DETECTION OF CRACK IN BOTTOM BRICK OF BLAST FURNACE

PURPOSE:To detect safely and easily the cracking condition of the refractory brick in the bottom of a blast furnace by observing the delay in the change with time of the atmosphere pressure near the rear of the refractory brick in the furnace bottom with respect to the change with time of the blast pressure to the furnace. CONSTITUTION:Air is blasted through a tuyere 2 under blast pressure PB to the inside of a blast furnace 1. The atmosphere pressure PR near the rear 6 of the refractory furnace 5 in the furnace bottom below the tuyere 2 is measured with a pressure gage provided to a thermocouple attaching pipe 9 of which one end arrives at said part. When the PB changes on starting and stopping of the blast, the PR changes as well through the pores but a time delay arises in the change of the PR with respect to the change of the PB owing to the resistance of the gaseous flow. If a crack arises in the brick 5 and the atmosphere pressures near the rear 6 in the part where the crack 12 arises and where the crack does not arise are designated as PR1 and PR2, PR3, the above-described time delay of the latter shows the value larger than that of the former two and therefore the crack 12 is detectable.