DD-47 Aylwin - Boilers
Four oil-burning White-Forster water-tube boilers, designed to run the machinery plant at full power with an average air pressure of not more than six inches of water, are arranged in pairs in two separate compartments. Each boiler has independent smoke pipe provided with an air space. The smoke pipes are of oval cross-section of 16.57 square feet area, and are 30.05 feet in height above the oil burners.
The fuel-oil pumps and heaters are located in the forward and after firerooms. The plant consists of two light-service booster pumps, four heavy-service supply pumps, two oil heaters, and the oil-storage tanks in the forward and after holds, with the necessary pipes and fittings.
The booster pumps have suctions from all storage tanks and the deck connections for taking on oil, and discharge to all storage tanks, supply-pump suctions and to deck connections. There are also connections to these pumps to draw the water which has settled in the oil tanks and discharge it overboard. Strainers are fitted in the pump suctions and discharges, and the supply pipes to burners are provided with cocks controlled from both the fireroom and deck.
For raising steam when no air presstire is available, there is provided in each fireroom a small hand pump designed to deliver oil to two burners at about 200 pounds pressure.
There are two blowers for each fireroom. These 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. The blowers in the after firerooms are provided with ducts drawing air from the engine room. These ducts are provided with dampers operated from the fireroom floor. Each fan is driven by a 24-inch Terry turbine located immediately below the fan.
In each fireroom there is a feed-water heater of the dead-end type, installed on the discharge side of both the main and auxiliary feed pumps. The heating agent is the exhaust steam, a back pressure being kept in the auxiliary exhaust line for this purpose. In each fireroom there is a Blake, 15-inch X 10-inch X 16-inch auxiliary feed pump. They are of the vertical, simplex, piston type, and so arranged as to feed any of the boilers, either through the feed heaters or direct.
There are two main steam lines. The port line is connected to the two after boilers only, and the starboard line to the two forward boilers. The main steam line is 9-l/2 inches in diameter, with 7-inch branch pipes to the boilers. There is a 4-inch stop valve on each boiler for supplying the auxiliary steam line, which leads throughout the -machinery space with connections to the various auxiliaries, and a branch leading forward to the deck machinery, forward heating system and galleys.
An auxiliary exhaust line is led throughout the machinery space and elsewhere, as required, for the various auxiliaries. Connections are provided for direct exhaust into either main or auxiliary condensers, either feed-water heater, or into the atmosphere through the after escape pipe. There are also connections for admitting exhaust steam into the llth stage of each turbine, when so desired. From the feed tank, a pipe is led to the stop valves on the main feed pumps in the engine room and on auxiliary feed pumps in the fireroom.
The main feed pumps will discharge through a 5-inch main leading to the boiler compartments. This pipe branches in theafter fireroom into a 4-inch pipe for the boilers in that compartment, and into another 4-inch pipe leading to the forward fireroom for the boilers there. From these branches 3-inch pipes are led to the individual boilers. All feed pumps are arranged to feed any boiler via the main feed line, and through the feed heater or by-passes. In addition, each auxiliary feed pump has direct connection to the boilers in its own fireroom.
The evaporators are located in the auxiliary room, with the distillers located in the after engine-room hatch at a high elevation. There are two evaporators and two distillers, with their accessories, arranged to operate in single effect. The plant has a combined capacity of 3,000 gallons of water per twenty-four hours.
For performing minor repairs one small Hendey-Norton motor-driven engine lathe, of 12 inches swing and 6-foot bed, is installed, together with all the necessary tools and attachments. The dynamos are located in the forward starboard corner of the engine room. The installation consists of two horizontal, compound-wound, direct-current, 5-kilowatt, General Electric generators, each driven by a Curtis steam turbine. Each generator will deliver 40 amperes at 125 volts, when making 5,000 revolutions per minute.
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