Irregularities in Blast Furnace during Operation Nov02

Irregularities in Blast Furnace during Operation...

Irregularities in Blast Furnace during Operation For a stable and efficient operation of a blast furnace, smooth and uniform movement of burden materials downward and movement of furnace gases in the upward direction is very important. To ensure this a lot of work has been done in the recent past. This includes improvement in the characteristics of the burden materials, improvement in the furnace charging system, adequate automation of the furnace operation to eliminate human errors and improvement in the furnace operating procedures. In spite of these improvements, the blast furnace does not run as smoothly as one is led to believe. Furnace upsets are not as frequent as they were in earlier years but irregularities still do occur. These irregularities are the main concern for a blast furnace operator and often need quick thinking and timely good judgment on the part of the operator to prevent serious trouble. The major irregularities in the blast furnace operation are described below, Furnace hanging and slipping When the materials charged at the top of the blast furnace do not move continuously towards the hearth of the furnace, the phenomenon is called ‘hanging’ of the burden. Hanging of the burden material in the blast furnace stack occurs when the material below the hang continues to move downward, forming a space that is void of materials but filled with gas at very high pressure. This space continues to grow unless hang finally collapses. The collapsing of the hang is a phenomenon called ‘slipping’ during which the charged materials fall uncontrollably toward the hearth of the furnace in a thermally unprepared state which leads to the furnace getting cold. It also forces the hot gases upward with the force of an explosion. The sudden rush of gases opens the...