3RD CLASS POWER ENGINEERING - B2
- PART 2 EXAM QUESTIONS AND
ANSWERS. VERIFIED 2026.
How many times are fuel oils for gas turbines filtered? - ANS Twice
At the fuel metering valve, there is an overflow for unused fuel that returns fuel back to the
tank. True or False? - ANS True
Protective instrumentation for fuel oils includes differential pressure and high pressure. True or
False? - ANS False, DP and LOW pressure
Dual Fuel oil systems? - ANS - A special fuel nozzle is required and the control system is more
complex than a conventional single fuel system
- In some units, a mixture of gaseous and liquid fuels can be burned simultaneously
More maintenance is generally required when specialized fuel treatment is needed. True or
False? - ANS True
Maintenance of liquid fuel systems consists of: - ANS - Checking for leaks daily
- Checking pressures and temperatures daily
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,- Cleaning centrifuges, replenishing chemicals
- Changing fuel filters
- Calibrating instruments and testing protective devices
NOx refers to a family of compounds: - ANS NO and NO2. Naturally occur during the
combustion of nitrogen and oxygen, and are partially responsible for acid rain.
NOx formation increases as temperature decreases. True or False? - ANS False, formation
DECREASES as temperatures DECREASES
Best way to lower NOx formation? - ANS Decrease fuel-air ratio and operate with a lean fuel
mixture
Practical limits for NOx emissions when using steam injection? - ANS - 25 ppm for natural gas
- 42 ppm for liquid fuels
Considerations to make when using steam injection for NOx control? - ANS - Cleanliness or
purity of the water to prevent corrosion
- Water/steam can be injected in the combustion section through the fuel nozzles, or can be
premixed with fuels in a separate manifold
The main disadvantage of water/steam injection is corrosion, along with the reduction in
thermal efficiency because of all the heat energy absorbed by the steam or water. True or False?
- ANS True
Modern scrubbing method for limiting NOx formation? - ANS Using Dry Low NOx combustion
systems (some systems around 9 ppm, with 25 ppm being the maximum standard)
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,Operating principle for Dry Low NOx systems? - ANS - Lean premixed combustion and fired at
lower temperatures
- An increase in combustion area is required and triple annulus fuel nozzles can be used rather
than single fuel nozzles
A power source must be installed on every gas turbine to provide the initial compression for
ignition. True or False? - ANS True. Typically a starting system engages the compressor shaft
during start-up, and disengages it during normal operation.
List of power sources for GT start up? (of the compressor) - ANS - Pneumatic starters using
compressed air or gas
- Electric motors
- Small diesel engines
- Steam turbine expanders
*Pneumatic starters and electric motors are most common*
In some cases, the a HP gas source can actually be used for starting a gas turbine by expanding
gas through the turbine section of a machine. True or False? - ANS True
The exhaust of a starter motor is normally vented to atmosphere. True or False? - ANS True
Electric starter motors for gas turbines are usually of the DC power type. True or False? -
ANS False, they are usually AC powered, VFD drives
Turning gears are installed on gas turbines for what reason? - ANS - To prevent sagging or
bowing
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, - If a rotor becomes bowed, the rotor may lock and prevent startup or may result in high
vibration until the bow slowly disappears
2 most common types of GT turning gears? - ANS Hydraulic ratchet type or an electric motor
The type of air intake system for a gas turbine is dependant on what? - ANS The
environmental conditions encountered at the gas turbine location
Special challenges are posed in what types of climates for gas turbines? - ANS Offshore
platforms, close to the ocean, deserts or dusty locations, or in arctic environments.
Modern day inlet filter technology for GT's? - ANS - Small cylindrical filters are most common
- "Pulse cleaning systems" use compressed air to back flow and clean plugged filters
- Also referred to as "huff and puff" filters and work on pressure differential
Inlet cooling systems are all based off what principle? - ANS - Evaporative cooling
- When water evaporates, it requires a large amount of latent heat, which is provided by the
warmer air
- The result is a drop in air temperature
3 various methods for Inlet Cooling used in modern day? - ANS - Spray cooling where air is
sprayed into the intake in fine droplets
- Fog cooling where a fine fog is produced using a high pressure spray
- Special evaporative pads
The formation of ice in the air intake or on the first few stages of the compressor can occur if a
certain combination of temperature and humidity occurs. True or False? - ANS True.
4 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
- PART 2 EXAM QUESTIONS AND
ANSWERS. VERIFIED 2026.
How many times are fuel oils for gas turbines filtered? - ANS Twice
At the fuel metering valve, there is an overflow for unused fuel that returns fuel back to the
tank. True or False? - ANS True
Protective instrumentation for fuel oils includes differential pressure and high pressure. True or
False? - ANS False, DP and LOW pressure
Dual Fuel oil systems? - ANS - A special fuel nozzle is required and the control system is more
complex than a conventional single fuel system
- In some units, a mixture of gaseous and liquid fuels can be burned simultaneously
More maintenance is generally required when specialized fuel treatment is needed. True or
False? - ANS True
Maintenance of liquid fuel systems consists of: - ANS - Checking for leaks daily
- Checking pressures and temperatures daily
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,- Cleaning centrifuges, replenishing chemicals
- Changing fuel filters
- Calibrating instruments and testing protective devices
NOx refers to a family of compounds: - ANS NO and NO2. Naturally occur during the
combustion of nitrogen and oxygen, and are partially responsible for acid rain.
NOx formation increases as temperature decreases. True or False? - ANS False, formation
DECREASES as temperatures DECREASES
Best way to lower NOx formation? - ANS Decrease fuel-air ratio and operate with a lean fuel
mixture
Practical limits for NOx emissions when using steam injection? - ANS - 25 ppm for natural gas
- 42 ppm for liquid fuels
Considerations to make when using steam injection for NOx control? - ANS - Cleanliness or
purity of the water to prevent corrosion
- Water/steam can be injected in the combustion section through the fuel nozzles, or can be
premixed with fuels in a separate manifold
The main disadvantage of water/steam injection is corrosion, along with the reduction in
thermal efficiency because of all the heat energy absorbed by the steam or water. True or False?
- ANS True
Modern scrubbing method for limiting NOx formation? - ANS Using Dry Low NOx combustion
systems (some systems around 9 ppm, with 25 ppm being the maximum standard)
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,Operating principle for Dry Low NOx systems? - ANS - Lean premixed combustion and fired at
lower temperatures
- An increase in combustion area is required and triple annulus fuel nozzles can be used rather
than single fuel nozzles
A power source must be installed on every gas turbine to provide the initial compression for
ignition. True or False? - ANS True. Typically a starting system engages the compressor shaft
during start-up, and disengages it during normal operation.
List of power sources for GT start up? (of the compressor) - ANS - Pneumatic starters using
compressed air or gas
- Electric motors
- Small diesel engines
- Steam turbine expanders
*Pneumatic starters and electric motors are most common*
In some cases, the a HP gas source can actually be used for starting a gas turbine by expanding
gas through the turbine section of a machine. True or False? - ANS True
The exhaust of a starter motor is normally vented to atmosphere. True or False? - ANS True
Electric starter motors for gas turbines are usually of the DC power type. True or False? -
ANS False, they are usually AC powered, VFD drives
Turning gears are installed on gas turbines for what reason? - ANS - To prevent sagging or
bowing
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, - If a rotor becomes bowed, the rotor may lock and prevent startup or may result in high
vibration until the bow slowly disappears
2 most common types of GT turning gears? - ANS Hydraulic ratchet type or an electric motor
The type of air intake system for a gas turbine is dependant on what? - ANS The
environmental conditions encountered at the gas turbine location
Special challenges are posed in what types of climates for gas turbines? - ANS Offshore
platforms, close to the ocean, deserts or dusty locations, or in arctic environments.
Modern day inlet filter technology for GT's? - ANS - Small cylindrical filters are most common
- "Pulse cleaning systems" use compressed air to back flow and clean plugged filters
- Also referred to as "huff and puff" filters and work on pressure differential
Inlet cooling systems are all based off what principle? - ANS - Evaporative cooling
- When water evaporates, it requires a large amount of latent heat, which is provided by the
warmer air
- The result is a drop in air temperature
3 various methods for Inlet Cooling used in modern day? - ANS - Spray cooling where air is
sprayed into the intake in fine droplets
- Fog cooling where a fine fog is produced using a high pressure spray
- Special evaporative pads
The formation of ice in the air intake or on the first few stages of the compressor can occur if a
certain combination of temperature and humidity occurs. True or False? - ANS True.
4 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
