Implementation and validation of an advanced subgrid scale heterogeneous combustion model for coal gasification

Transcription

1 Implementation and validation of an advanced subgrid scale heterogeneous combustion model for coal gasification Michele Vascellari 1, Sebastian Schultze 2, Mathias Kestel 2,! Dmitry Safronov 2, Petr Nikrityuk 2, Christian Hasse 1!! ZIK Virtuhcon! 1 RSS Reacting Flow System group! 2 IPP InterPhase Phenomena group! TU Bergakademie Freiberg I Professur für Numerische Thermofluiddynamik Institut für Energieverfahrenstechnik und Chemieingenieurwesen Reiche Zeche I 9596 Freiberg I Tel. +49()3731/ I Fax +49()3731/

2 Outlook Development of new models for coal gasification at Virtuhcon SubGrid Scale (SGS) model for char heterogeneous reactions theory and development Coupling of SGS model in Ansys-Fluent Full scale validation of SGS model IFRF mild furnace Siemens gasifier Conclusions 2

3 Centre for Innovation Competence Virtuhcon" Development of advanced models for gasification 3

4 Char combustion SGS model" Development strategy Inter-Phase Phenomena Group (IPP) Reacting Flow System (RSS) group Coal particle DNS Theoretical model development Full scale CFD model of gasifier 4

5 Outlook Development of new models for coal gasification at Virtuhcon SubGrid Scale (SGS) model for char heterogeneous reactions theory and development Implementation of SGS model in Ansys-Fluent Full scale validation of SGS model IFRF mild furnace Siemens gasifier Conclusions 5

6 SGS char reactions model" Theoretical background Influence of homogenous reactions around the particle { rs C +.5 O 2 CO C + H O CO + H C + CO 2 CO r F r F { CO +.5 O 2 CO + H O CO2 CO + H Modeling of convection/diffusion S.Schulze et al. Submodel for a spherical char particle moving in a hot air/steam atmosphere. Submitted to Flow, Turbulence and Combustion 6

7 SGS char reactions model" Comparison with Baum and Street model (BS) Baum and Street (BS) model is the default model used by several CFD codes Results of SGS and BS model are compared to DNS of a single coal particle Baum, M. & Street, P. Predicting the Combustion Behaviour of Coal Particles Combustion Science and Technology, 1971, 3,

8 Outlook Development of new models for coal gasification at Virtuhcon SubGrid Scale (SGS) model for char heterogeneous reactions theory and development Coupling of SGS model in Ansys-Fluent Full scale validation of SGS model IFRF mild furnace Siemens gasifier Conclusions 8

9 Implementation of SGS model" Ansys-Fluent UDF coupling Gas phase: Eulerian Discrete phase: Lagrangian Injec1ons Drying Pyrolysis Char reac1ons Ash DEFINE_DPM_LAW IPP SUBGRID External pre/postprocessor to calculate pyrolysis kinetics and composition based on network based models 9

10 Outlook Development of new models for coal gasification at Virtuhcon SubGrid Scale (SGS) model for char heterogeneous reactions theory and development Implementation of SGS model in Ansys-Fluent Full scale validation of SGS model IFRF mild furnace Siemens gasifier Conclusions 1

11 Implementation of SGS model" Full scale validation Validation of SGS models considering full-scale test-cases No experimental data for industrial-scale gasifier No detailed experimental data for laboratory-scale gasifier No in-flame measurements PC combustion test-case can be used for validating SGS models In-flame measurements Temperature Species Velocity IFRF mild furnace Validation considering chemical species and temperature fields 11

12 Validation of SGS model" IFRF pc mild furnace 88kW multi-fuel furnace Recirculation of exhaust gas O 2 enriched High concentration of CO 2 and H 2 O About 4% of char conversion by gasification reactions Detailed in-flame measurements - Orsino et al. Tech. Rep. IFRF Doc. No. F46/y/3; Int. Flame Res. Foundation; 2. 12

13 SGS model validation" IFRF CO dry molar fraction z=5 m z=.44 m CO dry Experiments BS SGS z=.735 m z=1.32 m CO dry z=2.5 m z=3.22 m CO dry.5 1 x, m.5 1 x, m Radius of homogeneous zone d f /d p =1.1 13

14 SGS model validation" IFRF temperature z=5 m z=.44 m Temperature, K 2 Experiments BS SGS z=.735 m z=1.32 m 2 2 Temperature, K z=2.5 m z=3.22 m 2 2 Radius of homogeneous zone d f /d p =1.1 Temperature, K x, m x, m 14

15 SGS model validation" IFRF CO dry molar fraction z=5 m z=.44 m CO dry Experiments BS SGS z=.735 m z=1.32 m CO dry z=2.5 m z=3.22 m CO dry.5 1 x, m.5 1 x, m 15

16 SGS model validation" Siemens gasifier Enhanced char burnout Reduction of temperature in post-combustion zone 16

17 Outlook Development of new models for coal gasification at Virtuhcon SubGrid Scale (SGS) model for char heterogeneous reactions theory and development Implementation of SGS model in Ansys-Fluent Full scale validation of SGS model IFRF mild furnace Siemens gasifier Conclusions 17

18 Conclusions and future developments New SGS model for char heterogeneous combustion developed within Virtuhcon Validated considering single particle DNS Enhanced char consumption rate respect to standard BS Very good agreement with DNS Coupled to Ansys-Fluent by means of UDF Validation considering full-scale reactors Improved prediction of chemical species Further investigation regarding the influence of homogeneous reactions zone 18

19 Acknowledgments The authors acknowledge the Government of Saxony and the Federal Ministry of Education and Research of Germany for the financial support Implementation and validation of an advanced subgrid scale heterogeneous combustion model for coal gasification Michele Vascellari 1, Sebastian Schultze 2, Mathias Kestel 2, Dmitry Safronov 2, Petr Nikrityuk 2, Christian Hasse 1 19

20 Validation of SGS model" IFRF pc mild furnace - Orsino et al. Tech. Rep. IFRF Doc. No. F46/y/3; Int. Flame Res. Foundation; 2. 2

21 SGS model validation" Siemens gasifier Dry feed entrained gasifier 2 MW GSP-type (Siemens) Operating pressure: 3 bar m, kg/s T, K Composition, % vol. Coal Lusitian lignite Transport N2 1% Oxidant % O2, 14.46% H2O Proximate analysis (as received) Ultimate analysis (daf) Volatile matter C 67.4 Fixed carbon H 5.24 Moisture 1. O Ash 9. N. S. HHV as received (Dulong) 2.25 MJ/kg 21

22 CFD modeling of coal gasification" Numerical models Ansys-Fluent v.13 SIMPLE pressure-velocity coupling 2 nd order upwind for convective fluxes Eulerian-Lagrangian approach for two-phase flow Turbulence modeling: RANS with realizable k-² P1 model for radiation EDC with DRM mechanism for homogeneous chemistry Pyrolysis model: single rate law calibrated with CPD 22