Ch. 5 Flashcards
- Lube oil systems provide two basic functions.
a. Filtration and antifriction.
b. Lubricating sliding surfaces in the bearings and cool the bearings.
c. An adequate supply of oil to machinery and cooling machine parts.
d. Filtration and lubricate sliding surfaces.
e. Vibration dampening and cooling the bearings.
b. Lubricating sliding surfaces in the bearings and cool the bearings.
- All major oil systems consist of what basic components?
1) An oil reservoir to ensure an adequate supply of oil 2) Filters to ensure the oil is clean 3) Pumps to provide pressure 4) Coolers to ensure oil temperatures are kept within operating limits 5) Protective, monitoring and control devices
a. 1, 2, 3, 4
b. 1, 2, 5
c. 1, 2, 3, 4, 5
d. 1, 5
e. 5
c. 1, 2, 3, 4, 5
1) An oil reservoir to ensure an adequate supply of oil
2) Filters to ensure the oil is clean
3) Pumps to provide pressure
4) Coolers to ensure oil temperatures are kept within operating limits
5) Protective, monitoring and control devices
- Gas turbines use what two different types of bearings?
1) Antifriction (roller and/or ball) bearings 2) Radial (journal or tilt-pad) bearings 3) Axial (spherical) bearings 4) Take-up (frame) bearings 5) Swing (levered) bearings
a. 1, 4
b. 1, 2
c. 1, 3
d. 2, 4
e. 4, 5
b. 1, 2
1) Antifriction (roller and/or ball) bearings
2) Radial (journal or tilt-pad) bearings
- Why is natural gas the best fuel for a gas turbines?
a. It promotes the most efficient combustion and produces the lowest environmental emissions.
b. It is less expensive than other fuel sources.
c. It has the highest efficiency of combustion.
d. It has less contaminants as compared to other fuels sources.
e. It is a lower explosion risk than other fuels.
a. It promotes the most efficient combustion and produces the lowest environmental emissions.
- Routine maintenance on a gas turbine should involve checking for fuel leaks on a __________ basis.
a. yearly
b. monthly
c. weekly
d. daily
e. hourly
d. daily
- An essential auxiliary in a gas turbine installation is:
a. A generator
b. A reheater
c. A starting motor
d. An air heater
e. A water pump
c. A starting motor
- Introducing warm air into the gas turbine intake as a result of an anti-icing system will?
a. Reduce the capacity of the unit, because warm air is less dense than cold air.
b. Form ice in the air intake.
c. Cause major damage resulting in catastrophic destruction of the compressor section blading.
d. Bleed air from the compressor.
e. Increase hot turbine exhaust.
a. Reduce the capacity of the unit, because warm air is less dense than cold air.
- What is the final step in the sequence of starting a Gas Turbine?
a. Preparation for startup
b. Loading
c. Warmup
d. Crank and lightoff
e. Start initiation
b. Loading
- What is the first step in the normal shutdown of a gas turbine?
a. Reduce the speed to idle so the gas turbine can cool down.
b. Open the breaker that connects the generator to the power system.
c. Close the fuel valve.
d. Stop the rotor.
e. Stop the lube oil system.
a. Reduce the speed to idle so the gas turbine can cool down.
- In order to keep the gas pass of a gas turbine clean the following must be done:
1) Inspect and clean air intake filters 2) Water washing of compressor blades 3) Inspect and clean air intake ducts 4) Good quality fuel must be used
a. 1, 2
b. 1, 3
c. 1, 2, 3
d. 1, 2, 3, 4
e. 1, 3, 4
d. 1, 2, 3, 4
1) Inspect and clean air intake filters
2) Water washing of compressor blades
3) Inspect and clean air intake ducts
4) Good quality fuel must be used
- Why do microturbines require only air bearings:
1) No governing oil system 2) Small overall size 3) Simplicity of components 4) Everything on one shaft 5) No oil systems
a. 1, 2
b. 2, 3
c. 2, 5
d. 3, 4
e. 4, 5
c. 2, 5
2) Small overall size
5) No oil systems
- Most aero derivative turbines lube oil systems require?
a. Two back lube oil pumps
b. Separate inlet and outlet filter systems
c. Separate lube oil tanks and coolers
d. Separate lube oil systems
e. Separate back up pumps
d. Separate lube oil systems
- Thrust bearings on dual shaft gas turbines are positioned:
a. At the front of the compressor and next to the turbine bearing.
b. At the front of both the compressor and the turbine section.
c. At the back of both the compressor section and the turbine section.
d. At the back of the compressor and next to the turbine bearing.
e. At the front and back of the turbine section.
a. At the front of the compressor and next to the turbine bearing.
- Tilt pad bearings are used:
1) In aero-derivative gas turbines 2) According to the manufacturers specifications 3) On duel shaft industrial gas turbines 4) In large industrial gas turbines 5) With pivot pins
a. 1, 2
b. 2, 3
c. 3, 4
d. 4, 5
e. 5, 1
d. 4, 5
4) In large industrial gas turbines
5) With pivot pins
- Aero-derivative lube oil systems use a scavenge pump to:
a. Recycle oil form the cleaning system
b. Collects oil from all users for recycling
c. Siphons off small amounts of oil for cleaning
d. Collects oil from the supply and return filters for cleaning
e. Returns the oil from the bearings to the supply
e. Returns the oil from the bearings to the supply
- Natural gas is the best fuel for gas turbines because:
1) No onsite storage 2) Most efficient combustion 3) Simplest control system 4) Highest heat value 5) Cleanest burning
a. 1, 3
b. 2, 4
c. 3, 5
d. 2, 5
e. 2, 3
d. 2, 5
2) Most efficient combustion
5) Cleanest burning
- A fuel gas compressor must be used on gas turbines if?
a. The complexity of the gas system reduces the gas pressure to low
b. The gas supply pressure is less than the compressor last stage pressure
c. The total pressure drop across the combustors is too great
d. Multiple gas nozzles drops the burner gas pressure too low
e. The combustor outlet pressure is greater the compressor outlet pressure
b. The gas supply pressure is less than the compressor last stage pressure
- The most important component of a fuel metering system is?
a. Fuel gas Hi/Lo pressure switches
b. Duplex filters/separators
c. Fuel metering valve
d. Primary and secondary shut off valves
e. Fuel gas scrubber
c. Fuel metering valve
- The use of a low heating value (LHV) fuel requires:
a. Special nozzles and combustors
b. Higher pressure gas supply
c. Higher pressure gas compressors
d. Higher pressures from the compressor
e. Larger bore piping for high flow rates
a. Special nozzles and combustors
- Typical fuel gas metering valves are:
a. Pneumatically actuated
b. A type of pneumatic gas metering control valve
c. Hydraulically actuated
d. Electro-pneumatically actuated
e. Becoming electrically actuated
e. Becoming electrically actuated
- Gas Turbines use duel fuels for:
1) Consistent power delivery 2) Use as backup 3) Increasing overall power output 4) Switching to cheaper fuels 5) Less complicated controls during operation
a. 1, 2
b. 2, 3
c. 2, 4
d. 3, 4
e. 4, 5
c. 2, 4
2) Use as backup
4) Switching to cheaper fuels
- Fuel system daily maintenance checks consist of:
1) Checking the treatment components 2) Checking for fuel leaks 3) Checking fuel pressures and temperatures 4) Checking Delta P across the filters 5) Checking the protective devices
a. 1, 2
b. 2, 3
c. 3, 4
d. 2, 4
e. 3, 5
b. 2, 3
2) Checking for fuel leaks
3) Checking fuel pressures and temperatures
- The most important requirement in a Duel fuel system is:
a. Two types of fuels
b. Ability to burn both fuels together
c. A complex control system
d. Proper design of the combustors
e. Special fuel nozzles
e. Special fuel nozzles
- Fuel treatment systems consist of :
a. Centrifuges, filters , strainers , pumps and related instrumentation
b. Filters, dewatering and chemical treatment
c. Centrifuges, filters, dewatering and chemical treatment
d. Dewatering and chemical treatment
e. Mechanical and chemical treatment
c. Centrifuges, filters, dewatering and chemical treatment
- Chemicals harmful to the turbine section are:
a. Calcium, magnesium and phosphate
b. Calcium, potassium and silica
c. Potassium, calcium and magnesium
d. Sodium, vanadium and silica
e. Sodium, potassium, and vanadium
e. Sodium, potassium, and vanadium
- Two ways to decrease NOx are:
1) Lower the combustion temperature 2) Use staged air in the combustors 3) Utilize special burners 4) Decrease the fuel to air ratio 5) Operate with a lean fuel mixture
a. 1, 2
b. 2, 3
c. 2, 4
d. 4, 5
e. 3, 5
d. 4, 5
4) Decrease the fuel to air ratio
5) Operate with a lean fuel mixture
- The main disadvantage to water or steam injection is:
a. Reduced thermal efficiency
b. Corrosion of the rotating blades
c. Corrosion of the stationary blades
d. Corrosion of hot section components
e. Require ultra-pure water or steam
a. Reduced thermal efficiency
- Dry low NOx combustion systems operate on:
a. Staged fuel burning
b. Lean premixed combustion
c. Bypass air cooling the flame temperature
d. Alternating the spray patterns of the burners
e. Injection of dry scrubbing compounds
b. Lean premixed combustion
- Control of the dry low NOx burners is done by:
a. Adjustable flow nozzles
b. Rotating fuel nozzles
c. Using three gas headers to inject the fuel
d. Extensive solenoid gas staging system
e. Computer controlled fuel staging valves
d. Extensive solenoid gas staging system
- The practical limit for NOx with steam or water injection for natural gas is:
a. 5 ppm
b. 10 ppm
c. 15 ppm
d. 20 ppm
e. 25 ppm
e. 25 ppm
- The practical lower limit for NOx for liquid fuels is:
a. 22 ppm
b. 32 ppm
c. 42 ppm
d. 52 ppm
e. 62 ppm
c. 42 ppm
- Starter systems are disengaged when the turbine shaft reaches:
a. Once the shaft speeding up
b. Once the turbine speed overruns the starting motor
c. 30% speed
d. 50% rated speed
e. Fuel is ignited
e. Fuel is ignited
- Which device is not used to start a gas turbine:
a. Small gas engines
b. Small diesel engines
c. Pneumatic starters
d. Electric motors
e. Steam turbine expanders
a. Small gas engines
- Remote gas pipeline stations use___________ for starting gas turbines.
a. small gas engines
b. small diesel engines
c. pipeline gas
d. compressed air tugger motors
e. electro-hydraulic motors
c. pipeline gas
- Turning gears are used to:
a. Rotate the shaft every hour
b. Rotate the shaft 90 degrees every hour
c. Lower the stress on the starting motor
d. Prevent the shaft from locking
e. Prevents the shaft developing flat spots
d. Prevent the shaft from locking
- Turning gears require:
a. Extensive cooling systems
b. Warm up and cool down on usage
c. A method to engage and or disengage the shaft
d. Variable frequency drive motors
e. Hydraulic coupling
c. A method to engage and or disengage the shaft
- The first piece on an air intake system is:
a. Mesh screen
b. Cooling coils
c. Heating coils
d. Guard filter
e. Drift eliminators
a. Mesh screen
- The air intake duct is mounted above the gas turbine enclosure to:
a. Lower the inlet air flow resistance
b. Keep the intake duct a short as possible
c. Make the enclosure more compact
d. Provide support for the filters
e. Place it in cleaner air
e. Place it in cleaner air
- Inlet air temperatures to the gas turbine are reduced by:
a. Spray cooling
b. Fog cooling
c. Evaporative pads
d. Evaporative cooling
e. Refrigeration coils
d. Evaporative cooling
- Anti-icing systems are used to prevent:
a. Plugging of filters with ice
b. Damage to the duct work from icing
c. Blade damage
d. Too low an intake air temperature
e. Compressor surging
c. Blade damage
- Anti-icing systems can cause:
a. Wetting of the paper filter elements
b. Lowering of the unit pressure ratio
c. Higher temperatures on the back end of the turbine section
d. Less air flow throughput
e. Higher costs for little gain
d. Less air flow throughput
- The preparation for startup of a gas turbine usually assumes:
a. Subsystem checkout first
b. Turning on the cooling water
c. Starting some auxiliary systems
d. Automatic operation at remote sites
e. It is done by operator interaction
d. Automatic operation at remote sites
- When the gas turbine start button is pressed what will start first:
a. Lubrication pump start
b. Hydraulic pump start
c. Ventilation fans start
d. Gas valves close
e. Permissives are checked
c. Ventilation fans start
- Purging starts when:
a. The compressor runs up
b. Air flow is established
c. Compressor reaches maximum
d. Air flow reaches peak
e. Starter motor disengages
b. Air flow is established
- Startup after a trip is done by:
a. Satisfying all the ‘permissives’
b. The operator initiating a restart
c. The computers re-initiating the startup
d. Resetting of the system
e. Selecting the manual restart on the screen
d. Resetting of the system
- The Recycle valve is used to:
a. Load the compressor
b. Recycle hot compressor air for inlet warming
c. Allow the turbine to rapidly increase loading
d. Control the combustion in the combustion chambers
e. Recycle cooling air back to the combustion chamber
a. Load the compressor
- Loading is started when:
a. The generator is at minimum
b. After the warm up
c. The recycle valve is fully open
d. Pressures stabilize
e. The bleed valves are fully open
b. After the warm up
- A rapid decrease in gas turbine speeds can result in:
a. Overcooling the unit
b. High pressures in the compressor sections
c. High pressures in the turbine sections
d. Failure of the recycle valve
e. Combustion being interrupted
e. Combustion being interrupted
- Prior to lighting off the turbine the operator must:
a. Allow the speed to drop to idle
b. Allow the bleed valves to fully open
c. Check the guide vane position
d. Warm the turbine slowly
e. Open the fuel valves
d. Warm the turbine slowly
- The first step in a normal gas turbine shutdown is:
a. Close the fuel valve
b. Cool down the turbine
c. Reduce speed to idle
d. Open the recycle valve
e. Take load of the generator
c. Reduce speed to idle
- Fast shutdowns should be avoided because___________.
a. of the rapid cool down
b. of increased wear on the unit
c. most gas valves can not react quick enough
d. will cause other units to trip
e. can cause flexing of the compressor blades
b. of increased wear on the unit
- Turbine rotor speed on shutdown decreases once___________.
a. the cool down timer times out
b. the shaft speed decreases below preset limit
c. the turning gear takes over
d. the fuel valve closes
e. the main oil pump shuts down
d. the fuel valve closes
- Once the turbine rotor stops on some models_____________.
a. the barring gear starts
b. the cool down timer times out
c. the auxiliary oil pump starts
d. the main oil pump shuts down
e. the jacking oil pump starts
a. the barring gear starts
- The fuel valve closing first on a shutdown is a sign of_________________.
a. an operator error
b. an emergency shutdown
c. a failure of the postlube pump
d. a failure of the cool down timer
e. a failure of the recycle valve
b. an emergency shutdown
- The purpose of a gas turbine water wash is to__________________.
a. clean the unit front to back
b. clean the combustion blades
c. clean the gas headers injectors and burners
d. clean the combustion chambers
e. clean the compressor blading
e. clean the compressor blading
- The cleaning of a gas turbine is accomplished by_____________.
a. taking the unit offline and washing each section individually
b. injecting cleaners into the gas or fuel system to clean the internals
c. shutting down the rotor
d. running a liquid or abrasive through the blades
e. injecting cleaners while the unit is running under load
d. running a liquid or abrasive through the blades
- A carbo-blast cleaning consists of__________________.
a. using carbon black to clean the unit
b. removing all the carbon by blasting it off with solvents
c. removing all the dirt by scrubbing the blades with rice
d. removing dirt and carbon with high pressure water
e. removing carbon from the gas passages, blades, and nozzles
c. removing all the dirt by scrubbing the blades with rice
- Water wash is accomplished by_____________________.
a. using hard water to scrub the blades
b. using scrub water mixed with sodium, potassium and vanadium
c. injecting water and cleaning solvents into the compressor
d. by adding cleaning solvents to the turbine at one half load
e. by scrubbing all parts with brushes and solvents
c. injecting water and cleaning solvents into the compressor
- Off-line washing is performed by____________________.
a. having the unit isolated and the speed at zero
b. injecting cleaners into the inlet at 50% rated speed
c. injecting cleaners at 30% rated speed
d. injecting cleaners into the inlet at zero shaft speed
e. injecting cleaners at crank speed
e. injecting cleaners at crank speed
- Water or steam injection reduces NOX emissions from a gas turbine by:
a. Creating a reaction environment to bind the NOX compounds
b. Preventing corrosion
c. Dropping the combustion temperature
d. Facilitating the production of H2 NO3
e. Allowing the removal of excess steam from the combustion process chamber
c. Dropping the combustion temperature
