Steam Boilers Overview
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Steam Boilers Overview

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Questions and Answers

What is a primary advantage of water tube boilers compared to fire tube boilers?

  • Safer due to lower pressures
  • Lower initial cost
  • Larger shell diameter for capacity
  • Higher operating pressure (correct)

    • Which characteristic is true for water tube boilers?

  • Less suitable for power generation
  • Internally fired
  • Requires water treatment (correct)
  • Uses a large shell for capacity

    • Which of the following boilers is more suitable for mobile applications?

  • Neither is suitable
  • Fire tube boilers (correct)
  • Both are equally suitable
  • Water tube boilers

    • What is a disadvantage of water tube boilers compared to fire tube boilers?

    <p>Necessary water treatment</p> Signup and view all the answers

    What is a significant characteristic of fire tube boilers?

    <p>Low steam production rates</p> Signup and view all the answers

    What is a key reason for having boiler mountings?

    <p>To provide safety mechanisms</p> Signup and view all the answers

    Which application is water tube boilers ideally suited for?

    <p>Power generation</p> Signup and view all the answers

    Which of the following is NOT an advantage of water tube boilers?

    <p>Lower initial cost</p> Signup and view all the answers

    What is the primary purpose of a fusible plug in a boiler?

    <p>To extinguish fire when water levels are low</p> Signup and view all the answers

    What shape is the manhole in a boiler?

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

    Which of the following is NOT a function of the economizer?

    <p>Generate steam directly</p> Signup and view all the answers

    Which of the following is an accessory used to preheat the air supplied to the furnace of the boiler?

    <p>Air preheater</p> Signup and view all the answers

    Which of the following accessories is used to separate steam from water?

    <p>Steam separator</p> Signup and view all the answers

    What is the general purpose of boiler accessories?

    <p>To improve efficiency of the boiler</p> Signup and view all the answers

    Why are boiler accessories not considered mandatory?

    <p>They are not mounted directly on the boiler</p> Signup and view all the answers

    What is the main benefit of using an economizer in a boiler system?

    <p>Reduces heating costs</p> Signup and view all the answers

    What is the primary function of a boiler?

    <p>To generate and supply steam at a constant pressure</p> Signup and view all the answers

    Which type of boiler uses tubes to lead hot flue gases through water?

    <p>Fire tube boiler</p> Signup and view all the answers

    Which classification of boilers is determined by the location of the furnace?

    <p>Internally fired boiler</p> Signup and view all the answers

    What distinguishes natural circulation boilers from forced circulation boilers?

    <p>The method of water circulation</p> Signup and view all the answers

    Which type of boiler can utilize gaseous fuels according to its classification?

    <p>Gaseous fueled boiler</p> Signup and view all the answers

    In what configuration is a boiler if the furnace is located inside the shell?

    <p>Internally fired boiler</p> Signup and view all the answers

    Which boiler type is considered stationary?

    <p>Lancashire boiler</p> Signup and view all the answers

    What is a distinguishing characteristic of water tube boilers?

    <p>They have flue gases flowing through water</p> Signup and view all the answers

    What is the primary function of the tubes in a water tube boiler?

    <p>To allow water to flow while hot gases pass around them</p> Signup and view all the answers

    What is the maximum steam pressure that can be achieved using a Babcock and Wilcox boiler?

    <p>75 – 80 bar</p> Signup and view all the answers

    In which application are Babcock and Wilcox boilers primarily used?

    <p>Thermal power stations</p> Signup and view all the answers

    Which component of the Babcock and Wilcox boiler helps measure steam pressure?

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

    Which of the following is NOT a component typically associated with a Babcock and Wilcox boiler?

    <p>Heat exchanger</p> Signup and view all the answers

    What distinguishes a water tube boiler from a fire tube boiler?

    <p>Water in tubes and hot gases outside</p> Signup and view all the answers

    What role does the mud box play in a water tube boiler?

    <p>It collects sediment and impurities from water</p> Signup and view all the answers

    Which of the following components is responsible for regulating water flow in a water tube boiler?

    <p>Feed check valve</p> Signup and view all the answers

    What is the purpose of an air pre-heater in a boiler system?

    <p>To preheat the air for improved combustion efficiency</p> Signup and view all the answers

    How does a super heater function in a boiler?

    <p>It raises the temperature of steam above the saturation point</p> Signup and view all the answers

    What is the primary function of a steam trap?

    <p>To drain condensed water while retaining pressure steam</p> Signup and view all the answers

    Where is a steam separator typically installed?

    <p>Close to the turbine room</p> Signup and view all the answers

    What is the effect of preheating air on the combustion process?

    <p>It improves boiler efficiency</p> Signup and view all the answers

    Which component ensures that pressure steam does not escape while draining water?

    <p>Steam trap</p> Signup and view all the answers

    What is one of the primary benefits of using a super heater in a boiler?

    <p>It increases steam's thermal efficiency</p> Signup and view all the answers

    Which statement accurately describes the function of a steam separator?

    <p>It removes entrained water droplets from steam</p> Signup and view all the answers

    Study Notes

    Definition and Function of Boilers

    • A boiler is a closed metallic vessel that converts water into steam under pressure through heat generated by fuel combustion.
    • Boilers generate and supply steam at a constant pressure, which can be dry, wet, or superheated.

    Classification of Boilers

    • By Axis of Shell
      • Horizontal, Vertical, and Inclined boilers.
    • By Application
      • Stationary boilers (fixed) and Mobile boilers (portable).
    • By Furnace Location
      • Internally fired (furnace inside the shell) and Externally fired (furnace outside the shell).
    • By Fuel Type
      • Solid, Liquid, and Gaseous fueled boilers.
    • By Water Circulation Method
      • Natural circulation (temperature difference) and Forced circulation (using pumps).
    • By Water and Flue Gas Flow
      • Fire tube (hot gases in tubes) and Water tube (water in tubes).

    Fire Tube vs. Water Tube Boilers

    • Fire Tube Boilers
      • Hot flue gases pass through tubes surrounded by water (e.g., Lancashire boiler).
    • Water Tube Boilers
      • Water flows through tubes, and hot flue gases pass around them (e.g., Babcock and Wilcox Boiler).

    Babcock & Wilcox Boiler

    • A horizontal, stationary, externally fired, natural circulation water tube boiler.
    • Capable of producing steam at pressures up to 75-80 bar, widely used in thermal power stations.

    Advantages of Water Tube Boilers

    • Rapid steam generation and higher pressure capabilities.
    • Higher steam generation capacity, less sediment deposition.
    • Suitable for various fuel types, compact size, and easier maintenance.

    Disadvantages of Water Tube Boilers

    • Not suitable for mobile applications; requires water treatment.
    • Higher initial costs compared to fire tube boilers.

    Fire Tube and Water Tube Boiler Comparison

    • Fire tube boilers operate at low pressure (up to 15 bar), while water tube boilers can operate at high pressure (up to 75 bar).
    • Fire tube boilers are safer due to lower pressure but are less efficient in steam production than water tube boilers.

    Boiler Mountings and Accessories

    • Mountings are essential for control over steam generation, safety, and measurement.
    • Fusible Plug: Extinguishes fire when water levels drop too low, prevents overheating damage.
    • Manhole: Oval-shaped opening for inspection and cleaning.

    Boiler Accessories

    • Improve efficiency; not mandatory and not mounted directly on the boiler.
    • Include: Economizer, Air preheater, Superheater, Steam separator, and Steam trap.

    Functions of Boiler Accessories

    • Economizer: Raises feed water temperature using flue gas waste heat.
    • Air Preheater: Preheats air for combustion to enhance boiler efficiency.
    • Superheater: Increases steam temperature beyond saturation, boosting enthalpy.
    • Steam Trap: Drains condensed water while retaining pressure in steam lines.
    • Steam Separator: Removes water droplets from steam before entering turbine.

    Conclusion

    • Boilers play a critical role in steam generation and power generation, with various classifications and accessories enhancing their functionality and efficiency. Understanding the differences between fire tube and water tube boilers is essential for selection based on operational requirements.

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    Description

    Explore the fundamentals of steam boilers, including their definitions and functions. Understand how these essential components convert water into steam using heat from combustion. This quiz is tailored for students in mechanical engineering or those interested in industrial applications.

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