(<250 microns) wood flour on the AST Dryer effectively dried the flour from 5% moisture to 0.3-0.4% depending upon the amount of pitch or tar that was present in the feed. The amount of pitch in the wood flour is a factor that should be taken into consideration - increased amounts of pitch cause heat retention posing a potential fire hazard if the dried flour is stored for an extended period of time. The test unit was able to demonstrate a representative process, drying around 400kg/h of wet material with a 22kW central shaft drive motor. On the strength of these convincing tests the customer installed a 37kW drive unit with a capacity of 900 kg/h of wet material - 858 kg/h dry - and commenced commercial dry wood flour production.
Once dried, the pre-ground flour is blended with a resin and formed into a variety of continuously moulded shapes by extrusion. These extruded composites are structurally strong and can be used for a wide variety of structural applications such as garden decking, furniture, shelving, etc.
Wood flour is an excellent application for the AST Dryer and all of our customers have been completely satisfied with its performance and product quality outcome. Because it is non-abrasive, the AST dryer paddles require low maintenance. Colour consistency, including the controlled blending of pigments into the extrudate, meets customers' stringent requirements. This is mainly thanks to the relatively high air volume combined with the unique mixing action of the dryer paddles; these features ensure success in drying the wood flour without adding excessive heat and prevent hot spots - a common problem with some other types of dryer. Overall the AST Dryer meets and exceeds all our customers' expectations.
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