Term
| What is coal's chemical composition affected by? |
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Definition
1. the differences in the incorporated plant materials
2. the degree of carbonization that has occurred
3. the impurities absorbed from the surroundings during the formation process |
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Term
| In coal, what are two major changes that occur as carbonization goes on? |
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Definition
1. The percentage of carbon increases
2. The percentage of carbon decreases |
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Term
| Stages in coal formation from lowest carbon content and rank to highest. |
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Definition
1. Peat (lowest)
2. Lignite
3. Bituminous coal (soft coal)
4. Anthracite (hard coal) |
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Term
| What is the calorific value of anthracite? |
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Definition
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Term
| What are some of the elements that are present in coal? |
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Definition
| Carbon, Hydrogen, Oxygen, and Nitrogen |
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Term
| Where do the elements in coal come from? |
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Definition
| Some of the elements were contained in the original plants while others were incorporated during the carbonization process; the latter elements came from minerals deposited at the time of peat formation or from secondary minerals that crystallized by percolating through coal seams |
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Term
| What is important when the environmental impact of coal burning is considered? |
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Definition
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Term
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Definition
| The solid residue that is left behind after burning |
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Term
| How much coal ash can there be? |
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Definition
| Can be more than, equal to, or less than the amount of mineral matter in the coal; most coal contains between 5% and 10% ash |
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Term
| What is the basic molecular skeleton of coal? |
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Definition
| Made up of various arrangements of the carbon six ring of aromatic hydrocarbons; the aromatic hydrocarbons may be fused with other rings to form discrete clusters |
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Term
| In the chemical composition of coal, what is found in some of the rings (in place of carbon atoms) or between clusters? |
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Definition
| nitrogen, sulfur, and various metals |
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Term
| In the coal's chemical composition, what are the outer rings of the clusters bonded to? |
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Definition
| Hydrogen atoms or other chemical groups |
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Term
| What does the amount of sulfur in coal depend on? |
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Definition
| The type of plants originally involved and the conditions under which carbonization proceeded |
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Term
| What are the sulfur content ranges of coal? |
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Definition
| less than 1% to about 7% by weight |
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Term
| When does sulfur become a problem in coal? |
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Definition
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Term
| What happens to sulfur during combustion? |
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Definition
| Any sulfur in the coal is converted to gaseous sulfur oxides mainly sulfur dioxide and a small amount of sulfur trioxide |
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Term
| What are sulfur dioxide and sulfur trioxide? |
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Definition
| air pollutant gases that occur during coal combustion; excessive amounts are hazardous to both human health and plant life |
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Term
| What are the 3 approaches to the problems of decreasing sulfur oxide emissions from the coal burning process? |
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Definition
1. Use only coal that has low sulfur content
2. Remove sulfur from high sulfur coal
3. Remove sulfur oxides after burning high sulfur coal from the exhaust gases before releasing them to the atmosphere |
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Term
| What will coal burned in new power plants have to contain in regards to sulfur? |
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Definition
| Less than .7% sulfur and have a high heat content to meet emission standards if no coal pretreatment or exhaust gas cleanup is used |
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Term
| What is the sulfur standard for new large power plants (coal)? |
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Definition
| 0.6 pounds of sulfur for each million Btu of heat obtained |
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Term
| Does the use of low-sulfur coal present a universal solution? |
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Definition
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Term
| What are the two basic approaches to the problem of sulfur? |
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Definition
1. Physical cleaning
2. chemical cleaning |
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