Analyzing the pyrolysis kinetics of rice straw, bagasse, and mixtures thereof and product energy yield

Abstract

In Taiwan, rice straw and bagasse are major agricultural wastes that are produced in extremely large quantities and volumes and contain high moisture content. Current processing methods remain inadequate; therefore, this study focused on the pyrolysis and relevant analyses of rice straw, bagasse, and mixtures thereof to investigate the feasibility of copyrolyzing rice straw and bagasse for renewable energy generation. Mixtures containing various ratios of bagasse and rice straw were examined through physical, chemical, thermogravimetric, and reaction kinetics analyses. Pyrolysis experiments were conducted to investigate the energy yield of the reaction products. Both bagasse and rice straw contained low ash content, and thermal processing effectively reduced the waste volume and cost of final disposal. A mixture content containing approximately 30 wt% rice straw (potassium content reaching 8.50 g/kg) substantially reduced the activation energies required for copyrolysis reactions, subsequently reducing energies required for thermal processing. The solid char generated from pyrolyzing the bagasse and rice straw mixtures did not decay easily and exhibited high storability and transportability. Moreover, volumetric energy densities substantially increased after pyrolysis. Therefore, copyrolysis is arguably a feasible and effective alternative biofuel conversion method for countries that process large quantities of bagasse and rice straw.