| 摘要 |
In a urea producing method by synthesis, the improvement which consists in feeding liquid ammonia in excess to the reactor so that a urea solution which contains ammonium carbamate is produced, the carbamate is decomposed in a high-pressure decomposer and the stripping agent is an inert, oxygen-containing gaseous stream, the carbamate decomposition products are sent to a high pressure condenser and ammonium carbamate is formed, whereafter the carbamate is separated from the inerts and the solution of urea coming from the high-pressure decomposer is fed to a medium-pressure decomposer which is fed through its bottom with inerts. The heat for operating the medium-pressure decomposer is a hot condensate from the high-pressure-decomposer-heating steam, and the products of decomposition of the carbamate coming from the medium-pressure decomposer are sent to a medium-pressure condenser together with a solution of ammonium carbonate coming from the low-pressure sections of the installation. Virtually pure, nonpolluting waters can be discharged from the installation. |
