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5.11.4 Gas pressure
Tab. J indicates the minimum pressure drops along the gas sup-
ply line, depending on the maximum burner output.
The values shown in Tab. J refer to:
–
Natural gas G 20 NCV 9.45 kWh/Sm
–
Natural gas G 25 NCV 8.13 kWh/Sm
Column 1
Combustion head pressure drop.
Gas pressure measured at the test point P1)(Fig. 26), with:
•
Combustion chamber at 0 mbar;
•
Burner working at maximum output;
•
Combustion head adjusted as in page 25.
Column 2
Pressure loss at gas butterfly valve 14)(Fig. 4 on page 12) 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)(Fig. 26).
–
Find, in the table Tab. J related to the burner concerned, the
pressure value closest to the result of the subtraction.
–
Read the corresponding output on the left.
Example RS 410/E BLU with G20 natural gas:
Maximum output operation
Gas pressure at test point P1)(Fig. 26)
Pressure in combustion chamber
58.1 - 5
A pressure of 53.1 mbar, column 1, corresponds in the table Tab.
J to an output of 4450 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)(Fig. 26),
set the MAX output required from the burner operation:
–
find the nearest output value in the table Tab. J for the burner
in question.
–
Read, on the right (column 1), the pressure at the test point
P1)(Fig. 26).
–
Add this value to the estimated pressure in the combustion
chamber.
Example for RS410/E BLU with G20 natural gas:
Required burner maximum output operation: 4450 kW
Gas pressure at an output of 4450 kW
Pressure in combustion chamber
53.1 + 5
Pressure required at test point P1)(Fig. 26).
20107195
Installation
3
3
(8.2 Mcal/Sm
)
3
3
(7.0 Mcal/Sm
)
= 58.1 mbar
=
5 mbar
= 53.1 mbar
= 53.1 mbar
=
5 mbar
= 58.1 mbar
28
GB
1 p (mbar)
kW
G 20
1200
23.1
1440
23.6
1690
24.1
1930
24.6
2170
25.1
2420
26.7
2660
29.6
2900
33.4
3140
38
3390
43.7
3630
50.1
1500
2.6
1800
7.1
2090
11.5
2380
16.1
2680
21.1
2980
26.1
3270
31.2
3560
36.3
3860
41.9
4160
47.5
4450
53.1
1800
14.0
2140
15.5
2490
17.8
2840
20.7
3180
24.2
3520
28.3
3870
33.3
4220
39.0
4560
45.2
4900
52.0
5250
59.7
2200
9.3
2600
13.6
3010
18.6
3420
24.1
3820
30.1
4220
36.5
4630
43.7
5040
51.5
The data of thermal output and combustion
head gas pressure are related to full open (90°)
gas butterfly valve.
WARNING
2 p (mbar)
G 25
G 20
G 25
34.5
0.1
0.1
35.2
0.5
0.7
36.0
1.1
1.6
36.7
2.1
3.1
37.4
3.1
4.6
39.8
4.2
6.3
44.2
5.3
7.9
49.8
6.4
9.5
56.7
7.6
11.3
65.2
8.8
13.1
74.7
10
14.9
3.9
0.3
0.5
10.6
1.5
2.2
17.2
2.8
4.2
24.0
4.0
6.0
31.5
5.4
8.1
38.9
6.8
10.1
46.6
8.2
12.2
54.2
9.6
14.3
62.5
11.2
16.7
70.9
12.7
18.9
79.2
14.3
21.3
20.9
1.5
2.2
23.1
3.0
4.5
26.6
4.5
6.7
30.9
6.1
9.1
36.1
7.8
11.6
42.2
9.4
14.0
49.7
11.2
16.7
58.2
13.0
19.4
67.4
14.9
22.2
77.6
16.8
25.1
89.1
18.8
28.0
13.9
3.3
4.9
20.3
5.0
7.5
27.8
7.0
10.4
36.0
8.9
13.3
44.9
11.0
16.4
54.5
13.0
19.4
65.2
15.3
22.8
76.8
17.6
26.3
Tab. J
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