Dynamics and control of a process with recycle streams

The dynamic behavior and the control of a heating system with recycle streams are analyzed using a nonlinear grey-box model. The analysis led to the conclusion that the system can become unstable at low f,equencies. The instability was verified in experiments and possible solutions for this problem are discussed. A control strategy that works for a wide range of distilling mixtures and operating conditions is derived. Finally. startup procedure is presented.