A systems and resistance analysis of heat loss through an industrial flighted rotary ore dryer

Sheehan, M.E. (2006) A systems and resistance analysis of heat loss through an industrial flighted rotary ore dryer. In: Proceedings of 13th International Heat Transfer Conference. From: 13th International Heat Transfer Conference: IHTC-13, 13-18 August 2006, Sydney, NSW, Australia.

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Abstract

Flighted rotary dryers are flexible unit operations capable of handling wet sticky material such as mineral ores and sugar. This paper outlines the experimental characterisation of one of the BHP Billiton Yabulu nickel refinery's industrial flighted rotating mineral ore dryers. The ore dryer examined in this work processes approximately 150 t/h of laterite ore from 27% to 3% moisture by direct contact with hot combustion gases. Experimental data are utilised to calculate the magnitude of the heat losses from the dryer shell. Process instrumentation data collected over a steady period of operation were combined with a range of operational and material properties to solve for unknown heat losses in a system of steady state mass and energy balance equations. Heat loss from the dryer was determined to be 5.8 GJ/h, which represents 3.5% of the combustion fuel as lost waste heat. Accounting for measurement error in the experimental data, heat loss may be as high as 31 GJ/h. Model sensitivity to measurement errors is discussed in terms of impact on determination of the overall heat losses. Inlet combustion gas temperature and wet ore feed rate were identified as the most sensitive system measurements. Measurement of the dryer surface temperature, via infrared thermal imaging, was also undertaken. This data was utilised within an alternative fundamental steady state thermal resistance analysis to determine heat losses from the dryer shell. Resistance terms included convection from the hot gas, conduction through the shell and convection and radiation from the surface to the atmosphere. Heat transfer coefficients were taken from standard empirical correlations describing free and forced convection as well as radiation. Heat losses determined in this manner were comparable to the systems analysis: 3 GJ/h. Comparison between the alternative methods of calculation are made and integration of the thermal resistance analysis into more complex rotary dryer models as well as the use of the resistance analysis to model insulation effects is discussed.

Item ID: 4286
Item Type: Conference Item (Refereed Research Paper - E1)
Keywords: drying; rotary; systems analysis; heat; modelling; numerical
ISBN: 1-56700-225-0
Date Deposited: 21 Oct 2009 04:37
SEO Codes: 86 MANUFACTURING > 8614 Machinery and Equipment > 861403 Industrial Machinery and Equipment @ 70%
85 ENERGY > 8507 Energy Conservation and Efficiency > 850703 Industrial Energy Conservation and Efficiency @ 30%
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