Automatic and Rigorous Flowsheet Design of Energy Efficient Separation Process

1. Level I: Find all possible basics configurations Implicit Differentiation Mixed Integer Linear Program Basic Config. Column Section profile: Level II: Identify the feasible complex column Pinch Point Supply Temperature Design Specification Feasible BPD Level III : Obtain optimal designs Output Flow rate tray# Input Specification Output Comp. profile Automatic and Rigorous Flowsheet Design of Energy Efficient Separation Process Seon B. Kim and Andreas A. LinningerLaboratory for Product and Process Design, Departments of Chemical and Bio-Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA AIChE Spring Meeting, March 13 – 17, 2011, Chicago, IL Temperature Global Design Procedure Methodology 2 – Design Procedure Methodology 1 – Column Profiles Motivation Basic complex column configurations Generic Structure Synthesis Network Task Optimization • Distillation occupies in chemical process: • 40-70% of capital and operating costs • 60% of the total process energy • 4% of total energy consumption in the United States • There is a need for a redefinition of the design objectives for industrial separations with a new focus on energy conservation and the emission reduction using complex column configurations have the potential of achieving up to 70% energy savings over simple column networks • Inverse Design of Distillation Column • Starting with the desired design specification of product purity requires that each column of the network is feasible • Feasible design – Interception of profiles of both adjacent sections • Bubble Point Distance Criterion • Profile Intersection Index – distance between rectifying and stripping profiles at identical bubble point temperature • Realizable column profiles • Temperature Collocation of a General Column Section • Massive size reductions enabled by a new column profile computation algorithm called Temperature Collocation • Basic Column Configuration - Quaternary System • Among total 18 basic structures for the mixture of 4 components, 9 structures were tested Using Difference Point Equations Find Feasibility of Two Column Sections Considering Operating and Capital Cost Obtain Optimal Design Column II Column III Column I Temperature Column II Column III Column I Conclusions Results • Temperature collocation and minimum bubble point distance algorithm were effective to find a feasible separation by intercepting profiles. • Case studies of 9 networks demonstrate the potential to save 72% in energy using a complex column network compared to the simple column networks. • Case studies of 10 components mixtures and side column design show the robustness of the proposed methodologies for the various distillation-based separations. • We demonstrates the current state of the art of separation synthesis in conjunction with computer simulations to fully integrate complex separation networks. • The seamless integration of rigorous flowsheet simulators to validate the predictive results of our scientific method was demonstrated. Feasible Column Design Flowsheet Simulator Validation • Dr. Angelo Lucia (University of Rhode Island) • Dr. Diane Hildebrandt (University of the Witwatersrand) • DOE Grant: DE-FG36-06GO16104 • Dr. Rakesh Agrawal (Purdue University) • Dr. Chau-Chyun Chen (Aspen Tech.) Feasible Design (r=3.5) Infeasible Design (r=2.5) Acknowledgements Feasible Column Network Design Feasible Column Designs for 10 Comp. Mixtures and side column Direct Split Indirect Split Sloppy Split Side Stripper Column I Column II Column III References Agrawal, R. “Synthesis of multicomponent distillation column configurations.” AIChE J, 2003, 49(2): 379-401. Tapp, M., Holland, S.T., Hildebrandt, D., and Glasser, D. “Column Profile Maps. 1. Derivation and Interpretation.” I&EC Research, 2004, 43(2): 364-374. Zhang, L and Linninger, A. A. “Temperature collocation algorithm for fast and robust distillation design." I&EC Research, 2004, 43(12): 3163-3182. Zhang, L and Linninger, A. A. “Towards computer-aided separation synthesis." AIChE J, 2006, 52(4): 1392-1409. Kim, S., Luiz, G., and Linninger, A. A. “Rigorous Separation Design. 1. Multicomponent Mixtures, Nonideal Mixtures, and Prefractionating Column Networks”, I&EC Reasearch, 2010, 49(14): 6499-6513. Kim, S., and Linninger, A. A. “Rigorous Separation Design. 2. Network Design Solutions for Mixtures with Various Volatility Differences and Feed Compositions”, I&EC Reasearch, 2010, 49(18): 8670-8684. Operating Cost (vapor flow, kmol/h)