APM Forum 2019

Advanced process modelling of TAME industrial synthesis in gPROMS®

Elena Catalina Udreaa, Stefan Toadera, Valentin Plesua*, Alexandra-Elena Bonet-Ruiza,b, Petrica Iancua, Jordi Bonetb a University POLITEHNICA of Bucharest, Centre for Technology Transfer in Process Industries, CTTIP. Bucharest, Romania

b University of Barcelona, Department of Chemical Engineering and Analytic Chemistry, Barcelona, Spain

*corresponding author: v_plesu@chim.upb.ro

Introduction TAME synthesis process is widely used as gasoline additive. This study develops a mathematical model in gPROMS®

ModelBuilder simulating the behavior of two fixed bed catalytic reactors for TAME synthesis in an industrial plant.

Additionally, the plant includes TAME distillation column, methanol recovery section and auxiliary devices. Model

implementation is supported by calculations made with SIMULIS®. As starting points for modelling, data from TAME

synthesis process in industrial plant are used. Each reactor consists in a fixed bed of acidic catalyst (Amberlyst 35 wet)

of 7.6 m height and 2 m diameter. The two dimensions (axial and radial) model, ER type, is used to obtain appropriate

molar concentration, temperature and reactions rates profiles in time. For numerical integration, BFDM (backward finite

difference method), proved to be stable in axial direction, and OCFEM (orthogonal collocation on finite elements method)

is used in radial direction. Comparison with industrial data shows reasonable agreement.

RESULTS

Numerical stability evaluation on axial integration with CFDM

(centered finite difference method) and BFDM (backward finite

difference method) on temperature profile

TAME reaction system

Mathematical Model

Component Mass Balance

Energy Balance

The kinetic model (proposed by Ferreira and Loureiro,

2004[1]), follows the Eley-Rideal mechanism [2,3].

References I). M.V. Ferreira, J.M. Loureiro, Number of actives sites in TAME synthesis: mechanism and kinetic modeling, Ind. Eng. Chem. Res. 43 (2004) 5156–5165.

2). Oost, C.; Hoffmann, U. The Synthesis of Tertiary Amyl Methyl Ether (TAME): Microkinetics of the Reactions. Chem. Eng. Sci. 1995, 51, 329.

3). W.Mao, X. Wang, H.Wang, H. Chang, X. Zhang, J. Han. Thermodynamic and kinetic study of tert-amyl methyl ether (TAME) synthesis. Chem. Eng. and Proc. 47 (2008) 761-769

4). Muja, I., Nastasi, A., Obogeanu, F., Grozeanu, I., Anghel, C. (1994). Synthesis process for metoxylated gasoline (Rom.). State Office for Inventions and Trademarks, Bucharest,

Romania, 108972 B1.

Acknowledgments The financial support of the European Commission through the European Regional Development

Fund and of the Romanian state budget, under the grant agreement 155/25.11.2016 (Project POC

P-37-449, acronym ASPiRE) is gratefully acknowledged.

Reaction system

gPROMS® Project structure

Industrial TAME process [3]

Methanol recovery section

0 ≤ z ≤ L, 0 ≤ r ≤ R, t ≥ 0,

Where:

2 2

2 2

1v λ λ

, 0, , 0

1

,

f pf f pf ss z ro

b j j

j RE

lid s

AC

p

T T T T TC C

t z z r r r

r H z L r

C

R

Defining composite MODELs

2

,1 2 1

12

1 21

TAMEap MeOH M B MeOH

eq

MeOH MeOH

ak K a a

Kr L

K a

2

,2 2 2

22

3 21

TAMEap MeOH M B MeOH

eq

MeOH MeOH

ak K a a

Kr L

K a

2 2,3 2 1

3

51

M Bap MeOH M B

eq

MeOH MeOH

ak K a

Kr L

K a

a) CFDM b) BFDM

Kinetic model for TAME synthesis

Industrial reactor series

(z)

R1 reactor

R2 reactor

F, xi

Reactor physical model

Sub-models

Activity coefficient

Physical properties

Transport properties

List of the variables

used in the model

Instantiation of the model

2 2

,2 2

1  v ,

  z 0,L , r 0,R ,  i COMP , COMP 2M2B,  MeOH,  TAME,  2M1B,  iC5

i i i i is z r b i j j

j REAC

C C C C CD D r

t z z r r r

R1 reactor F, xi R2 reactor

R1 reactor

T, Ci i

Physical properties

T

Transport properties

Activity coefficient

L D

• Physical properties can be obtained

from an external data base or

calculated for each point as a sub-

model.

• SIMULIS® provides information and

equations for the physical properties

calculation of the reactor.

First reaction rate in the second reactor

on the two dimensions at 1.4 hour Conclusions gPROMS® is a suitable environment for advanced process modelling. Detailed mathematical model is proposed for component mass balance and energy

balance supported by adequate thermodynamic and kinetic models for reactors. Model solution with BFDM proved to be stable. Time and space profiles for

temperature and reaction rate are presented in a high quality graphics. Time profiles show that the steady state conditions are reached quite quick. The model

developed in this study proved to describe well the industrial scale reactors. Model solution results give detailed information about the behavior of both reactors.

These results can assist the process engineer in decision making on correct process operation.

First reaction rate in the first reactor

on the two dimensions at 1.2 hour

Components Industrial

data

gPROMS®

results

Effluent

R2

TAME 0.1873 0.209

IA 0.0632 0.099

Methanol 0.0384 0.035

Inert 0.6985 0.657

IA = isoamylenes

Inert = isopentane