Investigation on gasification of coffee husk in CO2, H2O, and mixed atmospheres

Abstract

Coffee husk, a residue from coffee production, could become a potential feedstock for gasification if a comprehensive engineering profile of this feedstock is well established. This study focused on investigating the coffee husk characteristics and its behaviors during pyrolysis and gasification. The proximate analysis results showed that coffee husk had a high volatile matter of 69.8 %. However, the high ash content (9.2 %) should be considered due to its negative contribution to the system. The higher heating value (HHV) of coffee husk was 18.3 MJkg-1, comparable with woody biomass. The TGA- DTG results showed that the degradation of coffee husk began at 245 oC and achieved the maximum weight loss rate (Rmax = 0.4 %oC-1) at 310 oC. Coffee husk char gasification under 20 % H2O (in N2) was about 2 times faster than under 20 % CO2 (in N2), quite similar to wood gasification. In particular, an inhibitory effect between CO2 and H2O on reactivity during gasification in the mixed atmosphere was observed. Database and results from this study would provide useful information for the design or modeling of an efficient coffee husk gasifier.