This section contains Unit Training manuals of Blast Furnace Deptt

Bell less top charging system is an improvement over the double bell charging system. In this, the material coming from the highline area is transported by skip to the receiving hopper.

When predefined skips are loaded into the receiving hopper, the upper material gate and material seal valve opens in order to discharge the raw material into the material hopper.

There are equalizing and relieve valves for distribution of pressure. Finally, the material gets discharged into the rotating chute through the lower material gate and seal valve. The rotating chute can be set at predefined angles with the help of transmission gears for better burden distribution. This ultimately leads to better permeability of reducing gases and efficient reduction.

The greasing system consists of two different greasing cycles driven by means of 4 3/2 valves. Each cycle has two half cycles to lubricate all the greasing points.

 Cycle 1: Fast cycle ,every 45 minutes (chute transmission, planetary gearbox, lower seal valve, lower material gate, upper material gate ,upper seal valve)

 Cycle 2: Slow cycle, every 8 hours (mechanical stock-line winches, lower seal valve, lower material gate, upper seal valve, upper material gate, primary equalizing valve, secondary equalizing valve, relief valve, bottom pulleys)

As the BLT charging is in continuous contact with the high temperature conditions of the blast furnace top, it requires an efficient cooling system for proper functioning. The cooling system for BLT system is an integral part of blast furnace bell less top design. We are mainly using 2 types of cooling system while operation of blast furnace. They are:

1) Water cooling

2) Nitrogen cooling.

Blast Furnace is a counter current heat and mass exchanger, in which solid raw materials are charged from the top of the furnace and hot blast is sent through the bottom via tuyeres. The heat is transferred from the gas to the burden and oxygen from the burden to the gas. Gas ascends up the furnace while burden and coke descend down through the furnace. The counter current nature of the reactions makes the overall process an extremely efficient one.