Modeling and simulation of pine sawdust gasification considering gas mixture reflux

Abstract

In this study, a comprehensive model was developed by Aspen Plus software to simulate the pine sawdust gasification process on the basis of the Gibbs free energy minimization method. The accuracy of this model was validated by experimental data and another model. In addition, the computational experiments were carried out. The influence of temperature, equivalence ratio (ER), steam to biomass ratio (S/B) and the reflux ratio of gas mixture on the gas composition, heating value and the carbon conversion efficiency was investigated. Results showed that the predicted values were in good agreement with experimental data. The root means square error (RMSE) of each gas composition except methane ranged from 3.72 % to 8.30 % when varying gasification temperature and also ranged from 2.75 % to 9.11 % when varying steam to biomass ratio, and values of methane were both below 20 %. As for the influence of parameters, temperature had a significant effect on biomass gasification. The increase of this parameter not only can enhance the carbon conversion efficiency and the production of H2, but inhibit the generation of CO and CH4. In addition, equivalence ratio was directly proportional to the carbon conversion efficiency and the molar fraction of CO and CO2. The effect of steam to biomass ratio was similar with that of temperature. And the reflux operation of gas mixture could promote the gaseous products’ quality by promoting the generation of CO and reducing the molar fraction of CO2.