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DD-43 Casin - Boilers

There are four oil-burning Nonnand water-tube boilers, arranged in pairs in two separate compartments as shown in Fig. 3. They are designed to run the entire machinery plantat full power, with an average air pressure in the firerooms of about five inches of water. Each boiler has an independent smoke pipe 34 feet 6 inches high above the base line of the vessel. The fuel-oil pumps and heaters are located in the firerooms.

The plant consists of two light-service booster pumps, four heavy-pressure service pumps, two oil heaters, and the oil-storage tanks in the forward and after holds, together with the necessary piping and fittings. The booster pumps have suctions from all storage tanks and the deck connection for taking on oil, and discharge to all storage tanks, service pumps' suctions and the deck connections. The service pumps draw oil from the storage tanks and the booster pumps' discharges, and deliver it to the oil burners on the boilers, via the oil heaters or bypasses.

The burners, twelve per boiler, of the slightly modified Bureau of Steam Engineering type, are mechanical atomizers. Strainers areprovided in the pump suctions and discharges, and the supply pipes to the burners are fitted with cocks controlled from the deck as well as the firerooms. A small hand oil pump is installed in each fireroom for supplying oil to the burners when raising steam.

Four forced-draft blowers are installed, two in each fireroom. The fans are of the Keith single-inlet, horizontal type, mounted on vertical shafts in the base of the fireroom ventilators, from which the air supply is taken. Each fan is driven by a 24-inch Terry steam turbine located immediately below the fan.

There are two Warren, 15-inch X 10-inch X 16-inch auxiliary feed pumps, one in each fire- room. They are of the vertical, double-acting, single type and are arranged to feed any boiler, either through the feed- water heater or direct.

There are two main steam lines. The port line is connected to the two after boilers only, and that on the starboard side to the two forward boilers. The branches from the boilers are 7 inches in diameter each, and the lines proper are 9 inches, uniting in the engine room into a common 13-inch casting at the working platform. Beyond the throttle valve the pipe again divides into two gf-inch connections to the main H.P. turbine, and there is a 5-inch branch to the reciprocating cruising engine. A 2-inch bleeder pipe to the main condenser is provided.

There is a 3-inch stop valve on each boiler for supplying the auxiliary steam line, which leads throughout the machinery spaces with connections to the various auxiliaries and a branch forward to the deck machinery, forward heating system and galleys.

An auxiliary exhaust pipe extends throughout the machinery spaces and elsewhere as Required for the various auxiliaries. Connections are provided for direct exhaust into either the main or the auxiliary condenser, the feed-water heater, or into the atmosphere through the after escape pipe, at will. There are also connections for admitting exhaust steam into the L.P. turbine's steam belt and into the second and sixth expansions of the M.H.P. turbine when desired.

The main and auxiliary feed pumps take their suctions from the feed suction main, which extends from the bottom of the main feed tank to the auxiliary feed pump in the forward fire-room. The main is 8 inches in diameter in the engine room, decreasing in size to 7 inches in the after fireroom and 5 inches in the forward fireroom. The suction branches to all feed pumps are 5 inches in diameter. All feed pumps are arranged to feed any boiler via the feed heater or bypasses. The main feed line is 6 inches in diameter from the feed- water heater to first branch connection to boilers, decreasing in size to 5 to 4 inches, as it leads forward in the firerooms. The discharge from each pump is 4 inches and the branches to all boilers are 3 inches each. Each auxiliary feed pump also has a direct connection to all boilers, through a 4-inch independent main between the two firerooms.

The distilling apparatus is installed in the auxiliary machinery room. There are two evaporators and two distillers, with their accessories, arranged to operate in single effect. The plant has a combined evaporator capacity of 3,750 gallons of water per twenty-four hours, that of the distillers being only 2,500 gallons.



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