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Although numerous studies on CO2 gasification during coal char combustion have been documented, the effects of CO2 gasification on high-temperature carbon oxidation, which is important for evaluation of carbon conversion during pulverized coal combustion under oxy-fuel and flue gas recirculation conditions, are unclear. Thus, the char conversion characteristics at various contents of O2 and CO2 were...
The main components in bio-oil behave differently during the thermal treatment in water or in methanol. Water cannot stabilize the aromatics in bio-oil. Consumption of the aromatics with mono-ring and two fused benzene rings and the formation of the aromatics with three or more fused benzene ring aromatics were observed during the thermal treatment in water. In methanol, the fluorescence intensities...
The sorption-enhanced glycerol steam reforming (SE-GSR) provides a promising high-efficient means for hydrogen production. Fluidized bed reactors have their own potential on the heat transfer and sorbent regeneration. To gain a deep insight into the SE-GSR process in fluidized bed reactors, a computational fluid dynamics (CFD) approach is employed in this study. The multi-fluid model is implemented...
Lignite is well known for its hard-to-float property. Many surfactants, including anionic, cationic and non-ionic have been applied to improve the floatation efficiency. In this work, cationic dodecylamine was applied to pretreat the lignite samples with different densities, which are −1.45 g/cm3, 1.45–1.80 g/cm3 and +1.80 g/cm3. The surface charged properties of the raw samples were determined by...
This study aims to investigate the changes in char structure during the pyrolysis in N2 and subsequent gasification in air at low temperature in a thermogravimetric analyser. The chars produced from the gasification of Loy Yang brown coal in 15% H2O balanced with CO2 at 850 °C in a fluidised-bed/fixed-bed reactor were used in this work. The evolution of char structure during pyrolysis and in-situ...
The different catalytic behaviour of solid acid catalyst and mineral acid catalyst towards the acid-treatment of bio-oil was investigated. The hydrogen ions in the mineral acid catalyst such as sulfuric acid homogeneously dispersed in the reaction medium made the conversion of main components of bio-oil including carboxylic acids, sugars and phenolics more efficient. In comparison, there was a steric...
This study aims to investigate the structural features of nascent char. Two nascent chars were prepared from the pyrolysis of Loy Yang brown coal and Collie sub-bituminous coal in a wire-mesh reactor by heating at 1000Ks−1 to 600°C. Structural changes in nascent chars were investigated by reheating the chars in N2 at low temperatures (≤600°C) followed by subsequent gasification in O2/N2 mixtures at...
This study is focused on the effects of char structure and alkali and alkaline earth metallic (AAEM) species on the changes in char-O2 reactivity for a Western Australian Collie sub-bituminous coal. The char samples used in this study were acquired from the partial gasification of the sub-bituminous coal in a fluidised-bed/fixed-bed reactor in pure CO2, 15% H2O balanced with Ar and a mixture of 15%...
Complex interactions among components in the heterogeneous grinding have an influence on breakage and energy consumption characteristics of components in mixtures if compared with the single breakage. In this paper, a modified Hardgrove mill, with the addition of a power meter, is used to simulate the grinding process of vertical spindle pulverizer. Binary-component mixtures of coal and pyrite, or...
The second-order moment (SOM) method is developed to describe the fluctuating anisotropy of particles in coal combustion process. Large-eddy simulation (LES) is employed for turbulence of gas phase. The LES-SOM model is coupled with chemical kinetics for coal combustion simulations and the anisotropy characteristic of particles is analyzed in circulating fluidized bed (CFB). The simulation results...
In order to investigate the classification performance of static air classifier in an industrial Vertical Spindle Mill (VSM), sampling ports were drilled on the mill shell and new on-line sampling methods were designed. Size and density compositions of classifier feed, classifier reject and Pulverized Fuel (PF) were analyzed. Calculation was done about the circulating ratio within the VSM and classification...
Potassium-based carbonate looping in a circulating fluidized bed system including an absorber and a regenerator is a potential CO2 capture technology, which has attracted great focus in recent years. In the current work, the simulation of CO2 capture process is carried out by considering the influence of clusters on the hydrodynamic and reaction, where the multiscale reaction model is employed to...
The purpose of this study is to investigate the structural changes in nascent chars during the gasification of two low-rank coals in CO2 at 1000°C and 1200°C. Western Australian Collie sub-bituminous coal and Victorian Loy Yang brown coal were heated up at 1000Ks−1 in He/CO2 in a wire-mesh reactor. FT-Raman spectroscopy was applied to understand the key structural features of nascent chars. For comparison,...
In this study, acid-catalyzed conversions of three typical C6 sugar monomers/oligomers (glucose, maltose, and beta-cyclodextrins) to levulinic acid in water, tetrahydrofuran (THF) and toluene have been investigated over a solid acid catalyst Amberlyst 70 (A70), aiming to understand behaviors of the sugars in the solvents with distinct polarities. Molecular sizes of the sugars do not affect both insoluble...
How a catalyst would speed up gasification is fundamentally important for the development of efficient gasification technologies. It is particularly crucial for the efficient use of catalytic species inherently present in low-rank coal and biomass. This study aims to gain insights about the catalytic gasification reaction mechanisms through tracing the changes in char structure during gasification...
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