Flowsheet Modelling of Biomass Steam Gasification System with CO2 Capture for Hydrogen Production

There exists high potential for hydrogen production in Malaysia from biomass due to abundant agriculture waste. Biomass steam gasification with in situ carbon dioxide capture has good prospects for the production of hydrogen rich gas. This work focuses on the mathematical modeling of the flowsheet design for hydrogen production from biomass via steam gasification with in situ carbon dioxide absorption by CaO, carried out using MATLAB. The effects of temperature, steam/biomass ratio and sorbent on the purity and yield of hydrogen in the product gas stream are predicted using the model. Based on the results, the maximum hydrogen purity predicted is 0.81 mole fraction at 950 K at outlet of the gasifier unit and it can be enhanced to 99.99 % using a scrubber and a pressure swing adsorption unit. At 950 K with steam/biomass ratio 3.0 and sorbent/biomass ratio, the hydrogen yield obtained 95.40 g/kg of biomass. Between the temperature range of 800 to 1300 K, hydrogen yield is predicted to increase from 76.5 to 97.3 g/kg of biomass. It is observed that the increase in hydrogen yield is larger when increasing the steam/biomass ratio compared to when increasing temperature, within the selected ranges. The mass conversion efficiency (MCE) showed linear co relation with temperature. The results are compared with the literature and show good agreement.