tank collects the water from the condensate cooler
and maintains a supply of water for the boiler.
are discharged through the exhaust gas outlet.
Makeup feedwater is supplied to the tank from
the distilling plant. Additionally, provision is
Condensate Collecting System
made through an air gap (funnel) to the freshwater
system for an emergency supply.
The condensate collecting system collects the
Tank level is automatically controlled by a
condensate from the control condensers, distilling
float-type level controller. When the water level
plants, and hot-water heating system and returns
in the tank drops below a set level, the makeup
it through the condensate main to the condensate
feedwater solenoid valve opens and makeup feed-
cooler. This condensate is monitored for salinity.
water flows into the tank. When the tank is full,
Figure 7-34 is a system schematic showing the flow
the makeup feedwater valve closes, thus shutting
of condensate, feedwater, and steam through the
off the flow of makeup feedwater.
The level controller also contains switches for
high- and low-water level indicating lights located
CONTAMINATED DRAIN INSPEC-
on the boiler control panel and at the PACC.
TION.--Condensate from the fuel or lube oil
heaters is returned by the oily condensate main.
From the oily condensate main, the condensate
FEEDWATER PUMP.--The purpose of the
passes through the contaminated drain inspection
feedwater pump is to supply feedwater to the
tank where it is monitored for the presence of oil
boiler to maintain the proper water level in the
reservoir during boiler operation.
main. The inspection tank is equipped with a UV
oil detector that continuously and automatically
DEAERATING FEED TANK.--An addition
monitors the condensate for oil contamination.
to the waste-heat boiler that is being installed on
When oil is detected, the associated solenoid-
all ships at the present time is the deaerating feed
operated valve diverts the contaminated conden-
tank (DFT) system. The purpose of this system
sate to the waste-oil drain system. Alarm
is the removal of gases in the feedwater which,
indicators are located at the control box and the
in the case of oxygen, leads to corrosion and
pitting of the internal surfaces of waste-heat boiler
The alarm and warning circuits remain
tubes and other equipment.
The feedwater booster pump takes feedwater
the set point. However, when contamination
from the feed and drain collecting tank and directs
drops below the set point, the alarm and warn-
it to the subcooler. This feedwater is used to cool
ing indicator lights extinguish and the associated
the water from the DFT before it enters the feed
solenoid-operated valve closes. The contaminated
pump. Feedwater leaves the subcooler and flows
drain tank is equipped with a sight glass for visual
through the DFT feed control valve. The DFT
feed control valve is an air-operated valve; it
controls the flow of feedwater to the DFT. It is
CONDENSATE COOLER.--The condensate
used to maintain normal water level in the DFT.
cooler is of the shell and tube design with the
A spillover valve is also used to prevent a high-
coolant (seawater) flowing through the tubes. An
water level from occurring and to maintain a
air-operated valve in the seawater outlet piping
minimum feedwater flow. Feedwater flow from
and an air temperature controller regulates the
the spillover valve is returned to the feed and drain
flow of seawater to control the output temper-
collecting tank through the condensate cooler.
ature of the condensate cooler.
The deaerated water drops into the storage
space at the bottom of the DFT, where it remains
SALINITY INDICATING SYSTEM.--The
until it is pumped to the waste-heat boiler by the
salinity indicating system monitors the condensate
feedwater pump. Meanwhile, the mixture of steam
return system. The system has a bell and dump
plus air and other noncondensable gases travels
module, salinity indicator and controllers, and
up. The steam-gas mixture then exits the tank and
salinity cells for monitoring the control condenser
flows to the external vent condenser. The remain-
and condensate cooler drains.
ing steam is condensed in the vent condenser and
the water is returned to the feedwater holding
FEEDWATER AND DRAIN COLLECT-
tank, The air and other noncondensable gases are
ING TANK.--The feedwater and drain collecting