Chapter 4 Flashcards
A disadvantage when a gas turbine is operated at peak power is:
A) Maximum power is obtained
B) It satisfies the peak electrical load demand
C) Increased maintenance costs
D) Turbine efficiency remains unchanged
E) Too much electricity is produced
C
The beneficial effect of intercoolers decreases:
A) When pressure ratio increases
B) When combining with regeneration
C) With higher air throughput
D) With smaller sized turbines
E) With colder cooling water
A
The performance of a gas turbine is determined by comparing:
A) The turbine efficiency
B) Gas flow in versus kWh out
C) Gas flow in versus power output
D) Heat rate versus power output
E) Gas flow and pressure in versus power output
D
Auxiliary systems on gas turbines are needed to:
- Provide fuel at the proper temperature and pressure
- Clean and treat fuels
- Provide hydraulic fluid for bearing lubrication
- Inject steam to clean the ducts and housing
- Provide anti-icing
A) 3, 4, 5
B) 1, 2, 3
C) 2, 3, 4
D) 1, 2, 5
E) 2, 4, 5
D
The term, “closed cycle” means:
A) The compressor outlet is closed and the inlet is open
B) The regenerator is not open on either side
C) The combustion chamber is heated internally
D) The turbine exhaust gases are not open to atmosphere
E) The combustion chamber is heated externally
D
The air bypassing the combustors is used for:
A) Cooling the turbine blades
B) Ensuring enough air for complete combustion
C) Increasing the mass of gas products flowing
D) Raising the combustion efficiency
E) Raising the product temperatures flowing into the turbine blades
A
Crossover tubes are used to ensure combustor cans:
A) Operate at lower temperatures
B) Are aligned vertically
C) Are able to withstand thermal stresses
D) Operate at the same pressure
E) Do not move, thus reducing leaks
D
The typical maximum runtime before blade replacement is:
A) 75 000 hours
B) 125 000 hours
C) 50 000 hours
D) 150 000 hours
E) 100 000 hours
E
In dual shaft gas turbines, the load is driven by:
A) The low pressure turbine
B) The starting motor and low pressure turbine
C) The output shaft from the compressor
D) The exhaust gases from the combustion chamber
E) The high pressure turbine
A
The term, “open cycle” means:
A) The working fluid is drawn from and returned to the atmosphere
B) The turbine exhaust is open to atmosphere
C) The compressor inlet is open to atmosphere
D) For every cycle, the inlet and outlet are open
E) The compressor outlet is open to the combustion chambers
A
Regenerators are installed between:
A) The combustors and HP turbine sections
B) The HP compressor and the combustor sections
C) The LP and the HP turbine sections
D) The LP and the HP compressor sections
E) The outlet and the LP turbine sections
B
Power is developed in a gas turbine by:
A) Attaching a generator to the turbine
B) Expanding the gases through the turbine blades
C) Decreasing the hot gas temperature and pressure
D) Changing velocity to pressure to drive the turbine blades
E) Changing pressure to velocity to drive the turbine blades
B
A disadvantage of a can combustor is:
A) Non uniform temperatures are experienced
B) An efficient use of space
C) Low flow resistance
D) Multiple ignitors are used
E) Low pressure operation
D
Reducing gears on gas turbines are used to:
A) Match turbine and generator speeds
B) Increase horsepower
C) Drive slower hydraulic pumps
D) Drive slower lube oil pumps
E) Control speeds
A
The purpose of a compressor diffuser is to convert:
A) The compressed air exiting the casing
B) The high pressure air into velocity for the casing
C) The compressed air exiting the impellor
D) The high velocity air to pressure energy
E) High velocity air to high pressure
D
