Thesis Archive
Kinetic Study of Carbon Dioxide Gasification of Philippine Rice Straw Blended with Philippine and Indonesian Coals
Ang, Camille Beatrice
Santos, Kevin Kyle B.
Abstract:
The potential of rice straw utilization for biomass coal co-gasification has been studied upon by various authors but has not been fully explored. Hence, complete feasibility of rice straw as a renewable resource and enhancer of coal gasification reactivity requires further investigation and study. In order to understand the applicability of rice straw for coal gasification enhancement, a kinetic study of co-gasification of a ternary blend consisting of RS, PH and IN was conducted. The kinetics of CO2 co-gasification of a mixture comprised of Philippine rice straws (RS), Philippine lignite (PH) and Indonesian (IN) sub-bituminous coals were investigated using a thermogravimetric analyzer (TGA) at temperatures of 700˚C, 800˚C and 900˚C. The gasification behavior of different blends of the carbonaceous materials were determined by lumped kinetic modelling. Four gas-solid reaction models were selected to predict the kinetic behavior of the experimental data which are the random pore model (RPM), shrinking core model, modified volumetric model (MVM) and extended modified volumetric model (EMVM). The experimental data were fitted in each kinetic model using Matlab Simulink and Microsoft Excel to determine their goodness of fit and the kinetic parameters of gasification. Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) were used to obtain a qualitative analysis of the char surface and a quantitative investigation of the mineral matter content and composition of the samples. Based from the analysis of the kinetic data, it was determined that both EMVM and MVM were equally the most suitable kinetic models to describe the CO2 co-gasification of chars derived from both the pure and blended samples. Enhancement of char reactivity was achieved at every RS + IN + PH blending ratio. This was attributed to the abundance of catalytic minerals within rice straw, scarcity of inhibiting minerals within Indonesian coals, developed char morphology and the high gasification temperatures. Overall analysis of the experimental data revealed that Philippine rice straws could indeed enhance the char reactivity of both Philippine lignite and Indonesian sub-bituminous coals within a ternary blend mixture. Dependence on purely additive catalysts and high temperature operation for the enhancement of coal reactivity could be mitigated through the integration of rice straw to local and imported low rank coal fuel blends.
Adviser:
Bungay, Vergel C.