| 摘要 |
<p>PURPOSE:To recover CO2 and NH3 efficiently and to circulate them for use, by stripping unreacted CO2 after removal of inert gas, followed by combined steps of high-pressure distillation and absorption. CONSTITUTION:A solution for synthesizing urea taken out from the synthetic pipe 1 is introduced into the stripper 6, brought into contact countercurrently with CO2 from the line 7 to discharge partly unreacted CO2 and NH3, and transferred from the line 10 to the distillation column 12. Most parts of the remaining CO2 and NH3 are separated and taken out from the bottom of the column to give a urea solution. Inert gas with CO2 and NH3 separated from the reaction pipe 1 and the gas from the distillation column 12 are introduced into the high-pressure absorption column 16 and brought into contact with an absorption solution so that all of CO2 and a part of NH3 are absorbed. The resulting absorption solution is sent to the carbamate condenser 34 and brought into contact with a mixed gas from the stripper 6 to form ammonium carbamate, which is transferred to the reaction pipe 1. Unabsorbed NH3 and the inert gas are transferred to the condenser 23 to separate liquid NH3, which is sent to the synthetic pipe 1.</p> |
