Blocked spray nozzles are a widespread problem in fluidised bed systems in which very fine or tacky products are processed. By using ABC nozzles, the pharmaceutical excipient manufacturer DMV Fonterra Excipients has succeeded in avoiding unplanned downtimes.
Anti-bearding cap technology (ABC nozzles) is well-established in the field of tablet coatings. The use of these nozzles prevents the spray fittings from becoming blocked and ensures that the spray quality remains consistent. In practice this means an increase in production reliability and greatly simplified, tool-free operation. Furthermore, optimised internal channels prevent sedimentation. The use of ABC nozzles in fluidised bed systems is, however, new. Until now, multi-head nozzles have been used in this field – a solution which is not without merit. These nozzles are used to distribute the spray liquid over a wider contact area. This would also be possible using many individual nozzles, but the enormous amount of piping needed for this would ultimately lead to the use of one, or in the case of larger system diameters, several multi-head nozzles.
With very fine or extremely tacky products, a film forms on these nozzles and the nozzles regularly become blocked. The cause: dust lands on the nozzle, forms into clumps and blocks the nozzle. The spray from the nozzles then becomes very uneven – often unnoticed at first – which at the very least reduces the productivity of the system, but often also has a negative effect on product quality. If blockages or the like occur, the consequences are often expensive. Investment in system monitoring is also required.
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