Questions and Answers
What are the components analyzed in proximate analysis of coal?
Fixed Carbon, Volatiles, Ash, and Moisture Content
What does high volatile matter content indicate in coal?
Easy ignition of fuel
The loss in weight from the powdered raw coal sample during moisture measurement represents _____.
moisture
At what temperature is the sample of crushed coal heated to measure volatile matter?
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What is the main heat generator during the burning of coal?
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What is the residue after burning all carbon in a crucible called?
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Match the rank of coal with its proximate analytical values:
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What type of coal developed from terrestrial plant debris that was exposed to the atmosphere?
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What is ultimate analysis used for in coal?
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Study Notes
Proximate Analysis of Coal
- Measures Fixed Carbon, Volatiles, Ash, and Moisture Content as weight percentages (Wt%).
- Fixed Carbon is vital for heat generation during combustion.
- High Volatile Matter indicates easier ignition of coal, enhancing combustion efficiency.
- Ash content is crucial for furnace design, combustion volume, and pollution control systems.
Proximate Analysis Measurements
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Moisture Measurement:
- Powdered raw coal is placed in an uncovered crucible and heated at 108±2 °C.
- After cooling, the loss in weight indicates moisture content.
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Volatile Matter Measurement:
- Crushed coal is weighed, placed in a covered crucible, and heated at 900 ± 15 °C.
- Weight loss represents volatile matter and moisture; remaining mass is coke.
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Carbon and Ash Measurement:
- The crucible is heated until all carbon burns off, leaving incombustible ash.
- Fixed Carbon is calculated by subtracting moisture, volatile matter, and ash from 100%.
Rank-wise Average Proximate Values
- Lignite: Fixed Carbon 29%, Volatile Matter 26%, Moisture 46%
- Subbituminous: Fixed Carbon 42%, Volatile Matter 34%, Moisture 23%
- Low-rank/Volatile Bituminous: Fixed Carbon 47%, Volatile Matter 41%, Moisture 12%
- Medium-rank/Volatile Bituminous: Fixed Carbon 54%, Volatile Matter 41%, Moisture 5%
- High-rank/Volatile Bituminous: Fixed Carbon 65%, Volatile Matter 32%, Moisture 3%
- Semianthracite: Fixed Carbon 86%, Volatile Matter 12%, Moisture 3%
- Anthracite: Fixed Carbon 96%, Volatile Matter 1.2%, Moisture 3%
Ultimate Analysis of Coal
- Analyzes elemental constituents: Carbon, Hydrogen, Oxygen, Sulphur, etc.
- Essential for calculating air requirements for combustion.
- Provides data needed for combustion gas volume and composition, influencing flame temperature.
Types of Coal
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Humic Coal:
- Arises from terrestrial plant debris subjected to atmospheric conditions and peat formation.
- Derived from higher plant kingdom materials.
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Sapropelic Coal:
- Formed from plankton, algae, and terrestrial plants in aerobic or lacustrine environments.
- Examples include bog head coal and canal coals.
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Description
This quiz covers the chemical characterization of coal, focusing on the proximate and ultimate analyses. Learn about the significance of fixed carbon, volatiles, ash, and moisture content in determining the heating value of coal. Test your knowledge on the factors that affect coal combustion and quality.
