Silesian University Clausthal University of Technology of Technology Faculty of Energy Faculty of Energy and Environmental Engineering and Management Institute of Thermal Technology Institute of Energy Process Engineering and Fuel Technology Ph.D. thesis Ecological evaluation of the pulverized coal combustion in HTAC technology Natalia SCHAFFEL-MANCINI This thesis was realized in the frame of the agreement between Silesian University of Technology and Clausthal University of Technology for Ph.D. projects Gliwice - Clausthal-Zellerfeld 2009 ii Politechnika Śląska Uniwersytet Techniczny w Gliwicach w Clausthal Wydział Inżynierii Środowiska Wydział Energii i Energetyki i Nauk Ekonomicznych Instytut Techniki Cieplnej Instytut Energetycznej Inżynierii Procesowej i Technologii Paliw Praca doktorska Ocena ekologiczna procesu spalania pyłu węglowego w technologii HTAC Natalia SCHAFFEL-MANCINI Praca doktorska powstała w ramach umowy o podwójnym doktoracie zawartej pomiędzy Politechniką Śląską w Gliwicach i Uniwersytetem Technicznym w Clausthal Gliwice - Clausthal-Zellerfeld 2009 iv Schlesische Technische Universität Technische Universität in Gliwice Clausthal Fakultät für Energie Fakultät für Energie- und Umwelttechnik und Wirtschaftswissenschaften Institut für Hochtemperaturtechnik Institut für Energieverfahrenstechnik und Brennstofftechnik Dissertation Ökologische Bewertung der HTAC-Kohlestaubverbrennungsmethode Natalia SCHAFFEL-MANCINI Diese Dissertation wurde im Rahmen der Doppelpromotionsvereinbarung zwischen der Schlesischen Technischen Universität und der Technischen Universität Clausthal ausgefertigt Gliwice - Clausthal-Zellerfeld 2009 Author: Mgr inż. Natalia Schaffel-Mancini Dipl.-Ing. Natalia Schaffel-Mancini Silesian University of Technology Clausthal University of Technology Faculty of Energy Faculty of Energy and Environmental Engineering and Management Institute of Thermal Technology Institute of Energy Process Engineering and Fuel Technology ul. Konarskiego 22 Agricolastr. 4 PL-44 100 Gliwice, Poland D-38 678 Clausthal-Zellerfeld, Germany e-mail: [email protected] e-mail: [email protected] Supervisors: Prof. dr hab. inż. Andrzej Szlęk Prof. Dr.-Ing. Roman Weber Silesian University of Technology Clausthal University of Technology Faculty of Energy Faculty of Energy and Environmental Engineering and Management Institute of Thermal Technology Institute of Energy Process Engineering and Fuel Technology ul. Konarskiego 22 Agricolastr. 4 PL-44 100 Gliwice, Poland D-38 678 Clausthal-Zellerfeld, Germany e-mail: [email protected] e-mail: [email protected] Reviewers: Prof. dr hab. inż. Marek Pronobis D. Sc. (Tech.), Professor Antti Oksanen Silesian University of Technology Tampere University of Technology Faculty of Energy Faculty of Science and Environmental Engineering and Environmental Engineering Institute of Power Engineering Department of Energy and Turbomachinery and Process Engineering ul. Konarskiego 20 PO Box 589 PL-44 100 Gliwice, Poland FIN-33 101 Tampere, Finland e-mail: [email protected] e-mail: [email protected] vi Contents Abstract....................................... xix Streszczenie ..................................... xxi Kurzfassung..................................... xxiii Acknowledgments.................................. xxv Introduction..................................... xxvii Motivation...................................... xxvii Objectives...................................... xxviii 1 Coal in power generation 1 1.1 Overviewofcoalutilities . .. 1 1.2 Environmental issues of coal utilization . ....... 3 1.3 Coal based technologies for power generation . ....... 5 1.3.1 Pulverized coal (PC) combustion systems . ... 6 1.3.2 Fluidized bed combustion (FBC) systems . .. 7 1.3.3 Combustion under O2/CO2 atmosphere............... 8 1.3.4 Coalgasification(CG)technology . 9 1.3.5 Integrated Gasification Combined-Cycle (IGCC) systems ..... 11 1.3.6 Integrated Gasification Fuel Cells (IGFC) systems . ...... 11 1.4 Pulverized coal fired power plants . ... 12 1.4.1 Subcriticalinstallations. .. 14 1.4.2 Supercriticalinstallations . .. 14 1.4.3 Ultra-supercritical installations . ..... 15 1.5 High temperature materials for steam power plants . ....... 15 1.6 Rankinecycle ................................. 17 1.7 Issues for higher efficiency . 18 1.7.1 Steampressure ............................ 18 1.7.2 Steamtemperature .......................... 19 1.7.3 Exitgastemperature . .. .. 19 1.7.4 Excessairratio ............................ 19 vii 1.7.5 Unburnedcarbon ........................... 20 1.8 Pulverized coal (PC) boilers for power generation . ........ 20 1.8.1 Drumtypeboilers .......................... 21 1.8.2 Once-throughtypeboilers . 22 2 Overview of HTAC technology 27 2.1 Development of HTAC technology . 27 2.2 Current investigations and challenges of HTAC technology ........ 30 2.3 ModelingofHTACtechnology. 34 2.4 Basic implementations of HTAC technology . .... 39 2.5 Application of HTAC technology in furnaces . ..... 41 2.6 Application of HTAC technology in boilers . ..... 42 3 Mathematical model 45 3.1 The governing partial differential equations . ........ 45 3.1.1 Thecontinuityequation . 46 3.1.2 TheNavier-Stokesequation . 46 3.1.3 The conservation equation of chemical species . ..... 46 3.1.4 Theenergyequation ......................... 47 3.1.5 Theequationofstate. .. .. 47 3.1.6 The general governing differential equation . ..... 47 3.2 Averaging of the governing partial differential equations.......... 48 3.2.1 Reynoldsaveraging . .. .. 49 3.2.2 Favreaveraging ............................ 49 3.3 Set of the mathematical sub-models . ... 51 3.4 Turbulence................................... 51 3.5 Turbulentgascombustion . 52 3.5.1 Turbulence-chemistry interaction models . ..... 54 3.5.2 EddyBreakUpModel ........................ 54 3.5.3 EddyDissipationModel . 55 3.5.4 Eddy Dissipation Concept . 56 3.6 Particlebehavior ............................... 56 3.6.1 Trajectorycalculations . 57 3.6.2 Heat and mass transfer calculations . .. 58 3.7 Pulverizedcoalcombustion. .. 60 3.7.1 Coaldevolatilization . .. .. 60 3.7.2 Combustionofvolatiles. 65 viii 3.7.3 Charcombustion ........................... 65 3.8 Radiativeheattransfer . 68 3.9 Nitricoxides.................................. 68 4 Model validation 73 4.1 Experimentalequipment . 73 4.1.1 Furnace ................................ 73 4.1.2 Precombustor ............................. 74 4.1.3 Burnerblock ............................. 75 4.2 Measurements................................. 75 4.3 Coalcharacterization . 76 4.4 Numericalmodeling.............................. 80 4.4.1 Model geometry and calculation procedure . ... 80 4.4.2 Flowfieldandrecirculation . 82 4.4.3 Temperature field and radiative heat fluxes . ... 82 4.4.4 Oxygen and carbon dioxide concentrations . ... 83 4.4.5 Carbonmonoxideconcentration . 84 4.4.6 Volatilesconcentration . 85 4.4.7 Nitricoxideconcentration . 86 4.4.8 Charburnout ............................. 88 4.4.9 Furnaceoutlet............................. 88 4.5 Findings.................................... 89 5 Design of the HTAC boiler 91 5.1 ShapeoftheHTACboiler .......................... 91 5.1.1 Resultsanddiscussion . 93 5.1.2 Findings................................ 95 5.2 Distance between individual burners . .... 96 5.2.1 Resultsanddiscussion . 97 5.2.2 Findings................................ 99 5.3 Locationoftheburnerblock . 100 5.3.1 Resultsanddiscussion . 101 5.3.2 Findings................................ 103 5.4 DimensionsoftheHTACboiler . 104 5.4.1 Resultsanddiscussion . 104 5.4.2 Findings................................ 106 ix 6 Final HTAC boiler design 107 6.1 Resultsanddiscussion . .. .. 109 6.1.1 Velocityandrecirculation . 109 6.1.2 Temperature.............................. 111 6.1.3 Oxygenconcentration . 111 6.1.4 Coalparticlesbehavior . 113 6.1.5 Heattransfer ............................. 115 6.2 Findings.................................... 116 7 Evaluation of the grid sensitivity 117 7.1 Gridindependence .............................. 118 7.2 Gridquality.................................. 119 7.2.1 Node-pointdistribution. 120 7.2.2 Smoothness .............................. 120 7.2.3 Cellshape............................... 121 8 Environmental issues 123 8.1 Nitricoxidesemissions . 123 8.2 Carbon monoxide and volatiles emissions . ..... 126 8.3 Charburnout ................................. 127 8.4 Findings.................................... 127 9 Effects of selected operating parameters 129 9.1 Impact of the combustion air preheat . ... 129 9.1.1 Resultsanddiscussion . 130 9.1.2 Findings................................ 134 9.2 The HTAC boiler equipped with low-momentum burners . ..... 134 9.2.1 Resultsanddiscussion . 135 9.2.2 Findings................................ 138 9.3 The HTAC boiler operated at nearly stoichiometric conditions . 139 9.3.1 Resultsanddiscussion . 139 9.3.2 Findings................................ 141 10 Coupling between the HTAC boiler and the steam cycle 143 10.1 Resultsanddiscussion . 146 10.2Cycleefficiency ................................ 150 10.3Findings.................................... 151 x 11 Conclusions and future works 153 Nomenclature 156 Bibliography 163 Extendedabstract ................................. 179 Obszernestreszczenie. .. .. .. 184 Zusammenfassung.................................. 189 xi xii List of Tables 1.1 Emission limit values for NOx, SO2 anddust ............... 4 3.1 Comburent composition and properties . .... 48 3.2