Hood Side Wall Thermal Shock Cracking

Kiln Hood · Side Wall

Problem Details

Background

The kiln hood side walls sit at both sides of the kiln outlet, long-term bearing high-temperature radiation, secondary-air scouring and clinker splash. Side-wall bricks thermally crack and spall under temperature swings and mechanical action—a weak point of hood linings.

Failure Mechanism

High-temperature radiation: flame and hot clinker continuously radiate the walls; brick temperature and thermal load are high. Thermal shock: kiln swings and start/stop cause rapid temperature changes, thermally cracking the bricks. Gas scouring: secondary air carrying dust scours the walls. Clinker splash: clinker particles impact the walls. Structural stress: hood deformation and brick expansion mismatch create stress.

Consequences

After thermal cracking, the hood shell overheats and deforms and sealing degrades; broken bricks may fall into the grate cooler or damage equipment, forcing kiln shutdown for repair.

Solution

Material Selection and Parameters

Select hood side walls for "high thermal-shock resistance + high-temperature resistance":

Material system: spalling-resistant high-alumina brick (Al₂O₃≥70%, ZrO₂ 3–6%) or mullite brick (Al₂O₃≥75%). ZrO₂-toughened high-alumina resists spalling; mullite resists high temperature and thermal shock;
Structural design: reliably connect wall bricks with the roof lining; reserve expansion joints per design;
Joint materials: lay with high-alumina mortar and tight joints.

Installation Essentials

Masonry control: lay with staggered joints, full mortar and joints ≤2mm. Expansion joints: position and width per drawing. Locking: lock circumferentially against loosening. Bake-out: follow the curve to avoid residual moisture in mortar.

Maintenance

Stabilize kiln operation to reduce sharp temperature swings; inspect wall bricks and shell temperature regularly, replacing cracked bricks promptly. At maintenance, check the wall-roof junction and assess overall hood lining condition.

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 →

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Mullite Brick

Mullite brick with mullite as the main phase (Al₂O₃≥75%, refractoriness ≥1850℃, RUL ≥1650℃) offers high-temperature volume stability with excellent thermal-shock and creep resistance.