In order to cope with superannuated coke ovens and to reduce pig iron cost, high-rate pulverized coal injection technology and operation technology utilizing inexpensive raw materials and fuels have been examined. The influence on the blast furnace operation to which such technology is applied is that gas permeability in a lower part of the blast furnace, especially inside the deadman of the blast furnace, deteriorates and the temperature of the part decreases. To lessen these drawbacks, new deadman methods for controlling temperature and improving gas permeability were developed. In one of these methods, called the "insert and blowing method", a pipe is inserted into the deadman through a tuyere and then hot gas is blown through the pipe. In another method, called the "boring and blowing method", a coke bed in a lower part of the furnace is bored using a pipe before hot gas is blown through an ordinary tuyere. To confirm and to evaluate the effects of these methods, many experiments using models have been conducted. The results show that gas permeability was improved and the temperature in the lower part of the models was increased. The effectiveness of these methods was increased by adding water vapor to the blowing air when the surface of the deadman was covered with fine coke or char.
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