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Research Papers: Fuel Combustion

Reaction Kinetics of Pressurized Entrained Flow Coal Gasification: Computational Fluid Dynamics Simulation of a 5 MW Siemens Test Gasifier

[+] Author and Article Information
Stefan Halama

Lehrstuhl für Energiesysteme,
Technische Universität München,
Boltzmannstr. 15,
Garching 85748, Germany
e-mail: stefan.halama@tum.de

Hartmut Spliethoff

Lehrstuhl für Energiesysteme,
Technische Universität München,
Boltzmannstr. 15,
Garching 85748, Germany;
ZAE Bayern (Bavarian Center for
Applied Energy Research),
Walther-Meissner-Str. 6,
Garching 85748, Germany
e-mail: spliethoff@tum.de

1Corresponding author.

Contributed by the Advanced Energy Systems Division of ASME for publication in the JOURNAL OF ENERGY RESOURCES TECHNOLOGY. Manuscript received August 14, 2015; final manuscript received January 12, 2016; published online February 22, 2016. Assoc. Editor: Yiannis Levendis.

J. Energy Resour. Technol 138(4), 042204 (Feb 22, 2016) (8 pages) Paper No: JERT-15-1308; doi: 10.1115/1.4032620 History: Received August 14, 2015; Revised January 12, 2016

Modeling pressurized entrained flow gasification of solid fuels plays an important role in the development of integrated gasification combined cycle (IGCC) power plants and other gasification applications. A better understanding of the underlying reaction kinetics is essential for the design and optimization of entrained flow gasifiers—in particular at operating conditions relevant to large-scale industrial gasifiers. The presented computational fluid dynamics (CFD) simulations aim to predict conversion rates as well as product gas compositions in entrained flow gasifiers. The simulations are based on the software ansys fluent 15.0 and include several detailed submodels in user defined functions (UDF). In a previous publication, the developed CFD model has been validated for a Rhenish lignite against experimental data, obtained from a pilot-scale entrained flow gasifier operated at the Technische Universität München. In the presented work, the validated CFD model is applied to a Siemens test gasifier geometry. Simulation results and characteristic parameters, with focus on char gasification reactions, are analyzed in detail and provide new insights into the gasification process.

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Figures

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Fig. 1

Flow chart of the implemented particle conversion model [6]

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Fig. 2

Siemens test gasifier setup [27], with intersecting planes (x1 xn) used for post processing

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Fig. 3

Normalized gas temperature (left) and streamlines with normalized gas velocity (right) on the symmetry plane of the reactor

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Fig. 4

Normalized reaction rates of char reactions with oxygen, steam, and carbon dioxide on the symmetry plane of the reactor

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Fig. 5

Mass-weighted average of char conversion in the entire reactor (a) and in the core flow (b)

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Fig. 6

Particles on the symmetry plane of the reactor, colored by char conversion; left: all particle diameters, right: particle diameters larger than 120 μm

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Fig. 7

Mass-weighted averages of gas species mole fractions in the reactor; Vol.: released volatiles, Equil.: computed water–gas shift equilibrium composition at the reactor outlet

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Fig. 8

Gas species mole fractions on the symmetry plane of the reactor

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Fig. 9

Mass-weighted averages of effectiveness factors for the char reactions with oxygen, carbon dioxide, and steam, as well as the reaction-rate-weighted mean effectiveness factor in the reactor

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Fig. 10

Reaction-rate-weighted mean effectiveness factor as a function of particle temperature, with each circle representing a reacting particle. The circle diameter is proportional tothe particle diameter, and the color indicates the position of the particle in the reactor (x1xn, see Fig. 2).

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Fig. 11

Reaction-rate-weighted mean effectiveness factor as a function of particle diameter, with each circle representing a reacting particle. The circle diameter is proportional to the particle diameter, and the color indicates the position of the particle in the reactor (x1xn, see Fig. 2).

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