NO x formation pathways in lean-premixed-prevapourized combustion of fuels with carbon-to-hydrogen ratio between 0.25 and 0.88

Abstract

NO _x measurements in jet-stirred reactor (JSR) combustion of seven fuels are modelled using three complete chemical kinetic mechanisms. The two JSRs are operated at 1790 K, 1 atm, 2–4 ms, and the fuel-air equivalence ratio of 0.61. The modelled fuels are methanol, methane, ethane, ethene, propane, n-butane, and toluene. The experimental database also includes C1-C4 alkane mixtures, two light naphtas, four number two diesel oils, and benzene. The fuels and air are premixed, prevapourized, and preheated with a temperature-staged prevapourizer-premixer and an air-heater. Experiments show NO _x and CO increase when burning fuels with increasing carbon-to-hydrogen ratio (from 0.25 to 0.88). The data are analysed using three complete chemical kinetic mechanisms: GRI 3.0 Mech., CNRS' C1-C4 hydrocarbon oxidation mechanism, and CNRS' toluene oxidation mechanism. The modelling shows that the increase in NO _x with the fuel carbon-to-hydrogen ratio is because of the increase in the NO formation via NNH, Zeldovich, and nitrous oxide pathways. The NNH pathway produces between 25 and 45 per cent of the NO formed. GRI 3.0 Mech. tends to favour this pathway since it forms more O, H, and NNH reactive species than the CNRS' C1-C4 hydrocarbon mechanism. Several rate constants for NNH + O → NH + NO are considered and best agreement using two and three perfectly stirred reactor schemes is found with the rate constant k = 7 × 10¹³ cm³/mol/s.

Keywords

formation pathways stirred reactors chemical reactor modelling methanol alkanes ethene toluene paraffin

Get full access to this article

View all access options for this article.

References

Steele

R. C.

Tonouchi

J. H.

Nicol

D. G.

Horning

D. C.

Malte

P. C.

Pratt

D. T.

Characterization of NO _x , N₂O, and CO for lean-premixed combustion in a high-pressure jet-stirred reactor. Trans. ASME, J. Eng. Gas Turb. Power, 1998, 120, pp. 303–310.

Leonard

Stegmaier

Development of an aeroderivative gas turbine dry low emissions combustion system. ASME paper 93-GT-288, 1993 (ASME, New York).

Joshi

N. D.

Epstein

M. J.

Durlak

Marakovits

Sabla

P. E.

Development of a fuel air premixer for aero-derivative dry low emissions combustors. ASME paper 94-GT-253, 1994 (ASME, New York).

Turns

S. R.

An introduction to combustion, 2nd edititon, 2000, p. 460 (McGraw-Hill Inc., New York, NY).

Abraham

Williams

F. A.

Bracco

F. V.

A discussion of turbulent flame structure in premixed charges. Proceedings of Social Automatic Engineering, Engine Combustion Analysis: New Approaches, P-156, 1985, pp. 27–42.

Rutar

Malte

P. C.

Kramlich

J. C.

Investigation of NO _x and CO formation in lean-premixed, methane-air, high-intensity, confined flames at elevated pressures. Proc. Combust. Inst., 2000, 28, 2435–2441.

Rutar

Malte

P. C.

NO _x formation in high-pressure jet-stirred reactors with significance to leanpremixed combustion turbines. J. Eng. Gas Turb. Power, 2002, 124 (4), 776–783.

Lee

J. C. Y.

Malte

P. C.

Benjamin

M. A.

Low NO _x combustion for liquid fuels: atmospheric pressure experiments using a staged prevaporizer-premixer. J. Eng. Gas Turb. Power, 2003, 125 (4), 761–771.

Lee

J. C. Y.

Reduction of NO _x emission for lean prevapourized-premixed combustors. PhD Thesis, University of Washington, Seattle, WA, 2000.

10.

Lee

A. C.

Experimental investigation of liquid fuel vaporization and mixing in steam and air. MS Thesis, University of Washington, Seattle, WA, 2003.

11.

Davis

S. G.

Wang

Brezinsky

Law

C. K.

Laminar flame speeds and oxidation kinetics of benzene-air and toluene-air flames. Proc. Combust. Inst, 1996, 26, 1025–1033.

12.

Muller

U. C.

Bollig

Peters

Approximations for burning velocities and Markstein numbers for lean hydrocarbon and methanol flames. Combust. Flame, 1997, 108, 349–356.

13.

Chomiak

Combustion: a study in theory, fact and application, 1990, p. 73 (Gordon and Breach Science Publishers, New York).

14.

Schmid

H.-P.

Habisreuther

Leuckel

A model for calculating heat release in premixed turbulent flames. Comb. Flame, 1998, 113, 79–91.

15.

Bray

K. N. C.

Turbulent flows with premixed reactants. In Turbulent reacting flows (Eds Libby

P. A.

Williams

F. A.

), 1980, pp. 115–183 (Springer-Verlag, New York).

16.

Smith

G. P.

Golden

D. M.

Frenklach

Moriarty

N. W.

Eiteneer

Goldenberg

Bowman

C. T.

Hanson

Song

Gardiner

W. C.

Jr. Lissianski

Qin

GRI-Mech. 3.0. Available from http://www.me.berkeley.edu/gri_mech/, 2006.

17.

Dagaut

Luche

Cathonnet

Experimental and kinetic modeling of the reduction of NO by propene at 1 atm. Combust. Flame, 2000, 121, 651–661.

18.

Dagaut

Pengloan

Ristori

Oxidation, ignition and combustion of tolune: Experimental and detailed chemical kinetic modeling. Phys. Chem. Chem. Phys, 2002, 4, 1846–1854.

19.

Bengtsson

K. U. M.

Benz

Schaeren

Frouzakis

C. E.

NyO _x formation in lean premixed combustion of methane in a high-pressure jet-stirred reactor. Proc. Combust. Inst., 1998, 27, 1393–1401.

20.

Steele

R. C.

NO _x and N₂O formation in lean-premixed jet-stirred reactors operated from 1 to 7 atm. PhD Thesis, University of Washington, Seattle, WA, 1995.

21.

Novosselov

I. V.

Chemical reactor networks for combustion systems modeling. PhD Thesis, University of Washington, Seattle, WA, 2006.

22.

Nicol

D. G.

Malte

P. C.

Steele

R. C.

Simplified models for NO _x production rates in lean-premixed combustion. ASME paper 94-GT-432, 1994 (ASME, New York).

23.

Haworth

N. L.

Mackie

J. C.

Bacskay

G. B.

An ab initio quantum chemical and kinetic study of the NNH + O reaction potential energy surface: how important is this route to NO in combustion?

J. Phys. Chem. A, 2003, 107, 6792–6803.

24.

Konnov

A. A.

De Ruyck

Temperature-dependent rate constant for the reaction NNH + O + NH + NO. Comb. Flame, 2001, 125, 1258–1264.