Influence of Production Condition of High Hardness Solid Fuel Made from Coffee Residues on the Combustion Property

Abstract

Biomass is one of the sustainable energy sources and is the most suitable natural energy for storage and transport. We are suggesting a high hardness biomass briquette made from any plant biomass as an alternative coal coke. The high hardness biomass briquette is named ‘Bio coke’, described as ‘BIC’ below, and it achieves 10 to 20% substitution of coal coke for practical cupola furnace use. We, in the present study, examined the influence of composition on combustion property of BIC made from coffee residues. The coffee residues were assorted to outer skin (outer skin and pulp mixture, described as ‘OS’ below), inner skin (parchment and silver skin mixture, described as ‘IS’ below) and coffee bean grounds (instant coffee production residue, described as ‘IC’ below). BIC specimens were composed of IC100%, IC50%+OS50% and IC50%+IS50%, OS100% and IS100%. Measurement of ignition delay (time from heating start to flaming combustion start), duration time of flaming combustion and char combustion, and thermogravimetry were conducted under 698K air environment. As a result, the ignition delay and the duration time of char combustion were affected by not only combustion property of each component but crack generation condition during heating process. The ignition delay and the duration time of char combustion were shorten due to enlargement of reaction surface area caused by the crack generation. It is, additionally, considered that the crack generation condition could be controlled by mixing of components which have different thermal decomposition and combustion properties.