| 摘要 |
Integrated process for urea/melamine production comprising the operating steps of: (a)- urea synthesis from ammonia and carbon dioxide, obtaining molten urea and a gaseous mixture comprising steam and ammonia; (b)- condensation of said gaseous mixture comprising steam and ammonia, obtaining a cold aqueous ammoniacal solution; (c)- melamine synthesis from urea with formation of off-gases, comprising ammonia and carbon dioxide; (d)- absorption of the off-gases in at least one fraction of the cold aqueous ammoniacal solution obtained in said step (b), with formation of a carbamate aqueous solution; (e)- decomposition of the carbamate aqueous solution, obtaining ammonia, carbon dioxide and steam, and a residual aqueous ammoniacal solution; (f)- recycling of the ammonia and of the carbon dioxide obtained in step (e) for the urea synthesis; (g)- treatment of the residual aqueous ammoniacal solution obtained in step (e) for the recovery from it of ammonia and carbon dioxide for the urea synthesis. |
