Twentieth century hand-book for steam engineers and electricians, with questions and answers .. . olled by piston valves, which are actuated bysteam from small pilot valves which are in turn underthe control of the governor. Fig. 139 shows the formof governor for a 5,000 K. W. turbine, and Fig. 140shows the electrically operated admission valves forone set of nozzles. Speed regulation is effected by varying the numberof nozzles in flow, that is, for light loads fewer nozzlesare open and a smaller volume of steam is admitted tothe turbine wheel, but the steam that is admittedimpinges the moving
Twentieth century hand-book for steam engineers and electricians, with questions and answers .. . olled by piston valves, which are actuated bysteam from small pilot valves which are in turn underthe control of the governor. Fig. 139 shows the formof governor for a 5,000 K. W. turbine, and Fig. 140shows the electrically operated admission valves forone set of nozzles. Speed regulation is effected by varying the numberof nozzles in flow, that is, for light loads fewer nozzlesare open and a smaller volume of steam is admitted tothe turbine wheel, but the steam that is admittedimpinges the moving blades with the same velocityalways, no matter whether the volume be large orsmall. With a full load and all the nozzle sections inflow, the steam passes to the wheel in a broad belt andsteady flow. The Curtis Steam Turbine is the result of the investi-gations and experiments of Mr. C. G. Curtis of New THE CURTIS STEAM TURBINE 370 York, and while retaining the advantage of the expand-ing nozzle of De La\ral, it at the same time utilizes theenergy acquired by velocity, by causing the steam to. FIGURE 139. GOVERNOR FOR 5,000 TURBINE. impinge the moving buckets of two or more wheels insuccession. A portion of this velocity force is givenup in the first stage, and another portion in the secondstage, and this process is repeated, the steam in each 380 ENGINEERING case being first caused to expand in divergent nozzlesand thus acquire new velocity before it is allowed toimpinge the moving blades of the next lower stage. Thepressure in each succeeding stage of expansion becomeslower and lower, until finally vacuum is reached. As previously stated, two of the main sources ofeconomy that the steam turbine possesses in a muchhigher degree than does the reciprocating engine are: first, its adaptabilityfor using super-heated steam, andsecond, the possibil-ity of maintaining ahigher degree ofvacuum. k The efficiency I I shown by the steam HH 1 turbine is certainly ^mx^- - ? ; remarkabl
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