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4.2.1 NO
X
is the shorthand common name of two Nitrogen Oxides: NO and NO
2
. The NO
X
is a pollutant and
constitutes a serious health hazard.
4.2.2 The NO
X
is produced in several ways, the most common of which is the oxidation of the Nitrogen present
in the air (thermal NO
X
). This chemical process is mainly due to the high temperature around the flame.
4.2.3 The IFGR system lowers the flame peak temperature by introducing a certain amount of flue gas together
with the combustion air which leads to a reduction in NO
X
emissions.
4.2.4 The flue gas is introduced in the air inlet and mixed with the combustion air stream. This increased "air
side" mass flow, for a given heat release, provides results very similar to lean combustion but with less
added oxygen to combine with nitrogen to form NO
X
. As mentioned before, the rate of thermal NO
X
formation is primarily temperature dependant, hence lower resultant NO
X
formation is achieved by the
heat absorption effect of the increased mass flow of combustion air/flue gas mixture in the combustion
zone. This increased mass flow results in greater turbulence for the combustion process generally
providing shorter, more compact flame envelopes.
4.2.5 Note: the added mass flow through the system results in a system pressure drop increase. A typical total
of 40% to 60% combustion chamber static pressure increase can be expected on most installations when
operating at the rated capacity of the heat exchanger.
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4.3.1 The IFGR Low NO
X
adapter is pre-mounted to the UCM burner and IFGR pipe sizing recommendations
are included in Figure 7. The IFGR piping is not provided by Power Flame.
4.3.2 Install the IFGR pipe from the stack, or last pass smoke box, to the burner IFGR connecting flange. If the
takeoff is from the stack, it should be upstream of any stack damper or barometric damper. If a barometric
damper is used, care must be taken to ensure that fresh air infiltration into the IFGR system does not
occur. It is recommended that the IFGR pipe extends to the center of the stack and includes a 45
˚
miter
cut facing down into the stack flue gas flow (see Figure 7). Seamless carbon steel pipe or tubing is
recommended for the IFGR pipe.
4.3.3 The IFGR piping should be routed to minimize pipe length and number of fittings. In higher draft
applications, increased pipe sizes from that recommended in Figure 7 may be required.
4.3.4 Induced flue gas piping between the stack and burner should be evaluated for insulation requirements
based on personnel protection requirements, allowable site heat dissipation specifications (if indoors),
and applicable codes. Lower flue gas temperatures enhance IFGR operation. Caution must be taken not
to operate at extended periods or larger number of cycles with IFGR temperatures below 250
˚
F as to
prevent condensation and excessive corrosion.
4.3.5 Install gas supply piping and gas train components per the gas piping diagram supplied with the burner. If
the burner is a combination gas/oil type, install supply and return oil piping, per the manufacturer’s
recommendations, adhering to all governing local and state codes.
4.3.6 Wire gas train components and interconnecting wiring per the wiring diagram supplied with the burner.
IFGR wiring connections are integral to the burner and are pre-wired at the factory.
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4.4.1 For initial system commissioning, it is necessary that the IFGR modulating damper be operated and the
servo positions set with each fuel being commissioned.
Summary of Contents for UCM-1000
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