Calculating Power Plant Coal Consumption

Very often, the Power engineer is required to perform some basic calculations regarding the key parameters of a power plant. Most important is the quantity and cost of fuel that is required.

Take the example of a 150 MW Coal Fired Power Plant.

The basic function of the power plant is to convert energy in coal to electricity. Therefore, the first thing we should know is how much energy there is in coal. Energy content of coal is given in terms of Kilojoules (kJ) per Kilogram (kg) of coal as the Gross calorific value (GCV) or the Higher Heating value (HHV) of coal. This value can vary from 10500 kJ/kg to 25000 kJ/kg depending on the quality and type of the coal.

Efficiency
Energy conversion takes place in two stages.
The first part of the conversion is efficiency of the boiler and combustion. For this example we take 88 % basis that is the normal range for a well-optimized power plant.
Second part is the steam cycle efficiency. Modern Rankine cycle, adopted in coal fired power plants, have efficiencies that vary from 32 % to 42 %. This depends mainly on the steam parameters. Higher steam pressure and temperatures in the range of 600 ° C and 230 bar have efficiencies around 42 %. We assume a value of 38 % for our case.
The overall conversion efficiency then is (38% x 88%) 33.44 %.

Heat Rate
Heat rate is the heat input required to produce one unit of electricity. (1 kw hr)
One Kw is 3600 kJ/hr. If the energy conversion is 100 % efficient then to produce one unit of electricity we require 3600 kJ.
After considering the conversion efficiency in a power plant we require an heat input of (3600 / 33.44% ) 10765 kJ/ kw hr.

150 MW requires coal consumption: 10765/(10500 kJ/kg to 25000 kJ/kg)x150

This is the theoretical value of the estimation, and the actual power plant coal consumption is related to the quality of coal and the efficiency of boilers.

More information about calculating power plant coal consumption, please email zbg@zzboiler.com or call 86-371-86062323.