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3B2 > Ch. 4 > Flashcards

Ch. 4 Flashcards

1
Q
  1. The gas turbine system is:

a. Ideal for large generator systems
b. Ideal to be used over a steam turbine
c. Ideal to be used for unmanned and remote locations
d. Ideal for all applications of a process plant
e. Ideal for large gas plant

A

C. Ideal to be used for unmanned and remote locations

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2
Q
  1. Gas turbines are used in industry as prime movers for:
1)     Portable generators
2)     Fire pumps
3)     Air compressors
4)     Emergency equipment

a. 1, 2, 3
b. 1, 2, 4
c. 1, 3, 4
d. 1, 2, 3, 4
e. 2, 3, 4

A

D. 1, 2, 3, 4

1) Portable generators
2) Fire pumps
3) Air compressors
4) Emergency equipment

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3
Q
  1. Gas turbine units are used:
1)     For electrical generation
2)     Where energy is produced for process plants
3)     Where waste gases from the process may be used to drive the gas turbine
4)     Where high thermal efficiency is required

a. 1, 2, 3
b. 1, 3, 4
c. 2, 3, 4
d. 1, 2, 3, 4
e. 1, 2, 4

A

A. 1, 2, 3

1) For electrical generation
2) Where energy is produced for process plants
3) Where waste gases from the process may be used to drive the gas turbine

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4
Q
  1. Gas turbines are used in large power plants to provide almost instant emergency power for:

a. Peak load shaving
b. High heating load
c. Water pumps
d. Exit lighting
e. Essential services

A

E. Essential services

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5
Q
  1. Some of the characteristics which make the gas turbine a better choice over other prime movers are:
1)     Low maintenance
2)     Minimum cooling water required
3)     High thermal efficiency
4)     Rapid start up and loading

a. 1, 2, 3
b. 1, 2, 4
c. 1, 3, 4
d. 2, 3, 4
e. 1, 2, 3, 4

A

B. 1, 2, 4

1) Low maintenance
2) Minimum cooling water required
4) Rapid start up and loading

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6
Q
  1. Gas turbines are far superior to other types of engines in their:

a. Fuel consumption
b. Efficiency
c. Lubricating oil consumption
d. Power per mass ratio
e. Fuel usage

A

D. Power per mass ratio

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7
Q
  1. A closed cycle gas turbine system:

a. Does not use a starting motor
b. Has lower pressure used in system
c. Will use the same working fluid over again
d. Must use a cooler before the regeneration
e. Has a lower initial cost than that of the open cycle gas turbine

A

C. Will use the same working fluid over again

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8
Q
  1. The compressor on a gas turbine:

a. Can be driven by the load turbine
b. Is always of the axial type
c. Is always a multi-stage compressor
d. Can be of the reciprocating type
e. Is always of the centrifugal type

A

A. Can be driven by the load turbine

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9
Q
  1. In a dual shaft gas turbine arrangement:

a. The load turbine is down stream from the compressor turbine
b. The load turbine drives the prop on a turbo prop engine
c. Is always used in an open cycle
d. System flexibility is reduced
e. A larger starting motor is required

A

A. The load turbine is down stream from the compressor turbine

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10
Q
  1. The advantages of a dual shaft gas turbine arrangement are:
1)     Greater flexibility
2)     It is cheaper
3)     Smaller starting motor may be used
4)     High pressures and temperatures may be obtained

a. 1, 2
b. 1, 3
c. 2, 3
d. 2, 4
e. 1, 4

A

b. 1, 3

1) Greater flexibility
3) Smaller starting motor may be used

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11
Q
  1. In a gas turbine cycle using an intercooler the following advantages are obtained:
1)     The specific volume of the air is reduced
2)     The cooler air recovers more heat from the regenerator
3)     The temperature of the second stage compressor will be increased thus increasing thermal efficiency
4)     More of the turbine power can be available for the output load

a. 1, 2, 3
b. 1, 2, 4
c. 1, 3, 4
d. 2, 3, 4
e. 1, 2, 3, 4

A

B. 1, 2, 4

1) The specific volume of the air is reduced
2) The cooler air recovers more heat from the regenerator
4) More of the turbine power can be available for the output load

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12
Q
  1. The advantages of using a reheater in a gas turbine cycle are:
1)     More air can be compressed
2)     A small combustor may be used
3)     Less air will have to be compressed in order to do the same amount of work
4)     The thermal efficiency of the cycle will be improved

a. 1, 3
b. 1, 4
c. 2, 3
d. 2, 3
e. 3, 4

A

E. 3, 4

3) Less air will have to be compressed in order to do the same amount of work
4) The thermal efficiency of the cycle will be improved

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13
Q
  1. The purpose of a regenerator in a gas turbine is:

a. To clean the exhaust gases
b. To improve the efficiency of the turbine
c. To decrease the temperature in the combustion chamber
d. To raise the air temperature before compression
e. To decrease the air temperature after compression

A

B. To improve the efficiency of the turbine

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14
Q
  1. The regenerator in a gas turbine cycle is located:

a. Between the power and load turbine
b. Between the turbine outlet and compressor inlet
c. Between the compressor and combustor
d. Between the combustor and turbine
e. Between the power turbine and generator

A

C. Between the compressor and combustor

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15
Q
  1. The regenerator of a gas turbine cycle is a:

a. Second combustor
b. Heat exchanger
c. Vessel used to transfer heat from the exhaust gas to the working fluid before compression occurs
d. Increase the pressure of the working fluid in the system
e. Increase the temperature of the combustor’s outlet

A

B. Heat exchanger

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16
Q
  1. A gas turbine air compressor with an intercooler:

a. Has the intercooler located after the compressor
b. Increases the volume of air being supplied
c. Allows more output at the turbine
d. Used only with axial type compressors
e. Are not as efficient

A

C. Allows more output at the turbine

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17
Q
  1. The combustion chamber of a gas turbine:

a. Increases the pressure of the compressed air
b. Burns fuel with excess air
c. Is located between the load turbine and the compressor turbine
d. Is always of the multiple burner type
e. Utilizes 70 % of the air supplied by the compressor for actual combustion process

A

B. Burns fuel with excess air

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18
Q
  1. A gas turbine combustion chamber requires:

a. A cooling water jacket on the inner canister
b. A vacuum breaker
c. A safety pressure relief device
d. A high voltage ignition plug for initial ignition
e. An annual hydrostatic test

A

D. A high voltage ignition plug for initial ignition

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19
Q
  1. The capacity of a gas turbine will increase in cold weather because:

a. High grades of fuel oil burn better at cooler temperatures
b. The density of the air is increased
c. The volume if the air will increase
d. The temperature drop throughout the cycle will be less
e. The atmospheric pressure will increase

A

B. The density of the air is increased

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20
Q
  1. Which of the following are advantages of a gas turbine:
1)     Simple design
2)     Low cost
3)     Minimal manpower
4)     Maximum outage time
5)     Rapid starting

a. 1, 2, 3, 4
b. 2, 3, 4, 5
c. 1, 3, 4, 5
d. 1, 2, 3, 5
e. 1, 2, 4, 5

A

D. 1, 2, 3, 5

1) Simple design
2) Low cost
3) Minimal manpower
5) Rapid starting

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21
Q
  1. Which of the following are disadvantages of a gas turbine?
1)     Complicated design
2)     High manufacturing costs
3)     Slow response to load change
4)     Low efficiency 
5)     Suitable for low power applications

a. 1, 3, 5
b. 2, 3, 4
c. 3, 4, 5
d. 1, 4, 5
e. 1, 2, 3

A

E. 1, 2, 3

1) Complicated design
2) High manufacturing costs
3) Slow response to load change

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22
Q
  1. The term peaking gas turbine refers to:

a. Gas turbines that produce max power
b. Gas turbines used with peak horsepower
c. Gas turbines used during major outages
d. Gas turbines used every day
e. Gas turbines used in heavy load situations

A

E. Gas turbines used in heavy load situations

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23
Q
  1. Industrial gas turbines compared to aero-derivative turbines are:

a. Light weight
b. Rapid load changers
c. Less efficient
d. Use all different fuels
e. Fast starting

A

C. Less efficient

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24
Q
  1. In simple gas turbines the air is compressed to the following maximum pressures:

a. 2000 kPa
b. 2500 kPa
c. 3000 kPa
d. 3500 kPa
e. 4000 kPa

A

C. 3000 kPa

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25
Q
  1. Gas turbine final combustion temperatures in a simple gas turbine are:

a. 1500ºC
b. 1700ºC
c. 1800ºC
d. 2000ºC
e. 2200ºC

A

D. 2000ºC

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26
Q
  1. Gas Temperatures at the simple gas turbine inlet section are at maximum:

a. 580ºC
b. 770ºC
c. 875ºC
d. 920ºC
e. 1050ºC

A

D. 920ºC

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27
Q
  1. Gas Temperatures at the exhaust of a simple gas turbine are at maximum:

a. 500°C
b. 540°C
c. 760°C
d. 680°C
e. 640°C

A

E. 640°C

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28
Q
  1. Aero-derivative engines are aircraft jet engines that:

a. Are converted from a turbo prop engine
b. Are heavier in construction than a jet engine
c. Are closer in design to industrial gas turbines
d. Are more rapid in their startup than jet engines
e. Use less power turbine blades

A

A. Are converted from a turbo prop engine

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29
Q
  1. In dual shaft Gas Turbines the load is driven by:

a. The high pressure turbine
b. The starting motor and low pressure turbine
c. The low pressure turbine
d. The exhaust gases from the combustion chamber
e. The output shaft from the compressor

A

C. The low pressure turbine

30
Q
  1. The term open cycle means:

a. The compressor inlet is open to atmosphere
b. The compressor outlet is open to the combustion chambers
c. The turbine exhaust is open to atmosphere
d. The working fluid is drawn from and returned to the atmosphere
e. Every cycle the inlet and the outlet are open

A

d. The working fluid is drawn from and returned to the atmosphere

31
Q
  1. What part of the gas turbine is normally smaller in dual shaft Gas Turbines:

a. The load
b. The combustion chambers
c. The starting motor
d. The compressor
e. The turbine blades

A

c. The starting motor

32
Q
  1. Closed cycle means:

a. Compressor outlet is closed and the inlet is open
b. Combustion chamber is heated internally
c. Combustion chamber is heated externally
d. The regenerator is not open on either side
e. The exhaust gases are not open to atmosphere

A

e. The exhaust gases are not open to atmosphere

33
Q
  1. An advantage of Closed cycle is:

a. Cooling water lowers cost
b. Fuel is cheaper
c. Working fluid supports combustion
d. Pressures are lower so stress is lower on all the equipment
e. Complexity is less

A

a. Cooling water lowers cost

34
Q
  1. Exhaust systems are required on Gas Turbines to:
1)     Allow the installation of silencers
2)     Allow the installation of heat recovery equipment
3)     Direct the flow to heat recovery systems
4)     Minimize power losses
5)     Protect operators

a. 1, 3, 5
b. 1, 2, 3
c. 3, 4, 5
d. 1, 4, 5
e. 1, 3, 4

A

b. 1, 2, 3

1) Allow the installation of silencers
2) Allow the installation of heat recovery equipment
3) Direct the flow to heat recovery systems

35
Q
  1. Gas Turbines enclosures are used to:
1)     Protect equipment from the elements
2)     Allows the incorporation of heat and gas detectors
3)     Contains the gas turbine DCS controls 
4)     Keep the turbine from cooling down, more efficient
5)     Provides ventilation systems

a. 1, 2, 3
b. 1, 2, 5
c. 2, 3, 4
d. 2, 3, 5
e. 3, 5, 1

A

b. 1, 2, 5

1) Protect equipment from the elements
2) Allows the incorporation of heat and gas detectors
5) Provides ventilation systems

36
Q
  1. Auxiliary systems on Gas Turbines are needed to:
1)     Provide fuel at the proper temperature and pressures
2)     Clean and treat fuels
3)     Provide hydraulic fluid for bearing lubrication 
4)     Inject steam to clean the ducts and housing
5)     Provide anti-icing

a. 1, 2, 3
b. 2, 3, 4
c. 3, 4, 5
d. 1, 2, 5
e. 2, 4, 5

A

d. 1, 2, 5

1) Provide fuel at the proper temperature and pressures
2) Clean and treat fuels
5) Provide anti-icing

37
Q
  1. Reducing gears on gas turbines are used:

a. To control speeds
b. To drive slower lube oil pumps
c. To drive slower hydraulic pumps
d. To match turbine and generator speeds
e. To increase horsepower

A

d. To match turbine and generator speeds

38
Q
  1. Advantages of gas turbines intakes are:
1)     Remove contaminants
2)     Prevent damage from foreign objects
3)     Allow addition of special cooling systems
4)     Smooth air flow into the compressor
5)     Decrease the velocity of the incoming air

a. 1, 2, 3, 4
b. 2, 3, 4, 5
c. 3, 4, 5, 1
d. 4, 5, 1, 2
e. 5, 1, 2, 3

A

a. 1, 2, 3, 4

1) Remove contaminants
2) Prevent damage from foreign objects
3) Allow addition of special cooling systems
4) Smooth air flow into the compressor

39
Q
  1. Gas Turbines are rated by:

a. Output shaft power output vs. fuel energy rate
b. Power produced at the output shaft
c. Horsepower
d. Ratio of rated power to the fuel energy rate
e. Ratio of rated power to the LHV of the fuel

A

b. Power produced at the output shaft

40
Q
  1. Improving gas turbine efficiency is done by:
1)     Regeneration
2)     Precooling
3)     Aftercooling
4)     Intercooling
5)     Reheating

a. 1, 2, 3
b. 2, 3, 4
c. 3, 4, 5
d. 4, 5, 1
e. 1, 2, 5

A

d. 4, 5, 1

4) Intercooling
5) Reheating
1) Regeneration

41
Q
  1. Regenerators are installed:

a. Between the Lp and the Hp compressor sections
b. Between the Lp and the Hp turbine sections
c. Between the outlet and the LP turbine sections
d. Between the hp compressor and the combustor sections
e. Between the combustors and the Hp turbine sections

A

c. Between the outlet and the LP turbine sections

42
Q
  1. The beneficial effect of intercoolers decreases with:

a. Combining with regeneration
b. Pressure ratio increase
c. Colder cooling water
d. Smaller sized turbines
e. Higher air throughput

A

b. Pressure ratio increase

43
Q
  1. Reheat is accomplished by:

a. Expanding and heating the gases in two stages
b. Heating the gases after the Lp compressor section
c. Heating the gases between the Hp and Lp turbine
d. Heating the air between the Lp and Hp compressor stages
e. Heating the air between the Hp compressor and the Hp turbine sections

A

c. Heating the gases between the Hp and Lp turbine

44
Q
  1. How much of the energy provided by the fuel, is absorbed by the compressor:

a. Up to 2/3
b. Up to 1/3
c. Up to 1/2
d. Up to 3/4
e. Up to ¼

A

a. Up to 2/3

45
Q
  1. The purpose if a compressor diffuser is to:

a. Convert the compressed air exiting the casing
b. Convert the compressed air exiting the impellor
c. Convert the high pressure air into velocity for the casing
d. Convert the high velocity air to pressure energy
e. Convert high velocity air to high pressure

A

d. Convert the high velocity air to pressure energy

46
Q
  1. The advantages of centrifugal over axial compressors are:
    ,
    1) High capacity
    2) Short length
    3) High flow rates
    4) Strength
    5) Adjustable flow

a. 1, 2
b. 2, 3
c. 3, 4
d. 4, 5
e. 2, 4

A

e. 2, 4

2) Short length
4) Strength

47
Q
  1. In axial flow compressors, compression occurs by:

a. Adjusting the stationary blades
b. Adjusting the rotating blades
c. Adjusting both stationary and rotating blades
d. The use of nozzle blocks between stages
e. Adjusting only the moving blades

A

c. Adjusting both stationary and rotating blades

48
Q
  1. In the combustors, how much air is utilized for fuel combustion:

a. 0.1
b. 0.2
c. 0.3
d. 0.4
e. 0.5

A

b. 0.2

49
Q
  1. In the combustors, how much air bypasses the combustion chambers:

a. 0.9
b. 0.8
c. 0.7
d. 0.6
e. 0.5

A

b. 0.8

50
Q
  1. The air bypassing the combustors is used for:

a. Increasing the mass of gas products flowing
b. Ensuring enough air for complete combustion
c. Raising the product temperatures flowing into the turbine blades
d. Raising the combustion efficiency
e. Cooling the turbine blades

A

e. Cooling the turbine blades

51
Q
  1. The combustion chamber exit gas temperatures will reach a maximum of:

a. 1550°C
b. 1570°C
c. 1650°C
d. 1670°C
e. 1750°C

A

d. 1670°C

52
Q
  1. The turbine exits gas temperatures will be a maximum of:

a. 600°C
b. 700°C
c. 750°C
d. 800°C
e. 850°C

A

b. 700°C

53
Q
  1. Large volume combustors are used when:

a. Simplicity is required
b. Frontal area is no concern
c. A regenerator is being used
d. Less complicated design is called for
e. Air flow path is less convoluted

A

c. A regenerator is being used

54
Q
  1. The advantage of the Can-Annular design is:

a. Uniform outlet temperatures
b. Multiple ignitors ensure combustion
c. Fuel lines distribute fuel more rapidly
d. Is a more efficient use of space
e. If one can quits the others will keep working

A

a. Uniform outlet temperatures

55
Q
  1. In a single can combustor the interconnected tubes:

a. Decreases the number of ignitors used
b. Decreases the number injectors required
c. Decreases the complexity of the turbine
d. Decreases the pressures differences in each tube
e. Decreases the number of flame tubes required

A

d. Decreases the pressures differences in each tube

56
Q
  1. Power is extracted in a gas turbine by:

a. Expanding the gases through the turbine blades
b. Attaching a generator to the turbine
c. Changing pressure to velocity to drive the turbine blades
d. Changing velocity to pressure to drive the turbine blades
e. Decreasing the hot gas temperature and pressure

A

e. Decreasing the hot gas temperature and pressure

57
Q
  1. There are fewer turbine blades than compressor blades because:

a. Energy can be extracted more efficiently
b. Turbine blades are bigger so require fewer
c. Higher exhaust temperatures can be tolerated
d. The hot gases occupy more volume
e. Hot exhaust gases are required for the HRSG’s

A

a. Energy can be extracted more efficiently

58
Q
  1. Gas turbine blades are cooled to:

a. Increase power output to the HRSG
b. Increase metal temperatures out of the turbine
c. Increase the longevity of the blades
d. Increase flow rates through each section
e. Cool the temperatures going into the next section

A

c. Increase the longevity of the blades

59
Q
  1. The greatest limitation on increased turbine output is:

a. Turbine blade configurations
b. Heat resisting steels
c. Design limitations of the turbine shafts
d. Casing designs that allow flexing
e. Cost of expensive fuels

A

b. Heat resisting steels

60
Q
  1. The maximum run time before blade replacement is:

a. 75,000 hours
b. 100,000 hours
c. 150,000 hours
d. 125,000 hours
e. 50,000 hours

A

b. 100,000 hours

61
Q
  1. Control of a gas turbine is accomplished by:

a. Varying the loading station
b. The power turbine all speed governor
c. Varying load on the generator
d. Varying the fuel flow
e. Controlling the shaft speed

A

d. Varying the fuel flow

62
Q
  1. Automatic emergency trips shut off the main fuel valve in the event of:

a. High exhaust temperatures
b. Differential pressures are too high across the filters
c. Inlet air temperatures exceed maximum
d. Compressor discharge pressures are too high
e. Compressor discharge temperatures are too high

A

a. High exhaust temperatures

63
Q
  1. Vibration accelerometers are used:

a. If journal or tilt pad bearings are used
b. To trip the turbine on rapid acceleration
c. To control the ramp speed on startup
d. On large industrial gas turbines
e. For anti-friction bearings

A

e. For anti-friction bearings

64
Q
  1. Protective devices will shutdown the turbine if:

a. Lube oil pressure is too high
b. Governor oil pressure is too low
c. Compressor air flow is too high
d. Combustor gas temperature is too low
e. Exhaust gas temperature is too high

A

e. Exhaust gas temperature is too high

65
Q
  1. Operators are allowed too control______________.

a. the air ratios to the combustors
b. the turbine speeds
c. the burner logic for the combustors
d. the turbine ramp rates for start up
e. the shut down sequencing

A

b. the turbine speeds

66
Q
  1. The performance of a gas turbine is calculated by________________.

a. the turbine efficiency
b. heat rate vs. power output
c. gas flow in vs. kWh out
d. gas flow in vs. power output
e. gas flow and pressure in vs. power output

A

b. heat rate vs. power output

67
Q
  1. The number one factor limiting turbine efficiency increases is________________________.

a. the blade metallurgy
b. the low compressor discharge pressures
c. the blade design configuration
d. the compression ratio
e. the reduction of pressure losses

A

d. the compression ratio

68
Q
  1. Turbine inlet air temperature __________________.

a. increases the work done by the turbine
b. decreases the amount of fuel used for the same output
c. decreases the mass of gas flow in the turbine
d. improves overall combustion in the combustors
e. increases the power output of the compressor section

A

c. decreases the mass of gas flow in the turbine

69
Q
  1. Maximum power achieved by a gas turbine is a function of______________________.

a. the number of turbine stops and starts every year
b. the number of times base load power output is exceeded
c. the number of times peak load is obtained in a year
d. the number of times operational limits are exceeded
e. life expectancy of hot gas components

A

e. life expectancy of hot gas components

70
Q
  1. The operating output of a gas turbine is effected the most by _________________________.

a. changing inlet air temperature
b. changing the heat valve of the fuel
c. changing the gas pressure to the combustors
d. changing the combustion flame pattern
e. changing from base loading to peak loading

A

a. changing inlet air temperature

3B2 (15 decks)

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