drying oil synthesis

8/16/2019 drying oil synthesis

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I

TABLE OF CONTENTS

CHAPTER PAGE

TABLE OF CONTENTS .............................................................................................................. 1

1a. PROCESS FLOW DIAGRAM ............................................................................................... 2

1b. STREAM TABLE ................................................................................................................... 31c. OVERALL UTILITY FLOW RATES AND DUTIES ................................................................. 4

1d. EQUIPMENT LIST ................................................................................................................ 5

2. DISCUSSION OF THERMODYNAMIC PROPERTIES AVAILABLE IN ASPEN ...................... 6

3. VALIDATING THE SELECTED THERMODYNAMIC MODEL ............................................7-10

4. LIST OF ASPEN MODEL LIBRARY COMPONENTS ...................................................... 11-13

5. APPENDICES .................................................................................................................. 14-24

6. REFERENCES ..................................................................................................................... 25



II

1a. PROCESS FLOW DIAGRAM

To storageT=30°CP=300 kpa


A B C FD E JH IG

A B C FD E JH IG

2

1

3

5

4

6

7

9

8

2

1

3

5

4

6

7

9

8

R-101REACTOR

P-101 A/BPRE-FURNACE

PUMP

F-101FURNACE

H-101CONDENSOR

HEATEXCHANGER

K-101KETTLE

REBOILER

C-102DISTILLATION

COLUMN

P-104 A/BREBOILER

PUMP

E-101REFLUXDRUM

P-102 A/BREBOILER

PUMP

H-102PRE-

DISTILLATIONCOLUMN

HEATEXCHANGER

H-106HEAT

EXCHANGER

C-101DISTILLATION

COLUMN

Sheet: 01/01

Date: 14/03/16

Project: P2

PFD- DRYING OIL PROCESS

Student Number: 50

CHE4049F

ACO

From storage tankT=80°CP=100 kpa

1

3

C-101

E-101

H-104

K-101

10

R-101

D-1016

5

GM


H-103CONDENSOR

E-102REFLUXDRUM

P-105 A/BREFLUXPUMP

H-104HEAT

EXCHANGER

K-102KETTLE

REBOILER

H-109HEAT

EXCHANGER

H-105HEAT

EXCHANGER

H-103

C-102

H-107

P-102 A/B

H-101

P-102 A/B

F-101

KEY

AA: ACETIC ACID

ACO: ACETYLATED CASTOR OIL

DO: DRYING OIL

GM: GUM

PG: PURGE

7

8

12 AA

13

15 16

DO

E-102

P-105 A/B

H-108

H-109

K-102

P-104 A/B

9

24

18 19

PG21

11

To waste disposalT=150°C

P=100 kpa

20

23

14

17

22

4

2

NG

P-101 A/B

H-102

P-106 A/B

P-107 A/B

P-108 A/B

P-109 A/B

H-105

H-106

D-101 A/BSEPARATOR

P-103 A/B

P-103 A/BREFLUXPUMP

H-107CONDENSOR

H-108HEAT

EXCHANGER

P-105 A/B ACETIC ACIDTO STORAGE

P-106 A/BGUM TOWASTE

DISPOSAL

P-108 A/BDO

TO STORAGE

P-107 A/BPURGEPUMP

Dowtherm A

Dowtherm A

CW

MPS

CW

MPS

MPS

CW

CW

CW

CW

Exhaust

P-109 A/BDO

TO STORAGE



III

1b. STREAM TABLE

1 2 3 4 5 6 7 8 9 10 11 12 13 AA 15 16 DO 18 19 GM 21 22 PRG RCY

T° C 80.0 80.0 227.3 340.0 258.8 105.0 105.0 150.0 120.2 141.0 350.0 118.0 30.0 30.6 242.3 30.0 30.5 105.0 150.0 150.2 350.0 80.0 80.1 350.0

P bar 1.000 1.013 1.013 1.013 1.013 1.013 1.013 1.068 1.013 1.786 1.013 1.013 0.027 3 1.013 0.001 3.000 1.013 0.000 1.000 1.013 <0.0001 1 1.013

Vapor Frac 0 0 0 0 0.49 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Mole Flow 5.85 5.85 11.96 11.96 17.11 17.11 17.11 17.11 10.32 10.32 6.79 5.12 5.12 5.12 5.20 5.20 5.20 0.001 0.001 0.001 0.68 0.68 0.68 6.11

kmol/hr

Mass Flow 1500 1500 3067 3067 3067 3067 3067 3067 1326 1326 1741 308 308 308 1018 1018 1018 0.265 0.265 0.265 174 174 174 1567

kg/hr

ACETI-01 0 0 0 0 309 309 309 309 309 309 0 307 307 307 1.97 1.97 1.97 0 0 0 0 0 0 0

1-TET-01 0 0 0 0 1011 1011 1011 1011 1011 1011 0 0.412 0.412 0.412 1011 1011 1011 0 0 0 0 0 0 0

1-OCT-01 0 0 0 0 0.265 0.265 0 0 0 0 0 0 0 0 0 0 0 0.265 0.265 0.265 0 0 0 0

N-HEX-01 1500 1500 3067 3067 1746 1746 1746 1746 5.00 5.00 1741 0 0 0 5.00 5.00 5.00 0 0 0 174 174 174 1567

WATER 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

DOWTH-01 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Mass Frac

ACETI-01 0 0 0 0 0.101 0.101 0.101 0.101 0.233 0.233 0 0.999 0.999 0.999 0.002 0.002 0.002 0 0 0 0 0 0 0

1-TET-01 0 0 0 0 0.330 0.330 0.330 0.330 0.763 0.763 0 0.001 0.001 0.001 0.993 0.993 0.993 0 0 0 0 0 0 0

1-OCT-01 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0

N-HEX-01 1 1 1 1 0.569 0.569 0.569 0.569 0.004 0.004 1 0 0 0 0.005 0.005 0.005 0 0 0 1 1 1 1

WATER 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

DOWTH-01 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Mole Flow

kmol/hr

ACETI-01 0 0 0 0 5.15 5.15 5.15 5.15 5.15 5.15 0 5.12 5.12 5.12 0.03 0.03 0.03 0 0 0 0 0 0 0

1-TET-01 0 0 0 0 5.15 5.15 5.15 5.15 5.15 5.15 0 0.002 0.002 0.002 5.15 5.15 5.15 0 0 0 0 0 0 0

1-OCT-01 0 0 0 0 0.001 0.001 0 0 0 0 0 0 0 0 0 0 0 0.001 0.001 0.001 0 0 0 0 N-HEX-01 5.85 5.85 12.0 12.0 6.81 6.81 6.81 6.81 0.019 0.019 6.79 0 0 0 0.019 0.019 0.019 0 0 0 0.679 0.679 0.679 6.11

WATER 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

DOWTH-01 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Mole Frac

ACETI-01 0 0 0 0 0.301 0.301 0.301 0.301 0.499 0.499 0 1 1 1 0.006 0.006 0.006 0 0 0 0 0 0 0

1-TET-01 0 0 0 0 0.301 0.301 0.301 0.301 0.499 0.499 0 0 0 0 0.99 0.99 0.99 0 0 0 0 0 0 0

1-OCT-01 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0

N-HEX-01 1 1 1 1 0.398 0.398 0.398 0.398 0.002 0.002 1 0 0 0 0.004 0.004 0.004 0 0 0 1 1 1 1

WATER 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

DOWTH-01 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0



IV

1c. OVERALL UTILITY FLOW RATES AND DUTIES

Equipment Utility type Tin utility Tout utility Pressure (bar) Duty Usage

°C °C °C MW kg/hr

FURNACE (F-101) DOWTHERM-A 400 370 5 0.292 16700

RADFRAC1(C-101) DOWTHERM-A 400 370 5 0.629 36000

RADFRAC2(C-102) DOWTHERM-A 400 370 5 0.171 9790

TOTAL 1.09 62500Equipment Utility type Duty Usage

MW kg/hr

COOLER (H-106) COOLING WATER 20 25 1 0.037 6380




TOTAL 0.618 106600

Equipment Utility type Duty Usage

MW kg/hr

HEATER (H-102) MPS 175 174 8.76 0.0928 167

HEATER (H-104) MPS 175 174 8.76 0.0172 30.9

HEATER (H-105) MPS 175 174 8.76 8E-06 0.0142

TOTAL 0.1100 198

OVERALL UTILITY FLOWRATE 169300



V

1d. EQUIPMENT LIST PFD Code Equipment Type Equipment Specifications

PUMPS P-101 - 9 A/B Centrifugal/electric drive/API Stainless steel/corrosion resistance & and high T

HEAT H-101 1-2 Heat exchanger/Process Shell side Q=-0.42MW, Stainless Steel, 0.625 -1.5’’ tubes

EXCHANGERS H-102 1-2 Heat exchanger/Process Shell side Q=0.093MW, Stainless Steel, 0.625 -1.5’’ tubes

H-103 1-2 Heat exchanger/Process Shell side Q<0.0001MW, Stainless Steel, 0.625 -1.5’’ tubes

H-104 1-2 Heat exchanger/Process Shell side Q=0.017MW, Stainless Steel, 0.625 -1.5’’ tubes

H-105 1-2 Heat exchanger/Process Shell side Q<0.0001MW, Stainless Steel, 0.625 -1.5’’ tubes

H-106 1-2 Heat exchanger/Process Shell side Q=-0.0.037MW,Stainless Steel, 0.625 -1.5’’ tubes H-107 1-2 Heat exchanger/Process Shell side Q<0.0001MW, Stainless Steel, 0.625 -1.5’’ tubes

H-108 1-2 Heat exchanger/Process Shell side Q=-0.0099MW, Stainless Steel, 0.625 -1.5’’ tubes

H-109 1-2 Heat exchanger/Process Shell side Q=-0.15MW, Stainless Steel, 0.625 -1.5’’ tubes

DISTILLATION C-101 Total Condenser and Kettle Reboiler Reflux Ratio=0.9, Boil up Ratio=5.17, FS=11

COLUMNS Sieve trays and Stainless steel shell Column pressure=1 ATM

Column diameter=2.1m, Column height=15.2m

Number of stages=22

C-102 Total Condenser/Kettle Reboiler RR=2, BR=1.02, FS=9

Sieve tray and Stainless steel shell Column pressure=1 ATM

Column diameter=1.9m, Column height=12.8m

Number of stages=18

FURNACE F-101 Carbon steel tubes, Refractory lining Q=1.05E+0.6KJ/hr, Texit=340°C

REACTOR R--101 Stainless steel PFR/ Adiabatic L=9m, D=10m, X=0.42

REFLUX DRUM E-101 Stainless steel vessel Hold up time=5min whilst half full

E-102 Stainless steel vessel Hold up time=5min whilst half full

REBOILER K-101 Kettle type/ Dowtherm A Boil up Ratio=5.17; T=400˚C, P=5bar

Boil up rate= 35.1kmol/h

K-102 Kettle type/ Dowtherm A Boil up Ratio=1.02; T=400˚C, P=5bar

Boil up rate = 5.3kmol/hr

SEPARATION COLUMN D-101 Vertical vessel L/D=5, V=3m3 (Bailie & Whiting 2012)



VI

2. DISCUSSION OF THERMODYNAMIC PROPERTY METHODS AVAILABLE IN ASPEN

Aspen Plus Version 8.8 has a wide range of physical ‘Property Methods’ to choose from.

Selecting the right thermodynamic model is the first step and most important decision when

carrying out a chemical process simulation(Hill & Justice 2011). The main model categories are

Equations of State models (EOS), Activity Coefficient Models, Predictive Activity Models and

Electrolyte models.

Equation of state models are based on the specification of pure substances such as boiling

point, critical conditions, and acentric factors. Frequently used EOS models are Soave Redlich

Kwong and Peng Robinson. These are great for modelling light gases, similar hydrocarbons

and petroleum pseudo-components (Hill & Justice 2011). Equation of state models can

compute information on compressibility of gases. EOS models are used for real gases and

ideal liquid systems (Sandler, 2006).

Activity Coefficient Models are also known as Binary Interaction Parameter (BIP) models. NRTL

and Wilson are examples of Activity Coefficient models, and are most commonly used for water

and different hydrocarbon compounds like alkanes and alkenes (Hill & Justice 2011).Furthermore, different organic molecules like ester and alcohols are modelled well by activity

coefficient models. These models calculate activity from binary interaction parameters gleaned

from empirical data. The parameters are extracted from experimental data by regression

methods. In situations where an activity coefficient model does not have Binary Interaction

Parameters, a predictive activity coefficient model is required.

UNIFAC and UNIQUAC also fall under the Activity coefficient category. However, they are set

apart as Predictive Activity Coefficient models. They require group interaction parameters

obtained from sub groups on the molecule. The notion behind a predictive approach is that a

molecule is the sum of its ‘smaller parts whose interactions are known’ (Hill & Justice 2011).

Further developments to these models in Aspen are UNIF-HOC and UNIQ-HOC. UNIF-HOCand UNIQ-HOC were developed to handle dimerization(Liu et al. 2015). (Sandler, 2006)

advises the use of UNIFAC when there is no experimental data is available.

Another model category found in Aspen is for electrolytes. The most commonly used model for

electrolyte based systems is NRTL(Hill & Justice 2011). Examples of aqueous electrolyte type

systems are: water and acid systems, and base or salt systems.

Most applications involve liquid solvents. Henry’s Law makes comes with the assumption of

infinite dilution, even though most systems never get to that state. The non-linear temperature

dependence of Henry’s constant must be taken into account for accurate process design

(Smith & Harvey 2007).



VII

3. JUSTIFYING THE SELECTED THERMODYNMIC MODEL

In order to choose the right thermodynamic model for the drying oil process simulation, the first

step is to understand the nature of the mixture. Appendix A shows the molecular structures of

acetic acid, drying oil (1-tetradecene), acetylated castor oil (N-hexadecanoic acid) and gum (1-

Octacosene). Drying oil and gum are alkenes whilst acetic acid and acetylated castor oil are

carboxylic acids.

It is understood that drying oil has a tendency to dimerize and form gum(Bailie & Whiting 2012).

Furthermore, it is also known that acetic acid has a tendency to dimerize as well (Fujii et al.

1988). Basic chemistry knowledge points to the fact that carboxylic acids form dimers by means

of hydrogen bonds. This often occurs in the vapour phase. In conclusion, the mixture is highly

polar because of the hydrogen bond interactions between the carboxylic acid molecules and

dimerization that occurs to some extent. This is a highly non ideal and polar mixture. There is

no random distribution of molecules in polar solutions (Sandler, 2006)

With this knowledge in mind it is important to find thermos-physical properties of the

compounds involved and generate several T-X-Y and P-X-Y diagrams to validate thethermodynamic model(Hill & Justice 2011). These diagrams can be found in APPENDIX B and

APPENDIX C.

Figure 2, Figure 4 and Figure 7 in APPENDIX B depict how the UNIFAC, WILSON AND UNIF-

HOC models are good approximations of vapour equilibrium data by (Matricarde Falleiro et al.

2010). Furthermore, an X-Y plot can also be used to determine if ASPEN can identify the

formation of an Azeotrope at the operating conditions of the system.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.2 0.4 0.6 0.8 1

Y - N

- T E T R A D E C A N O I C

A C I D

X-TETRADECANOIC ACID

FIGURE 1: EXPERIMENTAL DATA (Matricarde Falleiro et al, 2010)COMPARED TO ASPEN MODELS

EXPERIMENTAL DATA

Equilibrium Line

UNIFAC

PENG ROBINSON

PRSK

NRTLUNIF-HOC



VIII

The experimental data from the (Matricarde Falleiro et al. 2010) was plotted against

thermodynamic models from ASPEN and Figure 1 was the result. The experimental data was

obtained by using differential scanning calorimetry. The experiment involved palmitic acid

(hexadecanoic acid), which is what we are using as a model for acetylated castor oil, and

myristic acid (tetradecanoic acid) which can be modelled as a similar molecule to drying oil

( See APPENDIX A).

Similar compounds are used to model reactants in the drying oil process in the situation where

plant data, pilot plant data and laboratory data may not be readily available. Therefore palmitic

acid is used to model acetylated castor oil while myristic acid is used as a model to drying oil.

Their similarities are shown in APPENDIX A.

In order to understand the absolute fit of ASPEN models to VLE data provided by (Matricarde

Falleiro et al. 2010), Table 1 shows the results of a root mean square error analysis.

Thermodynamic Model RMSE ValueUNIFAC 0.00639

UNIF-HOC 0.00671

UNIQUAC 0.00570

WILSON 0.00540

NRTL 0.00547

PENG ROBINSON 0.01151

PRSK 0.00587

Table 1: Root mean square error analysis.

The result from Table 1 shows how UNIFAC, UNIF-HOC, UNIQUAC, WILSON AND NRTL

models are a good fit to the vapour liquid equilibria data of palmitic acid and myristic acid.

The P-X-Y diagrams were generated from data for hexene and acetic acid. This data was

obtained from the NIST database provided by ASPEN. Hexene is used to model drying oil.

Hexene is a shorter chain alkene to 1-tetradecene (drying oil), therefore it can be argued that

they have similar properties to a certain extent. The P-X-Y diagrams in APPENDIX C (data at

224 degrees Celsius; Pressure range 12 to 31 bar)) alert us to the possibility of an azeotrope at

those conditions. However, granted that the simulation of the drying oil process in this project is

done at 1 atmosphere this maybe unlikely. ASPEN generated a report (APPENDIX D) showing

that no azeotropes are formed at 1 atmosphere.



IX

T-XY AND P-XY diagrams are plotted to understand the nature of the process mixture and the

ease of separation (Sandler 2006). In selecting the thermodynamic model for this project

recommendations from literature were considered. An attempt was made to find a simulation

model that has been used for an actual drying oil process plant. The search for this was

unsuccessful. The next step was to find thermodynamic models that have been frequently used

for the simulation of the drying oil process. This information was also not found. Thereforeliterature was sought to fill in the gap. It was clear that Wilson and NRTL are the obvious choice

for mixtures containing strongly polar compounds and alkenes. It is mentioned in literature that

a mixture containing ‘components from more than one class exhibits greater non-ideality’

(Sandler, 2006). Therefore the use of Wilson is highly recommended. However, vapor

equilibrium data for the compounds used in the drying oil process was difficult to find. Plant

data, pilot plant data, laboratory data and even literature data for the drying oil process could

not be easily accessed or found. As a result a predictive model was chosen.

Experienced process engineers and proffessors were consulted. They agreed with ( Sandler,

2006) who recommends that when no experimental data is available UNIFAC should be used.

The notion behind a predictive approach is that a molecule is the sum of its ‘smaller partswhose interactions are known’ (Hill & Justice 2011). Therefore UNIFAC was the chosen model

for this project.

Aspen recommends UNIFAC-HOC which may have the added advantage of accounting for

dimerization. However, it is good to take advice from experienced process simulation engineers

and that is why UNIFAC was used. Literature upholds this prudent reasoning. UNIFAC may be

an older version than UNIFAC-HOC, but it is great as an init ial i terat ion . How can UNIFAC be

validated for the drying oil process? A simple flash separation performed can verify that the

vapour liquid separation that occurs with the mixture from the reactor is in line with expectations

from experienced engineers (Hill & Justice 2011). An inappropriate model will yield wrong

results. Figure 9 below shows a comparison of activity coefficient data from a solubility data setby (Ralston & Hoerr 1942) and ASPEN thermodynamic models(see calculation in APPENDIX

D). UNIFAC is a good approximation of the experimental data. Figure 2 also validates that

UNIFAC is an appropriate model to simulate the drying oil process.



X



XI

4. MODEL LIBRARY COMPONENTS

MODEL LIBRARY COMPONENTS PFD Code Equipment TypePUMPS P-101 A/B Centrifugal/electric drive/API

P-102A/B Centrifugal/electric drive/API








HEAT H-101 Cooler

EXCHANGERS H-102 Heater

H-103 Condenser

H-104 Heater

H-105 Heater

H-106 Cooler

H-107 Condenser

H-108 Cooler

H-109 Cooler

DISTILLATIONCOLUMNS C-101 Distillation column

C-102 Distillation column

FURNACE F-101 Natural gas furnace

REACTOR R--101 Plug flow reactor

REFLUX DRUM E-101 Reflux drumE-102 Reflux drum

REBOILER K-101 Kettle type

K-102 Kettle type

SEPARATION COLUMN D-101



XII

MODEL LIBRARY

COMPONENTS FUNCTION

PUMPS

P-101 A/B Pump liquid ACO from storage tanks and charge it into the process.

P-102A/B Pumping of the column’s bottoms liquid to the kettle reboiler.

P-103A/B Condensers are not located at the top of columns, reflux and distillate is pumped up.

P-104A/B Pumping of the column’s bottoms liquid to the kettle reboiler .P-105A/B Condensers are not located at the top of columns, reflux and distillate is pumped up.

P-106A/B Gum needs to be pumped to storage. Gum exits process as a liquid at a pressure of 100kpa.

P-107A/B 0.1 percent of recycled ACO with trace products is purged and pumped out to storage at 100kpa.

P-108A/B The product DO needs to be pumped from the second columns bottoms stream to storage at 300kpa.

P-109A/B The distillate AA has to be pumped from the distillate stream to storage at 300kpa.

HEAT EXCHANGERS

H-101 Reactor products exit extremely hot. Energy from this stream can be used to generate lps from bfw.

H-102 Stream entering C-101 needs to be heat to get to the bubble point of the liquid mixture.

H-103 This is a total condenser.

H-104 Stream entering C-102 needs to be heat to get to the bubble point of the liquid mixture.

H-105 This is a heater used to melt the accumulated gum before it is pumped to waste disposal.

H-106 Recycled ACO coming from the bottoms of C-101 is hot liquid and needs to be cooled before purging.

H-107 This is a total condenser.H-108 The distillate stream needs to cooled to a temperature of 30˚C before AA is pumped to storage.

H-109 The bottoms stream needs to be cooled before DO is pumped to storage at 30˚C.

DISTILLATION

COLUMNS

C-101 Radfrac columns can handle highly non ideal components. Radfrac is more rigorous than DISTWU.

C-102 Radfrac columns can handle highly non ideal components. Radfrac is more rigorous than DISTWU.

FURNACE

F-101 Reactor inlet temperature T=340˚C is higher than the temperature of HPS at 4237kpa (253.794K).

REACTOR



XIII

R--101 PFRs are adequate for high throughput and short residence time reactions. Adiabatic reactor used.

REFLUX DRUM

E-101 Hold up time of 5 minutes when half full and these are good for limiting phase entrainment.

E-102 Hold up time of 5 minutes when half full and these are good for limiting phase entrainment.

REBOILER

K101-102 More volatile components in the bottoms product need to be stripped.



XIV

APPENDIX A

MOLECULAR STRUCTURE

ACETIC ACID

1 TETRADECENE (DRYING OIL)

MYRISTIC ACID (1 TETRADECANOIC ACID)



XV

1 OCTACOSENE (GUM)

N-HEXADECANOIC ACID (ACETYLATED CASTOR OIL)

PALMITIC ACID (HEXADECANOIC ACID)

HEXENE



XVI

APPENDIX B

T-XY DIAGRAMS



XVII



XVIII



XIX



XX

APPENDIX C

P-XY DIAGRAMS



XXI



XXII

APPENDIX D

CALCULATING THE ACTIVITY COEFFICIENT

T (K) T °C C/L (mol/mol)

293.15 20 0.0049866

303.15 30 0.0186385

313.15 40 0.107998

323.15 50 0.422967

333.15 60 0.842257

Table 2: Solubility of hexadecanoic acid as a function of temperature (Ralston & Hoerr 1942)

In order to calculate the activity coefficient (gamma) the following equation from (Sandler, 2006)

was used:

Notice the above equation has three terms on the RHS. Each term will be calculated using CP

and temperature data from (Ralston & Hoerr 1942). This data is shown in Table 1 above.

The following steps were taken to calculate gamma in EXCEL:

T (K) CpL (J/g.K) CpL (J/mol.K)

343 2.18 559

348 2.21 567

353 2.25 577

358 2.33 597

363 2.38 610

368 2.45 628373 2.49 638

378 2.55 654

383 2.62 672

388 2.7 692

393 2.71 695

398 2.77 710

403 2.83 726

408 2.88 738

413 2.95 756

418 3.04 780423 3.1 795

428 3.17 813

Table 3: Heat capacity data for hexadecanoic acid (source: http://webbook.nist.gov)

The following graph was then generated in order to obtain the gradient and intercept values.



XXIII

Obtaining the gradient and intercept from the relationship between Cp(l) and temperature.

The following information necessary for the calculation was also obtained from

(http://webbook.nist.gov/cgi/cbook.cgi?ID=C57103&Mask=2)

Data: N-hexadecanoic acid Value Units

Molecular weight 256.42 g/mol

Ideal gas constant: R 8.314 J/mol.k

Heat of fusion 53642.3 J/mol

T(melting) 335.64 K

Table 4: Properties of N-hexadecanoic acid.

The following information was then used to appreciate the change in heat capacity.

Which is the difference between the heat capacity of the liquid and that of the solid

ΔCp= Cp(l) – Cp(s)

ΔCp= gradient*T + constant

The gradient and constant are displayed by Figure 19.

This information was then used to compute the right hand side of the equation from (Sandler,

2006)

The second and third terms required integration.

http://webbook.nist.gov/cgi/cbook.cgi?ID=C57103&Mask=2






XXIV

RIGHT HAND SIDE

OF EQUATION

1ST TERM 2ND TERM 3RD TERM TOTAL

-2.786 -0.757 0.708 -2.835

-2.060 -0.551 0.524 -2.087

-1.381 -0.364 0.352 -1.393

-0.743 -0.193 0.189 -0.747

-0.144 -0.037 0.037 -0.144

Table 5: Calculating the the right handside of ln(xi*gamma) equation from (Sandler, 2006)

Once these values were obtained the gamma was made the subject of the formula and the following data was computed:

T (K) T °C C/L (mol/mol) EXPERIMENTAL UNIFAC UNIF-HOC UNIQUAC UNIQ

293.15 20 0.005 11.8 2.42 2.53 0.47

303.15 30 0.019 6.65 2.34 2.45 0.47

313.15 40 0.108 2.30 2.27 2.37 0.47

323.15 50 0.423 1.12 2.20 2.30 0.47

333.15 60 0.842 1.03 2.13 2.22 0.47

T (K) T °C C/L (mol/mol)

EXPERIMENTA

L

WIL

SON NRTL

PEN

G

ROBINSON 293.15 20 0.005 11.8 1 1 71.6

303.15 30 0.019 6.65 1 1 49.2

313.15 40 0.108 2.30 1 1 34.9

323.15 50 0.423 1.12 1 1 25.4

333.15 60 0.842 1.03 1 1 18.9

Table 5: EXPERIMENTAL VALUES OF GAMMA COMPUTED FROM USING EQUATION 1 FROM (SANDLER, 2006) AND

SOLUBILITY DATA FROM (Ralston & Hoerr, 1942)

Table 5 shows the experimental values of gamma obtained from solubility data from (Ralston & Hoerr, 1942).

These experimental values were then compared to different models from ASPEN.





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