Determine the optimum tube dimensions for Robert evaporators through experimental investigations and CFD modelling: final report 2012/054
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Date
2017
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Sugar Research Australia Limited
Abstract
Experimental investigations were undertaken in a single tube pilot evaporator for nine tubes of
three different lengths and three different diameters to determine the optimum tube dimensions for
Robert evaporators. Heat transfer performance was determined at operating conditions typically
encountered in sugar factory evaporators. Juice of three brix levels were selected to mimic
conditions for the 1st, 3rd and 5th effects in a quintuple evaporator set. For each brix, the heat
transfer coefficient (HTC) was calculated at four juice levels, two headspace pressures and two
pressure differences between the steam chest and the headspace. Of the four juice levels, one juice
level was identified as the optimum juice level corresponding to the maximum HTC. In total, 432
tests were undertaken with nine tubes and a further 128 tests were replicated with four tubes. The
maximum HTC and optimum juice level results, linked together with a capital cost analysis and
sucrose loss considerations, determined the preferred tube dimensions for Robert evaporators in a
quintuple evaporator set.
Tubes of 3 m length and either 44.45 mm or 38.1 mm outside diameter are preferred for the 1st, 2nd and 3rd effects instead of the traditionally used tube of 2 m length and 44.45 mm outside diameter. The tube of 2 m length and 44.45 mm outside diameter is recommended for the 4th and 5th effects.
The investigations in this project were undertaken by Omkar Thaval for his PhD thesis at QUT “Investigating the effect of tube dimensions and operating conditions on heat transfer performance in a rising film vertical tube evaporator”.
Tubes of 3 m length and either 44.45 mm or 38.1 mm outside diameter are preferred for the 1st, 2nd and 3rd effects instead of the traditionally used tube of 2 m length and 44.45 mm outside diameter. The tube of 2 m length and 44.45 mm outside diameter is recommended for the 4th and 5th effects.
The investigations in this project were undertaken by Omkar Thaval for his PhD thesis at QUT “Investigating the effect of tube dimensions and operating conditions on heat transfer performance in a rising film vertical tube evaporator”.
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Keywords
Milling, Technology, Robert evaporator