k - AIChE

Transcription

k - AIChE

The Dynamic Behaviour of Industrial Plants
for the Production of PLA by ROP of Lactides
F. Codari, L. I. Costa, P. Kreis, U. Trommsdorff
Sulzer Chemtech
AIChE Annual Meeting, 2013
Outline
Sulzer Chemtech
Introduction
(Poly)lactic acid
Sulzer PLA process
Process scale-up
Mathematical models
Model validation and parameter estimation
Model predictions: steady state and dynamic conditions
Use of the model to compare the performances of different reactors
CSTR versus loop
Loop + PFR versus PFR
Conclusions
AIChE Annual Meeting | Nov 2013 | slide 2
World Bioplastics Production
Sulzer Chemtech
PLA
Biodegradable
100% biobased
Bio-PET
30% biobased
Polylactic acid (PLA)
Most produced bio-based polymer not meant as drop-in bioplastic
Applications
Thermoformed items and films for packaging
Injection molded goods and 3D-printed objects
Fibers and foams
IfBB 2013: http://ifbb.wp.hs-hannover.de/downloads/
Sulzer Building Blocks
Sulzer Chemtech
Static mixers SMX™ / SMX™plus /
SMXL™
Heat exchanger/reactor SMR™
Devolatilization technology
Static equipment
Narrow / low residence time
High interphase area for optimal
control of temperature
PLA Process
Sulzer Chemtech
monomer
monomer
monomer
+
cat
PLA
PLA
Continuous
mixing reactor
All units are made of static mixers or
SMRs™
Plug Flow
Reactor
2 Stage
Devolatilization
High reaction rate and low residence
time
Minimization of
No segregation
No hot spots
Racemization
Optimal control of temperature profile
Chain scission (MW decrease)
Side reactions (yellowness)
PLA Process: Proven Technology
Sulzer Chemtech
Foto Supla
5 kta, Synbra (NL), 2010
2007
2010
Sulzer 0.2 kta pilot plant, 2007
10 kta, Supla (Asia), 2014
2013
Sulzer 1 kta Demo plant, 2013
2016
2019
Scale-up to > 50 kta
PLA Process: Proven Technology
Sulzer Chemtech
Demonstration plant 1 kta in Pfäffikon (CH)
Standard grade portfolio available for market development and application testing
Access to PDLA grades
http://www.sulzer.com/en/Products-and-Services/ProcessTechnology/Polymer-Production-Technology/PLA-SamplesOrder-Form
Outline
Sulzer Chemtech
Introduction
(Poly)lactic acid
Sulzer PLA process
Process scale-up
Mathematical models
CSTR versus loop
Conclusions
PLA Process: Scale-up
Sulzer Chemtech
Model Prediction
Parameter Fitting and Model Validation
5 kta, Synbra (NL), 2010
Mn [kg/mol]
300
200
100
0
0
5
10
monomer
monomer
10 kta, Supla (Asia), 2014
monomer
monomer
+
cat
PLA
monomer
monomer
+
cat
PLA
batch
experiments
50kta, 75kta, 100kta…
pilot plant for
development tests
(0.2 kta)
in FEED Stage
demonstration plant
(1 kta)
production plant
Model: Kinetic Scheme
ka 1
C + Dn Pn + A
ka 2
kp
Pn + M Pn + 2
Sulzer Chemtech
Catalyst activation
Parameter
Reversible propagation
K eq =
kd
ks
ka1
ka 2
Value
batch
ka1
>> 1
ktr
kp
literature
ktr
kd
literature
ks
>> 1
ktr
pilot plant
kde
pilot plant
Pn + Di Dn + Pi
Reversible chain transfer
ks
Pi + Pj Pi + j − n + Pn
ktr
Pi + D j Pi + j − n + Dn
ktr
ktr
Intermolecular
transesterification
Pi + G j Pi + j − n + Gn
ktr
k de
Pi → Pi − k + Gk
kde
Di → Di − k + Gk
k de
Gk → Gk − j + G j
Non-radical random
chain scission
Literature
Yu et al., I&ECRes, 2011
Kowalski et al, Macromolecules, 2000
Witzke et al., Macromolecules, 1997
Kinetic Model: PBEs and Mass Balances
Sulzer Chemtech
Each mixer / SMR™ is modeled as a PFR
Method of moments is applied
∂[C ]
=
∂t
∂[ M ]
=
∂t
∂λ0
=
∂t
∂λ1
=
∂t
∂[C ]
∂x
∂[ M ]
−v
∂x
∂λ
−v 0
∂x
∂λ
−v 1
∂x
−v
− ka1[C ]µ0 + ka 2 [ A]λ0
− k p [ M ]λ0 + kd λ0
+ ka1[C ]µ0 − ka 2 [ A]λ0
+ ka1µ1 [C ] − ka 2 λ1 [ A] + 2k p λ0 [ M ] − 2kd λ0 − ks λ1µ0
1
+ ks λ0 µ1 − ktr λ1 ( µ1 − µ0 ) + ktr λ0 ( µ 2 − µ1 )
2
1
1
− ktr λ1 ( γ 1 − γ 0 ) + ktr λ0 ( γ 2 − γ 1 ) − kde ( λ2 − λ1 )
2
2
∂λ2
=
∂t
−v
∂λ2
∂x
....
Viscosity Model and Model Implementation
Sulzer Chemtech
∂P
= − KvF (η )
∂x
sinh −1 (η 0 γB)
η=
γB
 MW
η 0 = η 0,ref X n 
 MWref
T
a


 exp E att

 R


1
 − 1
T T
ref





Model implemented in gProms
Process modeling platform
Batch Reactor
Sulzer Chemtech
Determination of catalyst activation as a function of free acid impurities:
 X eq 
Y = ln 
 = k p [ λ0 ] t
−
X
X
 eq

Parameter
K eq =
free acid
ka1
Value
batch
ka 2
ka1
>> 1
kp
literature
kd
literature
ks
>> 1
ktr
pilot plant
kde
pilot plant
Similarly, the effect of other relevant process parameters can be studied
Temperature
Catalyst / ROH
Pilot Plant 0.2 kta
Steady state results
Sulzer Chemtech
200
150
kde = α kderef
150
100
Mn [kg/mol]
Mn [kg/mol]
● Exp data
▬ Model
ROH
50
0
0
0.5
X
1
100
50
0
0
Xeq = 0.95-0.97[1]
α
α
α
α
α
0
0.2
0.5
1
0.5
X
1
Full conversion up to equilibrium conditions
Mn vs. X behavior living polymerization + reversible chain transfer reaction
Polymerization proceeds to full conversion with negligible polymer degradation
Rate parameter for chain scission, kde, set to zero for all simulations
[1] Witzke et al., Macromolecules, 1997
[2] kderef from Yu et al., I&ECRes, 2011
Pilot Plant 0.2 kta
Steady state results
Sulzer Chemtech
Evaluation of transesterification rate coefficient (ktr)
Mainly affecting the evolution of Mw
Parameter
300
● exp data
▬ model
Mw [kg/mol]
ROH
K eq =
200
100
0
0
5
Length
10
ka1
ka 2
Value
batch
ka1
>> 1
kp
literature
kd
literature
ks
>> 1
ktr
pilot plant
kde
pilot plant
Demonstration Plant 1 kta
Steady state predictions
Sulzer Chemtech
Good agreement between model prediction and experimental data collected
under different reaction conditions on the 1 kta demonstration plant
Reliable model suitable for plant scale-up
Pilot Plant 0.2 kta
Dynamic behavior predictions
Sulzer Chemtech
Change feed conditions
Fully predictive simulations
300
● Exp data
▬ Model
200
monomer
+
cat
Cat/ROH concentration change
300
150
100
50
Cat/ROH concentration change
250
time [h]
Good prediction of molecular weight
dynamic behavior
Mw [kg/mol]
Mn [kg/mol]
250
200
150
100
50
● Exp data
▬ Model
time [h]
Pilot Plant 0.2 kta
Dynamic behavior predictions
Sulzer Chemtech
100
P [bar]
80
60
Model
Exp
Model
Exp
Cat/ROH change
P
40
monomer
+
cat
20
048
48
49
49
50
51
50
51
time [h]
52
52
P
53
53
Satisfactory prediction of pressure dynamic behavior
Assumption of ideal PFR behavior for each unit is confirmed
Outline
Sulzer Chemtech
Introduction
(Poly)lactic acid
Sulzer PLA process
Process scale-up
Mathematical models
CSTR versus loop
Conclusions
Comparison of Reactors
Loop versus CSTR
Sulzer Chemtech
0.8
Conversion
Similar dynamic behavior at high
recirculation ratios[1]
0.6
0.4
r=1
r = 2.5
r = 6.5
CSTR
2000
4000
6000
time [s]
0.2
0
0
1000
Interphase area and heat exchange
V ∆T
[ KW / m³ °C]
Loop made of SMR versus CSTR
.
Q
100
Sta
tic
10
Em
pty
1.0
tub
e
mi
xe
r
Ext
SMR
rud
er
0.1
CS
T
0.0
0.1
1.0
10
102
Values given apply for high viscous liquids
[1] Zacca and Ray, Chem. Eng. Sci. 48, 1993
103
R
104
105
106
Volume [litres]
Loop versus CSTR
volume
=
=
area
>
<
overall heat
transfer coeff
=
=
Sulzer Chemtech
polymer/monomer solidification
Loop: Difference between process and oil temperature < 10°C even for large
reaction volume
Lower risk of “wall effect” in loop Limited temperature gradient
CSTR non-operable in one stage above 100 l reactor volume
Sulzer Chemtech
Perturbation: i) catalyst stop and restart conversion
A%
A%
Sulzer Chemtech
Perturbation: i) catalyst stop and restart MW and viscosity
A%
A%
Conclusions
Sulzer Chemtech
Sulzer PLA process is characterized by
Full conversion and efficient devolatilization to low RM values
No polymer degradation (MW loss)
Minimal polymer discoloration due to minimization of side reactions: YI << 10
Low racemization < 0.3%, giving access to high purity PLLA and PDLA grades
Sulzer PLA process is scalable from batch to large industrial plants
Modeling of Sulzer PLA process shows
Good agreement between experimental results and mathematical model
Improved temperature control as compared to CSTR (due to high heat exchange area)
Minimized perturbation effects as compared to pure PFR process (due to loop + PFR
configuration)
Sulzer Chemtech
Thank you for your attention!

k - AIChE

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