Identify the unit that is <em>not</em> a recuperative furnace (i.e., it does not primarily rely on a continuous recuperator for air-preheating heat recovery).

Introduction / Context:
Heat recovery devices are broadly of two types: regenerators (cyclic storage and release of heat) and recuperators (continuous heat exchange across a wall). Many furnaces can be classed by which they use, and the terminology often appears in exam questions. Here we must identify which listed unit is not principally recuperative.

Given Data / Assumptions:

• Soaking pits and reheating furnaces commonly use recuperators or recuperative burners.
• Steam boilers are not classed as “recuperative furnaces” per se; they are steam generators but may have economizers/air preheaters as heat exchangers.
• Coke ovens (by-product type) employ classic regenerators with checker-brick chambers and periodic reversal.

Concept / Approach:
A recuperator transfers heat continuously from hot flue gas to cold air through a wall. A regenerator alternates the flow, storing heat in solids and then giving it back. By-product coke ovens have regenerator chambers integral to their design; therefore, they are not “recuperative furnaces.” Soaking pits and reheating furnaces frequently feature recuperation (or recuperative burners) for continuous preheating.

Step-by-Step Solution:
Classify each item by typical heat-recovery method.Coke oven → regenerative; soaking pit and reheating furnace → often recuperative.Select the unit that is not recuperative: coke oven.

Verification / Alternative check:
Process descriptions of by-product coke ovens highlight periodic flow reversal through checkerwork, the hallmark of regeneration, not recuperation.

Why Other Options Are Wrong:
Soaking pit / Reheating furnace: Commonly paired with recuperators for air preheat.Steam boiler: While not a “furnace type,” this option does not better fit the “not recuperative” label than the clearly regenerative coke oven.

Common Pitfalls:

• Confusing boilers with furnaces; the question targets furnace heat-recovery classification.
• Assuming all high-temperature units use the same recovery method.

Final Answer:
Coke oven.