Studies on Pyrolysis of Sugarcane Bagasse and Cashew Nut Shell for Liquid Fuels
Piyali Das, Ph.D, 04
Supervisor(s): Anuradda Ganesh
The fast pyrolysis of biomass is one of the most recent renewable energy processes, which offers the advantages of liquid product, bio oil, that can be used as potential fuel after modification. This liquid has a number of special features and characteristics, which negatively affect the fuel properties, like, high oxygen content, incompatibility with conventional fuels, heating value half that of hydrocarbon fuels, high viscosity causing difficulties in atomisation, low pH causing corrosion, and high instability due to polymerisation. The inorganic elements present in the ash are believed to be catalysing the polymerisation reactions and thereby increase the viscosity. The pretreatment of bagasse for deashing have taken up for the present study and investigated for the effect of deashing on product distribution and characteristics, specially on oil. Three different types of pretreatment, like water leaching, leaching with 5M HCl solution and with HF solution of different concentrations have been investigated. The study shows substantial increase in oil yield upon pretreatment. The leachates resulting from water leaching processes have also been found to be a potential source of ethanol, which in turn can be used for making the oil stable over time. Cashew nut shell (CNS), on the other hand, has been studied extensively for pyrolysis product distribution and oil characteristics. The total oil extracted from CNS accounts to more than 95\% of theoretical oil yield. The oil has unique characteristics unlike other pyrolysis oil, with a heating value of 40 MJ/kg, comparable to fuel oil and double to that of other pyrolysis oils. The unique structure found having long (C6-C15) linear chain as a head and phenolic group in the tail, in CNS oil, gives the excellent solubility in diesel, as well as in other biomass pyrolysis oils. The oil has an amazingly high stability at room temperature. A blending of high proportion of CNS oil / cardanol has been found to improve the properties like calorific value, viscosity and pH of bagasse pyrolysis oil, while the stability of the blend being taken care by addition of as low as 5 wt. % ethanol in combination.