This set of Thermal Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Steam Generators – Classification of Boilers”.
1. Which of the following is NOT a fire tube boiler?
a) Cochran Boiler
b) Lancashire Boiler
c) Locomotive Boiler
d) Babcock and Wilcox Boiler
Explanation: In case of fire tube boilers, hot gases flow through tubes and water surrounds the tubes and in case of water tube boilers, water flows through the tubes and hot gases surround the tubes. Cochran, Lancashire, Locomotive are all fire tube boilers while Babcock and Wilcox is a water tube boiler.
2. Which of the following is NOT a valid classification of boilers?
a) Forced circulation and natural circulation
b) High pressure and low pressure
c) Stationary and Portable
d) Single fired and Double fired
Explanation: Boilers are classified into internally fired and externally fired on the basis of firing. There is no such classification as single fired and double fired.
3. Babcock and Wilcox boiler is an internally fired boiler.
Explanation: In case of internally fired boiler furnace is located inside the boiler, while in externally fired boilers furnace is outside the boiler. Babcock and Wilcox boiler has its furnace outside, hence it’s a externally fired boiler.
4. Which of the following statement is NOT true about fire tube boilers?
a) Hot gases are inside the tubes and water surrounds them
b) For a given power it occupies more floor area
c) Operating pressure can be as high as 100 bars
d) Not suitable for large power plants
Explanation: The operating pressure for fire tube boilers is limited to 16 bars. For a given power it occupies more floor area, hence it is not suitable for large power plants.
5. The classification of boilers into horizontal, vertical and inclined is done on the basis of their _____
b) method of firing
Explanation: Boilers are classified as high and low pressure boilers on the basis of pressure, internally fired and externally fired on the basis of method of firing, water tube and fire tube on the basis of relative position of hot gases and water and as horizontal, vertical and inclined on the basis of their axis.
6. Which of the following is a low pressure boiler?
a) Babcock and Wilcox boiler
b) Benson boiler
d) Lamont Boiler
Explanation: Boilers with production of steam below 80 bar of pressure are call low pressure boilers. Lancashire boiler is a low pressure boiler while the rest of given options are high pressure boilers.
7. Which of the following statement is FALSE about boilers?
a) Portable boilers are also called as mobile boilers
b) Lamont boiler is a forced circulation type boiler
c) Cochran boiler is a high pressure boiler
d) Horizontal boilers occupy more space
Explanation: Cochran boiler produces steam at a pressure greater than 80 bar, hence it’s a high pressure boiler. A pump is used to circulate water in Lamont boiler, therefore it is classified as forced circulation boiler. Portable boilers are also called as mobile boilers; they include locomotive type boilers. Horizontal boilers occupy more space but can be easily repaired and inspected.
8. Which of the following statement is TRUE about fire tube and water tube boilers?
a) Fire tube boilers have high risk of bursting than water tube boilers
b) Water tube boilers have high risk of bursting than fire tube boilers
c) Bursting of boilers isn’t possible
d) It depends upon the quality of water fed to the boiler
Explanation: Operating pressure of water tube boilers can be as high as 100 bar whereas for fire tube boilers the operating pressure is limited to 16 bar. Therefore, water tube boilers have high risk of bursting.
9. Which of the following is NOT a forced circulation boiler?
a) Velox boiler
b) Lancashire boiler
c) Lamont boiler
d) Benson boiler
Explanation: Circulation of water is done by use of pumps in case of forced circulation boilers. In case of Lancashire boiler, the circulation of water takes place due to natural convection current, therefore it a natural circulation boiler and not a forced circulation one.
10. Which of the following is NOT true about Babcock and Wilcox boiler?
a) Water tube boiler
b) Externally fired
c) High pressure boiler
d) Single tube
Explanation: Babcock and Wilcox is an externally fired, high pressure and water tube boiler. It is also a multi-tube boiler since it has multiple tubes for the flow of water.
11. Which of the following is a single tube boiler?
a) Cornish boiler
b) Lancashire boiler
c) Benson boiler
d) Cochran boiler
Explanation: In case of single tube boilers, there is only one tube through which hot gases or water passes. Cochran boiler is an example of single tube boiler. In multi-tube boiler there are multiple tubes for passing of water (or hot gases). Lancashire boiler, Benson boiler and Cornish boiler are all examples of multi-tube boilers.
12. In natural circulation boilers, water circulation takes place due to natural convection current produced by the application of heat.
Explanation: The given statement is the definition of natural circulation boilers. Lancashire and Babcock and Wilcox boiler are examples of natural circulation boilers.
13. Stationary boilers are used for _____
a) locomotive applications
b) temporary applications
c) power plant steam generation
d) marine application
Explanation: Stationary boilers are used for power plant steam generation. Mobile or portable boilers are used for marine and locomotive applications. For temporary use like in small coal field pits involves use of portable boilers.
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