In the alumina industry, flow measurement challenges caused by scaling.
Release time:
2026-01-05
Challenge:
In the Bayer process for alumina production, scaling—also known as fouling or deposition—is a highly typical issue that interferes with flow measurement. Deviations in flow measurement directly lead to inaccurate control of the production process, making it impossible to achieve true automation in production. Although various flow measurement technologies have been tried, none have yet succeeded in resolving this problem.
| Technology | The impact of scarring |
| Differential pressure type (orifice/venturi) | The impact is the most significant—almost “disastrous”—with scarring forming upstream and downstream of the orifice plate, leading to a change in the β value. Upstream flow field distortion → failure of the differential pressure–flow relationship |
| Electromagnetic flowmeter | Although commonly used, the problem persists: scar formation equals an insulating layer equals changes in caliber. The scar covering the electrode causes false zero-point drift that’s impossible to predict. The instrument isn’t broken, but it can no longer meet the operational conditions. |
| Ultrasonic Flow Meter (External Clamp/Insertion) | Sound waves are absorbed, scattered, and their angles of refraction are altered, leading to signal interference and a reduction in signal strength. The system is extremely sensitive to scaling, often experiencing frequent disconnections. In environments characterized by high temperature, high alkalinity, and scaling, its long-term stability is poor. |
| Vortex flow meter | The formation of scars alters the vortex shedding characteristics and causes a shift in the frequency-flow relationship. This configuration is suitable for clean media such as steam but is not appropriate for mother liquor and red mud slurry lines. |
Solution:
The adoption of Pulsar sonar flow technology has become a widely recognized solution in the industry. Sonar flow meters do not come into contact with the material being measured, are resistant to scaling, and feature externally mounted sensors that are immune to corrosion from high temperatures and strong alkalis. They also lack electrodes or wetted components such as orifice plates. In the alumina production process, the most common installation locations for these flow meters are pipelines carrying saturated liquor, washing solutions, and red mud, as well as pipes before and after heat exchangers.
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