Table 1 Literature EtAc experimental setups and corresponding purity levels

Case

Process Configurati

EtOH

EtOH

Overhead Product

H2SO

EtOH

NT=82 RD Column

EtOH

Overhead Product

NT=82 RD Column

Bottom Product

EtOH.

Aqueous roduct

Overhead Product

Bottom Product

Aqueous roduct

EtOH.

Overhead Product

Bottom Product

HAc EtOH_ Water

Overhead Product

NT=13

EtOH.

Bottom Product

EtOH.

Product

Bottom Product

Authors

Kenig et al., 2001

Reepmeyer et al., 2004

Kolena et al., 2004 (US Patent#6693213)

Process

A fixed bed reactor w/ a RD column

Homogeneous catalyst, 80 bubble cap trays

A RD column w/ decanter, organic partial reflux

Single Column

A RD column w/ decanter, organic partial reflux c Approach

Experiment

Simulation and Experiment

Simulation and Experiment

Simulation and experiment

Experiment

Conversion

Purity

Xeiac= 96.36wt%

XEtAc~60mol%

Xeiag- 40wt%

others

Coupled structure (pre-reaction)

Two different column diameters with two different internals were used

Focus on time-optimal start-up strategies

10 11 12

20 21 22

Table 2 Temperatures and compositions of azeotropes for EtAc system (1 atm).

C

Experimental*

Exp.*

Components

Temp.( oC)

EtOH/EtAc

(0.462, 0.538)

71.81

EtOH/H2O

(0.9037, 0.0963)

78.174

EtAc/H2O**

(0.6885, 0.3115)

70.38

EtOH/EtAc/H2O

(0.1126, 0.5789, 0.3085)

70.23

Table 3 Summary of 6 experimental Start-up runs with feed condition, initial holdup composition, operating condition, and product purity.

Run #

1

2

3

4

5

6

Date

2006-02-24

2006-05-12

2006-05-22

2006-05-29 *

2006-06-12

2006-06-23

Feed Condition

Xacid (mf)

0.9675

0.9675

0.9675

0.9675

0.9675

0.9675

XEtOH (mf)

0.8698

0.8698

0.8698

0.8698

0.8698

0.8698

Facid (mol/min)

0.3641

0.1821

0.1821

0.2858

0.2858

0.2858

FEtOH(mol/min)

0.4008

0.1961

0.1954

0.3067

0.3067

0.3067

Molar ratio(Acid/EtOH)

0.960

0.985

0.985

0.985

0.985

0.985

WHSV

1.302

0.644

0.644

1.01

1.01

1.01

Initial Holdup Composition

RD Base (VAcid/VHOa)

5/1

4/1

¥ (pure acid)

15/1

¥ (pure acid)

¥ (pure acid)

Decanter (VEtAc/Vwater)

2/1

4/1

¥ (pure EtAc)

¥ (pure EtAc)

¥ (pure EtAc)

¥ (pure EtAc)

Stripper bottoms

N/A

(pure EtAc)

(pure EtAc)

(pure EtAc)

(pure EtAc)

(pure EtAc)

Operation condition

Organic Reflux (mol/min)

1.4360

1.2721

1.5839

1.0617

1.0862

1.6289

Feed to Stripper(mol/min)

1.4360

0.7587

0.9123

0.6066

1.5207

1.5203

Reflux Ratio

1

1.68

1.73

1.75

0.71

1.07

Hot oil flow rate (L/min)

RD column

2.8

2.1

3

2

2

3

Stripper

2

1.5

0.3

0.2

2

2

Acetic Acid Conversion(%)

~100

~100

~100

~100

~100

~100

XB,EtAc (mf)

0.4056

0.9723

0.9225

0.9132

0.996

0.9995

10 11 12

20 21 22

Table 4 Kinetic Equations for EtAc System.

system

Kinetic model (Catalyst)

(T = 363K)

(T = 363K)

EtAc

Pseudo-homogeneous model (Amberlyst 35 wet)

r _ mcat (k1CHAcCEtOH ~ k-1CEtAcCH2O )

k = 1.24 xl09 exp(-6105'6) k1 = 1.34 x 108 exp(_5692 1)

66.47 (cm6 mol-1 g-1 min-1)

2.96

T [K], r [mol/min], mcat [gcat], Ci [mole concentration].

10 11 12

20 21 22

Fill

Table 5 Settings in Aspen Plus simulation.

Table 5 Settings in Aspen Plus simulation.

Simulation

EtAc

Column configuration

RD column

Stripper

VLE model Catalyst Kinetics model

Tang et al.[l] Amerlyst 35 wet Table 6

Tang et al. [1]

No. of trays in the stripper (Ns)

-

10

No. of trays in reactive section (Nrm)

11

No. of trays in rectifying section (Nr)

10

-

Reactive tray

0-10

{

Acetic acid feed tray

0 (column base)

Alcohol feed tray

0 (column base)

Tray efficiency

rectifying section ( r\,.)

0.9

-

Stripper trays ( r\ s)

-

0.9

Feeds

Xacid (mf)

0.9675

XEt0H (mf)

0.8698

Facid (mol/min)

0.2858

FEtoH(mol/min)

0.3067

Molar ratio(Acid/EtOH)

0.985

Operating variables

Reflux Ratio

1.07

Reboiler duty (kW)

1.508

1

Column diameter (m)

0.05

0.05

Decanter temperature (°C)

20

Catalyst weight (g)

Reactive Tray

88

-

RD Bottom

880

-

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