Improvement in life of charging side up-take area of reheating furnaces at Hot Strip Mill, Bokaro Steel Plant

摘要

In Hot Strip Mill (HSM), Bokaro Steel Plant (BSL) of Steel Authority of India Limited (SAIL), there are 3 walking beam type Reheating Furnaces (RHF) of capacity 300 t/hr. each. In the charging side up-take area of these furnaces, conventional castables of 60 per cent and 90 per cent alumina quality were being used. These castables were frequently falling, forcing the furnaces to make down for repairs in every 2-3 months for about 1 0 days each. The application of castable in this area is difficult because of mechanical structure above it. To maintain the flowability ofcastable, more water was being used, deteriorating its properties. Both ceramic as well as metallic anchors were tried, but life could not be obtained. During the year 2011-12, the furnaces had to be made down additional 4 times (total 7 times) because of refractory problem in this area, making the average shutdown of 24 days/furnace/annum. Flue gasses pass through the up-take area at a temperature of about 800-1000°C and the thickness ofcastable lining is about 250 mm.