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Show 3. Adjust the angle of the coal feeder nozzle to be more downward if possible. In addition to the change(s) to be made to the coal, the amount of air flow below the coal feeder must be adjusted to the point that stoichiometric combustion can take place near the floor so that the maximum temperature can be reached there. (B) Estimate the Surface Temperature of the Refractory The operating temperature of the refractory (B & W-Phos 93) recommended by the manufacturer is 3000°F. The slag temperature of 3000°F is certainly safe to the refractory. However, because of heat transfer, it is not necessary that the surface temperature of the refractory is above 2849°F which is the melting point of Fe 0 . To make certain that the surface temperature is high enough to keep the slag under a molten state, an estimation is made to determine the upper surface temperature of the refractory. Conditions assumed for the estimation are: The surface temperature of the slag is 3000°F The temperature of the refractory on the bottom surface is 300°F The thickness of the slag is 0.5 in. The thickness of the refractory is 1.5 in. The thermal conductivity of the slag is 17 BTU/hr-ft-°F The thermal conductivity of the refractory is 9 BTU-in/hr-ft2-°F (given by the manufacturer). It is found that the temperature of the refractory on the upper surface is 2961°F which is certainly satisfactory. IV. INSTRUMENTATION FOR THE DETECTION OF IRON ACCUMULATION Because two different approaches are discussed in Section III, instruments used to detect the possibility of iron accumulation are different. The first approach depends on the oxygen content in the furnace so that the detection of gas composition is essential. On the other hand, the second approach depends entirely on the slag temperature so that the temperature must be measured. In general, the detection of iron accumulation is always important. Therefore it is also included in the following: (A) Detection of Gas Composition 6 |