Sensitivity Analysis and Parametric Optimization of Hydrogen Production from Afuze Coal through Air-Steam Gasification

Coal is a carbon-rich sedimentary rock and fossil fuel that accounts for over 60% of all economically recoverable primary sources of energy on earth. The burning of coal emits ∼40% of the entire energy-related atmospheric greenhouse gases, which poses risks to human health, safety, and the environment. Given this scenario, there are growing concerns about the long term sustainability of the industry vis-à-vis its effects on global warming and climate change. However, clean technologies such as gasification with carbon dioxide capture could be the panacea to the challenges of coal-fired electricity generation. Therefore, this study investigates the hydrogen (H2) and syngas potential of Afuze (AFZ) coal earmarked for electricity generation in Nigeria. Consequently, the mathematical simulation, sensitivity analysis, and optimization of AFZ were performed under air-steam gasification conditions using ASPEN Plus. Results revealed that AFZ gasification from 200°C to 1600°C and the feed rate of 1000 kg/h yields H2, CO, CO2 and CH4. The optimal conditions for H2 and syngas were observed at 950°C, ER = 0.31 and SC = 2.0 at the optimal gas compositions of H2 (48 mol.%), CO (11 mol.%), CO2 (11 mol.%) and CH4 (0 mol.%). Furthermore, temperature (T), equivalence ratio (ER), steam to carbon (SC) ratio greatly influenced AFZ gasification, whereas pressure did not impact the process. In conclusion, bench-scale or demonstration gasifier tests are required in future AFZ gasification studies to comprehensively investigate its energy recovery and electricity generation potentials.