Challenge

A heated process tank required the fluid temperature to be maintained within a tight spatial tolerance of ±3 °C. Following commissioning, temperature variations of up to 21.5 °C were measured within the tank. The temperature distribution therefore needed to be corrected, but installing a conventional mixing system would have required unacceptable modification of the vessel. Any solution had to be introduced through the existing small top opening.

Engineering Approach

A transient, thermal CFD study was undertaken to identify the source of the problem and to investigate solutions which would minimally disturb the fluid and which could be introduced through the small top opening without reworking the tank.

Outcome

A magnetically driven internal impeller and flow-guidance system was developed to provide gentle circulation within the tank. The impeller was driven by an external motor through the tank wall using a magnetic coupling, avoiding the need for additional tank penetrations. The completed system reduced the measured temperature variation from 21.5 °C to within the required ±3 °C tolerance.