3B2 E2.5 C4 Review
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Questions and Answers

What is the primary function of the compressor section in a gas turbine?

  • To generate steam for heating purposes
  • To supply high-pressure air for combustion and mass flow (correct)
  • To convert the energy created by hot gases into rotational power
  • To burn fuel and produce hot combustion gases

    • What is the approximate temperature of the air after compression in a gas turbine?

  • 1500°C
  • 650°C (correct)
  • 1000°C
  • 200°C

    • What is the purpose of the dilution air in the combustion chamber?

  • To increase the flame temperature
  • To reduce the pressure in the combustion chamber
  • To provide fuel for combustion
  • To cool the outside of the inner combustion chamber (correct)

    • What happens to the pressure of the gases as they enter the power turbine?

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

    What is the primary purpose of the combustion chamber in a gas turbine?

    <p>To burn fuel and produce hot combustion gases</p> Signup and view all the answers

    What is the purpose of the power turbine in a gas turbine?

    <p>To convert the energy created by hot gases into rotational power</p> Signup and view all the answers

    What is a major drawback of adding intercoolers, regenerators, and/or reheaters to a gas turbine?

    <p>Additional cost and complexity</p> Signup and view all the answers

    What is a characteristic of aero-derivative gas turbines?

    <p>Low weight and easily maintained</p> Signup and view all the answers

    What is an advantage of heavy-duty gas turbines over aero-derivative gas turbines?

    <p>Longer intervals between overhauls</p> Signup and view all the answers

    What is a common use of gas turbines in industrial applications?

    <p>Driving electric power generators</p> Signup and view all the answers

    What is the purpose of a power turbine in an aero-derivative gas turbine?

    <p>To drive a generator</p> Signup and view all the answers

    What is a characteristic of base loading in power generation?

    <p>Producing power on a continuous basis</p> Signup and view all the answers

    What is an advantage of aero-derivative gas turbines in certain applications?

    <p>Fast starting and low weight</p> Signup and view all the answers

    What is a difference between aero-derivative and heavy-duty gas turbines?

    <p>Weight and size</p> Signup and view all the answers

    What is the purpose of external combustors in heavy-duty gas turbines?

    <p>To allow for inter-cooling and regeneration</p> Signup and view all the answers

    What is one advantage of using gas turbines in offshore applications?

    <p>They are lightweight and have a high power-to-weight ratio</p> Signup and view all the answers

    Why are gas turbines not usually suitable for low-power applications?

    <p>Their efficiency decreases at lower loads</p> Signup and view all the answers

    Which of the following is NOT a reason for the high manufacturing costs of gas turbines?

    <p>They have a simple design</p> Signup and view all the answers

    Which type of fuel can be used in gas turbines?

    <p>Liquid and gaseous fuels</p> Signup and view all the answers

    Why is the ability to start rapidly an important advantage for gas turbines in backup power generation?

    <p>It increases their availability and reliability</p> Signup and view all the answers

    What is one disadvantage of gas turbines compared to other types of internal combustion engines?

    <p>They have a slow response to changes in load demand</p> Signup and view all the answers

    In comparison to other internal combustion engines, why is a gas turbine considered less suitable for low-power applications?

    <p>The efficiency of gas turbines decreases at lower loads.</p> Signup and view all the answers

    Why are gas turbines especially suitable for offshore applications?

    <p>They have a high power to weight ratio.</p> Signup and view all the answers

    What is a significant disadvantage of gas turbines compared to other internal combustion engines?

    <p>Gas turbines have high manufacturing costs.</p> Signup and view all the answers

    What characteristic of gas turbines makes them less responsive to changes in load demand compared to other internal combustion engines?

    <p>Slower speed at which they change speed</p> Signup and view all the answers

    Why is the ability to start rapidly essential for gas turbines in backup power generation?

    <p>To minimize outage time by quick replacement</p> Signup and view all the answers

    What is the primary reason for gas turbines being less suitable for low-power applications?

    <p>Decreased efficiency at lower loads</p> Signup and view all the answers

    What is the purpose of the combustion section in a gas turbine?

    <p>To convert the hot combustion gases into mechanical energy</p> Signup and view all the answers

    Why does the temperature of the air increase during compression in a gas turbine?

    <p>As a result of the compression process itself</p> Signup and view all the answers

    What is the function of the dilution air in a gas turbine combustion chamber?

    <p>To aid in the cooling of the inner combustion chamber</p> Signup and view all the answers

    Why are the pressures and temperatures quoted in the text only approximations?

    <p>Due to variability in machine design and size</p> Signup and view all the answers

    What happens to the temperature of the gases as they pass through the power turbine in a gas turbine?

    <p>The temperature decreases significantly</p> Signup and view all the answers

    What drives the external load, such as an electrical generator, in a gas turbine system?

    <p>The mechanical energy developed in the power turbine</p> Signup and view all the answers

    What is the primary reason why gas turbines are not used in low-power applications?

    <p>They are not efficient at low powers</p> Signup and view all the answers

    What is the main advantage of using aero-derivative gas turbines in offshore applications?

    <p>They are lighter in weight</p> Signup and view all the answers

    What is the primary purpose of the combustion gases in a gas turbine?

    <p>To drive the power turbine</p> Signup and view all the answers

    Which of the following is not a characteristic of heavy-duty gas turbines?

    <p>They are lighter in weight</p> Signup and view all the answers

    What is the primary purpose of intercoolers, regenerators, and/or reheaters in a gas turbine?

    <p>To increase the efficiency of the turbine</p> Signup and view all the answers

    What is a common use of gas turbines in industrial applications?

    <p>Driving electric power generators</p> Signup and view all the answers

    What is an advantage of aero-derivative gas turbines over reciprocating engines of the same power rating?

    <p>They are potentially more efficient</p> Signup and view all the answers

    What is the primary purpose of the generator in a gas turbine?

    <p>To generate electricity</p> Signup and view all the answers

    Why are gas turbines used in peak power generation?

    <p>To provide power during periods of high demand</p> Signup and view all the answers

    In a single shaft gas turbine arrangement, which components are mounted on the same shaft?

    <p>Compressor and power turbine</p> Signup and view all the answers

    What is the primary purpose of the high-pressure turbine in a dual shaft gas turbine design?

    <p>Drive the compressor</p> Signup and view all the answers

    Why is a single-shaft gas turbine arrangement mechanically simpler than a two-shaft arrangement?

    <p>No shaft connection between turbines</p> Signup and view all the answers

    What is the role of a reducing gear in a single shaft gas turbine system?

    <p>Align the compressor and power turbine</p> Signup and view all the answers

    What is the difference in the connection of the load between the single shaft layouts shown in Figure 5a and Figure 5b?

    <p>Load always connected at the power turbine end</p> Signup and view all the answers

    What is the primary function of the low-pressure turbine in a dual shaft gas turbine design?

    <p>Drive the generator</p> Signup and view all the answers

    What is the main advantage of the dual-shaft arrangement in a gas turbine system?

    <p>Reducing the size of the starting motor</p> Signup and view all the answers

    Why is the open cycle gas turbine system considered simple?

    <p>The use of atmospheric air as the working fluid throughout the cycle</p> Signup and view all the answers

    What is a major advantage of closed cycle gas turbine systems?

    <p>Higher densities of the working fluid and increased power output</p> Signup and view all the answers

    Why does the closed cycle gas turbine system require cooling water?

    <p>To cool the working fluid after expansion through the power turbine</p> Signup and view all the answers

    What is a significant disadvantage of the open cycle compared to the closed cycle gas turbine systems?

    <p>Low thermal efficiency due to heat loss to the atmosphere</p> Signup and view all the answers

    Which design feature allows closed cycle systems to use higher pressures throughout the cycle?

    <p>Enclosing the working fluid within a closed system</p> Signup and view all the answers

    What is the primary function of the high-pressure turbine in a dual shaft gas turbine design?

    <p>Drive the compressor</p> Signup and view all the answers

    Why is the load usually connected at the power turbine end in a single shaft gas turbine arrangement?

    <p>To simplify the mechanical setup</p> Signup and view all the answers

    What is the primary purpose of having two vertical combustors in a single shaft gas turbine?

    <p>Improve combustion efficiency</p> Signup and view all the answers

    What is a significant drawback of using a two-shaft gas turbine arrangement compared to a single shaft arrangement?

    <p>Complex mechanical setup</p> Signup and view all the answers

    In a single shaft gas turbine system, what is the primary role of the reducing gear?

    <p>Align the compressor and load shafts</p> Signup and view all the answers

    What differentiates the load placement in Figure 5a from Figure 5b in a single shaft gas turbine layout?

    <p>Position relation to the compressor</p> Signup and view all the answers

    What is the primary advantage of the dual-shaft arrangement in a gas turbine system?

    <p>Higher operating flexibility</p> Signup and view all the answers

    What is the primary disadvantage of the open cycle gas turbine system?

    <p>Low thermal efficiency</p> Signup and view all the answers

    In a closed cycle gas turbine system, what is the purpose of the regenerator?

    <p>To exchange heat with the hot exhaust gases</p> Signup and view all the answers

    What is an advantage of using a closed cycle gas turbine system over an open cycle system?

    <p>Higher thermal efficiency</p> Signup and view all the answers

    What is a characteristic of the working fluid in a closed cycle gas turbine system?

    <p>It is clean and does not cause corrosion</p> Signup and view all the answers

    What is a disadvantage of closed cycle gas turbine systems?

    <p>Complexity and increased size of the system</p> Signup and view all the answers

    What component of a gas turbine installation helps in decreasing the air inlet temperature?

    <p>Intake plenum</p> Signup and view all the answers

    In colder climates, where might a gas turbine unit be located?

    <p>In a building with extra maintenance space</p> Signup and view all the answers

    What purpose does the enclosure serve in a gas turbine installation?

    <p>Protect from environment</p> Signup and view all the answers

    Why does some air intake incorporate special cooling systems?

    <p>To decrease the air inlet temperature</p> Signup and view all the answers

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

    <p>To reduce the noise level</p> Signup and view all the answers

    What purpose does the exhaust system serve in a gas turbine installation?

    <p>To provide a safe exit for hot exhaust gases</p> Signup and view all the answers

    What is the purpose of a waste heat recovery heat exchanger in a gas turbine?

    <p>To supply heat to some other process at the overall facility</p> Signup and view all the answers

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

    <p>To provide fuel to the combustion section at the proper temperature, pressure, and flow</p> Signup and view all the answers

    What is the purpose of a reducing gear in a gas turbine?

    <p>To connect the turbine shaft to a driven load</p> Signup and view all the answers

    Why are anti-icing systems necessary in some gas turbines?

    <p>To eliminate the buildup of ice in very cold climates</p> Signup and view all the answers

    What is the purpose of a steam injection system in a gas turbine?

    <p>To reduce emissions and/or increase output</p> Signup and view all the answers

    What is the purpose of a water wash system in a gas turbine?

    <p>To clean compressor blades</p> Signup and view all the answers

    What is the primary function of a reducing gear in a gas turbine system?

    <p>To adjust the speed of the turbine shaft to match the load</p> Signup and view all the answers

    What is the purpose of a steam injection system in a gas turbine?

    <p>To increase mass flow and reduce emissions</p> Signup and view all the answers

    Why are anti-icing systems important in gas turbines?

    <p>To provide heat to eliminate ice buildup in the air intake</p> Signup and view all the answers

    What is the role of a water wash system in a gas turbine?

    <p>To clean compressor blades</p> Signup and view all the answers

    What is the primary function of the lube oil system in a gas turbine?

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

    Why must both the intake and exhaust operate with the lowest possible pressure drop in a gas turbine system?

    <p>To minimize losses in power and efficiency</p> Signup and view all the answers

    What is the primary purpose of the intake plenum in a gas turbine installation?

    <p>To provide smooth flow into the gas turbine compressor section</p> Signup and view all the answers

    What is a common feature of buildings or enclosures that house gas turbines in colder climates?

    <p>Extra lay-down space for maintenance</p> Signup and view all the answers

    What is the primary purpose of the exhaust system in a gas turbine installation?

    <p>To provide a safe exit for the hot exhaust gases</p> Signup and view all the answers

    Why do some air intakes incorporate special cooling systems?

    <p>To increase the air density</p> Signup and view all the answers

    What is a common component of buildings or enclosures that house gas turbines?

    <p>Fire detectors</p> Signup and view all the answers

    What is a benefit of using gas turbines in colder climates?

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

    What is the primary factor that affects the power rating of a gas turbine?

    <p>The temperature and humidity of the intake air</p> Signup and view all the answers

    Which of the following methods is most commonly used to improve the efficiency of the basic gas turbine cycle?

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

    How is the thermal efficiency of a gas turbine calculated?

    <p>By dividing the rated power by the fuel energy rate</p> Signup and view all the answers

    What is the role of the heat exchanger in the regeneration process?

    <p>It preheats the air between the compressor and the combustors</p> Signup and view all the answers

    What is the maximum efficiency a modern gas turbine can achieve in simple cycle mode?

    <p>35% - 40%</p> Signup and view all the answers

    What is the primary limitation of the open cycle gas turbine system?

    <p>It is less efficient than the closed cycle system</p> Signup and view all the answers

    What is the primary advantage of using intercooling in a gas turbine arrangement?

    <p>It makes more of the turbine power available to the output load, since isothermal compression takes less work than adiabatic compression.</p> Signup and view all the answers

    What is the effect of reheating in a gas turbine plant?

    <p>It increases the energy content of the gases and improves the thermal efficiency of the cycle.</p> Signup and view all the answers

    What is a benefit of using regeneration combined with intercooling in a gas turbine?

    <p>It increases the benefits of intercooling and makes pressure losses less significant.</p> Signup and view all the answers

    What type of heat exchanger is used for intercooling in a gas turbine arrangement?

    <p>A shell and tube heat exchanger.</p> Signup and view all the answers

    What is the purpose of reheating in a gas turbine plant?

    <p>To increase the exhaust heat and improve the thermal efficiency of the cycle.</p> Signup and view all the answers

    What is a disadvantage of using high-pressure ratio compressors in a gas turbine?

    <p>It increases the pressure losses and decreases the overall cycle efficiency.</p> Signup and view all the answers

    What is a primary disadvantage of using a high-pressure ratio compressor in a gas turbine system?

    <p>Significant losses through the intercooler</p> Signup and view all the answers

    How does intercooling affect the specific volume of the air in a gas turbine system?

    <p>It reduces the specific volume</p> Signup and view all the answers

    What is one of the benefits of combining intercooling with regeneration in a gas turbine setup?

    <p>Enhanced thermal efficiency</p> Signup and view all the answers

    In a gas turbine arrangement, what is the purpose of reheating the gases between stages?

    <p>To increase the energy content of the gases</p> Signup and view all the answers

    What drives the steam turbine in many combined cycle or cogeneration systems integrated with gas turbines?

    <p>Steam produced from the exhaust heat</p> Signup and view all the answers

    Why is utilizing the exhaust heat of a gas turbine important in combined cycle or cogeneration systems?

    <p>To improve overall system efficiency</p> Signup and view all the answers

    What is the primary reason for the reduced necessity of cycle improvements in modern gas turbines?

    <p>Advancements in combined cycle technology</p> Signup and view all the answers

    Which cycle improvement method increases the temperature of compressed air before combustion?

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

    What method is used to calculate the fuel energy rate in gas turbines?

    <p>Multiplying the fuel flow rate and the fuel heating value</p> Signup and view all the answers

    What is the main limitation of using high-pressure ratio compressors in a gas turbine?

    <p>Higher compressor discharge temperatures</p> Signup and view all the answers

    What is the primary function of intercoolers, regenerators, and/or reheaters in a gas turbine system?

    <p>To improve the basic efficiency of the gas turbine cycle</p> Signup and view all the answers

    What is the primary advantage of closed cycle gas turbine systems?

    <p>No fuel consumption, unlike open cycle systems</p> Signup and view all the answers

    What is the purpose of the diffuser in a centrifugal compressor?

    <p>To convert air velocity energy to pressure energy</p> Signup and view all the answers

    What percentage of the energy provided by fuel does a compressor use in a gas turbine?

    <p>Up to 65%</p> Signup and view all the answers

    In what direction does the air move inside an axial compressor?

    <p>Along the shaft</p> Signup and view all the answers

    What is the main advantage of a multi-stage centrifugal compressor over a single-stage one?

    <p>Higher pressure ratio</p> Signup and view all the answers

    What effect do fixed blades between rows of moving blades have on the air inside an axial compressor?

    <p>Slow the air down and raise the pressure</p> Signup and view all the answers

    Why are axial compressors preferred in the majority of large gas turbines?

    <p>Achieve higher compression ratios</p> Signup and view all the answers

    What percentage of the energy provided by the fuel is used by the compressor in a gas turbine?

    <p>Up to 65%</p> Signup and view all the answers

    What is the main difference between centrifugal and axial compressors?

    <p>Centrifugal compressors move the air radially, while axial compressors move the air axially.</p> Signup and view all the answers

    What is the purpose of the diffuser in a centrifugal compressor?

    <p>To convert the velocity energy to pressure energy</p> Signup and view all the answers

    Why are axial compressors preferred in the majority of large gas turbines?

    <p>Because they are more efficient and structurally sound</p> Signup and view all the answers

    What is the primary advantage of centrifugal compressors?

    <p>Simplicity and strength</p> Signup and view all the answers

    How do fixed blades affect the air inside an axial compressor?

    <p>They decelerate the air and raise the pressure</p> Signup and view all the answers

    What is the primary purpose of dilution air in the combustion chamber of a gas turbine?

    <p>To reduce the combustion temperature and impurities</p> Signup and view all the answers

    What type of combustor uses a single concentric flame tube?

    <p>Annular Combustor</p> Signup and view all the answers

    What percentage of the air entering the combustor is mixed with the fuel in the flame tube as combustion air?

    <p>20%</p> Signup and view all the answers

    What is the main function of the combustion chamber in a gas turbine?

    <p>To heat the compressed air before it enters the power turbine</p> Signup and view all the answers

    What is the role of the cooling air in the combustor?

    <p>It flows along the outside of the flame tube to cool the combustor</p> Signup and view all the answers

    What is the main advantage of an annular combustor design?

    <p>It is the most efficient use of the space available to the airflow</p> Signup and view all the answers

    What is the main difference between can-annular and annular combustors?

    <p>The main difference is in the way air is distributed to the combustor cans.</p> Signup and view all the answers

    What purpose do the interconnecting pipes serve in a can-annular combustor?

    <p>They carry the flame from one combustor to the other during the starting sequence.</p> Signup and view all the answers

    How many combustors in a can-annular arrangement have igniter elements?

    <p>Two combustors have igniter elements.</p> Signup and view all the answers

    What is the purpose of the outer casing in a can-annular combustor?

    <p>It allows for relative expansion of the combustor.</p> Signup and view all the answers

    What is the main function of the radial pins in a can-annular combustor?

    <p>They allow for relative expansion of the combustor.</p> Signup and view all the answers

    What is a significant disadvantage of the can combustor design in gas turbines?

    <p>Requires multiple igniters and fuel lines</p> Signup and view all the answers

    What is a unique feature of reverse flow can combustors in gas turbines?

    <p>Air flows to the end (top) of the combustor and then back toward the outlet</p> Signup and view all the answers

    Which statement best describes the behavior of air in the external casing of a single can combustor?

    <p>It absorbs heat, which improves combustion</p> Signup and view all the answers

    In heavy-duty industrial machines, where are the cans of a can combustor typically arranged?

    <p>Externally in a horizontal arrangement around the casing</p> Signup and view all the answers

    What is a significant difference between can-annular and annular combustors in gas turbines?

    <p>Annular combustors are more efficient in space utilization</p> Signup and view all the answers

    What is the primary role of dilution air in a gas turbine combustor?

    <p>To cool the combustion gases</p> Signup and view all the answers

    What is the main benefit of using aero-derivative gas turbines in offshore applications?

    <p>Improved structural strength and easier maintenance access</p> Signup and view all the answers

    Which of the following statements best describes intercooling in a gas turbine system?

    <p>Increases the specific volume of the air</p> Signup and view all the answers

    What is the purpose of a power turbine in an aero-derivative gas turbine?

    <p>To provide rotational energy for powering other equipment</p> Signup and view all the answers

    Which of the following is a difference between aero-derivative and heavy-duty gas turbines?

    <p>Heavy-duty gas turbines have a more complex design</p> Signup and view all the answers

    How does a combustor in a gas turbine achieve heating of the compressed air?

    <p>By heating the compressed air before it enters the power turbine</p> Signup and view all the answers

    What is the purpose of the cooling air in a gas turbine combustor?

    <p>To cool the power turbine blades</p> Signup and view all the answers

    What is the temperature range of the combustion flame in a gas turbine combustor?

    <p>1500 to 2000°C</p> Signup and view all the answers

    Why do some parts of the cooling air re-enter the flame tube in a gas turbine combustor?

    <p>To dilute the mixture in the flame tube</p> Signup and view all the answers

    What design is the most efficient use of space available to airflow in a gas turbine combustor?

    <p>Annular Combustor</p> Signup and view all the answers

    What is the main benefit of using single concentric flame 'tube' in an annular combustor design?

    <p>Efficient use of available space</p> Signup and view all the answers

    What is a unique advantage of annular combustion chambers in aircraft engines?

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

    Which aspect of the can combustor design minimizes problems associated with non-uniform outlet temperatures?

    <p>External mounting</p> Signup and view all the answers

    In a can combustor system, what is the purpose of the swirl plate?

    <p>To mix air and fuel</p> Signup and view all the answers

    How is the air flow direction described in an external reverse flow can combustor design?

    <p>Inward towards the turbine</p> Signup and view all the answers

    What contributes to the minimization of flow resistance in an annular combustion chamber?

    <p>Even distribution of combustion</p> Signup and view all the answers

    How is the combustion air supplied to the can combustor in the external reverse flow design?

    <p>From the compressor outlet</p> Signup and view all the answers

    What is a key disadvantage of can combustors in comparison to annular combustors?

    <p>Not the most efficient use of space</p> Signup and view all the answers

    What distinguishes the airflow path in a straight-through can combustor?

    <p>Exits at the inlet end</p> Signup and view all the answers

    How do air crossover tubes benefit multiple can combustors in a system?

    <p>Help maintain equal operating conditions</p> Signup and view all the answers

    What allows for easier maintenance access and greater strength in some external can combustor designs?

    <p>External mounting angle</p> Signup and view all the answers

    How is air distributed to the combustor cans in a can-annular combustor arrangement?

    <p>From a common annular space between inner and outer air casings through scoops and holes</p> Signup and view all the answers

    What is the primary function of the radial pins in a can-annular combustor?

    <p>To allow relative expansion between the inner chamber and the outer casing</p> Signup and view all the answers

    What role do interconnecting pipes play in a can-annular combustor arrangement?

    <p>To ensure uniform combustion conditions and carry the flame from one combustor to another during starting sequence</p> Signup and view all the answers

    Which statement best describes the cooling air distribution in a can-annular combustor?

    <p>The cooling air is supplied through holes in the combustors</p> Signup and view all the answers

    What is the significance of having only two combustors with igniter elements in a can-annular combustor?

    <p>To maintain combustion stability by using a limited number of ignition elements</p> Signup and view all the answers

    What type of material are conventional gas turbine nozzles cast with?

    <p>Nickel-based super alloys</p> Signup and view all the answers

    Why are gas turbine blades usually replaced at fixed intervals?

    <p>To avoid catastrophic blade failure</p> Signup and view all the answers

    What is the main function of blade cooling in gas turbines?

    <p>To decrease metal temperature and increase blade life</p> Signup and view all the answers

    Which type of gas turbine blade cooling often uses air-circulation?

    <p>Air-cooled blades</p> Signup and view all the answers

    What is the greatest challenge in gas turbine materials?

    <p>Managing materials in the turbine nozzles and blades</p> Signup and view all the answers

    Why do gas turbine rotors withstand high stresses?

    <p>Because of high gas temperatures and rotational speeds</p> Signup and view all the answers

    What is the primary purpose of the power turbine in a gas turbine system?

    <p>Provide mechanical power for the generator</p> Signup and view all the answers

    In axial-flow turbines, what is the function of the nozzles?

    <p>Increase pressure and temperature</p> Signup and view all the answers

    What distinguishes power turbines from compressors in a gas turbine system?

    <p>Have a higher number of stages</p> Signup and view all the answers

    Which statement is true regarding power turbines operating at high temperatures?

    <p>Undergo large rotational stresses</p> Signup and view all the answers

    What is the main function of the moving blades in the axial-flow turbine?

    <p>Decrease pressure and temperature</p> Signup and view all the answers

    How does an impulse turbine different from a reaction turbine in terms of nozzle action?

    <p>Impulse turbines convert pressure energy into velocity energy</p> Signup and view all the answers

    What is the primary reason for incorporating complicated cooling passages in turbine nozzles and blades?

    <p>To reduce metal temperature and increase life</p> Signup and view all the answers

    What is the typical material used to make turbine rotors?

    <p>Heat resisting steel</p> Signup and view all the answers

    What is the phenomenon that occurs in metals at very high temperatures and stresses, causing them to stretch and weaken?

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

    What is the purpose of replacing turbine blades at fixed intervals?

    <p>To prevent catastrophic failure due to creep</p> Signup and view all the answers

    What is the advantage of using ceramic components in turbine blades?

    <p>They allow for a significant increase in firing temperatures</p> Signup and view all the answers

    What is the material used to cast conventional nozzles?

    <p>Special nickel-based super alloys</p> Signup and view all the answers

    What percentage of the power from the hot gases is used to drive the compressor?

    <p>Up to 65%</p> Signup and view all the answers

    What is the primary function of the nozzles in an axial-flow turbine?

    <p>To increase the velocity of the hot gases</p> Signup and view all the answers

    What is the primary difference between impulse and reaction turbines?

    <p>The way nozzles convert energy</p> Signup and view all the answers

    What is the primary reason for the high blade loads in power turbines?

    <p>High velocity of the hot gases</p> Signup and view all the answers

    What is a characteristic of the stages in an axial-flow turbine?

    <p>A row of rotating and stationary blades</p> Signup and view all the answers

    What is the purpose of the rotating blades in an axial-flow turbine?

    <p>To extract power with a further drop in pressure and temperature</p> Signup and view all the answers

    What is the purpose of the acceleration fuel flow schedule in a gas turbine control system?

    <p>To override the governor error signal during acceleration</p> Signup and view all the answers

    What is monitored in a gas turbine control system to detect excessive vibration?

    <p>Accelerometers or eddy-current displacement probes</p> Signup and view all the answers

    What is the purpose of the automatic emergency trip system in a gas turbine control system?

    <p>To close the main fuel shutoff valve in case of emergency</p> Signup and view all the answers

    What is the purpose of the operator interface in a gas turbine control system?

    <p>To allow the operator to startup, shutdown, or modify the control system logic</p> Signup and view all the answers

    What is protected against by the protective devices in a gas turbine control system?

    <p>Power turbine overspeed, excessive vibration, and other conditions</p> Signup and view all the answers

    What is the purpose of the instrumentation in a gas turbine control system?

    <p>To monitor various parameters of the gas turbine</p> Signup and view all the answers

    What type of fuel system does the dual-shaft gas turbine control system configuration vary according to?

    <p>Gaseous fuel system</p> Signup and view all the answers

    Which component in the system establishes a speed reference setting in the reset mechanism?

    <p>Loading station</p> Signup and view all the answers

    What is the purpose of the reset mechanism in the governor?

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

    What role do override trims play in the governor reset mechanism?

    <p>They protect the gas producer from over temperature and overspeed</p> Signup and view all the answers

    What is the function of the metering valve positioner in the system?

    <p>To reposition the fuel metering valve until the error is eliminated</p> Signup and view all the answers

    What is the role of the pressure regulator in the gas fired system?

    <p>To supply pressurized gas to the gas supply line</p> Signup and view all the answers

    What parameter is continuously monitored and controlled for a gas turbine using vibration sensors?

    <p>Bearing temperatures</p> Signup and view all the answers

    In a gas turbine control system, acceleration fuel flow schedule is based on the rise in _____________.

    <p>Compressor outlet pressure</p> Signup and view all the answers

    What is the main purpose of the operator interface in a gas turbine control system?

    <p>To startup or shutdown the gas turbine</p> Signup and view all the answers

    What system is automatically initiated when there is an increase in demand for power in a gas turbine setup?

    <p>Backup power generation unit</p> Signup and view all the answers

    Which of the following would be a cause for the automatic shutdown of a gas turbine due to protection systems?

    <p>Exhaust gas temperature exceeding the maximum limit</p> Signup and view all the answers

    What is the primary role of an emergency trip system in a gas turbine control setup?

    <p>To close the main fuel shutoff valve under specific conditions</p> Signup and view all the answers

    What is the function of the reset mechanism in the governor of a gas turbine control system?

    <p>It determines the position of the fuel metering valve and controls the engine fuel flow.</p> Signup and view all the answers

    What is the primary purpose of the fuel metering valve in a gas turbine control system?

    <p>It regulates the supply of pressurized fuel to the combustors.</p> Signup and view all the answers

    How does the governor system respond to changes in engine speed in a gas turbine control system?

    <p>It maintains a constant engine speed by adjusting the fuel flow to the burners.</p> Signup and view all the answers

    What is the role of the pressure regulator in the gas fired system of a gas turbine?

    <p>It ensures the fuel pressure remains constant regardless of demand.</p> Signup and view all the answers

    What is the purpose of the override trims applied on the governor reset mechanism in a gas turbine control system?

    <p>They produce an artificial error signal until an adverse condition is overcome.</p> Signup and view all the answers

    What is the effect of an error signal in the governor of a gas turbine control system?

    <p>It repositions the fuel metering valve to maintain a constant engine speed.</p> Signup and view all the answers

    What is the primary factor affecting the efficiency and power output of a gas turbine?

    <p>The compression ratio across the compressor</p> Signup and view all the answers

    Why is an increase in turbine inlet temperature beneficial for gas turbine efficiency?

    <p>Allows more work to be done with the same amount of air</p> Signup and view all the answers

    In gas turbine design, what is the main focus in order to achieve high efficiency in the cycle?

    <p>Improving combustion and turbine materials</p> Signup and view all the answers

    What is a key consideration when determining the maximum power achievable by a gas turbine?

    <p>The expected life of hot gas path components</p> Signup and view all the answers

    When might a user be inclined to accept higher maintenance costs in a gas turbine system?

    <p>For peak power generation during short periods</p> Signup and view all the answers

    Why is operating at maximum power not preferred for base load operation in a gas turbine system?

    <p>To lower the risk of failure</p> Signup and view all the answers

    What is the unit of measurement for heat rate in a gas turbine?

    <p>MJ/kWh</p> Signup and view all the answers

    What is the effect of decreasing inlet air temperature on the power produced by a gas turbine?

    <p>Power output increases</p> Signup and view all the answers

    What is the power output of the gas turbine at an ambient air temperature of 45°C?

    <p>6600 kW</p> Signup and view all the answers

    What is the relationship between the power produced by a gas turbine and the mass airflow?

    <p>Power is directly proportional to mass airflow</p> Signup and view all the answers

    What is the purpose of using heat exchangers in gas turbines?

    <p>To increase power output</p> Signup and view all the answers

    What is the rated power at standard conditions of 15°C?

    <p>9500 kW</p> Signup and view all the answers

    What is the primary factor in determining efficiency and power in a gas turbine?

    <p>Turbine inlet temperature</p> Signup and view all the answers

    What is the typical efficiency range of a simple cycle gas turbine?

    <p>30-40%</p> Signup and view all the answers

    What is the maximum power that can be achieved in a gas turbine a function of?

    <p>Life expected of the hot gas path components</p> Signup and view all the answers

    What is the primary advantage of combined cycle applications in gas turbine plants?

    <p>Total efficiency exceeding 60%</p> Signup and view all the answers

    Why is maximum power not desirable for base load operation?

    <p>It increases the risk of failure and maintenance costs</p> Signup and view all the answers

    What is the tradeoff often used for peak power generation?

    <p>Higher maintenance costs for increased power output</p> Signup and view all the answers

    What is the primary factor that affects the power output of a gas turbine?

    <p>Inlet air temperature</p> Signup and view all the answers

    What is the unit of measurement for heat rate input in a gas turbine?

    <p>MJ/kWh</p> Signup and view all the answers

    At what inlet air temperature is the power output of the gas turbine approximately 12 000 kW?

    <p>-30°C</p> Signup and view all the answers

    What is the effect of decreasing inlet air temperature on the mass airflow through the engine?

    <p>It increases</p> Signup and view all the answers

    What is the relationship between the power produced by a gas turbine and the mass flow?

    <p>The power is directly proportional to the mass flow</p> Signup and view all the answers

    What is the rated power of the gas turbine at standard conditions of 15°C?

    <p>9500 kW</p> Signup and view all the answers

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