CleaverBrooks FLX 700 - Startup, Operating, and Shutdown - All Fuels

Chapter 5 STARTING AND OPERATING INSTRUCTIONS
5-18 750-177
NOTE: It is unnecessary to readjust the
position of the high-fire or low-fire shutters
after having been set for oil firing.
16. Modulate the burner to low fire. The butterfly valve
should be adjusted to provide the correct fuel pressure at
the low-fire position in accordance with the burner data
plate minimum gas-pressure rating.
FUEL FLOW ADJUSTMENTS. Fuel flow rates are adjusted
to provide the design-rated heat inputs into the burner at both
high-fire (maximum rate) and low-fire (minimum rate) oper
-
ating conditions. The maximum and minimum fuel input flow
rates for the burner are identified on the data plate (see Figure
5-8). Natural gas flow rates are specified in cfh (cubic feet per
hour), and fuel oil flow rates are specified in gph (gallons per
hour).
Fuel flow rate adjustment for both natural gas and oil is
accomplished by regulating the fuel pressure against a fixed
diameter orifice (nozzle). The methods for accomplishing the
pressure regulation, however, are different for natural gas and
oil.
The method for regulating the natural gas flow rate (manifold
pressure) is as follows:
1. Maximum flow rate is established by operating the
burner at high-fire with the butterfly valve fully open,
then adjusting the manifold pressure to the maximum as
specified on the data plate. Maximum manifold pressure
is obtained by adjusting the main gas pressure regulator
on the gas train while operating the burner at high-fire.
2. Gas flow modulation for turndown is accomplished by
throttling the flow rate with the butterfly valve. The flow
restriction of the partially closed butterfly valve reduces
the flow of gas through the burner nozzle. The butterfly
valve throttling position is controlled by linkage from the
main air shutter shaft, which is operated by the
modulating motor.
With the modulating motor positioned for low-fire operation,
the butterfly valve linkage is adjusted to provide the
minimum pressure in the nozzle manifold, as specified on the
burner data plate.
INPUT
(
MMBtu/hr
)
max. min. max. min.
10 71.4 23.8 200 82
11 78.6 26.2 185 50
12 85.7 28.6 200 40
Note: Oil pressure is return oil pressure and based on 300 psi pump pressure
FLOW RATE
(
GPH
)
OIL PRESSURE
(
PSI
)
SIZE 4 BURNERS
Table 5-3: Size 4 Burner Pressure and Flow