Influence of Coal Dust on Premixed Turbulent Methane-Air Flames Scott R. Rockwell A Dissertation Submitted to the Faculty of Worcester Polytechnic Institute In partial fulfillment of the requirements for the Degree of Doctor of Philosophy in Fire Protection Engineering July 2012 APPROVED: _____________________________________________ Professor Ali S. Rangwala, Advisor _____________________________________________ Professor Kathy A. Notarianni, Head of Department _____________________________________________ Professor Simon W. Evans _____________________________________________ Professor Sanjeeva Balasuriya _____________________________________________ Dr. Alfonso F. Ibarreta _____________________________________________ Professor Forman A. Williams Table of Contents Table of Contents ............................................................................................................................ 2 List of figures .................................................................................................................................. 5 List of tables .................................................................................................................................... 6 Nomenclature .................................................................................................................................. 7 Acknowledgments........................................................................................................................... 8 Abstract ........................................................................................................................................... 9 1. Introduction ............................................................................................................................... 10 1.1 General overview ................................................................................................................ 10 1.2 Hazard assessment used in dust industry ........................................................................... 11 1.3 The explosion sphere .......................................................................................................... 12 1.4 Prior related work ............................................................................................................... 18 1.4.1 Laminar dust flame experiments .................................................................................. 18 1.4.2 Turbulent dust flame experiments ............................................................................... 30 1.4.3 Hybrid flame experiments ............................................................................................ 32 1.4.4 Modeling of dust flames ............................................................................................... 33 1.5 Goals and objectives of the current study .......................................................................... 33 1.6 Organization of the thesis ................................................................................................... 35 References ................................................................................................................................. 35 2. Structure of a Dust Flame ......................................................................................................... 40 2.1. Premixed or Non-Premixed? .............................................................................................. 40 2.2 Flame structure ................................................................................................................... 41 3. Experimental Apparatus Construction and Procedure .............................................................. 49 3.1 Summary ............................................................................................................................. 49 3.2 Combustion chamber .......................................................................................................... 49 3.3 Exhaust system .................................................................................................................... 52 3.4 Burner test section .............................................................................................................. 53 3.5 Burner nozzle design ........................................................................................................... 55 3.6 Fuel control system ............................................................................................................. 62 3.7 Optical system ..................................................................................................................... 65 2 3.8 Directions for using HFA ...................................................................................................... 67 3.9 HFA data analysis ................................................................................................................ 67 3.11 Experimental matrix .......................................................................................................... 73 References ................................................................................................................................. 73 4. Results and Analysis ................................................................................................................. 76 4.1 Laminar flames .................................................................................................................... 76 4.2 Turbulent flames ................................................................................................................. 80 4.2.1 Gas flames (validation study) ....................................................................................... 80 4.2.2 Turbulent combustion regimes .................................................................................... 87 4.2.4 Effect of dust concentration on burning velocity ......................................................... 98 4.3 Correlation of turbulent burning velocity ......................................................................... 100 References ............................................................................................................................... 103 5. Conclusions and recommendations......................................................................................... 105 Appendix 2: HFA User’s Manual ............................................................................................... 111 Recommended Personal Protective Equipment (PPE) ............................................................... 113 Turning on HFA:......................................................................................................................... 114 Calibration: ................................................................................................................................. 119 Things to check: .......................................................................................................................... 121 Starting/Running test: ................................................................................................................. 123 Collecting gas analysis data: ....................................................................................................... 125 Turning off Experiment: ............................................................................................................. 127 MATLAB Scripts........................................................................................................................ 128 Using Hotwire Anemometer: ...................................................................................................... 129 Appendix 3: Matlab scripts used in data analysis ....................................................................... 132 Contents .................................................................................................................................. 132 A3.1 - Edge selection script ..................................................................................................... 133 A3.2 - Edge data analysis script ............................................................................................... 136 A3.3 - Plotting figure 4.9 ......................................................................................................... 153 A3.4 - Plotting figure 4.13 ....................................................................................................... 157 A3.5 - Plotting figure 4.14 ....................................................................................................... 160 3 A3.6 - Plotting figure 4.15 ....................................................................................................... 165 A3.7 - Creating arrays of test data as a function of dust concentration ( Burn_vel_func_dst_part_szev01) ........................................................................................... 170 A3.8 - Turbulent intensity calculation ..................................................................................... 190 A3.9 - Gas analysis data retrieval ............................................................................................ 193 A3.10 - plotAverage_noplot .................................................................................................... 194 Appendix 4: Error Bar values – standard deviation of velocity calculation ..............................