Industrial furnaces—zone design and function Which furnace type is specifically designed with three distinct regions—preheating, main heating, and soaking zones—for uniform reheating of metal stock prior to hot-working?

Introduction / Context:
Modern steelworks and forging shops require controlled temperature profiles before rolling or shaping. Industrial furnaces are therefore built with functional zones to raise, equalize, and homogenize temperature. Understanding which furnace employs preheating, heating, and soaking zones is central to thermal processing and product quality.

Given Data / Assumptions:

• The question concerns common metallurgical furnaces used for ingots, slabs, billets, and blooms.
• Zone names: preheating (recovering heat from flue gases), main heating (rapid heat input), and soaking (equalization at setpoint).
• Focus is on typical industrial practice rather than niche designs.

Concept / Approach:
Reheating furnaces (walking beam, pusher, or walking hearth) are purpose-built with three zones. Stock enters the preheating zone, passes to the higher-temperature heating zone, and then resides in the soaking zone to even out core-surface temperatures before hot working. Soaking pits, open-hearth furnaces, and cupolas have different primary purposes or configurations.

Step-by-Step Solution:

Verification / Alternative check:
Process flow diagrams of walking-beam furnaces show counter-current flue gas flow in preheat and high firing in the heating zone, followed by a soak region near the discharge end.

Why Other Options Are Wrong:

• Soaking pit: primarily a soaking chamber without staged preheat and reheat zones.
• Open-hearth furnace: historical steelmaking furnace, not a reheater.
• Cupola: vertical shaft melting furnace for cast iron; no soak zone arrangement as described.

Common Pitfalls:
Equating 'soaking' in a pit with the three-zone layout. Soaking pits operate at near-uniform temperature, lacking the distinct preheat/heating stages of reheaters.

Final Answer:
Reheating furnace