cfd burner study for entrained flow gasiﬁers · 2018-06-27 · cfd burner study for entrained...

CFD Burner Study for Entrained Flow GasifiersNumerical Study of Different Burner Configurations in an Entrained Flow gasifiers

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0.6

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0.8

0.9

1

0 0.05 0.1 0.15 0.2 0.25 0.3

H/C

mol

arra

tio

O/C molar ratio

CPD

RBC-1

RBC-2

LBC-1

LBC-2

LBC-3CRC-252

CRC-272

CRC-274CRC-299CRC-358

XHLNewland

Thomas Förster1, Andreas Richter1, Bernd Meyer2

Institute of Energy Process Engineering and Chemical Engineering18.05.2018, IEC Seminar

1Center for Innovation Competence Virtuhcon, Germany2 Institute of Energy Process Engineering and Chemical Engineering, TU Bergakademie Freiberg, Germany

Motivation

Burner Development for Entrained Flow Gasification

State of the art

Central jet flows

Swirling and non-swirling jetflows

1 to 3 Distributed jet flows

Subjects of interest

Increasing performance

Shortened flame

Stability of the flame

Higher reaction rates

Bader et. al. 2018, Fuel Proc. Techn. 169

Zhang et. al. 2017, Can. J. of Chem. Eng.

TU Bergakademie Freiberg | T. Förster et al. | CFD Burner Study for Entrained Flow Gasifiers | 18.05.2018 1

Motivation

Different Burner Concepts for Non-Catalytic Partitial Oxidation of Natural Gas

Different burner concepts, Förster et. al. 2017, Fuel 203

Fuel

SteamOxidizer+ Steam

�16

(jet)

FuelOxidizer+ Steam

�77

(plate)

(spherical)

Förster et. al. 2017, Fuel 203

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−10

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60

0 50 100 150 200 250 300

H2massflo

w,kg/h

Reactor length,mm

jetjet-swirl

platespherical

mH2, out

0Copyright of reuse by Elsevier/Fuel via RightsLink is obtained for the cited images


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



Overview of the Reactor Design

Geometric boundary conditions

Geometry of the reactor

Geometry of the burners1

Velocity profile of fuel inletVelocity profile of the oxidizer inletVelocity profile of the moderator inletCharacteristics of the conveying system

Entrained flow coal gasifier (top fired)

Central jet burner

5.4 m high and � 2.3m

Siemens typegasifier

1Geometry influences the flow fields, Euler-Lagrange vs. real geometry



Burner Concepts (Inverse Models)

B1, central jet

B3, plate

B2, peripheral jet

B4, spherical

Siemens type reactor



Mesh

B1 and B2 central jets

Dimension: 2D,axis-symmetric

Size: 30k

Type: structured,quadrilateral

Calculation time:∼ 7 days

B3, plate

Dimension: 3D,symmetry

Size: 900k

Type: structured,hexahedral


B4, spherical

Dimension: 3D,symmetry

Size: 800k

Type: structured,hexahedral




CFD Setup

Setup for the CFD setup of the Siemens type gasifier1

Solver ANSYS Fluent

Turbulence realizable k-ε model

Radiation DO model

Turbulence chemical interaction Eddy-Dissipation Concept Model

Homogeneous mechanism reduced GRI 1.22

Gas phase properties kinetic theory

Particle tracking Euler-Lagrange

1Safronov et al. 2017, Fuel Proc. Techn. 1612Kazakov and Frenklach 1995, http://www.me.berkeley.edu/drm/3Badzioch and Hawksley 1970, Ind. Eng. Chem. Proc. Des. and Develop. 9(4)


http://www.me.berkeley.edu/drm/


Input Streams

Necessary operational boundary conditions

Coal inlet mcoal, Tcoal

Oxidizer inlet mox, Tox

Moderator inlet mmod, Tmod

Purge inlet mpurge, Tpurge

Wall temperatures Treactor, Tburner

Remark

Operational experience

Equilibrium approach

Non-equilibrium reduced order models

: Most reliable boundary conditions

Boundary conditions criteria

Min. gas temp. Tgas Tcrit-η + 50K

Fuel-oxygen-ratio λ 0.4 to 0.5

Reactor pressure pop 31 bar(a)

Carb. conv. target Xgoal maximum

Thermal power Hth ∼ 250MW

Fuel HHV ∆hHHV,ar Newlandhard coal

Conveying system εvoid ≈ 0.75



Input Streams Approximation for the Current Setup

General boundary conditions

Fuel stream mcoal,kgs 9.0

mCO2 , kgs 1.0

Tpurge, K 300.0

Gasifying stream mgas,kgs 7.5

xO2 , xCO2 , - 0.95,0.05

Tgas, K 653.0

Wall inlet region Tburner, K 300.0

Wall reactor Treactor, K 1600.0

Reactor pressure pop, bar(a) 31.0

Example of burner boundary conditions



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 (CO2 and H2O)

Remark All data need to be available for the same fuel



Pyrolysis Data

Properties of the pyrolysis process

Based on particle heating rates: Experimental determination as close to the operation conditions as possible

Comprises1. Pyrolysis gas compositions and tar properties2. Devolatilization rates for all participating species3. 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

1Reichel et al. 2015, Fuel 158



Newland Coal1

Proxymate analysis (ar), wt %

FC VM Ash Moist

55.6 27.8 13.4 3.2

Ultimate analysis (daf), wt %

C H O N S

82.50 5.11 10.61 1.36 0.42

Other properties

Density (true), kgm3 1456.0

HHV (ar), MJkg 28.88

Boundaries of the CPD in the van-Krevelendiagram

0.5

0.6

0.7

0.8

0.9

1

0 0.05 0.1 0.15 0.2 0.25 0.3

H/C

mol

arra

tio

O/C molar ratio

CPD

RBC-1

RBC-2

LBC-1

LBC-2

LBC-3CRC-252

CRC-272

CRC-274CRC-299CRC-358

XHLNewland

1Kajitani et al. 2003, Report W02021



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.%

H2O 12.00

CH4 6.27

CO 5.40

CO2 3.49

Tar 20.15

Tar

C13.7H21.4N1.01

with Mtar = 200 kgkmol

−dmp

dt= k · [mp − (1− fv,0)(1− fw,0) ·mp,0] with k = A · exp

(− EAT ·Ru

)with A = 13 436 655 1

sand EA = 80 970 J

mol

Vol −−→ 0.4659 H2O + 0.2734 CH4 + 0.1348 CO + 0.0555 CO2 + 0.0705 Tar



Heterogeneous Reaction Kinetics

Literature data

Reliability ⇓Availabiltiy ⇑mainly based on TGAmeasurements

: limited usability

TGA

Fast

Reliable

Several systems availableat the institute

Experience in modelbased data evaluation1

: Advantage indetermining rate inkinetic controlled regime

Drop tube

KIVAN2

Sophisticated andcomplex

Closer to the real process

Reliable for regime I + II

: Best kinetic data forentrained flow gasifiers

Literature data3 are adapted for surface based kinetics4

1Schulze et al. 2017, Fuel 1872Gonzalez et al. 2018, Fuel 2243Kajitani et al. 2002, Fuel 814ANSYS Fluent Manual v172, ch. 7.3



Flow Fields, Velocity Magnitude, vaxial = 0 ms

B1, jet central B1, swirl 60◦ B3, plate B4, spherical



Gas Residence Time




Overall Particle Residence Times

B1, jet central

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Cou

nt

Residence time, s

B3, plate

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Residence time, s

B1, swirl 60◦

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Residence time, s

B4, spherical

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Heterogeneous Burnout, rC+O2 = 0.1 kmolm3 s



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 generalconcept

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


Thank you for your kind attention!This research has been funded as part of ProVirt by the European Social Fund (ESF) and theFree State of Saxony (project number 100231952).


cfd burner study for entrained flow gasiﬁers · 2018-06-27 · cfd burner study for entrained...

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