A mechanistic study of the formation of slags from iron-rich coals

Brink, H.M. ten; Eenkhoorn, S.; Hamburg, G.

doi:10.1016/0016-2361(96)00048-8

Cited by 32 publications

(19 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Yang et al 39 also found that SiO 2 could react with CaO to generate low MP anorthite/gehlenite‐based eutectic, leading to severe slagging. It was worth noting that the S content was extremely low in #1 slag, implying that S was hard to deposit in the FGT > 1000°C zone, which was also confirmed by other researches 40 …”

Section: Resultssupporting

confidence: 81%

“…It was worth noting that the S content was extremely low in #1 slag, implying that S was hard to F I G U R E 1 1 SEM-EDX test of ash of two panels (a: SEM, b: EDX) deposit in the FGT > 1000 C zone, which was also confirmed by other researches. 40 The ash deposit on #2 consists of larger unmolten and sintered particles with FGT ranging from 995 C to 1008 C in section B. It is confirmed that #1 has higher deposition strength than #2 because it contains more liquid slag.…”

Section: Morphology and Mineral Composition Of Deposited Ashmentioning

confidence: 57%

See 1 more Smart Citation

Ash deposition and heat transfer characteristics on the convective heating surface of calcium‐rich Zhundong coal combustion in a 0.4‐MW_th facility

Jin

Yang

et al. 2022

Asia-Pacific J Chem Eng

View full text Add to dashboard Cite

Thermal power plants in Zhundong area of Xinjiang equip Π-typed boiler widely in recent years. With the increasing ratio of Zhundong coal in blended fuels, the slagging is strengthened. And the boiler shutdown was caused by ash deposition on the convective heating surface frequently. In order to study the mechanism of this problem, a 0.4-MW th pilot-scale facility was built and expected to study ash deposition and heat transfer characteristics on the convective heating surface of 100% burning calcium-rich Zhundong coal.Thermodynamic model calculation was implemented on the heat transfer characteristics of two groups of tube panels, on which ash samples were collected after experiments. Then, simulation calculation was applied by software for verification. The ash samples were characterized by X-ray diffraction spectroscopy (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray detector (EDX). FactSage 7.3 thermochemical software package and a high-temperature viscometer were also used to figure out the viscosity-temperature characteristics. Results showed that a "step change" of heat transfer characteristics occurred when the flue gas temperature of inlet tube panel #2 approached to 1000 C. After the "step change," the heat transfer characteristics became stable. The ash deposition mainly consisted of siliconcalcium compounds of tube panel #1, while in contrast, that of tube panel #2 consisted of gehlenite, CaSO 4 , and Na 2 SO 4 . The ratio of liquid phase in raw coal ash samples increased sharply when the flue gas temperature exceeded 1030 C. With the increase of surface temperature of fouling tube panel, the CaSO 4 would be decomposed to release CaO, which reacted with gehlenite or other compounds to form low temperature eutectics. The fouling of ash would transfer to slagging and lead to the deterioration of ash deposition, which induced the formation of "step change" during the experiment.

show abstract

Section: Resultssupporting

confidence: 81%

Section: Morphology and Mineral Composition Of Deposited Ashmentioning

confidence: 57%

Ash deposition and heat transfer characteristics on the convective heating surface of calcium‐rich Zhundong coal combustion in a 0.4‐MW_th facility

Jin

Yang

et al. 2022

Asia-Pacific J Chem Eng

View full text Add to dashboard Cite

show abstract

“…Combustion conditions such as temperature, oxygen concentration, and residence time have a significant influence on the ash formation process. Recent interest in low NO x combustion and coal gasification has led to research into ash formation processes in reducing conditions, − which are known to lower melting temperatures and influence mineral transformations. − ,, Though reducing conditions may not have significant influence on included minerals during char combustion, as the char produces a locally reducing environment regardless of combustion stoichiometry, there may be major influences following char combustion. Reducing conditions may also have a notable impact on excluded minerals, particularly iron-based minerals.…”

Section: Introductionmentioning

confidence: 99%

Ash Formation Mechanisms during pf Combustion in Reducing Conditions

et al. 1999

View full text Add to dashboard Cite

A range of pulverized coals were combusted in a laboratory drop-tube furnace at temperatures of 1573, 1723, and 1873 K under oxidizing and reducing conditions to determine the effect of combustion stoichiometry on ash formation mechanisms. As iron mineral transformations were expected to be most affected by combustion stoichiometry, two of the test coals chosen were of high pyrite (FeS2) content and two of high siderite (FeCO3) content. It was found that the ash formation mechanisms of excluded quartz, koalinite, and calcite were not affected by oxidizing or reducing combustion conditions. Excluded pyrite was found to decompose to pyrrhotite, which oxidized to produce an FeO−FeS melt phase which was stable under reducing conditions. Under oxidizing conditions oxidation continued, producing magnetite and hematite. Excluded siderite was found to decompose to wustite, which was stable under reducing conditions, but oxidized to produce magnetite under oxidizing conditions. Included pyrite and siderite were determined to behave as for excluded pyrite and siderite if there was no contact with alumino-silicates. Included pyrite that contacted alumino-silicate minerals was observed to form two-phase FeS/Fe-glass ash particles, with incorporation of iron into the glass proceeding as the FeS phase was oxidized. Included siderite that contacted alumino-silicate minerals was determined to directly form iron alumino-silicate glass ash particles. Iron alumino-silicate glass ash was determined to form with iron in the Fe2+ state, much of which subsequently transformed to the Fe3+ state in oxidizing conditions, but remained primarily as in the Fe2+ state under reducing conditions.

show abstract

“…However, as the primary deposit increases in thickness, its surface temperature will rise, and the deposits will become semi-molten. This sticky surface will then be able to capture and retain any higher melting point particles such as silicates [5][6][7]. This may explain why, at a certain thickness and a sufficiently high gas temperature, the deposits grow rapidly [8].…”

Section: Introductionmentioning

confidence: 99%

Efficient Low-Driving-Voltage Blue Phosphorescent Homojunction Organic Light-Emitting Devices

Cai¹,

Chiba³

et al. 2011

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

This paper is concerned with the development of a system to detect and monitor slag growth in the near burner region in a pulverized-fuel (pf) fired combustion rig. These slag deposits are commonly known as 'eyebrows' and can markedly affect the stability of the burner. The study thus involved a series of experiments with two different coals over a range of burner conditions using a 150 kW pf burner fitted with simulated eyebrows. These simulated eyebrows consisted of annular refractory inserts mounted immediately in front of the original burner quarl. Data obtained by monitoring the infra-red radiation and sound emitted by the flame were processed to yield time and frequency-domain features, which were then used to train and test a hybrid neural network. This hybrid 'intelligent' system was based on self organizing map and radial-basis-function neural networks. This system was able to classify different sized eyebrows with a success rate of at least 99.5%. Consequently, it is possible not only to detect the presence of an eyebrow by monitoring the flame, but also the network can provide an estimate of the size of the deposit, over a reasonably large range of conditions.

show abstract

A mechanistic study of the formation of slags from iron-rich coals

Cited by 32 publications

References 1 publication

Ash deposition and heat transfer characteristics on the convective heating surface of calcium‐rich Zhundong coal combustion in a 0.4‐MW_th facility

Ash deposition and heat transfer characteristics on the convective heating surface of calcium‐rich Zhundong coal combustion in a 0.4‐MW_th facility

Ash Formation Mechanisms during pf Combustion in Reducing Conditions

Efficient Low-Driving-Voltage Blue Phosphorescent Homojunction Organic Light-Emitting Devices

Contact Info

Product

Resources

About

A mechanistic study of the formation of slags from iron-rich coals

Cited by 32 publications

References 1 publication

Ash deposition and heat transfer characteristics on the convective heating surface of calcium‐rich Zhundong coal combustion in a 0.4‐MWth facility

Ash deposition and heat transfer characteristics on the convective heating surface of calcium‐rich Zhundong coal combustion in a 0.4‐MWth facility

Ash Formation Mechanisms during pf Combustion in Reducing Conditions

Efficient Low-Driving-Voltage Blue Phosphorescent Homojunction Organic Light-Emitting Devices

Contact Info

Product

Resources

About

Ash deposition and heat transfer characteristics on the convective heating surface of calcium‐rich Zhundong coal combustion in a 0.4‐MW_th facility

Ash deposition and heat transfer characteristics on the convective heating surface of calcium‐rich Zhundong coal combustion in a 0.4‐MW_th facility