NO  emission characteristics of confined jet nonpremixed flames

Noda, Susumu; Inohae, Junya; Saldi, Zaki S.

doi:10.1016/j.proci.2006.07.088

Cited by 20 publications

(21 citation statements)

References 8 publications

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“…With regard to the relationship between NOx emissions and the recirculated burned gas, Noda and co-workers (Noda et al, 2007, Nada et al, 2008 investigated the effect of dilution resulting from burned gas recirculation on NOx emissions from laboratory-scale cylindrical furnaces with different diameters and found that a large furnace diameter enhances the extent of dilution. Noda's result suggests another cause for the reverse trend seen in the present study, in terms of the cross-sectional furnace size.…”

Section: And 6) This Difference Between Einox Valuesmentioning

confidence: 99%

Effect of the distance between fuel and oxidizer nozzles on NOx emissions from spray combustion furnaces incorporating high-temperature preheated oxidizers

Nada

Shibata

Imaoka

et al. 2015

JTST

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The objective of the present study was to investigate the effect of the distance between fuel and oxidizer nozzles on NOx emissions from a laboratory-scale spray combustion furnace simulating an industrial high-temperature air combustion (HiTAC) furnace. The furnace employed in these trials was fueled with commercially obtainable kerosene in combination with highly preheated oxidizer gases. The oxidizer was pre-diluted by the addition of nitrogen in order to produce dilution levels equivalent to those in industrial HiTAC furnaces. The resulting NOx measurements indicate a trend opposite to that reported by previous studies, such that increasing the distance between the nozzles increases the NOx emissions, and a theory is advanced to explain this unusual observation. In a furnace within which the nozzle distance in the burner is small, the properties of the oxidizer supplied from the nozzle located near the spray nozzle greatly affect NOx emissions. The use of an oxidizer with a much lower preheat temperature and a lower O 2 concentration induces flame lifting further downstream, which significantly reduces NOx emissions through the formation of an invisible flame exhibiting a uniform temperature distribution throughout the furnace. In contrast, in a furnace in which the burner has a large nozzle distance, a highly luminous flame is anchored near the spray nozzle exit due to ignition of fuel vapor by high-temperature burned gases recirculated to the lower section of the furnace. This flame represents a zone with high combustion intensity and generates significant NOx emissions. In such cases, the influence of the oxidizer properties is moderated due to the widely separated nozzle locations.

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Section: And 6) This Difference Between Einox Valuesmentioning

confidence: 99%

Effect of the distance between fuel and oxidizer nozzles on NOx emissions from spray combustion furnaces incorporating high-temperature preheated oxidizers

Nada

Shibata

Imaoka

et al. 2015

JTST

View full text Add to dashboard Cite

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“…(6) , the details of which are presented, and then is herein explained in terms of evaluation of radiation and measurement of flow fields. Furnaces are cylindrical and a burner is set at the center of the bottom of the furnaces.…”

Section: Experimental Apparatusmentioning

confidence: 99%

“…In this paper, a limited number of data are presented in order to facilitate discussion and because of the space limitation. which should be generated around the furnace base, may play an important role in mixing in furnace combustion (6) . The flame stretch acts to cool the flame.…”

Section: Experimental Apparatusmentioning

confidence: 99%

“…3 is denoted as Q max , and may qualitatively indicate the amount of burnt gases entrained in to the jet zone. Noda et al (6) introduced a parameter…”

Section: Entrainment Characteristicsmentioning

confidence: 99%

“…An investigation of the EINOx characteristics of confined flames was conducted by Noda et al (6) , and showed that EINOx would significantly decrease by the increasing the inner diameter of the furnace, turbulence at the flame boundary, and global equivalence ratio. This indicated that the geometric combination of burner and furnace is an important factor to reduce the NOx emission.…”

Section: Introductionmentioning

confidence: 99%

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NOx Reduction of Non-Premixed Flames by Combination of Burner and Furnaces

Somarathne

Parwatha

Oguri

et al. 2013

JEE

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This study proposes an idea of NOx reduction and high efficiency combustion by combination of burner and furnace. This is basically attributed to the use of entrainment of burnt gases to flame in furnace. The entrainment of burnt gases leads the dilution of flame and the recovery of heat to be exhausted. The phenomena are strongly related to the geometry of burner and furnace. The temperature, concentration, and flow field characteristics were investigated for piloted propane non-premixed flames in the cylindrical furnaces in terms of NOx emission. The effects of the furnace inner diameter, D 1 , air inlet velocity difference, ∆U a , and global equivalence ratio,φ, on NOx emission were investigated.Moreover, two kinds of materials: Pyrex glass and stainless steel were used as the furnace wall to evaluate the radiation effect through the comparison of the flame characteristics. The emission index of NOx, EINOx, decreases roughly with the increase of above parameters. This decrease is observed to be a consequence of dilution by the burnt gases and flame stretch. The dilution is attributed to the recirculation structure, which is formed at the bottom of the furnace. The flame stretch is related to the velocity difference, which is introduced by multiple air inlets. The EINOx of confined non-premixed flame is scaled by the parameter D 1 U F ∆U a , which is proportional to Re,cDa -1 . Here, U F is the fuel velocity, Re,c is the furnace Reynolds number reflecting the turbulence in the furnace, and Da is the Damköhler number reflecting the flame stretch. The parameter D 1 U F ∆U a is related linearly to the volume flow rate entrained in to the flame. Thus, this study verified that the EINOx of confined non-premixed flame is dominated primarily from the entrainment of burnt gases by the recirculation vortex and secondarily by the turbulence at the flame boundary, which is generated by the air velocity difference. In addition, it is found that under present experimental conditions, the radiation effect on the EINOx is small and constant with respect to the parameters. Thus, this idea has a potential for practical applications.

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