Principles of naval engineering - Historic Naval Ships Association

PRINCIPLES OF NAVAL ENGINEERINGPRESSURESWITCHSTOPS PUMPAT 800 PSIGFigure 9-22.— Fuel oil service system for forward plant, DLG 14 and DLG 15.147.80is installed to permit bypassing the fuel oilheaters in unusual operating situations. Fueloil heater valves control the flow of oil intothe heaters and permit shifting from one heaterto another.The main fuel oil valve controls the flowof fuel oil in the line leading to each boiler.The emergency quick- closing valve can beoperated from both the upper level and thelower level at the boiler front. In some installations,a latched-open solenoid valve, arrangedfor local tripping, is installed adjacent to eachburner supply manifold; where a solenoid valveof this type is installed, it takes the place ofthe emergency quick- closing valve.A micrometer valve is installed at the topof each burner manifold. The micrometer valveis used for the manual control of fuel oil pressure;thus it is the valve that controls the amountof oil being burned in the boiler furnace. Fromthe burner manifold, a small flexible line goesto each burner. A small valve called a burnerroot valve is installed in each burner line topermit shutting off the supply of oil to any burnerthat is not in use. And finally, an atomizervalve is installed on each burner at the atomizerconnection. This valve allows oil to go throughthe atomizer and be sprayed out into the boilerfurnace in such a way that combustion takesplace.At the lower end of each burner manifold,a recirculating valve is installed. By means ofthese valves and the recirculating line, fuel oilcan be returned from the burner manifold tothe suction side of the fuel oil service pump.The recirculating line is used to circulate oilthrough the fuel oil heaters and thus bring theoil up to the proper temperature for lighting224