Spray dryers are critical items of processing equipment for producing common consumer products such as milk powder, detergents and paints. Poor performance is costly and dangerous in terms of thermal damage, consequent product wastage, and fire and explosion hazards. A common feature of all the research projects is the simulation of flow patterns inside spray dryers using modern Computational Fluid Dynamics packages, together with flow visualisation and other experimental techniques. Important sponsors of this work include:
- Australian Research Council
- Dairy Research and Development Corporation
- Bonlac Foods Ltd
- Ministry of Business, Innovation & Employment(formerly the New Zealand Foundation for Research, Science and Technology (FRST))
- Vic Cherikoff Food Ingredients P/L
- Lang Technologies P/L.
Significant advances have recently been made by our research group in optimising drying conditions for the production of hardwood lumber. We are using model predictive control techniques to minimise drying times subject to constraints on stresses which develop during drying. Several Australian hardwood timbers have been assessed using this technique, including ironbark (Eucalyptus paniculata) and blackbutt (Eucalyptus pilularis) timbers for which our optimised drying schedule dries the timber 10% faster than conventional schedules, and gives less than 25% of the amount of cracking. Collaborative research is being carried out in association with Boral Timber (Boral Ltd) to apply these schedules on an industrial scale. Boral Timber is one of the largest hardwood timber processors in Australia. The effects of variability in timber on the optimised schedules generated by our technique is being assessed, together with better mechanical property measurements for the timber.
Work is also being carried out in association with the University of Canterbury in New Zealand to improve modelling approaches for softwood timber, specifically radiata pine with the ultimate aim of applying the same optimised technique to improve the quality of timber. In future further collaboration would be made with Forest Research, New Zealand in this area.
Solar kilns and intermittent drying are being used, in an ARC Linkage project with Australian Choice Timber Supplies P/L (Greg Weir), to improve the quality of dried timber with low energy usage.
Forestry in Queensland
NSW State Forests Boral
CSIRO Forest Products Laboratory
Forest Research New Zealand
Australian Choice Timbers, Greg Weir
Spinning Cone Column Research
The Spinning Cone Column is a counter-current gas-liquid separation unit which has found industrial applications, particularly in the food processing industry. These applications include the processing of low alcohol wines, citrus processing, the production of instant coffee and tea and the removal of taints. A company, Flavourtech Pty Ltd, manufactures the columns in Australia and markets them in Australia and overseas.
In order to enable the Spinning Cone Column to be used further for flavour recover and other applications, the numerical modelling of the fluid flow in this equipment using CFX 4 (a Computational Fluid Dynamics package) is very important, and this is being carried out by our group. Once the fluid behaviour is modelled accurately, this simulation can be used to estimate how and where the column floods and how the column design affects the volatile stripping rate and the separation efficiency. This simulation will then be used to improve the design of these columns.
In addition, the influence of the gas/vapour flow on the column performance is being studied in order to fully understand the influence of column design and operation on performance. Experimental work is being carried out using fluorescence emission to measure liquid film thicknesses, and dimensional analysis is being used to characterise these data, which are being used to test the model predictions.