3B2 E2.5 C5 Review
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Questions and Answers

What type of bearings are common in aero-derivative gas turbines?

  • Radial bearings
  • Journal bearings
  • Tilt-pad bearings
  • Antifriction (roller and/or ball) bearings (correct)

    • Which type of bearing is most common in heavy-duty, industrial gas turbines?

  • Antifriction (ball) bearings
  • Radial (journal) bearings
  • Squeeze film bearings
  • Tilt-pad bearings (correct)

    • What is the purpose of the special upper squeeze film in the antifriction bearing shown in Figure 1?

  • To increase the bearing's load-carrying capacity
  • To decrease the bearing lifespan
  • To reduce the number of bearings needed
  • To dampen the bearing and increase its life (correct)

    • Which type of bearing would typically be found in a heavy-duty gas turbine with heavier rotors?

    <p>Tilt-pad bearings</p> Signup and view all the answers

    Where are thrust bearings typically located in a typical dual-shaft heavy-duty gas turbine?

    <p>At the inlet end of the compressor and next to the power turbine bearings</p> Signup and view all the answers

    What is the function of the lube oil system in gas turbines?

    <p>To lubricate the bearings that support the rotor</p> Signup and view all the answers

    What is the main function of the pre/post lube oil pump in a gas turbine hydraulic system?

    <p>To cool and lubricate the bearings after shutdown</p> Signup and view all the answers

    What is the purpose of the differential pressure alarm in a gas turbine hydraulic system?

    <p>To protect against high oil temperature and low oil pressure</p> Signup and view all the answers

    What is the role of the hydraulic system in a gas turbine hydraulic system?

    <p>To supply high-pressure oil for the actuation of the main turbine instrumentation</p> Signup and view all the answers

    What is the role of the chip detectors in a gas turbine hydraulic system?

    <p>To detect metal particles in the oil</p> Signup and view all the answers

    What is the function of the oil coolers in a gas turbine hydraulic system?

    <p>To cool the oil before it enters the bearings</p> Signup and view all the answers

    What is typically monitored and displayed on computer screens in a gas turbine hydraulic system?

    <p>System temperatures and pressures, and the status of pumps, filters, and coolers</p> Signup and view all the answers

    What type of bearings do heavy-duty gas turbines normally use?

    <p>Radial bearings</p> Signup and view all the answers

    What is a characteristic of aero-derivative gas turbines' lube oil systems?

    <p>They require a small lube oil system</p> Signup and view all the answers

    What is the purpose of the scavenge system in a lube oil system?

    <p>To return oil from the bearings to the supply and treating equipment</p> Signup and view all the answers

    What is the purpose of the duplex, full-flow filter in the lube oil system?

    <p>To filter the oil while running</p> Signup and view all the answers

    What is the purpose of the chip detector in the bearings' sumps?

    <p>To detect metal particles from damaged bearings</p> Signup and view all the answers

    What type of oil is typically used in heavy-duty gas turbines' lube oil systems?

    <p>Mineral oil</p> Signup and view all the answers

    What is the main difference between aero-derivative and heavy-duty gas turbines' lube oil systems?

    <p>The type of bearings used</p> Signup and view all the answers

    What is the purpose of the thermostatically controlled heater in the lube oil system?

    <p>To ensure a minimum temperature is maintained when the unit is not operating</p> Signup and view all the answers

    What is the function of the oil reservoir in a lube oil system?

    <p>To ensure an adequate supply of oil</p> Signup and view all the answers

    What is the purpose of the motor-driven pre/post lube oil pump in a gas turbine system?

    <p>To supply oil solely during startup and shutdown</p> Signup and view all the answers

    In a heavy-duty gas turbine, when does the motor-driven pre/post lube oil pump run?

    <p>Both before startup and after shutdown</p> Signup and view all the answers

    What is the function of the third pump in a heavy-duty gas turbine lube oil system?

    <p>Backup in case of power loss</p> Signup and view all the answers

    What is the purpose of the duplex filters in a gas turbine lube oil system?

    <p>Allow filter replacement during operation</p> Signup and view all the answers

    Why is the oil in a heavy-duty gas turbine lube oil system cooled before entering the bearings?

    <p>To prevent bearing damage</p> Signup and view all the answers

    What is the purpose of the hydraulic pump provided downstream of the main lube oil pump in a gas turbine system?

    <p>Control speed and load of the turbine</p> Signup and view all the answers

    Which type of bearing is commonly used to dampen vibrations in aero-derivative gas turbines?

    <p>Antifriction (roller) bearing</p> Signup and view all the answers

    In a heavy-duty gas turbine, how many tilting pads are usually present in a radial tilt-pad bearing?

    <p>Five</p> Signup and view all the answers

    What type of bearing is exclusively used in dual-shaft heavy-duty gas turbines for the power turbine?

    <p>Radial (tilt-pad) bearings</p> Signup and view all the answers

    What is the primary function of the lube oil system in aero-derivative gas turbines compared to heavy-duty industrial gas turbines?

    <p>Same primary function and similar components</p> Signup and view all the answers

    What material is typically used to construct the tilting pads in a radial tilt-pad bearing?

    <p>Alloy steel</p> Signup and view all the answers

    What type of bearings and special features are typically used to dampen engine vibrations in aero-derivative gas turbines?

    <p>Antifriction bearings with a special upper squeeze film</p> Signup and view all the answers

    What is a significant advantage of the synthetic oil used in aero-derivative gas turbines over the mineral oil used in heavy-duty gas turbines?

    <p>Synthetic oil has a higher temperature capability</p> Signup and view all the answers

    What is the purpose of the duplex, water-cooled coolers in the aero-derivative lube oil system?

    <p>To maintain oil temperatures within operating limits</p> Signup and view all the answers

    What is the role of the thermostatically controlled heater in the aero-derivative lube oil system?

    <p>To maintain lubrication properties during shutdown</p> Signup and view all the answers

    What is an effect of using radial bearings in heavy-duty gas turbines compared to aero-derivative gas turbines?

    <p>They generate higher temperatures requiring more cooling</p> Signup and view all the answers

    How do chip detectors help diagnose damage in gas turbine bearings?

    <p>By using a magnet to attract metallic particles</p> Signup and view all the answers

    What is the main advantage of using synthetic oil in the aero-derivative lube oil system?

    <p>It can withstand high temperatures</p> Signup and view all the answers

    Which type of bearings is most commonly used in aero-derivative gas turbines?

    <p>Antifriction bearings</p> Signup and view all the answers

    What function does the auxiliary gearbox serve in an aero-derivative gas turbine lube oil system?

    <p>It drives the positive displacement pump</p> Signup and view all the answers

    What type of oil reservoir is typically used in the aero-derivative lube oil system?

    <p>304 Stainless Steel tank</p> Signup and view all the answers

    What is the role of the high oil temperature, low oil pressure, and high filter differential pressure switches in a lube oil system?

    <p>They protect the oil supplied equipment</p> Signup and view all the answers

    What is the primary function of the fuel metering valve in a gas turbine?

    <p>Control the rate of fuel flow accurately</p> Signup and view all the answers

    Why are additional shutoff valves provided for emergency purposes in a fuel system?

    <p>To safeguard against temperature increases that might damage the turbine</p> Signup and view all the answers

    What is the role of the 65BA valve in a fuel system?

    <p>Main shutoff valve</p> Signup and view all the answers

    In a fuel gas system, which component is starting to become more common, indicating a shift in technology?

    <p>Electrically actuated valves</p> Signup and view all the answers

    Why is routine maintenance essential in fuel gas systems?

    <p>To check for fuel gas leaks</p> Signup and view all the answers

    What is the purpose of changing fuel filters at the required differential pressure in a fuel system?

    <p>To ensure the right fuel quantity is provided for operating conditions</p> Signup and view all the answers

    What is the primary reason for heating natural gas in a gas turbine system?

    <p>To remove liquids and ensure a stable energy value</p> Signup and view all the answers

    Which component is responsible for protecting against over or under pressure conditions in a fuel gas system?

    <p>Low and high pressure switches</p> Signup and view all the answers

    What is the purpose of the fuel gas flow meter in a fuel gas system?

    <p>To enable the determination of fuel consumption</p> Signup and view all the answers

    Why is natural gas considered the best fuel for gas turbines?

    <p>Because it promotes the most efficient combustion and produces the lowest environmental emissions</p> Signup and view all the answers

    What is the purpose of the heat exchanger in some fuel gas systems?

    <p>To remove liquids and increase fuel temperature</p> Signup and view all the answers

    What characteristic is required of natural gas to be used in gas turbines?

    <p>Heating values within a specified range and free of liquid contaminants</p> Signup and view all the answers

    What component in the fuel system is responsible for ensuring the right amount of fuel is provided for the operating conditions?

    <p>The 65BA valve</p> Signup and view all the answers

    What component in the fuel system is primarily responsible for preventing temperature increases that might damage the turbine?

    <p>The 65BA valve</p> Signup and view all the answers

    What component in the fuel system is a pressure regulator?

    <p>The 310 valve</p> Signup and view all the answers

    What component in the fuel system is the main shutoff valve?

    <p>The 20F12 valve</p> Signup and view all the answers

    What maintenance task is performed to ensure that the fuel filters are still functioning optimally?

    <p>Changing fuel filters at the required differential pressure</p> Signup and view all the answers

    What is a typical display used for monitoring a fuel system called?

    <p>Computer Control System Display</p> Signup and view all the answers

    What is the primary reason for specifying a certain range of heating values for natural gas in a gas turbine?

    <p>To ensure efficient combustion and lowest environmental emissions</p> Signup and view all the answers

    What is the function of the pressure regulator in a fuel gas system?

    <p>To ensure steady fuel pressures at the combustor</p> Signup and view all the answers

    What is the consequence of using fuel with a low energy value in a gas turbine?

    <p>Special fuel nozzles and combustors have to be installed with adapted fuel gas system</p> Signup and view all the answers

    What is the purpose of the fuel filter in a fuel gas system?

    <p>To prevent contaminants from entering the fuel system</p> Signup and view all the answers

    What is the primary function of the heat exchanger in some fuel gas systems?

    <p>To remove liquids and increase fuel temperature to required levels</p> Signup and view all the answers

    What is the purpose of the low and high pressure switches in a fuel gas system?

    <p>To protect against over or under pressure conditions</p> Signup and view all the answers

    What type of treatment is required for blended heavy distillates as a fuel in a gas turbine?

    <p>Some treatment is required</p> Signup and view all the answers

    What elements, if present in fuel oil, cause rapid corrosion in the turbine section?

    <p>Sodium, Potassium, and Vanadium</p> Signup and view all the answers

    What purpose does the main metering valve serve in a typical liquid fuel system?

    <p>It is used for controlling the flow rate of the fuel</p> Signup and view all the answers

    Which component in the fuel system is a pressure regulator?

    <p>Pressure regulator is not mentioned in the given information</p> Signup and view all the answers

    What gas turbine installations feature dual fuel capability?

    <p>Some gas turbine installations</p> Signup and view all the answers

    What is the main difference between aero-derivative and heavy-duty gas turbines' lube oil systems?

    <p>Heavy-duty gas turbines have an auxiliary gearbox, while aero-derivative gas turbines do not</p> Signup and view all the answers

    In a dual fuel system, which fuel is typically sent to the burners based on the electronic control unit's selection?

    <p>Either liquid fuel or fuel gas</p> Signup and view all the answers

    Which of the following maintenance tasks is NOT typically performed daily in fuel oil systems?

    <p>Calibrating instrumentation and testing protective devices</p> Signup and view all the answers

    What is the purpose of a special fuel nozzle in a dual fuel system?

    <p>To handle both liquid fuel and fuel gas</p> Signup and view all the answers

    Which of the following is a characteristic of fuel oil systems?

    <p>Relatively maintenance free</p> Signup and view all the answers

    What happens when specialized fuel treatment is required in fuel oil systems?

    <p>More maintenance is generally required</p> Signup and view all the answers

    What can be burned simultaneously in some dual fuel systems?

    <p>A mixture of gaseous and liquid fuels</p> Signup and view all the answers

    What is the impact of the quality of fuel on the life of a gas turbine?

    <p>It decreases the life of the gas turbine</p> Signup and view all the answers

    In a typical liquid fuel system, which chemicals are especially harmful to the turbine section?

    <p>Sodium, potassium, and vanadium</p> Signup and view all the answers

    What is the primary function of the main metering valve in a liquid fuel system?

    <p>Direct fuel to the turbine</p> Signup and view all the answers

    What is the initial step in a typical liquid fuel system after fuel storage?

    <p>Fuel treatment</p> Signup and view all the answers

    For which type of liquid fuel does treatment vary based on the fuel?

    <p>Blended heavy distillates</p> Signup and view all the answers

    Which of the following components is crucial in protecting against turbine damage in a liquid fuel system?

    <p>Fuel filters</p> Signup and view all the answers

    What is one of the functions of the electronic control unit in a dual fuel system?

    <p>Controlling the switchover between liquid and gas fuel</p> Signup and view all the answers

    In a dual fuel system, which component requires special attention during maintenance due to the need to manage two types of fuels?

    <p>The control system</p> Signup and view all the answers

    Why would more maintenance generally be needed in a dual fuel system if specialized fuel treatment is required?

    <p>Because of the added complexity of the control system</p> Signup and view all the answers

    What is a consequence of burning a mixture of gaseous and liquid fuels simultaneously in some dual fuel systems?

    <p>Enhanced combustion control challenges</p> Signup and view all the answers

    What is the purpose of changing fuel filters at the required differential pressure in a dual fuel system?

    <p>To prevent clogging and maintain system efficiency</p> Signup and view all the answers

    Which daily maintenance task is typically performed to ensure the proper functioning of a dual fuel system?

    <p>Checking for fuel oil leaks</p> Signup and view all the answers

    What is the practical limit for NOX emissions achievable with water or steam injection for liquid fuels?

    <p>42 ppm</p> Signup and view all the answers

    What technology is mostly replacing the standard scrubbing method for limiting NOX emissions?

    <p>Dry low NOX (DLN) technology</p> Signup and view all the answers

    How do dry low NOX combustion systems achieve lower emissions levels?

    <p>By increased combustion area and premixing air and fuel</p> Signup and view all the answers

    What kind of configuration does a DLE combustion system use in comparison to single fuel nozzles?

    <p>Triple annulus arrangement</p> Signup and view all the answers

    When do the different fuel nozzles get activated in a dry low NOX combustion system?

    <p>Staged over the operation of the gas turbine</p> Signup and view all the answers

    What future technology is mentioned in the text that can offer very low levels of emissions but is still in the research and development stages?

    <p>Catalytic systems</p> Signup and view all the answers

    What is the main purpose of using water or steam injection in gas turbines?

    <p>To reduce the formation of NOX</p> Signup and view all the answers

    What are the potential disadvantages of using water or steam injection in gas turbines?

    <p>Reduced thermal efficiency and increased corrosion</p> Signup and view all the answers

    What causes the rate of NOX formation to decrease as the temperature decreases?

    <p>The decrease in combustion temperature</p> Signup and view all the answers

    How does the cleanliness and purity of the water or steam used in injection systems affect gas turbines?

    <p>It prevents corrosion of hot section components</p> Signup and view all the answers

    What is the main challenge in achieving the optimal balance between reducing NOX and minimizing CO formation in gas turbines?

    <p>Decreasing the combustion temperature</p> Signup and view all the answers

    What is the primary source of NOX emissions in gas turbines?

    <p>The reaction of nitrogen and oxygen in the air</p> Signup and view all the answers

    What is the primary advantage of dry low NOX combustion systems over water or steam injection?

    <p>Ability to reach lower NOX levels</p> Signup and view all the answers

    What is the typical configuration of fuel nozzles in a dry low NOX combustion system?

    <p>Triple annulus arrangement</p> Signup and view all the answers

    What is the current maximum level of NOX emissions in many locations?

    <p>25 ppm</p> Signup and view all the answers

    What is the principle behind dry low NOX combustion systems?

    <p>Lean premixed combustion</p> Signup and view all the answers

    What is a potential future possibility for achieving very low levels of emissions?

    <p>Catalytic systems</p> Signup and view all the answers

    What is required to achieve low NOX emissions over the entire operating envelope in dry low NOX combustion systems?

    <p>Complicated fuel control</p> Signup and view all the answers

    What is the main disadvantage of water or steam injection in reducing NOX emissions?

    <p>It reduces the thermal efficiency due to energy transferred to water or steam</p> Signup and view all the answers

    What determines the type of injection used in water or steam injection systems?

    <p>The availability of water or steam</p> Signup and view all the answers

    What is the consequence of decreasing the fuel to air ratio in combustion?

    <p>A decrease in NOX formation</p> Signup and view all the answers

    What is the primary purpose of water or steam injection in gas turbines?

    <p>To reduce NOX emissions</p> Signup and view all the answers

    Why is cleanliness and purity of water or steam important in water or steam injection systems?

    <p>To reduce corrosion of hot section components</p> Signup and view all the answers

    What happens to the formation of NOX when combustion temperature decreases?

    <p>It decreases exponentially</p> Signup and view all the answers

    What component is responsible for transmitting power to the front end of the gas turbine rotor?

    <p>Overrunning clutch</p> Signup and view all the answers

    What type of motor is typically used in electric starters for gas turbines?

    <p>AC motor</p> Signup and view all the answers

    Why is a turning gear provided in larger gas turbines?

    <p>To prevent high vibration from a bowed rotor</p> Signup and view all the answers

    What enables the motor speed to be controlled in an electric starter?

    <p>Variable frequency drive</p> Signup and view all the answers

    What is the purpose of a hydraulic ratchet or a slow turning electric motor in gas turbines?

    <p>Slowly turn the shaft after shutdown</p> Signup and view all the answers

    How do electric starters for gas turbines typically differ from pneumatic starters?

    <p>Presence of a variable frequency drive</p> Signup and view all the answers

    Which of the following is not a common device used to provide the initial rotation of the main compressor in a gas turbine?

    <p>Hydraulic starters</p> Signup and view all the answers

    What is the most common type of starting system used in gas turbines?

    <p>Electric motors</p> Signup and view all the answers

    Which of the following is not a feature of the pneumatic starter system?

    <p>It uses the power turbine shaft for starting</p> Signup and view all the answers

    Which of the following is not a benefit of using a pneumatic starter system?

    <p>It requires less maintenance than electric motor starting systems</p> Signup and view all the answers

    Which of the following is not a function of the starting system in a gas turbine?

    <p>Supplying combustion air to the combustor</p> Signup and view all the answers

    What happens to the exhaust of the starter motor in a pneumatic starting system?

    <p>It is vented to the atmosphere</p> Signup and view all the answers

    What role does the starting system play in gas turbines?

    <p>Supplying power for the ignition process</p> Signup and view all the answers

    What is the purpose of the pneumatic starters mentioned in the text?

    <p>Driving the main compressor towards ignition conditions</p> Signup and view all the answers

    Which device is commonly used to provide the initial rotation of the main compressor in gas turbines?

    <p>Small diesel engine</p> Signup and view all the answers

    In gas turbines, why is the starting system disengaged from the compressor shaft after ignition?

    <p>To prevent wear on the starting system components</p> Signup and view all the answers

    Which feature distinguishes pneumatic starters from electric motors in gas turbines?

    <p>They use compressed air for initial rotation</p> Signup and view all the answers

    What is the significance of using high-pressure air or gas in pneumatic starters for gas turbines?

    <p>To drive the main compressor towards combustion conditions</p> Signup and view all the answers

    What is the primary difference between an electric starter and a pneumatic starter system in a gas turbine?

    <p>Electric starters use a variable frequency drive, while pneumatic starters use an overrunning clutch.</p> Signup and view all the answers

    What is the purpose of the turning motor gear in larger gas turbines?

    <p>To slowly turn the shaft for a number of hours after shutdown</p> Signup and view all the answers

    How does the electric starter system maintain motor efficiency?

    <p>By using a variable frequency drive</p> Signup and view all the answers

    Which component is not typically found in a pneumatic starter system?

    <p>Variable frequency drive</p> Signup and view all the answers

    What is the primary function of the turning motor gear in larger gas turbines?

    <p>To engage or disengage the motor and the turbine shaft</p> Signup and view all the answers

    What is the main challenge in achieving optimal balance between reducing NOX and minimizing CO formation in gas turbines?

    <p>Controlling fuel to air ratio</p> Signup and view all the answers

    What is the primary function of the air intake system in a gas turbine?

    <p>To provide clean air for the gas turbine</p> Signup and view all the answers

    In what type of locations might a gas turbine encounter special challenges in terms of the air intake system?

    <p>Deserts or dusty locations</p> Signup and view all the answers

    What is the purpose of the stainless steel screen in the first stage of filtration in the air intake system?

    <p>To prevent entry of major debris</p> Signup and view all the answers

    How are the contaminants separated in the current approach of air intake filtration?

    <p>By a series of small cylindrical filters</p> Signup and view all the answers

    Why is the air intake positioned above the enclosure in a typical intake system design?

    <p>To place the intake in a higher position for cleaner air</p> Signup and view all the answers

    What is the main purpose of using intake cooling and anti-icing in the air intake system?

    <p>To address specific environmental challenges</p> Signup and view all the answers

    What is the purpose of pulse cleaning systems in gas turbines?

    <p>To dislodge dust collected on filters</p> Signup and view all the answers

    Which method is commonly used in gas turbine intake cooling systems to decrease the temperature of the inlet air?

    <p>Spraying water into the intake in fine droplets</p> Signup and view all the answers

    What is the purpose of an anti-icing system in gas turbines?

    <p>To prevent ice formation in the compressor and protect against damage</p> Signup and view all the answers

    Why does introducing warm air into the gas turbine intake affect the unit's capacity?

    <p>It decreases air density</p> Signup and view all the answers

    What does the exhaust system in gas turbines primarily aim to achieve?

    <p>Direct the hot turbine exhaust to a safe location</p> Signup and view all the answers

    Which of the following is a potential risk if ice forms in the gas turbine intake or on the compressor blades?

    <p>Possible catastrophic destruction of the compressor blading</p> Signup and view all the answers

    Why are noise attenuation and silencers important in the exhaust system of gas turbines?

    <p>To meet local requirements and reduce noise levels</p> Signup and view all the answers

    What is the purpose of diverter dampers in the exhaust system of gas turbines?

    <p>To prevent recirculation of exhaust into the air intake</p> Signup and view all the answers

    Why is the increase in air temperature due to anti-icing systems considered a disadvantage?

    <p>It can lead to reduced power output</p> Signup and view all the answers

    Which technique is commonly employed in inlet cooling systems to decrease the temperature of the inlet air?

    <p>Spraying a fine fog in the air intake</p> Signup and view all the answers

    What is the primary advantage of the current approach of using many small cylindrical filters for air intake filtration over the past inertial filtering method?

    <p>Lower maintenance requirements due to fewer moving parts</p> Signup and view all the answers

    Why is an offshore platform installation considered a special challenge for a gas turbine air intake system, compared to a land-based installation?

    <p>The air intake system must withstand higher wind speeds and saltwater corrosion</p> Signup and view all the answers

    How does the positioning of the air intake above the enclosure, as shown in Figure 17, contribute to the cleanliness and efficiency of the air intake system?

    <p>By placing the intake in a higher position, the air is cleaner due to reduced ground-level pollutants</p> Signup and view all the answers

    When compared to heavy-duty gas turbine lube oil systems, what synthetic oil advantage allows aero-derivative gas turbines to operate at higher temperatures without decreasing viscosity?

    <p>Synthetic oil has a higher thermal stability than mineral oil</p> Signup and view all the answers

    Which gas turbine installation typically does NOT feature dual fuel capability?

    <p>A gas turbine installed on an offshore platform</p> Signup and view all the answers

    In dry low NOX combustion systems, which fuel nozzles are activated first, and how does this differ from traditional combustion systems?

    <p>The pilot fuel nozzles are activated first, while main fuel nozzles are activated later in the combustion process</p> Signup and view all the answers

    What is the mechanism behind inlet cooling systems that decreases the temperature of the inlet air and increases power output in a gas turbine?

    <p>Evaporative cooling</p> Signup and view all the answers

    When using evaporative pads for inlet cooling in a gas turbine, what is the optimal type of pad to utilize?

    <p>Soft cellulose and synthetic pads</p> Signup and view all the answers

    Why does the introduction of warm air into the gas turbine intake result in a decrease in the capacity of the unit?

    <p>Warm air is less dense than cold air, leading to lower mass flow through the turbine</p> Signup and view all the answers

    What type of burner system is sometimes included prior to a heat recovery system in a gas turbine exhaust?

    <p>Supplemental burner</p> Signup and view all the answers

    Which gases can be emitted during the operation of the Heat Recovery Steam Generator (HRSG) in a combined-cycle gas turbine, that require monitoring?

    <p>NOX and Sulfur Dioxide (SO2)</p> Signup and view all the answers

    Which type of high-efficiency particle collection technology is commonly used as an alternative to electrostatic precipitators for meeting stricter emissions guidelines?

    <p>Fabric filters</p> Signup and view all the answers

    Which gas turbine shaft has a higher rotation frequency compared to the other main shaft?

    <p>High-pressure shaft</p> Signup and view all the answers

    Which type of axial bearing is used between the rotor shaft ends in heavy-duty gas turbines to address high thrust loads?

    <p>Flat roller bearings</p> Signup and view all the answers

    Which type of hydrogen cooler is required to achieve the required water and hydrogen mixture heat rejection in heavy-duty gas turbine cooling systems?

    <p>Direct-liquid cooling</p> Signup and view all the answers

    What type of materials do tilting pads primarily consist of in tilting-pad bearings employed in heavy-duty gas turbines?

    <p>Babbit and cast iron</p> Signup and view all the answers

    During a gas turbine startup, what initiates the rotor rotation?

    <p>Pre-lubrication process</p> Signup and view all the answers

    What occurs during a gas turbine warm-up phase?

    <p>The engine is allowed to idle</p> Signup and view all the answers

    In a gas turbine startup, what happens once the fuel is admitted to the combustion chambers?

    <p>The guide vanes open to their optimum position</p> Signup and view all the answers

    What follows the ventilation fan operation in the gas turbine startup process?

    <p>Pre-lubrication</p> Signup and view all the answers

    What triggers the activation of the back-up pump during a gas turbine startup?

    <p>Attaining adequate fuel pressure</p> Signup and view all the answers

    In a gas turbine startup sequence, what prompts the pre-lube pump to start?

    <p>Achieving adequate pressure</p> Signup and view all the answers

    After the warm-up phase in a gas turbine startup, what is done before increasing the fuel flow?

    <p>Synchronizing speed and phase</p> Signup and view all the answers

    In a gas turbine startup, what triggers the purging of the turbine to ensure no explosive vapors are present?

    <p>Starting the ventilation fans</p> Signup and view all the answers

    What is the purpose of the pre-lubrication process in a gas turbine startup?

    <p>To ensure adequate pressure for fuel admission</p> Signup and view all the answers

    How is the actual operating point of a gas turbine determined during loading after warm-up?

    <p>By slowly closing in on the recycle valve</p> Signup and view all the answers

    What is the assumed state of the electrical, pneumatic, air, instrumentation, and control systems when a start is initiated?

    <p>Activated and energized</p> Signup and view all the answers

    What is the typical method for restarting a gas turbine startup sequence in case of a malfunction or abnormal condition?

    <p>Pressing the reset switch on the panel</p> Signup and view all the answers

    What is displayed on a control panel during the startup process of a gas turbine?

    <p>The startup sequence progress and other operational data</p> Signup and view all the answers

    What is the primary purpose of 'permissives' in a gas turbine startup sequence?

    <p>To allow the start sequence only when certain conditions are met</p> Signup and view all the answers

    In remote applications, how does startup of a gas turbine typically occur?

    <p>Automatically without human participation</p> Signup and view all the answers

    What happens if certain conditions occur or specific requirements are not met at some point in the startup sequence?

    <p>The startup will be aborted and the unit stopped</p> Signup and view all the answers

    What is the primary condition that must be satisfied before the startup sequence of a gas turbine can proceed?

    <p>All permissives are satisfied</p> Signup and view all the answers

    What is the role of the control system during the startup of a gas turbine?

    <p>To manage the startup sequence and ensure it occurs in the correct order</p> Signup and view all the answers

    What is the purpose of the reset switch on the control panel?

    <p>To reset the system after a malfunction or abnormal condition</p> Signup and view all the answers

    What is the typical mode of operation for startup in remote applications?

    <p>Automatic startup</p> Signup and view all the answers

    What happens if certain conditions are not met during the startup sequence of a gas turbine?

    <p>The startup sequence is aborted</p> Signup and view all the answers

    What is the purpose of the control panel used to monitor startup, shutdown, and operation of a gas turbine?

    <p>To display the progress of the startup sequence</p> Signup and view all the answers

    What is the primary function of the guide vanes during a gas turbine's startup sequence?

    <p>To control the rotational speed of the turbine</p> Signup and view all the answers

    What is the role of the reset switch on the control panel during a gas turbine startup sequence?

    <p>To restart the startup sequence if it was aborted</p> Signup and view all the answers

    What is the purpose of the differential pressure alarm in a gas turbine hydraulic system?

    <p>To detect any leaks in the hydraulic system</p> Signup and view all the answers

    What is the effect of a sudden increase in speed during the operation of a gas turbine?

    <p>A rapid increase in turbine temperature</p> Signup and view all the answers

    What is the primary purpose of the main metering valve in a liquid fuel system?

    <p>To control the flow rate of the fuel</p> Signup and view all the answers

    What is the role of the duplex filters in a gas turbine lube oil system?

    <p>To remove contaminants from the lube oil</p> Signup and view all the answers

    What type of oil is typically used in heavy-duty gas turbines' lube oil systems?

    <p>Synthetic-based oil</p> Signup and view all the answers

    What is the purpose of using high-pressure air or gas in pneumatic starters for gas turbines?

    <p>To increase the torque delivered to the turbine</p> Signup and view all the answers

    What triggers the activation of the backup pump during a gas turbine startup?

    <p>A drop in lube oil pressure below a certain threshold</p> Signup and view all the answers

    What is the primary advantage of dry low NOX combustion systems over water or steam injection in reducing NOX emissions?

    <p>Reduced system complexity</p> Signup and view all the answers

    What is the first step in a normal shutdown procedure of a gas turbine?

    <p>Reducing speed to idle</p> Signup and view all the answers

    What initiates the rotor rotation during a gas turbine startup?

    <p>The startup of the turning gear</p> Signup and view all the answers

    In certain situations, what triggers a fast shutdown in a gas turbine?

    <p>When a protective device detects an abnormal condition</p> Signup and view all the answers

    What is the main challenge in achieving the optimal balance between reducing NOX and minimizing CO formation in gas turbines?

    <p>The complex interaction of the combustion process</p> Signup and view all the answers

    What component in the fuel system is primarily responsible for minimizing temperature increases that might damage the turbine?

    <p>The pressure regulator</p> Signup and view all the answers

    What is the role of the differential pressure alarm in a gas turbine hydraulic system?

    <p>It alerts for low oil pressure to prevent damage to the hydraulic system</p> Signup and view all the answers

    What is the primary purpose of the cooldown period during a normal shutdown of a gas turbine?

    <p>To minimize the negative thermal effects on the engine</p> Signup and view all the answers

    Which event triggers the postlube pump to start up during a normal shutdown?

    <p>Main lube oil pump pressure loss</p> Signup and view all the answers

    What happens when an abnormal condition, such as high vibration, is detected during the operation of a gas turbine?

    <p>The gas turbine undergoes a fast shutdown</p> Signup and view all the answers

    What occurs when the fuel valve is closed in a normal shutdown sequence?

    <p>Combustion is extinguished and the rotor speed decreases until it stops</p> Signup and view all the answers

    Which system component is responsible for lubricating and cooling the bearings for a specified time period after the rotor stops during a normal shutdown?

    <p>Postlube pump</p> Signup and view all the answers

    What happens when an operator initiates an emergency stop on a gas turbine?

    <p>A fast shutdown is initiated</p> Signup and view all the answers

    What is the primary purpose of reducing speed to idle in a normal shutdown of a gas turbine?

    <p>To minimize the negative thermal effects</p> Signup and view all the answers

    What happens to the main lube oil pump during a normal shutdown of a gas turbine?

    <p>It loses pressure as the rotor speed decreases</p> Signup and view all the answers

    What is the primary difference between a normal shutdown and a fast shutdown of a gas turbine?

    <p>The cooldown period is eliminated in a fast shutdown</p> Signup and view all the answers

    What is the purpose of the postlube pump in a gas turbine shutdown?

    <p>To lubricate and cool the bearings for a specified time period</p> Signup and view all the answers

    In what situation would a fast shutdown of a gas turbine be initiated?

    <p>When an abnormal condition is detected</p> Signup and view all the answers

    What happens to the rotor speed during a normal shutdown of a gas turbine?

    <p>It decreases until the rotor stops</p> Signup and view all the answers

    What is a key consideration for the water used in the waterwash process for gas turbines?

    <p>Chemical contamination</p> Signup and view all the answers

    What is the recommended action if the temperature is less than 4°C during the waterwash process?

    <p>Add ethylene glycol to prevent icing</p> Signup and view all the answers

    Which scenario would prompt manual scrubbing of the gas turbine's intake during a waterwash?

    <p>Stubborn deposits on the blades</p> Signup and view all the answers

    What is a critical requirement for the cleaning agents used during the waterwash process?

    <p>Acceptance by gas turbine vendors</p> Signup and view all the answers

    During the off-line waterwash, what procedure is carried out before reconnecting various lines?

    <p>Spraying the turbine with water</p> Signup and view all the answers

    What is the purpose of injecting the waterwash fluid during an on-line wash of a gas turbine?

    <p>To perform cleaning while the engine is running</p> Signup and view all the answers

    What is the primary cause of deterioration in gas turbine performance?

    <p>Compressor fouling</p> Signup and view all the answers

    What are the disadvantages of using abrasive materials for compressor cleaning?

    <p>Plugging up cooling passages and turbine blade cooling holes</p> Signup and view all the answers

    What is the most effective method of compressor cleaning?

    <p>Off-line waterwash</p> Signup and view all the answers

    What is the source of contamination leading to compressor fouling?

    <p>Airborne particles</p> Signup and view all the answers

    What can make the compressor fouling problem worse?

    <p>Compressor bearing oil leak</p> Signup and view all the answers

    What problems can compressor fouling lead to?

    <p>Compressor surging and acceleration problems</p> Signup and view all the answers

    What is a key consideration when using water for the waterwash process in gas turbines?

    <p>The cleanliness and conformity to quality standards</p> Signup and view all the answers

    During off-line waterwash, what should be done before initiating the cleaning process?

    <p>Disconnect bleed and drain lines</p> Signup and view all the answers

    What happens to the engine during on-line waterwash?

    <p>It runs at idle speed</p> Signup and view all the answers

    Why do operators manually scrub the gas turbine intake during waterwash in some cases?

    <p>To remove stubborn deposits</p> Signup and view all the answers

    What is the purpose of injecting a mixture of water and ethylene glycol when the temperature is less than 4°C?

    <p>To avoid ice formation</p> Signup and view all the answers

    Which type of deposits are particularly addressed by using additional cleaning agents and solvents in the waterwash process?

    <p>Oily substances</p> Signup and view all the answers

    What is the primary cause of deterioration in gas turbine performance?

    <p>Fouling of the compressor blading</p> Signup and view all the answers

    What is the most common source of contamination in gas turbine fouling?

    <p>Dust, salt and other airborne particles</p> Signup and view all the answers

    What is the most effective method of compressor cleaning?

    <p>Off-line waterwash</p> Signup and view all the answers

    What is a disadvantage of using abrasive materials for compressor cleaning?

    <p>It plugs up cooling passages in the compressor and cooling holes in the turbine blades</p> Signup and view all the answers

    What is the result of compressor fouling on gas turbine performance?

    <p>Decrease in compressor efficiency</p> Signup and view all the answers

    What can also result from compressor fouling?

    <p>Compressor surging and acceleration problems</p> Signup and view all the answers

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