Typical Applications - Air-Core Vortex Detection
Investigations into air-core vortex effects of two types of impeller (Rushton turbine and A310 Lightin impeller (both 400mm dia.)) in an un-baffled stirred vessel of 1.5m i.d. have been reported . Eight axial planes, each comprised of a 16-electrode stainless steel sensor array were retrofitted to the tank. The two-dimensional images were reconstructed using an air-core quantitative algorithm. Three-dimensional images, created using linear interpolation of the eight two-dimensional cross-sections permit the observation of non-stationary behaviour, producing a good interpretation of the non-symmetrical vortices. The ERT images produced were capable of distinguishing between the two impeller types investigated. In addition to being of use for CFD validation and further model development, this type of application has been employed in the nuclear reprocessing industry to examine the position of a mechanically induced vortex inside a crystallisation reactor . The presence and depth of the vortex provides information on overall reactor performance, and should the vortex exceed preset parameters (either at low or high end) then an alarm is triggered, allowing operator intervention. Due to hazardous nature of the material, EIT provides a safe means of monitoring, with the added advantage that the simple and inexpensive hardware is ideally suited to the hostile environment in which it operates.
The vortex monitoring device with EIT was installed at the thermal oxide reprocessing plant (THORP), Sellafield, UK for remotely monitoring the performance of continuous stirred tanks for precipitation process of radioactive materials with 3.5m nitric acid.
Fig. 2 Tomograph of Air-Core Vortex Detection Process
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