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Partial Separation of an Azeotropic Mixture of Hydrogen Chloride and Water and Copper (II) Chloride Recovery for Optimization of the Copper-Chlorine Cycle

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Partial Separation of an Azeotropic Mixture of Hydrogen Chloride and Water and Copper (II) Chloride Recovery for Optimization of the Copper-Chlorine Cycle Partial Separation of an Azeotropic Mixture of Hydrogen Chloride and Water and Copper (II) Chloride Recovery for Optimization of the Copper-Chlorine Cycle by Matthew P. Lescisin A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Applied Science in The Faculty of Engineering and Applied Science Mechanical Engineering University of Ontario Institute of Technology September 2017 © Matthew P. Lescisin, 2017 Contents Contents ii Abstract v Acknowledgments vi List of Figures vii List of Tables viii Nomenclature ix Quantities...................................... ix Greek Letters.................................... x Subscripts...................................... xi Acronyms...................................... xi 1 Introduction1 2 Background4 2.1 Boiling in the Subcooled Liquid Region .................. 4 2.2 Vapor-Liquid Equilibrium (VLE)...................... 5 2.3 Phase Diagrams................................ 5 2.3.1 Tie-Lines ............................... 6 2.4 Distillation .................................. 6 2.5 Azeotropes .................................. 8 3 Literature Review9 3.1 Azeotropic Distillation............................ 9 3.2 Extractive Distillation............................ 10 3.3 Pressure-Swing Distillation .......................... 11 3.4 Batch Mode.................................. 13 3.5 Heat-Integrated Distillation Columns.................... 13 3.5.1 Heat-Integrated PSD......................... 14 ii CONTENTS iii 3.6 Reflux Ratio ................................. 15 3.7 HETP Correlations.............................. 15 3.8 Outcome of the Literature Review ..................... 15 4 The Effect of Metastability on Crystallization 17 4.1 Crystallization Results and Discussion................... 18 4.2 Metastability ................................. 18 4.2.1 Metastability Experimental Method ................ 20 4.2.2 Formulation of Metastability & Equilibrium............ 20 4.2.3 Metastability Results and Discussion................. 21 4.2.4 Metastability Conclusions...................... 25 5 Distillation Simulation 26 5.1 Thermodynamic Models........................... 26 5.2 Simulation Setup................................ 27 5.3 Simulation Results.............................. 28 5.3.1 Pressure-Swing Distillation ..................... 28 5.3.2 Single-Column Distillation...................... 34 5.4 Simulation Conclusion............................ 34 6 Apparatus Design 36 6.1 Column Pressure................................ 37 6.2 Experimental Setup Components....................... 37 6.2.1 Estimation of Mass Loss due to Corrosion............. 38 6.3 Output Analysis ............................... 39 6.3.1 Non-Applicability of Raoult’s Law................. 40 6.3.2 Determining xHCl ........................... 40 7 Column Geometry 42 7.1 Number of Stages............................... 42 7.2 Column Height................................ 43 7.2.1 Method of Transfer Units...................... 43 7.2.2 Empirical Correlations........................ 45 7.3 Column Diameter............................... 48 7.4 Location of Feed Stage............................ 48 8 Measurement and Control 50 8.1 Temperature Measurement ......................... 50 8.2 Column Heating ................................ 51 8.3 Control System................................. 51 8.3.1 Schmitt Trigger............................. 51 8.3.2 PID Control ............................. 52 iv CONTENTS 8.3.3 Electrical Design........................... 56 9 Apparatus Operation 58 9.1 Experimental Procedure........................... 58 10 Distillation Experimental Results and Discussion 60 10.1 Analysis of the Column Outputs ...................... 60 10.1.1 Comparison of Experimental Results and Simulation Results . 62 10.2 Weaknesses & Limitations in the Results.................. 62 10.2.1 Corrosion Product.......................... 62 10.2.2 Vapour Pressure of the Vapour Phase ............... 62 10.3 Uncertainty Analysis............................. 64 10.3.1 Systematic Error........................... 64 10.3.2 Random Error ............................ 64 10.3.3 Method of Kline & McClintock................... 65 10.4 Distillation Conclusions and Recommendations.............. 66 11 Conclusions and Recommendations 68 References 70 Appendix A Scripts 76 A.1 McCabe-Thiele Method ........................... 76 A.2 Method of Kline & McClintock....................... 80 Appendix B Crystallization Results 86 Abstract An atmospheric-pressure distillation system is designed and constructed to partially separate hydrochloric acid and water. The system concentrates HCl(aq) between the electrolyzer and hydrolysis steps of the Copper-Chlorine (Cu-Cl) cycle. Thus, the system partially recycles HCl(aq), thereby decreasing the total operating cost of the cycle. The separation is only partial, as the mixture is unable to cross the azeotrope with only a single pressure. The distillation system consists primarily of one packed distillation column, which employs heating tapes and thermocouples to achieve a desired axial temperature profile. The column can be operated in batch or continuous mode. After performing physical distillation experiments, it is found that feeds less than azeotropic concentration are separated into H2O(l) and highly-concentrated HCl(aq) (albeit at less than azeotropic concentration). Feeds greater than azeotropic concentration are not investigated as they are extremely corrosive (rich in HCl) and would likely destroy the apparatus. Corrosion product is prevalent in the bottoms product; it is a source of error that is partially mitigated by filtration. No correlation is found between feed concentration and output concentration. That is, the distillate is H2O(l) and the bottoms is HCl(aq) near azeotropic concentration; as long as the feed concentration is any value less than azeotropic. In other words, the degree of separation is found to be independent of the feed concentration, for feed concentrations less than azeotropic. The bottoms concentration varies from experiment to experiment, but does so randomly, likely the result of corrosion impurities affecting the calculation of its concentration. A simulation of pressure-swing distillation (PSD) is also performed to help determine the feasibility of HCl-H2O separation and the degree of separation. Furthermore, an investigation into metastability and its effect on the crystallization of CuCl2 from HCl(aq) solutions is presented in Chapter4. v Acknowledgments Dr. K. Pope, Dr. M. A. Rosen and Dr. O. A. Jianu are very gratefully acknowledged for their advice and guidance throughout this project. The financial assistance of the Natural Sciences and Engineering Research Council of Canada (NSERC), Ontario Research Fund (ORF) and Canadian Nuclear Laboratories (CNL) is gratefully acknowledged. vi List of Figures 1.1 Schematic of the Cu-Cl cycle [2] ...................... 2 2.1 Example Phase Diagram........................... 6 2.2 Distillation Example.............................. 7 3.1 Azeotropic Distillation Example [7]..................... 10 4.1 Hysteresis Loop of Metastability ...................... 19 4.2 Experimental Data on MSZW of CuCl2 in H2O.............. 22 4.3 Effect of Cooling Rate on MSZW for CuCl2 in H2O ........... 23 4.4 Solubility of CuCl2 Dissolving in HCl Solutions of Different Molarities . 24 5.1 COCO (UNIQUAC) Phase Diagram at 1 bar ................ 27 5.2 Chemcad Phase Diagram .......................... 30 5.3 Chemcad Process Flow Diagram ...................... 30 5.4 Simulation Results: Tray Compositions .................. 33 5.5 Chemcad process flow diagram of single column distillation. 34 6.1 Output Chamber Detail........................... 38 6.2 Bottoms including corrosion product..................... 41 7.1 McCabe-Thiele Method ........................... 43 7.2 Equilibrium Concentrations......................... 44 ∗ 7.3 Plot of 1/(yi − yi) vs. y ........................... 44 8.1 Thermocouple locations and temperature zones.............. 50 8.2 Control diagram for n temperature zones ................. 53 8.3 Schmitt trigger flowchart .......................... 53 8.4 PID control flowchart ............................ 54 8.5 Electrical control schematic.......................... 57 vii List of Tables 4.1 Nucleation Order and Nucleation Rate Constants for Several HCl Concen- trations .................................... 22 4.2 Nucleation Order and Rate for CuCl2 in H2O-HCl............ 23 5.1 Simulation Results: Stream Compositions................. 28 5.2 Simulation Results: LPC Distillation Profile................ 29 5.3 Simulation Results: HPC Distillation Profile................. 31 5.4 Simulation Results: LPC Tray Composition Data.............. 31 5.5 Simulation Results: HPC Tray Composition Data............. 32 5.6 Single-Column Simulation Results ..................... 34 6.1 Corrosion Resistance, Data from [41].................... 38 6.2 Parameters for Calculating mlost ...................... 39 7.1 Parameters for Calculating HTU...................... 46 7.2 Parameters used in Equation 7.9 to Calculate DV . 46 7.3 Values used to Calculate Empirical Correlations for HETP......... 47 7.4 Results of Empirical Correlations for HETP................. 47 7.5 Parameters for Calculating Column Diameter............... 49 8.1 Parameters for Calculating Column Heat Input.............. 52 10.1 Measured Densities and Calculated Concentrations............. 61 10.2 Comparison of Experimental Results and Simulation Results
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