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Gas Circulation of a Blast Furnace

Bryan Jones
5 May 2020

Gas Circulation of a Blast Furnace

Blast Furnace. A smelting furnace in the form of a tower into which a blast of hot compressed air can be introduced from below. Such furnaces are used chiefly to make iron from a mixture of iron ore, coke, and limestone. 

The purpose of the stoves in the blast furnace operation is to maximise the amount of heat recycled whilst supplying hot blast to furnace itself.

Waste gas exits the top of the blast furnace and is cleaned in the gas cleaning plant.

Surplus gas is fed off to feed the works energy requirements.

The remaining gas enters the base of a stove and is mixed with combustion air. 

The hot gas passes through the stove and transfers heat to the refractory chequer work. 

A pre-heated stove is then used as a means of heating incoming air to be used as the hot blast in the furnace. 

Cold incoming air passes over the hot chequer work refractory exiting the stove at 1100oC and into the furnace through the tuyures. 

As the temperature of the supplying stove drops the gas supply is switched so that the stove being heated now becomes the stove heating the incoming air. 

The switch over of stoves occurs approximately every 40 minutes. 

Blast furnaces require a minimum of two stoves but typically operate with three. 1 supplying, 1 on gas and 1 on standby.