Evaluation and optimization of process conditions for Lime saccharate clarification in the manufacture of plantation white sugar:The case of Metahara sugar Factory
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Date
2011-06
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Addis Ababa University
Abstract
This paper analyses the possibility to adopt lime saccharate clarification in
Metahara Sugar Factory and also tries to find optimum process conditions for
better juice purification. Mixed juice samples of 5 l each were taken from
weighed mixed juice pumps’ return line and pretreated so as to be used for
settling test. To get the targeted P2O5 content in juice, calculated amount of
phosphoric acid was added to the sample and subjected to heating to
750C.Then, the pH was raised to the pH of 8.5-9.5 by the addition of lime or
lime saccharate, heated to the boiling point. The prepared sample was taken
and poured in to the 1000 ml graduated cylinder containing flocculant
(separan).The required parameters were determined from the clarified juice
sample. The data obtained from the comparative experiments were subjected to
statistical analysis using design expert software whereby the significance was
set at 5% level. The result of the experiment has shown that mixed juice
sample from different combinations of cane varieties did not show any
significant variation in quality parameters at 5% significance level. At P2O5
content of 300ppm and separan concentration of 3ppm, the upper limit of the
preliming pH of 9.5 gave better results for lime saccharate such as purity of
84.7%, CaO of 936ppm, and turbidity of 477TU. But, when the P2O5 content
was increased to 350ppm, at separan concentration at 3 ppm, the mid value,
pH of 9, gave better results i.e, purity of 84.8%, turbidity of 163 Tu, settling
rate of 10 cm/min, reducing content of 0.52%. On the other hand, when the
P2O5 content was raised to 350 ppm with a separan concentration lowered to
1ppm, the lower limit value of PH=8.5 gave better values. Furthermore,
analysis of data of both treatments using the design expert software has proved
to be significant for all the parameters except that of CaO. The analysis had
also shown that the optimum process parameters of clarification were identified
to be pH=8.87, P2O5=321.15 and separan concentration of 3 ppm, which gave
acceptable values of the response variables considered. Using the optimum pH,
evaluation of the chemical consumption revealed that there is about 71%
reduction in lime consumption which can be taken as a positive outcome to
bring cost reduction and increased profitability to Metahara Sugar Factory in
particular and all other sugar factories in general.
Key words:Sugar,Clarification,Lime saccharate,Optimization.
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Keywords
Sugar, Clarification, Lime Saccharate, Optimization