Patent ID: 7414130

Claim:
An integrated process for urea and melamine production, wherein urea is produced in a urea plant of the so-called CO 2 or ammonia stripping type comprising a high pressure urea synthesis section operated at about 130-170 bar and comprising at least one urea synthesis reactor, stripper and carbamate condenser, connected one to the other so as to form a substantially isobaric loop, and a urea recovery section for separating urea from a carbamate aqueous solution, and wherein melamine is produced in a melamine plant wherein off-gases resulting as by-products of the melamine synthesis are discharged therefrom at a pressure between 2 and 30 bar and recycled to said high pressure urea synthesis section, the process comprising the steps of: feeding said off-gases coming from said melamine plant to an off-gas condensation section operated at a pressure substantially equal to the pressure of said off-gases; feeding said carbamate aqueous solution coming from said urea recovery section to said off-gas condensation section; condensing said off-gases with said carbamate aqueous solution in said off-gas condensation section obtaining a concentrated carbamate aqueous solution; and feeding the so obtained concentrated carbamate aqueous solution to said high pressure urea synthesis section.