Page 147 - Steam Turbines Design, Applications, and Rerating

128 Chapter Seven

Figure 7.4 Trip valve arrangement used on some small
steam turbines. (Dresser-Rand Company, Wellsville, NY)

oil pump (4) makes sure that an oil film exists between bearing and
journal (shaft) surfaces from the very instant rotation commences.
The oil cooler (5) and filter (6) are duplicated so that they can be
maintained while the set is running. The oil filter has a mesh width of
10 to 15 μm.
Many turbines obtain their lubrication requirements from a com-
bined lube system that also serves the driven machinery and that
would customarily be furnished by the driven equipment vendor. Our
companion text, A Practical Guide to Compressor Technology, deals
with these supply systems in considerably greater detail.

7.2 Barring or Turning Gears
Barring or turning gear units are depicted in Fig. 7.2. Large steam tur-
bines are customarily equipped with these devices. Turning gear units