Table of Contents
Advertisement
7.6
Combustion head
The combustion head comprises a highly heat resistant cylinder
whose surface features numerous holes, encased in a metal
"mesh".
The air-gas mixture is pushed inside the cylinder and out of the
head through the holes in the perimeter.
Combustion begins with ignition of the air/gas mixture that comes
out of the pilot system by means of the electrode spark.
After the stabilization of the pilot flame (approx. 3 seconds), the
main valve opens up and, after approx. 7 seconds, the pilot flame
goes out while the main one stays on.
The metal "mesh" is the combustion head's most essential ele-
ment since it improves burner performance considerably.
The flame developed on the surface of the head is perfectly re-
tained and adheres to the mesh when operating at the maximum
setting.
7.7
Burner adjustment
The optimum adjustment of the burner requires an analysis of
flue gases at the generator outlet.
The burner application at the generator, the adjustment and the
testing must be carried out in compliance with the instruction
manual of the generator itself, including the control of the concen-
tration of CO and CO
in the flue gases and of their temperature.
2
Check in sequence:
–
MAX output
–
MIN output
The MAX output should be equal to the value requested by the
boiler used. To increase or decrease its value use the external
modulation control.
Measure the gas delivery on the counter to precisely establish the
burnt output.
Using a smoke analyser, measure the value of the CO
in order to optimise the burner calibration.
The correct values are: CO
To correct these values act on the gas valve in the following way:
to increase the gas delivery and the CO
"+" sign (Fig. 21);
to reduce the gas delivery and the CO
sign (Fig. 21).
The MIN output should be equal to the value requested by the
boiler used. To increase or decrease its value use the external
modulation control.
Measure the gas delivery on the counter to precisely establish the
burnt output (to be adjusted depending on gas pressure).
Using a smoke analyser, measure the value of the CO
in order to optimise the burner calibration.
The correct values are: CO
To correct these values act on the gas valve in the following way:
to increase the gas delivery and the CO
"+" sign;
to reduce the gas delivery and the CO
sign.
20160576
Start-up, calibration and operation of the burner
2
8.2 - 9% (for methane).
2
: turn the V1 to the
2
: turn the V1 to the "-"
2
2
7.8 - 8.5% (for methane).
2
: turn the V2 to the
2
: turn the V2 to the "-"
2
This allows modulating ratios as high as 6:1, avoiding the danger
of flashback when modulating is at its minimum.
The flame features an extremely compact geometry, meaning
that there is no risk of contact between the flame and parts of the
generator, consequently eliminating the possible problem of poor
combustion.
The flame's structure means that smaller combustion chambers
can be developed, designed to exploit this particular feature.
CAUTION
7.7.1
Indicative calibration values
Methane
LPG
G25
or the O
2
D9714
7.7.2
Emissions
The emission values (in accordance with EN 676) of the burners
are much lower than the limits laid down by the strictest stand-
ards.
The flame's distribution and its spread over a large surface
means that the burner manages to limit the formation of thermal
NOx, the main causes of pollutant emission.
or the O
2
52
GB
Before starting up the burner, it is good practice to
adjust the gas train so that ignition takes place in
conditions of maximum safety, i.e. with gas deliv-
ery at the minimum.
MIN output
CO
(%)
O
(%)
CO
2
2
8
6.6
9.5
6.4
7.8
6.8
MAX output
(%)
O
(%)
2
2
8.5
5.7
10
5.6
8.3
5.8
Tab. P
Fig. 164
Advertisement
Table of Contents
