Centennial College - SDRE: ESET 223 15 Lubrication Systems Gravity-Fed
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Questions and Answers

In which type of turbine is the kinetic energy of steam (impulse force) used to rotate the turbine?

  • Steam turbine
  • Impulse turbine (correct)
  • Combined turbine
  • Reaction turbine

    • What type of force is used to rotate the turbine in an impulse turbine?

  • Reaction force
  • Impulsive force (correct)
  • Kinetic force
  • Pressure force

    • What is the basis of difference between impulse and reaction turbines?

  • Direction of steam flow
  • Number of blades
  • Type of steam used
  • Force used to turn the turbine (correct)

    • What is the function of guide blades in a reaction turbine?

    <p>To guide steam flow over the turbine</p> Signup and view all the answers

    What happens to the pressure of steam in an impulse turbine while flowing over moving blades?

    <p>It remains unchanged</p> Signup and view all the answers

    What happens to the pressure of steam in a reaction turbine while flowing over the blades?

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

    In which type of turbine does the pressure of steam decrease in the nozzle before entering the turbine?

    <p>Impulse turbine</p> Signup and view all the answers

    What type of energy of steam is used to turn the turbine in a reaction turbine?

    <p>Pressure energy</p> Signup and view all the answers

    In an impulse turbine, how is the steam guided to flow over the turbine?

    <p>Through a nozzle</p> Signup and view all the answers

    What type of force on the blades rotates the turbine in a reaction turbine?

    <p>Reaction force</p> Signup and view all the answers

    What is the main purpose of using a condensing steam turbine?

    <p>To turn the steam at least partly to water using condensers and giant concrete cooling towers</p> Signup and view all the answers

    What would happen if the exhaust steam from a noncondensing steam turbine is allowed to go to waste into the atmosphere?

    <p>The thermal efficiency of the turbine would decrease</p> Signup and view all the answers

    What is the role of a noncondensing steam turbine in heating water for a paper mill?

    <p>To use the exhaust steam to heat feedwater in an open feedwater heater</p> Signup and view all the answers

    Why do condensing steam turbines operate with an exhaust pressure of 26" Hg to 29" Hg vacuum?

    <p>To allow the steam to expand more and extract more energy</p> Signup and view all the answers

    What distinguishes a condensing steam turbine from a noncondensing steam turbine?

    <p>The presence of a condenser and giant concrete cooling towers</p> Signup and view all the answers

    Why must noncondensing steam turbines use a large amount of the available exhaust steam to maintain maximum efficiency?

    <p>To prevent condensation of the steam</p> Signup and view all the answers

    What is the significance of an increase in vacuum on the exhaust of a steam turbine?

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

    What happens if a noncondensing steam turbine's exhaust steam is allowed to go to waste into the atmosphere?

    <p>The thermal efficiency of the turbine would decrease</p> Signup and view all the answers

    What is a characteristic of noncondensing steam turbines?

    <p>They have no condensate returns</p> Signup and view all the answers

    What distinguishes condensing turbines from noncondensing turbines?

    <p>The presence of a condenser and giant concrete cooling towers</p> Signup and view all the answers

    In force-fed lubrication systems for large steam turbines, why must the lubricating oil be cooled?

    <p>To prevent the oil from breaking down and losing its lubricating ability</p> Signup and view all the answers

    What is the purpose of the centrifuge in force-fed lubrication systems for steam turbines?

    <p>To remove dirt and water from the lubricating oil</p> Signup and view all the answers

    What role does a mechanical governor play in steam turbines?

    <p>Maintaining a constant speed of rotation for the steam turbine</p> Signup and view all the answers

    Which type of steam turbine exhausts at atmospheric pressure or above?

    <p>Noncondensing steam turbine</p> Signup and view all the answers

    What is the function of a ring in gravity-fed lubrication systems for bearings on steam turbines?

    <p>To pick up oil and deposit it onto the shaft for bearing lubrication</p> Signup and view all the answers

    Why must the lubricating oil coolers be periodically dismantled and cleaned in force-fed lubrication systems for steam turbines?

    <p>To remove scale and impurities from the tubes and shell</p> Signup and view all the answers

    What happens if the centrifugal force exceeds the centripetal force in a steam turbine?

    <p>The turbine will self-destruct</p> Signup and view all the answers

    What is the function of an overspeed trip device in a steam turbine?

    <p>To shut off the steam supply if the turbine exceeds its rated speed</p> Signup and view all the answers

    What is the purpose of an adjustable spring in a mechanical overspeed trip mechanism for a steam turbine?

    <p>To hold a bolt in position until shaft speed overcomes its tension</p> Signup and view all the answers

    What is the primary function of a hydraulic governor in a steam turbine?

    <p>To control and maintain a constant speed of rotation for the turbine</p> Signup and view all the answers

    In an impulse turbine, what converts the pressure of steam into kinetic energy?

    <p>Nozzles attached to the casing</p> Signup and view all the answers

    Why is the speed of reaction turbine much lower than that of an impulse turbine?

    <p>Steam velocity is lower in reaction turbine</p> Signup and view all the answers

    What is the purpose of the fixed blades in a reaction turbine?

    <p>To convert steam pressure into kinetic energy</p> Signup and view all the answers

    What type of steam turbine is used in plants where there is an abundance of low-pressure steam?

    <p>Mixed-pressure steam turbine</p> Signup and view all the answers

    What is the purpose of a double-flow steam turbine?

    <p>To balance the axial thrust on the rotor</p> Signup and view all the answers

    What is the function of extraction steam turbines?

    <p>To use steam withdrawn from a stage of the turbine for process or feedwater heating</p> Signup and view all the answers

    Why is the proper lubricating oil essential for steam turbine operation?

    <p>To prevent wear from friction on the turbine rotor</p> Signup and view all the answers

    What is the purpose of ring oilers in small auxiliary steam turbines?

    <p>To supply lubricating oil to bearing grooves for even distribution over bearing surfaces</p> Signup and view all the answers

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