Xinjiang lignite ash slagging and flow under the weak reducing environment at 1300 °C – Release of sodium out of slag and its modelling from the mass transfer perspective

Ji, Hengsong; Wu, Xiaojiang; Dai, Baiqian

doi:10.1016/j.fuproc.2017.10.016

Cited by 41 publications

(19 citation statements)

References 20 publications

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“…The obtained ash samples were put back to the muffle furnace again for another 20 min. Repeat the reburning process until the mass change was less than 0.001 g. 29 For the corrosion test, the alumina ceramic was selected as the refractory material, which is affordable and widely used in the refractory of gasifiers. 30,31 The sample holder is a round shape plate in the size of 30 mm diameter with a thickness of 2.5 mm, which was made from high-purity Al 2 O 3 with an open porosity of 5−6.5% and a bulk density of 3.6 g/cm 3 .…”

Section: Experimental Methodologymentioning

confidence: 99%

“…The atmosphere in the furnace is a reducing atmosphere of 60 vol % CO balanced by N 2 , which is consistent with our previous investigation. 29,32 The gas flow was adjusted by the gas control system. In the corrosion test, the ash samples were heated to 800 °C by a fast heating rate of 10 K/min since there is no significant mineral transformation in this temperature range.…”

Section: Experimental Methodologymentioning

confidence: 99%

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Bio-Slag High-Temperature Corrosion on an Alumina Refractory under the Reducing Environment

Yan

et al. 2021

Energy Fuels

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The alkali and alkaline earth metals in the biomass are one of the major challenges that restrict the biomass/low-rankcoal entrained-flow gasification in the way of ash slagging and corrosion. To clarify the corrosive behavior from bio-slag on the refractory material of the gasifiers, this study investigates the blending of biomass with coal for high-temperature corrosion on an alumina refractory in a vertical furnace under the reducing environment. The ash samples from a typical wheat straw (WS) and a Shenhua bituminous coal (SH), as well as their blends in three different mass ratios at 10 wt % WS, 30 wt % WS, and 50 wt % WS, were selected for high-temperature corrosion tests at 1350 °C for 2 h holding time. The obtained slag, especially the cross section, was examined using optical microscopy, scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), and Raman spectral analysis. Additionally, the thermodynamic calculation was conducted using Factsage. The results show that the addition of WS into SH lowers the ash fusion temperature. The WS30 blends have the lowest ash fusion temperature with a fully molten phase at 1130 °C. The addition of WS promotes the slag fluidity, while adding 30% of WS into SH results in the largest spreading area. Interestingly, the slag with a higher fluidity is more corrosive, indicated by a larger filtrated area and depth in the cross section. Elemental mapping results show that the ash-forming elements are evenly distributed in the slag for fully melted samples. However, the Mg species precipitated near the slag-refractory interface and react with alumina to form a spinel phase that prevents further penetration.

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Section: Experimental Methodologymentioning

confidence: 99%

Section: Experimental Methodologymentioning

confidence: 99%

Bio-Slag High-Temperature Corrosion on an Alumina Refractory under the Reducing Environment

Yan

et al. 2021

Energy Fuels

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“…To minimize ash deposition during the combustion, substantial efforts are made to study the ash deposition mechanisms. It is confirmed that clay compounds, such as kaolin, quartz, and fly ash, even the biomass materials, have a positive effect on ash deposition 7–12 . Their works, listed in Table 1, mainly focus on the effect of additives on Na capture and AFTs.…”

Section: Introductionmentioning

confidence: 97%

“…Many scholars believe that Na element is the main cause for ash deposition during lignite combustion, such as Australia Victory and China Zhundong 7–12 . During lignite combustion, the Na are likely to convert into gas‐phase species and result serious ash deposition.…”

Section: Introductionmentioning

confidence: 99%

The effect on ash deposition by blending high‐calcium Zhundong coal with vermiculite: Focusing on minerals transformations

Yang

Jin

Liu

et al. 2020

Asia-Pacific J Chem Eng

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To solve the ash deposition problem caused by burning high‐calcium Zhundong coal (ZDC), the addition of vermiculite is a promising solution. However, complete mechanisms of vermiculite addition reducing ash deposition are still unknown. In this paper, the effect of vermiculite on sodium emission, ash fusion characteristics, and mineral transformation is investigated. The results show that although vermiculite, with limited Na capture capacity, lowers the ash fusion temperatures (AFTs), it can greatly reduce ash deposition. In the combustion of ZDC, calcium‐bearing minerals will react with clay minerals and then convert to molten glassy phase. Those molten minerals will take high melting point minerals, Ca2Al2SiO7 and CaMgSi2O6, as bone, showing slagging phenomenon with high AFTs. When vermiculite is introduced, the main reaction products are Ca2MgSi2O7 and Mg2SiO4 and that reduces the extent of molten minerals formation. The main ash product transforming from Ca2Al2SiO7 to Ca2MgSi2O7 leads to the decrease of AFTs. The initial ash deposition with Ca2Al2SiO7 still happens; however, vermiculite addition makes it hard for ash to grow on the existing ash deposit. The results of FactSage software agree with the experimental ones, and the proportion of slag decreases by 36% with vermiculite at 1250°C.

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“…Du and Xu et al 17,18 observed the morphological changes of the ash samples at high temperatures through the heating stage microscope; then, the flow characteristics of samples were evaluated by their area shrinkage. Ji and Wu et al 23,24 established a visual measurement method for slag fluidity. The slag samples were placed on a corundum plate with an inclination of 25 , and the flow characteristics of the slag samples were evaluated by measuring the distance of melt flow.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on flow properties of coal ash slag based on the image measurement method

Luo

Zhou

Wang

et al. 2021

Asia-Pacific J Chem Eng

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This paper aims to reveal the effect of adding biomass ash on the flow characteristics of Zhundong (ZD) coal ash. A new visual image measurement method for the flowability of coal ash was established. Furthermore, scanning electron microscopy (SEM) and x-ray diffraction (XRD) were applied to analyze the influence of surface morphology and mineral component on the fusion fluidity of the samples. The results show that the flow properties of ZD ash are improved to varying degrees after adding maize straw (MS) ash. As the blending ratio increases, the improvement of flow velocity is higher. The critical flow temperature (T C ) of the samples was calculated. The T C of ZD ash was 1249 C, which decreased with the addition of MS ash. The characterization

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Xinjiang lignite ash slagging and flow under the weak reducing environment at 1300 °C – Release of sodium out of slag and its modelling from the mass transfer perspective

Cited by 41 publications

References 20 publications

Bio-Slag High-Temperature Corrosion on an Alumina Refractory under the Reducing Environment

Bio-Slag High-Temperature Corrosion on an Alumina Refractory under the Reducing Environment

The effect on ash deposition by blending high‐calcium Zhundong coal with vermiculite: Focusing on minerals transformations

Experimental study on flow properties of coal ash slag based on the image measurement method

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