CO 2 Mass Transfer in a Novel Photobioreactor A thesis presented to the faculty of the Russ College of Engineering and Technology of Ohio University In partial fulfillment of the requirements for the degree Master of Science Adam Mielnicki August 2011 © 2011 Adam Mielnicki. All Rights Reserved. 2 This thesis titled CO 2 Mass Transfer in a Novel Photobioreactor by ADAM MIELNICKI has been approved for the Department of Chemical and Biomolecular Engineering and the Russ College of Engineering and Technology by David J. Bayless Loehr Professor of Mechanical Engineering Dennis Irwin Dean, Russ College of Engineering and Technology 3 Abstract MIELNICKI, ADAM, M.S., August 2011, Chemical Engineering CO 2 Mass Transfer in a Novel Photobioreactor Director of Thesis: David J. Bayless A novel carbon capture and storage (CCS) technology at the center of this investigation involves the biosequestration of CO 2 via cyanobacterial photosynthetic processes. A simulated flue gas stream introduces CO 2 into a temperature controlled photobioreactor where cyanobacteria are nourished with a flowing growth solution. Before the microorganism can fix carbon, CO 2 has to dissolve in the liquid growth solution. The absorption of CO 2 presents a potential limiting step in cyanobacterial growth and is therefore in need of quantification. In this study, the effects of growth solution flow rate on the liquid side mass transfer coefficient (k L) were observed and a model was selected for k L prediction. Both the model and experimental data showed that k L tends to increase with flow rate. Gaseous CO 2 concentration was manipulated as well and was shown to affect overall mass transfer but not k L. Higher gaseous CO 2 concentration increased the CO 2 solubility limit, and therefore increased the rate of CO 2 absorption. Approved: _____________________________________________________________ David J. Bayless Loehr Professor of Mechanical Engineering 4 Acknowledgments I would like to sincerely thank my advisor, Dr. David J. Bayless, whose support and guidance has been invaluable in completing this thesis. His extensive engineering knowledge and unique insight on the best course of action have allowed me to overcome research obstacles on numerous occasions. Similarly, this work would not be possible without the help of OCRC faculty and undergraduate members. In particular, I greatly appreciate Jesus Pagan and all his efforts in acquiring the AdeptOne robot. In addition, I would also like to thank the members of my thesis committee, Dr. Michael E. Prudich, Dr. Kevin Crist, and Dr. Morgan L. Vis. for contributing their time and effort towards helping me finish this work. I also want to thank all my friends and colleagues who were always there for me, throughout the good times as well as the bad. Finally, I want to thank my parents, Stanisław and Irena Mielnicki for their love, support, and most of all, having the courage to emigrate from Poland to provide me with more opportunities for success. 5 TABLE OF CONTENTS Page Abstract ............................................................................................................................................ 3 Acknowledgments ............................................................................................................................ 4 List of Tables ..................................................................................................................................... 8 List of Figures ................................................................................................................................... 9 Chapter 1 - Introduction ................................................................................................................. 12 1.1 Background .......................................................................................................................... 12 1.1.1 CO 2 Sequestration Methods ......................................................................................... 12 1.2 Biosequestration .................................................................................................................. 13 1.2.1 Photobioreactor Overview ........................................................................................... 13 1.2.2 Obstacles to Commercialization ................................................................................... 14 1.2.3 Optimizing CO 2 Mass Transfer Rate ............................................................................. 14 1.3 Objectives ............................................................................................................................ 15 Chapter 2 - Literature Review ........................................................................................................ 17 2.1 Falling Film Mass Transfer Models ...................................................................................... 17 2.1.1 Falling Film Flow ........................................................................................................... 17 2.1.2 Hypothetical Models .................................................................................................... 18 2.1.3 Empirical Models .......................................................................................................... 21 2.2 Film Depth Measurement Methods .................................................................................... 23 2.2.1 Introduction .................................................................................................................. 23 2.2.2 Needle Contact ............................................................................................................. 23 2.2.3 Drainage ....................................................................................................................... 25 2.2.4 Hot-wire Anemometry ................................................................................................. 25 2.2.5 Optical .......................................................................................................................... 25 2.2.6 Capacitance .................................................................................................................. 26 2.2.7 Parallel-Wire Conductance ........................................................................................... 26 Chapter 3 - Laboratory Equipment................................................................................................. 28 3.1 TOC Analyzer ........................................................................................................................ 28 3.1.1 Introduction and Sample Consideration ...................................................................... 28 6 Page 3.1.2 Inorganic Carbon Measurement .................................................................................. 28 3.1.3 Contamination Precautions .......................................................................................... 30 3.1.4 Analyzer Calibration ..................................................................................................... 31 3.2 CRF-II .................................................................................................................................... 32 3.2.1 Scope of Description ..................................................................................................... 32 3.2.2 Reaction Chamber and Flow......................................................................................... 32 3.2.3 Gaseous Composition ................................................................................................... 35 3.2.4 Temperature ................................................................................................................. 36 3.2.5 Light .............................................................................................................................. 36 3.3 Safety ................................................................................................................................... 36 3.3.1 TOC Analyzer ................................................................................................................ 36 3.3.2 CRF-II ............................................................................................................................. 37 Chapter 4 - Results and Discussion ................................................................................................ 38 4.1 Review of Objectives ........................................................................................................... 38 4.2 Film Thickness Measurement .............................................................................................. 38 4.2.1 Offline Rig Design ......................................................................................................... 39 4.2.2 Parallel-Wire Conductance Probe Calibration .............................................................. 47 4.2.3 Calibration Considerations ........................................................................................... 50 4.2.4 Data Collection Method for Film Thickness Measurements ........................................ 57 4.2.5 Determination of Testing Conditions ........................................................................... 61 4.2.6 Film Thickness Data ...................................................................................................... 66 4.3 Experimental Mass Transfer ...............................................................................................