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Parts of a Blast Furnace

Blast furnaces are large industrial tools for smelting metals. Most often a blast furnace uses high temperatures to smelt iron, which is part of the process for making the commercial steel that is common in the construction and manufacturing industries. Blast furnaces have several components that use basic principles of physics and chemistry.

  1. Stack

    • The stack is the name given to the central compartment of the blast furnace, within which all of the chemical process take place. The stack is made of steel, and it supplies the physical structure for the rest of the blast furnace.

    Lining

    • A blast furnace's stack is lined with bricks. This helps retain as much of the heat inside the furnace as possible. Additional layers may be added outside the brick lining, or between the steel stack and brick lining.

    Bells

    • At the top of the blast furnace, a series of bells, or airlocks, allow furnace operators to control the flow of raw material into the furnace. Besides preventing raw metal from clogging the furnace's throat (the tube leading down into the stack), bells also seal gas inside the furnace.

    Exhaust

    • As a blast furnace operates, it continually produces exhaust in the form of spent fuel. Much like an automobile, this exhaust needs to be vented to allow the furnace to continue running efficiently. A series of steel uptake tubes allow exhaust to rise toward the top of the blast furnace stack where they merge into a larger tube known as the offtake. Offtakes merge into a downcomer, which is a tube that allows the gas to travel downward to a series of filters and bleeder valves that prevent an excessive buildup of pressure inside the furnace.

    Cold Blast Main

    • The cold blast main is a turbofan module that forces cool air into the furnace to supply oxygen for the combustion process. A mixer line supplies a second stream of gas used to regulate the pressure and temperature of air entering the furnace.

    Casthouse

    • A blast furnace's casthouse is located at the bottom of the stack. It is a housing that contains the trough and a series of slag pots, where molten slag flows out of the furnace for cooling and casting.

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