Problem No. 27: How do you clean the scraper in a prilling tower?

A scraper rotates above the floor of the prilling tower and moves the prills from the bottom of the prilling tower to the conveyor belt. At higher plant loads and/or under summer conditions the prills are not completely solidified and are still soft when reaching the bottom of the prilling tower. These soft prills clog up the scraper forming a hard layer of solid urea. This kind of fouling can also build up on the walls and ceiling of the prilling tower and at regular intervals cleaning becomes necessary. But how can this be done safely? This Round Table discussion starts with a description of a related safety incident as reported in UreaKnowHow.com’s urea incident database.