Thermal and chemical characteristics of the flames obtained from an industrial size regenerative combustion furnace have been obtained spectroscopically. The combustion characteristics of diffusion or premixed flames in the regenerative high-temperature air combustion facility have been examined using coal gas as the fuel. The fuel gas composition consisted of $H2,$ hydrocarbon, CO, and $N2.$ Monochromatic images of the flames have been observed in the emission mode using a CCD camera fitted with an optical band pass filter at the desired wavelength. The two-dimensional temperature distribution in the furnace has been determined using the two-line method by utilizing the Swan emission bands from within the flame. The emission intensity profiles of NO, as well as OH and CH radicals have also been observed spectroscopically. The results showed quite uniform two-dimensional temperature distribution and emission intensity of OH and CH radical species for the diffusion flame case as compared to the premixed case using high-temperature combustion air. The premixed flame case showed high local values and large fluctuations in the combustion zone for both emission intensity and temperature distribution. The temperature distribution of soot particles in the premixed flame was also determined using the two-color optical method. The results showed high local value of temperature, similar to that found for the gas temperature using signatures for $C2$ species at two different wavelengths. In contrast the distribution of temperature for soot particles was different. The location of the maximum soot temperature shifted to downstream positions of the flame as compared to the maximum gas temperature regions measured from the $C2$ species. The experimental results are discussed in conjunction with those obtained from the heat simulation analyses.

1.
Tsuji, H., Gupta, A. K., Hasegawa, T., Katsuki, M., Kishimoto, K., and Morita, M., 2003, High Temperature Air Combustion: From Energy Conservation to Pollution Reduction, CRC Press, Boca Raton, FL.
2.
Ishiguro, T., and Tsuge, S., Furuhata, T., Kitagawa, K., Arai, N., Hasegawa, T., Tanaka, R., and Gupta, A. K., 1998, “Homogenization and Stabilization During Combustion of Hydrocarbons With Preheated Air,” Proc. Twenty-Seventh Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, PA, pp. 3205–3213.
3.
Katsuki, M., and Hasegawa, T., 1998, “The Science and Technology of Combustion in Highly Preheated Air,” 27th Symposium (Intl.) on Combustion, The Combustion Institute, Pittsburgh, PA, pp. 3135–3146.
4.
Gupta, A. K., 2001, “High Temperature Air Combustion: Experiences from the USA-Japan Joint Energy Project,” Invited Keynote Lecture at the 4th High Temperature Air Combustion and Gasification Symposium, Rome, Italy, Nov. 27–30.
5.
Hasegawa
,
T.
,
Mochida
,
S.
, and
Gupta
,
A. K.
,
2002
, “
Development of Advanced Industrial Furnace Using Highly Preheated Air Combustion
,”
J. Propul. Power
,
18
(
2
), pp.
233
239
.
6.
Ishii, T., Zhang, C., and Sugiyama, S., 1997, “Numerical Analysis of NOx formation Rate in a Regenerative Furnace,” Proceedings of the ASME International Joint Power Generation Conference (IJPGC97), ASME, New York, pp. 267–278.
7.
Zhang
,
C.
,
Ishii
,
T.
,
Hino
,
Y.
, and
Sugiyama
,
S.
,
2000
, “
The Numerical and Experimental Study of Non-Premixed Combustion Flames in Regenerative Furnace
,”
ASME J. Heat Transfer
,
122
, pp.
287
293
.
8.
Gupta
,
A. K.
,
Bolz
,
S.
, and
Hasegawa
,
T.
,
1999
, “
Effect of Air Preheat and Oxygen Concentration on Flame Structure and Emission
,”
ASME J. Energy Resour. Technol.
,
121
, pp.
209
216
.
9.
Gupta, A. K., and Li, Z., 1997, “Effect of Fuel Property on the Structure of Highly Preheated Air Flames,” Proc. Intl. Joint Power Generation Conference (IJPGC), ASME, New York, ASME EC-Vol. 5, pp. 247–258.
10.
Konishi
,
N.
,
Kitagawa
,
K.
,
Arai
,
N.
, and
Gupta
,
A. K.
,
2002
, “
Two-Dimensional Spectroscopic Analysis of Spontaneous Emission From a Flame Using Highly Preheated Air Combustion
,”
J. Propul. Power
,
18
, pp.
199
204
.
11.
Tien, C. L., 1968, Thermal Radiation Properties of Gases (Advances in Heat Transfer, Vol. 5), Academic Press, New York, pp. 253–324.
12.
Heitler, W., 1954, The Quantum Theory of Radiation, Oxford University Press, New York, pp. 136–174.
13.
Sarofim, A. F., and Hottel, H. C., 1978, “Radiative Transfer in Combustion Chambers: Influence of Alternative Fuels,” Proceedings of the Sixth International Heat Transfer Conference, Hemisphere, Washington, DC, 6, pp. 199–217.
14.
Foster
,
P. J.
, and
Howarth
,
C. R.
,
1968
, “
Optical Constants of Carbons and Coals in the Infrared
,”
Carbon
,
6
, pp.
719
729
.
15.
Millikan
,
R. C.
,
1961
, “
Optical Properties of Soot
,”
J. Opt. Soc. Am.
,
51
, pp.
698
699
.
16.
Millikan, R. C., 1961, “Sizes, Optical Properties and Temperatures of Soot Particles,” The Fourth Symposium on Temperature, Its Measurement and Control in Science and Industry, 3, pp. 497–507.
17.
Weber, R., 1996, “Scaling Characteristics of Aerodynamics, Heat Transfer and Pollutant Emission in Industrial Flames,” Proceedings of the 26th Symposium International on Combustion, The Combustion Institute, Pittsburgh, PA, pp. 3343–3354.
18.
Johnson
,
R. C.
,
1927
, “
The Structure and Origin of the Swan Band Spectrum of Carbon
,”
Philos. Trans. R. Soc. London, Ser. A
,
226
, pp.
157
231
.