Influence of Coal Blending on Ash Fusibility in  Reducing Atmosphere

Mingke, Shen; Qiu, Kunzan; Zhang, Long; Huang, Zhenyu; Wang, Zhihua; Liu, Jianzhong

doi:10.3390/en8064735

Cited by 26 publications

(21 citation statements)

References 33 publications

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“…Ash depositions formed at various ash fusion temperatures always differ in chemical composition. Researchers have established that ash deposition can be alleviated by changing chemical compositions through blending ash with proper additives [5][6][7][8][9]. Therefore, it is important to investigate the relationship between ash fusion temperatures and chemical compositions in order to better understand the deposition mechanism and the necessary operational adjustments.…”

Section: Introductionmentioning

confidence: 99%

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

Zhou

Meng

et al. 2017

Energies

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This article explores the effects of SiO 2 /Al 2 O 3 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 SiO 2 (S/A = 4.5) resulted in a porous structure while excess Al 2 O 3 (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 Al 2 O 3 -enriched additives are more effective than SiO 2 -enriched additives in alleviating depositions.

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Section: Introductionmentioning

confidence: 99%

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

Zhou

Meng

et al. 2017

Energies

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“…As stated, the existence of zoisite and Ca 2 SiO 4 in MF/HA samples forecasts the possibility of sintering reaction during sintering processing. In addition to the reactions at 1150 °C, the formation process of the new phase could be described by the following reaction [ 24 ]: 4CaO + 3Al 2 O 3 ·2SiO 2 = 2Ca 2 SiO 4 + 3Al 2 O 3 …”

Section: Resultsmentioning

confidence: 99%

Sintering Behavior and Mechanical Properties of Mullite Fibers/Hydroxyapatite Ceramic

et al. 2018

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The effect of fiber content and sintering temperature on sintering behavior and mechanical properties of mullite fibers/hydroxyapatite composites was studied. The composites were fabricated by hydrothermal synthesis and pressureless sintering. The amount of fibers was varied from 5 wt % to 15 wt % through hydrothermal synthesis, mullite fibers and hydroxyapatite composite powders were subsequently sintered at temperatures of 1150, 1250, and 1350 °C. The composites presented a more perturbed structure by increasing fiber content. Moreover, the composites experienced pore coalescence and exhibited a dense microstructure at elevated temperature. X-ray diffraction indicated that the composites underwent various chemical reactions and generated silicate glasses. The generation of silicate glasses increased the driving force of particle rearrangement and decreased the number of pores, which promoted densification of the composites. Densification typically leads to increased hardness and bending strength. The study proposes a densification mechanism and opens new insights into the sintering properties of these materials.

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“…The dehydroxylation products will contribute to the solid-state reactions of ash particles. (3) For SH coal with a low ash melting point, increasing the DTF temperature had a more significantly positive impact on the production of high-NBO/T matter in the ash of light coal compared to in Energies 2016, 9, 428 13 of 14 the ash of raw coal. In utility boiler furnaces, the clay minerals in light coal will play an important role in the occurrence of slagging.…”

Section: Discussionmentioning

confidence: 99%

“…Recent experimental research on ash depositions has shown the importance of determining aluminosilicate components in ash to understand the slagging mechanism of coal blend combustion [3,15,17]. Clay minerals, classified as phyllosilicates, constitute much of the inorganic matter in coal and are the source of aluminosilicates in fly ash [1,2,4,14].…”

Section: Introductionmentioning

confidence: 99%

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Distribution of Clay Minerals in Light Coal Fractions and the Thermal Reaction Products of These Clay Minerals during Combustion in a Drop Tube Furnace

et al. 2016

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Abstract:To estimate the contribution of clay minerals in light coal fractions to ash deposition in furnaces, we investigated their distribution and thermal reaction products. The light fractions of two Chinese coals were prepared using a 1.5 g¨cm´3 ZnCl 2 solution as a density separation medium and were burned in a drop-tube furnace (DTF). The mineral matter in each of the light coal fractions was compared to that of the relevant raw coal. The DTF ash from light coal fractions was analysed using hydrochloric acid separation. The acid-soluble aluminium fractions of DTF ash samples were used to determine changes in the amorphous aluminosilicate products with increasing combustion temperature. The results show that the clay mineral contents in the mineral matter of both light coal fractions were higher than those in the respective raw coals. For the coal with a high ash melting point, clay minerals in the light coal fraction thermally transformed more dehydroxylation products compared with those in the raw coal, possibly contributing to solid-state reactions of ash particles. For the coal with a low ash melting point, clay minerals in the light coal fraction produced more easily-slagging material compared with those in the raw coal, playing an important role in the occurrence of slagging. Additionally, ferrous oxide often produces low-melting substances in coal ash. Due to the similarities of zinc oxide and ferrous oxide in silicate reactions, we also investigated the interactions of clay minerals in light coal fractions with zinc oxide introduced by a zinc chloride solution. The extraneous zinc oxide could react, to a small extent, with clay minerals in the coal during DTF combustion.

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Influence of Coal Blending on Ash Fusibility in Reducing Atmosphere

Cited by 26 publications

References 33 publications

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

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

Sintering Behavior and Mechanical Properties of Mullite Fibers/Hydroxyapatite Ceramic

Distribution of Clay Minerals in Light Coal Fractions and the Thermal Reaction Products of These Clay Minerals during Combustion in a Drop Tube Furnace

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