are of 2000 HP., and drive aerators. The speed is 1800 ren Cutite jer me and the voltage 2590 One of these ma tule menstret from the bon m of the bed-plate, is 12 feet Ntall enters each tur one at the top and leaves at the bottom passing & surface condenser, of which one is provided de euch wint As the condensers are alongside the tur que foramos mi stairs are provided to lead to the getenton the sering in four-space over that required by horizonti mudines such as Fursons with the condensers arranged below them is no s un as one might at first expect. Teste made on the Camis ruline seem to show that it gains In efficiency by the use of superbeated steam and by a vacuum to much the same extent as a Parsons turbine. good CHAPTER XIII. SPEEDS AND SPACE. THE high rotary speed of steam turbines is a disadvantage in many cases. As is pointed out in Chapter XIV., this high speed was a great obstacle to the application of the steam turbine to the driving of ships, although the difficulties have now been overcome. The high speed has also prevented the steam turbine being used for many purposes for which reciprocating engines are employed. The high speed is, however, a distinct advantage in many cases. In the driving of rotary pumps and air propellers and compressors the high speed is usually advantageous. In the driving of electric generators, whether continuous current or alternating, high speeds mean (relatively speaking) small dimensions and small cost. When large-power Parsons turbines are used to drive continuous-current generators, the latter are made in duplicate to avoid commutator difficulties, the two dynamos being arranged tandem. This arrangement, although calling for more room, has its advantages. In considering which of two motors to adopt for any purpose, the amount of space required by these is usually a consideration of some importance, and at times of very great importance. Table XXX. allows the floor-space required by steam turbines to be compared with that required by some vertical reciprocating steam-engines. TABLE XXX. FLOOR-SPACE OCCUPIED BY STEAM TURBINES WITH ELECTRIC GENERATORS, AND VERTICAL RECIPROCATING ENGINES WITH ELECTRIC GENERATORS. 047* Ferranti Vertical Engine and 750-K.W. 23 feet x 15 feet Close Power Station, Newcastle-on-Tyne. One Parsons Turbine driving two Dynamos of a combined capacity of 1000 K.W. 232 square feet 0.23 Vertical Cross Compound Engine by D. Stewart Central Station of the Hartford Electric Light Three exlinder Compound Side-by-side Engine yehude Bakicam Nagina dy D. Stewart & The heights of two vertical reciprocating steam-engines are compared with those of two turbines in Table XXXI. TABLE XXXI. HEIGHTS OF STEAM TURBINES AND VERTICAL RECIPROCATING STEAM-ENGINES. The smallness of the head-room required by a steam turbine is, of course, of much less consequence when it is placed in an engine-room alongside of vertical reciprocating steamengines than when located in an engine-room built to receive turbines only. The floor-space and weights of steam turbines and gasengines are compared in Table XXXII. |