Modeling Mass Transfer Performance of Packings · MellaPak ®, Montz-Pak ®, GT-Pak ... Billet....

Modeling Mass Transfer Performance of Packings

Di Song

Gary Rochelle & Frank Seibert

University of Texas at Austin

Contents

Introduction

Model of ae

Model of kL

Model of kG

Conclusions

2

• Mass transfer & Packings

• Why is µL important

• Methods & SRP database

• Scale-up: secondary area

• Effect of µL

• Scale up: packing height

• Effect of µL

• Significance of this work

• Recommendations

Contents

Introduction

Model of ae

Model of kL

Model of kG

Conclusions

3





• Effect of µL


• Effect of µL


• Recommendations

Two-film theory 4

CO2

Bulk liquidLiquid filmGas filmBulk gas

PCO2Pi

CO2

[CO2]i

[CO2] or P*CO2

Rxn. film

5Two-film theory

6Two-film theory

7Two-film theory

8Two-film theory

9Two-film theory

Packings 10

Random Structured Hybrid

Since 1890s 1960s >2000

Cost Low High High

Efficiency Moderate High High

Capacity Moderate High Medium

Shape

Mass transfer in amine capture process

11

Flue Gas

DCC (kGae)Absorber(kL & ae)

WW(kGae)

Stripper (kLae)

C Free Gas

CO2 for Compr.

Amine

Mass transfer in amine capture process

12

Flue Gas

DCC (kGae)Absorber(kL & ae)

WW(kGae)

Stripper (kLae)

C Free Gas

CO2 for Compr.

Amine

Reliable packing model is critical for design

μL is critical to solvent selection

• Heat transfer

• h Q

• Mass transfer

• Diffusion of CO2 through reactive layer

• Diffusion of free amine to L-G interface (surface depletion)

• Diffusion of loaded amine back to bulk liquid (P*CO2)

• Liquid turbulence

13

µSolvent ≫ µH2O

14

Amine soln.(α = 0.4) H2O 7m MEA 11m MEA 5m PZ 8m PZ

μ @ 40 ̊C(cP) 0.65 2.4 4.0 3.6 11.4

Water lean solvent.

Alkylcarbonates: IPADM-BOL

Switchable Carbamates:

TESA

Aminosilicones: GAP-0/TEG

Nonaqueous organic amine blends: AMP/PZ + EGME + 15 wt % H2O

μ @ 40 ̊C(cP) ~ 130 cP ~800 cP ~1300 cP ~30 cP

μL affects kL in two ways (how much?)15

• α – Direct influence via the turbulence of liquid

• βγ – Indirect influence via D of mass transfer species

kL = C1· μα·Dβ

D = C2· μγkL (kLa) = C3· μα+βγ

μL affects ae?

Pilot packed column16

Blower180-450 ACFM

Storage Tank250 gal

Pump 2.5-30 gpm/ft2

Liquid Outlet

Liquid Inlet

Bypass

Air Inlet

Air Outlet

H: 25 ftZmax: 10 ft

I.D.: 16.8 in

F40 DistributorTrutna Collector

Chemical systems17

• kG: Trace SO2/NaOH/H2O

• kL: Air/Toluene/H2O

• ae: Ambient CO2/NaOH/H2O

Chemical systems18



• ae: Ambient CO2/NaOH/H2O + glycerol

+ glycerol (1–70 cP)

Chemical systems19



• ae: Ambient CO2/NaOH/H2O

Kinetic model based on WWC exp.

+ glycerol

+ glycerol (1–70 cP)

SRP database20

• 21 Structured Packings

MellaPak®, Montz-Pak®, GT-Pak®, Flexipac®, etc

• 12 Random Packings

Pall Ring, IMTP®, Raschig-SuperRing®, etc

• 4 Hybrid Packings

Raschig-SuperPak®, Hiflow Plus®

• 1 Gauze Packing

Contents

Introduction

Model of ae

Model of kL

Model of kG

Conclusions

21





• Effect of µL


• Effect of µL


• Recommendations

Effective mass transfer area: ae22

0

100

200

300

400

500

0 100 200 300 400 500

a e,to

tal(

m2 /

m3 )

aP (m2/m3)

Plastic

Fractional area Φ = 1

M 252Y

M 250YS

Gauze

Structured YStructured X/ZRandomHybrid

Secondary ae

23

Gas

Liquid

5 in.

10 ft.

6 ft.

Secondary ae

24

aWall

aTop

Gas

Liquid

5 in.

10 ft.

6 ft.

aBot

aSecondary = aTop + aWall + aBot

aTotal = ae,packing + aSecondary

Sec. ae is critical to scaling up25

0%

5%

10%

15%

20%

5 10 20 40 80 160

Ratio

to to

tal a

rea

DColumn (in)

Wall area

Bottom area

Top area

Avg. value @ G = 300 ACFM, L = 10, 15, 20 gpm/ft2

M 250Y (10 ft)

M 250Y

ae Model26

𝑎𝑎𝑒𝑒,𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝

𝑎𝑎𝑃𝑃= 1.16 � 𝜂𝜂 � 𝑊𝑊𝑊𝑊 � 𝐹𝐹𝐹𝐹−

120.138

= 1.16 � 𝜂𝜂𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡 � 𝜂𝜂𝑚𝑚𝑎𝑎𝑡𝑡𝑡𝑡𝑚𝑚𝑚𝑚𝑎𝑎𝑚𝑚 � 𝜂𝜂𝑚𝑚𝑙𝑙𝑎𝑎𝑙𝑙𝑚𝑚𝑙𝑙𝑙𝑙 �𝜌𝜌𝐿𝐿𝜎𝜎

� 𝑔𝑔 ⁄1 2 � 𝑢𝑢𝐿𝐿 � 𝑎𝑎𝑃𝑃⁄−3 2

0.138� 𝜇𝜇𝐿𝐿0

ae Model27

𝑎𝑎𝑒𝑒,𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝


120.138

= 1.16 � 𝜂𝜂𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡 � 𝜂𝜂𝑚𝑚𝑎𝑎𝑡𝑡𝑡𝑡𝑚𝑚𝑚𝑚𝑎𝑎𝑚𝑚 � 𝜂𝜂𝑚𝑚𝑙𝑙𝑎𝑎𝑙𝑙𝑚𝑚𝑙𝑙𝑙𝑙 �𝜌𝜌𝐿𝐿𝜎𝜎

� 𝑔𝑔 ⁄1 2 � 𝑢𝑢𝐿𝐿 � 𝑎𝑎𝑃𝑃⁄−3 2

0.138� 𝜇𝜇𝐿𝐿0

Random/hybrid:

𝜂𝜂𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡 = 1.34 − 0.26𝑎𝑎𝑃𝑃

250 Plastic:𝜂𝜂𝑚𝑚𝑎𝑎𝑡𝑡𝑡𝑡𝑚𝑚𝑚𝑚𝑎𝑎𝑚𝑚 = 0.62

Loading zone (ΔP ≥ 400 Pa/m):𝜂𝜂𝑚𝑚𝑙𝑙𝑎𝑎𝑙𝑙𝑚𝑚𝑙𝑙𝑙𝑙 = 1.15

28

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

50 100 150 200 250 300 350 400

Calc

ulat

ed/m

easu

red

a e,to

tal

Measured ae,total (m2/m3)

-20%

+20%

σ~72 mN/m, µ~1 cP

G = 300 ACFM

AAD = 8.9%

ae Model

ae model w/ viscosity 29

-20%

-10%

0%

10%

20%

0.5 2 8 32

Rela

tive

erro

r

µL (cp)


PEG (Tsai)

Glycerol

Contents

Introduction

Model of ae

Model of kL

Model of kG

Conclusions

30





• Effect of µL


• Effect of µL


• Recommendations

Liquid film mass transfer coefficient: kL31

1

2

3

4

5

0 100 200 300 400 500

avg.

k L·µ0.

4 /D0.

5

aP (m2/m3)



Liquid film mass transfer coefficient: kL32

1

2

3

4

5

0 100 200 300 400 500

avg.

k L·µ0.

4 /D0.

5

aP (m2/m3)



GTP 350 Y/Z

M 250 X/Y

Scaling packing height (kL)33

0

1

2

3

4

5

0 1 2 3 4 5

k L·µL0.

4 /D0.

5(6

ftpa

ckin

g)

kL·µL0.4/D0.5 (10 ft packing)


0

1

2

3

4

5

0 1 2 3 4 5

k L·µL0.

4 /D0.

5(6

ftpa

ckin

g)


6-10 ft Ratio

Structured 1.29

Hybrid 1.39

Random 1.54

Overall 1.32


0

1

2

3

4

5

0 1 2 3 4 5

k L·µL0.

4 /D0.

5(6

ftpa

ckin

g)


6-10 ft Ratio

Structured 1.29

Hybrid 1.39

Random 1.54

Overall 1.32

Maldistribution is worse for taller bed

Correction = ln ⁄1.32 1ln ⁄6 10

= −0.54

kL Model36

𝑆𝑆𝑆𝐿𝐿 = 0.12 � 𝑆𝑆𝑆𝑆𝐿𝐿0.5 � 𝑅𝑅𝑊𝑊𝐿𝐿0.565 � 𝐺𝐺𝑎𝑎𝐿𝐿⁄1 6 �

𝑍𝑍1.8

−0.54

𝑘𝑘𝐿𝐿 = 0.12 � 𝑢𝑢𝐿𝐿0.565 �𝜇𝜇𝐿𝐿𝜌𝜌𝐿𝐿

−0.4

� 𝐷𝐷𝐿𝐿0.5 � 𝑔𝑔 ⁄1 6 � 𝑎𝑎𝑃𝑃−0.065 �𝑍𝑍

1.8

−0.54

Dependence on µL of kL37

1.E-06

1.E-05

1.E-04

0.5 5 50

k L·aP0.

065 /

(uL0.

565 ·g

1/6 ·ρ

L0.4 )

µL (cP)

Hybrid

Structured

Random

-0.75 predicted in model

G = 300 ACFM

Dependence on µL of kL38

1.E-06

1.E-05

1.E-04

0.5 5 50

k L·aP0.

065 /

(uL0.

565 ·g

1/6 ·ρ

L0.4 )

µL (cP)

Hybrid

Structured

Random

-0.75 predicted in model

G = 300 ACFM

Direct = -0.40

Indirect = -0.35

Universally applicable

System-specific based on D-µ relationship

Comparison to other work: µL39

-100%

0%

100%

200%

300%

400%

500%

0.5 1 2 4 8 16 32 64

Rela

tive

erro

r = (k

Lam

odel

-kLa

exp)

/kLa

exp

µL (cP)

This work

Billet

Rocha

DelftValenz

M 250Y

Contents

Introduction

Model of ae

Model of kL

Model of kG

Conclusions

40





• Effect of µL


• Effect of µL


• Recommendations

Gas film mass transfer coefficient: kG41

0

4

8

12

0 100 200 300 400 500

avg.

k G/D0.

5

aP (m2/m3)

Avg. value @ L = 15 gpm/ft2, G = 180, 300, 450 ACFM


Gas film mass transfer coefficient: kG42

0

4

8

12

0 100 200 300 400 500

avg.

k G/D0.

5

aP (m2/m3)

Avg. value @ L = 15 gpm/ft2, G = 180, 300, 450 ACFM


GTP 350 Y/Z

M 250 X/Y

Model of kG43

𝑆𝑆𝑆𝐺𝐺 = 0.28 � 𝑆𝑆𝑆𝑆𝐺𝐺0.5 � 𝑅𝑅𝑊𝑊𝐺𝐺0.62 �sin 2𝛼𝛼

sin 2 × 45°

0.65

𝑘𝑘𝐺𝐺 = 0.28 � 𝑢𝑢𝐺𝐺0.62 �𝜇𝜇𝐺𝐺𝜌𝜌𝐺𝐺

−0.12

� 𝐷𝐷𝐺𝐺0.5 � 𝑎𝑎𝑃𝑃0.38 � sin 2𝛼𝛼 0.65

aeffective = 45° (for random/hybrid packings)

Finer packings are more controlled by kL44

0.001

0.002

0.004

0.008

50 100 200 400

Avg.

kL/

k G@

25

°C

aP (m2/m3)

Baseline: σ ~ 72 mN/m, µ ~ 1 cP


Contents

Introduction

Model of ae

Model of kL

Model of kG

Conclusions

45





• Effect of µL


• Effect of µL


• Recommendations

Significance of this work46

• Reliable & simple mass transfer models

• Large database & column size, variance of µL

• No packing-specific parameter

•

•

•

𝑎𝑎𝑡𝑡,𝑡𝑡𝑎𝑎𝑝𝑝𝑝𝑝𝑚𝑚𝑙𝑙𝑙𝑙


120.138

𝑆𝑆𝑆𝐿𝐿 = 0.12 � 𝑆𝑆𝑆𝑆𝐿𝐿0.5 � 𝑅𝑅𝑊𝑊𝐿𝐿0.565 � 𝐺𝐺𝑎𝑎𝐿𝐿⁄1 6 �

𝑍𝑍1.8

−0.54

𝑆𝑆𝑆𝐺𝐺 = 0.28 � 𝑆𝑆𝑆𝑆𝐺𝐺0.5 � 𝑅𝑅𝑊𝑊𝐺𝐺0.62 � sin 2𝛼𝛼 0.65

• Selection of packing

• aP, α, material, type

• Selection of solvent

• µL, σ, ρL

• Selection of operating condition

• L, G

• Scale-up of column design

• Secondary effect, liquid maldistribution

Conclusions

kL ∝ µL-0.75 (-0.4 & -0.35)

ae ≠ f (µL)

All types of packings have similar behavior in ΔµL

Z (or L/D) may strongly affect mass transfer

47

Recommendations

Avoid finest packings

Use low µL solvent

Use reliable models (developed in this work)

Thanks!

48

University of Texas at Austin

Di Song (Graduating 10/2017)

[email protected]

512-750-1480

mailto:[email protected]

Modeling Mass Transfer Performance of Packings · MellaPak ®, Montz-Pak ®, GT-Pak ... Billet....

Documents

Transcript of Modeling Mass Transfer Performance of Packings · MellaPak ®, Montz-Pak ®, GT-Pak ... Billet....