CleaverBrooks CBEX Elite, Эксплуатация и обслуживание

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750-368
CBEX Elite 100-1200 HP 2-9
2.10 — Gas Fuel Flow
Fuel oil is delivered into the system by a supply pump which delivers part of its discharge to the oil burner.
Excess oil is returned to the oil storage tank through the fuel oil relief valve and oil return line. Normally, the
pump operates only while the burner is in operation, although a positioning switch is often provided so that either
continuous or automatic pump operation can be obtained.
The oil flows through a fuel oil strainer to prevent any foreign material from flowing through the control valves
and nozzle. The fuel oil controller contains in a single unit a metering valve, a regulator, and a gauge required to
regulate the pressure and flow of oil to the burner. The adjustable regulator controls the pressure. To assist in the
regulations, back pressure is created by an orifice nozzle located in the oil return line immediately downstream of
the fuel oil controller.
The programming relay energizes or de-energizes the solenoid oil valves to permit or cut off oil flow to the burner.
Two valves, operating simultaneously, are used. The valves are closed when de-energized. They cannot be
opened (energized) unless the combustion air proving switch and the atomizing air proving switch are closed.
The two switches are satisfied, respectively, by sufficient combustion air pressure from the forced draft fan and
pressurized air from the air pump.
The oil flow to the burner is controlled by the movement of the metering stem in the oil metering valve, which
varies the flow to meet load demands. The metering valve and the air damper are controlled simultaneously at all
times by independent actuators to proportion combustion air and fuel for changes in load demand.
2.10 — Gas Fuel Flow
Metered gas from the utility flows through the pressure regulator at a reduced pressure suitable to burner require-
ments, through the main gas shutoff cock, main gas valve(s), and modulating butterfly gas valve to the nonpre-
mix orifice-type burner.
The main gas valve is of the normally closed type, and is opened (energized) in proper sequence by the program-
ming relay.
The butterfly gas valve modulates the flow of gas from low through high fire settings. The position of the butterfly
valve disc is governed by the gas valve actuator. The butterfly gas valve and the air control damper are controlled
simultaneously by independent actuators to proportion combustion air and fuel for changes in load demand.
The gas flow rate required for rated burner input depends upon the heating valve (Btu/cubic foot) of the gas sup-
plied. The gas pressure regulator adjusts the gas pressure (flow rate) to the entrance of the gas train. The regula-
tor is not always supplied with the burner, but may be provided by others.
The main gas valves cannot be energized (opened) unless the combustion air proving switch is closed to indicate
a sufficient supply of combustion air. The low gas pressure and high gas pressure switches must be closed to
prove sufficient, but not excessive, gas fuel pressure.
2.11 — Modulating Firing
A combustion curve for each fuel is programmed into the Hawk controls during boiler commissioning. The com-
bustion curve settings will determine how the butterfly gas valve (or the oil metering valve), air damper, and FGR