scholarly journals Experimental and Numerical Studies of Two-Stage Ethane-Air Flames

1999 ◽  
Author(s):  
M. M. Y. Waly ◽  
S. C. Li ◽  
F. A. Williams
Keyword(s):  
Chemical Kinetic ◽  
Two Stage ◽  
Nox Formation ◽  
Pollutant Formation ◽  
Numerical Studies ◽  
Numerical Predictions ◽  
Air Stream ◽  
Stage Combustion ◽  
Reduce Emissions ◽  
Flame Chemistry

This paper reports results of experimental and numerical investigations on ethane-air two-stage combustion in a counterflow burner where the fuel stream, which is partially premixed with air for equivalence ratios from 1.6 to 3.0, flows against a pure air stream. Similar to methane, the two-stage ethane combustion exhibits a green fuel-rich premixed flame and a blue diffusion flame. Flame structures, including concentration profiles of stable intermediate species such as C2H4, C2H2 and CH4, are measured by a gas chromatography and are calculated by numerical integrations of the conservation equations employing an updated elementary chemical-kinetic data base. The implications of the results from these experimental measurements and numerical predictions are summarized, the flame chemistry of ethane two-stage combustion at different degrees of premixing (or equivalence ratio) is discussed, and the relationship between NOx formation and the degree of premixing is established. The present work helps to increase understanding of flame chemistry of hydrocarbon fuels, identify important reactions for pollutant formation and suggest means to reduce emissions.

Experimental and Numerical Studies of Two-Stage Ethane-Air Flames

2000 ◽  
Vol 122 (4) ◽  
pp. 651-658 ◽  
Author(s):  
M. M. Y. Waly ◽  
S. C. Li ◽  
F. A. Williams
Keyword(s):  
Chemical Kinetic ◽  
Two Stage ◽  
Nox Formation ◽  
Pollutant Formation ◽  
Numerical Studies ◽  
Numerical Predictions ◽  
Air Stream ◽  
Stage Combustion ◽  
Reduce Emissions ◽  
Flame Chemistry

This paper reports results of experimental and numerical investigations on ethane-air two-stage combustion in a counterflow burner where the fuel stream, which is partially premixed with air for equivalence ratios from 1.6 to 3.0, flows against a pure air stream. Similar to methane, the two-stage ethane combustion exhibits a green fuel-rich premixed flame and a blue diffusion flame. Flame structures, including concentration profiles of stable intermediate species such as C2H4,C2H2 and CH4, are measured by a gas chromatography and are calculated by numerical integrations of the conservation equations employing an updated elementary chemical-kinetic data base. The implications of the results from these experimental measurements and numerical predictions are summarized, the flame chemistry of ethane two-stage combustion at different degrees of premixing (or equivalence ratio) is discussed, and the relationship between NOx formation and the degree of premixing is established. The present work helps to increase understanding of flame chemistry of hydrocarbon fuels, identify important reactions for pollutant formation and suggest means to reduce emissions. [S0742-4795(00)01303-X]

Experimental and Numerical Studies of NOx Formation in Two-Stage Methane-Air Flames

1998 ◽  
Author(s):  
S. C. Li ◽  
F. A. Williams
Keyword(s):  
Gas Turbines ◽  
Chemical Kinetic ◽  
Low Flow ◽  
Sampling System ◽  
Two Stage ◽  
Nox Formation ◽  
Reaction Rate Constants ◽  
Numerical Integrations ◽  
Air Stream ◽  
Reduce Emissions

To help understand how staged combustion aids in reducing emissions of oxide of nitrogen from gas turbines, measurements and computations are made of structures of two-stage counterflow methane-air flames at nomal atmospheric pressure and a feed-stream temperature of about 300 K. The fuel stream is partially premixed, with equivalence ratios from 1.5 to 3.0. To the air stream is added up to 10% by mass of water spray, carbon dioxide, or nitrogen. Flame structures, including formation of species containing two carbon atoms, are measured by gas chromatography of samples withdrawn by fine quartz probes and are calculated by numerical integrations of the conservation equations employing an updated elementary chemical-kinetic data base. The same sampling system is employed with a low-flow-rate NOx analyzer to obtain profiles of nitric oxide and nitrogen dioxide, which are also calculated in the numerical integrations. The two-stage flame exhibits a green fuel-rich premixed flame and a blue diffusion flame with the maximum NOx concentrations found near the blue flame. At an air-side strain rate of 50 s−1, for fuel-side equivalence ratios of 1.5, 2.0, 2.5 and 3.0, respectively, measured peak NOx concentrations were about 70, 90, 100 and 90 ppm, reduced to 60, 70, 50, and 40 ppm, respectively, when 5% water by mass was added to the air stream. Results of the numerical integrations were in reasonable agreement with these experimental results when suitable selections were made of certain critical elementary reaction-rate constants. These new NOx measurements and computations help to increase understanding of influences of staging and diluent addition, identify important reactions for pollutant formation and suggest means to reduce emissions.

Reduction of NOx Formation by Water Sprays in Strained Two-Stage Flames

1997 ◽  
Vol 119 (4) ◽  
pp. 836-843 ◽  
Author(s):  
S. C. Li ◽  
N. Ilincic ◽  
F. A. Williams
Keyword(s):  
Diffusion Flames ◽  
Laser Sheet ◽  
Flame Structure ◽  
Flame Temperature ◽  
Temperature Fields ◽  
Two Stage ◽  
Two Phase ◽  
Nox Formation ◽  
Numerical Predictions ◽  
Water Sprays

Staged combustion can be employed to reduce the formation of CO and NOx, stabilize the flame, decrease the flame temperature, and create better working conditions in gas turbine combustors. To help understand influences of partial premixing and addition of water on NOx formation, we study two-stage flames in a counterflow spray burner. This paper reports experimental and theoretical results concerning two-stage combustion in which one feed stream is composed of a fuel-rich mixture of methane and air and the other is air. Water sprays are added to the air stream. This two-phase laminar counterflow configuration exhibits a green premixed flame, a blue diffusion flame, and a vaporization plane. All three are flat and parallel. The separation distances between them decrease with increasing equivalence ratio and strain rate. Flow visualization is provided through illumination by an argon ion laser sheet, velocity fields and spray structure are measured by a phase-doppler particle analyzer, concentration fields of major stable species are measured by gas chromatography of samples withdrawn from the flame, and temperature fields are measured by a thermocouple. Numerical integrations that employ a recent chemical-kinetic data base are performed to model the flame structure and NOx formation. Comparisons of experimental results with numerical predictions are made to test agreement. This work provides information on hydrocarbon combustion in both premixed flames and diffusion flames, indicates how NOx is formed in fuel-rich flames, and suggests how the pollutants can be reduced.

scholarly journals Reduction of NOx Formation by Water Sprays in Strained Two-Stage Flames

1996 ◽  
Author(s):  
S. C. Li ◽  
N. Ilincic ◽  
F. A. Williams
Keyword(s):  
Diffusion Flames ◽  
Laser Sheet ◽  
Flame Structure ◽  
Flame Temperature ◽  
Temperature Fields ◽  
Two Stage ◽  
Two Phase ◽  
Nox Formation ◽  
Numerical Predictions ◽  
Water Sprays

Staged combustion can be employed to reduce the formation of CO and NOx, stabilize the flame, decrease the flame temperature and create better working conditions in gas turbine combustors. To help understand influences of partial premixing and addition of water on NOx formation, we study two-stage flames in a counterflow spray burner. This paper reports experimental and theoretical results concerning two-stage combustion in which one feed stream is composed of a fuel-rich mixture of methane and air and the other is air. Water sprays are added to the air stream. This two-phase laminar counterflow configuration exhibits a green premixed flame, a blue diffusion flame and a vaporization plane. All three are flat and parallel. The separation distances between them decrease with increasing equivalence ratio and strain rate. Flow visualization is provided through illumination by an argon ion laser sheet, velocity fields and spray structure are measured by a phase-doppler particle analyzer, concentration fields of major stable species are measured by gas chromatography of samples withdrawn from the flame, and temperature fields are measured by a thermocouple. Numerical integrations which employ a recent chemical-kinetic data base are performed to model the flame structure and NOx formation. Comparisons of experimental results with numerical predictions are made to test agreement. This work provides information on hydrocarbon combustion in both premixed flames and diffusion flames, indicates how NOx is formed in fuel-rich flames and suggests how the pollutants can be reduced.

Staged Premix EV Combustion in Alstom’s GT24 Gas Turbine Engine

2012 ◽  
Author(s):  
Daniel Guyot ◽  
Thiemo Meeuwissen ◽  
Dieter Rebhan
Keyword(s):  
Gas Turbine ◽  
Distribution System ◽  
Fuel Oil ◽  
Operational Flexibility ◽  
Nox Formation ◽  
Diffusion Type ◽  
Fuel Gas ◽  
Start Up ◽  
Reduce Emissions ◽  
Ev Burner

Reducing gas turbine emissions and increasing their operational flexibility are key targets in today’s gas turbine market. In order to further reduce emissions and increase the operational flexibility of its GT24, Alstom has introduced an internally staged premix system into the GT24’s EV combustor. This system features a rich premix mode for GT start-up and a lean premix mode for GT loading and baseload operation. The fuel gas is injected through two premix stages, one injecting fuel into the burner air slots and one injecting fuel into the centre of the burner cone. Both premix stages are in continuous operation throughout the entire operating range, i.e. from ignition to baseload, thus eliminating the previously used pilot operation during start-up with its diffusion-type flame and high levels of NOx formation. The staged EV combustion concept is today a standard on the current GT26 and GT24. The EV burners of the GT26 are identical to the GT24 and fully retrofittable into existing GT24 engines. Furthermore, engines operating only on fuel gas (i.e. no fuel oil operation) no longer require a nitrogen purge and blocking air system so that this system can be disconnected from the GT. Only minor changes to the existing GT24 EV combustor and fuel distribution system are required. This paper presents validation results for the staged EV burner obtained in a single burner test rig at full engine pressure, and in a GT24 field engine, which had been upgraded with the staged EV burner technology in order to reduce emissions and extend the combustor’s operational behavior.

Two-stage combustion of an ultradispersed aluminum powder in air

1990 ◽  
Vol 26 (2) ◽  
pp. 190-192 ◽  
Author(s):  
A. P. Il'in ◽  
L. T. Proskurovskaya
Keyword(s):  
Aluminum Powder ◽  
Two Stage ◽  
Stage Combustion
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