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5.13.4 Gas pressure
Tab. M indicates the minimum pressure drops along the gas sup-
ply line, depending on the maximum burner output.
The values shown in Tab. M 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. 27), with:
•
Combustion chamber at 0 mbar;
•
Burner working at maximum output;
•
Combustion head adjusted as in page 21.
Column 2
Pressure loss at gas butterfly valve 14)(Fig. 5 on page 14) 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. 27).
–
Find, in the table Tab. M related to the burner concerned, the
pressure value closest to the result of the subtraction.
–
Read the corresponding output on the left.
Example RLS 410/M MX with natural gas G20:
Maximum output operation
Gas pressure at test point P1)(Fig. 27)
Pressure in combustion chamber
29.4 - 5
A pressure of 24.4 mbar, column 1, corresponds in the table Tab.
M 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)(Fig. 27),
set the MAX output required from the burner operation:
–
find the nearest output value in the table Tab. M for the burner
in question.
–
Read, on the right (column 1), the pressure at the test point
P1)(Fig. 27).
–
Add this value to the estimated pressure in the combustion
chamber.
Example RLS 410/M MX with natural gas G20:
Required burner maximum output operation: 3000 kW
Gas pressure at an output of 3000 kW
Pressure in combustion chamber
24.4 + 5
Pressure required at test point P1)(Fig. 27).
Installation
3
3
(8.2 Mcal/Sm
)
3
3
(7.0 Mcal/Sm
)
= 29,4 mbar
=
5 mbar
= 24.4 mbar
= 24.4 mbar
=
5 mbar
= 29.4 mbar
27
GB
1 p (mbar)
kW
G 20
G 25
1200
3.6
5.4
1467
5.4
8.1
1733
7.5
11.2
2000
9.9
14.8
2267
12.7
18.9
2533
15.8
23.6
2800
19.3
28.8
3067
23.1
34.5
3333
27.3
40.7
3600
31.8
47.4
1500
6.4
9.5
1800
9.0
13.4
2100
12.2
18.2
2400
15.8
23.6
2700
19.9
29.7
3000
24.4
36.4
3300
29.4
43.9
3600
34.9
52.1
3900
40.9
61.0
4200
47.3
70.6
1800
7.0
10.4
2174
9.8
14.6
2549
13.0
19.4
2923
16.6
24.8
3298
20.7
30.9
3672
25.2
37.6
4047
30.2
45.1
4421
35.6
53.1
4796
41.5
61.9
5170
47.8
71.3
2200
8.7
13.0
2639
12.5
18.6
3079
17.1
25.5
3518
22.3
33.3
3958
28.2
42.1
4397
34.8
51.9
4837
42.1
62.8
5276
50.1
74.7
5716
58.8
87.7
6155
68.2
101.8
2 p (mbar)
G 20
G 25
0.1
0.1
0.2
0.3
0.4
0.6
0.7
1.0
1.0
1.5
1.3
1.9
1.7
2.5
2.1
3.1
2.6
3.9
3.1
4.6
0
0
0.2
0.3
0.5
0.7
0.8
1.2
1.2
1.8
1.7
2.5
2.3
3.4
2.9
4.3
3.6
5.4
4.4
6.6
1.5
2.2
2.0
3.0
2.6
3.9
3.3
4.9
4.1
6.1
4.9
7.3
5.8
8.7
6.8
10.1
7.8
11.6
9.0
13.4
2.7
4.0
3.9
5.8
5.3
7.9
6.9
10.3
8.7
13.0
10.7
16.0
13.0
19.4
15.4
23.0
18.1
27.0
21.0
31.3
Tab. M
20084880
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