Effects of NO Models on the Prediction of NO Formation in a Regenerative Furnace

Ishii, Takao; Zhang, C.; Sugiyama, S.

doi:10.1115/1.1318205

Cited by 19 publications

(13 citation statements)

References 12 publications

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“…(2) The rate of the reaction for NO x is slower than that of the combustion reaction. Thus, the NO x mechanism can be decoupled from the main combustion mechanism [47]. (3) NO x chemistry displays a negligible influence on the predicted flow field, temperature, and major combustion product concentrations [48].…”

Section: No X Modelmentioning

confidence: 99%

Numerical study of hydrogen-enriched methane-air combustion under ultra-lean conditions

Mokheimer

Sanusi

Habib

2016

Int. J. Energy Res.

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SUMMARYThe demand for gas turbines that accept a variety of fuels has continuously increased over the last decade. Understanding the effects of varying fuel compositions on combustion characteristics and emissions is critical to designing fuel-flexible combustors. In this study, the combustion characteristics and emissions of methane and hydrogen-enriched methane were both experimentally and numerically investigated under ultra-lean conditions (Ø ≤ 0.5). This study was performed using global mechanisms with a one-step mechanism by Westbrook and Dryer and a two-step mechanism with an irreversible and reversible CO/CO 2 step (2sCM1 and 2sCM2). Results show that the 2sCM2 mechanism under-predicted the temperature, major species, and NO x by more than 100% under ultra-lean conditions; thus, we proposed a modified-2sCM2 mechanism to better simulate the combustion characteristics. The mechanisms of Westbrook, 2sCM1, and modified 2sCM2 predicted the temperature and the CO 2 emission with an average deviation of about 5% from the experimental values. Westbrook and 2sCM1, however, over-predicted the NO x emission by approximately 81% and 152%, respectively, as compared with an average under-prediction of 11% by the modified-2sCM2 mechanism. The numerical results using the proposed modified-2sCM2 mechanism shows that the presence of hydrogen in the fuel mixture inhibits the oxidation of methane that led to the formation of unburned hydrocarbons in the flame. We also showed that for any given fuel compositions of H 2 /CH 4 , there is an optimum equivalence ratio at which the pollutant emissions (CO and NO x ) from the combustor are minimal. Zero CO and 5 ppm NO x emissions were observed at the optimal equivalence ratio of 0.45 for a fuel mixture containing 30% H 2 . The present study provides a basis for ultra-lean combustion toward achieving zero emissions from a fuel-flexible combustor.

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Section: No X Modelmentioning

confidence: 99%

Numerical study of hydrogen-enriched methane-air combustion under ultra-lean conditions

Mokheimer

Sanusi

Habib

2016

Int. J. Energy Res.

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“…Some researchers have studied NO x emissions from other industrial furnaces. Ishii et al [17] have built a numerical model to investigate the NO x emissions in a regenerative furnace, in this model three chemical kinetic processes for NO x formation are included. Khalilarya and Lotfiani [18] have provided a numerical study of flow pattern and its effect on NO x emissions in a single chamber square tangentially fired furnace.…”

Section: Introductionmentioning

confidence: 99%

Numerical study on characteristics of combustion and pollutant formation in a reheating furnace

Wang

et al. 2018

Therm sci

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Original scientific paper https://doi.org/10.2298/TSCI180118277QEnergy consumption of fuel-fired industrial furnace accounts for about 23% of the national total energy consumption every year in China. Meanwhile, the reduction of combustion-generated pollutants in furnace has become very important due to the stringent environment laws and policy introduced in the recent years. It is therefore a great challenge for the researchers to simultaneously enhance the fuel efficiency of the furnace while controlling the pollution emission. In this study, a transient 3-D mathematical combustion model coupled with heat transfer and pollution formation model of a walking-beam-type reheating furnace has been developed to simulate the essential combustion, and pollution distribution in the furnace. Based on this model, considering nitrogen oxides formation mechanism, sensitivity study has been carried out to investigate the influence of fuel flow rate, air-fuel ratio on the resultant concentration of nitrogen oxides in the flue gas. The results of present study provide valuable information for improving the thermal efficiency and pollutant control of reheating furnace.

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“…Ishii et al [1,2] showed that 1579 K of preheat inlet air temperature can be obtained in a regenerative furnace. Meanwhile, it produced low NO x emissions and over 70% heating efficiency.…”

Section: Introductionmentioning

confidence: 99%

Two Dimensional Thermal-Hydraulic Analysis for a Packed Bed Regenerator Used in a Reheating Furnace

2016

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Packed bed is widely used for different industries and technologies, such as heat exchangers, heat recovery, thermal energy storage and chemical reactors. In modern steel industry, packed bed regenerator is widely utilized in the reheating furnace to increase the furnace efficiency. This study established a two dimensional numerical model to simulate a packed bed used in regenerative furnaces. The physical properties of fluids and packed stuffing (such as density, thermal conductivity, and specific heat) are considered as functions of temperature to adapt the large temperature variation in operation. The transient temperature profiles of the flue gas, packed bed, and air during the heating and regeneration period are examined for various switching time (30, 60, 120, and 240 s). The results reveal that, during the heating period, the spanwise averaged heat transfer coefficient is decreased along the longitudinal downstream direction, while during the regeneration period, the opposite trend is true. Moreover, the regenerator thermal effectiveness is decreased by increasing the switching time.

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Effects of NO Models on the Prediction of NO Formation in a Regenerative Furnace

Cited by 19 publications

References 12 publications

Numerical study of hydrogen-enriched methane-air combustion under ultra-lean conditions

Numerical study of hydrogen-enriched methane-air combustion under ultra-lean conditions

Numerical study on characteristics of combustion and pollutant formation in a reheating furnace

Two Dimensional Thermal-Hydraulic Analysis for a Packed Bed Regenerator Used in a Reheating Furnace

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