Manual

The formula for K4 is based on the gross calorific value Qgr. To obtain
the loss based on net calorific value multiply by Qgr/Qnet. Since this
loss is usually small, this conversion has been ignored. This loss is
subtracted from the efficiency.
CO AIR-FREE and Converting to mg/m
3
Certain standards (ANSI Z21.1) for Carbon Monoxide are stated in
terms of air-free. Air-free refers to the concentration of CO in combus-
tion gases undiluted with flue, or other gases containing little CO.
This value is computed using an equation that takes into account the O
2
concentration of the flue gas.
If 5% is measured (O2m) in the flue then the CO gas value will be recal-
culated as if 0% were measured. The equation for air-free is as follows:
COa = CO PPM x [(20.9) / (20.9 - O2m)]
Annual Re-Calibration
While the sensor has an expected life of more than two years in
normal use it is recommended that the analyzer is re-calibrated at
least annually, This is so that long-term drift on the sensor and
electronics can be eliminated. local regulations may require more
frequent re-calibration and users should check with appropriate
authorities to ensure the comply with relevant guidelines.
C50/C75-MAN P. 7
Efficiency Calculation:
Known Data - Fuel: Qgr = Gross Calorific Value (kJ/kg)
Qnet = Net Calorific Value (kJ/kg)
K1 = Constant based on Gross or net Calorific Va l u e
K1g = (255 x % Carbon in fuel)/Qgr
K1n = (255 x % Carbon in fuel)/Qnet
K2 = % max theoretical CO2 ( d r y basis)
K3 = % Wet loss
H
2
= % Hydrogen
H
2
O = % Wa t e r
Measured Data: Tf = Flue Temperature
Ti = Inlet Temperature
O
2
m = % Oxygen in flue gas
O
2
r = Oxygen reference %
Calculated Data: Tnet = Net Temperature
% CO
2
content in flue gas
% Dry flue gas losses
% Wet losses
% Unburned carbon loss
% Efficiency
Tnet = Flue Temperature - Inlet Temperature
(or ambient)
D ry flue gas loss % = 20.9 x K1 x (Tnet)/K2 x (20.9 - O
2
m)
Wet loss % = 9 x H
2
+ H
2
O/Qgr x [2488 + 2.1 Tf - 4.2 Ti]
S i m p l i f i e d = [(9 x H
2
+ H
2
O)/Qgr] x 2425 x [1 + 0.001 Tnet]
Wet loss % = K3 (1 + 0.001 x Tnet)
Where K3 = [(9 x H
2
+ H
2
O)/Qgr] x 2425
Net efficiency % = 100 - dry flue gas losses
= 100 - 20.9 x K1n x (Tnet)/K2 x (20.9 - O
2
m)
Gross efficiency % = 100 - {dry flue gas losses + wet losses}
= 100 - {[20.9 x K1g x (Tnet)/K2 x (20.9 - O2m)]
+ [K3 x (1 + 0.001 x Tnett)]}
Excess Air = [20.9/(20.9 - O
2
m) - 1] x 100
CO
2
% = [(20.9 - O
2
m) x K2/20.9]
U n b u r n e d = K4 x CO/(CO + CO
2
) Note: CO scaled in %
fuel loss %
Where K4 = 70 for coke
= 65 for anthracite
= 63 for Bituminous coal
= 62 for coal tar fuel
= 48 for liquid petroleum fuel
= 32 for natural gas