Coal is used in power plants to generate electricity or in manufacturing plants to fire their boilers. In power plants the consumption of coal accounts for about 70% of the costs. The quality of coal not only directly affects the boiler combustion efficiency, but also seriously affects the safe operation of the boiler. Changes in coal quality can decrease the output of boilers, reduce thermal efficiency, cause boiler surface coking, and can produce fouling which can lead to boiler accidents. Thus, coal quality analysis is essential for boiler safety and efficiency.

The parameters that affect the boiler combustion efficiency include energy content, volatile content, ash content, and moisture.

  • Energy content is a key parameter for coal quality. The higher the energy content, the more heat energy that can be produced. It is also an important parameter for boiler design. When the energy content is too low, the combustion is not stable and can lead to boiler flameout. However, if the coal energy content is higher than the boiler can handle then the temperature inside the boiler will increase which can result in slagging. When slagging conditions are severe, the boiler has to be shut down.
  • Volatile content can be released and will burn at low temperatures, which will increase the temperature of the coke and make it easier to burn. When the volatile content is released, the coking surface area will increase, which can affect the burning rate of coke.
  • Ash content will absorb heat during burning. The higher the ash content, the lower the heat the burning of coal can generate. Ash content can also decrease combustion efficiency since it can decrease flame propagation speed.
  • Moisture in small amounts can increase coal combustion efficiency, but moisture content that is too high can be unfavorable.

Compared to traditional methods of coal analysis, FT-NIR spectroscopy is fast, non-destructive, and can test multiple components with a single measurement. Galaxy Scientific offers on-line or off-line coal quality control solutions using portable, high performance FT-NIR. With its fast measurement, boiler control parameters can be adjusted promptly, which will reduce the consumption of coal and improve the economic efficiency of power plants and industrial boilers.

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