Podcast
Questions and Answers
What is the primary method of water circulation in a natural circulation boiler?
What is the primary method of water circulation in a natural circulation boiler?
- Forced by pumps
- Due to temperature difference (correct)
- Through vacuum formation
- By mechanical agitation
Which of the following statements is true about fire tube boilers?
Which of the following statements is true about fire tube boilers?
- They are primarily designed for rapid steam generation.
- They can operate at pressures above 20 bar.
- They use hot flue gases to heat water surrounding the tubes. (correct)
- They circulate water inside tubes.
What distinguishes water tube boilers from fire tube boilers?
What distinguishes water tube boilers from fire tube boilers?
- Gases pass through the tubes while water circulates outside.
- Water circulates inside the tubes with gases passing around them. (correct)
- They are less efficient than fire tube boilers.
- Water is circulated externally to the tubes.
Which boiler type is more suitable for generating steam at very high pressures?
Which boiler type is more suitable for generating steam at very high pressures?
Which boiler examples are categorized as fire tube boilers?
Which boiler examples are categorized as fire tube boilers?
What is a characteristic feature of the Babcock and Wilcox boiler?
What is a characteristic feature of the Babcock and Wilcox boiler?
What is the function of the chain grate stocker in a steam boiler?
What is the function of the chain grate stocker in a steam boiler?
How is water introduced into the boiler drum?
How is water introduced into the boiler drum?
What is the maximum steam pressure that a high capacity Babcock and Wilcox boiler can produce?
What is the maximum steam pressure that a high capacity Babcock and Wilcox boiler can produce?
What initiates the circulation of water within the boiler?
What initiates the circulation of water within the boiler?
Which of the following boilers is suited for quick steam raising?
Which of the following boilers is suited for quick steam raising?
What is the flow path of the flue gases in a steam boiler?
What is the flow path of the flue gases in a steam boiler?
What happens to the steam-water mixture from the water tubes in the boiler?
What happens to the steam-water mixture from the water tubes in the boiler?
What role do the baffle plates serve in the path of flue gases?
What role do the baffle plates serve in the path of flue gases?
What is the primary function of the steam stop valve?
What is the primary function of the steam stop valve?
Where is the upper junction box of the super heater tubes connected?
Where is the upper junction box of the super heater tubes connected?
What primarily governs the time for coal to burn in the chain grate stocker?
What primarily governs the time for coal to burn in the chain grate stocker?
How does the blow off valve contribute to boiler maintenance?
How does the blow off valve contribute to boiler maintenance?
What unique feature does the feed check valve possess?
What unique feature does the feed check valve possess?
What triggers the operation of the fusible plug?
What triggers the operation of the fusible plug?
What is the purpose of the manhole in the boiler?
What is the purpose of the manhole in the boiler?
Where is the mud box located in relation to the boiler system?
Where is the mud box located in relation to the boiler system?
What is one of the primary functions of boiler accessories?
What is one of the primary functions of boiler accessories?
Which component is specifically designed to prevent water from flowing back into the feed pump?
Which component is specifically designed to prevent water from flowing back into the feed pump?
What is the primary purpose of the super heater in a water tube boiler?
What is the primary purpose of the super heater in a water tube boiler?
How do water tube boilers compare to fire tube boilers in terms of steam generation speed?
How do water tube boilers compare to fire tube boilers in terms of steam generation speed?
What advantage do water tube boilers have over fire tube boilers regarding pressure?
What advantage do water tube boilers have over fire tube boilers regarding pressure?
What is a major advantage of water tube boilers concerning evaporation rates?
What is a major advantage of water tube boilers concerning evaporation rates?
What is the primary cause of lower sediment deposition in water tube boilers?
What is the primary cause of lower sediment deposition in water tube boilers?
Which component is essential for controlling superheated steam flow in a boiler system?
Which component is essential for controlling superheated steam flow in a boiler system?
What is one common disadvantage of fire tube boilers compared to water tube boilers?
What is one common disadvantage of fire tube boilers compared to water tube boilers?
In a water tube boiler, what typically happens to steam when it is not required?
In a water tube boiler, what typically happens to steam when it is not required?
What is the primary function of an economizer in a boiler system?
What is the primary function of an economizer in a boiler system?
Which accessory is specifically used to enhance combustion efficiency by preheating air?
Which accessory is specifically used to enhance combustion efficiency by preheating air?
Why is superheated steam necessary in thermal power generation?
Why is superheated steam necessary in thermal power generation?
What role does a steam separator play in a boiler system?
What role does a steam separator play in a boiler system?
Where is an air preheater typically located in relation to other boiler components?
Where is an air preheater typically located in relation to other boiler components?
What is the effect of using an economizer on fuel consumption in a boiler?
What is the effect of using an economizer on fuel consumption in a boiler?
Which accessory is essential for maintaining dry steam conditions in steam turbines?
Which accessory is essential for maintaining dry steam conditions in steam turbines?
What is a disadvantage of using wet steam in a steam turbine?
What is a disadvantage of using wet steam in a steam turbine?
Study Notes
Boiler Classification
- Boilers are categorized based on circulation methods: Natural Circulation (due to temperature difference) and Forced Circulation (using pumps).
- Another classification is based on the arrangement of water and flue gases: Fire Tube Boilers and Water Tube Boilers.
Fire Tube Boilers
- Hot flue gases circulate through tubes while water surrounds these tubes.
- Common types include:
- Cochran boiler
- Cornish boiler
- Lancashire boiler
- Locomotive boiler
- Scotch Marine boiler
- Suitable for steady working pressures up to 20 bar.
Water Tube Boilers
- Water circulates inside tubes, with hot gases passing around externally.
- Examples include:
- Babcock and Wilcox boiler
- Stirling boiler
- Yarrow boiler
- Better suited for high pressure steam generation and rapid steam production.
Babcock & Wilcox Boiler
- Type of horizontal, externally fired, natural circulation water tube boiler.
- Capable of producing steam at up to 80 bar.
- Features a superheater with U-tubes located in the combustion chamber.
Water Circuit
- Water enters the boiler drum via a feed valve, maintaining a constant level.
- Heated water descends into headers, ascending in inclined tubes due to decreased density.
- Continuous circulation established between the boiler drum and the water tubes.
Flue Gas Path
- Hot gases pass upwards and downwards around water tubes before exiting through the chimney.
- Direct contact with hot gases leads to efficient heating and evaporation of water in the tubes.
Superheating of Steam
- Steam from the boiler drum is directed to a superheater for increased temperature.
- Superheated steam is essential for thermal power generation to avoid turbine corrosion.
Advantages of Water Tube Boilers
- Quicker steam production: Lower water content allows for rapid steam generation.
- Higher pressure capacity: Ability to withstand extreme pressures due to no tubes inside the boiler drum.
- Increased evaporation rate: More heating surface area leads to higher evaporation rates, making it suitable for large power plants.
- Less sediment deposition: Improved circulation minimizes the likelihood of sediment buildup.
Boiler Components
- Steam Stop Valve: Regulates steam flow; opened/closed by rotating a handle.
- Blow Off Valve: Removes sediment from the boiler; essential for maintenance.
- Feed Check Valve: Non-return valve regulating water flow; prevents backflow to the drum.
- Fusible Plug: Safety device that extinguishes fire when water level drops too low.
- Man Hole & Mud Box: Enhances access for maintenance and sediment removal, respectively.
Boiler Accessories
- Accessories serve to improve boiler efficiency and performance, installed outside the boiler drum.
- Key accessories include:
- Economizer: Preheats feed water using leftover heat from flue gases, reducing fuel consumption.
- Air Preheater: Preheats air supplied to the furnace for improved combustion efficiency.
- Superheater: Increases steam temperature beyond saturation, preventing condensation in turbines.
- Steam Separator: Removes water particles from steam before it enters the turbine, enhancing efficiency.
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Description
Explore the various classifications of boilers, including natural and forced circulation types, as well as the differences between fire tube and water tube boilers. This quiz will test your understanding of how these systems operate based on the principles of working and the flow of water and flue gases.
