Clemson University TigerPrints All Theses Theses 12-2011 Chlorine Absorption Utilizing Caustic Sodium Sulfite Henry Mcdonald Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_theses Part of the Chemical Engineering Commons Recommended Citation Mcdonald, Henry, "Chlorine Absorption Utilizing Caustic Sodium Sulfite" (2011). All Theses. 1274. https://tigerprints.clemson.edu/all_theses/1274 This Thesis is brought to you for free and open access by the Theses at TigerPrints. It has been accepted for inclusion in All Theses by an authorized administrator of TigerPrints. For more information, please contact [email protected]. CHLORINE ABSORPTION UTILIZING CAUSTIC SODIUM SULFITE A Thesis Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Master of Science Chemical Engineering by Henry Evan McDonald December 2011 Accepted by: Dr. Charles Gooding, Committee Chair Dr. Scott Husson Dr. David Bruce i ABSTRACT A scrubber was required to abate a waste stream containing chlorine gas created in the electrolytic dissolution step of the aqueous polishing process at the Mixed Oxides Fuel Fabrication Facility at Savannah River Site, South Carolina. A method of absorption that utilized caustic sodium sulfite as the scrubbing agent was studied for implementation in the process. This method was found to be highly efficient with respect to process requirements, and it was also found to provide enhanced performance over the more conventional method of chlorine scrubbing which uses only aqueous sodium hydroxide as a reagent. Sulfite provides an additional advantage in that it scavenges other potential pollutants such as hypochlorite and prevents their desorption back into the gas stream. Absorption was found to be rate-limited by liquid phase mass transfer at low to medium sulfite concentrations. The process is believed to be rate-limited by gas phase mass transfer at higher sulfite concentrations, although specific conditions for gas phase control could not be determined. A significant amount of the sulfite was found to be consumed by an undesirable oxidation side reaction. The process was found to be mildly exothermic, but heat effects were not detrimental to system performance. ii DEDICATION The author would like to dedicate this work to his parents, Dr. and Mrs. Timothy and Deborah McDonald. iii ACKNOWLEDGMENTS Thanks to the U.S. Department of Energy for funding this research. The author would like to express his sincere gratitude to his advisor, Dr. Charles Gooding, for his guidance, support, and hard work on this project. Very special thanks also to the other members of the committee, Dr. Scott Husson and Dr. David Bruce, for their help and their many excellent suggestions for improvements. This work was carried out at the Clemson Engineering Technologies Laboratory. Thanks go out to all the staff there, but particularly to John Harden and Steve Hoeffner. Without their guidance the author would have been hopelessly lost, and it was a true pleasure to work with them. Thanks also to Jamie Kearns, Michael McCulley, and Will Vining, who contributed much helpful insight during the early stages of this project. Lastly the author would like to thank his family for their love, support, and ever-amusing companionship. iv TABLE OF CONTENTS Page TITLE PAGE .................................................................................................................... i ABSTRACT ..................................................................................................................... ii DEDICATION ................................................................................................................ iii ACKNOWLEDGMENTS .............................................................................................. iv LIST OF TABLES ......................................................................................................... vii LIST OF FIGURES ........................................................................................................ ix CHAPTER I. ORIGIN AND SCOPE .................................................................................. 1 II. LITERATURE REVIEW .............................................................................. 3 Reactions involving Chlorine and Aqueous Sodium Hydroxide ............. 3 Reactions involving Chlorine and Sulfite ................................................ 8 Aqueous Chemistry of Sulfite ................................................................ 12 Summary of Relevant Reaction Pathways ............................................. 13 Mass Transfer......................................................................................... 15 Heat Effects ............................................................................................ 19 III. EXPERIMENTAL METHOD ..................................................................... 20 General Method ..................................................................................... 20 Terminology ........................................................................................... 20 Apparatus ............................................................................................... 21 Experimental Procedure ......................................................................... 27 IV. EXPERIMENTAL RESULTS..................................................................... 30 Analysis of Scrubber Performance ........................................................ 30 Analysis of Chemistry............................................................................ 31 Scrubber Solution Capacity and Effects of Sulfite Concentration......... 43 Mass Transfer......................................................................................... 46 Recirculation Rate .................................................................................. 47 v Inlet Gas Flowrate .................................................................................. 50 Packing Height ....................................................................................... 51 Extended Use/High Salt Concentration ................................................. 54 Role of pH .............................................................................................. 57 Heat Effects ............................................................................................ 57 Equipment Performance/Additional Safety Concerns ........................... 58 V. CONCLUSIONS.......................................................................................... 60 APPENDICES ............................................................................................................... 62 A: Selected Experimental Data ......................................................................... 63 B: Sample Calculations..................................................................................... 72 C: Calculation and Interpretation of Chromatography Data............................. 74 D: List of Chemical Reactions with Kinetic and Equilibrium Data ................. 77 E: List of Physical Constants and other Notable Information .......................... 78 F: Detailed Experimental Procedure Equipment List ...................................... 79 REFERENCES .............................................................................................................. 83 vi LIST OF TABLES Table Page 2.1 Rate Data for Cl 2 Hydrolysis ......................................................................... 4 2.2 Apparent Equilibrium Constant Data for Cl 2 Hydrolysis .............................. 4 2.3 Rate Constants for Forward Reaction of Cl 2 with Hydroxide ....................... 5 2.4 Rate Constants for Dissociation of Hypochlorous Acid ................................ 7 2.5 Equilibrium Constants for Dissociation of Hypochlorous Acid .................... 7 2.6 Rate Constants for the Empirical Rate Law ................................................... 9 2.7 Values of Rate Constants Used in Eq. 16 .................................................... 10 2.8 Rate Constants for Formation of Chlorosulfite Intermediate and Hydrolysis .................................................................. 11 2.9 Rate Constants for Selected Species Reactions with Sulfite ....................... 11 3.1 Notable Characteristics of Mellapak 750-Y ................................................ 26 4.1 Experimental Results of 0.1 M Sulfite Concentration Run ......................... 31 4.2 Average Moles of Reagent Consumed per Mole Cl 2 Scrubbed. ................ 39 4.3 Effluent Cl 2 Concentrations for the Half Sulfite Run .................................. 44 4.4 Effluent Cl 2 Concentrations for the Double Packing Height ....................... 44 4.5.1 Recirculation Rate Analysis for 81 m 3/m 2 hr Liquid Loading ..................... 48 4.5.2 Recirculation Rate Analysis for 54 m 3/m 2 hr Liquid Loading ..................... 48 4.5.3 Recirculation Rate Analysis for 27 m 3/m 2 hr Liquid Loading ..................... 49 4.6 Inlet Air Flowrate Analysis Table 1 ............................................................. 50 4.7 Inlet Air Flowrate Analysis Table 2 ............................................................. 51 vii List of Tables (Continued) Table Page 4.8 Packing Height Analysis: Effluent Concentrations for Double Packing Height Run .................................................................