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5.11.4 Gas pressure
Tab. K indicates the minimum pressure drops along the gas sup-
ply line, depending on the maximum burner output.
The values shown in Tab. K 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. 25), with:
•
Combustion chamber at 0 mbar;
•
Burner working at maximum output;
•
Combustion head adjusted as in page 22.
Column 2
Pressure loss at gas butterfly valve 4)(Fig. 31 on page 30) 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. 25).
–
Find, in the table Tab. K 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/M MZ with natural gas G20:
Maximum output operation
Gas pressure at test point P1)(Fig. 25)
Pressure in combustion chamber
46.7 - 5
A pressure of 41.7 mbar, column 1, corresponds in Tab. K to an
output of 4900 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. 25),
set the MAX output required from the burner operation:
–
find the nearest output value in the table Tab. K for the burner
in question.
–
read, on the right (column 1), the pressure at the test point
P1)(Fig. 25).
–
Add this value to the estimated pressure in the combustion
chamber.
Example RS 410/M MZ with natural gas G20:
Required burner maximum output operation: 4900 kW
Gas pressure at an output of 4900 kW
Pressure in combustion chamber
41.7 + 5
Pressure required at test point P1)(Fig. 25).
20080128
Installation
3
3
(8.2 Mcal/Sm
)
3
3
(7.0 Mcal/Sm
)
= 46.7 mbar
=
5 mbar
= 41.7 mbar
= 41.7 mbar
=
5 mbar
= 46.5 mbar
26
GB
1 ∆ p (mbar)
kW
G 20
G 25
1300
3.4
5.1
1560
5.5
8.2
1820
7.8
11.6
2080
10.3
15.4
2340
13.0
19.4
2600
15.9
23.7
2860
18.9
28.2
3120
22.2
33.1
3380
25.7
38.3
3640
29.3
43.7
3900
33.2
49.5
2000
13.8
20.6
2290
14.5
21.6
2580
15.7
23.4
2870
17.4
26.0
3160
19.5
29.1
3450
22.1
33.0
3740
25.1
37.4
4030
28.6
42.7
4320
32.5
48.5
4610
36.9
55.1
4900
41.7
62.2
2200
15.7
23.4
2540
16.3
24.3
2880
17.4
26.0
3220
19.2
28.6
3560
21.6
32.2
3900
24.6
36.7
4240
28.2
42.1
4580
32.5
48.5
4920
37.3
55.7
5260
42.8
63.9
5600
48.9
73.0
2400
10.3
15.4
2790
13.8
20.6
3180
17.8
26.6
3570
22.2
33.1
3960
27.0
40.3
4350
32.2
48.0
4740
37.9
56.5
5130
43.9
65.5
5520
50.4
75.2
5910
57.3
85.5
6300
64.6
96.4
2 ∆ p (mbar)
G 20
G 25
0.1
0.1
0.5
0.7
1.6
2.4
2.7
4.0
3.9
5.8
5.0
7.5
6.2
9.3
7.5
11.2
8.7
13.0
10.0
14.9
11.4
17.0
2.4
3.6
3.6
5.4
4.9
7.3
6.3
9.4
7.7
11.5
9.1
13.6
10.5
15.7
12.0
17.9
13.6
20.3
15.1
22.5
16.8
25.1
3.3
4.9
4.8
7.2
6.3
9.4
8.0
11.9
9.6
14.3
11.4
17.0
13.1
19.5
15.0
22.4
16.9
25.2
18.8
28.0
20.8
31.0
4.1
6.1
5.9
8.8
7.8
11.6
9.7
14.5
11.7
17.5
13.7
20.4
15.9
23.7
18.1
27.0
20.3
30.3
22.7
33.9
25.1
37.4
Tab. K
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