Lesson 3 - Lesson 3 Learning Objectives Success in this...

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Lesson 3 Learning Objectives Success in this lesson will be based on the following learning goals; Describing the formation of coal and coalbed methane (natural gas) Articulating coal mining methods Discussing coal and natural gas transformations, and transportation methods Explaining coal cleaning options and efficiencies Origins of Coal Coal is the altered remains of prehistoric vegetation that originally accumulated as plant material in swamps and peat bogs. The accumulation of silt and other sediments, together with movements in the earth’s crust (tectonic movements) buried these swamps and peat bogs, often to great depth. Over many more millions of years, the continuing effects of temperature and pressure produced additional changes in the lignite, progressively increasing its maturity and transforming it into the range known as sub-bituminous coals.As this process continued, further chemical and physical changes occurred until these coals became harder and more mature, at which point they are classified as bituminous or hard coals. Under the right conditions, the progressiveincrease in the organic maturity continued, ultimately to form anthracite. Low rank coals, such as lignite and sub-bituminous coals, are typically softer, friable materials with a dull, earthy appearance; they are characterized by high moisture levels and a low carbon content, and hence a low energy content. Higher rank coals are typically harder and stronger and often have a black vitreous lustre. Increasing rank is accompanied by a rise in the carbon and energy contents and a decrease in the moisture content of the coal. Anthracite is at the top of the rank scale and has a correspondingly higher carbon and energy content and a lower level of moisture. Coal Formation The organic matter that falls or is washed into the swamp will be protected from the usual decay process because of the low oxygen concentration in the water. Decay will occur in the less bio-resistant material, leaving behind the bio-resistant organic material. Eventually this material will form peat. With burial and the "cooking" of the earth (as you get deeper, it gets warmer) for geological time periods low rank coals will form. The process of coal formation might repeat itself and so layers of coal and rock are present in many locations within the US. Coal Quality There are 2 officially accepted methods of determining the rank of a coal in the US (but numerous other approaches). Which approach you use depends on the calorific value of the coal. There are 4 general rank classifications, shown from lowest to highest rank;
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Lignite : low rank Subbituminous low rank : Bituminous high rank - soft coal Anthracite : high rank - hard coal The rank of coal is an important feature of the coal, it is used in taxation purposes, contracts etc. Coals that have a calorific value below 14,000 Btu's are classed into rank classification based on the calorific value. Coals with calorific values above 14,000 Btu's
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This note was uploaded on 03/30/2008 for the course EGEE 101 taught by Professor Mathews,jonathan during the Spring '06 term at Penn State.

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Lesson 3 - Lesson 3 Learning Objectives Success in this...

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