Oxy-Fuel Burner Characterization: From Laboratory to Industry

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Imaging experiments were made on both the 30 kW lab scale and 340 kW industrial scale VM burner. For these experiments a modified (removal ofall UV absorbing glass components) commercial video camera was used. This camera is small and inexpensive making it well suited for use in the field. Spectrally selective images were obtained by using narrowband filters at the wavelengths of interest, e.g., 308 run (OR), 432 nm (CH), 516 nm (C2) and filters for background [4]. To insure that the images collected are representative of the radical species and not of the background or soot emission, a comparison of the image profiles to single-point emission spectra measurements using a conventional monochromator and collection optic system was performed. Monitoring the OH emission provides qualitative information on the location of the reaction zone between fuel and O2. In regions where the emission intensity is strong is an approximate indication of high heat release due to the fast reaction between fuel and O2. Also, an OH image showing large areas of strong emission would indicate a higher temperature flame compared to an image showing small areas of OH emission. Thus OH images with large areas of emission result in a higher NOx producing flame due to the thermal Zeldovich reaction mechanism [3]. However the production of CO would decrease since the main path for CO destruction is CO+OH->C02+H [3]. Examples of OH emission obtained for 50-averaged images with background subtracted from a 30 kW VM burner are shown in Figures 2 and 3. The images obtained reveal a number of characteristics for the different operating conditions. Figure 2 shows the OH emission signal for a 30 kW VM burner with no O2 in the inner tube. The intensity of the OH emission is clearly seen along the interface between the fuel and O2. For the case with 40% O2 injected in the inner tube, the distribution of OH is significantly different as shown in Figure 3. In this case two distinct interfaces are observed one between the outer O2 and fuel with the other resulting from the inner O2 and fuel. These strongly emitting zones indicate the fast reactions occuring between O2 and fuel. 3.2 Numerical Simulation To explain the trend in the visible flame length for changes in the inner O2 flowrate numerical simulations were conducted for an industrial 500 kW scale VM burner. For the model an 7