Spectroscopic research on infrared emittance of coal ash deposits

Saljnikov, Aleksandar; Vučićević, Biljana; Komatina, Mirko; Gojak, Milan; Goričanec, Darko; Stevanović, Zoran

doi:10.1016/j.expthermflusci.2009.07.002

Cited by 12 publications

(13 citation statements)

References 6 publications

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“…The model given in Sec. The results show that the ash deposit spectral emissivities increase with increasing temperature which agrees with previous results [8,9,11,12]. However, due to the lack of temperature-2.0 Fig.…”

Section: Effects Of Temperaturesupporting

confidence: 91%

“…2 for two ash deposit samples. The results are not compared with other experimental data [8][9][10][11][12] due to the lack of sufficient information conceming the ash deposits. The results are not compared with other experimental data [8][9][10][11][12] due to the lack of sufficient information conceming the ash deposits.…”

Section: Effects Of Mierostructurementioning

confidence: 99%

“…Since the ash deposit microstructures change with temperature and the microstructure significantly affects the spectral emissivity [2,8,9], the effects of temperature on the ash deposit spectral emissivities are actually attributed to the accordingly changed ash deposit microstructure. The model given in Sec.…”

Section: Effects Of Temperaturementioning

confidence: 99%

“…Saljnikov et al [8,9] measured temperature dependent total and spectral emissivities for four kinds of ash deposits for temperatures from 560 to 1460 K. Moore et al [10] measured in situ spectral emissivities of ash deposits formed by burning bituminous and sub-bituminous coals. Saljnikov et al [8,9] measured temperature dependent total and spectral emissivities for four kinds of ash deposits for temperatures from 560 to 1460 K. Moore et al [10] measured in situ spectral emissivities of ash deposits formed by burning bituminous and sub-bituminous coals.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Predictions of Spectral Emissivity for Coal Ash Deposits

Liu

Duan

Yang

et al. 2014

Journal of Heat Transfer

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Coal ash inevitably forms deposits as combustion residue on the walls and heat transfer surfaces of coal-fired boilers. Ash deposits decrease the boiler efficiency, reduce the generating capacity, and cause unscheduled outages. The radiative heat transfer is the major heat transfer mechanism in utility boilers: thus, the ash deposit emissivity is critical to boiler efficiency and safety. This paper presents a radiative transfer model to predict the spectral emissivities of coal ash deposits. The model includes the effects of the microstructure, chemical composition, and temperature. Typical ash deposit microstructures are generated using diffusion-limited aggregation (DLA). The radiative properties are then calculated using the generalized multiparticle Mie-solution (GMM). The combined GMM and DLA model predicts spectral emissivity better than the original Mie theory and Tien's dependent scattering theory with the average relative difference between predicted results and experimental data decreasing from 17.8% to 9.1% for sample 1 and from 18.6% to 4.2% for sample 2. Maxwell-Garnett (MG) effective medium theory is used to calculate the ash deposit optical constants based on the chemical compositions to include the effect of chemical composition. Increasing temperatures increase the particle diameters and particle volume fractions and, thus, the spectral emissivities. The spectral emissivity ultimately remains constant and less than one. The homogeneous slab model gives the upper limit of the ash deposit spectral emissivity.

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Section: Effects Of Temperaturesupporting

confidence: 91%

Section: Effects Of Mierostructurementioning

confidence: 99%

Section: Effects Of Temperaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Theoretical Predictions of Spectral Emissivity for Coal Ash Deposits

Liu

Duan

Yang

et al. 2014

Journal of Heat Transfer

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“…Most numerical studies for the prediction of ash deposition have reported on only a single coal, not blends. For only the ash characteristic, Saljnikov et al [12] conducted an investigation of total and normal spectral emittance of lignite ash deposits formed on heat exchanger surfaces in a boiler furnace.…”

Section: Introductionmentioning

confidence: 99%

The effect of blending of bituminous and sub-bituminous coals on ash fusibility and deposition formation

et al. 2016

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Coal is an important energy source whose consumption increases continuously. One of the many ways to use coal is coal blending, which is a very effective technique in power stations. However, coal blending generates unsuspected problems, one of which is ash deposition that causes slagging and fouling. In fact, most blends accelerate and generate heavier ash depositions than their parent coals.This work investigates the characteristics of ash behavior including fusibility and deposition when blending both bituminous and subbituminous coals in a pulverized coal combustion. Two coals used in Japan were used for this study: bituminous (Bit-A) and subbituminous coal (Sub-A). In order to investigate, the blending ratio was changed. A Thermomechanical analysis (TMA) and a Drop tube furnace (DTF) were used for ash fusibility and deposit, respectively. Ash components were determined using X-ray fluorescence at the coal research center of Idemitsu Kosan Co., Ltd., in Japan. These tests revealed that as the blending ratio of Sub-A increased, fusibility in the TMA and the melting propensity increased. Capture efficiency and energy-based growth increased with the blending ratio, and were highest at 80%. Finally, a new approach based on the relation between ash fusibility and deposit derived for predicting adhesion tendency on blended coals was created by deriving the relation between the fusibility and deposit results that affected slag formation.

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Effect of rice husk and petroleum coke blending on combustion characteristics of high ash Indian coals

Kumar

Nandi

2021

Biomass Conv. Bioref.

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This work reports the combustion characteristics of two high ash Indian coal, petroleum coke, rice husk, and their blends to assess the effect of rice husk and petroleum coke blending on combustion characteristics of high ash Indian coals. Based on the combustion data obtained from the thermogravimetric analysis, various burning profile parameters such as ignition temperature, burnout temperature, activation energy, and combustion efficiency were analyzed to identify the impacts of petroleum coke and rice husk blending on coal combustion. Results show that petroleum coke having 8602 kcal/kg gross calorific value but inferior combustion properties compared to coal and rice husk. For coal A blends with 10% petroleum coke, with the increase in rice husk content in blends from 10 to 40%, ignition temperature decreased from 409 to 270 O C, burnout temperature dropped from 506 to 502 O C, inferring significant improvements in combustion properties compared to coal and petroleum coke. For coal B blends with 10% petroleum coke, at 300 O C with the increase in rice husk in blends from 10 to 40%, combustion efficiency increased from 4.84 to 19.21%. For 20% petroleum coke of coal B blends, with the increase in rice husk in blends from 10 to 30%, activation energy decreased from 82.54 to 57.69 kJ/mol. Synergistic analysis infers that blending of higher biomass promotes synergistic due to catalytic effect. Analysis of changes in enthalpy, Gibbs free energy and entropy implied that individual combustion of both coal and petroleum coke is difficult compared to rice husk, whereas blending of rice husk makes the combustion process significantly favorable.

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Spectroscopic research on infrared emittance of coal ash deposits

Cited by 12 publications

References 6 publications

Theoretical Predictions of Spectral Emissivity for Coal Ash Deposits

Theoretical Predictions of Spectral Emissivity for Coal Ash Deposits

The effect of blending of bituminous and sub-bituminous coals on ash fusibility and deposition formation

Effect of rice husk and petroleum coke blending on combustion characteristics of high ash Indian coals

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