The Horizontal Steam Turbine For Stationary Plants

THE HORIZONTAL STEAM TURBINE STATIONARY PLANTS Field of Service; Classification; Types; Construction; Princip le of Operation; Transmission of Power; Lubrication; Oil; Deposits FIELD OF SERVICE Horizontal steam turbines for stationary plants are built in a wide range of sizes. Small turbines, up to 300 hp., running 30,000 to 3,000 revolutions per minute are used for operating high speed centrifugal pumps, for driving exhausters, exciter sets, small lighting plants, etc. Turbines from 300 to 50,000 hp., run- ning from 3,600 to 750 revolutions per minute, are used to drive electric generators furnishing power and light in collieries, Steel works, paper miils, textile milis, Street rail- way and industrial power stations. CLASSIFICATION Steam turbines are classified according to the way in which steam is used: High Pressure Turbines Exhaust Turbines Mixed Pressure Turbines High Pressure Turbines High pressure turbines use steam at a boiler pressure of from 160 Ibs. to 200 Ibs. per square inch. The steam, before it leaves the boiler, is sometimes further heated, as a result of which its maximum value in heat units is utilized. The resultant dry steam is called superheated steam. Exhaust Turbines Exhaust turbines use the exhaust steam from reciprocating engines, i.e., plant en- gines, steam hammers, rolling mili engines, colliery winding engines, etc. The pressure of exhaust steam is low, only a few pounds per square inch. Before entering the turbine, the steam passes through an accumulator or receiver (a large enclosed reservoir) which establishes a regular flow of steam from the reciprocating engines to the turbine. Where exhaust steam from large recip- rocating engines is used, it is necessary that impurities in the steam, carried over from the boilers, and the excess oil used in steam cylinder lubrication, be thoroughly separated from the steam. Otherwise the turbine blades will become coated and the power of the turbine diminished. Exhaust steam is always very moist, and carries fine particles of water in suspension. The steam usually is cleaned by means of separators placed in the exhaust steam lines between the engine and the turbine. 5