Simulation of steam gasification of halophyte biomass for syngas production using Aspen Plus

Abstract

Exploring the new non-edible source of biomass for green energy production becomes extremely important with the increase in global energy crises. The primary objective of this work is to evaluate the potential of halophyte (Phragmites australis), a salt-tolerant plant for syngas production, and provide it as a promising alternative biofuel for sustainable energy production. This study is based on the steady-state chemical equilibrium model simulation of steam gasification of halophyte biomass (Phragmites australis) with CO2 capture through sorbent (CaO) using ASPEN PLUS®. The simulation model works on the principle of Gibbs free energy minimization. The operating parameters such as temperature, steam to biomass ratio (STBR), and CaO/biomass ratio have been varied over a wide range. The effect of high heating value (HHV), low heating value (LHV), H2/CO, carbon conversion efficiency (CCE), and cold gas efficiency (CGE) has been investigated for syngas production. The results showed that with the increase of temperature from 600 to 700 °C, H2 concentration increased from 69.52 to 75.16 vol %, respectively. A reduction in CO2 concentration from 16.91 to 5.4 vol % is observed by increasing the CaO/biomass ratio from 0.1 to 0.9. It has been observed that the product gas hydrogen yield rises with increased temperature. At an optimum temperature of 700 °C with an STBR of 0.4 and CaO/biomass ratio of 1.42, the maximum hydrogen yield is 75.16 vol % with a minimum CO2 content of 5.4 vol %. At these optimum conditions, the values of HHV, LHV, CCE, and CGE are 13.32 MJ/Nm3, 15.20 MJ/Nm3, 42.91%, and 78.63%, respectively. In addition, the developed model is validated against published literature data, and the results show good agreement with the published data. The relative error for hydrogen and carbon monoxide is within limits, i.e., 3.02% and 0.67% at 700 °C, 5.30% and 3.61% at 600 °C, and 10.62% and 35.03% at 500 °C, respectively, which validates the proposed model. It can be concluded that the sorption-based biomass gasification process is a promising technique for greener syngas production.