Effect Of Pyrolysis Parameters On The Bio-Oil Production Yield From Cassava Peels

Abstract

Cassava peels (CP) constitute an important source of energy in the tropical region, are one of the most abundant agricultural residues, and have a high biofuel production potential. This thesis work investigates the effect of pyrolysis parameters on the bio-oil production yield from CP. The two principal objectives were to perform a comparative assessment of empirical methods of fast determination of lignocellulosic composition and predict numerically the pyrolysis byproduct yield using the detailed kinetic model of biomass pyrolysis. The results show that TGA data can be used for accurate determination of the lignocellulosic composition of biomass, the error between results from the chemical method data and TGA PKM method (±7%) lies in the range of error obtained from experimental chemical methods (±10%). Additionally, the empirical method of lignocellulosic composition based on elemental composition does not include all biomass samples. Therefore TGA-PKM method is an interesting option to have a good estimation of lignocellulosic fractions content. The quality of the fit between the DTG curves from the experiment and from the model for CP gave an R2 = 0.9765. The kinetics parameters were obtained by isoconversional methods based on thermal devolatilization behavior for four different heating rates: 5K/min, 15K/min 20K/min, and 30K/min. The mean value of activation energy using the KAS, FWO, and Friedman method was 224.87kJ/mol, 234.3kJ/mol, and 347.87kJ/mol respectively. Finally, the result from the investigation of pyrolysis conditions on bio-oil yield showed that the maximum bio-oil yield is obtained for the heating rate ranged between 80K/min to 100K/min. tacking into account the secondary reaction of tar, the vapor residence time affect negatively the bio-oil yield. An optimum pyrolysis temperature for maximum bio-oil yield is around 475°C. CP pyrolysis is not significantly affected by the particle size when the latter is less than 0.5mm since the temperature gradient between the surface and the center of the particle is less than 1°C.