ROBUST MULTIVARIABLE PREDICTIVE CONTROL TECHNOLOGY IMPLEMENTATION IN AN ALUMINA DIGESTION UNIT

Oliveira, A., Batista, J., Ribero, M., Charr, J. and Lopes, R.

Significant economic savings for alumina plants can be made, through the utilisation of new control technologies, that use the existing infrastructure and require a reduced support team. The global market and suppliers consolidation has created a more competitive environment, which drives the need for production and performance optimisation. Multivariable predictive control technology becomes one of the main tools to optimise investment performance. This paper will discuss the application and benefits of this technology to alumina digestion units.

The APC philosophy for alumina digestion is based on process variability reduction, and consequently it optimises operations against the plant constraints. Since the alumina – caustic ratio (A/TC) is the key plant variable, it has a fundamental role in this variability reduction.

The project implementation took approximately 7 months and generated a 1.02% increase in production.