1 / 15

Separation of Ternary Heteroazeotropic Mixtures in a Closed Multivessel Batch Distillation Column

N T N U. International Conference on Distillation & Absorption 30 September - 2 October 2002, Baden - Baden, Germany. Separation of Ternary Heteroazeotropic Mixtures in a Closed Multivessel Batch Distillation Column. Stathis Skouras and Sigurd Skogestad. N T N U.

mollie-duran
Download Presentation

Separation of Ternary Heteroazeotropic Mixtures in a Closed Multivessel Batch Distillation Column

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. N T N U International Conference on Distillation & Absorption 30 September - 2 October 2002, Baden - Baden, Germany Separation of Ternary Heteroazeotropic Mixtures in a Closed Multivessel Batch Distillation Column Stathis Skouras and Sigurd Skogestad

  2. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden Presentation Outline • Project objective • The multivessel batch column • The model • Simulation results • System 1: Serafimov’s topological class 1.0-2 • System 2: Serafimov’s topological class 1.0-1a • Discussion • Conclusions • Future plans

  3. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden Project Objective • Is it feasible to separate heteroazeotropic mixtures in the closed multivessel batch column? • What kind of heteroazeotropes can be separated in the novel column?

  4. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden The Multivessel Batch Column Characteristics: • Batch column • 2 sections and 3 vessels • Closed (total reflux) operation • Vapor bypass configuration • Indirect level control in the vessels with TCs Why multivessel column? • Simple to operate. No off-cut fractions. Column ‘runs by itself’ • Ternary mixtures separated simultaneously in one closed operation. Final products accumulated in the 3 vessels • Energy (time) savings due to the multieffect nature of the operation.

  5. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden The Model • Staged column model, 25 stages in each section • No vapor holdup - constant liquid holdup • Constant vapor flows - liquid flows from the T-controllers • Perfect mixing and equilibrium at all stages • Ideal vapor phase • VLE from UNIQUAC • LLE from experimental data • Atmospheric pressure P = 1.013 bar • Simulations performed in MATLAB

  6. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden System 1:Serafimov’s topological class 1.0-2 DISTILLATION LINES MAP • One binary heteroazeotrope • One distillation boundary (unstable separatrix) • Two distillation regions • Final products in the vessels depend on the feed The problem Not all 3 original components can be recovered by simple distillation The idea The boundary is crossed by decantation and all 3 original components are recovered in a distillation-decanter hybrid

  7. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden Simulations Step 1: Built up the composition profile • FeedF in the left feed region • Methanol in the top (unstable node) • Heteroazeotrope in the middle (saddle) • 1-Butanol in the bottom vessel (stable node)

  8. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden Simulations Step 2: Decant-Reflux the organic phase • Decanter at the middle of the column (internal) • Split the heteroazeotrope in the decanter • Reflux the organic phase in the column • Direct level control in the decanter

  9. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden System 2: Serafimov’s topological class 1.0-1a DISTILLATION LINES MAP • One binary heteroazeotrope • No distillation boundary • Final products in the vessels depend on the feed The problem Separation stops because of the heteroazotrope accumulation in the top The idea The liquid-liquid split is used to overcome the azeotropic composition, thus enhancing the separation of the original mixture

  10. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden Simulations Step 1: Built-up the composition profile • Feed F in the upper feed region • Heteroazeotrope in the top (unstable node) • Ethyl Acetate (EtAc) in the middle (saddle) • Acetic Acid (AcAc) in the bottom (stable node)

  11. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden Simulations Step 2: Decant-Reflux the organic phase • Decanter at the top of the column • Split the heteroazeotrope in the decanter • Reflux the organic phase in the column • Direct level control in the decanter

  12. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden Discussion • A combination of the closed multivessel batch column with a decanter was proposed for the separation of ternary heteroazeotropes • Separation of two classes of heteroazeotropes was studied. Both of them can be separated in the novel column • The decanter can be placed either in the middle (internal) or in the top of the column, according to the nature (class) of the mixture • Part of the separation is accomplished by distillation, while the liquid-liquid split in the decanter is used for crossing the distillation boundary and overcoming the azeotropic composition • Final products accumulated in the vessels at the end of the process • The novel process is simple, there is no need for off-cut fractions and the column runs almost ‘by itself’

  13. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden Conclusions • Separation of heteroazeotropic mixtures is feasible in a closed multivessel batch distillation decanter hybrid • Systems belonging to Serafimov’s topological classes 1.0-2 and 1.0-1a can be separated in the proposed novel process

  14. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden Future Plans • Which other azeotropic classes can be separated in the proposed column? • System Water-Acetic Acid-Butyl Acetate belongs to Serafimov’s class 1.0-1b. Can it be separated? • Experimental verification of our simulation results • Energy (time) savings of the proposed process compared to conventional batch configurations e.g. batch rectifier?

  15. N T N U International Conference on Distillation & Absorption 2002, Baden-Baden Serafimov’s classification • Serafimov’s work back in the late 60’s in USSR • 26 classes of feasible topological structures of VLE diagrams • Results presented again in 1996: • Serafimov, L.A., (1996). “Thermodynamic and Topological Analysis of Liquid-Vapor Phase Equilibrium Diagram and Problems of Rectification of Multicomponent Mixtures”, Book: Mathematical Methods in Contemporary Chemistry, S.I. Kuchanov (Ed.) Gordon and breach Publishers, Amsterdam, 557-605 • More material: • PhD thesis (2000) by E. K. Hilmen., Chapter 3 • Available at: www.chembio.ntnu.no/users/skoge/publications/thesis/2000/hilmen

More Related