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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.
Direct reduction processes can be divided roughly into two categories: gas-based and coal-based. In both cases, the objective of the process is to remove the oxygen contained in various forms of iron ore (sized ore, concentrates, pellets, mill scale, furnace dust, etc.) in order to convert the ore to metallic iron, without melting it (below 1,200 °C (2,190 °F)).
In iron ore smelting, haematite gets reduced at the top of the furnace, where temperature is in the range 600 – 700 °C. The Ellingham diagram indicates that in this range carbon monoxide acts as a stronger reducing agent than carbon since the process 2 CO + O 2 → 2 CO 2. has a more-negative free energy change than the process: 2 C + O 2 ...
A ratio of 1 corresponds to the stoichiometric ratio Constant volume flame temperature of a number of fuels, with air. If we make the assumption that combustion goes to completion (i.e. forming only CO 2 and H 2 O), we can calculate the adiabatic flame temperature by hand either at stoichiometric conditions or lean of stoichiometry (excess air ...
The more economical coke soon replaced charcoal in British furnaces, but in the United States, where timber for charcoal was abundant, charcoal furnaces lingered much longer. Even after the introduction of anthracite smelting to the US in 1839, [ 1 ] and the development of American coke production later in the century, charcoal iron continued ...
Blast furnace (left), and three Cowper stoves (right) used to preheat the air blown into the furnace. Hot blast furnace: note the flow of air from the stove in the background to the two blast furnaces, and hot air from the foreground furnace being drawn off to heat the stove. Hot blast refers to the preheating of air blown into a blast furnace ...
Consider a gas in cylinder with a free floating piston resting on top of a volume of gas V 1 at a temperature T 1. If the gas is heated so that the temperature of the gas goes up to T 2 while the piston is allowed to rise to V 2 as in Figure 1, then the pressure is kept the same in this process due to the free floating piston being allowed to ...