Glossary
Fouling
Scaling (process)
Also known as scale deposit, mineral scale.
Scaling is the deposition of inorganic mineral salts (calcium carbonate, calcium sulphate, silica, magnesium silicate) on heat-transfer surfaces — typically the liquid side of an exchanger or boiler tube. Scaling is the dominant fouling mechanism in cooling-water systems, multi-effect evaporators, water-side boiler tubes and process heat exchangers.
Distinguishing scaling from gas-side fouling
| Attribute | Scaling | Gas-side fouling |
|---|---|---|
| Side of the tube | Liquid side | Gas side |
| Mechanism | Inverse-solubility chemistry | Particulate adhesion |
| Cleaning | Chemical, hydroblast | Mechanical, acoustic, steam |
| Sonic-horn applicability | None | Where dry, friable |
Sonic horns address gas-side fouling, not water-side scaling. Liquid-side scale removal is the province of chemical cleaning campaigns, hydroblasting and other specialised techniques.
Related terms
Related terms
- Fouling (general)Fouling is the accumulation of unwanted deposits on process-equipment surfaces. The general umbrella term covering slagging, scaling, coking, sintering and many other specific mechanisms.
- Multi-effect evaporatorA multi-effect evaporator train concentrates weak kraft black liquor from 15% solids to 70-75% solids before it can be burned in the recovery boiler.
- Cold-end corrosion and dew-point corrosionCold-end corrosion is the attack on air-heater and economiser surfaces below the acid dew point, where SO3 condenses as sulphuric acid. The leading cold-end failure mechanism.