CFD Burner Study for Entrained Flow Gasifiers

Transcription

1 CFD Burner Study for Entrained Flow Gasifiers Numerical Study of Different Burner Configurations in an Entrained Flow gasifiers 1 H/C molar ratio CRC-252 LBC-3 RBC-2 LBC-2 CRC-272 RBC-1 LBC-1 Newland XHL CRC-274 CRC-358 CRC CPD O/C molar ratio Thomas Förster 1, Andreas Richter 1, Bernd Meyer 2 Institute of Energy Process Engineering and Chemical Engineering , IEC Seminar 1 Center for Innovation Competence Virtuhcon, Germany 2 Institute of Energy Process Engineering and Chemical Engineering, TU Bergakademie Freiberg, Germany

2 Motivation Burner Development for Entrained Flow Gasification Bader et. al. 2018, Fuel Proc. Techn. 169 State of the art Central jet flows Swirling and non-swirling jet flows 1 to 3 Distributed jet flows Subjects of interest Increasing performance Shortened flame Stability of the flame Higher reaction rates Zhang et. al. 2017, Can. J. of Chem. Eng. TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

3 Motivation Different Burner Concepts for Non-Catalytic Partitial Oxidation of Natural Gas Different burner concepts, Förster et. al. 2017, Fuel 203 Fuel Oxidizer + Steam 16 Oxidizer + Steam 77 Steam Fuel (jet) (plate) Förster et. al. 2017, Fuel 203 H 2 mass flow, kg/h ṁ H2, out jet 0 jet-swirl plate 10 spherical (spherical) Reactor length, mm 0 Copyright of reuse by Elsevier/Fuel via RightsLink is obtained for the cited images TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

4 Outline Burner Concepts Investigation for Entrained Flow Gasifiers Fuel and Process Analysis for a Comprehensive CFD Model Influence of the Burner Concept on the Reactor System Conclusion and Outlook TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

5 Burner Concepts Investigation for Entrained Flow Gasifiers Overview of the Reactor Design Siemens type gasifier Geometric boundary conditions Geometry of the reactor Geometry of the burners 1 Velocity profile of fuel inlet Velocity profile of the oxidizer inlet Velocity profile of the moderator inlet Characteristics of the conveying system Entrained flow coal gasifier (top fired) Central jet burner 5.4 m high and 2.3 m 1 Geometry influences the flow fields, Euler-Lagrange vs. real geometry TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

6 Burner Concepts Investigation for Entrained Flow Gasifiers Burner Concepts (Inverse Models) B1, central jet B2, peripheral jet Siemens type reactor B3, plate B4, spherical TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

7 Burner Concepts Investigation for Entrained Flow Gasifiers Mesh B1 and B2 central jets B3, plate B4, spherical Dimension: 2D, axis-symmetric Size: 30k Type: structured, quadrilateral Calculation time: 7 days Dimension: 3D, symmetry Size: 900k Type: structured, hexahedral Calculation time: 50 days Dimension: 3D, symmetry Size: 800k Type: structured, hexahedral Calculation time: 50 days TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

8 Burner Concepts Investigation for Entrained Flow Gasifiers CFD Setup Setup for the CFD setup of the Siemens type gasifier 1 Solver ANSYS Fluent Turbulence realizable k-ε model Radiation DO model Turbulence chemical interaction Eddy-Dissipation Concept Model Homogeneous mechanism reduced GRI Gas phase properties kinetic theory Particle tracking Euler-Lagrange 1 Safronov et al. 2017, Fuel Proc. Techn Kazakov and Frenklach 1995, 3 Badzioch and Hawksley 1970, Ind. Eng. Chem. Proc. Des. and Develop. 9(4) TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

9 Fuel and Process Analysis for a Comprehensive CFD Model Input Streams Necessary operational boundary conditions Coal inlet Oxidizer inlet Moderator inlet Purge inlet Wall temperatures ṁ coal, T coal ṁ ox, T ox ṁ mod, T mod ṁ purge, T purge T reactor, T burner Boundary conditions criteria Min. gas temp. T gas T crit-η + 50 K Fuel-oxygen-ratio λ 0.4 to 0.5 Reactor pressure p op 31 bar(a) Carb. conv. target X goal maximum Thermal power Ḣ th 250 MW Remark Operational experience Equilibrium approach Non-equilibrium reduced order models Most reliable boundary conditions Fuel HHV h HHV,ar Newland hard coal Conveying system ε void 0.75 TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

10 Fuel and Process Analysis for a Comprehensive CFD Model Input Streams Approximation for the Current Setup General boundary conditions Fuel stream ṁ coal, kg s 9.0 ṁ CO2, kg s 1.0 T purge, K Example of burner boundary conditions Gasifying stream ṁ gas, kg s 7.5 x O2, x CO2, ,0.05 T gas, K Wall inlet region T burner, K Wall reactor T reactor, K Reactor pressure p op, bar(a) 31.0 TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

11 Fuel and Process Analysis for a Comprehensive CFD Model General Fuel Properties Standard anaylsis Ultimate analysis Proximate analysis Intrinsic surface Density and porosity Higher heating value Particle size distribution Ash characteristics (e.q. temperature of critical viscosity) Advanced measurements of the used fuel Pyrolysis rates and composition Heterogeneous reaction kinetics (CO 2 and H 2O) Remark All data need to be available for the same fuel TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

12 Fuel and Process Analysis for a Comprehensive CFD Model Pyrolysis Data Properties of the pyrolysis process Based on particle heating rates Experimental determination as close to the operation conditions as possible Comprises 1. Pyrolysis gas compositions and tar properties 2. Devolatilization rates for all participating species 3. Swelling index Goal is to use experimental data (e.q. PYMEQ rig) 1 No data set for the desired coal is available Use of network models is necessary 1 Reichel et al. 2015, Fuel 158 TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

13 Fuel and Process Analysis for a Comprehensive CFD Model Newland Coal 1 Proxymate analysis (ar), wt % FC VM Ash Moist Ultimate analysis (daf), wt % C H O N S Other properties Density (true), kg m HHV (ar), MJ kg Boundaries of the CPD in the van-krevelen diagram H/C molar ratio CRC-272 CRC-252 Newland XHL CRC-274 CRC-358 CRC-299 CPD O/C molar ratio LBC-3 RBC-2 LBC-2 RBC-1 LBC-1 1 Kajitani et al. 2003, Report W02021 TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

14 Fuel and Process Analysis for a Comprehensive CFD Model Results of the Chemical Percolation Model Particle temperature over time (CPD vs. SFOM) Particle temperature over time (CPD vs. C2SM) Final mass fraction yield, wt.% H 2O CH CO 5.40 CO Tar Tar dmp dt C 13.7H 21.4N 1.01 with M tar = 200 kg kmol ( ) = k [m p (1 f v,0)(1 f w,0) m p,0] with k = A exp EA T R u with A = J and EA = s mol Vol H 2O CH CO CO Tar TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

15 Fuel and Process Analysis for a Comprehensive CFD Model Heterogeneous Reaction Kinetics Literature data Reliability Availabiltiy mainly based on TGA measurements limited usability TGA Fast Reliable Several systems available at the institute Experience in model based data evaluation 1 Advantage in determining rate in kinetic controlled regime Drop tube KIVAN 2 Sophisticated and complex Closer to the real process Reliable for regime I + II Best kinetic data for entrained flow gasifiers Literature data 3 are adapted for surface based kinetics 4 1 Schulze et al. 2017, Fuel Gonzalez et al. 2018, Fuel Kajitani et al. 2002, Fuel 81 4 ANSYS Fluent Manual v172, ch. 7.3 TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

16 Influence of the Burner Concept on the Reactor System Flow Fields, Velocity Magnitude, v axial = 0 m s B1, jet central B1, swirl 60 B3, plate B4, spherical TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

17 Influence of the Burner Concept on the Reactor System Gas Residence Time B1, jet central B1, swirl 60 B3, plate B4, spherical TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

18 Influence of the Burner Concept on the Reactor System Overall Particle Residence Times B1, jet central B1, swirl 60 Count Residence time, s Count Residence time, s B3, plate B4, spherical Count Residence time, s Count Residence time, s TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

19 Influence of the Burner Concept on the Reactor System Heterogeneous Burnout, r C+O2 = 0.1 kmol m 3 s B1, jet central B1, swirl 60 B3, plate B4, spherical TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

20 Conclusion and Outlook Conclusion State of the art CFD models for detailed conversion analysis are available Different burner concepts including swirl were investigated for the prove of general concept The burner configuration has a great impact on flow and particle dynamics in a reactor Findings for single-phase systems cannot be transfered directly to multiphase systems. Next steps Additional burner concepts will be studied Implementation of new fuel datasets based on in-house measurements Usage of ROMs for a better pre-assessment of boundary conditions for CFD TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers

21 Thank you for your kind attention! This research has been funded as part of ProVirt by the European Social Fund (ESF) and the Free State of Saxony (project number ). TU Bergakademie Freiberg T. Förster et al. CFD Burner Study for Entrained Flow Gasifiers