Numerical simulations of coal gasification in entrained flow gasifiers with coalfoam

Numerical simulations of coal gasification in entrained flow gasifiers with coalfoam Danny Messig, Konrad Uebel, Martin Gräbner, Bernd Meyer Institute of Energy Process Engineering and Chemical Engineering Freiberg, Germany Fifth OpenFOAM Workshop Gothenburg

Contents 1 Introduction 2 Research project HotVeGas 3 Solver-package coalfoam 4 Preliminary results 5 Future work 2

Introduction Scope: Numerical simulation of an industrial coal gasifier with respect to the influence of mineral matter What is gasification? Gasification is a thermo-chemical process that converts carbonaceous materials (e.g. coal, biomass) into a combustible gas, yielding mainly CO and H 2. Typical conditions: 1000 1500 C, 30 bar, λ < 1, O 2, CO 2, H 2 O as gasifying agents Why gasification? Gaseous fuels are better to handle than solid ones Syngas may be burned in combined cycles for power production, used to produce methanol and hydrogen or converted via the Fischer-Tropsch process into synthetic fuel 4

Introduction Software used for numerical simulation: OpenFOAM-1.5.x [1]: Open-source software for CFD calculations ChemApp [2]: Commercial software for calculation of complex multicomponent and multiphase chemical equilibrium Cantera [3]: Open-source software package for kinetic controlled reaction rates and equilibrium calculations alternatechemistrymodel [4],[5]: Coupling of chemistry packages with OpenFOAM 5

Research project HotVeGas Tasks: Fundamental investigations in development of future high-temperature gasification and gas cleaning processes for IGCC power plants and for production of synthetic energy sources Basic analysis of the behaviour of coals and other heterogeneous energy sources with mineral content and trace elements at highest temperatures and pressures under reducing atmosphere Numerical simulation of a large scale coal gasifier (POI for now) Project period: 01.09.2007 till 31.08.2011 7

Research project HotVeGas Project partners: Department for Energy Process Engineering and Chemical Engineering - TU Freiberg Chair of Energy Systems [project coordinator] - TU Munich Institute of Energy Research - Forschungszentrum Jülich GTT-Technologies - Herzogenrath Siemens (Fuel Gasification Technology) - Freiberg Energy companies (E.ON, RWE, EnBW, Vattenfall) 8

Solver-package coalfoam What is coalfoam? OpenFOAM-solver-package for numerical simulation of coal gasification in an entrained flow gasifier coalsteadyfoam - stationary solver coaltransientfoam - transient solver Main developer Status: Bernhard F. W. Gschaider [6] Development and validation More detailed description: Article at Open Source CFD International Conference 2009 [7] 10

Preliminary results Actual proceedings in calculation/simulation: 1 2D-Case (tube reactor) for plausibilty tests [evaporation and devolatilization (pyrolysis)] 2 2D-Case (dualinlet) for testing of transport-equations in OpenFOAM 3 3D-Case of a large scale coal gasifier [INCI-Principle] 12

Tube reactor Case settings: Inert gas phase: Y N2 = 1.0, v 3 m s, T GAS {800, 1300, 1700} K, p = 5 bar Tube idealised as 2D-domain: x max = 1 m, y max = 0.1 m, 100 10 cells coal-parcels: ṁ GAS ṁ COAL = 3, d = 0.1 mm, Y P,Solid = 0.8 (ash), T COAL = 298 K Evaporation: Y P,Liquid = 0.2 (H 2 O) Devolatilization: Y P,Gas = 0.2 (CH 4 ) 13

Tube reactor Evaporation Conclusion: massflow at outlet correct (error < 0.1%) tendency of evaporation rate is correct 14

Tube reactor Devolatilzation Conclusion: massflow at outlet correct (error < 0.1%) tendency of pyrolysis rate is correct 15

dualinlet Case settings: Operating conditions: T = 1700 K, p = 5 bar XInlet: Y N2 = 1.0, v = (2 0 0) m s YInlet: Y H2 O = 1.0, v = (0-2 0) m s Grid: x max = 0.07 m, y max = 0.04 m, 1500 cells 16

dualinlet Results of dieselfoam-1.5.x: 17

dualinlet Results of dieselfoam-1.6.x: 18

dualinlet Bug removal in solvers: YEqn.H: old: (φ Y i ) ((µ Chem + µ t ) Y i ) = S Yi (( ) ) new: (φ Y i ) αchem Le + µt Sc t Y i = S Yi HEqn.H: old: (φ h) ((α Chem + µ t ) h) = S (( ) ) h new: (φ h) α Chem + µt P r t h = S h Dimensionless numbers: Le = a D, Lewis number P r = ν a, Prandtl number Sc = ν D, Schmidt number 19

dualinlet Results of coalsteadyfoam: 20

Coal gasifier INCI-Principle: Internal Circulation Gasifier allows high-ash/low-rank coal feed and combine: entrained flow gasifier (e.g. SCGP) (POI for the following simulation) fluidised bed gasifier (e.g. HTW) new principle of post-gasification Some advantages of INCI: Fouling free HRSG operation due to high dust carbon content High flame temperatures partial ash melting with agglomeration complete carbon and minerals oxidation 21

Coal gasifier First results: 22

Future work Finish the development and validation of coalfoam Modeling the influences of mineral matter with ChemApp in coalfoam Wall deposition of particles dependent on particle condition 24

Acknowledgement The results described above were obtained in the research project HotVeGas. The project was supported with public funding by the German Federal Ministry of Economics and Technology (Project ID 0327773B) 25

Literatur I [1] OpenFOAM, www.opencfd.co.uk/openfoam/. [2] http://www.gtt-technologies.de/chemapp. [3] DG Goodwin. Cantera: Object-oriented software for reacting flows. Technical report, California Institute of Technology, 2002. [4] Gschaider B., Rehm M., Seifert P., Meyer B. Implementation of an alternative chemistry library into openfoam. In Open Source CFD International Conference 2008, Berlin, 2008. [5] Messig D., Rehm M., Meyer B. Coupling of ChemApp and OpenFOAM. In CCT2009, Dresden, 2009. [6] Strömungsforschungs GmbH, http://www.ice-sf.at/cfd.shtml. 26

Literatur II [7] Messig D., Uebel K., Gschaider B., Gräbner M., Meyer B. Coal gasification solver coalfoam. In Open Source CFD International Conference 2009, Barcelona, 2009. 27