Design and Thermal Energy Analysis of Sugarcane Bagasse Dryer to Improve Thermal Efficiency of Boiler for Ethiopian Sugar Factory. (A Case for Wonji/Shoa Sugar Factory)
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Date
2018-02
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Addis Ababa University
Abstract
Sugarcane Bagasse is the fibrous residue of sugar cane stalk coming from the mills after crushing
and extraction of juice. It is used as a fuel for boiler to generate energy. In Wonji/Shoa sugar factory
a sugarcane bagasse of 52% moisture content which is very high moisture content in history of the
sugar factory is used as a fuel for boilers to generate steam. If the moisture content of bagasse is
high its heat generation capacity or calorific value is lower; indirectly that means the boiler
efficiency become low, because it’s heating value is reduced and it cause the largest loss in the
boilers due to the moisture carries the latent heat of vaporization up the stack.
This study is aimed to reduce this moisture content of sugarcane bagasse and so increase the thermal
efficiency of boiler for Wonji/Shoa sugar factory. To do that, a Fluidized Bed Bagasse Dryer has
been designed and the thermal analysis of the system was also carried out by ANSYS Fluent.
The Fluidized Bed Bagasse Dryer uses the hot flue gases that comes from boiler to chimney which
is optimum solution to enhance thermal efficiency of boiler. In other way, re-using this flue gases
for bagasse drying improves the environmental pollution. The bagasse and the hot flue gases mixed
in the drying chamber of Fluidized Bed Bagasse Dryer to evaporate the water contained in the
bagasse. Finally, this designed Fluidized Bed Bagasse Dryer enables to reduce bagasse moisture
content from 52% to 41% and also increases the efficiency of boiler by 5.5% from 70 to 75.5%
according to the analysis done analytically and using ANSYS Fluent. Both analysis gives almost
the same result. In addition, the total cost of the dryer was estimated to be 1,310,136.146 Ethiopian
birr. By installing this bagasse dryer, the factory can increases its income by 17,364 Ethiopian birr
per day and recover this cost within 3.14months.
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Keywords
Wonji/Shoa Sugar Factory, Thermal Energy, Thermal Efficiency, Boiler, Sugarcane Bagasse Dryer