Page 144 - Steam Turbines Design, Applications, and Rerating

Chapter
7

Turbine Auxiliaries

Among steam turbine auxiliary systems we find lubricating oil supply
consoles, barring or turning gear units, trip-throttle or similar emer-
gency stop valves, gland sealing arrangements, and lube oil reclaimers
or purifiers.

7.1 Lube Systems
Lube systems for steam turbines are not significantly different from
oil supplies for centrifugal compressors or other turbomachines. Al-
though lube oil supply systems come in numerous layouts and config-
urations, they would essentially embody the principal components
shown in Fig. 7.1.
The oil supply system is designed to cope with the requirements of
the turboset or equipment train. Figure 7.1 shows the lubricating sys-
tem for a turbine used to drive a generator direct, i.e., without gearing.
When a process machine is driven through gearing, the main oil
pump (1) is often driven by a gear shaft. In high-reliability units, three
independent oil pumps ensure that the bearings receive sufficient
lubricating oil at all operating conditions.

■ The main oil pump (1) driven either off the turbine shaft or through a
gearing shaft supplies oil for lubrication while the turboset is running.
■ The auxiliary oil pump (2) designed for 100 percent capacity supplies
lubricating oil while the set is being started up or running down. It
is usually a gear oil pump (like the main pump) and is driven by an
AC motor.
■ The battery-operated emergency oil pump (3) is generally a centrifu-
gal pump and designed to supply 40 percent of the required amount

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