Blast furnace gas
Blast furnace gas 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 93 BTU/cubic foot, because it consists of about 60 percent nitrogen and 18-20% carbon dioxide, which are not flammable. The rest is mostly carbon monoxide, which has a fairly low heating value already and some hydrogen. It is commonly used as a fuel within the steel works, but it can be used in boilers and power plants equipped to burn it. It may be combined with natural gas or coke oven gas before combustion or a flame support with richer gas or oil is provided to sustain combustion. Particulate matter is removed so that it can be burned more cleanly. Blast furnace gas is sometimes flared without generating heat or electricity.
Blast furnace gas is generated at higher pressure and at about in a modern blast furnace. This pressure is utilized to operate a generator, which can generate electrical energy up to 35 kWh/t of pig iron without burning any fuel. Dry type TRTs can generate more power than wet type TRT.
Auto ignition point of blast furnace gas is approximate and it has LEL of 27% & UEL of 75% in an air-gas mixture at normal temperature and pressure.
The high concentration of carbon monoxide makes the gas hazardous.
