-
What is the composition of Blast Furnace Gas (BFG)?
Date posted:
-
-
Post Author
espadmin
1. Introduction
The typical fuel gases used in integrated iron and steelworks are listed in CF62 and introduced in more detail in CF100. This group of industrial fuel gases includes [GLOSS]Blast Furnace Gas[/GLOSS] or [GLOSS]BFG[/GLOSS].
Blast Furnace Gas BFG is produced as a by-product from pig iron production in [GLOSS]blast furnaces[/GLOSS]. Pig iron, or “[GLOSS]hot metal[/GLOSS]” is a base material for steel production in a basic oxygen furnace or an electric arc furnace.
Blast Furnace Gas is a low [GLOSS]calorific value[/GLOSS] fuel gas, which can be used as gaseous fuel in various applications inside or outside the iron making plant. A significant amount of Blast Furnace Gas is used for the production of hot blast in blast furnace stoves.
The production of BFG, its combustion and flue gas properties, and its applications are described in associated Combustion File numbers 218, 243 and 244 respectively. The present CF details the composition of BFG.
2. Composition of Blast Furnace Gas
The composition of Blast Furnace Gas are dependent on the blast furnace feedstock, blast furnace operating conditions and the gas cleaning employed.
The prime aim of a blast furnace manager is to make a good and constant quality pig iron, in sufficient amount, with minimum environmental impact and at low cost. The properties of the Blast Furnace Gas are a result of this.
Due to these factors, fuel gas properties of Blast Furnace Gas are different from site to site and may also vary in time. In Table 1 the average fuel gas composition of six different blast furnaces are shown.
As shown in Table 1, the main combustible species in Blast Furnace Gas are carbon monoxide and hydrogen. From the composition of the Blast Furnace Gas, other properties, such as the [GLOSS]net calorific value[/GLOSS] and [GLOSS]net Wobbe Index/Number[/GLOSS] can be calculated.
The net calorific value of dry Blast Furnace Gas and the Wobbe index vary between 2.8 MJ/m03 and 3.9 MJ/m03. The net calorific value of Blast Furnace Gas is almost equal to the Wobbe index since the relative density of Blast Furnace Gas equals one.
|
|
|
Plant 1 |
Plant 2 |
Plant 3 |
Plant 4 |
Plant 5 |
Plant 6 |
|
Carbon Monoxide |
% v/v |
26.2 |
22.7 |
20.0 |
20.8 |
20.8 |
21.4 |
|
Hydrogen |
% v/v |
5.7 |
3.2 |
6.0 |
0.9 |
0.4 |
2.7 |
|
Methane |
% v/v |
0.0 |
0.0 |
1.7 |
0.2 |
1.3 |
0.0 |
|
Ethane |
% v/v |
0.0 |
0.0 |
0.2 |
0.0 |
0.0 |
0.0 |
|
Carbon Dioxide |
% v/v |
23.1 |
15.3 |
18.1 |
18.1 |
18.2 |
16.7 |
|
Nitrogen |
% v/v |
41.9 |
51.6 |
47.8 |
52.9 |
52.1 |
53.1 |
|
Water Vapour |
% v/v |
2.3 |
7.3 |
6.3 |
7.0 |
7.3 |
6.1 |
|
Argon |
% v/v |
0.8 |
0.0 |
0.0 |
0.0 |
0.0 |
0.0 |
Table 1 Average Blast Furnace Gas composition of different blast furnaces
Sources
[1] American Iron and Steel Institute, www.steel.org
[2] Ricketts, J.A., How a blast furnace works, Ispat Inland Inc.
[3] N.V. Nederlandse Gasunie, Physical properties of natural gases, Groningen, Netherlands, 1980.
[4] Zabetakis, M.G., Flammability characteristics of combustible gases and vapors, Bulletin 627, Bureau of Mines, 1965.
[5] Informatie Chemische Stoffen, werkinstructiekaart oxygas, Corus, 2002.