FACULTY OF TECHNOLOGY
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Item Combustion characteristics of briquettes produced from three binders and torrefied gmelina arborea (robx.) sawdust(2023) Bello R.S.; Olorunnisola A.O.; Omoniyi T.E.; Onilude M.A.Considering the energy potential of briquettes, there are several undesired harmful qualities such as intense yellow flame and smoke. Torrefaction was deemed a suitable technological solution, therefore, the study investigated the combustion properties of briquettes made from Gmelina arborea sawdust and three binders used print paper (UPP), newsprint (Np) and clay (CL). Materials and Methods: Experiments were conducted using a hydraulic press and a biomass stove. The 3 torrefied feedstock samples (TS 30, TS 45 and TS 60 min) were mixed with binders at 10, 20, 30, 40 and 50% w/w at 1.67 kPa applied pressure and 5 min residence period to produce briquettes. The results were statistically analyzed at significance level using ANOVA. Results: Briquette densities decreased with an increase in torrefaction time with strong positive correlations between densities of the same binder type, concentration and torrefaction time. An increase in binder concentration enhanced the combustion characteristics of UPP and Np briquettes positively, with significant negative effects on CL briquettes. Torrefied used printing paper briquette burns with non-luminous flame and reduced smokiness as binder concentration increases, while newsprints briquette produced excessive smokes. Briquettes produced from used printing papers at 45 min torrefaction had better performances in terms of energy values, product flammability and reduced smokiness. Clay-bonded briquettes had delayed ignition 7-10 min and failed to burn with flame, rather than by char combustion. Conclusion: Torrefaction time, binder type and concentration had significant positive effects on the combustion characteristics. Clay had poor effects on combustion characteristics.Item Effect of residence time on characteristics of torrefied sawdust produced from gmelina arborea (roxb) wood(2022) Bello R.S.; Olorunnisola A.O.; Omoniyi T.E.Biomass feedstock remains a critical ingredient in all densification studies and the process conditions under which these materials were produced are significant to its performance. Conventionally, feedstocks are utilized in briquetting without major technological processing which is consequential on product characteristics. In this study, sawdust of Gmelina arborea subjected to thermochemical pre-treatment conditions was analysed and characteristics were compared with untreated material. Materials and Methods: Untreated sawdust of Gmelina arborea wood obtained from a sawmill in Ishiagu was torrefied at three residence times of 30 min, 45 and 60 min at a temperature of 250EC in a batch reactor and the products were characterized to determine their physical and chemical characteristics. Results: The particle-size distribution of untreated sawdust showed greater proportions of coarse and fine pin particles (58.03%) and (38.00%), respectively, requiring no grind with a mean particle density of 159.30±0.02. The proximate analysis of untreated sawdust at 7.78% moisture content revealed a volatile matter content of 72.93, 2.19% ash content and 17.10% carbon content. The proximate analysis of torrefied samples revealed a significant loss in volatile matter contents to 21.02% as residence time increased to 60 min, the fixed carbon increased from 17.10-65.38% and calorific values from 17.38 MJ kgG1 for raw sawdust to 26.28 MJ kgG1 as residence time increases. Reduction in volatile matter contents increased the energy values of torrefied sawdust. Conclusion: Thermochemical pretreatment of the feedstock significantly increase the material fixed carbon content and energy values of the Torrefied sample, reduced the volatile matter-the smoke-generating component of sawdust considerably and improved the product’s characteristics in briquetting.