Effect of Process Parameters on Hydrogen Production and Efficiency in Biomass Gasification Using Modelling Approach

Hydrogen is considered as an attractive clean fuel for the future. Hydrogen production via biomass steam gasification is receiving attention due to its sustainability and zero net carbon emission. Coupled with in-situ CO2 adsorption, this process has been proven to be environment friendly. The paper reports on the impact of temperature, steam/biomass ratio and sorbent/biomass ratio on hydrogen production performance in a steam gasification process using a simulation model developed in MATLAB. In this work, biomass is assumed as char, and gasification and CO2 adsorption occur in one gasifier. The model is used to predict the product gas composition, hydrogen yield and thermodynamic efficiency of the process. The results show that with the increase in temperature and steam/biomass ratio, the hydrogen concentration and yield increase, however the thermodynamic efficiency decreases. Hydrogen yield increases from 78 to 97 g/kg of biomass with the increase in temperature and steam/biomass ratio within the range of 800 to 1300 K and 2.0 to 5.0 respectively. Maximum hydrogen efficiency of 87 % is observed at 800 K and steam/biomass ratio of 2.0. At the sorbent/biomass of 1.52, hydrogen purity is predicted to reach 0.98 mole fraction with CO2 present in system absorbed. At 950 K with steam/biomass ratio of 3.0 and sorbent/biomass ratio of 1.0, a maximum hydrogen concentration of 0.81 mole fraction is obtained in the product gas. The steam feed rate is found to have the most impact on the hydrogen production and thermodynamic efficiency among the process parameters.