MINIMIZING HEAT LOSSES
THROUGH STEAM TRAP
ENERGY MANAGEMENT
steam trap is a device
attached to the lower
portion of a steam filled
line or vessel which pass
condensate but will not
allow the escape of steam, or A steam trap
is a piece of equipment that automatically
controls the condensate removal, air and
carbon dioxide from a piping system with
minimal steam loss.
A
The hot condensate removal is very
necessary to prevent water hammer,
which is capable of damaging or
misaligning piping instruments.
It is also very desirable to avoid air in
the steam system as any volume of air
consumes part of the volume that the
system would otherwise occupy. Apart
from that, the temperature of air/steam
mixture normally falls below that of pure
steam.
Again, it has been prove that air is
an insulator and clings to pipe and
equipment surfaces resulting to slow and
uneven heat transfer.
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PECM Issue 32
Traps are used on steam mains, headers,
separators, and purifiers, where they
remove water formed as a result of
unavoidable condensation or carry-over
from the boilers. They are also used on
all kinds of steam heating equipment
in which the steam gives up heat and
is converted to condensate. Coils are
used in heating buildings in water
heaters, and in a wide range of industrial
processing equipment are included in the
classification.
Whether a trap is used to keep
condensate from accumulating in a
steam line or to discharge water from a
steam heated machine, its operation is
important. If it leaks, steam will be wasted;
if it fails to operate, water will accumulate.
A satisfactory trap installation must pass
all the water that flows to it without
discharging steam, and must not be
rendered inoperative by particles of dirt
or by accumulation of air, and must be
rugged in construction with few moving
parts, so that it will remain operative with
a minimum of attention.
The presence of carbon dioxide reduces
heat transfer because the steam pushes
it to the walls of heat transfer surfaces.
Secondly, carbon dioxide also dissolves
in the condensate to form carbonic
acid, which may corrode piping and
equipment.
A strainer is usually installed in the line
ahead of the trap, to prevent sediments
from stopping up the trap orifice. When
selected in the correct pressure and
provided with strainers these traps will
give satisfactory service.
Traps are termed “non-return” when the
condensate is discharged into a receiver
or heater rather than directly to the boiler.
A “return” trap delivers the condensate
directly to the boiler. Return traps are
located above the boiler, and when filled
with water a valve automatically opens
and admits steam at boiler pressure. This
equalises the pressure and the water flows
into the boiler as a result of hydrostatic
head caused by the elevation of the
trap. These traps are sometimes used in
connection with low pressure heating
boilers.