Calculation formula :
This method
calculates boiler efficiency by using the basic efficiency formula-
η=(Energy
output)/(Energy input) X 100
In order to
calculate boiler efficiency by this method, we divide the total energy output
of a boiler by total energy input given to the boiler, multiplied by hundred.
Calculation
of direct efficiency-
E= [Q
(Hg-hf)/q*GCV]*100
Where,
Q= Quantity
of steam generated (kg/hr)
Hg= Enthalpy
of steam (Kcal/kg)
hf= Enthalpy
of water (kcal/kg)
q= Quantity of fuel
GCV= Gross
calorific value of the fuel
Enthalpy : Heat Content of system at constant pressure
H :
U + PV
U : Internal Energy ( E) , P : External Pressure , V : Volume
GCV : The
amount of heat energy produced on complete combustion of 1 kg of fuel
Example : 1
Total Steam Generate : 30000 kg
Total fuel Consumption : 2000 ltr ( HSD ) High Speed Diesel
E= [Q
(Hg-hf)/q*GCV]*100
Q : 30000 kg
Steam Pressure : 8 kg/cm2
q : 2000 ltr Feed Water Temperature : 60 degree
1> Enthalpy of steam on 8 kg/cm2 : 661 Kcal/Kg
2> Enthalpy of Water at 60 degree : 60 Kcal/ kg
3> GCV Value of fuel ( HSD ) :
10800 Kcal/kg
Step : 1 Hg : 661 ,
hf : 60 > 661-60 = 601
= (30000( 661-60)/ 2000 x 10800)X100
= ( 30000( 601)/21600000) x 100
= (18030000/ 21600000) X 100
= 83.4 %
Example : 2
Total Steam Generate : 30000 kg
Total fuel Consumption : 3500 kg Coal
E= [Q
(Hg-hf)/q*GCV]*100
Q : 30000 kg
Steam Pressure : 8 kg/cm2
q : 3500 kg Feed Water Temperature : 60 degree
1> Enthalpy of steam on 8 kg/cm2 : 661 Kcal/Kg
2> Enthalpy of Water at 60 degree : 60 Kcal/ kg
3> GCV Value of fuel ( coal ) :
5800 Kcal/kg
Step : 1 Hg : 661 ,
hf : 60 > 661-60 = 601
= (30000( 661-60)/ 3500 x 5800)X100
= ( 30000( 601)/20300000) x 100
= (18030000/ 20300000) X 100
= 88.81 %
Steam Enthalpy Chart
GCV Value of fuel
HSD : Gross
calorific value of Diesel or HSD is 10800 Kcal/kg
Coal
: Gross calorific value coal is 5800 Kcal/kg
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