Tunnel Kiln Car Optimization: Enhance Refractory Performance, Service Life and Thermal Sealing for Fired Bricks
Tunnel kilns are core thermal equipment for fired brick and ceramic product firing processes. The kiln car frame and sand sealing plate are key components made of cast iron or steel plates, continuously exposed to high-temperature atmosphere inside the kiln. Without sufficient resistance to thermal expansion deformation and thermal oxidation corrosion, the thermal sealing capacity of the kiln car will rapidly degrade over operating cycles.
Low-performance kiln cars bring multiple production risks. The frame cannot hold groove bricks steadily. Vibration and shaking during movement disrupt the firing environment. This results in brick shape distortion and cold cracking, downgrading finished brick quality. Once this issue appears, on-site maintenance cannot be performed immediately. Operators have to keep the kiln running until scheduled or emergency shutdown. In worst scenarios, groove bricks lose support balance, the whole kiln car frame collapses, damaging the main kiln body, kiln bed, wheels and rail system.
Degraded thermal sealing of sand sealing plates allows hot kiln gas to leak through gaps between the kiln wall and kiln car side panels into the undercarriage space. Uneven temperature distribution emerges across the firing chamber. The firing degree of bricks becomes inconsistent and cold cracks occur. Besides defective bricks, kiln wheels and rails suffer accelerated wear. Such faults cannot be repaired online; production continues until kiln stop.
To tackle these practical challenges in brick firing plants, we redesigned the kiln car system structure. Our goal is to enhance refractory performance, long service life, and thermal sealing, with priority placed on improving long service life. Multiple structural optimization solutions have been verified and achieved positive application results.
Optimized Technical Solutions
1. Integrated Kiln Car Structural Design
The kiln car assembly includes metal frame, groove bricks, supporting protrusions on the frame, removable sand sealing plates covering the bottom side of groove bricks, and internal thermal insulation layers. The metal frame acts as the load-bearing skeleton.
Detachable sand sealing plates are vertically fixed on the end face of the kiln car frame. Mounting bases on both lower sides of the frame support vertical installation of these plates. Sand sealing plates extend from front to rear along both sides of the kiln car. The top edge covers the bottom section of groove bricks and frame end face.
Protrusions parallel to the travelling direction of the kiln car are arranged slightly inward above the frame. Groove bricks are arranged between these protrusions and fixed sand sealing plates. Groove bricks connected along the travel direction form two side walls of the kiln car, preventing backward leakage of high-temperature gas under the car.
Vertically mounted sand sealing plates support the lower outer wall of groove bricks and cover frame end surfaces. This protective structure separates the metal frame from direct high-temperature gas contact, preventing thermal expansion deformation and thermal oxidation corrosion. A refractory insulation layer is laid on top of the frame to form part of the kiln bed. Together with side wall structures, it blocks downward penetration of hot gas.
2. Multi-piece Assembled Sand Sealing Plate
Each sand sealing plate is assembled by two or more refractory panels, vertically installed and easy to disassemble. It covers the bottom of groove bricks and both end faces of the frame. This structure protects the metal frame from direct high-temperature attack. If individual refractory panels are damaged and sealing performance drops, the tunnel kiln can still maintain production. Damaged refractory pieces can be replaced conveniently during maintenance.
3. Gap Sealing with Fiber Felt
Fiber felt sealing materials are filled in all assembly gaps: joints of sand sealing plates and groove bricks, installation gaps between sand sealing plates and frame, contact areas of groove bricks and frame, groove bricks and protrusions, protrusions and insulation layers, insulation materials and frame, and seams between refractory panels of assembled sand sealing plates. This secondary sealing further prevents hot gas leakage into the space under the kiln car.
4. Embedded Anti-slip Groove Brick Design
Groove bricks are equipped with embedded structures matching the frame protrusions. The embedded connection locks groove bricks securely and prevents sliding. The detachable vertical sand sealing plates cover both ends of the frame. The metal frame stays away from direct high-temperature gas contact. Even partial refractory panels get damaged, kiln operation can continue, and component replacement remains simple.
5. Ceramic Coating for Metal Sand Sealing Plates
Metal sand sealing plates can be coated with refractory ceramic layers on the surface. Thin metal sheets with refractory ceramic coating can realize the same anti-deformation and anti-oxidation benefits.
FAQ
1.Q: How does kiln car quality affect fired brick yield rate in tunnel kiln production?
A: Stable kiln car structure and reliable thermal sealing keep uniform kiln temperature. It reduces brick deformation, cold cracks and improves finished product yield.
2. Q: What causes thermal deformation of steel kiln car frame inside tunnel kiln?
A: Direct contact with high-temperature flue gas triggers thermal expansion and thermal oxidation. Repeated thermal cycling leads to permanent deformation of the metal frame.
3. Q:What are the advantages of fiber felt sealing for kiln car gaps?
A: Fiber felt has good high-temperature resistance and elasticity. It fills irregular gaps to block hot gas leakage and improves overall thermal sealing of the kiln car.
4. Q:Why adopt modular design for sand sealing plates of brick tunnel kiln?
A:Modular refractory panels support partial replacement instead of whole-plate replacement. It shortens maintenance time and reduces production downtime for brick factories.
5. Q:Can we use ceramic coating to improve performance of metal sand sealing plates?
A:Yes. Refractory ceramic coating on metal surface isolates metal from high-temperature gas, reduces thermal oxidation and extends service life of metal sand sealing plates.
