|M.Sc Student||Ronen Doron|
|Subject||An Algorithm for the Evaluation of Controllability and|
Dynamic Resiliency of Alternative Heat Exchanger
|Department||Department of Chemical Engineering||Supervisor||Professor Daniel Lewin|
|Full Thesis text|
Heat-exchanger networks (HENs) appear frequently in process flowsheets, motivated by a desire to enhance the degree to which energy is recovered from process streams, and can often improve the economic feasibility of a process. It is often the case that several alternative HENs could be formulated to address the same processing situation, and the obvious question arises - which would be the most suitable and should be implemented, given that each HEN can be controlled by many different alternatives of bypass schemes, each resulting in a different controllability and dynamic resiliency properties?
This study presents an effective and rapid automated algorithm for the systematic screening of all possible single bypass placement combinations for a given HEN design based on a frequency domain controllability measure. The rapid calculation of all possible bypasses is done by a two-tier algorithm: an automatic modeling of the nominal HEN (all bypasses closed) is generated and linearized once, then the frequency domain controllability measure is calculated for each of the bypasses combinations based on the nominal process model. The results obtained by this algorithm highlights the dynamic resiliency limitations inherent to the specific HEN design, allowing the screening of alternative HEN designs for the most promising combination of HEN design and bypass selection. The use of the algorithm is demonstrated on small to medium-scale case studies and compared to rigorous simulation results and to published case studies.
This algorithm can be easily integrated into HEN synthesis software developed in the Technion's Process Systems Engineering (PSE) group, enabling the generation of a HEN that is not only the most cost-effective, but also the easiest to control.