Steam, Feedwater and Auxiliary Systems
Steam systems
Understand the properties of saturated and superheated steam, and the meaning of dryness fraction. Know how steam traps work (thermodynamic, thermostatic, float) and why they are needed to remove condensate and air. Understand the steam distribution system, insulation, drain points and the danger of water hammer from accumulated condensate. Know the function of the superheater and why attemperation is used.
Feedwater systems
Know the feedwater path: storage, treatment, deaerator, feed pump, economiser, boiler. Understand the feed pump types (centrifugal, reciprocating), the purpose of the feed check valve and the feed regulator. Know why the feedwater temperature matters to efficiency and to thermal stress, and how the economiser recovers heat.
Auxiliary systems
Recognise the air and flue gas path, forced and induced draught fans, air heaters, sootblowers and the stack. Understand the function of the deaerator and the feedwater heater.
Traps
Questions often confuse a steam trap with a valve, or ask what causes water hammer. Another trap is the economiser: it heats feedwater, not air. Do not assume superheated steam is always hotter than saturated steam at the same pressure; it is, but the key point is that it has no moisture.
Worked example
If a superheater outlet temperature rises above design, reason that attemperation water should be increased or excess air reduced, and check for a stuck control valve before assuming a tube failure.
Rule of thumb
Remove condensate and air continuously; keep feedwater hot and treated.