Determination of Char Oxidation Rates with Different Analytical Methods

Lee, Byoung-Hwa; Song, Juhun; Kang, Ki-Tae; Chang, Young-June; Jeon, Chung-Hwan

doi:10.3795/ksme-b.2009.33.11.876

Cited by 8 publications

(2 citation statements)

References 10 publications

(1 reference statement)

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“…Those have their own merits and limitations due to an inherent assumption derived for the corresponding rate expression as discussed in Ref. [26]. Recognizing the fact that the rate expression in Eq.…”

Section: Appendixmentioning

confidence: 98%

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Examination of flame length for burning pulverized coal in laminar flow reactor

Kim

Chang

et al. 2010

J Mech Sci Technol

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Because there has been a recent increase in the use of low calorific coal compared to standard coal, it is crucial to control the char flame length governing the burning life-time of coal in a coal-fired utility boiler. The main objective of this study is to develop a simplified model that can theoretically predict the flame length for burning coal in a laboratory-scale entrained laminar flow reactor (LFR) system. The char burning behavior was experimentally observed when sub-bituminous pulverized coal was fed into the LFR under burning conditions similar to those in a real boiler: a heating rate of 1000 K/s, an oxygen molar fraction of 7.7 %, and reacting flue gas temperatures ranging from 1500 to 2000 K. By using the theoretical model developed in this study, the effect of particle size on the coal flame length was exclusively addressed. In this model, the effect of particle mass was eliminated to compare with the experimental result performed under a constant mass feeding of coal. Overall, the computed results for the coal flame length were in good agreement with the experimental data, particularly when the external oxygen diffusion effect was considered in the model.

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Section: Appendixmentioning

confidence: 98%

“…The carbon consumption rate, `, c unit area r , which is equal to the char burning rate per unit area, was experimentally determined in the same LFR apparatus from the change in a measured particle's radius, from its initial value of 0 r to t r during a burn-off process [26][27][28]. It can be expressed by:…”

Section: Appendixmentioning

confidence: 99%

Examination of flame length for burning pulverized coal in laminar flow reactor

Kim

Chang

et al. 2010

J Mech Sci Technol

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Effect of Coal Blending Methods with Different Excess Oxygen on Unburned Carbon and NO_x Emissions in an Entrained Flow Reactor

2012

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The influence of coal blending methods, such as out-furnace (external or premixed) blending and in-furnace (initially nonmixed) blending, with different excess oxygen (highest, medium, and lowest stoichiometric conditions) on unburned carbon and NO x emissions of blend combustion in an entrained flow reactor has been analyzed, using experimental and numerical approaches for binary coals used by Korean power plants. The results confirm that, under the medium condition, contrasting processes, such as reactive and unreactive effects, occur with SBRs in the out-furnace blending method. The in-furnace blending method results in an improvement in the efficiency of unburned carbon fractions and a further reduction in the NO x emission. Under the highest condition, the unburned carbon fraction in both the out-furnace and the in-furnace blending methods corresponds with the tendency under the medium condition with contrasting processes of lower magnitude, whereas the NO x emission in the highest condition increases slightly. Under the lowest conditions, the unburned carbon fraction in the out-furnace blending method gradually decreases as SBR decreases, without a competition effect. The reduction of NO x emission under the lowest conditions is more effective than those under other conditions for the two blending methods because of homogeneous and heterogeneous NO x reduction mechanisms. These results show that the phenomenon that occurs with coal blending methods under different excess oxygen conditions has been demonstrated and the in-furnace blending method below medium conditions would be an effective method to improve combustibility and NO x emission due to penalty of NO x under the highest condition. In general, the numerical results are in agreement with the measured values and give insight into the phenomena that affect the blending methods under different excess oxygen conditions.

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Char Oxidation Characteristics of Ashless Coal in Drop Tube Furnace

An¹,

Lee²,

Kim³

et al. 2012

Transactions of the Korean Society of Mechanical Engineers B

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Determination of Char Oxidation Rates with Different Analytical Methods

Abstract: Char oxidation experiments were performed with a sub-bituminous roto-middle coal in the Drop Tube Furnace (DTF) at atmospheric pressure condition. While temperatures varied between 900, 1100, 1400, particle ℃

Cited by 8 publications

References 10 publications

Examination of flame length for burning pulverized coal in laminar flow reactor

Examination of flame length for burning pulverized coal in laminar flow reactor

Effect of Coal Blending Methods with Different Excess Oxygen on Unburned Carbon and NO_x Emissions in an Entrained Flow Reactor

Char Oxidation Characteristics of Ashless Coal in Drop Tube Furnace

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Determination of Char Oxidation Rates with Different Analytical Methods

Abstract: Char oxidation experiments were performed with a sub-bituminous roto-middle coal in the Drop Tube Furnace (DTF) at atmospheric pressure condition. While temperatures varied between 900, 1100, 1400, particle ℃

Cited by 8 publications

References 10 publications

Examination of flame length for burning pulverized coal in laminar flow reactor

Examination of flame length for burning pulverized coal in laminar flow reactor

Effect of Coal Blending Methods with Different Excess Oxygen on Unburned Carbon and NOx Emissions in an Entrained Flow Reactor

Char Oxidation Characteristics of Ashless Coal in Drop Tube Furnace

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Effect of Coal Blending Methods with Different Excess Oxygen on Unburned Carbon and NO_x Emissions in an Entrained Flow Reactor