stacks, to determine the true state of combustion
efficiency.
NOTE: In boilers using distillate fuel, excess air
can cause abnormally high superheater outlet
temperatures, especially on “D” type boilers. Be very
careful to prevent leakage of air into a boiler. Air that
enters a boiler at any place other than through a burner
register does not contribute to furnace combusiton and
may reduce combustion efficiency.
. Watch carefully for chloride contamination of the
water in the boiler feed and condensate systems; it
threatens the material integrity and operational
readiness of the plant. Keep in good working order those
means used to determine the chloride content of boiler
water. Drill operating personnel frequently on the
danger of, and the methods used to prevent, chloride
contamination. Be sure the DFT is functioning properly
to remove dissolved gases from the boiler feedwater.
l Conduct daily dissolved oxygen tests on water to
steaming boilers and on the discharge side DFT if your
ship has them. You don’t want dissolved oxygen in any
boiler, but it is particularly corrosive in boilers that
operate at high pressures and high temperatures. The
modern pressure-closed feed system is designed to keep
the condensate and feedwater from being exposed to air,
and the DFT is designed to remove a great deal of
oxygen that becomes dissolved or entrained in the water.
However, there are still many ways in which oxygen can
get into the system and become dissolved in the water.
For example, a defective DFT may allow the water to
pass through without being deaerated. Incorrect
operation of a DFT can have the same effect. Air can
leak into the condensate and feed systems at various
points and its oxygen can dissolve in the water. Failure
to lay up idle boilers according to prescribed procedures
is still another cause of dissolved oxygen. You can find
more information on dissolved oxygen tests in NSTM,
chapter 220.
. The Oil King and the engineering watch
supervisors in the fireroom should be graduates of the
Boiler Feedwater Test and Treatment Course. They
should be certified to perform the feedwater tests and
treatments that are prescribed by Naval Sea Systems
Command (NAVSEASYSCOM) and the manufacturer
of the boilers. Never assume that personnel who conduct
these tests are competent, observe them personally and
be sure.
. Always preheat the lubricating oil system before
starting the engines. During operating periods, keep the
oil from the oil cooler between 120 and 130 degrees to
minimize bearing wear. Watch for overheated bearings,
foaming or emulsified oil, the presence of bearing metal
and other foreign particles in lubricating oil sumps, and
the presence of rust on journals and gearing.
. When condensers and their auxiliary
components are operated improperly, they can cause
extensive loss of efficiency. Here are several examples.
—
—
l
When you use more than the required amount of
cooling water, the condensate system pumps a
large amount of heat overboard, and the boilers
will have to replenish that lost heat. You’ll get the
same effect from recirculation of the condensate.
Air leaks in the condenser or its components may
overload the air ejectors and lower the vacuum.
Steam is wasted by fluctuating, or excess, steam
pressure to the air ejectors and by steam-driven
auxiliary pumps operated at higher-than-
necessary speeds.
When the weather is cold enough to require
steam heat, try to operate ventilation motors in fresh air
supply systems at slow speeds. If you must operate them
at higher speeds, first secure the steam to preheater and
reheaters, but never operate supply blower motors faster
than necessary for comfort. It is usually more efficient
to circulate fresh air in a compartment by operating the
exhaust blower at a faster speed.
. Keep engineering spaces, equipment, and
machinery clean–it is one of the most important sound
engineering practices. Clean up trash and spilled oil to
prevent accidents and fire. Keep machinery free of oil
and dirt so oil and fuel leaks are easily visible. Repair
all leaks promptly. NEVER hose down spaces above the
level of the bilge deck plates–you may get water in
electrical assemblies. Clean spaces, equipment, and
machinery show pride in your work and your ship.
You can find information on performance data and
operating limits of the plant’s equipment and machinery
in the NSTM, manufacturers’ technical manuals, and the
Ship Information Book (SIB). For older ships, look in
the General Information Book, the Piping System
Instruction Book, the Record of Electrical Installations,
the Electrically Operated Auxiliaries With
Performance Data, and General Description of
Electronics System Installation.
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