Boiler auxiliaries — identify the function: Does a superheater heat the feedwater using exhaust flue gases before the gases leave through the chimney?

Introduction:
Three common heat-recovery devices surround boilers: economisers, air preheaters, and superheaters. Each acts on a different working medium. Confusing their roles leads to design and operational errors.

Given Data / Assumptions:

• Conventional steam generator with flue-gas path.
• Presence of feedwater circuit and superheater bank.

Concept / Approach:
A superheater increases the temperature of steam above saturation at boiler pressure. An economiser heats feedwater using flue-gas waste heat. An air preheater warms combustion air before the furnace. Therefore, the statement that a superheater heats feedwater is incorrect; that duty belongs to the economiser.

Step-by-Step Solution:

Verification / Alternative check:
Boiler heat balance diagrams locate the superheater downstream of the evaporator, acting on steam, while the economiser precedes the drum, acting on feedwater. This confirms the functional distinction.

Why Other Options Are Wrong:

• Any “Yes” variant: misidentifies the device. The correct device for feedwater is the economiser.
• “Only in economiser sections”: acknowledges the right device but the statement still mislabels the superheater.

Common Pitfalls:
Assuming all flue-gas heat exchangers are interchangeable; misplacing components in the gas path.

Final Answer: