Question

In a fire tube boiler, the operating pressure range is:
1. 30 to 35 bar
2. 26 to 29 bar
3. 21 to 25 bar 
4. 16 to 20 bar

Answer 1

Correct Answer - Option 4 : 16 to 20 bar

Explanation:

Fire Tube boiler:

• In this boiler, the hot flue gases are present inside the tubes and water surrounds them and sometimes around the outside of the tubes.
• Hence we can say that they are internally as well as externally fired boilers.
• They are low-pressure boilers. The operating pressure is about 15 to 20 bar.
• Externally fired fire tube boilers are locomotive type boilers, horizontal return tubular (HRT) boiler, etc.
• Internally fired fire tube boilers are Scotch-marine boilers, Cochran boiler, package boilers, etc. 

Water Tube Boiler:

• In this boiler, the water is present inside the tubes and the hot flue gases surround them.
• They are high-pressure boilers and the operating pressure is about 250 bar.
• Water-tube boilers are always externally fired.
• Stirling Boiler, La-Mont Boiler, Benson Boiler, Yarrow Boiler, Babcock and Wilcox Boilers are water tube boilers.