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Section D - Fuel and Electrical Systems
JBE(X) Manual
The oil pump is supplied as a separate assembly that
includes the pump, backpressure regulator, motor,
coupling, interconnecting housing and motor (FigureB-13).
An optional gauge may also be provided. The motor
starter for the pump is included in the control panel.
The safety shutoff valves determine if the burner is al-
lowed to fire on oil, as controlled by the flame safeguard
system. These valves are the solenoid type except units
over 89 GHP with FM or IRI insurance, where the valves
are motorized with POC (Proof of Closure) switches to
prove closed position prior to allowing the unit to operate.
The low oil pressure switch is used to prove sufficient
oil supply to the burner. It is adjusted to a pressure that
is below the minimum pressure expected at that
location in the system. Two check valves are provided
in the system downstream of the nozzles to prevent the
possible reverse flow of oil from the return line. One
valve is located in the oil gun and the other is located
on the burner piping.
A strainer, manual valve and second check valve should
be installed in the field piping to allow proper operation of
the system (Figure D-3).
4. Air Atomizing #2 Oil
An air atomizing system uses compressed air to atomize
the oil. The oil pump and oil pressure regulating valve
are optional and may be provided by others.
Figure D-4 shows a schematic of the air atomizing #2 oil
system. The oil nozzle has two inputs, oil and air. Oil is
supplied to the system at 125 PSIG. An optional remote
pump assembly may be used, or it can be provided by
other systems. In either case, a backpressure regulator is
required to provide a constant pressure to the system.
The oil metering valve regulates the flow of oil to the
nozzle and is used to vary the oil flow rate from low to
high fire. Modulation is obtained by a fuel cam (linkage
system) or by a direct drive actuator.
An air compressor is used to supply air for atomization.
The air compressor is provided as a separate assembly
and is field piped to the burner. The compressor should
be located as close as possible to the burner to prevent
loss of airflow. Also, the piping should be done to mini-
mize the use of elbows and turns that result in pressure
loss. The following chart should be used to determine the
minimum size (Figure D-5).
Figure D-5 Atomizing Air Line Min. Pipe Size
Piping Length (feet)
Boiler HP
0 - 100 feet
100 - 200 feet
200 - 350
1 inch
1 1/4 inch
400 - 600
1 1/2 inch
2 inch
600 - 1200
1 1/2 inch
2 inch
The atomizing airflow rate is regulated by the bleed
valve, which can bleed off the excess air not required for
good atomization. In some systems, especially with lower
turndown rates, the bleed valve is set manually and does
not vary. In other systems with higher turndowns, the
bleed valve is modulated with firing rate, by connection to
the jackshaft or by a direct drive actuator.
5. Fuel-Air-Ratio Controls
All JBE(X) burners are full modulation. That means that
they can modulate from a lower input to a higher input,
based on a measured need for more or less input. The
system that adjusts the fuel and air flow is called fuel-air-
ratio controls and is covered in this section.
For proper operation, the rate of fuel and air flow must be
closely matched for clean and efficient combustion. Too
little combustion air and not all of the fuel will be burned,
wasting fuel and increasing emissions. Too much air and
the energy is wasted in heating this excess air to a rela-
tively high stack temperature.
There are two common types of fuel-air-ratio controls,
single point positioning (linkage) and parallel position-
ing (linkageless). The linkage system uses mechanical
shafts and connection links to physically tie the air and
fuel control valves together. A modulating motor is used
to modulate the valves from low to high fire by providing
a 90 degree rotation that matches the firing rate required.
A long shaft, called the jackshaft is used to distribute
this 90 degree rotation to each valve. Linkage arms are
connected from the jackshaft to the valve. By adjusting
the positioning of the linkage, the air and fuel valves can
be set to match each other. A fuel cam is used to provide
some improved flexibility in adjusting the intermediate
fuel rates, to match the air damper settings. If the unit
has FGR, the FGR control valve will be tied together with
other valves to provide the correct flow at each firing rate.
The linkageless system uses independent electric
actuators for each fuel, air and FGR valve. These are
driven by a controller, which is programmed to set the
correct position of each valve at multiple firing rates. The
linkageless system offers more flexibility in adjusting the
valves, including low and high fire positions and different
FGR rates for each fuel.
An optional multiple position modulation motor (Figure
E-3) can be used on a linkage system to provide different
low and high fire settings for the different fuels, expand-
ing the turndown capabilities of individual fuels.
6. Electrical Controls
The burner is provided with a control panel or an optional
junction box and free standing control panel. The unit
specific wiring diagram shows the wiring details of all
these components, including the interconnecting wiring
that may be required in the field. The motor starters for
the oil pump and air compressor (if provided) are also
included inside the control panel.
In some cases, the burner wiring diagram shows the
interconnection of all the vessel safety and operating
controls, like the low water cutoff. In other cases, these
are shown on a separate diagram supplied by the vessel
