D epartment of Chemical Engineering, Budapest University of Technology and Economics, H-1521 Budapest, Hungary

1. Department of Chemical Engineering, Budapest University of Technology and Economics, H-1521 Budapest, Hungary Research activities CAPE-Forum, Veszprem, 2004

2. DISTILLATION AND ABSORPTION • Determination of Vapour-Liquid Equilibria and design of Packed Columns. • Development on distillation and absorption technologies • Modelling and calculation of thermodynamic properties • Modelling of batch and continuous countercurrent separation processes • EXTRACTION AND LEACHING • Kinetics of Soxhlet-type and Supercritical Solid-Liquid Extraction of Natural Products. Mathematical modelling and optimization of the process. • Supercritical fluid extraction equipment and R&D capabilities • REACTIONS • Mathematical modelling of residence time distribution and chemical reactions • MIXING OF LIQUIDS

3. PROCESS DESIGN AND INTEGRATION • Feasibility of distillation for non/ideal systems • Hybrid separation systems • Reactive distillation • Design of Energy Efficient Distillation Processes • Energy integrated distillation system design enhanced by heat pumping and dividing wall columns • Energy recovery systems • A global approach to the synthesis and preliminary design of • integrated total flow-sheets • Process Integration in Refineries for Energy and Environmental Management

4. CONTROL AND OPERABILITY • Assessing plant operability during process design • Transformation of Distillation Control Structures • Control of units in recycle • ENVIRONMENTALS • Waste reduction in the Chemical Industry • CLEAN TECHNOLOGIES • Membrane separations • Cleaning of waste water with physico-chemical tools. • Solvent recovery • Synthesis of mass exchange networks with mixed integer nonlinear programming • Economic and controllability study of energy integrated separation schemes • Process synthesis of chemical plants

5. Department of Chemical Engineering, Budapest University of Technology and Economics, H-1521 Budapest, Hungary Selected topics of our CAPE activities: Analysis of energy integrated separations and Synthesis of mass exchange networks Mizsey, P., Z. Szitkai, Z. Fonyo CAPE Forum 2004 Challenges for East-West European Cooperation in Process Modelling, Control, Synthesis and Optimization 13-14 February 2004, Veszprém, Hungary

6. Posters:

7. Integrated process design • Challenge in chemical engineering • Economical and environmental aspects • Heat integration (HEN) & mass integration (MEN) • Several synthesis strategies • The design needs CAPE

8. Analysis of energy integrated separations (distillation based) CAPE Forum 2004 Challenges for East-West European Cooperation in Process Modelling, Control, Synthesis and Optimization 13-14 February 2004, Veszprém, Hungary Budapest University of Technology and Economics Department of Chemical Engineering

9. Classical distillation schemes for ternary mixture Base case for comparison Direct sequence Indirect sequence

10. Heat integration Forward heat integration direct sequence (DQF) Backward heat integration direct sequence (DQB)

11. Thermocoupling, Petlyuk column or dividing wall column (SP)

12. Sloppy separation sequences Forward heat integration (SQF)

13. Sloppy separation sequence, backward heat integration (SQB)

14. Case study Mixture: ethanol n-propanol n-butanol Equimolar feed composition (0.333, 0.333, 0,333) Product purity specification: 99 m%

15. Comparison of TAC savings (%) I D base case DQF DQB SP SQF SQB

16. Controllability study • Selection of controlled variables & manipulated variables, • degrees of freedom analysis • steady state indices: Niederlinski index, Morari index, • condition number, relative gain array • dynamic evaluation: open-loop & closed-loop

17. Steady state controllability indices

18. Evaluation of steady state indices • base case (D) and heat-integrated schemes (DQF and DQB) • show less interactions, • (D1-L2-B2) manipulated set proves to be better than (L1-D2-Q2) • and (L1-D2-B2) for D, DQF and DQB • serious interactions can be expected for the sloppy schemes • (SQF & SQB) and for the Petlyuk column (SP)

19. Dynamic simulations • Open composition control loops: • quite similar dynamic behaviour but • sloppy backward heat integrated (SQB) is the slowest scheme

20. Petlyuk column, open loop, feed rate

21. Heat integrated (DQB) column, open loop, feed rate

22. Evaluation of closed composition control loops: overshoot, settling time, and their product are evaluated

23. Petlyuk column, closed loop (L-S-B), feed rate

24. Heat integrated (DQB) column, closed loop (D-L-B), feed rate

25. Closed loop dynamic simulations • Simple energy integration (heat integration) doesn’t influence • dynamic behaviour compared to the non-integrated base case • more complicated systems: higher detuning factor is needed • due to stronger interactions (they became slower in closed loop) • The cases, where material and energy flows (energy integration) • go into the same direction (DQF, SQF), are better than the opposite

26. Conclusions • with energy integration about 35% TAC saving can be realised • simple heat integration shows the best economic and • controllability features • sloppy schemes show good economic features but the selection is • made according to their different controllability features (SQF,SQB) • example also for the complexity of the process design: economic • and controllability features are to be simultaneously handled

27. Feed mix D3 D1 Group 2 D2 F2 C2 C3 Water F1 B2 B3 C1 IPAC ETAC (MEK) ETOH 95 w% W1 H2O New directions: control of units in recycle Example:

28. Synthesis of Mass Exchange Networks Using Mathematical Programming CAPE Forum 2004 Challenges for East-West European Cooperation in Process Modelling, Control, Synthesis and Optimization 13-14 February 2004, Veszprém, Hungary Budapest University of Technology and Economics Department of Chemical Engineering

29. Outline I. Mass Exchange Network Synthesis (MENS) A Extension of the MINLP model of Papalexandri et al. (1994) B Comparison of the advanced pinch method of Hallale and Fraser (2000) and the extended model of Papalexandri et al. C New, fairly linear MINLP model for MENS II. Rigorous MINLP model for the design of distillation-pervaporation systems III. Rigorous MINLP model for the design of wastewater strippers Approach: Mixed Integer Nonlinear Programming (MINLP) optimisation software: GAMS / DICOPT

30. I. Mass Exchange Network Synthesis El-Halwagi and Manousiouthakis, AIChE Journal, Vol 35, No.8, pp. 1233-1244 Mass integration for the analogy of the concept of heat integration. Absorber, extractor etc. network synthesis (MSAs) The synthesis task: Stream data + equipment data + equilibrium data + costing Network structure lean stream flow rates min (Total Annual Cost, TAC) Previous work: sequential mathematical programming methods El-Halwagi (1997), Garrison et al. (1995) Alva-Argaez et al. (1999) early pinch methods (no supertargeting) Water pinch: Wang & Smith (1994, 1995), Kuo & Smith (1998) El-Halwagi & Manousiouthakis (1989a) El-Halwagi (1997) advanced pinch method (includes supertargeting) Hallale & Fraser (1998, 2000) simultaneous mathematical programming models Papalexandri et al. (1994) Papalexandri & Pistikopoulos (1995, 1996) Comeaux (2000); Wastewater: Benkő, Rév & Fonyó (2000)

31. I/A Extensions of the MINLP model of Papalexandri et al. (1994) • Integer stage numbers • Generation of feasible initial values • Kremser equation: Removable discontinuity at A=1 yi*=mijxj*+bij • Previous mathematical programming models for MENS • assumed that A is always greater than 1 • Numerical difficulty when using GAMS

32. Adopted literature methods • Big-M formulation • Multi-M formulation • a Convex-hull like formulation • Raman & Grossmann (1991) • Simple logic formulation are linear but use 3 binary variables New method Advantages: 1. faster 2. larger problems can be solved nonlinear but uses 1 binary variable only (the models are nonconvex anyway) Large nonconvex MINLP problems solved by DICOPT++: There exists a critical upper limit of the number of binary variables

33. I/B Comparison of the advanced pinch method of Hallale and Fraser (2000) and the extended model of Papalexandri et al. (1994) 13 example problems have been solved The two methods perform more or less the same. Why are the MINLP solutions not always better? The MINLP model is nonconvex.

34. I/C New, fairly linear MINLP model for MENS Similar to the HEN superstructure of Yee & Grossmann (1990) The stagewise superstructure enables almost linear mass balance formulation

35. Model equations minimise s.t. big-M constraints for the existenxe of the units mass balances driving force constraints constraints on the number of existing units concentration constraints Chen’s approximation for the log mean conc differences calculation of the mass of the exchangers Only the lean stream mass balances are bilinear

36. Example problems Example 4.1 (Hallale, 1998) Extensions: stagewise exchangers, multiple components The new model is most suitable for solving single component MENS problems, where packed columns are used exclusively. In this case, no special initialization is needed. Two component example

37. II. Rigorous MINLP model for the design of distillation-pervaporation systems • The synthesis task • is to determine: • Nth of the column • feed tray position • reflux ratio • membrane structure • reflux scheme Rigorous modelling: Dist. Column: 1 bar, MESH equations, tray by tray, Margules activity coeff. for the liquid phase, ideal vapour phase, latent heat enthalpy Membrane unit: transport calculation is based on experimental data 1/3 m2 flat membranes, costing - industrial practice Adequate costing equations, utility prices

38. Superstructure 1/3 m2 flat PVA membranes in blocks The blocks (or modules) can be connected in both series or parallel Distillation column superstructure: Viswanathan & Grossmann (1993) Membrane superstructure: new Multiple level optimisation (successive refinement) enables reducing the number of binary model variables Modelling of the membranes is based on experimental data

39. Industrial example Optimised Base case 12% savings in the TAC Other calculations using the MINLP model Ethanol yield - TAC Membrane surface - TAC

40. III. Rigorous MINLP model for the design of wastewater strippers Wastewater cleaning by stripping Minor quantities of acetone, methanol, and ethanol in water Superstructure Similar to the distillation column superstructure of Viswanathan & Grossmann (1993) VLE calculation Wilson binary interactions Ideal vapour phase Theoretical stages 1 bar Latent heat enthalpy Antoine vapour pressure

41. Conclusions: • Complex evaluation of distillation based heat integrated separation schemes is presented. Beside the heat integration the new sloppy structures proved to be competitive. • New, fairly linear, MINLP modell for MENS is developed and succesfully tested for literature examples and industrial case studies. Thank you for your attention.

42. Utility prices

43. Controllability investigations,design • interactive and challenging part of process design or development. Control structure synthesis • control targets are defined, • the sets of controlled variables and possible manipulated variables are determined (degrees of freedom) • pairing of the controlled and manipulated variables: steady state control indices, dynamic behaviours in the cases of open and closed control loops of the promising control structures.

44. Demonstration of interaction between design and control • comprehensive design of five energy integrated separation schemes • three-component-alcohol-mixture is separated in five distillation based energy integrated two-column separation systems: • two heat integrated distillation schemes • fully thermally coupled distillation column (Petlyuk, Kaibel) • sloppy separation sequences

45. Detailed results of economic studies

46. Estimation of capital cost Douglas, J. M., Conceptual design of chemical processes, McGraw-Hill Book Company Marshall & Swift index: 1056.8/280 Project life: 10years Major sizes are estimated by HYSYS flowsheet simulator (Feed: 100 kmol/h)

47. Petlyuk column, open loop, feed composition

48. Heat integrated (DQB) column, open loop, feed composition

49. Petlyuk (dividing wall) column, closed loop (L-S-B), feed composition

50. Heat integrated (DQB) column, closed loop (D-L-B), feed composition