View
3
Download
0
Category
Preview:
Citation preview
CFD MODELING OF TRICKLE BED REACTORS: Hydro-processing Reactor
Prashant R. Gunjal, Amit Arora and Vivek V. Ranade
Industrial Flow Modeling GroupNational Chemical Laboratory
Pune 411008Email: vvranade@ifmg.ncl.res.in
CFD Modeling of Trickle Bed Reactors
OUTLINE
• Trickle Bed Reactors– Applications/ flow regimes– Experiments
• CFD Modeling of Trickle Bed Reactors– Inter-phase momentum exchange/ capillary terms– Estimation of fraction of liquid suspended in gas phase
• Simulating Hydro-processing Reactor– Reaction kinetics/ other sub-models– Influence of reactor scale
• Concluding Remarks
CFD Modeling of Trickle Bed Reactors
TRICKLE BED REACTORS
• Wide Applications– Hydro-de-sulfurization– Hydro-cracking/ hydro-treating– Hydrogenation/ oxidation– Waste water treatment
• Key Characteristics– Close to plug flow/ Low liquid hold-up– Suitable for slow reactions
– Poor heat transfer/ possibility of mal-distribution– Difficult scale-up
CFD Modeling of Trickle Bed Reactors
TRICKLE BED REACTORS
Gas & Liquid Flow through Void Spaceε = 26-48 %
GasLiquid
CFD Modeling of Trickle Bed Reactors
FLUID DYNAMICS OF TBR
Characterization of Packed Bed
Wetting of Solid Surface by
Liquid
Flow Regimes & Global Flow
Characteristics
Mal-distribution, Channeling &
Mixing
ε, ∆P, αL, η, RTD
CFD Modeling of Trickle Bed Reactors
FLOW REGIMES
CFD Modeling of Trickle Bed Reactors
EXPERIMENTS AT NCL
• Hydrodynamics– Pressure Drop– Liquid Hold-up
• Conductivity Probes– Residence Time Distribution
• Liquid Distribution at Inlet– Uniform– Non-uniform
• Experimental Parameters– Bed Diameter: 0.1 & 0.2 m– Particle Diameter: 3 & 6 mm– Liquid Velocity: < 24 mm/ s – Gas Velocity: < 0.50 m/ s– Tracer : NaCl
Data Acquisition
From Compressor Liquid Tank
Column with 3mm or 6mm Glass Beads
SeparatorConductivity
Probe
101
Pressure Indicator
Pump
CFD Modeling of Trickle Bed Reactors
TYPICAL PRESSURE DROP DATA
0
5
10
15
20
25
30
35
0 10 20 30Liquid Flow Rate, Kg/m2s
Pres
sure
gra
dien
t, K
Pa/m
Trickle f low regime
Pulse f low regime
CFD Modeling of Trickle Bed Reactors
PUBLISHED EXPERIMENTAL DATA
00.20.40.60.8
1
1.21.41.61.8
2
0 5 10 15 20 25
Liquid Velocity VL, (Kg/m2s)
Supe
rfic
ial G
as V
eloc
ity V
g, (m
/s)
φL= ?
Trickle Flow1
3
1. Szady and Sundersan (1991)2. Rao et. al (1983) 3. Specchia and Baldi (1977)
Pulse Flow
Spray Flow
Bubbly Flow
φL=βL
φL=?
φL βL
2
CFD Modeling of Trickle Bed Reactors
MODELING OF MACROSCOPIC FLOW
• Bed Porosity: Scale of Scrutiny
– Bed diameter/ length: overall ε– Intermediate scale: Gaussian distribution– Smaller than particle diameter: Bi-modal distribution
• Approach Used:
– Experimentally measured or estimated radial variation of axially averaged bed porosity
– Specify porosity by drawing a sample assuming Gaussian distribution with specified variance
CFD Modeling of Trickle Bed Reactors
CHARACTERIZATION OF PACKED BED
• Radial Variation of Porosity: Mueller (1991)
( )
( )
( )
Function Besselorder zero is J and r/Dr
D/d0.724-0.304b
D/d13.0for 9.864D/d
2.932-7.383a
13.0D/d2.61for 3.156D/d
12.98-8.243a
)e(ar)Jε(1εrε
tho
*P
PP
PP
br*oBB
=
=
≤−
=
≤≤−
=
−+= −
CFD Modeling of Trickle Bed Reactors
CHARACTERIZATION OF PACKED BED
• Mueller’s CorrelationThree data sets from literature Our experiments
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 0.2 0.4 0.6 0.8 1Dimensionless Radius
Por
osity
D=0.194m, dp=3mm
D=0.194m, dp=6mm
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 0.2 0.4 0.6 0.8 1
Dimensionless Radius
Poro
sity
Szady and Sundersan (1991)
Rao et.al. (1983)
Spacchia and Baldi (1977)
CFD Modeling of Trickle Bed Reactors
VARIATION OF BED POROSITY
– Selection of appropriate value is not straight forward: RTD may help
r/R
0.70
0.56 With std dev=0
With std dev=5%
With std dev=10%
CFD Modeling of Trickle Bed Reactors
CFD MODEL
• Multi-fluid Model (Eulerian-Eulerian)Continuity Equation
0=⋅∇+∂
∂KKK
KK Ut
ρερε
Momentum Balance Equation
( ) ( )RkRKKKK
KKKKKKKK
UUFgU
PUUtU
−++∇⋅∇
+∇−=⋅∇+∂
∂
,
)()(
ρεµε
ερερε
CFD Modeling of Trickle Bed Reactors
CFD MODEL
• Inter-phase Coupling Terms (Attou & Ferschneider, 2000)
( )⎟⎟
⎠
⎞
⎜⎜
⎝
⎛⎥⎦
⎤⎢⎣
⎡−
−−+⎥
⎦
⎤⎢⎣
⎡−
−=
333.0
2
667.0
22
21
)1()1(
)1()1(
G
L
pG
GLGP
G
L
pG
GGGL d
UUEd
EFε
εε
ερε
εε
εµε
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛⎥⎦
⎤⎢⎣
⎡−
−+⎥
⎦
⎤⎢⎣
⎡−
−=
333.0
2
667.0
22
21
)1()1(
)1()1(
G
S
pG
GGP
G
S
pG
GGGS d
UEd
EFε
εε
ερε
εε
εµε
⎟⎟⎠
⎞⎜⎜⎝
⎛+=
pL
SGP
pL
sLLS d
UEd
EFε
ερεµεε 2
22
21
CFD Modeling of Trickle Bed Reactors
CFD MODEL
• Capillary Terms
• Attou and Ferschneider (2000)
⎟⎟⎠
⎞⎜⎜⎝
⎛−=−
21
112dd
PP LG σ
⎟⎟⎠
⎞⎜⎜⎝
⎛⎟⎟⎠
⎞⎜⎜⎝
⎛⎟⎟⎠
⎞⎜⎜⎝
⎛−−
=−L
G
PGLG F
dPP
ρρ
εεσ 5416.0
112
333.0
( ) ⎟⎟⎠
⎞⎜⎜⎝
⎛⎟⎟⎠
⎞⎜⎜⎝
⎛
∂∂
⎟⎟⎠
⎞⎜⎜⎝
⎛
−+
∂∂
⎟⎟⎠
⎞⎜⎜⎝
⎛−⎟⎟
⎠
⎞⎜⎜⎝
⎛−
=∂∂
−∂∂
−
L
GG
G
ss
G
/
G
s
p
LG
ρρ
Fzε
εε
zε
εεε
d.σ
zP
zP
2
32
111
14165
32
CFD Modeling of Trickle Bed Reactors
CFD MODEL
• Capillary Terms
– Extent of Wetting, f (Jiang et al., 2002)
• Scalar Transport
iimiKKiKKKiKK SCDCU
tC
+∇⋅−∇=⋅∇+∂
∂ )( .ρερερε
cLG PfPP )1( −=−
025.01.881 <+=⎟⎟⎠
⎞⎜⎜⎝
⎛
L
G
L
G
L
G forFρρ
ρρ
ρρ
CFD Modeling of Trickle Bed Reactors
SIMULATED RESULTS
0
5
10
15
20
25
30
35
40
45
0 0.02 0.04 0.06 0.08 0.1
Velo city M agnitude, m/ sec
Non-prewetted Bed
Prewetted Bed
0
5
10
15
20
25
30
35
0 0.1 0.2 0.3Liquid Holdup
Non-prewetted BedPrewetted Bed
Pre-wetted Un-wetted
VL= 6 mm/ s, VG=0.22 m/ s, D=0.114 m, dP= 3 mm, σ=5%
Con
tour
s of
Liq
uid
Hol
d-up
Distributions within the bed
CFD Modeling of Trickle Bed Reactors
SIMULATED RESULTS
Column Diameter = 0.114 m Particle Diameter = 3 mm, VG=0.22 m/ s
CFD Modeling of Trickle Bed Reactors
SIMULATED RESULTS
VG= 0.22 m /s, D = 0.114 m VG= 0.22 m /s, D = 0.194 m
CFD Modeling of Trickle Bed Reactors
GAS-LIQUID FLOW IN TBR
• Estimation of Frictional Pressure Drop & Fraction of Liquid Supported by Gas
– Simulate at two values of ‘g’ (9.7, 9.9 m/s2)
21
12
21
ggLPg
LPg
LPf
−
⎟⎠⎞
⎜⎝⎛ ∆−⎟
⎠⎞
⎜⎝⎛ ∆
=⎟⎟⎠
⎞⎜⎜⎝
⎛ ∆
( )21L
12L gg
LP
LP
−ρ
⎟⎠⎞
⎜⎝⎛ ∆−⎟
⎠⎞
⎜⎝⎛ ∆
=φ
Fraction of Liquid Hold-up Supported by Gas Phase < 1
Solid
Liquid
Gas
( )
LL
Lf ρ
βφ
φ
≤
−⎟⎟⎠
⎞⎜⎜⎝
⎛ ∆=⎟
⎠⎞
⎜⎝⎛ ∆
Q
gLP
LP
LGLGL
CFD Modeling of Trickle Bed Reactors
SIMULATED RESULTS
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.00 0.20 0.40 0.60 0.80 1.00Liquid Flow Rate x10-1, kg/m2s
Liqu
id S
atur
atio
n a
ndL
Holub et. al. (1993) -Experimental dataSzady and Sundersan (1991)-Exp. DataCFD ResultsSupported Liquid Saturation
Calibrate Model Parameters from ∆P
Can Predict Total and Supported Liquid Volume Fraction
0
2
4
6
8
10
12
14
0.00 0.20 0.40 0.60 0.80 1.00Liquid Flow Rate x10-1, Kg/m2s
Pres
sure
Gra
dien
t KPa
/m
Saez and Corbonell (1985)-Exp. dataSzady and Sundersan (1991)-Increase in liquidSzady and Sundersan (1991)-decrease in liquidCFD Simulations w ithout Capillary ForceCFD Simulations
Operating conditions:VG=0.22m/s, D/dp =55, dp=3mm, Std. Dev.=5%, E1=215, E2=1.75
CFD Modeling of Trickle Bed Reactors
SIMULATED RESULTS
0
10
20
30
40
50
0 0.2 0.4 0.6 0.8 1Gas Flow Rate, (Kg/m2s)
Pres
sure
Dro
p, (K
Pa/m
) CFD ResultsExperimental Data
0
0.1
0.2
0.3
0.4
0.5
0 0.2 0.4 0.6 0.8 1Gas Mass Velocity, kg/m2s
Liqu
id S
atur
atio
n an
d L
Liquid Saturation- CFD ResultsSupported Liquid SaturationLiquid Saturation- Exp. Data
Data of Spachio & Baldi (1977)
As gas velocity increases, more & more liquid is
supported by gas
Operating conditions: VL=2.8x10-3 m/s, dp=3mm, D/dp=30, Std. Dev.=5%, E1=500, E2=3
CFD Modeling of Trickle Bed Reactors
SIMULATED RESULTS
0
0.04
0.08
0.12
0.16
0.2
0 2 4 6 8Gas mass velocity, Kg/m2s
Liqu
id S
atur
atio
n an
dL
Liquid Saturation- CFD ResultsSupported Liquid SaturationLiquid Saturation Exp. Data
0
40
80
120
160
200
0 2 4 6 8Gas Mass Velocity, (kg/m2s)
Pres
sure
Dro
p, (K
Pa/m
) Experimental DataCFD Results Data of Rao et al. (1983)
As gas velocity increases, more & more liquid is
supported by gas
Operating conditions:VL=1x10-3m/s, D/dp =15.4, dp=3mm, Std. Dev.=5%, E1=215, E2=3.4
CFD Modeling of Trickle Bed Reactors
RESIDENCE TIME DISTRIBUTION
0
0.02
0.04
0.06
0.08
0.1
0.12
0 20 40 60 80 100 120Time, (sec)
E(t),
sec
-1
Pre-wetted Bed
Non Pre-wetted Bed
Simulation Results
1
1
1
Experimental Results2
2
2
Operating conditions: VL=2.06x10-3m/s VG=0.22m/s, D/dp =18, dp=6mm, Std. Dev.=5%, E1=180, E2=1.75
CFD Modeling of Trickle Bed Reactors
MODELING OF HYDRO-PROCESSING REACTOR
• Reaction and Kinetics (Chowdhury et al. 2002)Hydro-desulfurisation (HDS)
SH,LAd
6.1S,L
56.0H,L
HDS2
2
cK1cck
r+
−=SHArH2SAr 22 +→+−
De-aromatisation of Mono-, Di- and Poly- Aromatics
NaphMono_MonoMonoMono CkCkr +−=NapthenesH3ArMono 2 ⇔+−
MonoDi_DiDiDi CkCkr +−=ArMonoH2ArDi 2 −⇔+−
DiPoly_PolyPolyPoly CkCkr +−=ArDiHArTri 2 −⇔+−
CFD Modeling of Trickle Bed Reactors
SIMPLIFICATIONS/ ASSUMPTIONS
• Pressure drop is insignificant compared to the operating
pressure
• Trickle bed reactor is operated isothermally (efficient heat
transfer)
• Ideal gas law is applicable
• Liquid phase reactants are non-volatile (negligible vapor
pressure)
• Gas-liquid mass transfer is the limiting resistance.
• The catalyst particles are completely wetted
CFD Modeling of Trickle Bed Reactors
MODEL EQUATIONS
• Mass Balance of Species i
• Source Terms for Gas Phase
• Source Terms for Liquid Phase
( ) ( ) kikkikmikkikkkkikkk SCDCU
tC
,,,.,, ρερερε
ρε+∇−=⋅∇+
∂∂
⎥⎦
⎤⎢⎣
⎡−−= Li
i
GiGLGLii C
HC
aKS
∑=
=
+⎥⎦
⎤⎢⎣
⎡−=
nrj
1jijB rηρLi
i
GiGLGLii C
HC
aKS
∑=
=
=nrj
1jijB rηρiS
CFD Modeling of Trickle Bed Reactors
MODEL EQUATIONS
• Mass Transfer Coefficient (From Goto & Smith, 1975)
• Solubility of Hydrogen/ H2S (Korsten et al. 1996)
2/1
1
2
⎟⎟⎠
⎞⎜⎜⎝
⎛⎟⎟⎠
⎞⎜⎜⎝
⎛= L
iL
L
L
LLi
LLi
DG
Dak
ρµ
µα
α
Li
NiH ρλ
υ.
=
220
42
320
210H1.aTaTaTaa
2 ρ++
ρ++=λ
).008470.03670.3exp(2
TSH −=λ835783.0a
1094593.1a
1007539.3a
1042947.0a
559729.0a
4
63
32
31
0
=×=
×=
×−=
−=
−
−
−
: molar gas volumeNυ
CFD Modeling of Trickle Bed Reactors
CASE STUDIES
• Gas and Liquid Superficial Velocities Increase with Scale
• Wetting gets Better with Scale
Parameters Laboratory Scale Reactor(Chowdhury et al. 2002)
Commercial Scale Reactor(Bhaskar et al. 2004)
Reactor Diameter, mBed Length
Particle Diameter, mBed Porosity
LHSV, h-1Operating Pressure, MpaOperating Temperature, K
Initial H2S Conc., v/v %
0.0190.5 m0.00240.50
1-520-28
573-693 0.5-8
3.816 m
0.00150.36
1-520-80
573-693 0.5-8
CFD Modeling of Trickle Bed Reactors
KINETICS/ OIL COMPOSITION
• From Chowdhury et al. (2002)
AdK
Kinetic Constants Values
, m3/kmol 50000
K, Dimensionless 2.5 X 1012 exp(-19384/T)
k*mono, m3/kg.s 6.04 X 102 exp(-12414/T)
k*Di, m3/kg.s 8.5 X 102 exp(-12140/T)
k*poly, m3/kg.s 2.66 X 105 exp(-15170/T)
Component Percentage
Ar-S % 1.67
Poly-Ar % 2.59
Di-Ar % 8.77
Mono-Ar % 17.96
Naphthenes % 19.25
CFD Modeling of Trickle Bed Reactors
SIMULATED RESULTS-1
Temperature Initial Concentration of H2S
0
25
50
75
100
573 583 593 603 613 623 633 643 653
Temp, K
Con
vers
ion,
Ar-
S %
Varying Porosity
Uniform Porosity
Ar-S Exp
0
30
60
90
0 2 4 6 8
Initial H2S Conc Gas Phase ( %, V/V)
Conv
ersi
on, x
(P=4 MPa, LHSV=2.0 h-1, QGNTP/QL=200 m3/m3, TR=320oC, yH2S=1.4% )Symbols denote experimental data of Chowdhury et al. (2002)
CFD Modeling of Trickle Bed Reactors
SIMULATED RESULTS-2
(P=4 MPa, LHSV=2.0 h-1, QGNTP/QL=200 m3/m3, yH2S=1.4%)Symbols denote experimental data of Chowdhury et al. (2002)
0
10
20
30
40
50
60
70
80
90
573 593 613 633 653Temperature, K
Con
vers
ion,
%
Ar-Ptotaltotalpoly
0
10
20
30
40
50
60
573 593 613 633 653Temperature, K
Con
vers
ion,
%
Ar-D
Ar-M
Ar-Di-Expt
Ar-Mono-Exp
CFD Modeling of Trickle Bed Reactors
SIMULATED RESULTS-3
0
10
20
30
40
50
60
2 2.4 2.8 3.2 3.6 4
LHSV, h-1
Con
vers
ion,
%
Total-ArAr-Poly
Ar-DiAr-Mono
(P=4 MPa, TR=320 oC, QGNTP/QL=200 m3/m3, yH2S=1.4%, filled symbols are for experimental data of Chowdhury et al., 2002)
CFD Modeling of Trickle Bed Reactors
INFLUENCE OF REACTOR SCALE
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.2 0.4 0.6 0.8 1
Dimensionless Radius
Dim
ensi
onle
ss S
olid
Hol
d-up
0
5
10
15
20
25
30
35
Dim
ensi
onle
ss L
ocal
Axi
al V
eloc
ity
Solid hold-upLocal Axial Velocity
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.2 0.4 0.6 0.8 1
Dimensionless RadiusD
imen
sion
less
Sol
id H
old-
up
0
1
2
3
4
5
6
7
Dim
ensi
onle
ss L
ocal
Axi
al V
eloc
ity
Solid hold-upLocal Axial Velocity
Industrial (LHSV=2)Laboratory (LHSV=3)
(P=4 MPa, TR=320 oC, QGNTP/QL=300 m3/m3)
CFD Modeling of Trickle Bed Reactors
INFLUENCE OF REACTOR SCALE
25
50
75
100
573 593 613 633 653
Temperature, K
Con
vers
ion,
% Lab-scale ReactorCommercial Reactor
0
2000
4000
6000
8000
10000
12000
573 593 613 633 653Temperature, K
Out
let C
onc.
Ar-
S, p
pm
Lab Scale Reactor
Commercial Reactor
(Plab & com=4 & 4.4 MPa, LHSVlab=2.0 h-1, QGNTP/QL=200 m3/m3, yH2S=1.4%)
CFD Modeling of Trickle Bed Reactors
INFLUENCE OF REACTOR SCALE
-20
0
20
40
60
80
100
573 593 613 633 653Temperature, K
Con
vers
ion,
%
Poly-ArTotalPoly-Ar-CommercialTotal-Commercial
505560
6570758085
9095
100
2 2.5 3 3.5 4LHSV, h-1
Con
vers
ion,
%
Ar-S-Lab Scale
Ar-S-Commercial
(Plab & com=4 & 4.4 MPa, LHSVlab & com=2.0 & 3.0 h-1, (QGNTP/QL)lab & com= 200 & 300 m3/m3, yH2S=1.4%)
(Plab & com=4 & 4.4 MPa, Temperature= 593 K,(QGNTP/QL)lab & com= 200 & 300 m3/m3, yH2S=1.4%)
CFD Modeling of Trickle Bed Reactors
INFLUENCE OF REACTOR SCALE
0
20
40
60
80
100
120
2 3 4 5 6 7 8
Pressure, MPa
Con
vers
ion,
%
Poly-Ar
Di-Ar
Mono-Ar
Total
0
10
20
30
40
50
60
70
80
90
100
2 2.5 3 3.5 4LHSV, h-1
Con
vers
ion,
%
Poly-ArDi-ArMono-ArTotal
(QGNTP/QL)lab & com= 200 & 300 m3/m3 T=593 KLHSVlab & com=2.0 & 3.0 h-1 ,yH2S=1.4%
Plab & com=4 & 4.4 Mpa, T=593 K yH2S=1.4%(QGNTP/QL)lab & com= 200 & 300 m3/m3
Continuous lines: commercial; Dotted lines: laboratory scale
CFD Modeling of Trickle Bed Reactors
CONCLUDING REMARKS
• Macroscopic CFD Model Reasonably Simulates Gas-liquid Flow in Trickle Beds– Liquid hold-up– Residence time distribution– May be used to estimate fraction of suspended liquid
• Further Work is Needed for Understanding Wetting/ Hysteresis to Make Further Progress
• Despite Limitations, CFD Models can be Used to Understand Key Issues in Reactor Engineering Including Scale-up & Scale-down
CFD Modeling of Trickle Bed Reactors
CFD Modeling of Trickle Bed Reactors
MODELING OF MESO-SCALE FLOWS
• Single Phase Flow through Packed Bed– Unit cell approach– Simple cubic, FCC, rhombohedral ..– Inertial flow structures, pressure drop, heat transfer
• Interaction of Liquid Drop/ Film with Solid Surface– Regimes of interaction– Dynamic contact angle/ surface characteristics– VOF simulations– Insight into capillary forces???
CFD Modeling of Trickle Bed Reactors
SINGLE PHASE FLOW
• Single Phase Flow through Packed BedPeriodic Flow
Wall
Wall
Periodic Flow
Wall
Operating Parameters• Cell Length 28mm, 3mm• Fluid Water• Particle Reynolds Number 12-6000
CFD Modeling of Trickle Bed Reactors
SINGLE PHASE FLOW
Experiments:Suekane et al. AIChE J., 49, 1
Simulations
0
5
0
4.5
CFD Modeling of Trickle Bed Reactors
SINGLE PHASE FLOW
0
1
2
3
-1 -0.5 0 0.5 1x/r
Vz/V
mea
n
Experimental
Simulat ion-28mm
Simulat ion-3mm
-1
0
1
2
3
4
-1 -0.5 0 0.5 1x/r
Vz/V
mea
n
Experimental
Simulat ion-28mm
Simulat ion-3mm
-1
0
1
2
3
4
5
-1 -0.5 0 0.5 1x/r
Vz/V
mea
n
Experimental
Simulat ion-28mm
Simulat ion-3mm
-1
0
1
2
3
4
5
-1 -0.5 0 0.5 1x/r
Vz/V
mea
n
Experimental
Simulat ion-28mm
Simulat ion-3mm
CFD Modeling of Trickle Bed Reactors
SINGLE PHASE FLOW
E
S
Vz=8.66mm/s
Max arrow length :A=0.26 mm/sB=0.29 mm/sC=0.44 mm/s
A: z/r=0.14 (experimental) B: z/r=0.28 (experimental) C: z/r=0.42 (experimental)A: z/r=0.14 (experimental) B: z/r=0.28 (experimental) C: z/r=0.42 (experimental)A: z/r=0.14 (experimental)A: z/r=0.14 (experimental) B: z/r=0.28 (experimental)B: z/r=0.28 (experimental) C: z/r=0.42 (experimental)C: z/r=0.42 (experimental)
CFD Modeling of Trickle Bed Reactors
SINGLE PHASE FLOW
• Inertial Flow Structures were Captured Accurately by CFD Models
• Velocity Distribution in Unit Cells Resembles that in a Packed Bed
• Ergun Parameters may be Obtained through Unit Cell Approach for Semi-structured Packed Bed
• Unit Cell Approach may be Extended to Simulate Two Phase Flows to Understand Wetting
CFD Modeling of Trickle Bed Reactors
LIQUID SPREADING ON SOLID SURFACES
Computer
CCD Camera
Monitor
Light Diffuser
Light
Drop Flow Over Pellet
Drop Rest on Flat Plate
8.79mm
1mm
φ10.4mm
CFD Modeling of Trickle Bed Reactors
DROP IMPACT ON SOLID SURFACE
CFD Modeling of Trickle Bed Reactors
DROP IMPACT ON SOLID SURFACE
CFD Modeling of Trickle Bed Reactors
FLAT SURFACE
(f)(c)
(d)
(e)(b)
(a)
t=0ms
t=16ms
t=20ms
t=36ms
t=48ms
t=240ms
t=0ms
t=10ms
t=210mst=25ms
t=45ms
t=45ms
CFD Modeling of Trickle Bed Reactors
DYNAMICS OF DROP IMPACT
CFD Modeling of Trickle Bed Reactors
MODELS FOR INTERPHASE COUPLING?
Wall Shear Stress on Solid Surface, red~100 Pa
Drop Shape at 12 ms
Shear Strain on Gas-liquid Interface
Recommended