1992 Volume 78 Issue 3 Pages 367-374
High efficiency of heat transfer has been obtained in a smelting reduction furnace which has an essential feature of a thick layer of slag coexisting with carbonaceous materials, when stirring intensity by bottom bubbling is higher than 2 kW/t-metal.
Heat transfer mechanism in this process has been examined both theoretically and experimentally.
(1) Heat transfer by radiation and gas convection was calculated by using a mathematical model and was compared with actual data. This model was constructed by dividing the furnace into three regions depending on the modes of reaction and heat transfer and by taking the mass and heat balances over each region. When the gas temperature is as high as 2170°C, the actual heat transfer can be explained mainly by radiation. But, under practical conditions (gas temperature≤1765°C), the contribution of radiation and gas convection to heat transfer is only 20-30%.
(2) In order to explain the heat transfer when the temperature of exhaust gas was relatively low, the heat transfer by circulation of super-heated carbonaceous material was assumed. The assumption coincides with other data on the reducing reaction and on the combustion in the smelting reduction.