The customer wanted a mixer that could be cleaned quickly and easily between batches to prevent batch to batch contamination and also provide additional benefits in terms of performance, operational flexibility and faster product turnaround.
As part of a new line, the mixer was a significant unit in the major technology upgrade at the plant. Ploughshare mixers were already employed on similar lines but the customer had encountered problems with their cleaning and was keen to avoid this in the future.
Hosokawa Micron engineers developed a 1,700-litre Vrieco Nauta conical blender, which incorporates a cantilever screw and semi domed cover. The cantilevered design eliminates the bottom bearing and potential for bearing wear in the product zone while the semi domed cover means no sharp corners between vessel cover and wall, which again helps with cleaning.
After the mixing cycle is complete and the blender discharged, the main orbit arm parks automatically against a set of water spray nozzles recessed into the mixer wall and hot water is injected against the screw, which rotates to ensure all the screw surfaces are wetted and cleaned. The open screw design facilitates water drainage and the recessed spray nozzles are fed via an externally mounted spray lance.
In the parked cleaning position the top of the orbit arm is cleaned by a set of fixed spray nozzles and a powerful centrally located Toftejorg spray ball completes the vessel cleaning.