In 1967, the Stamicarbon CO₂ Stripping Process revolutionized the urea process.

Characteristic of this process is that the major part of the recycle of both nonconverted NH₃ and nonconverted CO₂ occurs via the gas phase, such that the recycle is not associated with a large water recycle to the urea synthesis. Heat, as 20 bar steam, is only supplied to the high pressure CO₂ stripper and all downstream sections make use of recovered heat in the high pressure carbamate condensor (unconverted ammonia and carbon dioxide are condensed to form ammonium carbamate and consequently generate LP steam).

printable PDF diagram 130 Kb

In order to realize maximum urea conversion in the synthesis section at a synthesis pressure of approximately 140 bar, a molar ratio of ammonia to carbon dioxide of 3 to 1 is required. At these conditions the synthesis temperature will be about 183 °C.

The CO₂ stripping process results in significant energy savings in comparison to the conventional processes (0.8 t steam/ tonne urea vs. 1.6 t steam/tonne urea).

In Stamicarbon’s first generation CO₂ stripping plants, the high pressure carbamate condensor is a falling film type condensor and a vertical reactor is used. See diagram above.