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Upgrading of a traditional sugar cane mill to a modern milland assessing the potential of energy saving during steady stateand transient conditions: part II: models for a modifiedcogeneration unit
KTH, Superseded Departments, Energy Technology.
KTH, Superseded Departments, Energy Technology.
Addis Ababa University, Ethiopia.
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.ORCID iD: 0000-0002-3661-7016
2015 (English)In: Biomass Conversion and Biorefinery, ISSN 2190-6823Article in journal, Editorial material (Refereed) Published
Abstract [en]

It is known that there is a significant amount ofthermal energy used for the sugar cane industry for the purposeof power production and for use in the sugar or ethanolprocessing in cane sugar industries. Likewise, it is understoodthat there are substantial amounts of waste heat that is notbeing recovered, in particular for traditional sugar mills. Regardlessof this, energy conservation is given less considerationas compared to operational convenience due to the factthat sugar mills are self-sufficient in energy (heat and power).The identification of such potential heat loss areas (especiallyduring transient conditions) suggests the sugar mills play avital role in energy saving. In this study, a modified setup ofthe base case plant considered in part I of this paper is assessedfor its energy potential and possible major heat losses duringsteady state and transient conditions where 2-h stoppage of themill presses are considered to occur. For the modified setup,there are two major scenarios considered having two subscenarioseach. The result of the assessment showed that thesteady state assumption scenario of the modified plant (wherebagasse drying is not considered) indicated a 20 % reductionin the losses considered which resulted in a 57 % power generationincrease as compared to the steady state model of thebase case plant. It is also possible to save excess bagasse bydrying the bagasse for later use during unexpected stoppage.The carbon dioxide emission (amounting 29 t/day in case 2aof this study) that occurs during the use of fuel oil during suchstoppages will thus be avoided. The simple economic analysisshowed that it is only in case 2a where fuel oil cost is includedin the operation cost that resulted in a negative NPV. Since therest of the scenarios use bagasse as a fuel which is free, theNPV for all was positive. For the electricity price of 0.04 US$/kWh and discount rate of 15 %, the minimum paybackperiod attained is about 3 years (case 1b) where the bagassemoisture content is 30 % whereas the maximum payback periodis 6 years (case 1a) where there is no bagasse dryingconsidered.

Place, publisher, year, edition, pages
Keyword [en]
Sugar cane, Bagasse drying, Steady state, Transient state, Heat loss
National Category
Energy Engineering
Research subject
Energy Technology
URN: urn:nbn:se:kth:diva-185730DOI: 10.1007/s13399-015-0180-8ISI: 000377398800011OAI: diva2:923182
Sida - Swedish International Development Cooperation Agency

QC 20160512

Available from: 2016-04-25 Created: 2016-04-25 Last updated: 2016-07-05Bibliographically approved

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