SCC Outlet Duct Brick Damage

Secondary Combustion Chamber · Outlet Duct

Problem Details

Background

The SCC outlet duct conveys hot flue gas (900–1100℃, dust-laden, corrosive) from the secondary combustion chamber to the waste-heat boiler. The brick lining long-term bears hot-gas scouring, temperature swings and corrosion; lining damage is a common incineration issue.

Failure Mechanism

Hot-gas scouring: high-temperature gas carrying ash flows through at high speed, thermally scouring and abrading the lining. Corrosion: acid gases (HCl, SO₂) and alkali condense and attack in cooler duct zones. Thermal shock: ignition, shutdown and load swings cause rapid temperature changes, shocking the lining. Structural stress: duct thermal expansion and support displacement impose stress.

Consequences

After damage, duct wall temperature rises, corrosion worsens and leakage risk rises; fallen bricks may plug the WHB inlet or damage equipment, forcing shutdown for repair.

Solution

Material Selection and Parameters

Select the outlet duct for "high wear resistance + corrosion resistance":

Material system: high-alumina brick (Al₂O₃≥55%) or SiC brick (SiC≥85%). High-alumina offers value; SiC resists wear and conducts heat for hot scouring zones; acid-resistant grades or liners in cold-corrosion zones;
Structural design: thicken elbows and transitions or fit wear liners; insulation reduces heat loss and condensation;
Joint materials: lay with high-alumina mortar and tight joints.

Installation Essentials

Masonry control: lay with staggered joints, full mortar and joints ≤2mm. Anchoring: anchor the brick lining to the duct wall reliably. Bake-out: follow the curve to avoid residual moisture in mortar.

Maintenance

Monitor duct wall temperature and gas resistance; investigate on anomalies. At maintenance, measure residual thickness and patch or replace thinned zones; record corrosion and wear data to optimize grade and insulation design.

Recommended Products

Featured

High-Alumina Brick LZ-55

High-alumina brick LZ-55 (Al₂O₃≥55%) with refractoriness ≥1770℃ offers dense structure, wear resistance against gas scouring and combined cold/hot strength—one of the most widely used shaped refractories.

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Silicon Carbide Brick

Silicon carbide brick (SiC≥85%, refractoriness ≥1900℃, CCS≥120MPa) offers high thermal conductivity, extreme wear resistance, thermal-shock resistance and molten-salt resistance—preferred for waste incineration and hot abrasion duties.