Process Design of Enriched Hydrogen Gas Production from Empty Fruit Bunch via Steam Gasification with In-Situ CO2 Capture

Due to the substantial production of palm oil in Malaysia, there is abundant availability of biomass in the form of agricultural wastes. Studies have shown that biomass steam gasification with in-situ carbon dioxide capture offers good prospects for the production of hydrogen rich gas. This work focuses on the mathematical modeling of the flowsheet design for hydrogen production from oil palm empty fruit bunch (EFB) using MATLAB. The process under focus is steam gasification with in-situ carbon dioxide capture by CaO. The flowsheet model incorporates the reaction kinetics models of the steam gasification of EFB (C3.4H4.1O3.3) and carbon dioxide adsorption, and the material balances. The developed model is used as a platform to investigate the effects of process parameters on the production of hydrogen rich gas from EFB using a single-pass fluidized bed gasifier; specifically the effects of temperature, steam/biomass ratio and sorbent/biomass ratio on the product gas composition, purity and yield of hydrogen in the product gas stream. Based on the results, the maximum hydrogen purity predicted is 71 mole% at 1150 K at outlet of the gasifier unit with the yield of 107.3 g/kg of EFB. The purity can be enhanced to 99.9 mole% using a filter, a scrubber and a pressure swing adsorption unit. The effect of steam/biomass ratio between 0.5 and 3.5 on the process performance is also reported, the hydrogen concentration and yield increase with respect to the steam/biomass ratio. It is observed that the increase in hydrogen yield is more significant when increasing the steam/biomass ratio compared to when increasing temperature, within the selected ranges. Meanwhile, by increasing the sorbent/biomass ratio, the purity of hydrogen increases, however showing less impact on the hydrogen yield. The mass conversion efficiency increases with increasing temperature and is found to be at the maximum at 84.7% at 1100 K. Moreover, the mass conversion efficiency increases by increasing steam/biomass ratio. The results are compared with published literature and showed good agreement. The study provides a useful simulation tool for the design and optimization of a future experimental work.