The melting potential of various ash components generated from coal combustion: Indicated by the circularity of individual particles using CCSEM technology

Wen, Chang; Xu, Minghou; Zhou, Kui; Yu, Dunxi; Zhan, Zhonghua; Xin, Mo

doi:10.1016/j.fuproc.2015.01.012

Cited by 29 publications

(17 citation statements)

References 39 publications

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“…The details of CCSEM analyses were introduced in our previous research. 25 It should be noted that unknown mineral is the ash that has complex elements and could not match any of the prescribed categories. To assess ash fusibility, the slag liquid phases likely formed at high temperatures were estimated by thermodynamic equilibrium calculation that is based on the minimization of Gibbs free energy.…”

Section: Methodsmentioning

confidence: 99%

Ash Formation and Deposition in Oxy-fuel Combustion of Rice Husk, Coal, and Their Blend with 70% Inlet O₂

Wang

Han

et al. 2019

Energy Fuels

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Managing the risk of ash deposition is still a priority for oxy-fuel combustion of biomass−coal blends. This is especially a concern when high inlet O 2 concentrations are adopted to reduce the amount of recycled flue gas, which results in higher combustion temperatures and lower gas flow rates. Such changes are expected to affect ash formation and deposition but have little been investigated. Rice husk has been reported to induce no ash-related problems under fluidized bed combustion conditions. However, it is unclear regarding ash formation and deposition behavior during oxy-fuel combustion of a rice husk− coal blend with high O 2 concentrations. Particular interests of this work include the effects of rice husk co-firing and hightemperature oxy-fuel combustion on ash transformation and its correlation with ash deposition behavior. Chinese rice husk (RH), bituminous coal (SF), and their blend (the share of rice husk is 16 wt %, SF/RH) were tested in this work. Experiments were carried out on a 100 kW pilot scale combustor under oxy-fuel (O 2 /CO 2 = 70/30 vol %, OXY70) and air combustion conditions. Both the bulk ash and fouling deposits were collected and characterized by techniques, such as computer-controlled scanning electron microscopy and X-ray fluorescence. Results show that co-firing rice husk increases ash particle size distributions (PSDs) and results in higher quartz and complex aluminosilicates in the ash. Coarse ash particles generated from rice husk combustion tend to dilute the deposits and cause its shedding. Consequently, the development of SF/RH deposit weight gain is suppressed. In comparison to air combustion, OXY70 combustion promotes mineral interaction and leads to coarser PSDs. For SF and RH, OXY70 combustion increases ash deposition propensity because of the higher ash impaction efficiency and average capture efficiency. For SF/RH, OXY70 combustion increases ash deposition propensity. The effect of OXY70 combustion on ash deposition propensity is mainly related to the behavior of coarse ash particles from rice husk and the changing of the gas flow rate in the furnace.

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Section: Methodsmentioning

confidence: 99%

Ash Formation and Deposition in Oxy-fuel Combustion of Rice Husk, Coal, and Their Blend with 70% Inlet O₂

Wang

Han

et al. 2019

Energy Fuels

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“…In order to avoid acid gas condensation and particle coagulation during sampling, the entire sampling system was externally heated to 120 °C [39]. Moreover, the Zhundong coal sample was subjected to a CCSEM analysis (Computer-Controlled Scanning Electron Microscopy, GENESIS XM, EDAX Inc., Mahwah, NJ, USA), according to the detailed procedures presented in our prior studies [34,35]. Though it cannot be used to analyze organically bound elements, CCSEM technology is beneficial for determining the types and contents of inorganic minerals and the mass fraction of major elements distributed in those minerals.…”

Section: Experimental Setup and Sample Analysismentioning

confidence: 99%

Emission Behaviors of Inorganic Ultrafine Particles during Zhundong Coal Oxy-Fuel Combustion with Characterized Oxygen Input Fractions Comparable to Air Combustion

et al. 2018

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Zhundong low-rank coal is very likely to be utilized extensively in oxy-fired boilers in the near future. Its PM10 (particulate matter with an aerodynamic diameter of ≤10 μm) emission behaviors during oxy-fuel combustion need to be carefully studied before its large-scale use. The present study examines the emission behaviors of inorganic ultrafine particles (PM0.5, with an aerodynamic diameter of ≤0.5 μm), as well as PM10 during the combustion of Zhundong coal in air and oxy-fuel conditions (O2/CO2) at three characterized O2 input fractions, i.e., 21, 27 and 32 vol.%. The combustion experiments were carried out in a high-temperature drop-tube furnace (HDTF) at a combustion temperature of 1500 °C. The results show that PM0.5 is composed of Na, S, Mg and Ca, with total fractions of ~90%, while PM0.5–10 (with an aerodynamic diameter between 0.5 and 10 μm) predominantly contains Ca (~50–65%). At three characterized oxygen fractions during oxy-fuel combustion (OXY21, 27 and 32), the promoted O2 fraction was found to increase the yields of both PM0.5 and PM0.5–10. A higher particle-burning temperature and a lower CO2 fraction promote the reactions of both organically bound elements and inorganic minerals, increasing the partitioning of Mg and Ca and causing an increased yield of PM0.5. The yield of PM0.5 from air is high and similar to that from OXY32 while the yield of PM0.5–10 from air is similar to that from OXY27. The high yield of PM0.5 from air is mainly generated by the highest yields of Ca in four conditions.

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“…The bulk ash elemental composition was analyzed by SEM/EDS, while its mineralogy was characterized by CCSEM and XRD. Because the mineralogy determined by CCSEM is classified according to particle elemental composition, it has the advantage to analyze mineralogy of both crystalline and amorphous minerals . With regard to the XRD, it can give complementary information on the crystalline mineral species.…”

Section: Resultsmentioning

confidence: 99%

“…21 −23 The details of CCSEM analysis procedures can be found in our previous work. 24 The crystalline species in the bulk ash was characterized by X-ray diffraction (XRD, X'Pert PRO). To quantify the amounts of amorphous phases in the ash, about 15% corundum was added as an internal standard, which was also adopted by Hosseini et al 25 Peak identification and crystalline mineral quantification were accomplished with the software SIROQUANT.…”

Section: Methodsmentioning

confidence: 99%

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Impact of Oxy-fuel Combustion on Ash Properties and Sintering Strength Development

Liu

et al. 2018

Energy Fuels

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For a successful implementation of the oxy-fuel combustion technology, a good understanding of ash-related issues has to be achieved. Knowledge is still lacking on how oxy-fuel combustion can affect ash properties and its sintering behavior. These are the focus of the present work. Combustion experiments of a sub-bituminous coal were carried out in a drop-tube furnace at 1573 K and under air and different oxy-fuel conditions (i.e., OXY21, 21 vol % O2/79 vol % CO2; OXY27, 27 vol % O2/73 vol % CO2; and OXY32, 32 vol % O2/68 vol % CO2). The bulk ash samples were collected and subjected to analyses by techniques such as computer-controlled scanning electron microscopy, X-ray diffraction, and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy. Sintering tests of the bulk ashes were performed at temperatures ranging from 1023 to 1223 K. The compressive strength of sintered ash was characterized. The results show that oxy-fuel combustion has significant impacts on ash speciation rather than its elemental composition. Ash particle size distributions are also affected, which is mainly attributed to changes in char burning temperatures. Oxy-fuel combustion seems to have insignificant effects on the temperature at which the ash pellet starts to sinter but apparently affects the ash sintering strength. In comparison to the ash from air combustion (AIR ash), the OXY21 ash has a much higher sintering strength. Nevertheless, a decrease of the sintering strength is observed for the OXY27 and OXY32 ashes compared to the OXY21 ash. Such differences are attributed to changes in ash chemical properties.

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The melting potential of various ash components generated from coal combustion: Indicated by the circularity of individual particles using CCSEM technology

Cited by 29 publications

References 39 publications

Ash Formation and Deposition in Oxy-fuel Combustion of Rice Husk, Coal, and Their Blend with 70% Inlet O₂

Ash Formation and Deposition in Oxy-fuel Combustion of Rice Husk, Coal, and Their Blend with 70% Inlet O₂

Emission Behaviors of Inorganic Ultrafine Particles during Zhundong Coal Oxy-Fuel Combustion with Characterized Oxygen Input Fractions Comparable to Air Combustion

Impact of Oxy-fuel Combustion on Ash Properties and Sintering Strength Development

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The melting potential of various ash components generated from coal combustion: Indicated by the circularity of individual particles using CCSEM technology

Cited by 29 publications

References 39 publications

Ash Formation and Deposition in Oxy-fuel Combustion of Rice Husk, Coal, and Their Blend with 70% Inlet O2

Ash Formation and Deposition in Oxy-fuel Combustion of Rice Husk, Coal, and Their Blend with 70% Inlet O2

Emission Behaviors of Inorganic Ultrafine Particles during Zhundong Coal Oxy-Fuel Combustion with Characterized Oxygen Input Fractions Comparable to Air Combustion

Impact of Oxy-fuel Combustion on Ash Properties and Sintering Strength Development

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Ash Formation and Deposition in Oxy-fuel Combustion of Rice Husk, Coal, and Their Blend with 70% Inlet O₂

Ash Formation and Deposition in Oxy-fuel Combustion of Rice Husk, Coal, and Their Blend with 70% Inlet O₂