Industrial applications of fireclay bricks: identify where fireclay bricks are generally <em>not</em> used due to service temperature and chemical demands.

Introduction:
Fireclay refractories (alumino-silicate) are widely used below ultra-high temperatures, whereas silica refractories dominate extremely hot zones like coke oven crowns and regenerators. Choosing the wrong brick can cause rapid creep, deformation, or chemical attack.

Given Data / Assumptions:

• Fireclay bricks have moderate refractoriness and good thermal-shock resistance.
• Coke oven regenerators experience very high steady temperatures and thermal cycling.
• Other listed units may run at temperatures compatible with fireclay in selected zones.

Concept / Approach:
Silica refractories excel at very high temperatures and resist creep, making them standard for coke oven chambers and regenerators. Fireclay is common in lower-temperature zones, backup linings, or where thermal shock is frequent but peak temperatures are lower.

Step-by-Step Solution:
List typical service temperatures: coke oven regenerators approach high steady temperatures favoring silica bricks.Assess each candidate unit’s lining practice: the regenerator’s hot-end design relies on silica’s stability.Conclude that fireclay is generally not used in the coke oven regenerators.

Verification / Alternative check:
Standard refractory selection guides recommend silica for coke oven walls and regenerators because of dimensional stability at high temperature and resistance to creep.

Why Other Options Are Wrong:

• Beehive coke oven and some stove chambers can employ fireclay in certain zones at lower peak temperatures.
• The combustion chamber of BF stoves may incorporate fireclay in selected sections depending on duty.
• General furnace crowns vary; many hot crowns use silica but not exclusively; question targets the unit most clearly ill-suited to fireclay: the coke oven regenerator.

Common Pitfalls:
Assuming one refractory type fits all zones; actual practice uses graded linings with silica in the hottest areas and fireclay below.

Final Answer:
Coke oven regenerators