Meter every unit of steam generated



               Meter every unit of steam, generated or distributed.

After generating, steam is distributed to various sections from the main steam pipe/header. But it is necessary to know the exact steam consumption in the individual departments within the production plant or in the individual production lines.

Any indicated increase in steam consumption above the accepted norm for a given production rate will indicate some inefficiency developing in that section of steam using production plant, which can be investigated and remedied. The other perhaps obvious reason for the monitoring of steam consumption is the ability to operate accurate cost accounting for a specific product line.

The steam flow meter is the perfect tool for providing exact information about the steam consumption and steam quality.

Sizing of steam pipes

Steam pipe size may be chosen on the basis of either steam velocity or pressure drop along the pipe length.

                                                 Bore of pipe in mm

Pressure Bar g
Velocity m/s
 15
20
25
32
40
50
65
80
100
125
150
1

15
25
40

8
12
19

17
26
39
29
48
71
43
72 112
65 100 172
112 193 311
182 300 465
260 445 840
470 730 1150
694 1160 1800
1020
1660
2500
2
15
25
40
12
19
30
25
43
64
45
70
15
70 112 178
100 162 275
182 295 475
280 428 745
410 656 1010
715 1215 1895
1125 1755 2925
1580
2520
4175
3
15
25
40
16
26
41
37
56
87
60
100
157
93 152 250
127 225 375
245 425 595
385 632 1025
535 910 1460
925 1580 2540
1505 2480 4050
2040
3440
5940
4
15
25
40
19
30
49
42
63 116
70
115
197
108 180 295
156 270 456
281 450 796
432 742 1247
635 1080 1825
1166 1980 3120
1685 2925 4940
2460
4225
7050
5
15
25
40
22
36
59
49
81 131
87
135
225
128 211 338
187 308 495
352 548 855
526 885 1350
770 1265 1890
1295 2110 3510
2105 3540 5400
2835
5150
7870

Table :  Extract from table showing carrying capacities of steel pipes in kg/h of steam at the given velocities

The table above indicates the carrying capacities of steam pipes at differing velocities and thus is a reasonable guide to use for "on the spot" steam pipe sizing based upon the steam velocity. A velocity between 25 and 30 m/s is generally acceptable in short branch lines, and around 15 m/s for main steam distribution lines. Steam velocities much in excess of 40 m/s will produce an audible noise level and will cause erosion on pipe bends, valves, and other in line equipment.

An oversized steam pipe means an over expensive installation in capital cost, extra and unnecessary heat loss from the pipe and therefore the system is not energy efficient. Also more condensate is formed in the pipe because of the extra heat loss, and the wet steam decreases the performance of production plant.

An undersized steam pipe stands for a lower than satisfactory pressure at the user end because of the excessive pressure drop along the pipe. Also the possibility of steam starvation can affect the production and the increased velocity can lead to erosion problems and waterhammer damage.

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