Principles of naval engineering - Historic Naval Ships Association

CHAPTER 9MACHINERY ARRANGEMENT AND PLANT LAYOUTTo understand a shipboard propulsion plant,it is necessary to visualize the general configurationof the plant as a whole and tounderstand the physical relationships among thevarious units. This chapter provides generalinformation on the distribution and arrangementof propulsion machinery in conventional steamturbine propulsion plants and on the arrangementof the major engineering piping systemsthat connect and serve the various units ofmachinery.It is important to note that the informationgiven in this chapter is general rather thanspecific. No two ships— not even sister shipsareexactly alike in their arrangement of machineryand piping. The examples given in thischapter are based on the arrangements usedin various kinds of ships, large and small, oldand new. The examples give some idea of thevariety of arrangements that may be found onsteam-driven surface ships, and they indicatethe basic functions of the machinery and piping;but the examples cannot provide an exactpicture of the machinery and piping on any oneship. For detailed information concerning thearrangements on any particular ship, it isnecessary to consult the ship's blueprints,various ship's manuals, and the manufacturers'technical manuals that cover the engineeringequipment and piping systems installed in theship.ARRANGEMENT OF PROPULSIONMACHINERYThe propulsion machinery on conventionalsteam-driven surface ships includes (1) thepropulsion boilers, (2) the propulsion turbines,(3) the condensers, (4) the reduction gears, and(5) the pumps, forced draft blowers, deaeratingfeed tanks, and other auxiliary machinery unitswhich directly serve the major propulsion units.On most steam-driven surface ships otherthan oilers, tankers, and certain auxiliaries,the propulsion machinery is located amidships.Turbogenerators and their auxiliary condensersare usually located in the propulsion machineryspaces; other engineering equipment that is notdirectly associated with the operation of themajor propulsion units may be located in ornear the propulsion machinery spaces or inother parts of the ship, as space permits.A word about terminology may be helpfulat this point. The boilers in a propulsion plantmay be identified as propulsion boilers (oroccasionally as main boilers) when it is necessaryto distinguish between propulsion boilersand the auxiliary boilers that are installed onsome ships. The turbines are identified aspropulsion turbines when it is necessary todistinguish between them and the many auxiliaryturbines that are used on all steam-driven shipsto drive pumps, forced draft blowers, and otherauxiliary units. The propulsion turbines arealso sometimes referred to as the main engines,although this usage is not considered particularlydesirable. The term propulsion unitis correctly used to identify the combinationof propulsion turbines, main reduction gears,and main condenser in any one propulsion plant;however, the term propulsion unit may alsobe used in a more general sense to indicateany major unit in the propulsion plant.Each propulsion shaft has an identifyingnumber which is based on the location of theshaft, working from starboard to port. Theshaft nearest the starboard side is the No. 1shaft, the one next inboard is the No. 2 shaft,and so forth. On recent ships, the propulsionmachinery that serves each shaft is given thesame number as that shaft. For example, theNo. 2 shaft is served by the No. 2 propulsionunit and the No. 2 boiler. Where two similarunits serve one shaft, the identifying number193