Patent ID: 7220882

Claim:
Process for urea production of the type comprising the steps of: carrying out a reaction between ammonia and carbon dioxide in a high-pressure reactor obtaining a reaction mixture comprising urea, carbamate and unreacted ammonia in aqueous solution, subjecting said reaction mixture to an autothermal stripping treatment in a decomposition unit of the carbamate obtaining a first gaseous flow comprising ammonia and carbon dioxide and a first liquid flow comprising urea and residual carbamate in aqueous solution, recycling said first gaseous flow comprising ammonia and carbon dioxide to said reactor, subjecting said first liquid flow to a stripping treatment in at least one carbamate decomposition unit operating at medium pressure of a urea recovery section, obtaining a second gaseous flow comprising ammonia and carbon dioxide and a second liquid flow comprising urea, wherein it also comprises the following steps: carrying out a partial condensation of said second gaseous flow comprising ammonia and carbon dioxide in a condenser to give a mixed liquid/gaseous flow consisting of a carbamate solution and uncondensed gases comprising ammonia and carbon dioxide, separating said mixed liquid/gaseous flow in a separator to give a third liquid flow substantially consisting of carbamate in aqueous solution and a third gaseous flow consisting of said uncondensed gases, washing said third gaseous flow consisting of said uncondensed gases in a column having a packed portion, said washing being carried out in said packed portion in countercurrent with a flow of a carbonate solution, obtaining a fourth gaseous flow essentially consisting of ammonia and a fourth liquid flow comprising a carbamate solution in which the carbon dioxide contained in said uncondensed gases has been absorbed.