SYNTHESIS OF ENERGY EFFICIENT COMPLEX SEPARATION NETWORKS

1. Level I: Find all possible basics configurations Implicit Differentiation Mixed Integer Linear Program Basic Config. Level II: Identify the feasible complex column Pinch Point Supply Temperature Design Specification Feasible BPD Level III : Obtain optimal designs Output Input Flow rate tray# Specification Output Comp. profile Each individual different design (sequence + operating conditions) Each random initial guess for integer variables, x, will generate one possible structure K individuals MASTER Basic Structure Feasible Case MinBPD = 0 Infeasible Case MinBPD > 0 Population Feasibility test High performance Inverse problem SYNTHESIS OF ENERGY EFFICIENT COMPLEX SEPARATION NETWORKS Seon B. Kim, Gerardo J. Ruiz Jeonghwa Moon, Libin Zhang and Andreas A. LinningerLaboratory for Product and Process Design Departments of Chemical Engineering and Bioengineering, University of Illinois at Chicago, Chicago, IL, 60607, USA10th International Symposium on Process Systems Engineering, August 16-20, 2009, Salvador, Bahia, Brazil B B B D A A C C A C Motivation and Objectives Complex Column Synthesis Algorithm Motivation Distillation occupies in chemical process: • 40-70% of capital and operating costs • 60% of the total process energy • 4% of total energy consumption in United States • Atmospheric carbon emissions 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 Objectives • Develop computer-aided systematic design procedures to prevent numerical failures associated with the extraordinary sensitivity of column profile calculations. • Massive size reductions enabled by a new column profile computation algorithm called Temperature Collocation • Synthesize separation networks with realistic column profiles • Realizable column profiles validated with industrially accepted simulation software such as Aspen HYSYS Global Design Procedure Basic complex configuration: quaternary system Basic complex column configurations Generic Structure Synthesis Network Task Optimization Using Difference Point Equations Find Feasibility of Two Column Sections Considering Operating and Capital Cost Obtain Optimal Design Complex Column Profiles Rigorous Feasibility Test 1 According to the generalization of the minimum bubble point distance approach, a complex column k is feasible if the sum of all profile distances of all adjacent sections i and i+1 is within a small tolerance () close tozero. The entire network is feasible if all its columns are feasible as: Temperature Collocation of a General Column Section Column Section profile: Rigorous Feasibility Test 2 Reduced Search Space Bubble Point Temperature Distance map shows the minimum composition distance between two adjacent sections. The minimum bubble point distance (BPD) of 3.3586e-004 is localized at r= 15.05 and BPT= 79.1844 C. C S3 B S2 S4 S1 Case Study - Aspen HYSYS Validation of Complex Network Case Study - Separation of Quaternary Mixture A A quaternary mixture of methanol, ethanol, 1-propanol, and acetic acid was studied. This complex network uses two simple columns and one complex column. The complex configuration analyzed uses half total vapor rate and saves 20% of total costs compared to the simple column configuration. AspenHYSYS simulation of composition and temperature profiles Temperature Collocation composition profiles Conclusions Acknowledgements • Dr. Angelo Lucia (University of Rhode Island) • Dr. David Glasser (University of the Witwatersrand) • DOE Grant: DE-FG36-06GO16104 • Dr. Rakesh Agrawal (Purdue University) • Dr. Chau-Chyun Chen (Aspen Tech.) • Temperature collocation and minimum bubble point distance (MIDI) algorithm were effective to find a feasible separation by intercepting profiles. • The first case study demonstrates the potential to save 50% in energy using a complex column network compared to the simple column configuration. • The second case study 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 References Agrawal, R. (2003). "Synthesis of multicomponent distillation column configurations." AIChE J49(2): 379-401. Tapp, M., S.T. Holland, D. Hildebrandt, and D. Glasser, Column Profile Maps. 1. Derivation and Interpretation.I&EC Research, 2004. 43(2): p. 364-374. Zhang, L. and A. A. Linninger (2004). "Temperature collocation algorithm for fast and robust distillation design." I&EC Research43(12): 3163-3182. Zhang, L. and A. A. Linninger (2006). "Towards computer-aided separation synthesis." AIChE J52(4): 1392-1409.