Suddo
Chemical
- Jul 31, 2019
- 13
This is regarding a fluidised bed coal fired heater (Cap. 10 Mkcal/hr), used to heat thermic fluid, for which I have calculated the following numbers.
As we know, there are two methods to calculate the efficiency, the Direct method, and the Indirect method.
The Calculated values come out as follows, around 70% by direct and around 82-83% by indirect method. Seeing it from the heat balance angle, such a difference is problematic. The losses considered in indirect method include :
L1 : Loss of heat due to dry flue gas
L2 : Loss of heat due to evaporation of water formed due to H2 in fuel
L3 : Loss of heat due to moisture in fuel
L4 : Loss of heat due to moisture in air
L5 : Loss of heat due to radiation
L6 : Loss of heat due to un-burnt ash.
Direct efficiency is simply calculated by dividing the heat output (M Cp delta T) by the heat input ( Coal weight * GCV).
What could be the possible explanation of this difference? Also, which efficiency is more reliable then?
As we know, there are two methods to calculate the efficiency, the Direct method, and the Indirect method.
The Calculated values come out as follows, around 70% by direct and around 82-83% by indirect method. Seeing it from the heat balance angle, such a difference is problematic. The losses considered in indirect method include :
L1 : Loss of heat due to dry flue gas
L2 : Loss of heat due to evaporation of water formed due to H2 in fuel
L3 : Loss of heat due to moisture in fuel
L4 : Loss of heat due to moisture in air
L5 : Loss of heat due to radiation
L6 : Loss of heat due to un-burnt ash.
Direct efficiency is simply calculated by dividing the heat output (M Cp delta T) by the heat input ( Coal weight * GCV).
What could be the possible explanation of this difference? Also, which efficiency is more reliable then?