Calorific value of coal calculations

What is Calorific Value or Heating value?

• The calorific value is used to find the amount of heat energy produced after the complete combustion of one kg of fuel.

Gross Calorific Values (GCV/HHV)

• Gross calorific value (GCV)  is  also called as a higher Heating Value (HCV)
• It measures the amount of heat released by the complete combustion of a unit of fuel. GCV considers that all water vapor (H2O) produced during the combustion process is fully condensed
• The flue gas formed from combustion is condensed during waste heat recovery and water condensate is formed. In such cases as coal-fired boilers, the GCV value is used to find out the firing capacity.

Formula for GCV or HCV

Dulong’s formula  is used to calculate  the  GCV (Kcal/kg) of coal

        GCV  = 1/100* (8080*C + 34500* (H – O/8)+ 2240*S)   Kcal/kg

where C, H, O, and S are percentages of carbon, hydrogen, oxygen, and sulfur  in coal

Net Calorific Value (NCV)

• It is called a lower heating value (LHV) or lower calorific value (LCV)
• Its value is calculated by subtracting the latent heat of vaporization of the water vapor from the higher heating value (HHV)
• It assumes water vapor leaves with the combustion products is the gas phase that it is not condensed
• For furnaces firing with gaseous fuel, a lower heating value is used to find the firing capacity. The flue gas formed from combustion is not further condensed.

Formula for LCV

     LCV =  GCV – 9/100*H*587  Kcal/kg

where H  is the percentage of carbon, hydrogen, oxygen, and sulfur  in coal

 GCV and LCV Calculator