Power plant engineering, Exercises of Mechanical Engineering

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Typology: Exercises

2021/2022

Uploaded on 01/21/2022

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1. It is fitting which is necessary for the operation and safety of a boiler
It is installed below the boiler’s water level, to extinguish a fire in the event of water level in the
boiler shell falling below a certain specified limit
2.
direct method:
• Does not give clues to the operator as to why the efficiency of a system is lower
• Does not calculate various losses accountable for various efficiency levels
Indirect Method:
• Drawbacks in direct method overcome by indirect method it’s also called as heat loss
method.
Measure all the losses associated with the boilers, and subtracting from 100 give the
boiler efficiency
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  1. It is fitting which is necessary for the operation and safety of a boiler It is installed below the boiler’s water level, to extinguish a fire in the event of water level in the boiler shell falling below a certain specified limit

direct method:

  • Does not give clues to the operator as to why the efficiency of a system is lower
  • Does not calculate various losses accountable for various efficiency levels Indirect Method:
  • Drawbacks in direct method overcome by indirect method it’s also called as heat loss method.
  • Measure all the losses associated with the boilers, and subtracting from 100 give the boiler efficiency

• Boiler efficiency is a measure of how effectively chemical

energy in fuel is converted into heat energy in steam going

to the turbines but,

• it is ratio of amount of steam generated to the amount fuel

consumed by boiler

  1. The small pressure difference which cause a flow of gas to take place in the steam power plant called draught. The main objectives of producing draught in a boiler are: - To provide an adequate supply of air for the fuel combustion
  • To exhaust the gases of combustion from the combustion chamber
  • To discharge these gases to the atmosphere through the chimney
    • In the fire tube boilers, the hot gases are inside the tubes and the water surrounds the tubes.
      • Examples: Cochran, Lancashire and Loco motive boilers.
    • In the water tube boilers, the water is inside the tubes and hot gases surround them.
      • Examples: Babcock and Wilcox boiler
    • Blow down necessary in maintaining the optimum level of total dissolved solids (TDS) in the boiler water.
    • It is necessary to protect the surfaces of the heat exchanger in the boiler
    • Economizer: the waste heat of the flue gases is utilized for heating of feed water or any other.
    • Air Pre-heater: The function of the air pre-heater is to increase the temperature of air before it enters the furnace. ▪ It is placed after the economizer. ▪ Flue gases pass through the economizer and then to the air preheater