Abstract:
Ammoni a and carbon d iox i de are compressed to a pressure in the range of
150-220 bar and a temperature of l80-220oC, an exothermic reaction occurs
to form carbonate which is then dehydrated to urea.
The unconverted carbonate and excess reactants are removed in the solution
purification stages and returned to the reaction system. The urea solution
is evaporated to achieve required concentration for fertiliser or technical
grade urea. If a low biuret content is required, the product is
concentrated by crystallisation. The final shaping of the product is almost
always done by prilling.