Optimised Fluidised Bed Dryer for Tea
Challenge
Fluid bed drying is a very effective drying method for products such as tea. But to achieve uniform air flow, traditional design methods rely on a high “pressure drop” across the perforated bed, which in turn leads to high electrical energy use for the fans
Solution
Took a new approach – instead of relying on high pressure drop for uniform air distribution, the vanes in the air delivery duct were used. Given the difficulty in designing and achieving true uniformity of vanes “Computational Fluid Dynamics” software was utilised, which employs finite-element techniques, to model the system on a computer. This approach allowed fine-tuning of the design of the vanes without having to build and test different models
Result
The new dryer consumed only 40% of the fan power which would have been required using the conventional design approach which equated to an on-going annual saving of approximately $55,000 (250 MWh of electricity). In addition, the reduced-pressure design enabled lower-cost axial fans to be used, instead of centrifugal – providing a significant capital cost saving. The initiative also reduced carbon dioxide emissions by around 240 tonnes per year
