Slagging and Fouling Characteristics of Zhundong High-Sodium Low-Rank Coal during Circulating Fluidized Bed Utilization

Qi, Xiaobin; Song, Guoliang; Song, Weijian; Yang, Shu; Zhao, Yang; Lyu, Qinggang

doi:10.1021/acs.energyfuels.7b02053

Cited by 27 publications

(17 citation statements)

References 49 publications

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“…However, the process was still a major challenge because of the diversity of fuels. Song et al 17,18 carried out extensive work on the utilization of ZD coal in a CFB. The results showed that reaction temperature, reaction atmosphere and coal properties had considerable influences on the ash deposition characteristics.…”

Section: Introductionmentioning

confidence: 99%

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Ash deposition behavior of a high-alkali coal in circulating fluidized bed combustion at different bed temperatures and the effect of kaolin

Liu

Cheng

et al. 2018

RSC Adv.

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High alkali and alkali earth metals (AAEMs) content in coal causes severe slagging and fouling during combustion in a boiler. In this study, the ash deposition behavior of a high-alkali coal at different bed temperatures and the effect of kaolin were investigated in a 30 kW circulating fluidized bed (CFB) test system using an ash slagging probe and deposition probe. The results show that the ash deposition tendency increases with the bed temperature. The condensation of Na 2 SO 4 is an important inducement for slag formation in the furnace. The melting or partial melting of slags is attributed to Na-Fe-Ca eutectics. At 920 C, Na 2 SO 4 will react with CaSO 4 to form the low-melting compound of Na 2 SO 4 -CaSO 4 . The deposited ash on the convection-heating surface consists of granular particles. On the windward side, the layered-structure ash deposits, i.e. the inner and outer layers, are formed at the bed temperature of 920 C but are absent at lower temperatures (820 C and 870 C). The formation of the inner layer consists of fine particles (<2 mm) and is closely related to Na 2 SO 4 . The size of the deposited ash in the outer layer is larger than 10 mm, while that on the leeward side is less than 10 mm. By adding kaolin in the coal, the slags are replaced by loose particles due to the absorption reactions between kaolin and alkali metals. The ash deposition tendency is improved and the optimal result is achieved when kaolin is added at an addition ratio of 3%.

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Section: Introductionmentioning

confidence: 99%

“…The degree of slagging in the furnace increased as a function of the reaction temperature during gasification. 17 Under combustion conditions, the fouling on heating surfaces at medium temperatures (607–735 °C) was the main ash-related problem. 18 However, the influence of the combustion temperature on fouling is not clear.…”

Section: Introductionmentioning

confidence: 99%

Ash deposition behavior of a high-alkali coal in circulating fluidized bed combustion at different bed temperatures and the effect of kaolin

Liu

Cheng

et al. 2018

RSC Adv.

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“…Figure 6 b shows the weight of slags deposited on the slagging probe during the CFBG of SHc. 36 The weight of slags deposited directly reflects the slagging degree. According to the weight of slags, it is inferred that the CFBG process of SHc is free from slagging at 900 °C because the weight of slags is almost zero.…”

Section: Resultsmentioning

confidence: 99%

Influence of Ashing Temperature on Predicting Slagging Characteristics of Xinjiang High-Sodium Low-Rank Coal and Strategy of Using Mineral Additives as Potential Slagging Preventatives

Song

2021

ACS Omega

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It is crucial to accurately evaluate the slagging characteristics of coal before industrial application. However, when evaluating the Xinjiang high-sodium low-rank coal (XJc) according to the properties of the ash prepared at 815 °C, the ashing temperature of the coal sample specified by Chinese standards, forecasting failures are frequent. To figure out the internal reason, the influence of ashing temperature on predicting slagging characteristics of XJc was investigated via an ashing test and thermodynamic equilibrium calculation. Experimental results show that when XJc is ashed at 815 °C, the ash yield apparently reduces compared to the case when ashed at 500 °C since numerous volatile components are released. The release of these components contributes to an obvious inhibition in the formation of the liquid phase in the residual ash, especially at temperatures below 1200 °C. Hence, reducing the ashing temperature is conducive to the acquirement of more real ash compositions of XJc and thereby to the accurate prediction of the slagging behaviors. By a comparison with reported experimental results, it is found that the liquid ratio–temperature curve calculated from the ash compositions of the ash prepared at 500 °C basically reflects the actual slagging tendency of XJc. According to the evolution of minerals with temperature, two slagging mechanisms, self-fusion of sodium-bearing salts and low-temperature eutectics, are confirmed. In addition, effects of antislagging measures of adding refractory oxides greatly differ among coal types due to the diversity in ash compositions.

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“…The existence of the slag hinders the heat transfer, which reduces the boiler thermal efficiency. 12,13 In addition, there are some corrosive components in the ash slag that cause corrosion and damage to the boiler, which directly threaten the safe operation of the power plant boiler. 14 Given the above problems, the combustion technology of liquid slag removal boiler possesses high combustion intensity, high slag removal rate, and low dust content in flue gas, which is particularly suitable for slagging coal.…”

Section: Introductionmentioning

confidence: 99%

“…However, Zhundong coal is prone to slagging due to its high content of alkali metals. The existence of the slag hinders the heat transfer, which reduces the boiler thermal efficiency 12,13 . In addition, there are some corrosive components in the ash slag that cause corrosion and damage to the boiler, which directly threaten the safe operation of the power plant boiler 14 .…”

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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Slagging and Fouling Characteristics of Zhundong High-Sodium Low-Rank Coal during Circulating Fluidized Bed Utilization

Cited by 27 publications

References 49 publications

Ash deposition behavior of a high-alkali coal in circulating fluidized bed combustion at different bed temperatures and the effect of kaolin

Ash deposition behavior of a high-alkali coal in circulating fluidized bed combustion at different bed temperatures and the effect of kaolin

Influence of Ashing Temperature on Predicting Slagging Characteristics of Xinjiang High-Sodium Low-Rank Coal and Strategy of Using Mineral Additives as Potential Slagging Preventatives

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

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