Browsing by Author "Vincent, Shubha Shalini"

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    Investigation of Torrefaction Process Parameters on Biomass Feed-Stock and CO2 Gasification of Torrefied and Pyrolysed Bio-char
    (2013-10-02) Vincent, Shubha Shalini; Mahinpey, Dr.Nader
    Torrefaction is a thermo-chemical process, carried out at a relatively low temperature ranging from 200-300°C. This research focuses on torrefaction of flax straw at laboratory scale. A Thermo Gravimetric Analyzer (TGA) was used to study the effect of temperature, particle size and residence time on the torrefaction of flax straw. Proximate analysis of the char showed a significant increase in fixed carbon and ash content, and a noticeable decrease in the moisture and volatile content with an increase in the temperature. Ultimate analysis was performed for the product char and from these results heating value of the torrefied char was calculated. The kinetic analysis showed an activation energy of 76.64 kJ mol-1, for the particle size of 925 µm. The experimental results of the torrefaction of flax straw indicated that the temperature had greater effect on torrefaction process than the residence time and the particle size’s chosen for this study. CO2 gasification of flax straw char produced by two different processes namely torrefaction and pyrolysis was investigated using a TGA. The objective of this research was to investigate the diffusion and surface reactions that occur during the CO2 gasification of the torrefied and pyrolysed char particles. Gasification experiments were carried out at four different temperature range from 750 to 900ᵒC and at different particle sizes (<90 µm to 925 µm). The effects of temperatures, particle sizes, and the char types on the rate of CO2 gasification process were determined. The reactivity of the char particles at 50% conversion showed an increase in the reactivity values with a corresponding increase in the temperature and decreased with an increase in the particle sizes for both the char types. The diffusional parameters such as effective diffusivity, effectiveness factor, and Diffusion limitation index (DLI) were calculated from the experimental data for both the char types.