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Ideality of a CSTR

Ideality of a CSTR. Jordan H. Nelson. Brief Overview. Introduction – General CSTR Information. Three Questions. Experimental Conclusions. Schematic of the CSTR. Where is the best mixing in the CSTR ? What is τ mean and how does it compare to τ ideal ?

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Ideality of a CSTR

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  1. Ideality of a CSTR Jordan H. Nelson Property of Beehive Engineering

  2. Brief Overview Introduction – General CSTR Information Three Questions Experimental Conclusions Property of Beehive Engineering

  3. Schematic of the CSTR Property of Beehive Engineering

  4. Where is the best mixing in the CSTR? What is τmean and how does it compare to τideal? What configuration of PFR-CSTR will produce the greatest conversion? 3 Questions ? Property of Beehive Engineering

  5. Impeller selection Food Dye Test Dead Zones Impeller Speed Where is the Best Mixing? Property of Beehive Engineering

  6. Flow Patterns of different impellers Rushton Impeller Marine Impeller Property of Beehive Engineering

  7. τMean – Measured mean residence time The amount of time a molecule spends in the reactor τIdeal – Ideal residence time is calculated from the following equation τMean vs τIdeal? Property of Beehive Engineering

  8. Fill reactor with low concentration salt (baseline) Spike reactor at most ideal mixing Create spike concentration at least one order of magnitude larger than baseline Measure change in conductivity over time Run experiment at different impeller speeds Experiment Property of Beehive Engineering

  9. Yikes! Plot of Concentration vs Time with Error Property of Beehive Engineering

  10. Measured Concentration over time in the CSTR. Property of Beehive Engineering

  11. Measured concentrations are used to create the residence time distribution function RTD Function E(t) Property of Beehive Engineering

  12. Plot of an ideal residence time distribution function Property of Beehive Engineering

  13. Residence time distributions Property of Beehive Engineering

  14. Using E(t) the following equations produce the mean residence time Mean Residence Time Property of Beehive Engineering

  15. Comparison of Residence Times Property of Beehive Engineering

  16. Over an hour of data was lost from Opto 22 Calculation of Reynolds number over 4000 (Turbulent) Equation applies to a baffled CSTR RPM speed of 300 obtained full turbulence Loss of Data Property of Beehive Engineering

  17. Schematic of arrangements Levenspiel Plot Conduct saponification reaction in the reactor at different RPM’s Use Equimolar flow rates and concentrations of reactants Quench reaction with a HCl and titrate with NaOH CSTR-PFR Configurations ? Property of Beehive Engineering

  18. Series Reactor with CSTR Before PFR. Property of Beehive Engineering

  19. Series Reactor with PFR Before CSTR. Property of Beehive Engineering

  20. Property of Beehive Engineering

  21. Schematic of arrangements Levenspiel Plot Conduct saponification reaction in the reactor at different RPM’s Use Equimolar flow rates and concentrations of reactants Quench reaction with a HCl and titrate with NaOH CSTR-PFR Configurations ? Property of Beehive Engineering

  22. Measured Conversion for PFR-CSTR Configuration Property of Beehive Engineering

  23. Measured Conversion for CSTR-PFR Configuration Property of Beehive Engineering

  24. Where is the best mixing in the CSTR? What is τmean and how does it compare to τideal? What configuration of PFR-CSTR will produce the greatest conversion? 3 Questions ? Property of Beehive Engineering

  25. Better mixing for a Rushton impeller is below the impeller The reactor is far from ideal at low impeller speeds The PFR-CSTR arrangement provided better conversions Run the PFR-CSTR reactor at RPM’s of higher than 300 Conclusions Property of Beehive Engineering

  26. Run the experiment again to obtain the lost residence time values Run the saponification reaction at higher temperatures Exit sampling stream should be at the bottom of the reactor Opportunities Property of Beehive Engineering

  27. Taryn Herrera Robert Bohman Michael Vanderhooft Dr. Francis V. Hanson Dr. Misha Skliar Acknowledgements Property of Beehive Engineering

  28. REFERENCES De Nevers, Noel, Fluid Mechanics, McGraw Hill, New York N.Y. (2005) Fogler, H. Scott, Elements of Chemical Reaction Engineering, Prentice Hall, Upper Saddle River, N.J. (1999) Havorka, R.B., and Kendall H.B. “Tubular Reactor at Low Flow Rates.” Chemical Engineering Progress, Vol. 56. No. 8 (1960). Ring, Terry A, Choi, Byung S., Wan, Bin., Phyliw, Susan., and Dhanasekharan, Kumar. “Residence Time Distributions in a Stirred Tank-Comparison of CFD Predictions with Experiments.” Industrial and Engineering Chemistry. (2003). Ring, Terry A, Choi, Byung S., Wan, Bin., Phyliw, Susan., and Dhanasekharan, Kumar. “Predicting Residence Time Distribution using Fluent” Fluent Magazine. (2003). Property of Beehive Engineering

  29. What to expect from your CSTR. Property of Beehive Engineering

  30. Question? Property of Beehive Engineering

  31. Design Equations Property of Beehive Engineering

  32. Design Equations Property of Beehive Engineering

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