Process modelling and thermodynamic performance optimization of mixed Indian lignocellulosic waste co-gasification

Bio-syngas derived from lignocellulosic biomass (LB) has emerged as a potential precursor gas to be converted to liquid fuels. The quality of syngas with respect to the concentrations of CO, H2 and CO2 is, however, dependent on the elemental analysis of the LB and the variables like equivalence ratio, gasification temperature. The generation of tar and ash from the gasification process is also influenced by the proximate analysis of the LBs. In this study, steady state process simulation of co-gasification of mixed Indian LBs has been developed through Aspen plus using non-equilibrium model based on reaction kinetics. Formation of char and tar has also been incorporated in the model. The composition of syngas, obtained through Aspen plus simulation of co-gasification has been successfully compared with literature data. The ratio between individual agro wastes in the LB mixture is another input variable in the co-gasification model. Finally, response surface methodology has been used to optimise the energy and exergy efficiency of the co-gasification process with respect to equivalence ratio, gasification temperature and ratio of high and low ash LBs. It has been found that the combination of 750°C temperature, 0.2 biomass ratio and 0.2 equivalence ratio gives the optimum energy efficiency and combination of 750°C temperature, 0.8 biomass ratio and 0.5 equivalence ratio gives maximum exergy efficiency. © 2020 John Wiley & Sons Ltd