The sintering behavior of coal ash under pressurized conditions

Jing, Nijie; Wang, Qinhui; Cheng, Leming; Luo, Zhongyang; Cen, Kefa

doi:10.1016/j.fuel.2011.09.025

Cited by 20 publications

(11 citation statements)

References 20 publications

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“…It has been concluded that high SiO 2 /Al 2 O 3 ratios (S/As) and low concentrations of basic oxides account for the high ash fusion temperatures of most Australian bituminous coal ashes [23]. Recent related literature has established ash chemical compositions under either an oxidizing atmosphere or a reductive atmosphere, based on Jincheng coal, Xiaolongtan (XLT), and Huolinhe (HLH) coal, respectively [24,25]. However, the complex chemical compositions of industrial coal ashes bring obstacles in quantitatively exploring the role of individual components.…”

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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“…Besides, from the EDS analysis on the melting surface, the chosen spot mainly contained O, Si, K and Ca. The K and Ca elements are easy to form some low temperature eutectics,14 which explained why high content of K and Ca presented on the melting surface.…”

Section: Resultsmentioning

confidence: 97%

“…The ash sintering behavior is mainly controlled by the chemistry of the ash and other factors such as atmosphere, temperature, and particle size 7. 13, 14 Jing et al 15. observed that the addition of CaO or NaO can significantly reduce the sintering temperatures of ash produced under both combustion and gasification atmosphere conditions.…”

Section: Introductionmentioning

confidence: 99%

Ash Sintering Behavior of Lignite in Catalyzed Steam Gasification with Kaolin as Additive

Zhang

Yang

et al. 2015

Energy Tech

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An investigation of the ash sintering characteristics of LLI lignite with kaolin additive during K2CO3‐catalyzed steam gasification was conducted in this study. The ash samples were prepared using a catalytic gasification system at 1073 K under steam atmosphere. Experiments on the sintering behavior were performed using a pressure‐drop sintering device under inert N2. Results showed that when increasing the concentration of K2CO3 from 0 to 10 wt %, the ash sintering temperature decreased and the ash molten degree become more serious. The potassium‐containing compounds arcanite and kaliophilite can trigger the occurrence of sintering on reactions with other minerals to facilitate the formation of liquid phases and then result in a lower ash sintering temperature. Besides, kaolin can increase ash sintering temperature and ease the melt degree of ashes. Kaolin can react with other minerals to generate more refractory silicon oxide and decrease the fluxing arcanite and amorphous materials in ashes.

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“…During gasification and combustion process, these minerals are transformed into other new mineral matters by a series of complicated physical and chemical reactions, which can affect the sintering strength, the slagging tendency and other properties of coal char and ash. Jing and her coworkers [9,10] investigated the sintering behaviors of ash at elevated pressure and found that the mineral transformations of coal ash can be affected by the pressure, which in turn influenced the sintering temperature. Moreover, Jing et al [11] studied the impact of pressure on the fusibility of ash and concluded that the interactions among different mineral matters were also dependent on the reaction atmosphere at elevated pressure.…”

Section: Introductionmentioning

confidence: 99%

Investigation on the physicochemical properties of coal char during pressurized pyrolysis and the mineral transformations of coal ash during pressurized O₂/N₂ and O₂/CO₂ combustion

Lei

Sun

Zhang

2020

Intl J of Energy Research

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Physicochemical properties of coal char during pressurized pyrolysis and the mineral transformations of coal ash during pressurized O 2 /N 2 and O 2 /CO 2 combustion were investigated by a pressurized tube furnace with Fourier transform infrared spectroscopy and X-ray diffraction analysis. The results indicated that as the pyrolysis pressure increased, the decompositions of the aromatic ring structure and the hydroxyl hydrogen bonds of char were enhanced and the aromatic ring transformed to the low-substituted single ring.Meanwhile, the aliphatic chain and carboxyl group in the char shortened at elevated pressures. Furthermore, pressurized pyrolysis increased the degree of graphitization of the char, which further influenced the microcrystalline parameters of char. During the pyrolysis process, the decompositions of some low-temperature minerals in the char were inhibited by the elevated pressure. In addition, the effect of the furnace temperature on the mineral transformations of char was more significant than the effect of the furnace pressure. Compared to what observed at atmospheric pressure, the primary minerals in the coal ash remained the same at elevated pressure, but their relative contents changed to some extent. And, the influence of the furnace pressure on the transformations of minerals in the ash was mainly affected by the combustion temperatures of different ignition mechanisms at different pressures. Compared to the O 2 /N 2 mixture, the decompositions of low-temperature minerals and the formations of high-temperature minerals were restrained due to the relatively low combustion temperature in the O 2 /CO 2 mixture. And, the furnace temperature instead of the furnace pressure was the primary factor which influenced the mineral transformations of ash.

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The sintering behavior of coal ash under pressurized conditions

Cited by 20 publications

References 20 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

Ash Sintering Behavior of Lignite in Catalyzed Steam Gasification with Kaolin as Additive

Investigation on the physicochemical properties of coal char during pressurized pyrolysis and the mineral transformations of coal ash during pressurized O₂/N₂ and O₂/CO₂ combustion

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The sintering behavior of coal ash under pressurized conditions

Cited by 20 publications

References 20 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

Ash Sintering Behavior of Lignite in Catalyzed Steam Gasification with Kaolin as Additive

Investigation on the physicochemical properties of coal char during pressurized pyrolysis and the mineral transformations of coal ash during pressurized O2/N2 and O2/CO2 combustion

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Investigation on the physicochemical properties of coal char during pressurized pyrolysis and the mineral transformations of coal ash during pressurized O₂/N₂ and O₂/CO₂ combustion