19
Figure 7: IFGR piping specs
4.4.2 Monitor the flue NO
X
content exiting the boiler stack. Wait several minutes after each adjustment to
ensure that sufficient time has elapsed for the flue analyzer to respond to the change and the NO
X
readings are below those required by job specifications.
4.4.3 During and after each adjustment, monitor the boiler and burner for combustion stability and check flue O
2
and CO content. If excessive combustion rumble is present or if CO levels exceed acceptable limits,
reduce the IFGR control damper to the previous position.
4.4.4 Combustion problems are generally caused by too much IFGR volumetric flow. If stack flue gas pressures
are high, typically above +0.1" W.C., a reducing orifice may be required in the IFGR piping to restrict
excessive flow. Consult Power Flame if this circumstance is encountered.
4.4.5 Typical IFGR percentages range from 20% to 30% on a sub 9 PPM NO
X
system. Higher IFGR
percentages can lead to flame instability.
4
4
.
.
5
5
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D
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4.5.1 There are two commonly used methods for determining the IFGR volumetric flow rate (% IFGR).
4.5.2 The first method requires the use of an oxygen analyzer to measure the excess oxygen level in the flue
gas and the oxygen level of the combustion air/flue gas mixture in the burner air housing. The second
reading (burner air housing) may be obtained by inserting the analyzer probe through the burner
observation port or by drilling a small hole and inserting the probe near the discharge of the air housing.
Summary of Contents for UCM-1000
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