illiiilli
AALBORG
INDUSTRIES
BURNER OPERATION OM5560_98#A.2
Burner operation
1
Language
UK
General
This section describes the burner operation. Figure I illustrates the internal oil piping
at the burner;Figure 2showsthe oil flow in different burner modes. Finally Figure 3
illustrates the nozzle valve.
1.1
Start sequence for burners with microprocessor control sys-
terns
Pre-purge takes place with the air quantity
of
full load. During pre-purge period sole-
noid valves (4), (5), and (8)are closed and solenoid valve (15) is open, see Figure I
and Figure 2.
At
the end
of
the purging period the servomotors
tum
to the position
of
ignition load and solenoid valve (5) and (8) open and a flushing sequence will take
place, the nozzle valve is purged (pre-heated) during this period. The oil temperature
regulation controls that the oil temperature is adequate during purging and atomising
periods.
After the flushing period is completed the solenoid valve (5) will close and the oil in
the pre-heater will be heated. The burner will then go into the ignition step; solenoid
valves
(4) and (5)areopened and solenoid valve (3) closes, the oil pressure begins to
take effect on the nozzle control circuit. Oil flows from the nozzle. The force
of
the oil
pressure on the piston must exceed the force
of
the spring. The electric arc between the
ignition electrodes ignites the oil spraying from the nozzle.
1.2 Burner operation
The oil quantity to be fired is regulated by means
of
the oil regulator (12) by throttling
the return flow.
At
partial load the oil regulator is open and at full load closed.During
burner operation the control system drives the servomotors, which again drives the oil
regulator and the air dampers between partial load and full load according to the steam
demand.
If
the burner shuts down, solenoid valves (4), (5), and (8) close, and solenoid
valve (3) opens. The oil pressure is released from the nozzle valve.
The nozzle valve spring-back closes the needle valve in the nozzle and closes the oil
flow in the nozzle. At full
load the atomising pressure is approx. 20-25 bar when
operating on diesel oil and approx. 25-30 bar on heavy fuel oil. The return flow pressure
in the oil regulator (12) in ignition position is approx. 7-10 bar and at partial load
9-) 2
bar. The return flow pressure
is
determined according to the position
of
the oil regu-
lator.
21-37/6Q
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