FIELD: chemistry.
SUBSTANCE: present invention relates to an improved integrated method for producing urea/melamine, involving a) synthesis of urea from ammonia and carbon dioxide, obtaining molten urea and a gaseous mixture of water vapour and ammonia, b) condensation of the obtained gaseous mixture of water vapour and ammonia to obtain a cold aqueous ammonia solution, c) synthesis of melamine from urea with formation of exhaust gases containing ammonia and carbon dioxide, where d) exhaust gases are absorbed in at least one portion of the cold aqueous ammonia solution obtained at step b) to obtain aqueous carbamate solution, e) decomposition of aqueous carbamate solution to obtain ammonia, carbon dioxide and water vapour, as well as an aqueous ammonia solution residue, f) return of ammonia and carbon dioxide obtained at step e) to synthesis of urea and treatment of the aqueous ammonia solution residue obtained at step e) which is optionally mixed with a portion of the cold aqueous ammonia solution obtained at step b) in order to separate ammonia and carbon dioxide used for synthesis of urea, as well as to an integrated installation for producing urea/melamine.
EFFECT: reduced amount of special equipment, which is considerably large sized, required for processing exhaust gases.
10 cl, 3 dwg
