1. CSTR Ideality November 29, 2006 By Taryn Herrera

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

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

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

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

6. Figure 1 Schematic Diagram for CSTR ItemDescription 1Mixing Point 2 3 4Mixing Points 5 Water Bath Inlet and Outlet 6 Four Wall Mounted Baffles 7Mixer Drive 8Marine Type Impeller 9CSTR Vessel 10Water Bath Vessel The CSTR Apparatus

7. Characterization of Ideality Ideal Residence Time vs. Mean Residence Time Ideal Residence Time vs. Mean Residence Time Residence Time is how long material stays in reactor Residence Time is how long material stays in reactor Comparison is done numerically and graphically 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 E(t) or RTD, measures fraction of material in reactor between two times t m, mean residence time t m, mean residence time Sigma or variance, measures the distribution’s spread 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.)

15. RPM Mean Residence TimeStandard DeviationSigmaSigma/Tau 15357.5711.58206.870.58 30358.1411.58206.350.58 Ideal CSTR466.975.90

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

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

18. CSTR Non-Ideality Rushton ImpellerMarine Impeller

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

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

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

22. Questions?