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Energies 2017, 10(2), 242; doi:10.3390/en10020242

Effects of SiO2/Al2O3 Ratios on Sintering Characteristics of Synthetic Coal Ash

1
Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefei 230027, China
2
Anhui Civil Aviation Airport Group, Hefei 230086, China
*
Author to whom correspondence should be addressed.
Received: 1 December 2016 / Accepted: 14 February 2017 / Published: 16 February 2017
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Abstract

This article explores the effects of SiO2/Al2O3 ratios (S/A) on sintering characteristics and provides guidance for alleviating ash depositions in a large-scale circulation fluidized bed. Five synthetic coal ash (SCA) samples with different S/As were treated in a muffle furnace for 12 h at different temperatures (from 773 K to 1373 K, in 100 K intervals). The morphological and chemical results of the volume shrinkage ratio (VSR), thermal deformation analysis by dilatometer (DIL), scanning electron microscope (SEM), X-ray photoelectron spectrometer (XPS), and X-ray diffraction (XRD) were combined to describe the sintering characteristics of different samples. The results showed that the sintering procedure mainly occurred in the third sintering stage when the temperature was over 1273 K, accompanied with significant decreases in the VSR curve. Excess SiO2 (S/A = 4.5) resulted in a porous structure while excess Al2O3 (S/A = 0.5) brought out large aggregations. The other three samples (S/A = 1.5, 2.5, 3.5) are made up of an amorphous compacted structure and are composed of low fusion temperature materials (e.g., augite and wadsleysite.). Sintering temperatures first dramatically decrease to a low level and then gradually rise to a high level as S/A increases, suggesting that Al2O3-enriched additives are more effective than SiO2enriched additives in alleviating depositions. View Full-Text
Keywords: synthetic coal ash (SCA); sintering; dilatometer; eutectics synthetic coal ash (SCA); sintering; dilatometer; eutectics
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Hu, H.; Zhou, K.; Meng, K.; Song, L.; Lin, Q. Effects of SiO2/Al2O3 Ratios on Sintering Characteristics of Synthetic Coal Ash. Energies 2017, 10, 242.

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