Comparative exergetic performance analysis of hydrogen production from oil palm wastes and some other biomasses

Abstract

In this study, we investigate the exergetic performance assessment of hydrogen production from gasification of various biomasses, including oil palm. We employ the operational and energy data as taken from the literature for two different gasifier samples of oil palm biomasses. The first one is a steam gasification of oil palm wastes over supported tri-metallic catalyst. We calculate the specific exergies for shell, fiber and empty fruit bunches (EFB) as 22.7, 21.1 and 20.03 MJ/kg, respectively. Based on these, with no catalyst, calcined dolomite and tri-metallic catalyst cases, hydrogen contents of syngas change from 36.5 to 53.6 (%v/v). We then calculate the specific exergy values of these syngases to be 14.59, 16.65 and 15.15 MJ/kg with no catalyst, calcined dolomite and tri-metallic catalyst, cases, respectively. The second one is done by air gasification in a fluidized bed reactor of EFB. For the two samples considered, we investigate the effects of some operational parameters such as gasification temperatures, catalytic bed temperatures, steam biomass ratio (SBR), equivalence ratio (ER) and particle size, to hydrogen and combustible gas contents, specific exergy values and exergy efficiencies. Finally, the performance results of EFB are compared with six different biomass fuels, namely almond shell (ASF), walnut pruning (WPF), rice straw (RSF), whole tree wood chips (WWF), sludge (SLF) and non-recyclable waste paper (NPF). The specific exergy values of the syngasses and exergy efficiencies for the six biomasses change from 4.07 to 6.95 MJ/kg and from 25.73% to 55.4% as compared to 12.35 MJ/kg and 61.66% for EFB.