Tham khảo tài liệu 'advanced model predictive control part 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Brainwave Model Predictive Control for the Process Industries 409 controller to minimize disturbances by adjusting outlet valve positions at the same time as the inlet valve positions are changing. Fig. 10 provides a simple diagram illustrating the application of the control loops. Level Set Fig. 10. Diagram of flotation control strategy The advanced control loops replaced the existing PID loops which the plant had previously used to maintain cell level. The PID controllers had struggled to maintain tight control and had particular difficulty stabilizing the cells after large disturbances or on plant start-ups. Fig. 11 demonstrates the improvement to the cell level control that was achieved by replacing traditional PID loops with the BrainWave loop controllers. In this case there was as much as 60 reduction in level variability as measured by standard deviation. It is suggested that improved level stability has the effect of improving mineral recovery improving product grade and reducing frother consumption. However these are difficult benefits to prove due to the problem in obtaining and collecting sufficient data where the comparisons can be made given the same operating conditions for example with the same production rates and ore types . Unfortunately to date the plant has not been able to complete such an analysis. However one obvious and easily measurable benefit came from the improved control performance on large production rate changes or plant start-ups. It was observed that the PID controllers had difficulty in stabilizing the cells after these events often cell levels could swing for as much as two hours before settling into what could be considered steady-state. This settling time was greatly reduced with the BrainWave controllers. The benefits from avoiding this loss in operating time can be directly calculated. An example calculation can be made based on the business fundamentals given in Table 2. Tonnes Milled per Day 50 000 Copper Grade Recovery
