Heat recovery hardware in furnaces/boilers: Which statement best describes a recuperator used for waste-heat recovery from hot flue gases?

Introduction / Context:
High-temperature furnaces and boilers improve efficiency by reclaiming sensible heat from outgoing flue gases. Two broad families exist: recuperators and regenerators. Knowing the operating mode of each helps with correct specification and troubleshooting of efficiency shortfalls.

Given Data / Assumptions:

• Hot flue gases are available from a process heater or furnace.
• Goal is preheating combustion air or another stream to cut fuel consumption.
• “Continuous” means heat is transferred without periodic flow reversal or storage cycles.

Concept / Approach:
A recuperator is a steady-flow heat exchanger (metallic or ceramic) that continuously transfers heat from hot flue gas to a cold stream (often combustion air). No checker-brick storage is involved. In contrast, a regenerator alternately stores heat in a thermal mass and then releases it after flow reversal, a cyclic process.

Step-by-Step Solution:
Identify the device that does not rely on cyclic storage: the recuperator.Recognize its function: continuous sensible-heat transfer across a barrier.Therefore, the correct description is “A continuous waste-heat recovery equipment”.

Verification / Alternative check:
Vendor datasheets classify recuperators under continuous service, while regenerators are documented with flow-reversal cycles and checkerwork descriptions.

Why Other Options Are Wrong:
Not used for fuel gas preheating: incorrect; recuperators frequently preheat combustion air and sometimes gaseous fuels where appropriate.Intermittent: that is the regenerator, not the recuperator.Heavier than a regenerator: generally the opposite for the same duty; regenerators are typically bulkier.Stores heat cyclically: definition of a regenerator, not a recuperator.

Common Pitfalls:
Confusing “recuperator” and “regenerator” because both reduce fuel use. The key distinction is continuous vs. cyclic operation.

Final Answer:
A continuous waste-heat recovery equipment