Topics in Coal Analysis

Introduction

Coal analysis is very important for designing and operating a fossil fuel power station. If the coal has lots of sulfur in it, then an FGD (Flue Gas Desulfurization) unit becomes necessary. The amounts of ash in the coal also determines the sizing of the ash handling system as well as the coal burners. Also the hardness of the coal determines the type of mills to be used. Also the presence of harmful heavy metals such as Mercury can necessitate special systems for treating the flue gas or the waste water from the FGD.

Importance for Efficiency Calculations

During operations, it is important to know the amount of energy going into the boiler and the amount of electrical energy produced by the power station so as to calculate efficiency.

Sampling and Sample Preparation

Samples have to be representative of the coal quality.

Proximate Analysis Includes

Moisture Content

Ash

Volatile Matter: the volatile product of decomposition of coal under high T

Fixed Carbon: Total weight – moisture – ash – volatile matter – Sulfur

Coal Assay

Gray-king Assay at 600°C (1112°F)

Gray-king Assay at 900°C (1652°F)

Other Carbonization Tests

Ultimate Analysis

Carbon (Organic and Inorganic) and Hydrogen (Hydrocarbon H and water H)

Nitrogen

Sulfur: organic sulfur + sulfides + sulfates

Oxygen (determined by difference)

Chlorine

Mercury

Other Constituents

Mineral Matter

Aluminosilicates (Clay Minerals)

Sulfide Minerals

Sulfate Minerals

Carbonate Minerals

Silicate Minerals

Other Minerals

Physical and Electrical Properties

Thermal Properties – Calorific Value

Mechanical Properties

Spectroscopic Properties

Infrared Spectroscopy

Nuclear Magnetic Resonance

Mass Spectrometry

Ultraviolet Spectroscopy

X-ray Diffraction

Electron Spin Resonance

Solvent Properties

Below is a table with the main properties that are analysed for coal:

Conclusion

Coal generated power is still one of the major sources of energy in developing countries because it is cheap and available. It is possible to generate clean power with coal if the power station is retrofitted with CCUS systems.