Efficiency of a Boiler
Efficiency of a Boiler
(OP)
Can somebody please help me with the calculation of the efficiency of a water tube boiler of 17 bars. Its production capacity is 35t/h. The guy before me use to calculate the efficiency using the effluent gas temperature and the excess air. I am thinking of using the heat absorbed/heat furnished. I will be very happy with a detail explanation of which method is best.





RE: Efficiency of a Boiler
perhaps this website will be of assistance to you.
http://www.heaterdesign.com/design0.htm
see documentation made available within the publications link on main site.
hope this helps.
-pmover
RE: Efficiency of a Boiler
The answer depends on what is important to you.
If its accuracy then the heat loss method is the way to go (gas temperature and excess air); if it is not then the input/output method could be used.
ASME PTC 4 gives the following information regarding the uncertainty (error) for both methods for small gas fired industrial boilers.
Heat loss 0.2 to 0.5 percentage points
Input/output 1.2 percentage points
Best regards,
athomas236
RE: Efficiency of a Boiler
The formula: 100 - (temp.of effluent gas/20 + excess air/2 + 2).
RE: Efficiency of a Boiler
I do not know the formula but if you tell me the following, I will check the efficiencies at 30t/h on GCV basis for a range of flue gas temperatures and excess air values:
1. Fuel ultimate analysis and GCV
2. Superheater outlet steam temperature at 30t/h
3. Economiser inlet water temperature at 30t/h
4. Boiler exit flue gas temperature at 30t/h
5. Boiler excess air at 30t/h
Regards,
athomas236
RE: Efficiency of a Boiler
1-Fuel Analysis: C1=57.71, C2 = 24.36, C3=14.53, C4=3.31, C5=0.07, C6=0.01
2 - Super heater outlet Temperature= 380°C
3 - Economiser inlet water Temperature = 105°C
4 - Boiler exit effluent gas temeprature = 308°C
5 - Excess air = 15%
RE: Efficiency of a Boiler
[PDF] CIBO Energy Efficiency Handbook File Format: PDF/Adobe Acrobat - View as HTML
the members of the CIBO Energy Efficiency Subcommittee for their direction and insight into the process of preparing this Energy Efficiency Handbook; ...
www.cibo.org/pubs/steamhandbook.pdf
[PDF] ENERGY EFFICIENCY & INDUSTRIAL BOILER EFFICIENCY An Industry ... File Format: PDF/Adobe Acrobat -
cibo.org/pubs/whitepaper1.pdf
been their did that
L S THILL
RE: Efficiency of a Boiler
Based on the data supplied and estimated GCV of 52.673MJ/kg I calculate an efficiency of 78.179% compared with that of 75.1% using your formula.
With gas temp of 350C and XSA of 15%, efficiency is 76.318%.
With gas temp of 308C and XSA of 25%, efficiency is 77.259%.
Combining this data gives the following formula:
Efficiecy = 93.203-0.886*Tg/20-0.928*XSA/10
Regards,
athomas236
RE: Efficiency of a Boiler
RE: Efficiency of a Boiler
According with "Boiler Efficiency Calculations Simplified" by V. Ganapathy, for oil fuels #2 and #6, the efficiency is calculated:
Based on the Higher Heating Value
% = 92,9 - (0,001298+0,0195*EA)(Tg-Ta)
Based on Lower Heating Value
% = 99,0 - (0,001383+0,0203*EA)(Tg-Ta)
where: Ta = ambient or Reference temperature.
Tg = exit gas temperature.
EA = excess air factor. For an excess air of 15%, the EA = 1,15.
RE: Efficiency of a Boiler
padovano,
I have a spreadsheet that calculates boiler efficiencies in accordance with ASME PTC4.1.
So I calculated the boiler efficiency based on GCV using the data you provided and obtained a value of 78.179%. Then I increased the excess air from 15% to 25% and obtained 77.259%.
So for change in excess air the change in efficiency is (77.259-78.179)/(25-15)= -0.92/10.
In a similar way I changed the gas temperature from 308C to 350C and obtained an efficiency of 76.318%. So for a change in gas temperature the change in efficiency is (76.318-78.179/(350-308)*20= -0.886. The remaining constant was obtained by algebra.
Regards,
athomas236