Process heat integration for small scale bio-ethanol plant

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University of Dar es Salaam
The process heat integration with other energy sources has been considered as an alternative to minimize the energy cost incurred by small-scale bio-ethanol plants. Biogas generated from stillage, and syngas from rice husk gasification were the two alternatives considered in this study to replace or supplement the conventional energy sources in bio-ethanol production process. Due to low availability of stillage and high cost of constructing a bio-digester, the alternative of utilizing stillage as energy source was not pursued and instead biomass gasification was selected. The developed 100 kW gasifier was tested using rice husk which are readily available. The properties of rice husk were analyzed through proximate analysis, and those of stillage were obtained from literature. These properties were used in preparing the mathematical model for mass and energy balance. Through the analysis of the model, 34.2% of stillage produced in bio-ethanol production can meet the energy requirement in bio-ethanol production. The developed gasifier operates at an efficiency of 51% and produces syngas with calorific value estimated to be 2.02 MJ/kg. Utilizing rice husk gasification can replace the conventional energy sources with estimated 17.6% energy cost saving to bio-ethanol plants. These results show the potential of using both biogas conversions from stillage and biomass gasification as sources of energy to small scale bio-ethanol production plants.
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Biomass energy
Raphael, I (2011)Process heat integration for small scale bio-ethanol plant, master dissertation, University of Dar es Salaam (available at