Browsing by Author "Wilson, Lugano"

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    Advances in the HTAG Technology and Process of Biomass
    (Academic Journals, 2008) John, Geoffrey R.; Wilson, Lugano; Mhilu, Cuthbert F.
    High Temperature Air/Steam Gasification (HTAG) is a process in which a highly preheated air/steam is utilized as the oxidizer. The HTAG process follows the developments in the High Temperature Air Combustion (HiTAC), which has shown to be superior in energy saving and pollution reduction compared to the conventional combustion technology. The preheated oxidizer provides additional energy into the gasification process that enhances thermal decomposition of the gasified solid feedstock. Consequently, the HTAG increases both the calorific value of the producer gas, and the cold gasification efficiency. In this work, the advantages of the HTAG processes is presented by considering performance influencing parameters that include materials quality, oxidizer type, equivalence ratio (ER), gasification temperature, and bed additives.
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    Coffee Husks Gasification Using High Temperature Air/Steam Agent
    (Elsevier, 2010) Wilson, Lugano; John, Geoffrey R.; Mhilu, Cuthbert F.; Yang, Weihong; Blasiak, Wlodzimierz
    Analyses made on the world's biomass energy potential show that biomass energy is the most abundant sustainable renewable energy. The available technical biomass energy potential surpasses the total world's consumption levels of petroleum oils, coal and natural gas. In order to achieve a sustainable harnessing of the biomass energy potential and to increase its contribution to the world's primary energy consumption, there is therefore a need to develop and sustain contemporary technologies that increase the biomass-to-energy conversion. One such technology is the high temperature air/steam gasification (HTAG) of biomass. In this paper we present findings of gasification experimental studies that were conducted using coffee husks under high temperature conditions. The experiments were performed using a batch facility, which was maintained at three different gasification temperatures of 900 °C, 800 °C, and 700 °C. The study findings exhibited the positive influence of high temperature on increasing the gasification process. Chars left while gasifying at 800 °C and 700 °C were respectively 1.5 and 2.4 times that for the case of 900 °C. Furthermore, increased gasification temperature led to a linear increment of CO concentration in the syngas for all gasification conditions. The effect was more pronounced for the generally poorly performing gasification conditions of N2 and 2% oxygen concentration. When gasification temperature was increased from 700 °C to 900 °C the CO yield for the 2% O2 concentration increased by 6 times and that of N2 condition by 2.5 times. The respective increment for the 3% and 4% O2 conditions were only twofold. This study estimated the kinetic parameters for the coffee husks thermal degradation that exhibited a reaction mechanism of zero order with apparent activation energy of 161 kJ/mol and frequency factor of 3.89 × 104/min.