Comparative studies and analysis on gasification of coconut shells and corn cobs in a perforated fixed bed downdraft reactor by admitting air through equally spaced conduits

Abstract

A 25 kWth, fixed, perforated bed, downdraft gasifier was used to investigate and compare its performance for using corn cob (CC) and coconut shell (CS) — a proven fuel for gasification as feedstocks. Air was used as a gasifying medium and had been administered inside the gasifier reaction zone (just above the throat) through four equally spaced conduits in forced circulation mode. Gas composition, higher heating value (HHV) of gas, specific gas generation (SGG), and gasification efficiencies had been compared for CC and CS by varying the equivalence ratios (ERs) from 0.1–0.45. HHV of gas generated upon the gasification was inferred to be maximum at an ER of 0.3 while using CC (4.578 MJ/m3) and that of 0.35 for using CS (4.229 MJ/m3) as feedstocks. SGG — associated with maximum HHV of gas — was observed to be 2.12 m3/kg and 3.05 m3/kg for CC and CS, respectively. Optimal cold gas efficiency was obtained at the best operating point, i.e., at ERs of 0.3 and 0.35 for CC (62.83%) and CS (72.74%) gasification, respectively. Tar contents of 1.3 g/m3 and 0.62 g/m3 and particulate matter contents of 0.355 g/m3 and 0.215 g/m3 were quantified for the producer gas generated from CC and CS gasification, respectively.