The Horizontal Steam Turbine For Stationary Plants 1920

succeeding set of moving blades (F7) of the turbine rotor. The upper half of the casing may be re- moved, for the examination of the rotor and blades and to facilitate repairs to the blading. The steam enters the turbine at the stop valve (H$) in the steam line (H3) and is dis- charged through oipe H4. The Rotor The turbine rotor consists of a shaft (F) on which is fixed a drum. On the circum- ference of the drum are blades (F7) which revolve between stationary blades (A2) fixed in the turbine casing (A). The shaft (F) is supported by bearings (Fz) and is held in correct position by thrust bear- ing (F8). This bearing takes up the axial, or end thrust, caused by the expansive pres- sure of the steam on the blades of the rotor in passing from the small to the large end of the turbine casing. The main bearings (F2) are cast with inside cavities (K) through which water circulates for cooling purposes. From the main shaft (F) is driven a vertical shaft (H6) on which is mounted the govemor (H7), which automatically maintains the speed of the turbine by the control of the requisite amount of steam. At each end of the tur- bine casing (A) are the giand TI packings (A3 and A4). Gland packing (A3) prevents steam leakage outward. Gland packing (A4) prevents air leakage inward wheri operating condensing or prevents steam leakage outward when operating non-con- densing. The exhaust steam from a non-condens- ing turbine is discharged to the atmosphere or is sometimes used for heating purposes. The exhaust steam from a condensing turbine is discharged into a condenser where it is cooled and condensed in a vacuum. Highest steam efficiency is thus obtained. The temperature at the exhaust end of a non-condensing turbine is raised by the temperature of the exhaust steam; whereas the vacuum utilized in a condensing turbine insures much lower operating temperatures at the exhaust end. Steam leakage out of, or air leakage into, the turbine would greatly decrease its effi- ciency, hence the adoption of gland packing. There are three types of gland packing as follows: Carbon packing Labyrinth packing Water seal Carbon Packing (Fig. 5) The carbon packing rings (1), made in several parts, are usually held in their places by means of helical springs (2) and fit into casing (3). The carbon rings (1) fit the shaft (F) closely, under slight pressure from 8