Problem No. 33: Excessive amount of carbamate solution from recirculation section

The recirculation or distillation section in a urea plant where unconverted carbamate is separated from the urea/water mixture is a critical section of a urea plant that influences the overall performance of the plant. Too much carbamate solution recycle back to the synthesis section will increase the amount of water in the synthesis and will negatively influence the reactor conversion figures. Fouling in the recirculation section can sometimes cause these operational problems, but how can fouling be identified as the root cause of a problem?