baltur GI 1000 DSPN-D, Instructions Manual

Page: 43 / 76

43
ENGLISH
DESCRIPTION OF OPERATION WITH HEAVY OIL
(See 0002900311)
Turn the main isolating switch “Q1” to on: the power indicator light will come on, as will the auxiliary elements of the
pump, filter, atomising unit and regulating valve (.....N-D version only).
Turn the start/stop switch “S1” to on: power reaches the “LFL...” control box at terminal “1” and the preheater regu-
lation thermostats. The voltage crosses the thermostat contacts and reaches the “KR1” and “KR2” element contac-
tor coils which come on and heat the fuel contained in the preheaters.
The preheater minimum thermostats come on when the temperature reaches the value to which they are set, thus
turning on the control box via the pressure switch line.
The cyclic relay control box carries out the ignition programme by running the fan motor to effect pre-ventilation.
If the air pressure supplied by the fan is sufficient to trip the relative pressure switch then the motor of the pump
which pre-circulates the hot air in the burner conduits starts immediately.
The oil flows from pump to preheater, passes through the latter, heats up to the set temperature and exits via a filter
where it then reaches the atomising unit. The hot oil circulates in the atomising unit without exiting the nozzle
because the passageways towards the nozzle (delivery) and from the nozzle (return) are closed. Closure is effected
by means of the “closing cones” applied to the rod extremities.
These “cones” are pressed against the seats by strong springs fitted at the opposite end of the rods. The oil circu-
lates and exits from the atomising unit return via the sump where the TRU thermostat is inserted. It then arrives at
the return pressure regulator, passes through it and reaches the pump return. From this, it is discharged into the
return. The above-described hot oil circuit is effected at a pressure slightly higher (a few atmospheres higher) than
the minimum to which the return pressure regulator is set (10 - 12 bar).
This oil pre-ventilation stage lasts 22.5 seconds. This time can be extended (in theory, indefinitely) because the
design of the electrical circuit does not allow the ignition programme to proceed until the fuel in the nozzle return
piping has reached the temperature to which the TRU (Thermostat on Nozzle Return) is set.
This special design feature stops the fuel passing through the nozzle until the fuel itself reaches at least the tem-
perature to which the TRU thermostat is set. The TRU thermostat usually trips within the standard pre-ventilation
time (37.5 seconds); if it does not, heavy oil pre-ventilation and pre-circulation are extended until the TRU trips.
When the TRU trips (circulating oil hot enough) it allows the control box to proceed with the ignition programme by
switching on the ignition transformer and then the gas pilot flame valves.
The high voltage between the burner electrode and its ground causes the spark which ignites the gas/air mix. Flow
is regulated by the flow-rate regulator incorporated in one of the two pilot flame valves. The flame is detected by the
UV photocell.
Note: 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 the atomising unit; consequently, the in-pump pres-
sure is brought to the standard value of about 20 - 22 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.
Safety time
in seconds
2.5
Pre-ventilation and
pre-circulation time
in seconds
37.5
Pre-ignition
in seconds
5
Post-ignition
in seconds
2.5
Time between 1st
(pilot) flame and start
of modulation
in seconds
12.5
Control box
and
programmer
LFL 1.335
Cyclic relay
CONTROL BOX CHARACTERISTICS