Chapter 2 Profire V Burner
2-42 750-177
L. Air and Fuel Controls
A
IR SHUTTER
REAR
AIR SHUTTER
Figure 2-27: Air Shutters
The V series burners have a two-blade air shutter
design. Both blades are coupled together and are
attached to the modulation motor. Changing the
positions of the linkage rods on the linkage control
arms will change the way the damper blades open
and close.
Fuel and air flow rates can be individually adjusted at
low-fire and high-fire to ac
hieve rated heat input,
firing rate turndown, optimum efficiency, safe
operation, and the ability to cope with environmental
changes (air temperature, humidity, barometric
pressure), and fuel property changes. Adjustments
may be required to meet certain environmental
emissions criteria, such as NOx or CO. Combustion
adjustments also vary with specific system
applications.
Turndown capability for oil is less than that of natural
ga
s. On combination fueled burners, gas turndown
performance may be restricted by the excess air and
fuel turndown levels set for oil combustion.
Excess air (O2) and unburned fuel (CO) levels
in
boiler flue gases are used to determine
combustionefficiency and fuel and air input
adjustments. The system should be adjusted to a
minimum excess airquantity that provides low levels
of unburned fuel with sufficient remaining O2 to cope
with normal atmospheric and fuel related changes.
Unburned fuel is measured as CO when burning
natural gas, and smoke spots when burning oil.
The burner should be set up and maintained to yield
sm
oke spot levels less than No. 1 spot (ASTM
D2156 Shell Bacharach Scale) to minimize soot and
buildup in the boiler.
Keep fingers away from the air inlet area of the
damper. The damper is actuated with sufficient force
to cause severe injury.
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