Product build-up in granulator

[Murec]

Our plant produces urea granules in rotary drum granulators. Droplets and dust of the product are pulled back by the induced airflow through the granulators and stick to the walls and roof of the breech. Removing the build-up is hard and dangerous - big chunks can fall on the workers.
I am trying to find a solution to prevent the urea build-up. Best would be to redesign the breech for improved airflow, but it would be extremely costly. We are trying water sprays for cleaning, vibrators on the walls, maybe non-stick coatings.
I would be thankful for any suggestions.

 

[witchdoc]

Molten urea tends to supercool when finely atomized. The first surface upon which the mist impinges will build up. You might first try using a larger nozzle. What process is used in the granulator (i.e. Spherodizer, falling curtain, ???). We have had good success in attaching a water spray chamber directly to the breeching. If you keep the inlet velocities low, you will minimize the impingment at the wet/dry interface. Take special precautions to prevent water from backflowing into the drum. The first nozzles should spray cocurrent with the airflow. Be sure that they are mounted out of the airstream.