Roller Kiln Wall Thermal Shock Cracking

Roller Kiln · Walls

Problem Details

Background

Roller kiln walls insulate and seal the kiln, long-term bearing high temperature (1200–1300℃ in the firing zone), heating/cooling cycles and kiln atmosphere. Wall-brick thermal cracking and spalling are common issues, affecting temperature uniformity and sealing.

Failure Mechanism

Thermal shock: heating/cooling cycles impose thermal-shock stress on wall bricks, cracking them over repeated action. Uneven temperature: uneven kiln temperature over-heats and stress-concentrates local walls. Structural stress: kiln deformation and brick expansion mismatch create stress. Atmosphere action: kiln atmosphere attacks wall bricks.

Consequences

After cracking, kiln sealing degrades, heat is lost and temperature uniformity worsens, hurting firing quality; severe cracking lets bricks fall onto products and rollers, forcing shutdown for repair.

Solution

Material Selection and Parameters

Select kiln walls for "high thermal-shock resistance + insulation":

Material system: spalling-resistant high-alumina brick (Al₂O₃≥70%, ZrO₂ 3–6%) for firing-zone walls—outstanding spalling resistance; lightweight high-alumina insulating brick (Al₂O₃≥48%) for insulation;
Structural design: "working brick + insulating brick" composite—working bricks resist thermal shock, insulating bricks insulate; reserve expansion joints per design;
Joint materials: lay with matching mortar and tight joints.

Installation Essentials

Masonry control: lay with staggered joints, full mortar and joints ≤2mm. Expansion joints: construct per drawing. Bake-out: follow the curve to avoid residual moisture in mortar.

Maintenance

Keep kiln temperature uniform and standardize heating/cooling; inspect wall bricks regularly and replace cracked bricks promptly. At maintenance, check wall-roof junctions to keep the kiln well sealed.

Recommended Products

Spalling-Resistant High-Alumina Brick

Spalling-resistant high-alumina brick introduces ZrO₂ (3-6%) for transformation and microcrack toughening. Al₂O₃≥70%, thermal-shock stability ≥15 cycles, greatly improved resistance to structural spalling under frequent temperature cycling.

Learn More →

Lightweight High-Alumina Insulating Brick

Lightweight high-alumina insulating brick (Al₂O₃≥48%, 1500℃ max, bulk density 0.8-1.2 g/cm³, conductivity ≤0.5 W/(m·K)) saves energy with light weight and low thermal conductivity.