WERKWIJZE VOOR HET BEREIDEN VAN UREUM.

摘要

Urea is produced by (a) reacting NH3 with CO2 at 160-230 deg.C and 130-280 atmos. using a NH3:CO2 molar ratio of 3.4-6:1 to form a urea melt; (b) flashing the melt at 60-215 atmos. to produce a vapour and a liq.; (c) distilling the liq. in at least 2 stages with progressive pressure redn., at least one stage being effected in the presence of a CO2 stream, to produce an aq. urea soln. and overhead vapours contg. NH3, CO2 and H2O; (d) condensing the overhead vapours in contact with an aq. absorbent, in the presence of at least part of the vapour from (b), to form an aq. ammoniacal soln. of NH4 carbamate; (e) recycling the soln. from (d) to (a); and (f) dehydrating the urea soln. from (c) to produce solid urea.