Ash Melting Behavior of Blended Coal With Chinese Xinjiang High-Alkali Coal

This paper is aimed to clarify the ash deposition/slagging behavior of blended coal with Xinjiang High-Alkali coal (HA coal) during the combustion process in boiler. One typical Xinjiang coal (HA coal) and another low-alkali coal (LA coal) have been mixed to study the ash melting behavior as a function of coal blending ratio, through the use of AFTs test, XRD, SEM-EDX characterization of ash samples and 3MW pilot-scale test. The results indicate that, the trend of AFTs is not linearly related to the blending ratio of coal mixtures. Instead, it is highly linked with the changes on the liquidus temperature from the ternary phase diagram systems. The initial melting temperature of HA coal ash is approximately 275°C lower than that of LA coal ash due to the existence of alkali and alkaline earth metals, although it has relative higher ash fusion temperature. The mixing of LA coal is not only beneficial to reduce the amount of vaporized sodium, but it also increases the initial melting temperature of blended ash due to the physical and chemical reactions between alkali and silica particles. The higher content of Na gas was formed during HA coal combustion process due to the promoted effect of the existence of Cl in HA coal. Some low melting minerals, such as Na2SO4, Na3Fe(SO4), NaS2O7, were found as the dominate minerals in its deposit ash on heat transfer tubes in the temperature range 650∼1000°C when combustion HA coal. When blended with other LA coal, the amount of deposit ash was decreased and the shape of it became looser due to some high melting minerals were found in its deposit ash, such as quartz and mullite etc. The optimum blending ratio of LA coal is 20% for its safe operation for HA coal.

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The Effect of Calcium-Bearing Mineral on Ash Melting Behavior During Zhundong Coal Combustion

10.1115/power-icope2017-3221 ◽

2017 ◽

Author(s):

Ma Haidong ◽

Wang Yungang ◽

Zhao Qinxin

Keyword(s):

Calcium Oxide ◽

Coal Combustion ◽

Coal Ash ◽

Melting Behavior ◽

Sintering Behavior ◽

Efficient Operation ◽

Transition Mechanism ◽

Ash Melting ◽

Zhundong Coal ◽

Ash Melting Behavior

Two typical pulverized Zhundong coal with different calcium oxide contents in ash were selected to use in this work. The liquid nitrogen was used to cool ash rapidly at different temperatures, in order to avoid changes in mineral condition. The ash melting behavior and mineral transition mechanism, especially calcium-bearing minerals was studied by ash melting point test platform, XRD, XRF, SEM and EDS. The results showed that the different states of calcium are the dominant reasons for different sintering behaviors of coal ash. The calcium-bearing minerals in ash, such as calcium oxide (CaO), calcium silicate (CaSiO3), gehlenite (2CaO·Al2O3·SiO2), and anorthite (CaO·Al2O3·2SiO2), etc., are the most important factors influencing the initial sintering behavior of coal ash in the temperature range from 1373K to 1473K under oxidizing atmosphere during coal combustion. That is the reason why ash starts to melt at relatively high temperature during ash melting behavior in laboratory, but has severe slagging and contamination characteristic at low temperature during coal combustion in boilers. The research achievments have important guiding significance for the design of partially or completely burning Zhundong coal boiler as well as its long-term safe and efficient operation. (CSPE)

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Prediction of Ash Melting Behavior from Coal Ash Composition

Analytical Methods for Coal and Coal Products ◽

10.1016/b978-0-12-399903-0.50022-2 ◽

1979 ◽

pp. 481-487

Author(s):

Karl S. Vorres

Keyword(s):

Coal Ash ◽

Melting Behavior ◽

Ash Composition ◽

Ash Melting ◽

Ash Melting Behavior

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Experimental Study on Ash Melting Behavior of Xinjiang High-Alkali Coal Blended with Low-Alkali Coal During Coal Combustion

Clean Coal Technology and Sustainable Development ◽

10.1007/978-981-10-2023-0_7 ◽

2016 ◽

pp. 53-58 ◽

Cited By ~ 1

Author(s):

Xiang Zhang ◽

Xiaojiang Wu ◽

Xueyuan Xu ◽

Jianwen Zhang ◽

Kai Yan ◽

...

Keyword(s):

Experimental Study ◽

Coal Combustion ◽

Melting Behavior ◽

Ash Melting ◽

Ash Melting Behavior ◽

High Alkali

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Experimental Investigation of Ash Deposit Behavior during Co-Combustion of Bituminous Coal with Wood Pellets and Empty Fruit Bunches

Energies ◽

10.3390/en12112087 ◽

2019 ◽

Vol 12 (11) ◽

pp. 2087 ◽

Cited By ~ 5

Author(s):

Tae-Yong Jeong ◽

Lkhagvadorj Sh ◽

Jong-Ho Kim ◽

Byoung-Hwa Lee ◽

Chung-Hwan Jeon

Keyword(s):

Melting Temperature ◽

Power Plants ◽

Bituminous Coal ◽

Coal Ash ◽

Milling Process ◽

Drop Tube ◽

Ash Deposition ◽

Wood Pellets ◽

Empty Fruit Bunches ◽

Ash Melting

In Korea, oil-palm empty fruit bunches (EFBs), which are byproducts of the crude palm-oil milling process, are among the most promising potential energy sources for power plants. However, the slagging and fouling characteristics of EFBs during combustion have not yet been fully studied. Accordingly, in this study, we investigated the fundamental ash behavior of EFBs in comparison to that of wood pellets (WPs) using a thermomechanical analyzer (TMA) and a drop-tube furnace (DTF). Ash melting and the deposition of ash particles were investigated with traditional prediction indices at several biomass blending ratios. The results demonstrated that, as the ratio of WPs to EFBs increases, the melting temperature decreases and the slagging propensity increases because of the increased biomass alkali content. Moreover, the penetration derived using the TMA shows a higher melting peak at which rapid melting occurs, and the melting temperature distribution is decreased with increased biomass blending. Conversely, the DTF results show different phenomena for ash deposition under the same blending conditions. Blend ratios approaching 10% WP and 15% EFB result in gradual decreases in ash deposition tendencies because of the lower ash contents of the co-combusted mass compared to that of the single coal ash. Further biomass addition increases ash deposition, which is attributable to ash agglomeration from the biomass. Thus, this study demonstrates that blending ratios of 10% WP and 15% EFB provide optimal conditions for co-combustion with the selected bituminous coal. In addition, it is shown that the slagging propensity of EFB is higher than that of WP owing to its ash content and simultaneous agglomeration.

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Characterization of Vinasse for Thermochemical Conversion—Fuel Fractionation, Release of Inorganics, and Ash-Melting Behavior

Energy & Fuels ◽

10.1021/acs.energyfuels.8b04177 ◽

2019 ◽

Vol 33 (7) ◽

pp. 5840-5848 ◽

Cited By ~ 2

Author(s):

Meheretu Jaleta Dirbeba ◽

Anders Brink ◽

Maria Zevenhoven ◽

Nikolai DeMartini ◽

Daniel Lindberg ◽

...

Keyword(s):

Melting Behavior ◽

Thermochemical Conversion ◽

Ash Melting ◽

Ash Melting Behavior

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Effect of High-Efficiency Flux on the Melting Characteristics of Coal Ash

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.295-298.3094 ◽

2013 ◽

Vol 295-298 ◽

pp. 3094-3097 ◽

Cited By ~ 1

Author(s):

Han Xu Li ◽

Zi Li Zhang ◽

Yong Xin Tang

Keyword(s):

Melting Temperature ◽

Coal Gasification ◽

High Efficiency ◽

Coal Ash ◽

Fusion Temperature ◽

Gasification Process ◽

Ash Fusion Temperature ◽

Melting Characteristics ◽

Temperature Detector ◽

Ash Melting

High-efficiency flux was developed to lower the ash fusion temperature of coal LQ and reduce the addition content in coal gasification process. The effect of high-efficiency flux on the coal ash melting temperature and mineral transformation were studied by ash fusion temperature detector and XRD (X-ray diffractometer) respectively in reducing atmosphere. Compared with limestone flux, the high-efficiency flux can decrease the coal ash melting temperature effectively with half addition content. The ash flow temperature (FT) of coal LQ can be lowered to less than 1350°C with the addition of 3% high-efficiency flux ,while limestone flux need to add more than 8% to reach to this temperature. With the high-efficiency flux added, cordierite, anorthite and Mg-Fe-Al oxide were formed at high temperature, which is the main reason to sharply decrease the ash fusion temperature.

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