Model predictive brix control
The concept of model predictive control is extended here to brix control, where the advantages of this form of control are clearer. Currently, the syrup brix leaving the triangle evaporator station is controlled by manipulating the flow rate of threating vapour to the third effect of each train. In triangle this vapour is vapour two; the vapour evolved form the second effect evaporators (v2). The layout of the triangle evaporator station is shown in figure 5 below.
Although this control system involves only two outputs, syrup brix and clear juice flow rate, it is still essential that this control layer should be able to anticipate and handle constraints. At triangle ltd. The in touch scanning, control and data acquisition (SCADA) System has recently been installed, which provides online readings of the most significant three disturbances, i.e. juice flow rate, exhaust steam pressure and final effect pressure. The effects of these inputs are more easily included in the DMC formulation, rather than as a series of trims and feed forward gains, which would be necessary for PI control. It is for these reasons that a DMC control has been selected.