Burner Firing; Burner Calibration - Riello RL 70/M Installation, Use And Maintenance Instructions

(A)
PRESSURE CONTROLLER
D1227
1 - Manometer for pressure in return line
2 - Oil pressure switch
3 - Ring for piston stop
4 - Nut and lock-nut for piston setting
5 - Eccentric adjusting screw
6 - Variable eccentric
7 - Eccentric locking screws
(B)
(C)
1 2
D791
Return pressure

BURNER FIRING

Close load controls and set switch 1)(A) to
"MAN".
After burner firing a complete burner adjustment
should be performed.

BURNER CALIBRATION

The optimum calibration of the burner requires
an analysis of the flue gases at the boiler outlet.
The following settings that have already been
made do not require modification under normal
circumstances:
• Combustion head;
• Servomotor, cams I - II - IV - V
Contrarily, the settings listed below must be
adjusted in sequence:
1 - MAX burner output;
2 - MIN burner output;
3 - Intermediate outputs between MAX and MIN
output.
1 - MAX output
Max output of the burner must be set within the
firing rate range shown on page 4.
In the above instructions we left the burner run-
ning in MIN output operation. Now press button
2)(A) "+" until servomotor arrives at 130°.
Adjusting the nozzle flow rate
The nozzle flow rate varies according to the fuel
pressure on the nozzle return.
Diagram (C) indicates this relationship for type
A3 and A4 Bergonzo nozzles with pump delivery
pressure of 20 bars.
Diagram (C):
Horizontal axis
Vertical axis
NOTE: with a pump delivery pressure of 20 bar,
the pressure on the nozzle return must not
exceed 17 bars.
The pressure difference between pump delivery
and nozzle return must be at least 3 bars. With
smaller pressure differences, the pressure on
the nozzle return can be unstable.
The nozzle return pressure value is indicated by
the pressure gauge 1)(B).
The output and the pressure of the nozzle are at
maximum when the servomotor is positioned on
130°.
The fine adjustment of the pressure in the return
line may be carried out by changing the setting
of the eccentric 6)(B), of the nut and lock-nut
4)(B).
The eccentric setting should be carried out by
loosening screws 7), and turning the screw 5) to
obtain the desired eccentricity. Turn clockwise
the screw 5) to increase the eccentricity,
increasing the difference between the min. and
max. capacity of the nozzle; turn counter-clock-
wise the screw 5) to decrease the eccentricity
and, consequently the difference between the
min. and max. capacity of the nozzle.
NOTE
• The proper setting of the eccentric 6) is possi-
ble when its operation field follows the servo-
motor operation field (20° ÷ 130°): so, that
every variation of the servomotor position cor-
responds to a pressure variation.
• Do not let the piston beat repeatedly: the stop
ring 3)(B) determines the max. stroke.
• When the setting is carried out (pag. 12), verify
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manually that no slow-down occurs between
0° and 130° and that the maximum and mini-
mum pressures correspond to those chosen
as per diagram (C).
• If you wish to check the delivery capacity of
the nozzle, open the burner, attach the nozzle,
simulate the start-up and then proceed with
weighing of the maximum and minimum pres-
sures of the fuel.
• If at the maximum capacity of the nozzle (max-
imum pressure in the return line) pressure fluc-
tuations are detected on the manometer 1),
slightly decrease the pressure in the return line
until they are completely eliminated.
11
: bar, nozzle return pressure
: kg/h, nozzle flow rate