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CSTR Ideality

CSTR Ideality. November 29, 2006 By Taryn Herrera. Importance of CSTR Ideality. Economics Design of Reactors Higher Conversion of Reactants. CSTR Ideality. The Experiment The Results Characterization of Ideality Residence Time Distribution Function Causes of CSTR Non-Ideality

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CSTR Ideality

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  1. CSTR Ideality November 29, 2006 By Taryn Herrera

  2. Importance of CSTR Ideality • Economics • Design of Reactors • Higher Conversion of Reactants

  3. CSTR Ideality • The Experiment • The Results • Characterization of Ideality • Residence Time Distribution Function • Causes of CSTR Non-Ideality • Conclusions and Questions

  4. The Experiment • Characterize the ideality of client’s bench CSTR reactor • Operate currently at 30 rpm • Determine most ideal conditions and make recommendations

  5. The Experiment (cont.) • Injection Impulse Step Test • Sodium Chloride is the Tracer • Concentration Measurements by Conductivity • Different Mixer Speeds

  6. The CSTR Apparatus Figure 1 Schematic Diagram for CSTR

  7. Characterization of Ideality • Ideal Residence Time vs. Mean Residence Time • Residence Time is how long material stays in reactor • Comparison is done numerically and graphically

  8. Ideal Residence Time

  9. Residence Time Distribution

  10. Residence Time Distribution (cont.) • E(t) or RTD, measures fraction of material in reactor between two times • tm, mean residence time • Sigma or variance, measures the distribution’s spread

  11. Residence Time Distribution (cont.) Figure 2 Graph from Fluent Magazine showing RTD functions for different methods (Ring, 2004)

  12. The Results

  13. The Results (cont.)

  14. The Results (cont.)

  15. The Results (cont.)

  16. Causes of CSTR Non-Ideality • Poor Mixing • Dead Zones in CSTR • Short Circuit

  17. CSTR Non-Ideality Figure 3 Impulse Injection for CSTR

  18. CSTR Non-Ideality Rushton Impeller Marine Impeller

  19. CSTR Non-Ideality • Turbulent Mixing • Done by Baffles and Mixing Speed • Promotes Better Mixing of Reactants • Dead Zones Minimized • Reynolds Number of 4000

  20. Review • Characterization of Ideality • Residence Time Distribution Function • Mean Residence Time vs. Ideal Residence Time • CSTR Non-Ideality

  21. Conclusions • Use Marine Type Impeller • Promote Turbulence in CSTR • Choose Wisely the Mixing Points and Sampling Points • Use Fluent • Observe other RTD data

  22. Questions?

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