A gas turbine compressor is usually
centrifugal type
downstream of the turbine
dynamic axial design
downstream of the combustor
driven by a motor
The compressor on the gas turbine
can be driven by the load turbine
is always of the axial type
is always a multi-staged compressor
is always independently driven
is always a reciprocating type
The combustion chamber of a gas turbine
increases the pressure of the compressed air
is heated between the load turbine and the compression turbine
burns fuel with excess air
is water cooled
rotates at shaft speed
Many typical steam plant auxiliaries are eliminated with a gas turbine due to its
small size
high speed
high power to weight ratio
simplicity
low oil consumption
Gas turbines are very popular where
noise does not present a problem
water is scarce
industrial sites are small and in congested areas
thermal pollution is of major concern
natural gas is plentiful
gas turbines are ideal when considering
long warm-up periods
emergency power generation
automotive power
cooling water pump operation
good thermal efficiency
A two shaft gas turbine
has the load turbine downstream from the compressor turbine
has the first turbine drive the prop on a turbo-prop engine
is always an open cycle type
is always a closed cycle type
does not require a starting motor
A gas turbine is not self-starting. It must be rotated at _________ of its maximum speed before fuel is turned on
10% to 30 %
15% to 30 %
20% to 30 %
25% to 30 %
25% to 50%
Early gas turbines were handicapped by
metal not being able to withstand high speed centrifugal forces
the inability to get enough air into the combustion chamber
metals not standing the high temperatures involved
their high operating speeds
their inadequate power capability
The temperature to which the air can be raised at the turbine inlet is
an indication of a units power
directly related to the units size
a function of the air compressor input
an indication of the units efficiency
important for proper compressor performance
The low installation cost of a gas turbine is
due to cheap materials in the blades
due to short fuel lines
because no fuel pump is required
because no electrical wiring is required
because less auxillary equipment is needed
