Renewable energy is the key to meet the ever-increasing global energy needs in a climate-constrained world. Biomass, being the only carbon based renewable energy fuel, is gaining importance in order to satisfy environmental concerns about fossil fuel usage. Biomass co-firing with coal is one of the main methods in achieving the objectives of increasing sustainable energy production. The present paper is aimed at the development of a computational model for biomass pyrolysis and combustion in a compressible gas flow