Quality Management and System Coordination in Tunnel Kiln Construction

1. Introduction：
Tunnel kilns are the core thermal equipment in modern clay brick production. Their construction process directly impacts structural stability, thermal efficiency, and product quality. However, some construction teams treat tunnel kilns as conventional civil structures, overlooking their nature as thermal systems. This misperception leads to frequent quality issues. This paper outlines five dimensions of quality control in tunnel kiln construction: structural engineering, material selection, thermal logic, equipment compatibility, and construction technology.

2. Tunnel Kiln is a Thermal System, Not a Simple Building:
Tunnel kilns differ from conventional buildings as they operate under sustained high-temperature conditions. They combine structural, thermal, and process systems:
(1) Foundation design must accommodate thermal stress, equipment load, and expansion/contraction effects;
(2) Structural components like rails, beams, and hangers experience alternating thermal stress and require higher-grade materials;
(3) The kiln’s thermal system includes burner arrangement, sealing, fans, gas circulation, and heat insulation, all forming a cross-disciplinary engineering system.

3. Key Problems and Solutions During Construction:
(1). Foundation Settling and Cracking
Cause: Foundation designed with reference to civil buildings without considering thermal operations.
Solution:
Differentiate between structural settlement joints and thermal expansion joints;
Avoid limestone aggregate; use medium-grade cement and ductile steel;
(2). Rail Deformation and Fracture
Problems: Rail elongation, derailment, beam cracks, or use of iron instead of steel rails.
Solution:
Use high-manganese or alloy steel rails with proper expansion gaps and anchors;
Prohibit iron rails, inspect beam concrete strength before installation;
(3). Kiln Wall Cracks and Roof Collapse
Cause: Inappropriate refractory materials, poor drying protocol, or weak anchoring systems.
Solution:
Match refractory material grades to each thermal zone (high-temp, insulation, etc.);
Enforce third-party material testing and execute controlled kiln drying curves;

(4). Seal Sand Loss and Poor Sealing
Problems: Sand leaks into track area, impeding cart movement.
Solution:
Use heat-resistant sealing channels with wear-resistant materials;
Implement regular inspection and replacement schedules;
(5). Hanger System and Fastener Failure
Problems: Column deformation, beam sagging, bolt loosening.
Solution:
Use “positive tolerance” steel, never inferior substitutes;
Load-test beams post-installation and inspect regularly for fatigue;
(6). Corrosion of Fans and Ducts
Problem: Fans/ducts fail prematurely in coal gangue or fly ash kilns.
Solution:
Pre-analyze sulfur content in raw materials;
Use acid-resistant alloys, anti-corrosion coatings, and vibration dampeners;
Redesign flue systems for high-sulfur fuels to segment hot air flows.

4. System-Level Integration is Essential
Tunnel kilns are not simply a combination of devices but integrated systems involving process control, thermal engineering, structure, and automation. Common mistakes include:
(1) Focusing only on masonry and ignoring thermal/process coordination;
(2) Equating equipment quality with kiln quality while neglecting design and fuel adaptation;
(3) Allowing equipment suppliers to lead construction without thermal engineering input.

5. Conclusion
The tunnel kiln is a complex thermal-process structure. Construction quality must not focus solely on materials or assembly, but on system-level coordination. Every component, device selection, and setting must serve the goal of efficient, safe, and long-life operation. Only through this perspective can a high-performance tunnel kiln be realized.