Question

Operating pressure for the once-through boiler is:

1. subcritical
2. subcritical and critical
3. critical
4. super-critical

Answer 1

Correct Answer - Option 4 : super-critical

Explanation:

Supercritical boiler:

• A large number of steam generating units are designed between working ranges of 125 atm and 510°C to 300 atm and 660°C. These are basically characterised as subcritical and supercritical. Subcritical consists, preheater, evaporator and superheater while supercritical boiler requires only preheater and superheater.
• Supercritical boilers operate at a pressure greater than 22 MPa and also referred to as Once through boilers since the feed water circulates only once through boiler in each steam cycle.