Similar articles

Abstract: This paper presents an experimental study on the emission characteristics and combustion instabilities of oxy-fuel combustions in a swirl-stabilized combustor. Different oxygen concentrations (X_oxy=25%~45%, where X_oxy is oxygen concentration by volume), equivalence ratios (φ=0.75~1.15) and combustion powers (CP=1.08~2.02 kW) were investigated in the oxy-fuel (CH₄/CO₂/O₂) combustions, and reference cases (X_oxy=25%~35%, CH₄/N₂/O₂ flames) were covered. The results show that the oxygen concentration in the oxidant stream significantly affects the combustion delay in the oxy-fuel flames, and the equivalence ratio has a slight effect, whereas the combustion power shows no impact. The temperature levels of the oxy-fuel flames inside the combustion chamber are much higher (up to 38.7%) than those of the reference cases. Carbon monoxide was vastly produced when X_oxy>35% or φ>0.95 in the oxy-fuel flames, while no nitric oxide was found in the exhaust gases because no N₂ participates in the combustion process. The combustion instability of the oxy-fuel combustion is very different from those of the reference cases with similar oxygen content. oxy-fuel combustions excite strong oscillations in all cases studied X_oxy=25%~45%. However, no pressure fluctuations were detected in the reference cases when X_oxy>28.6% accomplished by heavily sooting flames which were not found in the oxy-fuel combustions. Spectrum analysis shows that the frequency of dynamic pressure oscillations exhibits randomness in the range of 50~250 Hz, therefore resulting in a very small resultant amplitude. Temporal oscillations are very strong with amplitudes larger than 200 Pa, even short time fast Fourier transform (FFT) analysis (0.08 s) shows that the pressure amplitude can be larger than 40 Pa.

[1] Andersson, K., Johnsson, F., 2007. Flame and radiation characteristics of gas-fired O₂/CO₂ combustion. Fuel, 86(5-6):656-668.

[2] Bolland, O., Mathieu, P., 1998. Comparison of two CO₂ removal options in combined cycle power plants. Energy Conversion and Management, 39(16-18):1653-1663.

[3] Boushaki, T., Sautet, J.C., Salentey, L., Labegorre, B., 2007. The behavior of lifted oxy-fuel flames in burners with separated jets. International Communications in Heat and Mass Transfer, 34(1):8-18.

[4] Brookes, S.J., Moss, J.B., 1999. Measurements of soot production and thermal radiation from confined turbulent jet diffusion flames of methane. Combustion and Flame, 116(1-2):49-61.

[5] Ditaranto, M., Hals, J., 2006. Combustion instabilities in sudden expansion oxy-fuel flames. Combustion and Flame, 146(3):493-512.

[6] Dowling, A.P., 2000. The Challenges of Lean Premixed Combustion. Proceeding of the International Gas Turbine Congress, Tokyo.

[7] Giezendanner, R., Weigand, P., Duan, X.R., Meier, W., Meier, U., Aigner, M., Lehmann, B., 2005. Laser-based investigations of periodic combustion instabilities in a gas turbine model combustor. Journal of Engineering for Gas Turbines and Power, 127(3):492-496.

[8] Hobson, D.E., Fackrell, J.E., Hewitt, G., 2000. Combustion instabilities in industrial gas turbines-measurements on operating plant and thermoacoustic modeling. Journal of Engineering for Gas Turbines and Power, 122(3):420-428.

[9] Johnson, M.R., Littlejohn, D., Nazeer, W.A., Smith, K.O., Cheng, R.K., 2005. A comparison of the flowfields and emissions of high-swirl injectors and low-swirl injectors for lean premixed gas turbines. Proceedings of the Combustion Institute, 30(2):2867-2874.

[10] Keller, J.J., 1995. Thermoacoustic oscillations in combustion chambers of gas turbines. AIAA Journal, 33(12):2280-2287.

[11] Kim, H.K., Kim, Y., Lee, S.M., Ahn, K.Y., 2006. Emission characteristics of the 0.03 MW oxy-fuel combustor. Energy & Fuel, 20(5):2125-2130.

[12] Kim, H.K., Kim, Y., Lee, S.M., Ahn, K.Y., 2007a. Studies on combustion characteristics and flame length of turbulent oxy-fuel flames. Energy & Fuel, 21(3):1459-1467.

[13] Kim, H.K., Kim, Y., Lee, S.M., Ahn, K.Y., 2007b. NO reduction in 0.03-0.2 MW oxy-fuel combustor using flue gas recirculation technology. Proceedings of the Combustion Institute, 31(2):3377-3384.

[14] Li, G.N., Zhou, H., Cen, K.F., 2007. Experimental Study of Thermoacoustic Instability under Different Swirl Intensities. Challenges Power Engineering and Environment, Zhejiang University Press & Springer, Hangzhou, p.670-676.

[15] Li, H., Zhou, X., Jeffries, J.B., Hanson, R.K., 2007. Sensing and control of combustion instabilities in swirl-stabilized combustors using Diode-laser absorption. AIAA Journal, 45(2):390-398.

[16] Lyngfelt, A., Leckner, B., Mattisson, T., 2001. A fluidized-bed combustion process with inherent CO₂ separation: application of chemical-looping combustion. Chemical Engineering Science, 56(10):3101-3113.

[17] Masri, A.R., Kalt, P.A., Barlow, R.S., 2004. The compositional structure of swirl-stabilized turbulent nonpremixed flames. Combustion and Flame, 137(1-2):1-37.

[18] Meier, W., Weigand, P., Duan, X.R., Giezendanner-Thoben, R., 2007. Detailed characterization of the dynamics of thermoacoustic pulsations in a lean premixed swirl flames. Combustion and Flame, 150(1-2):2-26.

[19] Naik, S.V., Laurendeau, N.M., Cooke, J.A., Smooke, M.D., 2003. Effect of radiation on nitric oxide concentration under sooting oxy-fuel conditions. Combustion and Flame, 134(4):425-431.

[20] Qian, S., Chen, D., 1999. Joint time frequency analysis. IEEE Signal Processing Magazine, 16(2):52-67.

[21] Saito, M., Sato, M., Nishimura, A., 1998. Soot suppression by acoustic oscillated combustion. Fuel, 77(9-10):973-978.

[22] Syred, N., 2006. A review of oscillation mechanisms and the role of the processing vortex core (PVC) in swirl combustion systems. Progress in Energy and Combustion Science, 32(2):93-161.