The nozzles of a urea fluid bed granulation form the most essential part of a fluid bed granulation plant. Each licensor has developed its own specific nozzles and its features have a significant impact on the performance and efficiency of the granulation plant. Common in every nozzle is that urea melt is mixed with air although in which way the mixing is taking place differs widely between the different technologies. In the Uhde Fertilizer Technology the nozzle producers tiny droplets which solidify and join the seed material by an accretion process leading to a very hard granule. Stamicarbon’s fluid bed nozzle produces a layer of urea melt, which solidifies on the seed material forming an “onion” kind of granule leading to a very spherical shape. In a Toyo Engineering Corporation fluid bed granulator each nozzle forms a spouted bed where vigorous mixing occurs leading to round and uniform granules. Urea Casale applies a nozzle, which generates very fine droplets due to the fact that in the nozzle an emulsion of urea melt and air is formed, which is sprayed out of the nozzle. The very fine urea melt droplets make it possible to apply a urea melt feed to the granulator with a higher water content as the water is able to
evaporate from the fine droplets. This Round Table discussion discusses the problem of choking of such a nozzle: what can be the various causes and solutions. Via several rounds of questions and answers the problem area and a most likely root cause has been identified, which could solve the problem for this urea producer.
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