11.4.3 Ocean Water Cooling. The use of ocean water as a source of cooling
adds the additional complication of an active corrosive fluid in the system.
The system must also be of the closed type with heat exchangers provided to
separate the primary and secondary cooling circuit fluids. Corrosion
resisting materials are required for seawater pumps, piping, and heat
exchangers, and special stainless steel alloys, titanium, or other exotic
materials are usually employed. Extensive experience has been developed
recently in the installation and operation of desalination plants of the
evaporator and Reverse Osmosis (RO) types. Remaining maintenance problems
center around the primary seawater pumps, filters, and piping elements.
Small reverse osmosis plants could be used to produce suitable makeup water
for radiator type cooling where no other source is available. Reverse
osmosis systems can also be used on brackish water or water with other
impurities to produce a satisfactory makeup water supply.
11.4.4 Exhaust Heat Reclamation. Where heat exchange silencers are
provided for cogeneration of hot water or steam, treatment of forced hot
water or boiler feed water shall conform with requirements of NAVFAC
DM-3.06, Central Heating Plants. See Table 11 for maximum boiler water
concentrations set by boiler manufacturers to limit their responsibilities
for steam purity. Boiler water concentrations should be kept below
(preferably well below) these limits by the following means:
intermittent or continuous blowdown,
raw makeup water treatment,
feedwater treatment, and
internal chemical treatment.
See Table 12 for the effectiveness of some typical water treatment
Maximum Boiler Water Concentrations
Multiply lb/in2 by 703 to obtain kilograms per square meter.
Follow boiler manufacturers recommended water quality criteria for
pressures above this level.