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(321a) Gasification of Organic Solid Waste Under High-Flux Solar Irradiation: Thermodynamics, Kinetics, and Fixed-Bed Reactor Evaluation

Authors: 
Wang, C. H., National University of Singapore
Li, X., National University of Singapore
Shen, Y., National University of Singapore
Lipinski, W., The Australian National University
Dai, Y., Shanghai Jiaotong University
Conventional autothermal gasification processes are driven by heat derived from combustion of a portion of feedstock. Combustion generates byproducts, which contaminate the product synthesis gas (syngas) ‒ a mixture mainly consisting of H2 and CO. The advantages of solar-driven gasification as a means of upgrading carbonaceous feedstocks to syngas were demonstrated in prior work in the field. Here, we present a study of solar thermal dry gasification of organic waste including thermodynamics, chemical kinetics and design, fabrication and evaluation of a 2 kWth fixed-bed CO2 gasifier. Thermodynamic analyses were conducted to explore theoretical efficiency and composition limits of the process. Chemical kinetics of CO2 gasification were investigated by employing thermogravimetric analysis with selected types of carbonaceous feedstocks including waste wood and sewage sludge. The high-flux solar irradiation tests were performed with a windowless solar gasifier with two concentric silicon carbine cavities: the inner cavity serving as a solar receiver to absorb high-flux solar irradiation and the outer cavity serving as a reactor chamber for gasification. The gasifier tests were performed under simulated sunlight provided by a new multi-source high-flux solar simulator developed at National University of Singapore. The solar flux distribution in the reactor aperture plane was measured by a water-cooled thermogage heat flux sensor and a CCD camera. The effects of CO2/C ratio and input solar power to the reactor on the carbon conversion, cold gas efficiency, and solar-to-fuel efficiency were experimentally explored.