This document outlines the steps to design a separation process for a mixture of methyl acetate, methanol, acetic acid, and water. The steps include: 1) Analyzing the mixture components and their properties 2) Creating a binary ratio matrix to identify feasible separation techniques 3) Selecting distillation as the first separation based on ease of separation 4) Generating a process flowsheet using distillation columns 5) Verifying the flowsheet design using process simulation software.

1. SAJJAD KHUDHUR ABBAS
Ceo , Founder & Head of SHacademy
Chemical Engineering , Al-Muthanna University, Iraq
Oil & Gas Safety and Health Professional – OSHACADEMY
Trainer of Trainers (TOT) - Canadian Center of Human
Development
Episode 57 : Simulation
for Design and Analysis

2. Problem Description
Methyl-acetate is produced by esterification of methanol and acetic acid which
produces water as by-product.
CH3OH + CH3COOH CH3COOCH3 + H2O
The mixture to be separated is an outlet stream from a reactor (assumed conditions:
P=1 atm, T=450 K) and the methyl-acetate product specification is 99 %.
Problem statement: Given the identity and composition of the components in the
mixture to be separated, together with the product specifications, identify a physically
feasible flowsheet for separation of the mixture into the specified products. Determine
the estimates of operating conditions and identify a MSA where required. Verify the
generated process flowsheet with process simulation, together with the alternative
separation techniques for its separation task.

3. Tasks to perform ?
1. Analyze mixture
2. Compute binary ratio matrix
3. Identify separation techniques
4. Screen alternatives
5. Compute separation factor
6. Select the first separation task
7. Generate process flowsheet
8. Analyze decisions
9. Verify flowsheet

4. Tasks to perform ?
1. Analyze mixture
Nature of mixture
State of components at a reference condition
Number of binary pairs
Analysis of azeotropes
Liquid miscibility, solubility & solvents

5. Tasks to perform ?
1. Analyze mixture
State of components at reference conditions (T = 298 K, P = 1 atm): All components
are liquids at reference conditions, since their boiling points are: MeAc (330.1 K),
MeOH (337.7 K), H2O (373.2 K), HOAc (391.0 K).
Number of binary pairs: There are 6 binary pairs (MeAc/MeOH, MeAc/H2O,
MeAc/HOAc, MeOH/H2O, MeOH/HOAc, and HOAc/H2O).
Identification of azeotropes with pressure dependence: The following pairs form
azeotropes at P = 1 atm, based on vle data (see table below).
Table I: Azeotropes at P = 1 atm for methyl-acetate example
Binary pair Azeotrope T (K) , x (mole %)
MeAc/H2O 330.1 K , 92.8 % MeAc
MeAc/MeOH 328.1 K , 67.4 % MeAc
H2O/HOAc 371.8 K , 15.7 % HOAc

6. Tasks to perform ?
1. Analyze mixture
Table II: Mutual solubilities for methyl-acetate example
Table III: Solubility parameters in methyl-acetate example
Binary pair Mutual
solubilities
(gr/cm3
)
Binary pair Mutual
solubilities
(gr/cm3
)
MeAc in MeOH 0.652 MeOH in MeAc 0.131
MeAc in HOAc 1.146 HOAc in MeAc 0.385
MeAc in H2O 0.162 H2O in MeAc 0.027
MeOH in HOAc 0.342 HOAc in MeOH 1.947
MeOH in H2O 0.988 H2O in MeOH 0.280
HOAc in H2O 0.917 H2O in HOAc 0.124
Component Solubility parameter
(Mpa1/2
) (ProPred)
Solubility parameter
(Mpa1/2
) (databank)
MeAc 19.35 19.35
MeOH 27.46 29.6
HOAc 29.73 19
H2O 47.8 47.8

7. Tasks to perform ?
1. Analyze mixture
Table IV: Multi-phase flash calculation for MeAc/MeOH/CO2 system
Table V: Multi-phase flash calculation for MeAc/H2O/CO2 system
Feed stream
(kmol/hr) (molefractions)
T = 420 K , P = 75 atm
Phase 1 (molefractions) Phase 2 ( molefractions )
MeAc 67.4 0.337 0.176 0.484
MeOH 32.6 0.163 0.098 0.222
CO2 100 0.500 0.726 0.294
Fraction of feed 0.476 0.524
Feed stream
(kmol/hr) (molefractions)
T = 420 K , P = 75 atm
Phase 1 (molefractions) Phase 2 ( molefractions )
MeAc 92.8 0.464 0.232 0.639
H2O 7.2 0.036 0.024 0.045
CO2 100 0.500 0.744 0.316
Fraction of feed 0.430 0.570

8. Tasks to perform ?
2. Binary ratio matrix : rk = pk / pk
ij i j
where i and j are component indices and, pk
i > pk
j

9. Tasks to perform ?
2. Binary ratio matrix : rk = pk / pk
ij i j
where i and j are component indices and, pk
i > pk
j
Table VIII: Computed binary ratio matrix for methyl-acetate example
Ratio of properties for binary pairs
Property MeOH/
HOAc
MeOH/
MeAc
MeOH/
H2O
HOAc/
MeAc
HOAc/
H2O
MeAc/
H2O
Molecular weight 1.87 2.31 1.78 1.23 3.33 4.11
Critical temperature 1.15 1.01 1.26 1.17 1.09 1.28
Boiling point 1.16 1.02 1.10 1.18 1.05 1.13
Dipolemoment 1.02 1.01 1.09 1.04 1.06 1.10
Radius of gyration 1.68 1.93 2.52 1.15 4.24 4.87
Melting point 1.65 1.00 1.56 1.66 1.06 1.56
Triple point
temperature
1.65 1.00 1.56 1.66 1.06 1.56
Triple point pressure 11455.3 9.12 5487.96 1255.5 2.09 601.5
Molar volume 1.42 1.97 2.25 1.39 3.19 4.42
Solubility parameter 1.56 1.53 1.62 1.02 2.52 2.47
Van der Waals
volume
1.53 1.96 1.76 1.28 2.69 3.44
Vapour pressure 8.11 1.70 5.32 13.78 1.52 9.04
Binary azeotrope at
P = 1 atm
No Yes No No Yes Yes

10. Tasks to perform ?
3. Identify separation techniques
4. Screen alternatives
Compare values of binary ratio matrix against
a similar matrix where the columns are
separation techniques. If the binary ratio
value is within the specified range for the same
property in the separation matrix, the select
the corresponding binary pair as the
separation task and the separation technique
as an alternative unit operation

11. 3. Identify separation techniques & 4. Screen alternatives
Table IX: Identified feasible separation techniques for methyl-acetate example
Task Separation technique
MeOH/HOAc Distillation, liquid membranes, stripping, pervaporation,
adsorption, absorption, crystallisation, cryogenic
distillation, desublimation, gas separation membranes,
sublimation, ultrafiltration
MeOH/MeAc Liquid membranes, pervaporation, adsorption,
distillation, extractive distillation, absorption, stripping,
azeotropic distillation, supercritical extraction (with CO2),
pressure swing distillation, pressure distillation, liquid
liquid extraction, microfiltration, ultrafiltration
MeOH/H2O Distillation, liquid membranes, pervaporation, adsorption,
stripping, absorption, crystallisation, extractive
distillation, cryogenic distillation, desublimation, gas
separation membranes, sublimation, ultrafiltration
HOAc/MeAc Distillation, crystallisation, liquid membranes,
pervaporation, adsorption, stripping, cryogenic distillation,
desublimation, gas separation membranes, sublimation
HOAc/H2O Liquid membranes, pervaporation, adsorption,
absorption, distillation, extractive distillation, stripping,
azeotropic distillation, supercritical extraction, pressure
swing distillation, liquid liquid extraction, microfiltration,
ultrafiltration
MeAc/H2O Distillation, liquid membranes, pervaporation, adsorption,
absorption, crystallisation, stripping, liquid-liquid
extraction, distillation+decanter, pressure swing
distillation, pressure distillation/P=0.3 atm, cryogenic
distillation, desublimation, gas separation membranes,
microfiltration, sublimation, ultrafiltration

12. Tasks to perform ?
1. Analyze mixture
2. Compute binary ratio matrix
3. Identify separation techniques
4. Screen alternatives
5. Compute separation factor
6. Select the first separation task
7. Generate process flowsheet
8. Analyze decisions
9. Verify flowsheet
split factors
easiest separation
first ?
repeat steps 6,
7 & 8

13. Tasks to perform ?
1. Analyze mixture
2. Compute binary ratio matrix
3. Identify separation techniques
4. Screen alternatives
5. Compute separation factor
6. Select the first separation task
7. Generate process flowsheet
8. Analyze decisions
9. Verify flowsheet
distillation
find solvents
determine design
parameters

14. Tasks to perform ?
9. Verify flowsheet
Description of a sample feasible flowsheet
T1
Reactor
FEED-T1
FEED
Molecular
Sieve
TOP-T1
H20-Purge
Mixer
TOP_NO_H2O
T2 T3
FEED-T2
TOP-T2
FEED-T3
Valve
TOP-T3
RECYCLE-T3
BOT-T3
MeAc 99.9%
BOT-T2
MeOH 98%
T4
T5 BOT-T5
HOAc 99.9%
BOT-T4
HOAc 99.9%
BOT-T1
TOP-T4
TOP-T5
P=6atm
P=1atm
P=6atm
P=1atm
P=1atm

15. Tasks to perform ? 9. Verify flowsheet
Verification (by simulation) of the flowsheet

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