Coal: Difference between revisions
(Created page with "Coal is a mineral, a compected and fossilized form of peat. It is an important source of carbon compounds, containing more per unit weight or volume than dry wood, and containing more recoverable hydrocarbon and aromatic materials. It has the same relationship to '''coke''' that wood has to charcoal. ==Uses== ===Primary=== * As a solid fuel * Feedstock for producer gas * Feedstock for coke, hydrocarbons, and aromatic carbon compounds ===Secondary=== * Feedsto...") |
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* Coal is flammable | * Coal is flammable | ||
* Coal contains numerous volatile compounds which are dangerous to breathe | * Coal contains numerous volatile compounds which are dangerous to breathe | ||
* Coal ash is sufficiently microscopic that it is hazardous to | * Coal ash is sufficiently microscopic that it is hazardous to breathe | ||
* Coal contains nontrivial amounts of [[sulfur]] | * Coal contains nontrivial amounts of [[sulfur]] | ||
==Types== | ==Types== | ||
{| class=wikitable | {| class=wikitable | ||
Latest revision as of 21:39, 3 December 2024
Coal is a mineral, a compected and fossilized form of peat. It is an important source of carbon compounds, containing more per unit weight or volume than dry wood, and containing more recoverable hydrocarbon and aromatic materials. It has the same relationship to coke that wood has to charcoal.
Uses
Primary
- As a solid fuel
- Feedstock for producer gas
- Feedstock for coke, hydrocarbons, and aromatic carbon compounds
Secondary
- Feedstock for ammonia
Natural occurrence
Coal and peat occur naturally. Outcrop coal is a term which describes coal seams with exposed areas caused by erosion or seismic action.
Hazards
- Coal is flammable
- Coal contains numerous volatile compounds which are dangerous to breathe
- Coal ash is sufficiently microscopic that it is hazardous to breathe
- Coal contains nontrivial amounts of sulfur
Types
| Type | Carbon content | Water content | Ash content | Fuel value (MJ/kg) |
|---|---|---|---|---|
| Lignite | 25-35% | High (~45%) | 10-50% | 15-27 |
| Bituminous | 69-86% | Medium (< 20%) | 3-12% | 27 |
| Anthracite | 86-98% | Low (< 15%) | 10-20% | 32-34* |
| Charcoal (for comparison) | 100% | Very Low 1-10% | 0.5-5% | 25-29 |
* The energy for anthracite is paradoxically higher that for pure carbon (charcoal) because additional elements (sulfur, nitrogen, hydrogen) are also oxidized as fuels.
External content
The rank of coal is based on the degree to which the orginal plant material has been transformed into carbon and can be seen as a rough indication of how old the coal is: the older the coal the higher the carbon content (generally). The ranks of coal (from most to least carbon content) are as follows: anthracite, bituminous coal, subbituminous coal, and lignite.
The coal with the highest carbon content is the best and cleanest type of coal to use. As you move down the coal rank the heat given out decreases and the dirtyness of the fuel and moisture content increases.
Lignite coal
Used almost exclusively for electric power generation lignite is a young type of coal. Lignite is brownish black, has a high moisture content (up to 45 %), and a high suphur content. Lignite is more like soil than a rock and tends to disintegrate when exposed to the weather. Lignite is also called brown coal. Lignite has a calorific value of less than 5 kw/kg approximately.--www.stovesonline.co.uk/