Coke (fuel)



  Coke is a solid carbonaceous material derived from bituminous coal.

The volatile constituents of the coal—including water, blast furnaces. Today, the hydrocarbons are considered to be by-products of modern coke-making facilities (though they are usually captured and used to produce valuable products). Non by-product coke ovens, such as in the lower photograph, burn hydrocarbon off-gases on site to provide the heat needed to drive the carbonization process.

   

Properties and usage

Coke typically has a specific density between 1.85 and 1.9. It is highly porous.

Since smoke-producing constituents are driven off during the coking of coal, coke forms a desirable fuel for stoves and bituminous coal itself. Coke may be burned with little or no smoke under combustion conditions which would result in a large amount of smoke if bituminous coal were the fuel.

Bituminous coal must meet a set of criteria for use as coking coal, determined by particular plasticity.

Coke is used as a fuel and as a iron ore in a blast furnace. Coke from coal is gray, hard, and porous.

Discovered by accident to have superior heat shielding properties when combined with other materials, coke was one of the materials used in the heat shielding on NASA's Apollo program space vehicles. In its final form, this material was called AVCOAT 5026-39. This material has been used most recently as the heat shielding on the Mars PATHFINDER vehicle. Although not used for modern day space shuttles, NASA is utilizing coke and other materials for a new heat shield for its next generation space craft, named Orion, which is due to be completed in 2014.

History

The use of coke as a fuel was pioneered in 17th century England in response to the ever-growing problem of European deforestation. Wood was becoming increasingly scarce and expensive. Coal's fumes, particularly smoke and sulphur compounds, disqualified it from many applications, including cooking and iron was one of the factors leading to the Industrial Revolution.

Other coking processes

The solid residue remaining from refinement of petroleum by the "syngas also produce coke as an end product, called gas house coke.

Fluid coking is a process by which heavy residual crude is converted into lighter products such as naptha, hydrocarbon gases. The "fluid" term refers to the fact that coke particles are in a continuous system versus older batch-coking technology.

Gases from coke

Coke may be used to make fuel gases. It appears that the names have different meanings in the USA and the UK so confusion is possible. The following are UK meanings:

  • hydrogen, made by passing steam over red-hot coke (or any carbon based char)
  • Producer gas, nitrogen, made by passing air over red-hot coke (or any carbon based char)

These are useful gases but require careful handling because of the risk of carbon monoxide poisoning.

References

  • Coking coal manufacturing procedure


 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Coke_(fuel)". A list of authors is available in Wikipedia.