Transcript Document

PowerPoint® Presentation
Chapter 4
Steam and Water Accessories
Feedwater Heaters • Feedwater
Pumps • Surge Tank • Condensate
Tank and Pump Unit • Main
Feedwater Line • Steam Traps •
Desuperheating and PressureReducing Station
Chapter 4 — Steam and Water Accessories
The open feedwater
heater, located above the
feedwater pump on its
suction side, supplies
water to the pump at a
slight pressure.
Chapter 4 — Steam and Water Accessories
Because of its vent
condenser, the
deaerating feedwater
heater does a more
effective job of removing
oxygen and other
noncondensable gases
from the steam than an
open feedwater heater.
Chapter 4 — Steam and Water Accessories
The horizontal deaerating feedwater heater is used
when headroom is a problem.
Chapter 4 — Steam and Water Accessories
The closed feedwater heater is located on the discharge side of
the feedwater pump. Unlike the open feedwater heater, the
closed feedwater heater does not mix steam and water.
Chapter 4 — Steam and Water Accessories
In an economizer, gases
of combustion are used
to raise boiler feedwater
temperature. The gases
of combustion are then
released to the
atmosphere.
Chapter 4 — Steam and Water Accessories
A two-stage condensing
economizer recovers
additional heat from the
gases of combustion by
preheating the incoming
makeup water.
Chapter 4 — Steam and Water Accessories
In a duplex-reciprocating feedwater pump, the steam
piston must be 2 times to 2 1/2 times larger in area
than the water piston.
Chapter 4 — Steam and Water Accessories
In a centrifugal feedwater
pump, the centrifugal
force of the impeller
produces pressure.
Chapter 4 — Steam and Water Accessories
The two most common
centrifugal feedwater
pumps are the singlestage type and multiplestage type.
Chapter 4 — Steam and Water Accessories
Turbine feedwater pumps are positive-displacement
pumps and require an open discharge valve when
starting.
Chapter 4 — Steam and Water Accessories
A surge tank provides the
extra capacity required to
handle changing loads
and peak flows of
condensate in larger
steam boiler plants.
Chapter 4 — Steam and Water Accessories
Condensate pumps are
used to return all
possible condensate
from various parts of the
plant to the open
feedwater heater.
Chapter 4 — Steam and Water Accessories
The main feedwater line utilizes check and stop
valves to control water flow.
Chapter 4 — Steam and Water Accessories
When a feedwater pump
feeds more than one
boiler, each boiler should
be isolated with a globe
valve.
Chapter 4 — Steam and Water Accessories
The thermoexpansion
feedwater regulator
thermostat is located at
the NOWL and is
connected to the steam
and water side of the
boiler.
Chapter 4 — Steam and Water Accessories
A two-element feedwater
regulator has a
diaphragm assembly on
the top part of the
regulator valve that
senses the pressure
differential from the
superheater.
Chapter 4 — Steam and Water Accessories
A three-element feedwater regulator is used for
closer control of water level in large watertube boilers
with sudden fluctuations in steam load, and/or boilers
equipped with economizers.
Chapter 4 — Steam and Water Accessories
A thermohydraulic feedwater regulator operates when
boiler water level increases or decreases.
Chapter 4 — Steam and Water Accessories
Float feedwater regulators may be installed inside or
outside the water column, depending on their design.
Chapter 4 — Steam and Water Accessories
Steam traps are located
in the system wherever
steam releases its heat
and condenses. Steam
strainers are installed
before steam traps.
Chapter 4 — Steam and Water Accessories
The thermostatic steam
trap can be used with
both high and low
pressure steam.
Chapter 4 — Steam and Water Accessories
The float thermostatic trap
removes air and other
noncombustible gases as
well as condensate.
Chapter 4 — Steam and Water Accessories
Inverted bucket steam
traps are used when
large quantities of
condensate must be
removed.
Chapter 4 — Steam and Water Accessories
An impulse steam trap
valve opens when
condensate or air
entering the trap causes
a pressure drop above
the control disc.
Chapter 4 — Steam and Water Accessories
In a thermodynamic steam trap, pressure of the air or
condensate enters the inlet port under the center of
the disc and lifts the disc from its seat to discharge
condensate.
Chapter 4 — Steam and Water Accessories
In a variable orifice (labyrinth) steam trap, the steam
and condensate enter the body and pass through a
series of compartments that reduce the pressure.
Chapter 4 — Steam and Water Accessories
Drum desuperheaters are used primarily on marine
boilers.
Chapter 4 — Steam and Water Accessories
The quantity of steam
increases with the use of
a line desuperheater.
Chapter 4 — Steam and Water Accessories
Plants often require steam at different pressures.
Steam at the required pressure is supplied by using
pressure-reducing stations