Description Of Operation With Light Oil - baltur GI MIST 1000 DSPGM Manual De Instrucciones

DESCRIPTION OF OPERATION WITH LIGHT OIL

(S 0002900311)
EE
Turn the main isolating switch "Q1" to on: the power indicator light
will come on. Turn the start / stop switch "S1" to on: power reaches
the "LFL ..." control box at terminal "1" and the preheter regulations
thermostat. The cyclical relay equipment carries out its ignition
program, starting up the fan motor for a pre-ventilation stage.
If the air pressure provided by the fan is sufficient to cause the
corresponding pressure switch to intervene, it does so immediately,
and so also the motor for the pump that sends the light oil to the
burner ducts.
From the light oil pump the fuel goes to the atomisation unit and cir-
culates in this without coming out as the way to the nozzle (delivery)
and from the nozzle (return) are closed. This closure is by means of
the "closing pins" at the end of the rods. These "pins" are pressed
against the housing by strong springs at the other end of the rods.
The light oil circulates and flows out from the atomisation unit's
return to come to the return pressure regulator, goes through this
and then reaches the pump return and from this is discharged into
the return. The above light oil circulation takes place at a pressure
that is a few bar higher than the minimum pressure setting for the
return pressure regulator (10 ÷ 12 bar). The light oil's pre-ventilation
and pre-circulation stage duration is not that provided for by the
equipment because it is carried out with the air damper in its open
position. The pre-ventilation and pre-circulation time is thus the sum
of the times of the following manoeuvres:
- fuel/air supply servo motor opening stroke +
- pre-ventilation time required by the equipment +
- closing stroke of fuel/air supply adjustment servo motor up to
ignition air position.
The equipment subsequently goes through its ignition program
inserting the ignition transformer and then the pilot light valves. The
high tension between the electrode and the burner mass causes
the electrical discharge (spark) that ignites the gas/air mixture.
The supply is adjusted by the flow adjuster incorporated in one of
the two pilot light valves. The flame's presence is detected by the
photoelectric UV cell.
If the UV photocell does not detect the flame then the burner
!
locks out. When more than one burner is operating in the
combustion chamber, you must make sure that the UV
photocell of one burner does not detect the flame of the
other. This is prevented by installing the photocell on a
rotatable support so that it can be positioned to avoid the
above-described interference.
Just 2.5 seconds after the ignition of the pilot flame, the control box
powers the magnet which, via a series of lever mechanisms, moves
the two nozzle fuel flow (delivery and return) interception rods.
The moving of these rods causes closure of the by-pass inside
Control box Safety time
and
programmer in seconds
LFL 1.335 Cyclic relay
CONTROL BOX CHARACTERISTICS
Pre-ventilation and
pre-circulation time
in seconds
2.5 37.5
0006080764_201006
the atomising unit; consequently, the in-pump pressure is brought
to the standard value of about 18 - 20 bar. The shifting of the two
rods from the closure seats now lets the fuel flow into the nozzle
at a pump-regulated pressure of 20 - 22 bar and exit the nozzle
properly atomised. The return pressure, which determines the flow
in the chamber, is adjusted by the return pressure regulator. For
ignition flow rate (minimum delivery) this value is about 10 - 12 bar.
The atomised fuel which exits the nozzle mixes with the fan-fed air
and is ignited by the already-lit gas pilot flame. After the magnet is
switched on the pilot flame is switched off and the burner is run at
the modulation minimum. Flow increase occurs automatically and
continuously according to the signals from the modulation probe:
increase is effected by means of a servomotor.
The modulation motor controls a simultaneous increase in the flow
of both fuel and combustion air. The increase in the flow of fuel is
determined by the variable-profile disk which, by rotating, causes
greater compression of the return pressure regulator spring and
thus an increase in return pressure corresponds to an increase in
fuel flow. An increase in fuel flow must correspond to an increase
(of adequate quantity) of combustion air. This condition is brought
about during the first adjustment by acting on the screws that vary
the combustion air adjuster control disk profile. Fuel flow and, at the
same time, combustion air flow, increase up to maximum pressure
(fuel pressure at return pressure regulator of about 18 - 20 bar) if
pressure at the pump is 20 - 22 bar.
Fuel and combustion air flow rates remain at maximum until boiler
temperature (pressure in the case of a steam boiler) nears the set
value and causes the modulation control motor to invert rotation.
The return movement of the modulation motor causes a reduction
in the flow of fuel and relative combustion air.
The modulation system reaches a position of equilibrium which
corresponds to a flow of fuel and relative combustion air equal to
the quantity of heat requested by the boiler. With the burner working
the in-boiler probe detects variations in boiler load and automatically
sends a signal to the modulation motor to adjust the flow of fuel and
relative combustion air accordingly. If, even with just the minimum
flow of fuel and combustion air, the maximum temperature (or
pressure in the case of a steam boiler) is reached, the thermostat
(pressure switch in the case of a steam boiler) will shut down the
burner completely. Subsequently, the temperature (or pressure in
the case of a steam boiler) will drop back below the shutdown setting
and the burner will re-ignite as described above.
Bear in mind that the possible flow range, with good combustion, is
approximately from 1 to 1/3 of the max flow rate indicated on the ID
plate. Should the flame fail to appear within two seconds of the pilot
flame igniting, the control box places the unit in "lock-out" (complete
shutdown of burner with relative warning light).
To "reset" the control box press the appropriate reset button.
The air pressure switch must be adjusted on igniting the burner
!
as a function of the pressure value observed for operation
with the pilot flame.
Pre-ignition Post-ignition
in seconds in seconds
5 2.5
9 / 32
Time between 1st (pilot)
flame and start of modula-
tion in seconds
12.5
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