Question

Which of the given boilers operate above critical pressure?

(a) Natural circulation boilers

(b) Forced circulation boilers

(c) Once-through boilers

(d) Water tube boilers

I got this question during an internship interview.

I'd like to ask this question from Boiler Classification topic in section Steam Generators & Accessories of Energy Engineering

Answer 1

Right answer is (c) Once-through boilers

Explanation: Once-through boilers operate above critical pressure i.e., above 221.2bar. As the density of water and steam are same above the critical pressure there will be no recirculation. These types of boilers are also called as positive forced circulation boilers.