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MCF Development RTD
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Plug flow, laminar flow MCF! Radial dispersion through molecular diffusion](https://image.slidesharecdn.com/crystal-flow-processing-1-2014-140524060427-phpapp02/75/Flow-Crystallisation-and-Continuous-Processing-35-2048.jpg)
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Flow, Crystallisation and Continuous Processing
- 1. 1 Crystallisation, Flow andContinuous Processing. By Professor Malcolm Mackley Department of Chemical Engineering and Biotechnology. University of Cambridge UK Strathclyde 2014 A story that started for me in 1970
- 2. 2 Crystallisation Flow Nucleation Growth Morphology Supersaturation Pressure SupercoolingStirring Simple shear flow Extensional flow Complex flows Driving forces Key factors Flow induced crystallisation depends on all of the above
- 3. 3 Types of Flow Laminaror Complex flow Go with the flow! where = density u = velocity D = a length scale h = viscosity Re < 1 𝐿𝑎𝑚𝑖𝑛𝑎𝑟 𝑅𝑒 ≈ 1 − 1000 𝐶𝑜𝑚𝑝𝑙𝑒𝑥 𝑅𝑒 > 1000 𝑇𝑢𝑟𝑏𝑢𝑙𝑒𝑛𝑡 Reynolds number Re = 𝜌 𝑢 𝐷 𝜂
- 4. 4 Types of Flow1 Simple shear (laminar) Simple shear is not so simple because the flow contains a rotational component Couette Viscometer Strain rate 𝛾 = 𝑑𝑢 𝑑𝑦 Velocity u Distance y
- 5. 5 Types of Flow2 Extensional flow (laminar) Pure extensional flows are not easy to generate in the laboratory Extension rate 𝜖 = 𝑑𝑢 𝑑𝑥 Velocity u Distance x Opposed jets
- 6. 6 Types of Flow3 Complex Flows. Time dependant combinations of simple shear and extensional flow. Taylor Couette Flow Turbulence Stirred vessels Oscillatory Flow Mixing (OFM) “turbulent” flows are a complex time dependant combinations of simple shear and extensional; flow
- 7. 7 Solution Crystallisation ofPolyethylene (PE) Polyethylene is chemically the simplist polymer and also the worlds largest tonnage polymer “Polymer Single crystals” Sir Charles Frank Prof Andrew Keller 0.1% PE/Xylene @ 110 0 C 24 hrs @ 80 0 C
- 8. 8 Solution Crystallisation ofPolyethylene (PE) The structure and morphology of Polyethylene crystals is a work of art “Perfect Single Crystals” Self seeding of PE crystals; uniform size 110 0 C 24 hrs @ 80 0 C 4 0 C/hr to 100 0 C 24 hrs @ 80 0 C D.C.Bassett (1960s)
- 9. 9 Flow induced PEsolution crystallisation Simple shear, no chain stretching but Extensional Flows stretch’s chains Simple shear Couette flow. No crystallisation Taylor vortex Couette flow. Fibrous crystallisation
- 10. 10 Flow induced PEsolution crystallisation Shish Kebabs are “tasty”; a combination of extended and folded chain crystals Shish Kebab Fibrous crystals
- 11. 11 Flow induced PEsolution crystallisation Millions of PE polymer chains ordered to form beautiful structures No Flow With flow Chain folded Single crystals Shish kebab Fibrous crystals
- 12. 1. Can enhancecrystal nucleation rates. 2. Can enhance crystal growth rates. 3. Can change crystal morphology. Flow Induced Crystallisation Flow usually influences crystallisation in some sort of way Flow
- 13. Flow Induced Crystallisation Somethings in life are not simple Think • Nucleation conditions (T, P, Composition ) • Growth conditions (T, P, Composition ) • Surface area/ volume ratio. Surface material of vessel and internals. Boundary conditions, heterogenieties • Type of flow • Batch or continuous
- 14. Batch vs ContinuousCrystallisation Batch Continuous • Easy, flexible and universal • Batch number easy • Accepted by legislation authorities • Simple stirrers • Variation between batches • Complex flow • Thermal and shear profiling not easy to control • Scale up is tricky • Not continuous • Continuous! • Thermal, chemical and flow profiling relatively easy Laminar or Complex flow • Scale up easier than batch • Continuous requires front and back end handling • Relatively novel and so acceptance by Companies and legislation more difficult
- 15. Batch Crystallisation No flowMagnetic stirrer Overhead stirrer Stirred vessel crystallisers can be 500 ml – 20 tonnes in size
- 16. Continuous Flow Crystallisation StirredVessels Residence Time Distributions (RTDs) Chemical Engineers “love” RTDs Residence time Fraction of tracer Fraction of tracer Residence time “Plug flow” Continuous Stirred Tank (CST) 𝜏 𝑚 = 𝑚𝑒𝑎𝑛 𝑟𝑒𝑠𝑖𝑑𝑒𝑛𝑐𝑒 𝑡𝑖𝑚𝑒 𝜏 𝑚
- 17. 17 Ways of achieving“plug” flow. • Stirred tanks in series • Turbulent tubular flow • Narrow bore laminar flow • Oscillatory Flow Mixing (OFM) Very long tube v= m/s Chemical Engineers normal choice Long thin tube, less than about 1mm dia “There is more than one way to skin a cat.”
- 18. 18 More ways ofachieving plug flow. • Static mixer tubes • Slug flow in tubes • Taylor Couette flow • Plastic microcapillary film (MCF) Prof Woo-Sik Kim Korea Chemical Engineers like tubes and vessels
- 19. 19 Oscillatory Flow Mixing(OFM) Inertial mixing flow. Tube diameters, mm - cms A question of scale! g/hr, Kg/hr, tonnes/hr “Discovered” in 1980s
- 20. 20 Oscillatory Flow Mixing(OFM) 1980s; process Inventive steps 1979- 1982 Air turbine generates power
- 21. 21Chem Eng Sci1989 Inventive steps. Plug flow residence time
- 22. 22 Heat transfer ChenEng Sci
- 23. 23 Mass transfer ChengEng Sci
- 24. 24 - Oscillator BaseUnit - Feed inlet section - Shell and baffled tube vessels - Product outlet section Development Stage Chem Eng Oscillatory Flow Reactor (OFR) Dr Paul Stonestreet
- 25. 25 Net Flow In NetFlow Out Biodiesel Reaction Progress along Reactor
- 26.
- 27. 27 Further development OFMMeso Reactor Nuno Reis, Minghzi Zheng System configuration Mesotube, diameter d Smoothconstrictions: spacing3d Minimumconstriction diameter 0.4d 2000s 45º 35 mm, V 4.5 mL 45º 35 mm, V 4.5 mL a) b) L d d0
- 28. 28 0 100 200300 400 500 600 700 800 900 0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02 Time (s) E(t)(-) b) Exp-E(t)1 Exp-E(t)2 Exp-E(t)3 Fit-E(t)2 (1->2) Fit-E(t)3 (1->3) Fit-E(t) 3 (2->3) Continuous Flow Oscillatory Mesoreactor Minghzi Zheng Plug flow meso reactor
- 29. 29 Corrugated Flourinated (FEP)plastic tubing Parker/Texloc Div. of Parflex USA Untried plastic fantastic OFM crystalliser ?
- 30. 30 • Viable flowconfiguration for crystallisation • Long residence times possible • Flow, thermal or concentration profiling possible Oscillatory Flow Mixing (OFM)
- 31. 31 Microcapillary Films (MCFs) “PlasticFantastic” “Discovered” in 1990s
- 32. 32 MicroCapillary Films (MCFs)2000s; invention Die land Polymer flow Quench bath Extrudate to haul off Injector MCF extrudate Bart Hallmark
- 33. 33 T1 T2 T3T4 T5 T6P2 Single screw extruder MCF extrusion die Chilled rollers Spooling Guide rollers Gear pump MCF PLAN VIEW MCF Chill rollers Direction of flow Array of 19 entrainment nozzles Entrainment body Air inlet Polymer melt Die exit Quenching length, L Micro Capillary Film; invention B. Hallmark, et al. Adv. Eng. Mat., (2005).
- 34. 34 MCF Development; PressureDrop 0 2 4 6 8 10 12 14 0 0.2 0.4 0.6 0.8 1 Pressure(bar) Flow rate (mL/min) 25°C 40°C 55°C 70°C 85°C Christian Hornung Polyethylene or FEP
- 35. 35 MCF Development RTD 0 5 10 15 20 25 30 35 40 45 50 05 10 15 20 25 30 t [min] c[mg/l] inlet outlet length = 20 m flow rate = 0.5 ml/min Plug flow, laminar flow MCF! Radial dispersion through molecular diffusion
- 36. MCF Commercialisation 2flat silicon heaters (200 W each) PID control - Temperature monitoring at top and bottom heater plates Tmax = 150 °C developed by Lamina Dielectrics Ltd. & Cambridge University Teflon coated hot plates Temperature control Reactor disk tray Patrick Hestor Lamina Ltd
- 37. MCF Development; Microflow Organic. Kerosene,1.8 mPas Oil, 27 mPas Vegetable oil. 50 mPas Water, 1 mPas, glycerol 10-50 mPas or methanol Video, Methanol into Veg oil Nuno Reis
- 38. MCF Development; Slugseparation Scheiff et al. Lab on a Chip. 2011 Slug separation within capillary flow; something new!
- 39. Bore fluid Nitrogen Gas Cylinder Polymer Solution Die External Coagulant Haul-off Single Capillary, MCFmembranes Air-gap Glass Water Bath MCF Development. Microporous MCF membranes Sina Bonyadi Microporous MCF; something new
- 40. Microporous MCFs 2 µm 100µm 2 µm 1 µm Bonyadi et al. Journal of Membrane Sci 2012
- 41. • Potentially viablegeometry for continuous crystallisation • Narrow bore may cause blockage problems • Optical interrogation possible during flow Microcapillary Films (MCFs)
- 42. 42 • Flow canbe complicated. • Crystallisation can be complicated. • Flow induced crystallisation can be very complicated. • OFM and MCFs can give plug flow processing. Message
- 43.