Gain scheduling adaptive control applied to a particular mixer-settler equipment

•An interface level sensor was developed based on capture and treatment of images.•A computational routine was created in Fortran language to control interface level.•The feedback loop was tuned using direct synthesis to determine the PID parameters.•The conventional controller was not able to counteract disturbances more drastic.•The adaptive controller was able to counteract such disturbances.

The mixer-settler based on phase inversion (MSBPI) is a system used for treatment of wastewaters in order to reduce the content of oils and greases from wastewaters produced in oil industry. Its operation principle combines mixing, extraction and separation by decantation in a unique process. In particular, for control purpose, the level of the interface between organic solvent and water, in the separation section, is a critical variable to guarantee performance and security during operation of the MSBPI. In this work, an image-based detector to monitor the organic solvent–water interface level is proposed and a feedback control loop for the process is presented. Initially, a conventional controller (PID) was implemented and, subsequently, a strategy of gain scheduling adaptive control was developed in order to improve the process response in closed-loop. The experimental results showed that the adaptive control presented an efficient performance, even when disturbances of significant magnitude were applied to the process.