Use of orthogonal collocation in the dynamic simulation of staged separation processes

• Main Author: Matandos, Marcio
• Other Authors: Levien, Keith L.
• Language: en_US
• Published: 2013
• Subjects: Distillation > Mathematical models; Separation (Technology) > Mathematical models; Orthogonal polynomials; Collocation methods
• Online Access: http://hdl.handle.net/1957/36669

Two basic approaches to reduce computational requirements for solving distillation problems have been studied: simplifications of the model based on physical approximations and order reduction techniques based on numerical approximations. Several problems have been studied using full and reduced-order techniques along with the following distillation models: Constant Molar Overflow, Constant Molar Holdup and Time-Dependent Molar Holdup. Steady-state results show excellent agreement in the profiles obtained using orthogonal collocation and demonstrate that with an order reduction of up to 54%, reduced-order models yield better results than physically simpler models. Step responses demonstrate that with a reduction in computing time of the order of 60% the method still provides better dynamic simulations than those obtained using physical simplifications. Frequency response data obtained from pulse tests has been used to verify that reduced-order solutions preserve the dynamic characteristics of the original full-order system while physical simplifications do not. The orthogonal collocation technique is also applied to a coupled columns scheme with good results. === Graduation date: 1992