Iron transformation behavior in coal ash slag in the entrained flow gasifier and the application for Yanzhou coal

He, Chao; Bai, Jin; Li, Weicheng; Kong, Lingxue; Xu, Jiang; Guhl, Stefan; Li, Xiaoming; Bai, Zongqing; Li, Wen

doi:10.1016/j.fuel.2018.09.134

Cited by 39 publications

(18 citation statements)

References 29 publications

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“…The ratio Fe 3+ /Fe 2+ increases with the iron content from S1 to S5. This is in accordance with He, 21 i.e., a higher increase of Fe 3+ than Fe 2+ as the iron level is increased.…”

Section: Methodssupporting

confidence: 88%

Different Roles of Iron Species in the Network Structure and Viscosity of Silicate Melts

Wang

Guhl

et al. 2020

Energy Fuels

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In iron-containing silicate melts such as gasification slags and geological slags, iron can play a different role in the melt properties because of its varying valence states. In this paper, the structural characteristics and viscosities of five samples were studied by molecular dynamics simulation and thermodynamic calculation methods. The effect of different iron species on the structure and properties is revealed. More than half of the Fe 3+ ions are in four-coordination. The four-and fivefold coordinated ferric ions are in dynamic equilibrium. The four-coordinated Fe 3+ can connect with the other tetrahedrons centered by Si 4+ and Al 3+ or integrate into three-coordinated oxygen units. With an increase of the iron content, the polymerization degree characterized by nonbridged oxygen per tetrahedra (NBO/T) is found to be inconsistent with the trend of viscosity. Based on the energy of the different types of oxygen, a new parameter RS total is proposed to substitute the original NBO/T and correlate with viscosity in an exponential function. Liquid iron can form in molten slags under a strong reducing atmosphere, which can inhibit the diffusion of oxygen and increase the viscosity.

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“…The ratio Fe 3+ /Fe 2+ increases with the iron content from S1 to S5. This is in accordance with He, 21 i.e., a higher increase of Fe 3+ than Fe 2+ as the iron level is increased.…”

Section: Methodssupporting

confidence: 88%

Different Roles of Iron Species in the Network Structure and Viscosity of Silicate Melts

Wang

Guhl

et al. 2020

Energy Fuels

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“…The local reaction atmosphere gradually varies from oxidizing to reducing along the riser. The oxidation state of iron in slags mainly reveals the variation of the local reaction atmosphere, although it is also related to various factors, such as the Fe content, temperature, and residence time. , To confirm and understand the influence of the local oxidizing atmosphere on slag formation in fluidized beds, thermodynamic calculations under oxidizing and reducing atmospheres were implemented. The calculations were based on Hc slag element composition, and the main phases where the contents exceed 5% are shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

“…The slag grew gradually until it cannot be supported by the gasification agent and then deposited on the air distributor. The variation of reaction atmosphere caused the transformation of crystal phase and solidification of liquid phase . For blended coals, magnetite was gradually generated instead of hematite.…”

Section: Resultsmentioning

confidence: 99%

“…Reaction atmosphere always varies with the geometric locations in a gasifier, which affects the ash melting behavior of high iron coal. 33 For a fluidized bed gasifier, the oxidant is introduced into the riser from the bottom and consumed in a limited zone. The local reaction atmosphere gradually varies from oxidizing to reducing along the riser.…”

Section: Resultsmentioning

confidence: 99%

“…The oxidation state of iron in slags mainly reveals the variation of the local reaction atmosphere, although it is also related to various factors, such as the Fe content, temperature, and residence time. 30,33 To confirm and understand the influence of the local oxidizing atmosphere on slag formation in fluidized beds, thermody- promotes the formation of liquid phase under a reducing atmosphere, 34 and thus, the total amount of liquid phase in a reducing atmosphere exceeds that in the oxidizing atmosphere by about 10%, within the operating temperature range of the BFB gasifier (890−920 °C).…”

Section: Resultsmentioning

confidence: 99%

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Effect of Coal Blending on Gasification Performance and Agglomeration

et al. 2020

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To localize coal utilization, a local Hongshagang bituminous coal (Hc) with low ash fusion temperatures (AFTs) was blended with the Guanghui bituminous coal (Gc). Prior to its application in an industrial fluidized bed gasifier, a series of verification tests were performed in this study for feasibility analysis. The AFTs and CO2 gasification reactivity of blended coal decrease with the increases in the additive amount of Hc. Therefore, the additive amount of Hc was determined to be 10–30% for further bubbling fluidized bed (BFB) gasification. During BFB gasification experiments, the addition of Hc lowered the gasification performance; furthermore, agglomeration and slagging occurred. The deposited slags were examined via SEM, XRF, and XRD to determine the formation mechanism. Specifically, the flux effect of Fe and Na in Hc ash promoted the slagging. The local oxidizing atmosphere in the bottom of the reactor affected the mineral transformation in slags. It changed the contents of crystal phases and led to solidification of liquid phase by comparing XRD results and Factsage calculations. At last, the formation process of slag was described based on the aforementioned experimental phenomena.

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Ash fusion characteristics of iron‐rich coal in Xinjiang under different atmospheres and the influence mechanism of adding red mud and pipeline scale

Lv,

Wang,

Zhang

et al. 2023

Asia-Pacific J Chem Eng

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To realize the high‐efficiency utilization of iron‐rich coal, it is necessary to conduct in‐depth research on the ash fusion characteristics and regulation mechanism. In this paper, the ash fusion temperature test of iron‐rich coal in Xinjiang (ZC) under different atmospheres was first carried out. Then, red mud (HJ) from Huajin Aluminum Industry and black water pipe scale (GDG) were selected as the additives. After the same ashing procedure, the two additives were mixed with iron‐rich coal ash in different proportions to realize the regulation of the chemical composition of the coal ash to improve the ash fusion characteristic. The ash fusion temperature (AFT) experiment was carried out in the automatic ash melting point analyzer, and high‐temperature ash melting slags at different temperatures were prepared. The mineral phases of coal ash and slag were characterized by XRD and compared with the Factsage simulation calculation results to reveal the influence mechanism of coal ash fusion temperature. The result shows that the fusion temperature of ZC iron‐rich coal ash is significantly different between oxidizing atmosphere and weak reducing atmosphere. Compared with the oxidizing atmosphere, the four characteristic temperatures of ZC iron‐rich coal ash are significantly lower under weak reducing conditions, and the difference is about 150°C. The addition of red mud and pipeline scale increased the fusion temperature of ZC coal ash to varying degrees. The addition of HJ ash has little effect on the deformation temperature of ZC coal ash, while the addition of different proportions of HJ ash significantly increases the flow temperature of ZC coal ash. When the addition ratio of HJ ash is 40%, the flow temperature FT of ZC coal ash increases most obviously, which is about 50°C. The addition of HJ ash and GDG ash will lead to an increase in the content of iron‐containing spinel, thereby increasing the ash flow temperature.

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Iron transformation behavior in coal ash slag in the entrained flow gasifier and the application for Yanzhou coal

Cited by 39 publications

References 29 publications

Different Roles of Iron Species in the Network Structure and Viscosity of Silicate Melts

Different Roles of Iron Species in the Network Structure and Viscosity of Silicate Melts

Effect of Coal Blending on Gasification Performance and Agglomeration

Ash fusion characteristics of iron‐rich coal in Xinjiang under different atmospheres and the influence mechanism of adding red mud and pipeline scale

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