The Composition of Coking Gas
Coking gas is produced as a by-product of the coking of coal in a coking oven to produce coke. The completion of the carbonizing process of the coal in the coking oven also results in the formation of many gases, known as coking gas. The coking gas is separated by a condensing system and is used for the production of heat and electricity.
The coking gas is composed of a mixture of gases with different chemical properties, classifications, and concentrations. The main components of coking gas are hydrocarbons, carbon dioxide, and nitrogen, but there are other minor components such as hydrogen, oxygen and sulfur that can also be found.
The composition of coking gas is approximately as follows: nitrogen (N2) 65-75%, carbon dioxide (CO2) 12-20%, hydrogen (H2) 5-10%, oxygen (O2) 2-3%, methane (CH4) 1-3%, ethane (C2H6) 0-1.5%, aromatic compounds (C3H8+) 1-2%, and the rest is composed of other gases in small amounts.
When the coking gas is cooled and condensed, condensate liquid is produced which is composed of wax, oil and tar. The wax, oil, and tar are composed of hydrocarbons, of which the wax has a higher hydrocarbon chain length than the oil, and the tar has an even higher hydrocarbon chain length than the oil. The condensate liquid also contains particulate-ash, which is composed of ash, heavy metals, silicon dioxide, and other solids.
In summary, coking gas is produced during the coking process from the carbonization of coal in a coke oven. The coking gas is composed of nitrogen, carbon dioxide, hydrogen, oxygen, methane, ethane, aromatic compounds, and other gases in small concentrations. When the coking gas is cooled and condensed, it produces condensate liquid wax, oil, tar, and particulate-ash.
