Investigation of Coal Fueled Chemical Looping Combustion Using Fe_3O_4 as Oxygen Carrier:Influence of Variables

Chemical-looping combustion (CLC) is a novel combustion technique with inherent CO2 separation.Magnetite (Fe3O4) was selected as the oxygen carrier.Shenhua coal (Inner Mongolia,China),straw coke and natural coke were used as fuels for this study.Influences of operation temperatures,coal to Fe3O4 mass ratios,and different kinds of fuels on the reduction characteristics of the oxygen carrier were investigated using an atmosphere thermogravimetric analyzer (TGA).Scanning electron microscopy (SEM) was used to analyse the characteristic of the solid residues.Experimental results shown that the reaction between the coal and the oxygen carrier become strong at a temperature of higher than 800℃.As the operation temperature rises,the reduction conversion rate increases.At the temperatures of 850oС,900℃,and 950℃,the reduction conversion rates were 37.1%,46.5%,and 54.1% respectively.However,SEM images show that at the temperature of higher than 950℃,the iron oxides become melted and sintered.The possible operation temperature should be kept around 900℃.When the mass ratios of coal to Fe3O4 were 5/95,10/90,15/85,and 20/80,the reduction conversion rates were 29.5%,40.8%,46.5%,and 46.6% respectively.With the increase of coal,the conversion rate goes up.But there exist an optimal ratio around 15/85.Comparisons based on different kinds of fuels show that the solid fuel with a higher volatile and a more developed pore structure is conducive to the reduction reactivity of the oxygen carrier.

Energy and Exergy Analysis of a Novel Efficient Combined Process by Hydrothermal Degradation and Superheated Steam Drying of Degradable Organic Wastes

This paper considers the combination of hydrothermal degradation （HTD） and superheated steam （SHS） drying in disposal and processing of degradable organic wastes in municipal solid wastes （MSW）. In SHS drying, a fraction of dryer thermal energy input can be recovered and used to satisfy the heat requirement in maintaining the HTD operating temperature. Both energy and exergy analysis are applied to the combined process. The analysis covers ranges of dryer inlet temperatures of 202.38-234.19~C and feed water content of 32.5-65%. Thermal energy analysis shows that the combination of HTD and SHS drying can achieve thermal energy self-sufficiency （TES） by manipulating process variables. The exergy analysis indicates the location, type, and magnitude of the exergy losses during the whole process by applying the second law of thermodynamics.

Highly efficient ultraviolet high-harmonic generation from epsilon-near-zero indium tin oxide films

High-harmonic generation in the ultraviolet region is promising for wireless technology used for communications and sensing. However, small high-order nonlinear coefficients prevent us from obtaining high conversion efficiency and functional photonic devices. Here, we show highly efficient ultraviolet harmonic generation extending to the fifth order directly from an epsilon-near-zero indium tin oxide(ITO) film. The real part of the annealed ITO films was designed to reach zero around 1050 nm, matching with the central wavelength of an Yb-based fiber laser, and the internal driving electric field was extremely enhanced. A high energy conversion efficiency of 10-4 and 10-6 for 257.5 nm(fourth-order) and 206 nm(fifth-order) ultraviolet harmonic generation was obtained,which is at least 2 orders of magnitude higher than early reports. Our results demonstrate a new route for overcoming the inefficiency problem and open up the possibilities of compact solid-state high-harmonic generation sources at nanoscale.