Air-lifted urea

Thread Content

The unit’s urea production capacity is 400,000 tons per year, and the process used is the stripping process. There is a problem that we hope experts can help us resolve: when the reverse spray nozzles are in use in the urea evaporation system, no liquid remains in the urine tank during shift handovers. With the production load remaining unchanged, the ammonia consumption for urea production is about 6 kilograms higher than normal. The specific process flow is as follows: flash tank – urine tank – urine pump – first and second stage evaporation – melting pump – granulation tower (the valve at the top of the tower is closed when using reverse spray nozzles, and the output from the melting pump returns to the urine tank). Observed phenomena: 1. The temperature of the urine tank was normal at 75 degrees; after starting the circulation, the temperature of the urea solution rose to 108 degrees ； 2. Indicators for maintaining flash vaporization temperatures in stages 1 and 2 ； 3. The vacuum levels in sections 1 and 2 have decreased by about 10 Kpa compared to the specified values; 4. All other parameters remain unchanged. Now there is suspicion that it could be the urine tank, with the rising temperature of the urine causing urea hydrolysis. It may be caused by high temperatures leading to significant evaporation of urine, which results in the escape of ammonia. I would appreciate some guidance from the experts.