Optimization of process parameters in oxygen enriched combustion of biocoal and soma lignite blends by response surface methodology

•Central Composite Designs (CCD) of two factors is selected to obtain the optimal conditions for the oxy-combustion of a biocoal / Soma Lignite blends.•The proportion of biocoal in the fuel blend is the most effective parameter among the five responses.•Optimum operational conditions have been obtained for the combustion of biochar with Soma lignite by producing less emissions at the outlet.