Application of Reburning for NOx Control to a Firetube Package Boiler

Mulholland, James A.; Lanier, W.S.

doi:10.1115/1.3239796

Cited by 11 publications

(7 citation statements)

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“…Other studies (Kelly et al, 1986;Lanier et al, 1986; showed no clear optimum as the reburn zone stoichiometry decreased. The results of Lanier et al (1986), Mulholland and Lanier (1985) and Mulholland and Hall (1986) in a package boiler simulator suggest that an optimum reburning effectiveness might be obtained at reburn zone stoichiometries below . 0.7.…”

Section: Rebum Zon¢_stoichiometry_mentioning

confidence: 96%

Nitrogen oxide abatement by distributed fuel addition. Final report

Wendt¹,

Mereb²

1991

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Reburning is examined as a means of NOx destruction in a 17 kW down-fired pulverized coal combustor. In reburning, a secondary fuel is introduced downstream of the. primary flame to produce a reducing zone, favorable td NO destruction, and air is introduced further downstream to complete the combustion. Emphasis is on natural gas reburning and a bituminous coal primary flame. A parametric examination of reburning • employing a statistical experimental design, is conducted, complemented by detailed experiments. Mechanisms governing the inter-conversion of nitrogenous species in the fuel rich reburn zone are explored. The effect of reburning on N20 emissions, the effect of primary flame mode (premixed and diffusion) and the effect of distributing the reburning fuel, are also investigated. The parametric study allowed the effects of significant reburning variables to be identified and examined, but these effects could not be quantified. Detailed experiments identified optimum reburn zone stoichiometry between 0.8 and 0.9, depending on mixing in the reburn zone. Overall NO reductions, as high as 80%, were possible and depended mainly on reburn zone variables, namely, temperature, residence time and stoichiometry. ,I Exhaust N20 emissions increased after air addition in the final stage of reburning, but were less than 10 ppm. Lower reductions in NO emissions were obtained when the primary flame was of the diffusion type, rather than of the prernixed type, but final NO emissions below 250 ppm (dry, 0% O2) were still possible. Reburning fuel introduction in multiple streams did not enhance NO destruction, relative to single stream injections. Within the reburn zone, rebuming mechanisms ocbarred in two regimes. One regime was in the vicinity of the rebuming fuel flame and was distinguished by fast reactions between NO and hydrocarbons that were limited by mixing. The other regime covered the remainder of the reburn zone and was distinguished by slower reactions, without mixing complications. For the latter regime, a simplified model based on detailed gas phase chemical kinetic mechanisms .and known rate coefficiems was able to predict temporal profiles of NO, HCN and NII 3. Reactions involving hydrocarbons played important roles in both regimes and N2 fixation by hydrocarbons limited reburning effectiveness at low primary NO values. Appropriate corrections for mixing effects in early time scales of the reburn zone allowed the prediction of nitrogenous species profiles from primary NO values, as well as overall reburning effectiveness.

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Section: Rebum Zon¢_stoichiometry_mentioning

confidence: 96%

Nitrogen oxide abatement by distributed fuel addition. Final report

Wendt¹,

Mereb²

1991

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“…To illustrate the scope of issues involved, a brief review of several recent investigations is given. Ishikawajima-Harma (1983, Mulholland andHall (1985) and Mulholland and Lanier (1985) of AcurexEPA, Greene, McCarthy, and Overmoe from EER (1985), and Mulholland and Hall of AcurexEPA (1987). This research yielded slightly different results as to the applicability of different fossil hels as a reburn fuel.…”

Section: -3mentioning

confidence: 99%

Demonstration of natural gas reburn for NO{sub x} emissions reduction at Ohio Edison Company`s cyclone-fired Niles Plant Unit Number 1

Borio¹,

Lewis²,

Koucky³

et al. 1996

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“…However the reburning concept accomplishing fifty percent NO removal was reported only in 1983, when x Takahashi et al (1983) reported results using natural gas as a reburning fuel. Mulholland and Lanier (1984) studied NO control by reburning in a firetube package boiler. Energy and x Environment Research Corporation (Greene and Weaver, 1974;Overmoe et al 1986), and U.S. Environmental Protection Agency (Mulholland and Hall.…”

Section: Current Reburning Research Projectsmentioning

confidence: 99%