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Show measuring points along the furnace hearth as shown in Fig. 3. The measurements were conducted when the furnace temperature reached 1673 K, which was measured with a sheathed type-R thermocouple inserted into the furnace. Fuel gas flow rate was maintained at 22.8 m3jh and oxygen flow rate at 55.0 m3/h with an excess air ratio of 1.05. This gave a total thermal input of 265 kW(LHV). RESULTS OF COMBUSTION TEST Effect of gas and oxygen velocity on total radiative flux Figure 5 shows the effect of gas and oxygen velocity on total radiative heat flux for flames A-E. Gas and oxygen velocity was widely varied from 6 to 130 m/s. Lower velocity resulted in higher total radiative heat flux. Flame E, with the lowest velocity of 6 mis, showed the highest total radiative flux. Substantial differences in total radiative heat flux between the flames were observed, with a maximum difference of up to 50% near the burner. Luminous flames were observed when the velocity was low. Inferior flame stability was also observed with lower velocity. Occasionally flame E was observed to bend towards the furnace ceiling due to buoyancy, thereby causing damage to the furnace. To improve flame stability, flames F-I, which had relatively low momentum, were tested with various center gas velocities from 6-32 m/s and low oxygen velocity was maintained at 3-4 m/s. Figure 6 shows the effect of gas velocity or momentum on total radiative heat flux. Lower gas velocity also resulted in higher total radiative flux. Flame F, with the lowest gas and oxygen velocity, resulted in the highest total radative flux. Flame F showed higher heat flux compared to flame E. Flame stability appeared to improve compared with flames A-E. To investigate the effect of nozzle configuration on total radiative flux, the experiments applied flames J-M, in which the injection of gas and oxygen was reversed. Oxygen was injected through the center nozzle and its |