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Blast furnace gas (BFG) [1] is a by-product of blast furnaces that is generated when the iron ore is reduced with coke to metallic iron. It has a very low heating value , about 3.5 MJ/m 3 (93 BTU /cu.ft), [ 2 ] because it consists of about 51 vol% nitrogen and 22 vol% carbon dioxide , which are not flammable.
Blast furnaces differ from bloomeries and reverberatory furnaces in that in a blast furnace, flue gas is in direct contact with the ore and iron, allowing carbon monoxide to diffuse into the ore and reduce the iron oxide. The blast furnace operates as a countercurrent exchange process whereas a bloomery does not.
For blast furnaces, direct reduction corresponds to the reduction of oxides by the carbon in the coke. However, in practice, direct reduction only plays a significant role in the final stage of iron reduction in a blast furnace, by helping to reduce wustite (FeO) to iron. In this case, the chemical reaction can be trivially described as follows ...
James Beaumont Neilson, previously foreman at Glasgow gas works, invented the system of preheating the blast for a furnace.He found that by increasing the temperature of the incoming air to 149 °C (300 °F), he could reduce the fuel consumption from 8.06 tons of coal to 5.16 tons of coal per ton of produced iron with further reductions at even higher temperatures. [4]
As blast furnaces re-equipped after World War II, the favoured power source was either the diesel engine or the electric motor. These both had a rotary output, which worked well with contemporary developments in centrifugal fans capable of handling the huge volumes of air. Although the reciprocating steam blowing engine continued where it was ...
The process starts by charging solid sinter and heated coke into the top of the blast furnace. Preheated air at 190 to 1,050 °C (370 to 1,920 °F) is blown into the bottom of the furnace. Zinc vapour and sulfides leave through the top and enter the condenser. Slag and lead collect at the bottom of the furnace and are tapped off regularly.
The PCI method is based on the simple concept of primary air (termed the "conveying gas") carrying pulverized coal which injected through a lance to the tuyere (mid-bottom inlet of a blast furnace), then mixed with secondary hot air (termed the "blast") supplied through a blowpipe in the tuyere and then piped to a furnace to create a balloon ...
A metallurgical furnace, often simply referred to as a furnace when the context is known, is an industrial furnace used to heat, melt, or otherwise process metals. Furnaces have been a central piece of equipment throughout the history of metallurgy ; processing metals with heat is even its own engineering specialty known as pyrometallurgy .