IMPLEMENTATION OF MODEL PREDICTIVE CONTROLLER ON HID AND SEEDWASH UNITS AT QAL

As part of Queensland Alumina Limited (QAL)’s Advanced Process Control (APC) projects program, Honeywell’s Profit Controller application has been implemented on Heat Interchange Department (HID) and Seedwash units in the Precipitation area at QAL in 2016/17. This paper provides an overview of the HID APC and the Seedwash APC applications covering the challenges faced, key objectives and Model Predictive Control (MPC) features used and benefits achieved.

HID MPC application involved significant complexity due to plant configuration, missing instrumentation, a large number of tanks for level control and process equipment constraints such as cavitation of the Spent Liquor pumps. It also involved interaction with existing Precipitation APC application. Seedwash APC was implemented as a fast track project as it was a bottleneck to plant production and it had complex interactions with DCS overrides for equipment and process constraints. Both the APC projects have yielded considerable benefits and have eased plant operations.