THE STEAM TURBINE
CHAPTER I.
INTRODUCTION.
THE steam turbine is the most modern as well as the most ancient steam motor. Recently its development has gone by leaps and bounds; and, above all, in its applications it is gaining ground daily. Doubtless it is to be the most important prime mover of the near future.
During recent years results have been secured with steam tur- bines that only a short time ago were considered practically unat- tainable. Primarily their great success lies in their adaptability to operation with high vacuums. Steam turbines are, therefore, almost ideally suitable for the conditions of modern engineering practice requiring both high vacuums* and high superheats. To-day in the economical use of steam they are unrivaled; and, because of improved manufacturing methods, marking the tran- sition from the experimental to the commercial stage, first cost is no longer a deciding factor favoring reciprocating engines. Compared with reciprocating steam and gas engines, steam turbines require much smaller and cheaper foundations, occupy less floor space, require fewer attendants, and because no lubrica- tion is required for any parts in contact with the steam, the con- densation becomes directly available for feed water. The highest superheats can be employed without affecting the choice of lubri- cants, and the cost of oil for lubrication is very low. A steam turbine of the simplest type is essentially a wheel similar to an ordinary water wheel, which is moved around by a steam jet impinging on its blades. Steam is directed against the turbine wheel by nozzles or similar passages delivering the
- The question of the most profitable vacuum for given conditions is discussed
on pages 273 to 281.
I
