STEAM BOILERS AND PERFORMANCE

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• Q1: What is a Boiler?
  Ans: A boiler is a closed vessel in which water is heated by using fuel. The heat produced by burning fuel converts water into steam. This steam is then used for different purposes such as running engines, turbines, or for heating.
• Q2: What is a Steam Boiler?
  Ans: A steam boiler is a type of boiler that produces steam at a required pressure by heating water. It is mainly used in power plants, industries, and steam engines to generate power.
• Q3: Define Space Space.
  Ans: Space space (also called steam space) is the upper empty portion of a boiler drum where steam collects after being formed. It separates steam from water before it is sent to the steam pipe.
• Q4: What is a Super Heater?
  Ans: A super heater is a device used in a boiler to increase the temperature of steam above its boiling point. It converts wet steam into dry and superheated steam, which increases efficiency and prevents damage to machinery.
• Q5: Define Economiser.
  Ans: An economiser is a device used in boilers to heat the feed water before it enters the boiler. It uses the waste heat from flue gases to save fuel and improve efficiency.
• Q6: Define Air Pre Heater.
  Ans: An air pre heater is a device that heats the air before it enters the furnace. It uses the heat of exhaust gases, which improves combustion and saves fuel.
• Q7: Define Reheater.
  Ans: A reheater is a device used in power plants to reheat steam after it has passed through a turbine. Reheating increases efficiency and reduces moisture content in steam.
• Q8: State the classification of Boilers.
  Ans: The classification of Boilers is as follows:

  • ➔ According to the Contents in the Tube
    • ➔ Water Tube Boiler
    • ➔ Fire Tube Boiler
  • ➔ According to the Position of Furnace
    • ➔ Internally Fired Boiler
    • ➔ Externally Fired Boiler
  • ➔ According to the Axis of the Shell
    • ➔ Vertical Boiler
    • ➔ Horizontal Boiler
  • ➔ According to the Number of Tubes
    • ➔ Single Tube Boiler
    • ➔ Multi Tube Boiler
  • ➔ According to Use
    • ➔ Mobile Boilers
    • ➔ Stationary Boiler
  • ➔ According to the Circulation method of Water and Steam
    • ➔ Natural Circulation Boiler
    • ➔ Forced Circulation Boiler
• Q9: What are some selection factors of a good steam boiler?
  Ans: The selection factors of a good steam boiler are:

  • ➔ Required steam pressure and temperature
  • ➔ Steam generation capacity
  • ➔ Fuel type and availability
  • ➔ Efficiency of the boiler
  • ➔ Initial and maintenance cost
  • ➔ Safety and reliability
• Q10: Define Vertical Boiler.
  Ans: A vertical boiler is a boiler in which the axis of the shell is vertical. It occupies less floor space and is suitable for small industries.
• Q11: Name some Vertical Boilers.
  Ans: Some vertical boilers are:

  • ➔ Simple Vertical Boiler
  • ➔ Cochran Boiler
• Q12: Define Horizontal Boiler.
  Ans: A horizontal boiler is a boiler in which the axis of the shell is horizontal. It is commonly used in large industries and power plants.
• Q13: Name some Horizontal Boilers.
  Ans: Some horizontal boilers are:

  • ➔ Lancashire Boiler
  • ➔ Locomotive Boiler
  • ➔ Babcock and Wilcox Boiler
• Q14: Define Mobile Boiler.
  Ans: A mobile boiler is a boiler that can move from one place to another. It is mainly used in locomotives and ships.
• Q15: Name some Mobile Boilers.
  Ans: Some mobile boilers are:

  • ➔ Locomotive Boiler
  • ➔ Marine Boiler
• Q16: Define Stationary Boiler.
  Ans: A stationary boiler is a boiler that is fixed at one place and cannot be moved. It is mainly used in power plants and industries.
• Q17: Name some Stationary Boilers.
  Ans: Some stationary boilers are:

  • ➔ Lancashire Boiler
  • ➔ Babcock and Wilcox Boiler
  • ➔ Cochran Boiler
• Q18: Define Single Tube Boiler.
  Ans: A single tube boiler is a boiler that has only one fire tube or water tube. It has a simple design and is used for small capacity.
• Q19: Name some Single Tube Boilers.
  Ans: Some single tube boilers are:

  • ➔ Cornish Boiler
  • ➔ Simple Vertical Boiler
• Q20: Define Multi Tube Boiler.
  Ans: A multi tube boiler is a boiler that has many fire tubes or water tubes. It produces more steam and has higher efficiency than single tube boilers.
• Q21: Name some Multi Tube Boilers.
  Ans: Some multi tube boilers are:

  • ➔ Lancashire Boiler
  • ➔ Locomotive Boiler
  • ➔ Babcock and Wilcox Boiler
• Q22: Define Natural Circulation Boiler.
  Ans: A natural circulation boiler is a boiler in which water circulates naturally due to the difference in density between hot and cold water. No external pump is required.
• Q23: Define Forced Circulation Boiler.
  Ans: A forced circulation boiler is a boiler in which water is circulated with the help of a pump. It allows better control and is used in high-pressure boilers.
• Q24: Name some Natural Circulation Boilers.
  Ans: Some natural circulation boilers are:

  • ➔ Lancashire Boiler
  • ➔ Cochran Boiler
  • ➔ Babcock and Wilcox Boiler
• Q25: Name some Forced Circulation Boilers.
  Ans: Some forced circulation boilers are:

  • ➔ LaMont Boiler
  • ➔ Benson Boiler
  • ➔ Loeffler Boiler
• Q26: Define Water Tube Boiler.
  Ans: A water tube boiler is a boiler in which water flows inside the tubes and hot gases flow outside the tubes. It is suitable for high-pressure steam generation.
• Q27: Name some Water Tube Boilers.
  Ans: Some water tube boilers are:

  • ➔ Babcock and Wilcox Boiler
  • ➔ LaMont Boiler
  • ➔ Benson Boiler
• Q28: Define Smoke or Fire Tube Boiler.
  Ans: A fire tube boiler is a boiler in which hot gases pass through the tubes and water surrounds the tubes. It is suitable for low-pressure steam generation.
• Q29: Name some Fire Tube Boilers.
  Ans: Some fire tube boilers are:

  • ➔ Lancashire Boiler
  • ➔ Cochran Boiler
  • ➔ Cornish Boiler
  • ➔ Locomotive Boiler
• Q30: Name some fuels used as a heat source in a boiler.
  Ans: Some fuels used in boilers are:

  • ➔ Coal
  • ➔ Diesel
  • ➔ Furnace Oil
  • ➔ Natural Gas
  • ➔ Biomass
• Q31: What is a Boiler Shell?
  Ans: A boiler shell is the outer cylindrical body of the boiler. It is made of strong steel plates and holds water and steam inside it. The shell must be strong enough to withstand high pressure and temperature.
• Q32: What is a Combustion Chamber?
  Ans: A combustion chamber is the space inside the boiler where fuel is burnt. In this chamber, fuel mixes with air and produces heat energy, which is used to convert water into steam.
• Q33: Define Grate.
  Ans: A grate is a metal platform with small openings placed inside the furnace. Solid fuel like coal is placed on it for burning. The openings allow air to pass for proper combustion and let ash fall down.
• Q34: Define Furnace.
  Ans: A furnace is the part of a boiler where fuel is burnt to produce heat. The heat generated in the furnace is used to convert water into steam.
• Q35: Define Mountings.
  Ans: Mountings are safety devices fitted on the boiler for its safe operation. They control pressure, water level, and steam flow, and prevent accidents.
• Q36: Define Firebox.
  Ans: A firebox is a chamber where fuel is burnt in certain types of boilers like locomotive boilers. It is surrounded by water so that the heat produced is directly transferred to water.
• Q37: Briefly explain the working of a Simple Vertical Boiler.
  Ans: In a simple vertical boiler, fuel is burnt in the furnace. The hot gases rise upward through the fire tubes and heat the water surrounding them. Water gets converted into steam and collects at the top (steam space). The steam is then taken out through the steam outlet valve for use.
• Q38: What is a Cochran Boiler?
  Ans: A Cochran boiler is a vertical, multi-tube, fire tube boiler. It is commonly used in small industries for low-pressure steam generation.
• Q39: Briefly explain the working of a Cochran Boiler.
  Ans: In a Cochran boiler, fuel is burnt in the furnace. Hot gases pass through fire tubes surrounded by water. Heat is transferred to water and steam is produced. The steam collects in the steam space and is taken out through the steam stop valve.
• Q40: What is a Marine Boiler?
  Ans: A marine boiler is a boiler used in ships to produce steam. It is generally a fire tube boiler and is designed to work safely under sea conditions.
• Q41: Briefly explain the working of a Marine Boiler.
  Ans: In a marine boiler, fuel burns in the furnace and produces hot gases. These gases pass through tubes surrounded by water. Water absorbs heat and converts into steam, which is used to run ship engines.
• Q42: What is a Locomotive Boiler?
  Ans: A locomotive boiler is a horizontal, multi-tube, fire tube boiler used in railway engines. It produces steam to run the locomotive.
• Q43: Briefly explain the working of a Locomotive Boiler.
  Ans: In a locomotive boiler, coal is burnt in the firebox. Hot gases pass through many small fire tubes. Water around these tubes gets heated and turns into steam. The steam is supplied to the engine to move the train.
• Q44: What is a Babcock and Wilcox Boiler?
  Ans: A Babcock and Wilcox boiler is a horizontal, water tube boiler used for high-pressure steam generation. It is widely used in power plants.
• Q45: Briefly explain the working of a Babcock and Wilcox Boiler.
  Ans: In this boiler, water flows inside inclined tubes and hot gases pass outside the tubes. The heat converts water into steam. Steam rises to the steam drum and is collected for use.
• Q46: What is Boiler Mountings?
  Ans: Boiler mountings are essential safety fittings provided on the boiler to ensure safe and smooth operation. They include pressure gauge, safety valve, water level indicator, and others.
• Q47: What is the use of Pressure Gauge?
  Ans: A pressure gauge is used to measure and show the steam pressure inside the boiler. It helps the operator to maintain safe working pressure.
• Q48: What is the use of a Water Level Indicator?
  Ans: A water level indicator shows the level of water inside the boiler. It ensures that the boiler does not run dry, which could cause damage or explosion.
• Q49: What is the use of Safety Valves?
  Ans: Safety valves release excess steam automatically when the pressure exceeds the safe limit. They prevent explosion and protect the boiler.
• Q50: What is a Blow off Cock?
  Ans: A blow off cock is a valve fitted at the bottom of the boiler. It is used to remove mud, scale, and sediments from the boiler.
• Q51: What is Feed Check Valve?
  Ans: A feed check valve controls the supply of water into the boiler. It prevents backflow of water from the boiler.
• Q52: What is the use of Fusible Plug?
  Ans: A fusible plug is a safety device fitted in the furnace. It melts when the water level falls below a safe limit, preventing overheating and explosion.
• Q53: Name some accessories of a Boiler.
  Ans: Some boiler accessories are:

  • ➔ Economiser
  • ➔ Super Heater
  • ➔ Air Pre Heater
  • ➔ Feed Pump
• Q54: What is Equivalent Evaporation of a Boiler?
  Ans: Equivalent evaporation is the amount of water evaporated into dry steam from water at 100°C. It is used to compare boiler performance.
  Formula:
  Equivalent Evaporation = (m × (h₂ — h₁)) / 2257
• Q55: What is the Efficiency of a Boiler?
  Ans: Boiler efficiency is the ratio of heat utilized in producing steam to the total heat supplied by fuel.
  Formula:
  Efficiency = (Heat used to produce steam / Heat supplied by fuel) × 100%
• Q56: What is the horsepower of a boiler?
  Ans: Boiler horsepower is a unit to measure boiler capacity. One boiler horsepower is equal to the evaporation of 34.5 lb of water per hour from and at 100°C.
• Q57: State two advantages of air preheater.
  Ans: Advantages of air preheater:

  • ➔ Increases boiler efficiency
  • ➔ Saves fuel by improving combustion
• Q58: State some safety valves used in Boilers.
  Ans: Some safety valves used in boilers are:

  • ➔ Lever Safety Valve
  • ➔ Dead Weight Safety Valve
  • ➔ Spring Loaded Safety Valve
• Q59: What is a Feed Pump?
  Ans: A feed pump is a pump used in a boiler system to supply water into the boiler. It forces water into the boiler at high pressure so that steam can be produced continuously.
• Q60: What is a Super Heater?
  Ans: A super heater is a device used in a boiler to increase the temperature of steam above its boiling point. It converts saturated steam into superheated steam, which improves the efficiency of the steam turbine.
• Q61: Compare Water Tube and Fire Tube Boiler.
  Ans:

  Aspects	Water Tube Boiler	Fire Tube Boiler
  Flow of Water and Gas	Water flows inside the tubes, hot gases flow outside	Hot gases flow inside the tubes, water surrounds them
  Pressure	Suitable for high pressure	Suitable for low pressure
  Efficiency	Higher efficiency	Lower efficiency
  Construction	Complex construction	Simple construction
  Steam Generation	Faster steam generation	Slower steam generation