View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Texas A&M Repository BINARY MIXTURE FLAMMABILITY CHARACTERISTICS FOR HAZARD ASSESSMENT A Dissertation by MIGVIA DEL C. VIDAL VÁZQUEZ Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY August 2005 Major Subject: Chemical Engineering BINARY MIXTURE FLAMMABILITY CHARACTERISTICS FOR HAZARD ASSESSMENT A Dissertation by MIGVIA DEL C. VIDAL VÁZQUEZ Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved by: Chair of Committee, M. Sam Mannan Committee Members, James C. Holste Kenneth R. Hall Jerald Caton Head of Department, Kenneth R. Hall August 2005 Major Subject: Chemical Engineering iii ABSTRACT Binary Mixture Flammability Characteristics for Hazard Assessment. (August 2005) Migvia del C. Vidal Vázquez, B.S., Universidad de Puerto Rico, Mayagüez, PR Chair of Advisory Committee: Dr. M. Sam Mannan Flammability is an important factor of safe practices for handling and storage of liquid mixtures and for the evaluation of the precise level of risk. Flash point is a major property used to determine the fire and explosion hazards of a liquid, and it is defined as the minimum temperature at which the vapor present over the liquid at equilibrium forms a flammable mixture when mixed with air. Experimental tests for the complete composition range of a mixture are time consuming, whereas a mixture flash point can be estimated using a computational method and available information. The information needed for mixture flash point predictions are flashpoints, vapor pressures, and activity coefficients as functions of temperature for each mixture component. Generally, sufficient experimental data are unavailable and other ways of determining the basic information are needed. A procedure to evaluate the flash point of binary mixtures is proposed, which provides techniques that can be used to estimate a parameter that is needed for binary mixture flash point evaluations. Minimum flash point behavior (MFPB) is exhibited when the flash point of the mixture is below the flash points of the individual components of the mixture. The identification of this behavior is critical, because a hazardous situation results from taking the lowest component flash point value as the mixture flash point. Flash point predictions were performed for 14 binary mixtures using various Gex models for the activity coefficients. Quantum chemical calculations and UNIFAC, a theoretical model that does not require experimental binary interaction parameters, are iv employed in the mixture flash point predictions, which are validated with experimental data. MFPB is successfully predicted using the UNIFAC model when there are insufficient vapor liquid data. The identification of inherent safety principles that can be applied to the flammability of binary liquid mixtures is also studied. The effect on the flash point values of three binary mixtures in which octane is the solute is investigated to apply the inherent safety concept. v DEDICATION To my parents Mr. Miguel A. Vidal Maldonado and Mrs. Sylvia E. Vázquez Cordero and my brother and sister Mr. Miguel A. Vidal Vázquez and Mrs. Marieberta Vidal Vázquez vi ACKNOWLEDGEMENTS This work would not have been possible without the contribution of many people. Usually great outcomes come when great minds and people work together and the completion of this work is no exception. This is the product of an excellent team work. I would like to give thanks to my advisor and mentor Dr. M. Sam Mannan for all his support, friendship and more than anything for his faith in me. I have definitely learned a lot about process safety, professionalism and team work with you. I will always remember your advice at the beginning of each research group meeting and your satisfaction when you finally learned how to say my entire name. It was definitely a big accomplishment for you because since that day you have always called me by my two last names and have told everyone the story behind my name. I definitely owe a BIG thanks to Dr. William J. Rogers for all his technical discussions and grammatical help. The importance that you give to every single detail made possible my participation in many AIChE conferences and the publication of every paper that came out as a product of this work. Thanks a lot for your disposition, assistance and for your passion in delivering a high quality product. I want to express my appreciation to my committee members James C. Holste, Kenneth R. Hall and Jerald Caton for their cooperation and for serving as committee members. Also, I am totally grateful to the MKOPSC and Chemical Engineering Department staff for making this journey a lot easier. I also want to thank the Advanced Technology Education Program of the Texas Higher Education Coordination Board and the National Science Foundation for the financial support. I want to thank Dr. Lisa Pérez for helping me with the quantum chemical calculations and for her assistance in the Laboratory of Molecular Simulation. In the same line, I have to thank the Supercomputing facility at Texas A&M for computer time. vii I am extremely grateful to my collaborators at Texas A&M at Prairie View (PVAMU), Dr. I. Osborne-Lee and Mr. Collin Kwabbi for letting me participate in the acquisition of some of the experimental data. I always felt welcome at PVAMU. I also need to recognize my excellent office mates, Mrs. Yanhua Qiao and Dr. Chunyang Wei for creating an excellent working environment. I was extremely blessed to share an office with both of you. Thanks to that we shared many concerns, frustrations, advice, jokes and, more than that, a sincere friendship. Last, but not least, I have to thank all my family and friends for all their love, support and faith. Mom, thank you very much for your unconditional and unselfish love. Marieberta thanks a lot for making me laugh in my most stressful times. You are one of a kind! Miguel, you set the example and we all follow you. Thanks for showing me to shoot for the stars. Nobody can replace the amazing support that I receive from all of you. You are definitely my most precious possession. viii TABLE OF CONTENTS Page ABSTRACT..................................................................................................................... iii DEDICATION ...................................................................................................................v ACKNOWLEDGEMENTS ..............................................................................................vi TABLE OF CONTENTS............................................................................................... viii LIST OF FIGURES...........................................................................................................xi LIST OF TABLES ......................................................................................................... xiii LIST OF ABBREVIATIONS .........................................................................................xiv LIST OF SYMBOLS .......................................................................................................xv CHAPTER I INTRODUCTION...............................................................................................1 1.1 Definition of Flammability Characteristics................................................2 1.2 Hazard Assessment ....................................................................................3 1.3 Statement of the Problem ...........................................................................4 1.4 Objectives...................................................................................................7 1.5 Organization of Dissertation ......................................................................8 II BACKGROUND...............................................................................................10 2.1 Flash Point Exprimental Methods............................................................11 2.2 Flash Point Theoretical Methods..............................................................12 2.2.1 Pure Compounds ..........................................................................13 2.2.2 Binary Mixtures............................................................................14 2.2.2.1 Aqueous Mixtures.........................................................16 2.2.2.2 Flammable Mixtures.....................................................16 2.3 Minimum Flash Point Behavior (MFPB).................................................18 2.4 Classification of Mixtures ........................................................................20 2.4.1 Activity Coefficient Models.........................................................20 ix CHAPTER Page 2.4.2 Infinite Dilution Activity Coefficients and Quantum Chemistry .....................................................................................23 III PROCEDURE FOR THE EVALUATION OF MIXTURE FLASH POINTS.............................................................................................................26 3.1 Purpose.....................................................................................................27 3.2 Initial Phase: Screening Methodology .....................................................28 3.3 Estimation of Binary Mixture Flash Point ...............................................31