Boiler Accessories — Identification and Function In steam power-plant practice, which of the following items are classified as boiler accessories (i.e., performance-enhancing external devices, not mandatory safety mountings)?

Introduction / Context:
Boiler hardware is grouped into mountings and accessories. Mountings are essential safety and control fittings fixed on the pressure shell, while accessories are external devices that improve efficiency and output. This question checks whether you can correctly recognise typical accessories used on industrial boilers.

Given Data / Assumptions:

• An economiser recovers heat from hot flue gases to preheat feedwater.
• A superheater raises steam temperature above saturation at the working pressure.
• Classification is per standard power-plant engineering terminology.

Concept / Approach:
Accessories increase plant efficiency or capacity but are not strictly mandatory for safe boiler operation. An economiser reduces stack losses by increasing feedwater enthalpy before it enters the boiler drum or steam generator. A superheater increases the specific enthalpy of steam, improves cycle efficiency, reduces turbine moisture, and increases work potential. Both are, therefore, classic examples of accessories, contrasted with mountings such as safety valves, water level gauges, and blow-off cocks that are essential for safe operation.

Step-by-Step Solution:
List typical accessories: economiser, superheater, air preheater, steam injector, etc.Identify their role: recover waste heat or enhance steam quality; not basic safety devices.Compare with mountings: safety valve, pressure gauge, water level indicator, feed check valve, fusible plug, stop valve, blow-off cock.Conclude that both economiser and superheater are accessories.

Verification / Alternative check:
Boiler codes and textbooks list economisers and superheaters under accessories, distinct from mandatory mountings.

Why Other Options Are Wrong:
economiser: correct but incomplete because superheater is also an accessory.superheater: correct but incomplete for the same reason.none of these: incorrect; both listed items are accessories.

Common Pitfalls:
Confusing accessories with mountings; remember that mountings are safety-critical and fixed to the shell.

Final Answer:
both (a) and (b)