Corundum-Mullite Castable
Corundum-mullite castable combines the hot strength of corundum with the thermal-shock resistance of mullite. Al₂O₃≥80%, 1700℃ max service.
Learn More →Radiant Section Lining Spalling
Ethylene Cracking Furnace · Radiant Section
Problem Details
Background
The radiant section of an ethylene cracking furnace is the core cracking zone. Furnace tube surfaces reach 1050–1150℃; the lining long-term bears high-temperature radiation, flue-gas scouring and severe thermal cycling from periodic decoking. Lining spalling and crack growth is the main failure mode.
Failure Mechanism
High-temperature radiation and over-heating: radiant-section temperature is high; the lining runs hot long-term, over-firing and losing strength. Thermal shock: decoking (steam and air decoking) periodically swings furnace temperature sharply; thermal-shock stress cracks and spalls the lining. Gas scouring: high-velocity gas and combustion products scour the lining. Anchor failure: anchors oxidize and fail at high temperature; the lining loses restraint and spalls.
Consequences
After radiant-section spalling, heat loss rises and furnace wall temperature increases, hurting cracking efficiency and tube life; severe spalling may drop lining onto tubes or plug flues, forcing shutdown and shortening the ethylene plant operating cycle.
Solution
Material Selection and Parameters
Select radiant-section lining for "high-temperature resistance + thermal-shock resistance":
- Material system: low-cement corundum-mullite castable (Al₂O₃≥80%) or mullite castable (Al₂O₃≥75%). Corundum-mullite combines hot strength and thermal-shock resistance for radiant-section thermal cycling;
- Anchors: heat-resistant steel anchors matched to furnace temperature, spaced per design with ceramic caps;
- Thickness design: size working and insulation layers by temperature gradient to reduce heat loss.
Installation Essentials
Formwork casting: cast large radiant-section areas continuously with joints away from stress concentration. Vibration: vibrate fully. Water control: follow the datasheet for hot performance. Bake-out: follow the heat-up curve strictly and complete dehydration before commissioning.
Maintenance
Control furnace temperature and decoking parameters, standardizing decoking heating/cooling rates to reduce thermal shock; inspect lining surface and wall temperature regularly. At maintenance, patch spalled zones, replace failed anchors and record lining life to optimize grade and practice.
Recommended Products
Low-Cement High-Alumina Castable
Low-cement high-alumina castable with CaO≤2.5% and Al₂O₃≥65% reaches 1650℃ service. Dense micro-powder grading lowers porosity and raises hot strength.
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Featured
Mullite Castable
Mullite castable with mullite clinker or synthetic aggregate, Al₂O₃≥75%, 1650℃ max service. High refractoriness-under-load with excellent creep and thermal-shock resistance for long-term load-bearing at temperature.
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