Study on deposition tendency of coal ash under various gasification environments through DTF

Namkung, Hueon; Xu, Li-Hua; Shin, Wan Seon; Kang, Tae-Jin; Kim, Hyung-Taek

doi:10.1016/j.fuel.2013.07.028

Cited by 41 publications

(16 citation statements)

References 21 publications

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“…The weakened viscosity is unable to produce enough adhesion force that can prevent the fall-off of particles from the probe induced by the airflow collision or selfweight. As reported, the deposited ashes became heavier with the rise of probe temperature through a drop tube furnace [25], which was attributed to the higher viscosity of the ashes on the higher-temperature surfaces. A large amount of fine particles were adsorbed onto the surfaces of both the air-or water-cooled probes due to the temperature gradient (Fig.…”

Section: Microstructure and Crystalline Phase Of Depositssupporting

confidence: 54%

“…As reported, the ash richer in Ca, Fe and Mg melted more easily [25]. When approaching high-temperature surfaces, these elements formed surface-adhering eutectic compounds which then combined with the strongly affinitive S to form low-meltingtemperature sulfates.…”

Section: Property Changes Of Deposits Along the Gas Flow Directionmentioning

confidence: 55%

“…3b) and are covered with obvious melting as indicated by SEM image. EDX shows that large amounts of Ca, Si, Na, Fe and S are distributed on the slag surfaces, indicating these elements are fluxing materials [4,5,25,26]. The agglomerated and melted particles are primarily formed from eutectic compounds, silicates and (composite) sulfates, which reduce the melting point of deposits.…”

Section: Deposition Tendency At Different Wall Temperaturesmentioning

confidence: 99%

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Effects of wall temperature on slagging and ash deposition of Zhundong coal during circulating fluidized bed gasification

Song

et al. 2016

Applied Thermal Engineering

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Section: Microstructure and Crystalline Phase Of Depositssupporting

confidence: 54%

Section: Property Changes Of Deposits Along the Gas Flow Directionmentioning

confidence: 55%

Section: Deposition Tendency At Different Wall Temperaturesmentioning

confidence: 99%

See 1 more Smart Citation

Effects of wall temperature on slagging and ash deposition of Zhundong coal during circulating fluidized bed gasification

Song

et al. 2016

Applied Thermal Engineering

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“…Previous studies have shown that ash deposition rates depend on multiple factors, including flue gas velocity, ash composition, ash particle size, atmosphere, and operating temperatures [10][11][12]. Traditionally, the ash melting process is described by four temperatures: initial deformation temperature (IDT), softening temperature (ST), hemispherical temperature (HT), and flow temperature (FT) [13,14].…”

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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“…In other words, this indicates that ash minerals that include more Fe, Ca, and Mg can be melted more easily. Consequently, increasing the blending ratio leads to a high deposition growth rate [21]. In addition, Barroso et al [15] reported that the abundance of iron or calcium in low-rank coals results in lower viscosities of fly ash particles and an increased probability of deposition.…”

Section: Ash Depositmentioning

confidence: 99%

The effect of blending of bituminous and sub-bituminous coals on ash fusibility and deposition formation

et al. 2016

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Coal is an important energy source whose consumption increases continuously. One of the many ways to use coal is coal blending, which is a very effective technique in power stations. However, coal blending generates unsuspected problems, one of which is ash deposition that causes slagging and fouling. In fact, most blends accelerate and generate heavier ash depositions than their parent coals.This work investigates the characteristics of ash behavior including fusibility and deposition when blending both bituminous and subbituminous coals in a pulverized coal combustion. Two coals used in Japan were used for this study: bituminous (Bit-A) and subbituminous coal (Sub-A). In order to investigate, the blending ratio was changed. A Thermomechanical analysis (TMA) and a Drop tube furnace (DTF) were used for ash fusibility and deposit, respectively. Ash components were determined using X-ray fluorescence at the coal research center of Idemitsu Kosan Co., Ltd., in Japan. These tests revealed that as the blending ratio of Sub-A increased, fusibility in the TMA and the melting propensity increased. Capture efficiency and energy-based growth increased with the blending ratio, and were highest at 80%. Finally, a new approach based on the relation between ash fusibility and deposit derived for predicting adhesion tendency on blended coals was created by deriving the relation between the fusibility and deposit results that affected slag formation.

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Study on deposition tendency of coal ash under various gasification environments through DTF

Cited by 41 publications

References 21 publications

Effects of wall temperature on slagging and ash deposition of Zhundong coal during circulating fluidized bed gasification

Effects of wall temperature on slagging and ash deposition of Zhundong coal during circulating fluidized bed gasification

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

The effect of blending of bituminous and sub-bituminous coals on ash fusibility and deposition formation

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