Pyrolysis and Char Oxidation of Biomass and Coal Blends: Kinetic Study Using Thermogravimetric Analysis

Vietnam as an agricultural country has a high potential in biomass, especially agricultural and forestry wastes. This resource offers a promising way to develop co – combustion technology of biomass and coal in Vietnam and thus tackle the environmental issues. A fundamental research was established to study combustion of Vietnamese rice straw and coal. Blends was made by mixing manually 50% wt. of rice straw and 50% wt. of coal. Pyrolysis in inert gas, char oxidation in oxidizing gases (10 % O₂ in N₂) and combustion process in oxidizing gases (10 % O₂ in N₂) were implemented. A particular attention was paid to the behaviour of rice straw/coal blends during thermochemical transformation. Concerning pyrolysis process, the char yield of the mixture is equivalent to weighted sum of the char yield of two solid fuels. During the combustion of the blends, we observed a coupling between pyrolysis and char oxidation. The exothermic oxidation reactions could overheat the sample itself and accelerate the pyrolysis and char oxidation kinetics.