catalycatalytic distillationtic distillation - · pdf fileintegration of unit operations in...

Modern Methods in Heterogeneous Catalysis ResearchFritz Haber Institute, Berlin, 14 November 2003

Kai Sundmacher1,2

1 Max-Planck-Institute for Dynamics of Complex Technical Systems Sandtorstraße 1, 39106 Magdeburg, Germany

2 Otto-von-Guericke-University Magdeburg, Process Systems Engineering Universitätsplatz 2, 39106 Magdeburg, Germany

[email protected]

Catalytic DistillationCatalytic Distillation

Catalytic Distillation (CD) - Outline


4 Modelling, Simulation,Experimental Validation

CD Expert !

3 Catalysts for Usein CD Processes

2 Fields of Application,Process Examples

5 Operational ProcessBehaviour

1 Basic Principles of CD

CD Lecture

Integration of Unit Operations in Multifunctional Reactors

Physical Unit

Operations

Chemical/Biological

Units

Raw Materials

SeparationUnits for

Reactants

By-Products

SeparationUnits for

By-Products

Main Products

MultifunctionalReactors (e.g. Reactive Mill)

Multifunctional Reactors(Reactive Distillation / Absorption / Extraction / Adsorption Column)

MultifunctionalReactors (e.g. Fuel Cells)

Recycle

Possible Benefits from Multifunctional Reactor Concepts

Synergetic interactions of chemical and physical unit operations may lead to:

á increase of productivity from process intensification

á increase of selectivity of reactions and/or separations

á reduction of by-products and waste materials

á more efficient (in situ) use of energy

á inherent safety

á improved environmental compatibility (e.g. by avoidance of hazardous solvents etc.).

Design Variables:- Damköhler Number - Number of Stages N- Product Quality x2

D = X

Operational Variables:- Reflux Ratio - Recycle Ratio

Thermodynamic Parameters:- equilibrium constant K- relative volatility

Kinetic Parameters: - reaction order n- rate constant k

FkVDa R≡

12 / KK≡α

FB /≡ϕDLR /≡

−=

1

21

11 xx

Kxkr n

Reactor-Separator System for Isomerization A1 ⇔ A2

CSTR

B

DistillationColumnF, x1

F = 1

D, x2DL

VRVR N

( ) 2

22 11

x

xy−+

=αα

Reaction Kinetics: Vapour-Liquid-Equil.:

A1 A2

A2

A1

here

Qi, Z., Sundmacher, K. (2000) Chem. Eng. Process, in preparation.

0 2 4 6 8 1010

15

20

25 X = 0.99R K = 2, α = 1.5n = 1

ϕ = 10

ϕ =

ϕ = 5

ϕ = 2

Min

imum

Num

ber o

f Sta

ges,

N =

Nm

in

Damköhler Number, Da

Design for Reaction Order n = 1

ϕ = ∞

CSTR + Column on Top

∞

→ ∞

DistillationColumn

D, x2DL

VR

N

A2

CSTRFA1

Reactor-Separator System for Isomerization A1 ⇔ A2

Qi, Z., Sundmacher, K. (2000) Chem. Eng. Process, in preparation

Damköhler Number in CD Processes

FVkDa R⋅

≡

)( bappSitescat Tkck ε=

Damköhler numberfor first order reactions

catalystholdup

concentrationof active siteson catalyst

apparentrateconstant

Boiling temperature

),( xpTT bb =

+ rate controlvia pressure !temperature

+ T is not a dynamic variable !

0,001 0,01 0,1 1 10 1000,0

0,2

0,4

0,6

0,8

1,0

50

510

12

20

N =100

α = 1.5 K = 2, n = 1R = 10

Con

vers

ion,

X

Da / N

Reactive Distillation Column Influence of Reaction / Separation

DL

N

F

R = L / D Xeq = 66.6 %

(CSTR)

NTSMcA

NFkV

NDa sitescatcR ε

∝=

TotalReboiler

Reaction / Separation:

420 0.2)20( === xNDaopt

X = 92.5 %

Reactive Distillation Column for Isomerization A1 ⇔ A2


ReactiveAzeotrope

2 4 6 8 10 12 14 16 18 200,70

0,75

0,80

0,85

0,90

0,95

1,00

1020

5

100

R = 1

2

α = 1.5 K = 2, n = 1N = 20Da = 4

Con

vers

ion,

X

Number of Catalytic Stages, Ncat

Influence of Catalyst DistributionHybrid Column with Catalytic Stages

DL

N = 20

F

R = L / D

TotalReboiler

Ncat

201918.......321

BaseCase

Design of Hybrid CD Column for Isomerization A1 ⇔ A2


Reactive Batch Distillation: MeOH + IA ⇔ TAME

Thiel, C.; Sundmacher, K.; Hoffmann, U. (1997) Chem. Eng. Sci. 52, 993-1005.

Heating policy:V / V0 = H / H0

Liquid phase:Holdup HComposition xi

MeOHL + IAL TAMEL

MeOHV IAV TAMEV

Qreb

Vapour phase:Vapour Flow VComposition yi

FCR

LCRH+

Catalyst: Acidic Ion Exchange Resin (Vcat, cH+)

( )( ) ( ) ( )d d

x x y x T Da x r x Tii i i iτ

ν ν= − + ⋅ − ⋅, ,*

1 244 344 1 24 34 123Separation by

DistillationReactionKinetics

Influence ofStoichiometry

Dak T c V

Vref sites cat

o≡⋅ ⋅+ ( )&

Damköhler Number Boiling Temperature

( )T T x p= ,


Reactive Batch Distillation: Model Equations

Mass Balances

p = 10 bar

2 stable nodes1 unstable node (azeotrope)1 saddle point (azeotrope)1 separatrix

Mol

e Fr

actio

nof

MeO

H

Mole Fraction IATAME IA

MeOH


Catalytic Batch Distillation for TAME-Synthesis: No Reaction (Da = 0)


p = 10 bar

3 stable nodes0 unstable nodes2 saddle points2 separaticdschemical equilibrium line

Mol

enbr

uch

Met

hano

l

Molenbruch IsoamylenTAME IA

MeOH

Catalytic Batch Distillation for TAME-Synthesis: Slow Reaction (Da = 10-4)

Mol

eFr

actio

nof

MeO

H

Mole Fraction of IA


Mole Fraction of IA TAME IA

MeOH2 stable nodes0 unstable nodes1 saddle point1 separatrixchemical equilibrium line

p = 10 bar

Catalytic Batch Distillation for TAME-Synthesis: Fast Reaction (Da = 10-3)

Mol

eFr

actio

nof

MeO

H

Mol

enbr

uch

Met

hano

l

Molenbruch IsoamylenTAME IA

MeOH2 stabile nodes0 unstable nodes1 saddle point1 separatixchemical equilibrium line

p = 10 bar


Catalytic Batch Distillation for TAME-Synthesis: Reaction in Equilibrium (Da > 1)

Mol

eFr

actio

nof

MeO

H

Mole Fraction of IA

Main Rxn 2 B ⇔ A + CSide Rxn 2 C → 2 D

αAC = 10αBC = 3αDC = 13

20 stages

9 stages

9 stages

Feed at

stage 20

Variationof Da on

stage

Keq = 0.25R = 3.8S = 5.3

Studies of Side Reactions: Influence of Stage Damköhler Number

( ) ( )2

2*

2

2*

51 1.0

51/

C

C

sideC

eqCA B

main x x r

x Kx - xx

r+

=+

=

A + D

C

B

0,01 0,1 10,0

0,2

0,4

0,6

0,8

1,0

Selectivity, S

Conversion, X

Stage Damköhler Number, Da

N = 38

5 stagesFeed at

stage 20

Da = 0.8 on stage

A + D

C

B

Studies of Side Reactions: Influence of Catalyst Position

Changing Positionof Catalyst

5 10 15 20 25 300,0

0,2

0,4

0,6

0,8

1,0Selectivity, S

Conversion, X

Position of Catalyst Section

N = 38

Main Rxn 2 B ⇔ A + CSide Rxn 2 C → 2 D

αAC = 10αBC = 3αDC = 13

Keq = 0.25R = 3.8S = 5.3

( ) ( )2

2*

2

2*

51 1.0

51/

C

C

sideC

eqCA B

main x x r

x Kx - xx

r+

=+

=

Studies of Side Reactions: Influence of Catalyst Position(Da = 0.2, Reactive Stages = 5)

A + D

C

B

A + D

C

B

40

35

30

25

20

15

10

5

0

0,0 0,2 0,4 0,6 0,8 1,0

xi

Sta

ge

DA

B

C

40

35

30

25

20

15

10

5

0

0,0 0,2 0,4 0,6 0,8 1,0

xi

Sta

ge

D A

B

C

A + D

C

B

A + D

C

B

2

2

*

* /~

C

eqCA B

side

main

xKx - xx

rr

Relative Volatility, αH2O/Ester

Low HighMedium

Fast

Slow

Rea

ctio

nR

ate,

r

see e.g.: Schoenmakers (1997)

Mapping of Reactor-Separator Systems for Esterification: Alcohol + Acid ⇔ Ester + H2O

RD System based on Pre- and Side Reactors

see e.g.: Aittamaa, J., Eilos, I., Jakkula, J., Lindqvist, P., US 5 637 777 (1997)

Advantagesl easy catalyst replacementl easy control of reactant-ratiol independent of specific

catalyst packingl distillation column hydraulics

and mass transfer notaffected by catalyst structure

l high Da/N-ratio achievableMeOH

CxHy

MeOH

Side-ReactorsPre-Reactors

Ether Production Flow Scheme (Neste Oy)

Simple Guideline for CD Reactor Selection

p Slow reactions: Da << 1

+ reaction kinetics is limiting+ high residence time+ hom. catalysis: high liquid holdup+ het. catalysis: high catalyst holdup

p Solution

+ tray column (bubble caps)+ packed column with random packing+ column with external side reactors

p Fast reactions: Da ≥ 1

+ mass transfer is limiting+ low residence time sufficient+ hom. catalysis: low liquid holdup+ het. catalysis: low catalyst holdup

p Solution

+ packed column+ tray column with low holdup

increase p



CD Expert !






CD Lecture

Motives for Application of Reactive Distillation

Motives Examples

Overcoming Limitations Methanol + Acetic Acid ⇔ Methyl Acetate + H2Oof Chemical Equilibrium Methanol + Isobutene ⇔ Methyl-tert.-butylether (MTBE)

Formaldehyde + 2 Methanol ⇔ Methylal + H2O

Increase of Chlorohydrins → Propylene Oxide + H2O → Proplene GlycolSelectivity 2 Acetone → Diacetone Alcohol → Mesityl Oxide + H2O

Isobutane + 1-Butene → Isooctane + 1-Butene → C12H24

Use of Heat Propene + Benzene → Cumeneof Reaction Ethylene Oxide + H2O → Ethylene Glycol

Separation of m-Xylene / p-Xylene (Reactive Entrainer: Na-p-Xylene)Closely Boiling Mixtures Cyclohexene / Cyclohexane (Reactive Entrainer: Formic Acid)

1-Butene / Isobutene (Reactive Entrainer: Methanol / Water)

Breaking of Methyl Acetate / Water ; Methyl Acetate / MethanolAzeotropes (Entrainer: Acetic Acid)

High Purity Hexamethylene Diamine / Water (in Nylon 6,6 process)Separation (Reactive Entrainer: Adipic Acid)

Rea

ctio

nP

robl

ems

Sep

arat

ion

Pro

blem

s

See e.g.: Sundmacher, K., Rihko, L., Hoffmann, U., Chem. Eng. Commun. 127 (1994) 151-167.

Production of Methyl Acetate

H+

Acetic Acid + Methanol MeAc + Water←→Reaction:

Catalysts: H2SO4 / Acidic Ion Exchange Resin

Chemical Equilibrium Constant: Kx(25°C) = 5.2

Boiling Sequence at p = 0.1 MPa:hom. azeotrope MeAc/Methanol 53.8 °Chom. azeotrope MeAc/Water 56.7 °CMethylacetate (MeAc) 56.9 °CMethanol 64.6 °C Water 100.0 °CAcetic Acid 118.0 °C

L/L-phase splitting: in ternary system MeAc/Methanol/Water

Acetic AcidMethanol

H2SO4 (Cat.)

Rea

ctor

MethylAcetate

High Boilers

Water +H2SO4

Ext

ract

ive

Dis

tilla

tion

Ext

ract

ion

Dis

tilla

tion

Aze

otro

pic

Dis

tilla

tion

Dis

tilla

tion

Dis

tilla

tion

Dis

tilla

tion

Dis

tilla

tion

PhaseSep.

WaterEthyleneGlycol

Acetic Acid

Methanol

Ethyl-acetate Water

Dis

tilla

tion

Production of Methyl Acetate (Conventional Process)

Homogeneously Catalyzed Reaction* Heterogeneously Catalyzed Reaction**

* Agreda, V.H.; Partin, L.R., US Patent No. 4,435,595 (1984, Eastman-Kodak-Process)**Bessling, B.; Löning, J.-M.; Ohligschläger, A.; Schembecker, G.; Sundmacher, K., Chem. Eng. Technol. 21 (1998) 393-400.

Methyl Acetate

Acetic Acid

Water

Methanol

Reactive Section (13 Stages,Ion Exchange Resin Packing)

RectifyingSection (6 Stages)

Stripping Section (6 Stages)

Methanol

Acetic Acid

Methyl Acetate

Water + H2SO4

H2SO4

(Catalyst)

Impurities

Return from Impurity removalColumns

Production of Methyl Acetate (CD Processes)

CD Application for Highly Exothermic ReactionsExample: Cumene Production

Shoemaker, J.D., Jones, E.M., Hydrocarbon Processing (1987) 57-58.

Reaction Scheme

l p = 3 - 10 bar, Tmax ≈ 250 °Cl Solid acid catalystl Reaction heat: (-∆RH) ≈ 113 kJ/moll By-product formation favored at higher T

Benzene

Cumene

Propylene

ReactiveZone

StrippingZone

Distillation

Vent (C3)

DIBP

CH3-CH-CH3

CH2=CH-CH3 +

Propylene Benzene

CH3-CH-CH3

+ CH2=CH-CH3

Cumene Propylene

DIPB

CH3-CH-CH3

CH3-CH-CH3

BenzeneDIPB

+

Cumene

2

CH3-CH-CH3

CH3-CH-CH3

CH3-CH-CH3

Cumene

FeedWash

MethanolExtraction

Methanol/Water

Distillation

Fixed BedTubularReactor

ReactiveDistillationColumn

see e.g.: anonymus, Hydrocarbon Processing 73 (1992) 104-110. * approx. 32 % market share

C4 (IB+Inerts)(Raffinate I)

Water

Methanol

Water +Impurities

Recycle Methanol

Nonreacted C4(Raffinate II)

Nonreacted C4 + Methanol

Water

MTBE

XIC4 ≈90 %

XIC4 ≈99.9 %

p = 5...10 bar

Kata-Max

RD Application for High Purity Separation,Example: C4-Separation (Hüls-UOP*)



CD Expert !






CD Lecture

Catalytic Packings: Aspects of Selection

CatalyticPacking

Reaction Rate(Catalyst Holdup: εcat)

Mass TransferEfficiency

(Number of TheoreticalStages: NTSM)

Hydraulic Capacity(Void Fraction: 1 - εcat)

Catalytic Bales (CD Tech)

see e.g. Smith, L. A. et al., EP 466954 A1 (1990)

Catalyst Beads

Fiber Glass Cloth Wire

Feed

Bottoms

Distillate

Catalytic Distillation Trays

D

RR

DD

D

Domenico, S. et al., US 5493059 (1996)

SNAMPROGETTI

Lionel, A. et al., US 5368691 (1994)

IFP

RD

R

R

D

D

Jones Jr., Edward M., US 5130102 (1992)

CR & L

R R

D

D

R R

D

D

Three-Levels-of-Porosity Concept

see e.g.: Krishna, R., Sie, S.T., Chem. Eng. Sci 49 (1994) 4029-4065.

I. µ-Pores inside catalytic particlesII. mm-Pores between catalytic particlesIII. cm-Pores between the catalytic pockets

Three Pore Levels:

Separation zone

Reaction zone

Structured Catalytic Packings

KATAPAK-S (Sulzer Chemtech)

Stringaro, J.P., EP 631813 A1 (1993)

MULTIPAK (Julius Montz)

Gorak, A., Kreul., L. U., DE 197 01 045 A1 (1998)

Hydrodynamic Behaviour of StructuredCatalytic Packing

§ Gas flow through open channels (1)

§ Liquid flow through open channels and catalyst bags (2)

§ Liquid holdup in open channels increases resistance for gas flow

§ Load point determines max. liquid flow through catalyst bags

Adopted from: Hoffmann, A., Gorak, A. (2000)Treffen der GVC-Fachausschüsse in Wernigerode.

Internally Finned Monoliths (IFM)

Lebens, P. J. M., Kapteijn, F., Sie, T.N., Moulijn, J.A., Chem. Eng. Sci. 54 (1997) 1359-1365.

ε

S/V

MacroporousSupport

(Pores: 3 µm)

Catalytic Distillation Process for Fuel Ether Production (TU Clausthal)

Catalytically ActiveRings (8x8 mm)

Feed

Gel Particles (1-2 µm) with R-SO3

-H+ as Acidic Functional Groups, cL = 1,0 eq(H+)/l

Supported IonExchange Resin

InertPacking

see e.g.: Hoffmann, U. et al., DP 4234779.3 (1992); Sundmacher, K. and Hoffmann, U. (1996) Chem. Eng. Sci. 51, 2359-2368.

CatalyticPacking

Gel Particles in Catalytic Rings (TU Clausthal)

see e.g.: Sundmacher, K.; Künne, H.; Kunz, U. (1998) Chem.-Ing.-Tech. 70, 267-271.

10 µm

PorousGlass

Support

GelParticle

Some Properties of Catalytic Packings

0.49

0.51

1129

576

Void Fraction

Catalyst Loading

Catalyst Surface-to-Volume Ratio

PackingSurface-to-Volume Ratio

0.75*

0.20*

4000*

800*

0.75*

0.20*

4000*

800*

0.75*

0.25*

4000*

1000*

[m3/mcol3]

[mcat3/mcol

3]

[mcat2/mcat

3]

[mcat2/mcol

3]

* See: Lebens, P. J. M., Kapteijn, F., Sie, T.N., Moulijn, J.A., Chem. Eng. Sci. 54 (1997) 1359-1365.



CD Expert !






CD Lecture

Modelling, Simulation and Experimental Validation:Etherification Reaction Systems

Heterogeneous Catalysts: Macroporous Sulfonic Acid Ion Exchange Resins

Reactive Olefins: IA = Isoamylenes (2M1B + 2M2B)

Inert Solvent: n-Pentane (nP)

Reactive Olefin: IB = IsobuteneSide Product: DIB = DiisobutenesInert Solvent: 1-Butene (1B)

TAME-System: Reaction Triangle

CH2=C(CH3)-CH2-CH32-methyl-1-butene (2M1B)

CH3-C(CH3)=CH-CH32-methyl-2-butene (2M2B)

CH3-CH2-C(CH3)2-O-CH3(TAME)

+ Methanol(MeOH)

+ Methanol(MeOH)

rISO

rTAME1

rTAME2

MTBE-System: Parallel Reactions

C(CH3)3-O-CH3(MTBE)

rMTBE

C8H16Diisobutene (DIB)

rDIB

+ (CH3)2C=CH2Isobutene (IB)

+ Methanol(MeOH)

(CH3)2C=CH2Isobutene (IB)

Sorption Behaviour at Catalytically Active Gel Phase of Acidic Ion Exchange Resin

* see e.g.: Jaroniec, M., Patrykiejew, A., Borowko, M., Prog. Surf. Mem. Sci. 14 (1981) 1-68.

Liqu

id P

hase

Act

ivity

, ai

Method: UNIQUACTemperature: 60 °C

Mole Fraction Methanol, xi

010

1

Methanol

Isobutene

Nonideal Mixing Behaviour ofMeOH/IB in the Liquid Phase

Generalized Langmuir SorptionIsotherm*:

θ iS i i

S j j

K a

K a=

∑,

,

1+ j=1

N

LiquidPhase

θiai

KS,i

Gel Phase

Microkinetics of Liquid Phase Etherificationat Acid Ion Exchange Resins

For MTBE-kinetics see: Rehfinger, A., Hoffmann, U. (1990) Chem. Eng. Sci. 45, 1605-1617For TAME-kinetics see: Oost, C., Hoffmann, U. (1996) Chem. Eng. Sci. 51, 329-340

- reaction of sorbed species israte retermining step

- methanol sorption in thecatalytic gel phase is highly selective: KS,MeOH » KS,i

( ) ( )

−= −

21

MeOH

Ether

aMeOH

OlefinIso

aa

TKaa

Tkr

l Experimental Data from CSTR

Liquid Phase ReactionT = 60 °CCat.: A 15 / SPC 118dp = 42 µm / 200-315 µm

Mole Fraction Methanol, xMeOH

MTB

E F

orm

atio

n R

ate,

rx (c

IO/c

O)-1

/ [m

mol

/(s·e

q)]

l General Rate Expression for Etherification of iso-Olefins

( )kJ/mol 4.92

eq)mmol/(s 5.1560

, =⋅=°=

MTBEa

MTBE

ECTk

.

( )kJ/mol 5.89

eq)mmol/(s 58.260

, =⋅=°=

TAMEa

TAME

ECTk

MTBE

TAME

MTBE

TAME

V LS

Vjxi,j

V

hjV

TjV

Lj-1xi,j-1

L

hj-1L

Tj-1L

Vj+1xi,j+1

V

hj+1V

Tj+1V

Ljxi,j

L

hjL

TjL

QjU

Qreb

Fm

α,β

R

j - 1j

j + 1

p

Modeling of Catalytic Distillation Column

PSEUDOHOMOGENEOUS MODEL+ V/L mass transfer model + reaction microkinetics

HETEROGENEOUS MODEL(„Fully rate-based“)+ V/L mass transfer model+ reaction microkinetics+ intraparticle mass transfer

(Maxwell-Stefan-eqs.)

SPECIFICATIONS+ specifications: p, F, α, β, Q, R

Packed Catalytic Distillation Column:Control and Measuring Devices

Operating Parameters:

l Operating pressure, p

l Reflux ratio, r

l Heating rate, Qreb

l Feed mass flow rate, Fm

l Molar feed composition:

α = Methanol/iso-Olefins

β = iso-Olefins/Hydrocarb.

1el.

el.

1

M

TIR

TIR

TIR

FIR

LIRC

TIRC

2 PIRC

TIRC

6-10

11

PDIR

1-5

1FIR

2

1.1

1.3

TIC12-13

2LIRC

M

W I I

W I I1

3el.

W I I2

CoolingWater

Distillate

Feed (Fm, α, β)

Bottom Product

Reboiler(Qreb )

Packingof Catalytic Rings

Packingof Inert Rings

Catalytic Distillation Column for TAME-Production(Pseudohomogeneous Model)

p = 0.5 MPar = 4Qreb = 520 WFm = 1.1 kg/hα = MeOH/IA = 1.0β = IA/(IA + nP) = 0.3

ExperimentSimulation

Axi

al C

olum

n C

oord

inat

e, z

[m]

Liquid Phase Temperature, TL / [°C]80 90 100 110 120 1300

0.2

0.4

0.6

0.8

1

1.2

1.

1.

4

6

Sundmacher, K.; Gravekarstens, M.; Rapmund, P.; Thiel, C.; Hoffmann, U.: AIDIC Conf. Series 2 (1997) 215-221.

Exp. DataSimulation

0 0.2 0.4 0.6 0.8 1Liq. Mole Fraction of C5, xL

C5

0

0.2

0.4

0.6

0.8

1

Liq.

Mol

e Fr

actio

n of

MeO

H, x

L MeO

H

Az2

Az1Az1

Experiment Experiment

TT

MM

BBRebReb

SimulationSimulation

FmxF

MeOH / xFIAxF

MeOH / xFIA

xFIA/ xF

C5xFIA/ xF

C5pprrQRebQReb

= 1,1 kg/h= 1,0= 1,0= 0,3= 0,3= 0,5 MPa= 4= 4= 520 W= 520 WEqui. Nonequi.Equi. Nonequi.

G/L/SG/L/S

G/LG/L

TAME

MeOH



CD Expert !






CD Lecture

Influence of Reflux Ratio on Conversion

Bessling, B.; Löning, J.M.; Ohligschläger, A.; Schembecker, G.; Sundmacher, K., Chem Eng. Technol. 21 (5), 393-400.

Conversion of Acetic Acid

Methyl Acetate

Acetic Acid

Water

Catalytic Section (ICVT-Rings)

Rectifying Section (Rombopak 9M)

Stripping Section (Rombopak 9M)

Methanol

Methyl Acetate

Acetic Acid

Water

Catalytic Section (ICVT-Rings)

Rectifying Section (Rombopak 9M)

Stripping Section (Rombopak 9M)

Methanol

There is an optimal reflux ratio !

Bifurcation Analysis of Catalytic Distillation Columns

Mohl, K.-D.; Kienle, A.; Gilles, E.-D.; Rapmund, P.; Sundmacher, K.; Hoffmann, U., Chem. Eng. Sci. 54 (1999) 1029-1043.

MTBE processp = 11 bar

TAME processp = 2 bar

Modell equilibrium stage approachl overall efficiency E = 0.8 or 0.7l MTBE: UNIQUAC; TAME: Wilsonl heat losses along columnl rate expression: r = r(T, a)

Ref

lux

Rat

io, R

/ [ -

]x E

ther

B/ [

-]

3 steadystates

Heating Rate, Qreb / [kW] Heating Rate, Qreb / [kW]

R = L / D

RD Zone(5 Stages)

Stripping Zone(5 Stages)

MeOH +Olefins

Qreb

30.00.1

==

βα

3 steadystates

Multiple Steady States of TAME CD Column:Model Predictions and Experimental Results

Mohl, K.-D.; Kienle, A.; Gilles, E.-D.; Rapmund, P.; Sundmacher, K.; Hoffmann, U., Chem. Eng. Sci. 54 (1999) 1029-1043.

Experimental Liquid Phase TemperaturesModel Predictions

Col

umn

heig

ht, z

/ [m

]x T

AM

EB

/ [ -

]

Col

umn

heig

ht, z

/ [m

]

Temperature, T / [°C]

Heating Rate, Qreb / [kW]

Temperature, T / [K]

TIR10

TIR 5

Oscillatory Behaviour of MTBE RD Columns

Predictions based on RD model implementedin SPEEDUP(Schrans et al., 1996)

Experimental result from lab scale column(Sundmacher and Hoffmann, 1995)

ý tray / packing hydraulics can lead to conjugate complex eigenvalues of system matrix resulting in oscillatory behaviour by Hopf bifurcations.

B

R = 7

Rectification Zone (2 Stages)

RD Zone(8 Stages)

Stripping Zone (5 Stages)

MeOH + C4

p = 11 bar

α = 1.1β = 0.36

R = 4...7

RD Zone(GPP, 0.5 m)

Stripping Zone(0.5 m)

MeOH

C4

p ≈ 6.5 bar

Qreb= 560 Wα = 1.0β = 0.3 Time, t / [s]

Ref

lux,

L / [

ml/m

in]

Con

vers

ion

IB, X

IB/ [

-]

Time, t / [h]

Catalytic Distillation (CD)

4 Modelling, Simulation,Expérimental´Validation

CD Expert !





CD Lecture


Many thanks for fruitful scientific co-operation with

§ Prof.-Ing. Achim Kienle, Dipl.-Ing. Erik Stein,

Dr. Zhiwen Qi, Dr. Aspi Kolah (all MPI-Magdeburg)

§ Dipl.-Ing. Klaus-Dieter Mohl (Stuttgart University)

§ Dr.-Ing. Ulrich Kunz, Prof. Dr.-Ing. Ulrich Hoffmann (TU Clausthal)

Many thanks to the FHI organisers for invitation!

Acknowledgements


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