

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Problems solved by technology

[0029] However, this solution requires further specialized equipment, i.e. a compressor at additional expense, also requiring regular maintenance interventions

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