Gas Turbine Handbook : Principles and Practices

Accessories 85
Chapter 6
Accessories
Accessories include the starting system, ignition system, lubrication
system, air inlet cooling system, water or steam injection
system (for NO x
control or power augmentation), and the ammonia
injection system (for NO x
control). The starting, ignition, and
lubrication systems are covered in this chapter. The air inlet cooling
system is discussed in Chapter 8, and the water or steam injection
systems and the ammonia injection system are treated in Chapter 9.
Accessory systems are considered direct drive when they are
connected directly to the shaft of the gas turbine (either the gas
generator or power turbine). Usually only one or two accessories are
direct connected. In most cases it is one of the lubrication pumps that
is direct connected.
Indirect drives utilize electric, steam, or hydraulic motors for
power. Using indirect drives also facilitates employing redundant systems,
thus increasing the system and the gas turbine plant reliability.
Electric systems that are powered by a directly driven electric
generator share the advantages of both the direct and indirect drive
arrangements.
STARTING SYSTEM 1,2
Starting systems fall into two categories: those that drive the gas
generator directly and those that drive the gas generator through an
intermediate gearbox. Starters may be diesel or gas engine, steam or
gas turbine, electric, hydraulic, or pneumatic (air or gas). The starter
satisfies two independent functions: the first is to rotate the gas generator
until it reaches its self-sustaining speed, and the second is to
drive the gas generator compressor to purge the gas generator and
the exhaust duct of any volatile gases prior to initiating the ignition
cycle. The starting sequence consists of the following:
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