Air-Steam Gasification of Nigerian Lignite Coals for Hydrogen and Syngas Production

Abstract

Coal is the fuel that drives most emerging economies. The gasification along with carbon capture and sequestration could ameliorate the harmful effects of coal utilisation. In this study, two recently discovered lignite coals; Obomkpa (BMK) and Ihioma (IHM) were examined for hydrogen and synthesis gas production through air-steam gasification using a non-stoichiometric model simulated in ASPEN Plus. The results showed that H2 production from BMK and IHM was highly sensitive to temperature and air but moderately sensitive to steam during gasification. The optimal operating conditions for BMK and IHM are; temperature 1125 °C and 1350 °C; equivalence ratio (ER) 0.26 and 0.26; steam/carbon ratio (S/C) 2.25 and 2.19, respectively. The optimal gas composition for BMK was; H2 (0.66), CO (0.18) and CO2 (0.18) mole-fraction, whereas for IHM was; H2 (0.65), CO (0.17) and CO2 (0.17). The findings indicate that both lignite coals are suitable feedstock for H2 and syngas production.