Page 177 - Boiler plant and distribution system optimization manual
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162 Boiler Plant and Distribution System Optimization Manual
All steam used by the system must pass heating make up water to system operating tem-
through steam traps, so the whole system is sub- perature. One point often overlooked is that boil-
ject to this loss if atmospheric vents are used. er inefficiencies are doubled in this case, because
Closed pressurized condensate recovery systems the steam in these leaks must be generated twice
are used in well-designed plants to avoid this to use it once.
problem. If the pure hot water is not brought back
to the plant by the condensate recovery system, Internal Steam Leaks
then the expense of new water, its chemical treat- Internal steam leaks are hard to detect, they
ment and heating it back to operating tempera- are inside the piping system, and common sense
ture will just add to avoidable plant expenses. indicates there are such leaks. Steam traps are in-
stalled with bypass valves which are often opened
Advantages/Disadvantages in the event there is a problem with the trap like
If you are not getting the condensate back plugging. The bypass valves are often opened on
from your steam system you are incurring about start up or when water hammer becomes a prob-
a 17% loss from that fact alone. lem in the system to drain water from the system.
Steam driven equipment such as turbines and
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Rule of Thumb pumps have drains and warmup systems and
Every 11 deg F [6 deg C] that these can be left open too. The fact is steam can be
must be added to boiler slipping through the system without doing any
feedwater costs 1% in efficiency. work
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8. OPTIMIzE DEAEREATOR VENT RATE
6. REPAIR CONDENSATE RECEIVERS, (Figure 10.58)
PUMPS AND PIPING
Water seems to be such a common and cheap 9. INSULATE THE FEEDWATER SYSTEM
commodity and it is not assigned its real value to
steam system management. The water in the feedwater system is at the
boiling point which could be 212F or higher de-
When conditions are not observable or
pending on the pressure in the system. The deare-
known, the assumption is often made
ator and reserve feedwater tank are typical of
that they are negligible .
such systems. The large surface represents a large
loss of heat if not insulated. (Figure 10.59)
In steam systems, most of the losses are
not observable. Unfortunately they are
quite large and far from negligible .
10. USE HIGH-PRESSURE CONDENSATE TO
MAKE LOW-PRESSURE STEAM
7. REPAIR STEAM LEAKS The high pressure condensate recovery sys-
tem can be a source for low pressure steam use in
External Steam Leaks the plant or for other uses.
External steam leaks are usually visible and
the length of the plume can be measured by eye.
For example, if there are 4 visible steam 11. PRESSURE REDUCING VALVES
leaks, two 6-foot plumes and two 8-foot plumes,
this would work out to nearly $100,000 a year loss Potential Savings
plus the cost of water, chemicals and fuel wasted Moderate
