19
20098208
GB
Installation
5.11.3
Gas train installation
The gas train is prearranged to be connected on the right of the
burner, by the flange 1)(Fig. 22).
If it is necessary to connect it on the left of the burner, undo the
nuts and screws 3) and 4), remove the blind flange 2) and the rel-
ative gasket and apply them to the flange 1), tightening the nuts
and screws again.
5.11.4
Gas pressure
Tab. H indicates the minimum pressure drops along the gas sup-
ply line, depending on the maximum burner output.
The values shown in Tab. H refer to:
–
Natural gas G 20 NCV 9.45 kWh/Sm
3
(8.2 Mcal/Sm
3
)
–
Natural gas G 25 NCV 8.13 kWh/Sm
3
(7.0 Mcal/Sm
3
)
Column 1
Pressure drop on combustion head.
Gas pressure measured at the test point P1)(Fig. 22), with:
•
Combustion chamber at 0 mbar;
•
Burner working at maximum output;
•
Combustion head adjusted as in page 17.
Column 2
Pressure loss at gas butterfly valve with maximum opening: 90°.
Calculate the approximate maximum output of the burner in this
way:
–
subtract the combustion chamber pressure from the gas
pressure measured at test point P1).
–
Find, in the table Tab. H related to the burner concerned, the
pressure value closest to the result of the subtraction.
–
read the corresponding output on the left.
Tab. H
Example with G20:
Maximum output operation
Gas pressure at test point P1)
=
19 mbar
Pressure in combustion chamber
=
4 mbar
19 - 4
=
15 mbar
A pressure of 15 mbar, column 1, corresponds in the table Tab.
H to an output of 3000 kW.
This value serves as a rough guide; the effective output must be
measured at the gas meter.
To calculate the required gas pressure at test point P1), set the
MAX output required from the burner operation:
–
find the nearest output value in the table Tab. H for the burner
in question.
–
read, on the right (column 1), the pressure at the test point
P1).
–
Add this value to the estimated pressure in the combustion
chamber.
Example with G20:
Required burner maximum output operation
Gas pressure at an output of 3000 kW
=
15 mbar
Pressure in combustion chamber
=
4 mbar
15 + 4
=
19 mbar
pressure required at test point P1).
DANGER
Disconnect the electrical power using the main
system switch.
Check that there are no gas leaks.
Beware of train movements: danger of crushing of
limbs.
Make sure that the gas train is properly installed
by checking for any fuel leaks.
The operator must use appropriate tools for instal-
lation.
kW
1
∆
p (mbar)
2
∆
p (mbar)
G 20
G 25
G 20
G 25
1245
7.8
11.6
1.3
2.0
1500
9.4
13.9
1.9
2.8
1750
10.9
16.2
2.6
3.9
2000
12.4
18.5
3.4
5.0
2250
13.0
19.5
4.3
6.4
2500
13.7
20.4
5.3
7.9
2750
14.3
21.4
6.4
9.5
3000
15.0
22.4
7.6
11.3
3250
17.6
26.2
8.9
13.3
3500
20.2
30.1
10.3
15.4
3800
23.3
34.8
12.2
18.2
20061420
Fig. 22