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The palmyra palm shell is one of local biomass in Songkhla Province. This biomass is the residue from processing of ripe palmyra palm fruit. The production of palmyra palm shell charcoal briquettes (PSCBs) for using as biofuel in household and grinder restaurant is an interesting way. The objectives of this study were therefore to study the effects of binder types and ratios on the quality of PSCBs by using solar greenhouse drying (SGD) system. The quality of PSCBs was considered in terms of proximate analysis, ultimate analysis, heating value, compressive strength, density and crumbling. The drying kinetics, production cost and payback period of PSCBs were also studied. The binders that used in this study included tapioca flour, tapioca residue and native tapioca starch. The proportions of binders were 4, 7 and 10 % (wt), respectively. The spiral compression machine was used as charcoal briquettes making machine. The obtained PSCBs had hexagonal prism geometry with diameter of 5 cm, length of 10 cm and at the center of PSCBs has a hole with diameter of 1.5 cm. The moistened PSCBs were dried by SGD system until their final moisture content were lower than 8 % (wet basis). The results showed that drying of PSCBs with SGD system to the desired final moisture content can be done within 2 days. Type and ratio of binders had small effects on the quality of PSCBs, considering from the results of proximate analysis, ultimate analysis and heating value. The lower heating values (LHV) of PSCBs were in the range of 25.48-27.43 MJ/kg. Type and ratio of binders had effects on compressive strength, density and crumbling of PSCBs. Mixing of binders with the ratio of 4 % (wt) was not appropriate to produce the PSCBs due to they were highly crumbling. Production of PSCBs by adding the proposed binders with the ratios of 7 and 10 % (wt) obtained the PSCBs which pass the charcoal briquettes standard. However, adding more ratio of each binder into charcoal mixture led to higher smoke during burning of PSCBs. Production of PSCBs with 7 % (wt) of tapioca residue provided the lowest production cost and payback period.
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