Development Of An Appropriate Biomass Briquetting Machine For Use In Rural Communities

ABSTRACT

Biomass is naturally abundant in rural communities but is generally considered to be a waste in

most developing countries of the world where it is used inefficiently in its traditional form. The

effective utilization of these materials offers many advantages among which is a renewable and

sustainable energy feedstock for the production of solid fuel – briquettes - for heating

applications. Attempts have been made in developing machines for commercial briquetting of

biomass in developing countries but the numerous failures of these machines have inhibited their

extensive exploitation. The objectives of the study were to design and construct a biomass

briquetting machine suitable for rural communities; undertake a performance evaluation of the

briquetting machine using sawdust, rice husk, wheat husk and palm kernel shell; determine the

physical and combustion properties of the briquettes; and to determine the optimum biomassbinder

mix for each of the biomass samples using cassava starch as the binding agent. A

briquetting machine suitable for commercial production of biomass briquettes was designed and

constructed at a cost of about N35,000.00 (USD218) with a production capacity of 927

briquettes/hr. Each of the biomass samples and the binder were mixed at ratios of 100:15,

100:25, 100:35 and 100:45 in weight using 3700, 2000, 1750 and 1250cm3 of water per kg of

sawdust, rice husk, wheat husk and palm kernel shell respectively for mixing. The briquettes

produced were subjected to physical and combustion tests. Both the physical and combustion

properties of the briquettes vary with the binder levels (P < 0.05). Palm kernel shell briquettes

produced the highest compressed density of 0.9917g/cm3 while briquettes from wheat husk gave

the least compressed density of 0.3500g/cm3. The best sawdust briquette was produced at the

100:25 biomass-binder ratio having a compressed density of 0.7269g/cm3, relaxed density of

0.2518 g/cm3, compaction ratio of 2.9:1, durability rating of 91.43%, water resistance time of

7.86hrs, volatile matter of 67.08%, ash content of 19.21%, fixed carbon of 13.71% and a heating

value of 27.17MJ.Kg-1. Rice husk gave the best briquette at the 100:45 biomass-binder ratio with

a compressed density of 0.8434g/cm3, relaxed density of 0.4383g/cm3, compaction ratio of 2.3:1,

durability rating of 99.90%, water resistance time of 3.57hrs, volatile matter of 72.34%, ash

content of 9.54%, fixed carbon of 18.12% and a heating value 30.45MJ.kg-1. The best briquette

from wheat husk recorded at the 100:15 biomass-binder ratio had a compressed density of

0.7177g/cm3, relaxed density of 0.2974g/cm3, a compaction ratio of 2.2:1, durability rating of

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99.30%, water resistance time of 2.67hrs, volatile matter of 84.16%, ash content of 7.12%, fixed

carbon of 8.72% and a heating value of 31.18MJ.Kg-1. For the palm kernel shell whose biomassbinder

ratio was limited to 100:15, gave a compressed density of 0.9917g/cm3, a relaxed density

of 0.6518g/cm3, a compaction ratio of 1.4:1, a durability rating of 99.04%, a water resistance

time of 3.38hrs, a volatile matter of 80.41%, ash content of 14.89%, fixed carbon of 4.70% and a

heating value of 28.55MJ.Kg-1. The heating values calculated for the briquettes produced from

sawdust, rice husk, wheat husk and palm kernel shell at the optimum biomass-binder ratios were

sufficient enough to produce heat required for household cooking and small scale industrial cottage applications.