Figs. 2.2a, b, and c show the arrangement of the machinery in the engine room of a typical steam ship.
Usually, one enters the engine room at the main deck level and proceeds down the ladder to the fireroom on
the operating flat forward (Le., to the right, in these drawings) of the boilers. The capsule descriptions which
follow should be taken one-by-one, with equipment named located in any of the three drawings in which it
appears. Further information on the items named or visible in the drawings can be found through the index.
The fireroom is at the level of the furnaces of the boilers. This ship is typical in having two boilers,
and in burning fuel oil, designated as FO in these drawings.
The fuel oil is stored in bunker tanks built into the ship's hull in several locations. It is transferred
daily from these bunker tanks to the FO settling tanks in the engine room by the FO transfer
pump. In this example, the FO settling tanks and transfer pump are visible on the lower, or floorplate level, of the engine room. From the settling tanks, the fuel is delivered to the boiler furnaces by
the FO service pumps, via strainers and heaters.
The air needed for combustion of the fuel is supplied to the furnaces by the forced-draft fans, which
are located above the boilers.
Most of the steam produced in the boilers is passed to the propulsion turbines via the throttle
valves operated from the main console. The propulsion turbines require so many rows of the
windmill-like blades mentioned above, that they are divided into the two, separately encased units,
the high-pressure (HP) turbine and the low-pressure (LP) turbine, through which the steam
passes in series.
The turbine shafts spin too fast to drive an efficient propeller. The usual way to reduce the turbine
shaft speed is with a reduction gear, which also serves to combine the power produced by the HP
and LP turbines.