The Horizontal Steam Turbine For Stationary Plants

LUBRICATION There are two principal methods of turbine lubrication. Oil Circulation System—for the large sized turbines of 300 horse power and over. Ring-oiled bearings. These are usually employed on the smaller turbines up to 300 horse power in size; sometimes ring-oiled bearings are employed on the largest sized tur- bines. O il Circulation System (Fig. 4) From the lower portion of the go vemor spindle (H6, Fig. 4) is driven the rotary oil pump (T4), which takes oil from the oil tank (T3) and delivers it, through the oil cooler (T6), directly to the bearings (F2) through oil supply pipes (Ti), or to the elevated tank (T). Generally the oil passes from the oil cooler directly into the distributing pipe (Ti); it then becomes necessary to have a spring- loaded relief valve (Ti2) in the delivery pipe, near the bottom oil tank, in order to main- tain an adequate oil supply at a steady pres- sure. The surplus is retumed to the bottom oil tank (T3). From the bearings the oil returns through return pipes (T2) to the bottom oil tank (T3) through the strainer (T8). Oil throwers (Fi 1) prevent the oil from creeping out along the shaft from the bearings. If more oil is delivered to the elevated tank (T) than is required for the bearings, the sur- plus oil overflows through the pipe (T7) into the bottom oil tank (T3). The elevated tank (T) is nearly always omitted except in very large installations. From an elevated tank (T) the oil is fed through the distributing pipe (Ti) into the various bearings of the turbine. It is good practice to have inserted in the return oil pipes (T2), sight feed arrange- ments by which the actual flow of oil from each particular bearing can be examined. Frequently test cocks (Tg) are fitted in the middle of the bearing tops, which, when opened, will show whether the bearing is being adequately supplied with oil. In both the elevated oil tank (T) and the bottom oil tank (T3) are fitted drain cocks (Tio), through which water and sludge can be drained away. Frequently the oil is also used for operat- ing the governor gear (not shown). For this purpose oil is introduced into the various parts of the governor gear operated by the oil at a pressure of from 25 Ibs. to 80 Ibs. per square inch. Occasionally one oil pump is used for supplying oil for bearing lubrication and another pump for supplying small quantities of oil under high pressure, for the governor Fig. 9. Turbine connected to generator through a reduction gear (turbine and gear cover removed) 11