Redundant steam lines should either be removed or blanked. This saves the unnecessary distribution losses in the line.
When steam flows through a pipeline, there are some fixed losses that are associated with it called distribution losses.
These distribution losses may either be in the form of steam condensation that
occurs due to heat loss via radiation through steam lines or direct steam loss via
leakages.
It is sometimes observed that certain sections of a plant are operational only for
a portion of the year or have been discarded. However, steam continues to flow
into the lines in these sections. Thus, even though the sections are not in
operation, steam is consumed in order to make up for the fixed losses.
It is recommended that such redundant steam lines should either be removed or
blanked. This will reduce the unnecessary steam consumption and thus save
fuel.
Eg: In case of steam lines, the table below gives the amount of fuel (FO) lost
annually per meter length:
|
Pipe Size (mm)
|
Surface Temperature (°C/°F)
|
|
Uninsulated Steam lines
|
Insulated steam lines
|
|
50
|
100
|
150
|
50
|
|
25
|
15
|
74
|
160
|
7
|
|
50
|
28
|
133
|
288
|
13
|
|
75
|
40
|
190
|
410
|
19
|
|
100
|
50
|
250
|
472
|
25
|
|
150
|
68
|
360
|
680
|
38
|
Assumptions:
- Ambient temp : 30°C for still air
- Surface temperature of insulation: 40°C
- Total hrs of operation: 8100
- External pipe surface: Mild steel