Combustion characteristics of coal in a mixture of oxygen and recycled flue gas

Tan, Yewen; Croiset, Eric; Douglas, Mark; Thambimuthu, K V

doi:10.1016/j.fuel.2005.08.010

Cited by 364 publications

(180 citation statements)

References 6 publications

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“…However, the conversion mechanism from SO2 to SO3 is rather complicated since it depends on many factors such as flue gas temperature, fuel composition and the amount of excess air [20]. A study of Tan et al [21] shows that the estimated conversion factor of SO2 to SO3 could be as high as 5 percent depending on the fuel. Thus, this study will use the conversion factor of 5 percent to estimate the amount of SO3 in the flue gas.…”

Section: Acid Dew Pointmentioning

confidence: 99%

An Energy Analysis of a Slab Preheating Chamber for a Reheating Furnace

Kangvanskol¹,

Tangthieng²

2014

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Abstract. The iron and steel industry is one of the major industries for developing countries, and it is ranked as one of the industrial sectors that have the highest energy consumption. It is also served as a primary industry that provides materials to secondary industries as well. This present study focuses on a slab, a product from a steelmaking process, which will be sent to a hot-rolling mill to form a final product. Before the rolling process, slab is heated to a proper temperature by charging into a reheating furnace. Heat is generated by a combustion process from direct-fired burners. In general, heat loss from the reheating furnace occurs by several mechanisms including the flue gas loss. Although a recuperator is used to reduce heat loss by recovering some of that to preheat the combustion air, the exit flue gas temperature is still as high as 350-450C. This research paper aims for the investigation of the energy efficiency resulted from the implementation of a slab preheating chamber before charging into a reheating furnace. Four different sizes of the preheating chamber are selected as the case studies for the energy analysis. Another consideration includes the acid dew point of the flue gas as the lowest criteria for the flue gas temperature. The result indicates that the flue gas temperatures are above the acid dew point for all four cases under consideration. The slab temperatures increase from the ambient temperature of 30 o C to 59.52 o C, 75.98 o C, 84.98 o C and 89.46 o C, respectively, before begin charged into the reheating furnace. As a result, the fuel energy consumption after the implementation of the reheating chamber is reduced by 0.94%, 1.46%, 1.75% and 1.89%, respectively comparing to the furnace without the reheating chamber. The reheating furnace efficiency also increases from 69.88% to 70.54%, 70.92%, 71.13% and 71.22%, respectively.

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Section: Acid Dew Pointmentioning

confidence: 99%

An Energy Analysis of a Slab Preheating Chamber for a Reheating Furnace

Kangvanskol¹,

Tangthieng²

2014

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“…The gas environment experienced by pulverized coal particles under oxyfuel combustion is different from the conditions experi enced under standard air combustion, which may impact the com bustion processes including ignition [10,11], combustion characteristics [5,10,12], char reactivity under high CO 2 concentra tions [9,13,14], and pollutant formation [5,12,15 18]. The conse quence of these may become important when the pulverized fuel boilers are planned to be retrofitted to oxyfuel.…”

Section: Introduction and Scope Of Workmentioning

confidence: 99%

Study of ash deposition during coal combustion under oxyfuel conditions

Fryda

Sobrino

Glazer

et al. 2012

Fuel

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a b s t r a c tThis paper presents a comparative study on ash deposition of two selected coals, Russian coal and lignite, under oxyfuel (O 2 /CO 2 ) and air combustion conditions. The comparison is based on experimental results and subsequent evaluation of the data and observed trends. Deposited as well as remaining filter ash (fine ash) samples were subjected to XRD and ICP analyses in order to study the chemical composition and mineral transformations undergone in the ash under the combustion conditions. The experimental results show higher deposition propensities under oxyfuel conditions; the possible reasons for this are investigated by analyzing the parameters affecting the ash deposition phenomena. Particle size seems to be larger for the Russian coal oxy fired ash, leading to increased impaction on the deposition surfaces. The chemical and mineralogical compositions do not seem to differ significantly between air and oxyfuel conditions.The differences in the physical properties of the flue gas between air combustion and oxyfuel combus tion, e.g. density, viscosity, molar heat capacity, lead to changes in the flow field (velocities, particle tra jectory and temperature) that together with the ash particle size shift seem to play a role in the observed ash deposition phenomena.

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“…Such changes have impacts on the combustion processes of coal particles including devolatilization and ignition, [3] flame propagation, [4,5] char combustion [6] and combustion characteristics. [7,8] While transformations of coal minerals are intimately associated with coal particle combustion processes, the changes from air combustion to oxy-fuel combustion also have impacts on mineral transformations and ash formation behaviors. [9,10] Iron has been identified to be a dominant factor contributing to slagging on water wall of pulverized coal-fired furnace.…”

Section: Introductionmentioning

confidence: 99%

Transformation behaviors of excluded pyrite during O₂/CO₂ combustion of pulverized coal

Sheng

Lin

et al. 2009

Asia-Pacific J Chem Eng

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The article was addressed to the transformation of excluded pyrite during O 2 /CO 2 combustion of pulverized coal. Raw pyrite mineral was added to a pulverized coal sample, which was density fractionated to remove the excluded minerals, to simulate the excluded pyrite present in coal. The mixed sample was burned in a drop tube furnace in O 2 /CO 2 and O 2 /N 2 conditions to generate the residue ash, which was characterized by Mössbauer spectroscopic and size analyses. It was found that, in comparison with O 2 /N 2 combustion at the same oxygen concentration, slightly less iron glass silicate was formed from excluded pyrite and silicates although the transformation of pyrite to oxides was slowed in O 2 /CO 2 combustion, different from the behaviors of included pyrite in pulverized coal those were observed in previous study. Additionally, less fragmentation of excluded pyrite particles was also observed in O 2 /CO 2 combustion.

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Combustion characteristics of coal in a mixture of oxygen and recycled flue gas

Cited by 364 publications

References 6 publications

An Energy Analysis of a Slab Preheating Chamber for a Reheating Furnace

An Energy Analysis of a Slab Preheating Chamber for a Reheating Furnace

Study of ash deposition during coal combustion under oxyfuel conditions

Transformation behaviors of excluded pyrite during O₂/CO₂ combustion of pulverized coal

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Combustion characteristics of coal in a mixture of oxygen and recycled flue gas

Cited by 364 publications

References 6 publications

An Energy Analysis of a Slab Preheating Chamber for a Reheating Furnace

An Energy Analysis of a Slab Preheating Chamber for a Reheating Furnace

Study of ash deposition during coal combustion under oxyfuel conditions

Transformation behaviors of excluded pyrite during O2/CO2 combustion of pulverized coal

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Product

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Transformation behaviors of excluded pyrite during O₂/CO₂ combustion of pulverized coal