Studies on Pyro-Oil and Pyro-Gas derived from Lignocellulosic wastes

Abstract

Abstract Pyrolysis of lignocellulosic biomass stands out as one of the most promising thermochemical processes to generate energy from waste. This thesis focuses on using experimental and theoretical methods to study the pyrolysis of jute packaging waste and lime waste along with the development of kinetic and process simulation models and energy and environmental analysis. As the key experimental platform, a semi-batch pyrolyzer was first developed to study the kinetics of non-catalytic and catalytic pyrolysis of jute and lime wastes. The effects of different catalysts on the pyrolysis of waste jute and lime waste have been studied and the best performing catalysts have been selected. Reaction kinetics of catalytic and non-catalytic pyrolysis of jute and lime waste have been determined using both lumped and DAE models. For the further application in scaling –up from the first principle of mass and energy balance, a deterministic mathematical model, based on the parameters determined using lumped kinetics, has been developed and validated for a lab-scale (Φ50mm x 640mm) cylindrical semibatch pyrolyzer using waste jute as the feedstock. To extend the scope of simultaneously using multiple feed-stocks, co-pyrolysis of jute waste and sesame oil cake have been studied. All the pyro-products, namely pyro-char, pyro-oil and pyro-gas have been analyzed using sophisticated instruments and have been observed to have great potential as energy and chemical resources. To assess the further scope for utilization of pyro-products, the parameters for lumped kinetics have also been determined for the thermal decomposition of the pyro-oil obtained at different pyrolysis temperature. The potential of the pyro-gas for the conversion to liquid fuel through Fischer Tropsch process has also been assessed for the 100 tpd pyrolysis plant. Sensitivity analysis using Response Surface Methodology (RSM) has been done using the production rates of diesel and gasoline from the FT process as the response variables and the recycle ratio of CO2 ( CO2 R ) and pyrolysis temperature (T) as the factors. Process simulation model using Aspen Plus ® has been developed for large scale (100 tpd) pyrolysis plant of jute waste to assess the scalability of the process. Ultimately an assessment of energy efficiency and environmental impact of the large pyrolysis plant has been made by clearly specifying the goal and scope of utilization of the pyro-products using Aspen Plus ®. The sensitivity analysis has been done to maximize CO2 avoidance ( CO2 A ) and Energy Return on Energy Investment (EROEI) using RSM technique.