Flue Gas Conditions

depending on load, efficiencies and burner adjustment

Efficiencies

- at different heating media temperatures
(steam, thermal oil etc.)

- when boilers is not clean (fouling)

- and at part load.

Flue Gas Data at
10% excess air (~2% O2)
at 50% to 100% load

Flue Gas Data at
20% excess air (~4% O2)
at 50% to 100% load

Outlet
Temperature

°C

Flue Gas Amount
kg/h

per kW load (output)

Outlet
Temperature

°C

Flue Gas Amount
kg/h

per kW load (output)

Efficiencies

88% - 93%
85% - 88%

-1 to -2%

+1 to + 2%

Heating Media :

Low temperatures < 250°C
High temperatures > 250°C

Dirty condition

50% part load

230 - 300
320 - 370

+ 50

- 50

1,6
1,7

+ 0,1

- 0,1

200 - 250
290 - 340

+ 50

- 50

1,8
1,9

+ 0,1

- 0,1

The above data are estimated value only - and can be used for Utilizing Waste Heat in the flue gas - in Economizers etc

Example:
1000 kW steam boiler 180°C steam temperature at 50% part load, dirty condition and an oxygen % at 4% on the burner gives:
1000 x 0,5 x (1,8+0,1-0,1) = 900 kg/h flue gas at temperature of approximately (230+300)/2+50-50 ~ 265°C (+/- 35°C)

Read more about Waste Heat Recovery and Economizers.

tools for thermal engineers