Packing CharacterizationMass Transfer Properties
Chao Wang
Carbon Management Project of PSTC
Advisors: Gary Rochelle and Frank Seibert
Research Engineer: Micah Perry
6th Trondheim CCS Conference
June 15, 2011
Mass Transfer in a Typical CO2 Capture Process
kGa
kGa
a
kLa
H CO 2
1
1
1 ∆PCO 2 *
(
)
=
+
+
KG a
kG a a k 2 [ Am]DCO 2
kl a ∆cCO 2
Research objective
• ae—effective gas-liquid contact area--CO2
capture absorber
• kGa–gas film mass transfer coefficient– water
wash, gas cooler
• kLa– liquid film mass transfer coefficient–
stripper
• Objective: -measure ae, kG and kL for novel
structured and random packings
•
- develop a fundamental model can
predict ae, kG and kL for novel packings.
Packed Column
ID:0.43m
Packing Information
Packing
Name
RSP 250
Type
Hybrid
Surface
Area
(m2/m3)
250
FP 1.6 Y
HC
Mellapak
2X
RSR #0.5
250
High
Capacity
60° angle
295
205
Random
metal
1” Plastic
Pall Ring
Random
plastic
210
Corrugatio
n Angle
N/A
45
60
N/A
N/A
N/A
0.017
0.02
N/A
N/A
Void
fraction, ε
0.92
0.95
0.99
N/A
N/A
Channel
Side, S (m)
Effective gas-liquid contact area
• Absorption of CO2 into 0.1 N NaOH solution
• Pseudo first order reaction
• Liquid phase control
ae =
yCO2in
)
uG ln(
yCO2out
k g' =
ZKG RT
≈
yCO2in
)
uG ln(
yCO2out
ZkG' RT
kOH − [OH − ]DCO 2, L
H CO 2
Gas-liquid contact area of MP2X
Fractional Area, ae/ap
1.2
uG = 4.87 ft/s
uG = 3.25 ft/s
uG = 1.95 ft/s
ae/ap= 0.70L0.125
1.0
0.8
0.6
0
10
20
Liquid Load, GPM/ft2
30
Tsai’s area model (Tsai,2010)
1,3
1,2
Fractional area, ae/ap
1,1
 ρ L 1/ 3 L 4 3 
ae
= 1.34 ( ) g ( ) 
ap
aP 
 σ
0.116
+13%
1
0,9
0,8
-13%
0,7
9 structured
packings
ap: 125 – 500 m2/m3
μL: 1 – 15 mPa·s
σ: 30 – 72 mN/m
0,6
0,5
0,4
0,0001
0,001
0,01
 ρ L  13  L 
 g  
 σ   ap 
4
0,1
3
Tsai R. "Mass Transfer Area of Structured Packing". The University of Texas at Austin. Ph.D
Dissertation. 2010
Gas-liquid contact area
Fractional Effective Area ae/aP
1.4
+20%
1.2
1
RSP250
(Hybrid)
-20%
RSR#0.5
(60 angle)
Tsai area
(High Capacity)
0.8
0.6
MP2X
FP1.6YHC
1"PPR
(Plastic Random)
(Metal Random)
0.4
5.0E-6
1.0E-5
2.0E-5
4.0E-5
8.0E-5
Generalized Liquid Superficial Velocity uL/aP (m2/s)
Gas Film Mass Transfer Coefficient
• Gas film control (SO2/NaOH solution system)
• Instantaneous reaction
• Liquid film resistance can be neglected
yin
uG ln(
)
yout
kG a =
ZRT
kG a
k G=
ae
• SO2 concentration is measured by two different range
SO2 analyzers. Outlet sample SO2 analyzer can detect
can use 10 feet packing
0.1 ppb SO2
Gas film mass transfer coefficient kG of MP2X
5.0 GPM/ft2
kG = 0.026uG0.77
10.0 GPM/ft2
0.12
20.0 GPM/ft2
kG, ft/s
0.08
0.04
0.00
0
2
4
6
Gas Velocity, ft/s
8
kG summary
kG/(m/s)
0.04
1"PPR
n=0.87
RSR#0.5
n=0.96
RSP250
n=0.8
MP2X
n=0.73
0.02
FP1.6YHC
n=1.05
0.01
kG=kG,uG=1m/s*(uG/1)n
0.005
0.5
1
Gas Superficial Velocity uG (m/s)
2
Modified Rocha-Bravo-Fair1 kG Model
kG S
(uGE + u LE ) ρ G S 0.8 µG 0.33
= 0.054(
) (
)
DG
µG
DG ρ G
(uGE + uLE ) ρ G 0.88 µG 0.33
kG
= 0.032(
) (
)
aP DG
aP µG
ρ G DG
uGE
uGS
=
ε (1 − hL ) sin θ
1.Rocha JA, Bravo JL, Fair, JR. “Distillation Columns Containing Structured Packings:
A Comprehensive Model for Their Performance.2. Mass-Transfer Model.” Ind Eng
Chem Res. 1996;35:1660–1667.
kG model
16
MP2X
+20%
FP1.6YHC
-20%
RSP250
ShG=kGdeq/DG
8
ShG=0.0317*ReG0.88ScG0.33
4
Average Deviation
16.2%
2
150
300
600
Re=uGEρGdeq/μG
Liquid film Mass Transfer Coefficient
• Liquid film control (Air/Toluene/Water system)
• No chemical reactions
• Mass transfer resistance mainly in liquid film
stripping:
•
uL
k L a = ln(cLin / cLout )
Z
kLa
k L=
ae
Liquid film mass transfer coefficient kL of MP2X
3E-4
uG = 4.87 ft/s
uG = 3.25 ft/s
uG = 1.95 ft/s
kL = 2E-05uL0.6809
kL, ft/s
2E-4
1E-4
0E+0
0
10
20
Liquid Load, GPM/ft2
30
kL summary
MP2X
n=0.70
kL/(m/s)
6E-5
3E-5
2E-5
1"PPR
n=0.63
RSR#0.5
n=0.81
FP1.6YHC
n=0.76
RSP250
n=0.71
kL=kL,uL=0.0067*(uL/0.0067)n
8E-6
5.0E-6
1.0E-5
2.0E-5
4.0E-5
8.0E-5
Generalized Liquid Superficial Velocity uL/aP (m2/s)
Brunazzi2 dimensionless kL model (1997)
Gz B
ShL = A C
Ka
Gz = Re L ScL
σ 3ρL
Ka = 4
µL g
A=409, B=0.5, C=0.09
δ sin θ
H el
δ =(
ρ L SU LE
Re L =
µL
U LS 0.5
3µ L
)
ρ L g sin θ hL sin θ
ScL =
µL
ρ L DL
uLE =
uLS
εhL sin θ
• Consider the mixing of liquid phase occurs at junctions.
Kapista number Ka
• Includes the flow path length factor, which is Hel/sinθ
• Includes packing geometry factor S, liquid film thickness
•
2.Brunazzi E, Paglianti A. "Liquid-Film Mass Transfer Coefficient in a column Equipped with
Structured Packings." Ind Eng Chem Res. 1997;36:3792-3799
kL model
1600
800
ShL=kLdeq/DL
+20%
MP2X
FP1.6YHC
RSP250
-20%
400
ShL=409*Gz0.5Ka-0.09
Average Deviation 20.2%
200
100
15
30
60
120
Gz=ReLScLδsinθ/Hel
240
480
Conclusions
• ae is a function of L, ~uL0.155, not a function of G ,
Tsai’s area model:
ae
ρ L 1 / 3 Q 1 4 / 3 0.116
= 1.42[( ) g ( * ) ]
ap
σ
A ap
• kG ~uG0.88, not a function of uL
0.88
0.33
Modified RBF kG model: ShG = 0.0317 * ReG ScG
• kL ~uL0.74, not a function of uG
Modified RBF kL model: ShL = 409 * Gz 0.5 Ka −0.09
Thank You
Chao Wang
[email protected]