| 摘要 |
A process for the combined preparation of ammonia and urea is described. An ammonia synthesis gas substantially comprising hydrogen, nitrogen and carbon dioxide is subjected to elevated-pressure scrubbing using a solvent having a physical action at temperatures of at most ambient temperature in order to remove acid impurities, in particular carbon dioxide. The loaded solvent is partially let down for removing co-absorbed inert gases by gassing, then regenerated without pressure and returned to the elevated-pressure scrubbing, and the carbon dioxide released during regeneration is used for the urea synthesis. In order to enable this carbon dioxide to be passed on to the urea plant in an energy-saving manner in pre-pressurised form, it is proposed to bring the pressure above the loaded solvent after the partial depressurisation to an intermediate value, to heat the loaded solvent in order to remove some of the carbon dioxide by gassing, and to subject the solvent partially regenerated in this manner to the last pressure-less regeneration step, and to cool the carbon dioxide removed by gassing during heating and discharge it at the intermediate pressure. |
