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Optimization of woody biomass torrefaction in inert and oxidative atmospheres using combined experimental and modelling approach

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dc.contributor.advisor Gunarathne, RMDS
dc.contributor.author Devaraja, UMA
dc.date.accessioned 2023T03:45:24Z
dc.date.available 2023T03:45:24Z
dc.date.issued 2023
dc.identifier.citation Devaraja, U.M.A. (2023). Optimization of woody biomass torrefaction in inert and oxidative atmospheres using combined experimental and modelling approach [Master's theses, University of Moratuwa]. Institutional Repository University of Moratuwa. http://dl.lib.uom.lk/handle/123/22969
dc.identifier.uri http://dl.lib.uom.lk/handle/123/22969
dc.description.abstract Torrefaction is a thermochemical pretreatment method to increase the energy density of biomass. The process is carried out at 200-300 ⁰C in an inert atmosphere. However, large-scale use of inert gas is neither realistic nor economical. More than 50% of industrial flue gas in Sri Lanka is greater than 200 oC and has less than 10% oxygen content which is suitable as a torrefaction medium. Lab-scale torrefaction experiments were conducted for Gliricidia and Rubberwood, at 250-300 oC temperature range and 30–60 minutes in nitrogen and 3%, 6%, 9% oxygen environments to understand the torrefaction behaviour. TGA and FTIR were used to characterize raw and torrefied biomass. In the lab-scale experiments in inert torrefaction, Gliricidia and Rubberwood showed more than 30% mass loss under the most severe conditions, resulting in a 22.8% and 11.6% volatile drop, respectively. The higher heating value of the torrefied product increased from 18.9 MJ/kg to 30.15 MJ/kg for Rubberwood and from 19.46 MJ/kg to 28.2 MJ/kg for Gliricidia under the most severe conditions. The severity factor was modified by finding the optimum fitted parameter ω, establishing a feedstock-specific relationship between torrefaction severity and operating conditions. The normalized severity factor shows a linear correlation with the properties of torrefied biomass, which could facilitate torrefaction modelling. Rubberwood shows its optimum oxidative torrefaction properties at 300 oC temperature and 31-min residence time and 9% oxygen, whereas Giricidia shows it at 286 oC temperature at a 60-min residence time and 9% of oxygen. A process model was developed for oxidative torrefaction, and results show that CO2 has the highest volume fraction, followed by CO and CH4 in the non-condensable product and water has the highest fraction in the condensable product. Acetic acid, formic acid, phenols and furfurals were other dominant components. Keywords: Gliricidia, Rubberwood, Torrefaction, Oxidative torrefaction, Process simulation, Aspen Plus en_US
dc.language.iso en en_US
dc.subject GLIRICIDIA
dc.subject ASPEN PLUS
dc.subject RUBBERWOOD
dc.subject TORREFACTION
dc.subject OXIDATIVE TORREFACTION
dc.subject PROCESS SIMULATION
dc.subject CHEMICAL AND PROCESS ENGINEERING - Dissertation
dc.subject Master of Philosophy (MPhil)
dc.title Optimization of woody biomass torrefaction in inert and oxidative atmospheres using combined experimental and modelling approach en_US
dc.type Thesis-Abstract en_US
dc.identifier.faculty Engineering en_US
dc.identifier.degree Master of Philosophy en_US
dc.identifier.department Department of Chemical & Process Engineering en_US
dc.date.accept 2023
dc.identifier.accno TH5437 en_US


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