UEi Test Instruments KM940 - Manual (Page 33)

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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
Dry 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 + 2.1Tf - 4.2 Ti]
simplified = [(9 x H
2
+ H
2
O) / Qgr] x 2425 x [1 + 0.001 Tnet]
Wet loss %
= K3(1+0.001xTnet)
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 - O
2
m)]+
[K3 x (1 + 0.001 x Tnett)]}
Excess Air
= [(20.9% / (20.9% - 0
2
m%)) – 1] x 100%
CO
2
% = [(20.9 - O
2
m) x K2 / 20.9]
Unburned
fuel Loss %
= K4 x CO / ( CO + CO
2
) Note: CO scaled in %
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
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.
Oxygen Reference CO(n) = CO x (20.9 - O
2
r)
(20.9 - O
2
m)