Page 270 - Boiler plant and distribution system optimization manual

Chapter 14

Steam Traps

When steam expends its energy, by giving up
its heat or by doing work, it condenses back into
water (Figure 14.1). This water must be removed
from the pathway of the steam so it will not inter-
fere with the function of the steam system. Once
removed, the condensate, pure hot water, should
be returned to the boiler where it is again heated
to produce more steam.

Figure 14.2—Float trap is trapping steam while al-
lowing condensate to discharge.

a pipe is swept along by the high velocity steam
(Figure 14.3). As the water moves through the
pipe collecting additional droplets, forming a
larger arid larger slug, it develops a high level of
Figure 14.1—Condensate formation in steam distri-
energy and can cause serious damage through the
bution line. A valve is shown draining line instead
phenomena known as “Waterhammer.” Severe
of a steam trap.
waterhammer can burst the wall of a pipe, possi-
bly causing personal injuries and damaging other
The Purpose of Steam Traps
equipment in the area, it is usually accompanied
The job of removing condensate is handled
by a sharp metallic noise.
by the steam trap (Figure 14.2). The steam trap’s
job is to remove condensate while preventing
steam from escaping from the distribution sys-
tem. It must discharge this condensate from a
higher to a lower pressure. To do this job, it is
designed to differentiate steam from condensate,
usually by reacting to temperature, density or
thermodynamic properties.
The Btus which are released by steam in heat-
ing, and process applications and by pipe radia-
tion loss causes the steam to condense and form
droplets of water that can quickly combine into
larger masses. If this condensate is not effectively
removed (trapped), it can reduce the efficiency of
heat transfer equipment by a phenomena known Figure 14.3—Condensate accumulates in distribution
as waterlogging. piping and forms a slug which is carried along by the
Condensate accumulating at the bottom of steam at high velocity.
255