| 摘要 |
PURPOSE:To save electric power considerably by fully operating a base fan in a heating period and a natural cooling period and decreasing the number of revolutions of the base fan within the range of not lowering the overall heat transfer coefft. in a furnace in a soaking period and a force cooling period. CONSTITUTION:The quantity of heat transfer from a furnace to the center of a coil in a heating period and a soaking period is as per the equation I, wherein (t) is the temp. of an inner cover, t4 is the temp. at the center of the coil, Fc is the heat transfer area of the coil, beta Fi/Fc, Fi are the heat transfer areas of the inner cover, and KT is the overall heat transfer coefft. In spite of decreasing the unmber of revolutions of the base fan, the decrease in the KT is small if the gaseous temp. exceeds about 700 deg.C (corresponds roughly to a soaking period), and at above 0.6 ratio of the number of revolutions, it is negligible. The force cooling period is expressed by the equation II, and in the case of force cooling cooler cooling, if the gaseous temp. lowers to a certain degree, the decrease in the KT, is small and is virtually negligible in spite of decreasing the number of revolutions of the base fan. Thereby, the annealing capacity is maintained with a certain decrease in the number of revolutions of the base fan. |
