Entrained flow gasification. Part 3: Insight into the injector near-field by Large Eddy Simulation with detailed chemistry

Abstract Entrained flow gasification is a promising process for the conversion of low-grade feedstock, e.g. highly viscous slurries and suspensions with a significant content of solid particles, to high quality fuels. A major scientific challenge is the prediction of the physical and chemical phenomena occurring in such high-temperature and high-pressure multiphase flow systems. In this context, this article is the sequel to “Entrained flow gasification. Part 1: Gasification of glycol in an atmospheric-pressure experimental rig ” [1] and “Entrained flow gasification. Part 2: Mathematical modeling of the gasifier using RANS method ” [2] . The same strategy as in the first two parts was followed. In order to reduce complexity, this study focused on a two-phase (gas and liquid) flow system with a model fuel (mono-ethylene glycol) under the simplified conditions provided by the atmospheric lab-scale gasifier REGA. Using the experimental data set provided in Part 1 of the coordinated papers for validation purposes, the main focus of this study was on the detailed understanding of the near injector region of the entrained flow gasifier REGA. The unsteady flow and the chemical conversion in the gasifier were investigated by means of Large Eddy Simulations with a detailed chemistry solver including 44 individual species and a direct calculation of 329 chemical reactions. The dispersed phase was solved by Lagrangian Particle Tracking. Downstream comparisons with experimental data showed a reasonable agreement concerning temperature and species profiles. The analysis of the injector near-field revealed that the high temperature reaction zone close to the injector could not be explained by a direct reaction of the fuel with the oxidizer. Instead, carbon monoxide and hydrogen mainly formed on the axis were transported upstream by the recirculation zone. The reaction of CO and H 2 with the oxygen stabilized the flame. The heat release from this reactions supported the vaporization and decomposition of fuel as well as the downstream gasification reactions.

[1]  Cameron Tropea,et al.  Optical Particle Characterization in Flows , 2011 .

[2]  Simone Hafner.  Modellentwicklung zur numerischen Simulation eines Flugstromvergasers für Biomasse , 2010 .

[3]  Axel Probst,et al.  Scale-Resolving Simulations with a Low-Dissipation Low-Dispersion Second-Order Scheme for Unstructured Finite-Volume Flow Solvers , 2015 .

[4]  T. Poinsot,et al.  Theoretical and numerical combustion , 2001 .

[5]  F. Nicoud,et al.  Wall-Adapting Local Eddy-Viscosity models for simulations in complex geometries , 2007 .

[6]  Roman Weber,et al.  Entrained flow gasification Part 1: Gasification of glycol in an atmospheric-pressure experimental rig , 2018 .

[7]  W. Sirignano,et al.  Droplet vaporization model for spray combustion calculations , 1989 .

[8]  Pierre Sagaut,et al.  Multiscale And Multiresolution Approaches In Turbulence , 2006 .

[9]  O. T. Stein,et al.  Towards Comprehensive Coal Combustion Modelling for LES , 2013 .

[11]  M. D. Domenico.  Numerical simulations of soot formation in turbulent flows , 2008 .

[12]  M. Boileau,et al.  Investigation of Two-Fluid Methods for Large Eddy Simulation of Spray Combustion in Gas Turbines , 2008 .

[13]  Manfred Aigner,et al.  Tackling the challenges in modelling entrained-flow gasification of low-grade feedstock , 2016 .

[14]  Roman Weber,et al.  Gasification of high viscous slurry R&D on atomization and numerical simulation , 2012 .

[15]  A. Sadiki,et al.  Partially premixed reacting acetone spray using LES and FGM tabulated chemistry , 2012 .

[16]  Peter Gerlinger.  Numerische Verbrennungssimulation : effiziente numerische Simulation turbulenter Verbrennung , 2005 .

[17]  C. Naumann,et al.  Kinetics of Ethylene Glycol: The first validated reaction scheme and first measurements of ignition delay times and speciation data , 2017 .

[18]  W. Jones,et al.  LES of a methanol spray flame with a stochastic sub-grid model , 2015 .

[19]  B. Morreale,et al.  High-Temperature Kinetics of the Homogeneous Reverse Water-Gas Shift Reaction , 2004 .

[20]  T. Kolba,et al.  Entrained flow gasification Part 1_ Gasification of glycol in an atmospheric-pressure experimental rig , 2017 .

[21]  K. Kuo.  Principles of combustion , 1986 .

[22]  Salvador Navarro-Martinez,et al.  Large Eddy simulation of a pulverised coal jet flame , 2013 .

[23]  Jeremy N. Thornock,et al.  Large Eddy Simulation of Pulverized Coal Jet Flame Ignition Using the Direct Quadrature Method of Moments , 2012 .

[24]  Suresh Menon,et al.  Simulation of spray–turbulence–flame interactions in a lean direct injection combustor , 2008 .

[25]  W. P. Jones,et al.  Large-eddy simulation of particle-laden turbulent flows , 2008, Journal of Fluid Mechanics.

[26]  A. Masri,et al.  Influence of spray/combustion interactions on auto-ignition of methanol spray flames , 2015 .

[27]  Ahmed F. Ghoniem,et al.  Large eddy simulations of coal gasification in an entrained flow gasifier , 2013 .

[28]  C. W. Gardiner,et al.  Handbook of stochastic methods - for physics, chemistry and the natural sciences, Second Edition , 1986, Springer series in synergetics.

[29]  Thierry Poinsot,et al.  LES Study of Transverse Acoustic Instabilities in a Swirled Kerosene/Air Combustion Chamber , 2016 .

[30]  Elizaveta Ivanova.  Numerical simulations of turbulent mixing in complex flows , 2012 .

[31]  Benjamin Franchetti,et al.  Large Eddy Simulation of coal combustion in a large-scale laboratory furnace , 2015 .

[32]  R. Clift,et al.  Bubbles, Drops, and Particles , 1978 .

[33]  Konstantina Vogiatzaki,et al.  Large-eddy simulation of spray combustion in a gas turbine combustor , 2014 .

[34]  O. Stein,et al.  LES-CMC of a dilute acetone spray flame , 2013 .

[35]  Robert W. Dibble,et al.  Combustion: Physical and Chemical Fundamentals, Modelling and Simulation, Experiments, Pollutant Formation , 1996 .

[36]  Martin Gräbner,et al.  Gasification of Solids: Past, Present, and Future , 2014 .

[37]  J. Bellan,et al.  Consistent large-eddy simulation of a temporal mixing layer laden with evaporating drops. Part 2. A posteriori modelling , 2005, Journal of Fluid Mechanics.

[38]  Tobias Knopp,et al.  Low-Dissipation Low-Dispersion Second-Order Scheme for Unstructured Finite Volume Flow Solvers , 2015 .

[39]  Uwe Riedel,et al.  A detailed chemical kinetic model of high-temperature ethylene glycol gasification , 2011 .

[40]  O. Stein,et al.  LES of swirl-stabilised pulverised coal combustion in IFRF furnace No.1 , 2015 .

[41]  F. Nicoud,et al.  Subgrid-Scale Stress Modelling Based on the Square of the Velocity Gradient Tensor , 1999 .