Characterization of NOx, N20, and CO for Lean-Premixed Combustion in a High-Pressure Jet-Stirred Reactor

Steele, Robert C.; Tonouchi, J. H.; Nicol, David G.; Horning, D. C.; Malte, Philip C.; Pratt, David T.

doi:10.1115/1.2818121

Cited by 28 publications

(22 citation statements)

References 12 publications

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“…All NO data are adjusted to a mean residence time of 3.2 ms, assuming NO yield is proportional to residence time in the lean, atmosphaic pressure JSR operated at constant combustion temperature. This follows from the work of Steele (1995) and Steele et al (1998). The main results of Table 2 are those for NOx, which are discussed below in conjunction with Figures 6 and 7.…”

Section: Resultsmentioning

confidence: 59%

NOX as a Function of Fuel Type: C1-to-C16 Hydrocarbons and Methanol

Lee

Malte

Nicol

1999

Volume 2: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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The response of NOx to fuel type is determined for leanprevaporized-premixed combustion in an atmospheric pressure jetstirred reactor (JSR). Pure, straight chain, alkane fuels from C1 (methane) to C16 (hexadecane) and methanol are tested Testing is conducted under three conditions, each of which is obtained using a particular inlet-jet nozzle for the JSR. For a selected condition, the fuels are bunted under nearly identical macroscopic thermal and fluid mechanical fields in the JSR. A constant mixture inlet total temperature is used that provides for complete vaporization of all of the fuels tested without causing pre-flame reactions in the prembud. Two of the nozzles used have single, centered jets and provide a nominal combustion temperature of 1790 K The third nozzle has eight diverging jets. In this case, the fuel-air equivalence ratio is increased, providing a nominal combustion temperature of 1850 K Lowest levels of NOx are measured when methanol is burned Upon switching to methane, the NOx concentration increases by 62±10%. For the &lame fuels, methane combustion yields the lead amount of NOx. Upon switching from methane to ethane, the NO increases by 22±2%. Further increases in the size of the alkane fuel molecule (from C2 ICI C16) show small increases (81:5%) in the NO concentration. Although the JSR-condition selected affects the absolute NOx concentration, the trends in NO x concentration with respect to fuel-type are the same for the three conditions usedThe JSR is modeled as a single perfectly stirred reactor (PSR) operating at the experimental residence time and combustion temperature. This modeling shows that the increase in the NO, measured for the alkane fuels may be explained in terms of the increase in 0-atom concentration with increasing C/H ratio. In order to explore the effect of Fenimore prompt NO x, a two-PSRs-in-series model is used The first PSR is assigned a residence time equal to 5% the total residence time of the reactor. The second PSR accounts for the remaining 95% of the reactor residence time. Because of its short lifetime, the CH radical is effectively restricted to the first PSR, and prompt NOx mainly forms in this zone. Mechanisms directly dependent on the 0-atom form NO x throughout the reactor. The modeling suggests that prompt NOx is responsible for the greater concentration of NOx found in the methane combustion compared to the methanol combustion.

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Section: Resultsmentioning

confidence: 59%

NOX as a Function of Fuel Type: C1-to-C16 Hydrocarbons and Methanol

Lee

Malte

Nicol

1999

Volume 2: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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“…He concluded that the concentration of CH radicals is a significant factor affecting the total NO formation. Prompt mechanism is responsible for NO x formation at low temperatures (Dupont and Williams, 1998;Steele et al, 1998). As the name suggests, N 2 O-intermediate NO formation proceeds through a set of reactions involving N 2 O (Miller and Bowman, 1989).…”

Section: Introductionmentioning

confidence: 99%

Emission Characteristics of Heat Recirculating Porous Burners With High Temperature Energy Extraction

Banerjee

Saveliev

2020

Front. Chem.

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Emission characteristics of heat recirculating porous burners with high temperature heat extraction are studied numerically. Two types of burners are considered: counterflow porous burner (CFB) and reciprocal counterflow porous burner (RCFB). The combustion of methane-air mixtures flowing through the porous media is modeled by solving steady state governing equations to obtain the flame temperature and species profiles. Formation of CO, NO, NO 2 , and NO x is studied in CFB and RCFB in a range of equivalence ratios from 0.3 to 1.0 and heat extraction temperatures from 300 to 1,300 K. The contribution of various NO formation mechanisms is comparatively analyzed and related to the NO generation predicted by a detailed chemistry mechanism. The effect of high temperature heat extraction on the formation of CO and NO x is analyzed. Numerical predictions indicate a constant monotonic decrease of NO x concentration with increasing temperature of energy extraction. The formation of CO is observed to follow the similar trend. For heat extraction at 1,300 K, simulations predicted 3.6 ppm of NO x and 3.9 ppm of CO for CFB and 4.1 ppm of NO x and 3.5 ppm of CO for RCFB when these burners are operated at an equivalence ratio of 0.7.

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“…This study has been undertaken to determine if a jet-stirred reactor operated in lean-premixed (LP) mode at high pressure could attain well-stirred behavior for NOx formation. Initial work by Steele (1995) and Steele et al (19%) on NOx formation in a high-pressure jet-stirred reactor (1P-JSR) showed this not to be the case That is, the NOx was indicated to form non-uniformly in the reactor, mainly in the inlet jet, rather than uniformly, as in a well-stinted reactor (WSR). However, Steele (1995) only examined residence times of 2.0 and 4.0 ms.…”

Section: Introductionmentioning

confidence: 99%

“…Initial work by Steele (1995) and Steele et al (19%) on NOx formation in a high-pressure jet-stirred reactor (1P-JSR) showed this not to be the case That is, the NOx was indicated to form non-uniformly in the reactor, mainly in the inlet jet, rather than uniformly, as in a well-stinted reactor (WSR). However, Steele (1995) only examined residence times of 2.0 and 4.0 ms. In the present work, a reactor, geometrically similar to Steele's, has been operated at 6.5 atm for residence time as low as 0.5 ms, and examined for WSR formation of NOx.…”

Section: Introductionmentioning

confidence: 99%

“…The impact occurs through the nitrous oxide and Zeldovich mechanisms . 0-atom has a lifetime of order 10 ms in atmospheric pressure flames, and consequently it appears possible to operate atmospheric pressure, lean, methane-fired JSR's essentially wellstirred for NOx formation, (Steele et aL, 1996). At high pressure, however, the 0-atom lifetime falls to ogler 1 ms, .…”

Section: Introductionmentioning

confidence: 99%

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NOx Dependency on Residence Time and Inlet Temperature for Lean-Premixed Combustion in Jet-Stirred Reactors

Rutar

Horning

Lee

et al. 1998

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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The effect of the residence time variation on NOx formation in high-intensity, lean-premixed (LP) methane combustion is explored through experiments conducted in a high-pressure jet-stirred reactor (HP-JSR) operated at 6.5 atm pressure. The residence time is varied between 0.5 ms and 4 ms, holding the measured reactor recirculation zone temperature constant at 1803 K. Air preheat is not used. The results indicate a minimum NOx level of 3.5 ppmvd (15% O2) for reactor mean residence times between 2 and 2.5 ms. As the residence time is reduced from 2.0 ms to 0.5 ms, the NOx increases, consistent with a spreading of super-equilibrium concentrations of free-radicals throughout the reactor. For the shortest residence times examined, PSR modeling agrees with the NOx measurements. At long residence times, (i.e., above 2.5 ms), the measured CO behavior indicates the super-equilibrium free radicals, and thus the rapid NOx production, are confined mainly to the jet zone of the reactor. For the long residence time range, the measured NOx increases with increasing residence time, and is significantly less than the PSR predictions. A simple two-zone model of the HP-JSR is used to interpret and evaluate the NOx formation. Experiments exploring the effect of inlet temperature on NOx are conducted in an atmospheric pressure, methane-fired, jet-stirred reactor (A-JSR). The reactor temperature is held constant at 1788 K, and the inlet mixture temperature is varied between the no-preheat case and 623 K. These experiments show that increasing the inlet air temperature over the full range tested decreases the NOx by about 30%. Several explanations are offered for the behavior. For both reactors, i.e., the HP-JSR and A-JSR, single inlet jet nozzles are used. The results lead to a practical conclusion that very low NOx levels can be achieved for combustion in strongly back-mixed reaction cavities adjusted to optimal residence time and inlet temperature.

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Characterization of NOx, N20, and CO for Lean-Premixed Combustion in a High-Pressure Jet-Stirred Reactor

Cited by 28 publications

References 12 publications

NOX as a Function of Fuel Type: C1-to-C16 Hydrocarbons and Methanol

NOX as a Function of Fuel Type: C1-to-C16 Hydrocarbons and Methanol

Emission Characteristics of Heat Recirculating Porous Burners With High Temperature Energy Extraction

NOx Dependency on Residence Time and Inlet Temperature for Lean-Premixed Combustion in Jet-Stirred Reactors

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