Numerical study of H 2 O addition effects on pulverized coal oxy-MILD combustion

Tu, Yaojie; Liu, Hao; Su, Kai; Chen, Sheng; Liu, Zhaohui; Chen, Zheng; Li, Weijie

doi:10.1016/j.fuproc.2015.05.031

Cited by 63 publications

(21 citation statements)

References 52 publications

(99 reference statements)

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“…The detailed configuration of the furnace is shown in Figure 1, which is first studied by the International Flame Research Foundation (IFRF) and subsequently adopted in many research works. [5][6][7][8][9]25,26 The burner consists of a central secondary air inlet (Ø 125 mm) and two primary air inlets (Ø 27.3 mm), through which flue gas from another combustor and nonpreheated air carrying coal particles are injected, respectively. Pure oxygen is added to the secondary air stream to maintain a similar O 2 concentration with the primary air stream.…”

Section: The Ifrf Furnace and The Implementation Of Fuel-rich/lean mentioning

confidence: 99%

“…[2][3][4][5][6][7][8][9][10][11][12][13] The essence of this technology for coal combustion is to achieve strong recirculation of the injected streams so that the coal particles are heated and combusted in a highly substoichiometric condition. [2][3][4][5][6][7][8][9][10][11][12][13] The essence of this technology for coal combustion is to achieve strong recirculation of the injected streams so that the coal particles are heated and combusted in a highly substoichiometric condition.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the potential of significant reduction of NO x emission, moderate or intense low-oxygen dilution (MILD) combustion has become a hot topic within the combustion committee worldwide and has been studied intensively. [2][3][4][5][6][7][8][9][10][11][12][13] The essence of this technology for coal combustion is to achieve strong recirculation of the injected streams so that the coal particles are heated and combusted in a highly substoichiometric condition. 14 As a result, the peak temperature is reduced, and thermal-NO formation is mitigated.…”

Section: Introductionmentioning

confidence: 99%

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Numerical study of further NO _x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology

Zeng

et al. 2019

Int J Energy Res

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Summary This paper numerically examines the feasibility of further reducing NOx emission from a semi‐industrial scale coal MILD (moderate and intense low‐oxygen dilution) combustion furnace by adopting fuel‐rich/lean technology. The implementation is achieved by separating the original fuel jet into two parallel jets which will be used as rich and lean streams. An effort has been made to develop a 13‐step reaction mechanism and NOx evolution UDFs (user defined functions) for better understanding the interactions between MILD combustion and fuel‐rich/lean technology. The experiment of the reference case (Combustion and Flame 156.9 (2009): 1771‐1784) is well reproduced by the present numerical simulation, indicating high reliability of developed models. The validity of the further reduction of NOx emission is assessed by the comparison among inner‐fuel‐rich (IFR), outer‐fuel‐rich (OFR), and reference cases resulting from the adjustment of the fuel supply through the two fuel‐rich/lean jets. The results show that both IFR and OFR configurations succeed in achieving further reduction of NOx emission as compared with the reference case, which stems from both thermal and fuel paths. Specifically, the decrease of thermal‐NO emission originates from the contraction of high‐temperature regions (>1800 K), where nearly 94% reduction occurs within the temperature range of 1800 K and 1950 K while only 6% within 1950 K and 2030 K despite their high temperature sensitivity. The reduction of the fuel‐NO emission is mainly attributed to the promoted NO reduction on char surface and neutralization with HCN and NH3. Generally, the NOx emission can be minimized by enlarging the equivalence ratio difference between rich and lean jets, and the OFR configuration exhibits a higher potential than the IFR counterparts. However, since a relatively high temperature (1623 K) secondary air was used in the experiment, the maximum NOx reduction potential was limited to only 2.5%.

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Section: The Ifrf Furnace and The Implementation Of Fuel-rich/lean mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical study of further NO _x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology

Zeng

et al. 2019

Int J Energy Res

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“…H 2 O addition improves H 2 and CO concentrations, promoting the NO reduction via the following reactions:

2 NO + H_{2} \to 2 HNO,

2 HNO + H_{2} \overset{fast}{\to} 2 H_{2} normalO + N_{2},

NO + CO \to normalN + {CO}_{2},

NO + normalN \to N_{2} + normalO .

The amounts of H/OH radicals are also increased in a H 2 O atmosphere, and H/OH radicals are conducive to the reduction of NO by NH i via the following reactions:

normalO + H_{2} normalO \to 2 OH,

normalH + H_{2} normalO \to OH + H_{2},

{NH}_{3} + OH \to {NH}_{2} + H_{2} normalO,

{NH}_{2} + NO \to N_{2} + H_{2} normalO .

Moreover, H 2 O increases the generation of aliphatic hydrocarbons, promoting the NO reduction . Tu et al numerically demonstrated that the reduction reaction of NO with H 2 was reinforced in O 2 /H 2 O atmosphere during coal combustion.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of the combustion and NO emission behaviors during cofiring coal and biomass in O₂/N₂ and O₂/H₂O

Zhou

et al. 2018

Asia-Pacific J Chem Eng

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“…Their work confirms that the particle characteristics, the devolatilization and char burnout models are crucial in the prediction of combustion performance. The chemical species concentrations in the combustion process [28][29][30] and the temperature distribution [31][32][33][34] within the combustion chamber are the key features that a numerical model is able to describe in detail. Commonly, the two-phase flow, with the solid phase dispersed in the continuous phase, is numerically solved by means of an Eulerian-Lagrangian approach with one-or two-way coupling between the two phases.…”

Section: Introductionmentioning

confidence: 99%

Assessment against Experiments of Devolatilization and Char Burnout Models for the Simulation of an Aerodynamically Staged Swirled Low-NOx Pulverized Coal Burner

et al. 2017

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Abstract:In the next few years, even though there will be a continuous growth of renewables and a loss of the share of fossil fuel, energy production will still be strongly dependent on fossil fuels. It is expected that coal will continue to play an important role as a primary energy source in the next few decades due to its lower cost and higher availability with respect to other fossil fuels. However, in order to improve the sustainability of energy production from fossil fuels, in terms of pollutant emissions and energy efficiency, the development of advanced investigation tools is crucial. In particular, computational fluid dynamics (CFD) simulations are needed in order to support the design process of low emission burners. Even if in the literature several combustion models can be found, the assessment of their performance against detailed experimental measurements on full-scale pulverized coal burners is lacking. In this paper, the numerical simulation of a full-scale low-NO x , aerodynamically-staged, pulverized coal burner for electric utilities tested in the 48 MW th plant at the Combustion Environment Research Centre (CCA -Centro Combustione e Ambiente) of Ansaldo Caldaie S.p.A. in Gioia del Colle (Italy) is presented. In particular, this paper is focused on both devolatilization and char burnout models. The parameters of each model have been set according to the coal characteristics without any tuning based on the experimental data. Thanks to a detailed description of the complex geometry of the actual industrial burner and, in particular, of the pulverized coal inlet distribution (considering the entire primary air duct, in order to avoid any unrealistic assumption), a correct selection of both devolatilization and char burnout models and a selection of suited parameters for the NO x modeling, accurate results have been obtained in terms of NO x formation. Since the model parameters have been evaluated a priori, the numerical approach proposed here could be suitable to be applied as a performance prediction tool in the design of pulverized coal burners.

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Numerical study of H 2 O addition effects on pulverized coal oxy-MILD combustion

Cited by 63 publications

References 52 publications

Numerical study of further NO _x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology

Numerical study of further NO _x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology

Experimental study of the combustion and NO emission behaviors during cofiring coal and biomass in O₂/N₂ and O₂/H₂O

Assessment against Experiments of Devolatilization and Char Burnout Models for the Simulation of an Aerodynamically Staged Swirled Low-NOx Pulverized Coal Burner

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Numerical study of H 2 O addition effects on pulverized coal oxy-MILD combustion

Cited by 63 publications

References 52 publications

Numerical study of further NO x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology

Numerical study of further NO x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology

Experimental study of the combustion and NO emission behaviors during cofiring coal and biomass in O2/N2 and O2/H2O

Assessment against Experiments of Devolatilization and Char Burnout Models for the Simulation of an Aerodynamically Staged Swirled Low-NOx Pulverized Coal Burner

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Numerical study of further NO _x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology

Numerical study of further NO _x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology

Experimental study of the combustion and NO emission behaviors during cofiring coal and biomass in O₂/N₂ and O₂/H₂O