Cement
Preheater cyclone
Also known as cement preheater cyclone, cyclone stage, preheater stage.
A preheater cyclone is one cyclone stage of a cement preheater tower. A 5-stage tower has 5 cyclones in series, numbered from the top (stage 1, lowest temperature) to the bottom (stage 5, hottest, just above the kiln inlet).
Stage-by-stage fouling profile
| Stage | Approximate gas temperature | Fouling intensity |
|---|---|---|
| Stage 1 (top) | 300–350 °C | Low |
| Stage 2 | 500–550 °C | Low |
| Stage 3 | 600–650 °C | Moderate |
| Stage 4 | 700–750 °C | High |
| Stage 5 (bottom) | 800–900 °C | Highest — chloride/alkali condensation peak |
Stage 4 and stage 5 cyclones are the dominant fouling problem in any cement-plant preheater. They sit in the temperature window where alkali sulphates and chlorides condense most aggressively, and they hold the calciner gas-temperature profile that determines downstream meal preheat efficiency.
Cleaning
A typical cement-preheater sonic-horn installation places multiple horns on stage 4 and stage 5 cyclones, with additional horns on the kiln-inlet riser duct and the tertiary air duct. The continuous acoustic field prevents the cohesive coatings that cause cyclone pluggage.
Related terms
Related terms
- Preheater towerA preheater tower is a vertical stack of cyclone separators that pre-heats raw meal with kiln exhaust gas before it enters the rotary kiln. The most fouling-prone section of any cement plant.
- Cyclone separatorA cyclone separator removes particulate from a gas stream by centrifugal force. Wall build-up and re-entrainment from the dipleg are the dominant operational issues.
- Build-up, coating and accretionBuild-up, coating and accretion are interchangeable terms for accumulated deposits on cement-plant gas-path surfaces. The leading cause of kiln stops in cement manufacture.
- Sonic hornA sonic horn is a pneumatically-driven low-frequency sound emitter (typically 60–400 Hz at 140–180 dB SPL) used to dislodge particulate fouling from boilers, ESPs, baghouses and process vessels.