Waste-heat boiler design for furnace gas recovery In industrial furnace technology, the design of a waste-heat boiler used to recover heat from furnace exhaust gases primarily depends on which set of gas characteristics?

Introduction / Context:
Waste-heat boilers (WHBs) recover sensible heat from hot furnace off-gases and convert it to useful steam or hot water. Proper design must consider several gas-side parameters to ensure high efficiency, reliability, and safe operation in real plant conditions.

Given Data / Assumptions:

• The WHB serves a furnace exhaust stream.
• We compare the importance of gas quantity and temperature, dust loading and dust character, and corrosivity.
• Only one option should best capture the full design dependency.

Concept / Approach:
Gas-side design governs heat-transfer area, tube geometry, fouling allowances, cleaning provisions, metallurgy, and allowable gas velocities. These choices hinge on thermal load (flow and temperature), particulate nature (erosion, deposition, and plugging risks), and chemistry (acid dew points and high-temperature corrosion).

Step-by-Step Solution:

Verification / Alternative check:
Field practice shows WHBs frequently fail due to fouling/erosion (dust) or cold-end corrosion (chemistry) rather than pure thermal sizing, confirming that multi-parameter design is essential.

Why Other Options Are Wrong:

Common Pitfalls:
Designing solely on thermal load, underestimating dust stickiness, and setting gas exit temperature below acid dew point causing rapid corrosion.

Final Answer:
all (a), (b) and (c).