Proximate Coal Analysis Quiz

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Questions and Answers

What is considered the rank (quality) of coal largely affected by?

Chlorine content

Carbon content

Sulfur content

Moisture content (correct)

What is the correct order of mass fractions for the proximate analysis of Indian coal?

Moisture 14%, Fixed carbon 31%, Volatile matter 21%, Ash 42% (correct)

Ash 42%, Volatile matter 21%, Fixed carbon 31%, Moisture 14%

Fixed carbon 31%, Ash 42%, Moisture 14%, Volatile matter 21%

Volatile matter 21%, Ash 42%, Moisture 14%, Fixed carbon 31%

At what temperature should volatile matter in coal be analyzed?

100°C

700°C

800°C

900°C (correct)

Which component's analysis requires the crucible to be closed with a lid during heating?

Volatile matter Signup and view all the answers

What is the dwell time for ash analysis in the furnace?

60 minutes Signup and view all the answers

How can the mass fraction of moisture, Y_M, be expressed mathematically?

Y_M = 1 - (residue mass)_Expt_1 / (sample mass)_Expt_1 Signup and view all the answers

Which mass fraction formula accounts for the fixed carbon content?

Y_FC = 1 - (residue mass)_Expt_3 / (sample mass)_Expt_3 Signup and view all the answers

What is the correct calculation to find the ash content, Y_A?

Y_A = 1 - Y_M - Y_VM - Y_FC Signup and view all the answers

What is the primary difference between Y_VM and Y_M?

Y_VM accounts for the residue mass from Experiment 2. Signup and view all the answers

In finding Y_VF, which step needs to be taken after determining Y_M?

Subtract the mass fractions of both moisture and volatile matter from 1. Signup and view all the answers

Which component of coal primarily determines its calorific value?

Fixed carbon Signup and view all the answers

How does excessive moisture content in coal affect its use?

It may extinguish the fire in the furnace. Signup and view all the answers

What is referred to as the 'gross calorific value' of a fuel?

The total heat released when products are cooled to 25 °C. Signup and view all the answers

Which of the following increases with the rank of coal?

Fixed carbon Signup and view all the answers

Why do components other than carbon and hydrogen decrease the rank of coal?

They lower the overall calorific value. Signup and view all the answers

Ash content in coal primarily consists of which materials?

Silica and alumina Signup and view all the answers

The products of combustion from carbon and hydrogen in coal are primarily what substances?

Carbon dioxide and water vapor Signup and view all the answers

What effect does high ash content have on furnace efficiency?

It decreases the efficiency of furnaces. Signup and view all the answers

Study Notes

Proximate Coal Analysis

Aim: To determine the composition of a coal sample by measuring its moisture, volatile matter, ash, and fixed carbon content.
Key Components:
- Moisture: Water content in coal, impacting transportation cost and combustion efficiency.
- Volatile Matter: Components released when coal is heated in the absence of oxygen, decreasing the coal's rank.
- Ash: Inorganic matter in coal, reducing combustion efficiency.
- Fixed Carbon: The remaining combustible material after volatile matter is removed, increasing with coal rank.
Proximate Analysis vs. Ultimate Analysis:
- Proximate analysis: determines the mass fractions of moisture, volatile matter, ash, and fixed carbon.
- Ultimate analysis: determines the mass fractions of elements like C, H, O, N, S, Cl, etc.

Procedure

Steps:
1. Weigh an empty crucible.
2. Add a known mass of coal sample to the crucible and weigh it again.
3. Place the crucible in a furnace at specific temperatures and dwell times for each component:
  - Moisture: 100°C, 60 minutes
  - Volatile matter: 900°C, 10 minutes
  - Ash: 700°C, 60 minutes
4. Allow the crucible to cool in a desiccator and weigh the residue.
5. Repeat steps 1-4 to analyze each component.

Calculation

Mass fractions are calculated using the following formulas:
- Y_M: Moisture content = 1 - (Residue mass_Expt.1 / Sample mass_Expt.1)
- Y_VM: Volatile matter content = 1 - (Residue mass_Expt.2 / Sample mass_Expt.2) - Y_M
- Y_FC: Fixed Carbon content = 1 - (Residue mass_Expt.3 / Sample mass_Expt.3) - Y_M - Y_VM
- Y_A: Ash content = 1 - Y_M - Y_VM - Y_FC

Results

Proximate analysis provides the following information:
- Moisture content (in %)
- Volatile matter content (in %)
- Fixed Carbon content (in %)
- Ash content (in %)

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Description

Test your knowledge on proximate coal analysis and its key components such as moisture, volatile matter, ash, and fixed carbon. Understand the differences between proximate and ultimate analysis while learning about the significance of these factors in coal composition and combustion efficiency.