NO x Formation in High-Pressure Jet-Stirred Reactors With Significance to Lean-Premixed Combustion Turbines

2002 ◽  
Vol 124 (4) ◽  
pp. 776-783 ◽  
Author(s):  
T. Rutar ◽  
P. C. Malte
Keyword(s):  
High Pressure ◽  
Nitrous Oxide ◽  
Chemical Reactor ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Sampling Point ◽  
Flame Zone ◽  
Formation Pathway ◽  
Lean Premixed ◽  
Stirred Reactors

Measurements of NOx and CO in methane-fired, lean-premixed, high-pressure jet-stirred reactors (HP-JSRs), independently obtained by two researchers, are well predicted assuming simple chemical reactor models and the GRI 3.0 chemical kinetic mechanism. The single-jet HP-JSR is well modeled for NOx and CO assuming a single PSR for Damko¨hler number below 0.15. Under these conditions, the estimates of flame thickness indicate the flame zone, that is, the region of rapid oxidation and large concentrations of free radicals, fully fills the HP-JSR. For Damko¨hler number above 0.15, that is, for longer residence times, the NOx and CO are well modeled assuming two perfectly stirred reactors (PSRs) in series, representing a small flame zone followed by a large post-flame zone. The multijet HP-JSR is well modeled assuming a large PSR (over 88% of the reactor volume) followed by a short PFR, which accounts for the exit region of the HP-JSR and the short section of exhaust prior to the sampling point. The Damko¨hler number is estimated between 0.01 and 0.03. Our modeling shows the NOx formation pathway contributions. Although all pathways, including Zeldovich (under the influence of super-equilibrium O-atom), nitrous oxide, Fenimore prompt, and NNH, contribute to the total NOx predicted, of special note are the following findings: (1) NOx formed by the nitrous oxide pathway is significant throughout the conditions studied; and (2) NOx formed by the Fenimore prompt pathway is significant when the fuel-air equivalence ratio is greater than about 0.7 (as might occur in a piloted lean-premixed combustor) or when the residence time of the flame zone is very short. The latter effect is a consequence of the short lifetime of the CH radical in flames.

NOx Formation in High-Pressure Jet-Stirred Reactors With Significance to Lean-Premixed Combustion Turbines

2001 ◽  
Author(s):  
Teodora Rutar ◽  
Philip C. Malte
Keyword(s):  
High Pressure ◽  
Nitrous Oxide ◽  
Chemical Reactor ◽  
Sampling Point ◽  
Damkohler Number ◽  
Flame Zone ◽  
Nox Formation ◽  
Damköhler Number ◽  
Lean Premixed ◽  
Stirred Reactors

Measurements of NOx and CO in methane-fired, lean-premixed, high-pressure jet-stirred reactors (HP-JSRs) independently obtained by Rutar [1] and Rutar et al. [2] and by Bengtsson [3] and Bengtsson et al. [4] are well predicted assuming simple chemical reactor models and the GRI 3.0 chemical kinetic mechanism. The single-jet HP-JSR of Rutar [1] and Rutar et al. [2] is well modeled for NOx and CO assuming a single PSR for Damköhler number below 0.15. Under these conditions, the estimates of flame thickness indicate the flame zone, that is, the region of rapid oxidation and large concentrations of free radicals, fully fills the HP-JSR. For Damköhler number above 0.15, that is, for longer residence times, the NOx and CO are well modeled assuming two PSRs in series, representing a small flame zone followed by a large post-flame zone. The multi-jet reactor of Bengtsson [3] and Bengtsson et al. [4] is well modeled assuming a large PSR (over 88% of the reactor volume) followed by a short PFR, which accounts for the exit region of the HP-JSR and the short section of exhaust prior to the sampling point. The Damköhler number is estimated between 0.01 and 0.03. Our modeling shows the NOx formation pathway contributions. Although all pathways, including Zeldovich (under the influence of super-equilibrium O-atom), nitrous oxide, Fenimore prompt, and NNH, contribute to the total NOx predicted, of special note are the following findings: 1) NOx formed by the nitrous oxide pathway is significant throughout the conditions studied; and 2) NOx formed by the Fenimore prompt pathway is significant when the fuel-air equivalence ratio is greater than about 0.7 (as might occur in a piloted lean-premixed combustor) or when the residence time of the flame zone is very short. The latter effect is a consequence of the short lifetime of the CH radical in flames.

Development and Application of an Eight-Step Global Mechanism for CFD and CRN Simulations of Lean-Premixed Combustors

2007 ◽  
Author(s):  
Igor V. Novosselov ◽  
Philip C. Malte
Keyword(s):  
Chemical Reactor ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Lean Premixed Combustion ◽  
Chemical Reactor Network ◽  
Elevated Pressures ◽  
Nitric Oxide Formation ◽  
No Formation ◽  
Lean Premixed ◽  
Reactor Network

In this paper, the development of an eight-step global chemical kinetic mechanism for methane oxidation with nitric oxide formation in lean-premixed combustion at elevated pressures is described and applied. In particular, the mechanism has been developed for use in computational fluid dynamics (CFD) and chemical reactor network (CRN) simulations of combustion in lean-premixed gas turbine engines. Special attention is focused on the ability of the mechanism to predict NOx and CO exhaust emissions. Applications of the eight-step mechanism are reported in the paper, all for high-pressure, lean-premixed, methane-air (or natural gas-air) combustion. The eight steps of the mechanism are as follows: 1. Oxidation of the methane fuel to CO and H2O. 2. Oxidation of the CO to CO2. 3. Dissociation of the CO2 to CO. 4. Flame NO formation by the Zeldovich and nitrous oxide mechanisms. 5. Flame NO formation by the prompt and NNH mechanisms. 6. Post-flame NO formation by equilibrium H-atom attack on equilibrium N2O. 7. Post-flame NO formation by equilibrium O-atom attack on equilibrium N2O. 8. Post-flame Zeldovich NO formation by equilibrium O-atom attack on N2.

Development and Application of an Eight-Step Global Mechanism for CFD and CRN Simulations of Lean-Premixed Combustors

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Igor V. Novosselov ◽  
Philip C. Malte
Keyword(s):  
Chemical Reactor ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Lean Premixed Combustion ◽  
Chemical Reactor Network ◽  
Elevated Pressures ◽  
No Formation ◽  
Lean Premixed ◽  
Network Simulations ◽  
Reactor Network

In this paper, the development of an eight-step global chemical kinetic mechanism for methane oxidation with nitric oxide formation in lean-premixed combustion at elevated pressures is described and applied. In particular, the mechanism has been developed for use in computational fluid dynamics and chemical reactor network simulations of combustion in lean-premixed gas turbine engines. Special attention is focused on the ability of the mechanism to predict NOx and CO exhaust emissions. Applications of the eight-step mechanism are reported in the paper, all for high-pressure, lean-premixed, methane-air (or natural gas-air) combustion. The eight steps of the mechanism are as follows: (1) oxidation of the methane fuel to CO and H2O, (2) oxidation of the CO to CO2, (3) dissociation of the CO2 to CO, (4) flame-NO formation by the Zeldovich and nitrous oxide mechanisms, (5) flame-NO formation by the prompt and NNH mechanisms, (6) postflame-NO formation by equilibrium H-atom attack on equilibrium N2O, (7) postflame-NO formation by equilibrium O-atom attack on equilibrium N2O, and (8) postflame Zeldovich NO formation by equilibrium O-atom attack on N2.

Chemical Reactor Network Application to Emissions Prediction for Industial DLE Gas Turbine

2006 ◽  
Author(s):  
I. V. Novosselov ◽  
P. C. Malte ◽  
S. Yuan ◽  
R. Srinivasan ◽  
J. C. Y. Lee
Keyword(s):  
Gas Turbine ◽  
Chemical Reactor ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Ongoing Research ◽  
Chemical Reactor Network ◽  
Reaction Zones ◽  
Reactor Network

A chemical reactor network (CRN) is developed and applied to a dry low emissions (DLE) industrial gas turbine combustor with the purpose of predicting exhaust emissions. The development of the CRN model is guided by reacting flow computational fluid dynamics (CFD) using the University of Washington (UW) eight-step global mechanism. The network consists of 31 chemical reactor elements representing the different flow and reaction zones of the combustor. The CRN is exercised for full load operating conditions with variable pilot flows ranging from 35% to 200% of the neutral pilot. The NOpilot. The NOx and the CO emissions are predicted using the full GRI 3.0 chemical kinetic mechanism in the CRN. The CRN results closely match the actual engine test rig emissions output. Additional work is ongoing and the results from this ongoing research will be presented in future publications.

scholarly journals Investigating the Effects of Chemical Mechanism on Soot Formation Under High-Pressure Fuel Pyrolysis

2021 ◽  
Vol 7 ◽  
Author(s):  
Nick J. Killingsworth ◽  
Tuan M. Nguyen ◽  
Carter Brown ◽  
Goutham Kukkadapu ◽  
Julien Manin
Keyword(s):  
High Pressure ◽  
Soot Formation ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Chemical Mechanism ◽  
Navier Stokes ◽  
Chemical Mechanisms ◽  
Constant Volume Combustion Chamber ◽  
Fuel Pyrolysis ◽  
Soot Model

We performed Computational Fluid Dynamics (CFD) simulations using a Reynolds-Averaged Navier-Stokes (RANS) turbulence model of high-pressure spray pyrolysis with a detailed chemical kinetic mechanism encompassing pyrolysis of n-dodecane and formation of polycyclic aromatic hydrocarbons. We compare the results using the detailed mechanism and those found using several different reduced chemical mechanisms to experiments carried out in an optically accessible, high-pressure, constant-volume combustion chamber. Three different soot models implemented in the CONVERGE CFD software are used: an empirical soot model, a method of moments, and a discrete sectional method. There is a large variation in the prediction of the soot between different combinations of chemical mechanisms and soot model. Furthermore, the amount of soot produced from all models is substantially less than experimental measurements. All of this indicates that there is still substantial work that needs to be done to arrive at simulations that can be relied on to accurately predict soot formation.

scholarly journals Characterization of NOx, N2O, and CO for Lean-Premixed Combustion in a High-Pressure Jet-Stirred Reactor

1996 ◽  
Author(s):  
Robert C. Steele ◽  
Jon H. Tonouchi ◽  
David G. Nicol ◽  
David C. Horning ◽  
Philip C. Malte ◽  
...  
Keyword(s):  
High Pressure ◽  
Computational Models ◽  
Chemical Reactor ◽  
Reactor Model ◽  
N2o Formation ◽  
Nox Formation ◽  
Lean Premixed Combustion ◽  
Stirred Reactor ◽  
Lean Premixed ◽  
In Series

A high-pressure jet-stirred reactor (HP-JSR) has been built and applied to the study of NOx and N2O formation and CO oxidation in lean-premixed (LPM) combustion. The measurements obtained with the HP-JSR provide information on how NOx forms in lean-premixed, high-intensity combustion, and provide comparison to NOx data published recently for practical LPM combustors. The HP-JSR results indicate that the NOx yield is significantly influenced by the rate of relaxation of super-equilibrium concentrations of the O-atom. Also indicated by the HP-JSR results are characteristic NOx formation rates. Two computational models are used to simulate the HP-JSR, and to provide comparison to the measurements. The first is a chemical reactor model (CRM) consisting of two perfectly-stirred reactors (PSRs) placed in series. The second is a stirred reactor model with finite rate macromixing (i.e., recirculation) and micromixing. The micromixing is treated by either coalescence-dispersion (CD) or interaction-by-exchange-with-the-mean (IEM) theory. Additionally, a model based on one-dimensional gas dynamics with chemical reaction is used to assess chemical conversions within the gas sample probe.

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

1998 ◽  
Vol 120 (2) ◽  
pp. 303-310 ◽  
Author(s):  
R. C. Steele ◽  
J. H. Tonouchi ◽  
D. G. Nicol ◽  
D. C. Horning ◽  
P. C. Malte ◽  
...  
Keyword(s):  
High Pressure ◽  
Computational Models ◽  
Chemical Reactor ◽  
Reactor Model ◽  
N2o Formation ◽  
Nox Formation ◽  
Lean Premixed Combustion ◽  
Stirred Reactor ◽  
Lean Premixed ◽  
In Series

A high-pressure jet-stirred reactor (HP-JSR) has been built and applied to the study of NOx and N2o formation and CO oxidation in lean-Premixed (LPM) combustion. The measurements obtained with the HP-JSR Provide information on how NOx forms in lean-premixed, high-intensity combustion, and provide comparison to NOx data published recently for practical LPM combustors. The HP-JSR results indicate that the NOx yield is significantly influenced by the rate of relaxation of super-equilibrium concentrations of the O-atom. Also indicated by the HP-JSR results are characteristic NOx formation rates. Two computational models are used to simulate the HP-JSR and to provide comparison to the measurements. The first is a chemical reactor model (CRM) consisting of two perfectly stirred reactors (PSRs) placed in series. The second is a stirred reactor model with finite rate macromixing (i.e., recirculation) and micromixing. The micromixing is treated by either coalescence-dispersion (CD) or interaction by exchange with the mean (IEM) theory. Additionally, a model based on one-dimensional gas dynamics with chemical reaction is used to assess chemical conversions within the gas sample probe.

Numerical Simulation of Pollutant Emissions in a Can-Type Low NOx Gas Turbine Combustor

2010 ◽  
Author(s):  
Di Wang ◽  
Wenjun Kong ◽  
Yuhua Ai ◽  
Baorui Wang
Keyword(s):  
Gas Turbine ◽  
Plug Flow ◽  
Combustion Process ◽  
Chemical Reactor ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Pollutant Emissions ◽  
Inlet Temperature ◽  
Gas Turbine Combustor ◽  
In Series

A research program is in development in China in order to realize a demonstrator of combined cooling heating and power system (CCHP) with net electrical output around 100kW by using of a can-type micro gas turbine. In this paper, numerical simulations were completed to investigate the pollutant emissions in a can-type low NOx gas turbine combustor. Based on the analysis of the computational fluid dynamics (CFD) results, a Chemical Reactor Network (CRN) model was set up to simulate the pollutant emissions in the combustor with detailed gas-phase chemical kinetic mechanism of GRI-Mech 3.0. The CRN consists of a number of ideal reactors of the perfectly stirred reactors (PSR) and plug flow reactors (PFR) in series and parallel structures. Two types of CRN models were designed. One is relatively simple, another is more complex. The results show that the complex CRN model corresponds with the actual combustion process better. The trends of nitrogen oxides (NOx) and carbon monoxide (CO) varying with the equivalence ratio were conducted. Effects of the inlet temperature and pressure on NOx and CO emissions were also presented in this paper. At last, the numerical results are compared with the experimental results.

Derivation of a global chemical kinetic mechanism for methane ignition and combustion

1994 ◽  
Vol 91 ◽  
pp. 365-382 ◽  
Author(s):  
J Revel ◽  
JC Boettner ◽  
M Cathonnet ◽  
JS Bachman
Keyword(s):  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Chemical Kinetic Mechanism ◽  
Ignition And Combustion
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