Page 281 - Boiler plant and distribution system optimization manual
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266 Boiler Plant and Distribution System Optimization Manual
$2000 in steam each day—even though $500 bottom of the reservoir is a dirt pocket and valve
or more is spent daily on steam trap mainte- to collect larger particles of scale and dirt in the
nance.” system. It has a blowoff valve for clean-out.
Industry Week The condensate flows from the collection
April 16, 1984 point through a strainer and trap to the conden-
sate system. The station is configured with inlet
and outlet valves to isolate the trap if repairs are
needed.
This review of some of the most prestigious The test connection can be opened, coordi-
and informed publications on efficient plant man- nated with the closing of the trap outlet valve to
agement are all of one voice. There is tremendous see what is coming through the trap, steam or
potential to waste energy in steam systems, also condensate. This is one of the best ways to test
there is the same level of opportunity to correct trap performance.
the situation. The “Y” strainer can be cleaned out by open-
ing the blowoff valve.
The bypass line (not shown) enables plant
STEAM TRAP SELECTION SIzING personnel to bypass the entire steam trap station
AND INSTALLATION if necessary. Bypass valves are usually opened
when there is a suspected problem with a trap or
Steam Trap Piping to assist with drainage during cold startup. By-
In most plants, the removal of condensate passing a steam trap may also be necessary to
and air from steam systems is accomplished deal with a waterlogging problem caused by a
through steam trap stations. Figure 14.21 shows trap malfunction.
the piping configuration for a steam trap station. With the bypass open, steam will be wasted
and the efficiency of the plant reduced. In some
cases a trap is installed in the bypass line. Then,
if the main trap fails, the bypass trap can be put
into service and the problem of blowing steam
through the bypass is eliminated.
Selecting the Type of Trap
Properly selected, sized and installed traps
are the best guarantee for efficient operation, long
service life and minimum downtime.
The major considerations in selecting the
type of steam trap are:
A. Type of service
• Continuous or intermittent removal of
Figure 14.21—A typical steam trap station. condensate
• Temperature of the condensate and sys-
The first part of the steam trap station is a tem pressure
reservoir that connects to the lowest point of the • Range of load on the trap
steam line or process equipment. The reservoir • Rate of change of the load
is sized to collect the large quantity of conden-
sate formed during the warmup phase when the B. Operational
system is brought up from the cold state. At the • Normal steam loss during operation
