Tunnel Kiln Car Thermal Management FAQ (Frequently Asked Questions)

Q1: Why is the kiln car considered the key weakness in tunnel kiln operation?
A: The kiln car in a tunnel kiln not only supports and transports green bricks but also directly participates in heat exchange. Its heat storage and thermal loss are significant, accounting for 30%–50% of the kiln's total energy consumption. Poor design can severely reduce kiln efficiency, increase operating costs, and raise maintenance burdens.

Q2: What are the main functions of the kiln car during operation?
A: The two core functions of the kiln car are:
(1) Product support: Withstands the weight of green bricks and mechanical loads under high temperatures.
(2) Thermal insulation: Prevents high-temperature heat from transferring to the kiln’s base structure and external environment, reducing heat loss.

Q3: Why do the kiln car’s support and insulation functions often conflict?
A: Because:
(1) Load-bearing materials (such as high-alumina bricks, silicon carbide) have high density but poor insulation.
(2) High-efficiency insulation materials (such as ceramic fiber, foam bricks) have low strength and cannot bear heavy loads.
(3) This forces a trade-off between insulation and mechanical strength in design.

Q4: What are the specific sources of energy waste caused by the kiln car?
Heat Loss Source                                         Estimated Share
Downward heat conduction to kiln base        10–15%
Kiln car heat storage + cooling loss               10–20%
Cooling air leakage disrupting atmosphere    5–10%
Total                                                                Up to ~50%

Q5: How can the kiln car structure be optimized to reduce energy consumption?
A:
(1) Multi-layer lining design (upper load-bearing layer + middle lightweight insulation + lower thermal blanket).
(2) Keep the total car weight below 1.5 times the green brick load.
(3) Control heat loss rate below 600–800 W/m².

Q6: How can the kiln car’s cooling system be improved to reduce air leakage and thermal shock?
A:
(1) Enhance sealed air ducting to focus cooling on bearings and chassis.
(2) Install return air channels to recover waste heat from cooling air.
(3) Add thermal isolation skirts at the car bottom to prevent air short-circuiting.

Q7: What are the common issues with sand seal systems, and how can they be improved?
A: Common issues:
(1) Poor sealing leading to air leakage.
(2) Seal material degradation under high temperatures.
(3) Increased resistance due to insufficient cleaning.
Improvement measures:
(1) Use ceramic sand or anti-sintering silica sand.
(2) Upgrade to "floating seal structures" or metal skirt seals.
(3) Install automatic sand replenishment and monitoring systems.

Q8: What are the consequences of not optimizing the kiln car’s thermal performance?
A:
(1) 15–20% increase in energy consumption per brick.
(2) Longer kiln heating time, slower cycle efficiency.
(3) Increased thermal stress, leading to car body deformation, track damage, and higher maintenance costs.
(4) Unstable kiln atmosphere, causing inconsistent brick quality and higher defect rates.

Q9: What are the key benefits after optimizing kiln car thermal management?
A:
(1) Energy savings of 15–20%.
(2) Improved product consistency and firing quality.
(3) Extended kiln car lifespan, reduced maintenance frequency.
(4) Optimized auxiliary system loads (fans, burners) and configurations.
(5) Enhanced EPC project economics and environmental compliance.

Author: JF&Lou