In the alumina industry, flow measurement challenges caused by scaling.
Release time:
2026-01-05
Challenge:
In the alumina Bayer process, scaling—also known as fouling or scale deposition—poses a highly typical challenge to flow measurement. Measurement deviations directly prevent precise control of the production process, rendering full automation unattainable. Various flow‑measurement technologies have been tried, yet none has succeeded in addressing this issue.
| Technology | The impact of scarring |
| Differential pressure type (orifice plate/Venturi) | The impact is the most significant—almost “catastrophic”: scale buildup on both sides of the orifice plate leads to a change in the β value. Upstream flow field distortion → Failure of the differential pressure–flow relationship |
| Electromagnetic flowmeter | It is commonly used, yet the problem persists: scaling—acting as an insulating layer and causing changes in diameter—covers the electrodes, leading to spurious zero-point drift that is difficult to predict. The instrument itself is not defective, but it cannot meet the operating conditions. |
| Ultrasonic flow meter (clamp-on/insertion type) | Sound waves are absorbed, scattered, and refracted, leading to signal interference and reduced intensity. The system is highly sensitive to scale buildup, frequently experiencing disconnections, and exhibits poor long-term stability in high-temperature, high-alkalinity environments with significant scale formation. |
| Vortex flowmeter | Scales alter the vortex shedding characteristics, causing a shift in the frequency–flow‑rate relationship; they are suitable for clean media such as steam but are not appropriate for mother liquor or red mud slurry lines. |
Solution:
The use of Pulsar sonar flow‑measurement technology has become a widely recognized industry solution. Sonar flow meters do not come into contact with the process fluid, are resistant to scaling, feature externally mounted sensors that are immune to corrosion from high temperatures and strong alkalis, and eliminate the need for electrodes or wetted parts such as orifice plates. In alumina production, the most common installation locations include saturated liquor lines, wash liquor lines, red mud pipelines, and the piping upstream and downstream of heat exchangers.
Solution
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