Patent ID: 8080687

Claim:
A method for reducing aerosol emissions from a urea granulation plant with the treatment of the resulting scrubber bleeds, comprising: producing urea with a granulator from a concentrated urea solution and an evaporation of the included water, giving urea granulates and an exhaust of dust, ammonia and ammonium isocyanate; subsequently scrubbing or removing the dust; and releasing a first stream of an exhaust of air and ammonia, and a second stream of ammonium isocyanate and water in a following aerosol stage with a specially designed spray and collection pads; wherein the second stream of ammonium isocyanate and water is fed into a isomerisation unit where the fraction of ammonium isocyanate is isomerised back to urea, whereas the isomerisation of ammonium isocyanate to urea is carried out in a stripping column with the feeding of low pressure steam to the bottom of the column; and the resulting urea in the stripping column is fed into a liquid phase, and the remaining ammonia and carbon dioxide are released to the head of the column.