Feedforward control is a control strategy where the control action is taken based on the anticipated future behavior of the system, rather than just its current behavior. In this approach, the control action is taken based on the predicted future output of the system, based on the input signal. An example of feedforward control in a heat exchanger can be as follows: Let's consider a heat exchanger system, where the input temperature is constantly changing, and the output temperature needs to be maintained at a constant value. In this case, the feedforward control strategy can be used to predict the future output temperature based on the current input temperature, and adjust the control action accordingly. For example, if the input temperature is increasing, the control action can be to increase the flow of coolant, thus compensating for the increase in input temperature, and maintaining the output temperature at the desired value. In conclusion, feedforward control provides improved performance compared to feedback control in systems where the future behavior of the system can be predicted based on the input signal. In distillation, feedforward control is implemented by using the temperature or composition of the distillate as the manipulated variable, based on the expected change in the feed composition. For example, if the feed composition changes and the concentration of a certain component increases, the control system can adjust the temperature of the distillate to reduce the concentration of that component in the product. Feedforward control in distillation has several advantages over traditional feedback control, including:
Faster response time: Since the control action is taken based on the predicted future behavior of the system, the response time is much faster than feedback control.
Improved product quality: By anticipating changes in the process and taking corrective action before the product quality is affected, feedforward control helps to maintain the desired product quality more effectively.
Increased process stability: By compensating for disturbances before they affect the process, feedforward control helps to increase the stability of the distillation process.
In conclusion, feedforward control is an effective strategy for controlling distillation processes and maintaining the desired product quality. By anticipating changes in the process and taking corrective action in advance, feedforward control provides improved performance and increased process stability compared to traditional feedback control.