Separation Column in Chemcad

Agung Ari Wibowo, S.T., M.Sc

Politeknik Negeri Malang

Malang - Indonesia

The use of separation column in Chemcad

The separators in chemcad can beused to model a wide variety ofchemical separation techniquesincluding liquid-liquid extraction anddistillation

Shortcut distillation The primary purpose of the shortcut distillation is to allow for

users to perform a first pass estimate on the performance

requirements of a given system for a specified reflux ratio. The

values gathered from the shortcut distillation utility can be used

to assist the user when setting up the complete distillation utility

in chemcad, or when attempting to find reasonable column

properties to allow the system to converge (e.g. number of

trays, feed location, etc.)

The shortcut distillation utility within HYSYS allows users to

quickly model a distillation separation of a stream with relatively

little known information. Once the user attaches a fully defined

inlet stream to the shortcut distillation column, the essential

information that must be specified are as follows:

The vapor/liquid quality of the top product

The light key component and composition in the bottoms product

The heavy key component and composition in the distillate (top)

product

The column pressure

The external reflux ratio

Shortcut distillation

What is Light and Heavy Key?

Light Key : a lighter component means a component with alower boiling point. Defined as lightestcomponent in the bottom product in asignificant amount

Heavy key : a heavier component means a component with ahigher boiling point. Defined as heaviestcomponent in the overhead product in asignificant amount.

*Note : Both Light and Heavy key depend on the componentin the stream

Shortcut distillation

With this information, the utility will run and, if possible, converge on a solution that

will meet the key component specifications. The critical information that the utility

will calculate are as follows:

Fully specified distillate product stream (temperature, pressure, flow rate,

composition)

Fully specified bottom product stream (temperature, pressure, flow rate,

composition)

Condenser operating temperature and heat duty

Reboiler operating temperature and heat duty

Minimum number of trays (calculated by Fenske Methode)

Actual number of trays (minimum/theoritical tray devided by tray efficiency)

Optimum feed tray location

Reflux minimum (Calculated by Underwood Methode)

Shortcut distillation

A distillation column is used to separate mixed compound of Benzene,

Toluene and o-xylene. Feed entering to the column at 20°C and 1 atm

with mass flow 500 kg/hr. The attempt of this separation process is to

get benzene with purity of 99% (top product only Benzene and

Toluene) . And the benzene composition at the bottom will be 1%. If

the column operate isobarically and R= 1.18 Rm. What is the

composition of the product (top and bottom), and what is the

temperature of reboiler (Use Peng-Robinson as Fluid Package)?

Case

Feed Composition Mole Fraction

Benzene 0.35

Toluene 0.25

o-xylene 0.40

Case

Case

Simulation Result

STREAM

PROPERTIES

Stream No. 1 2 3

Name

- - Overall - -

Temp C 25 80.2621

127.599

9

Pres kPa 101.3 101.3 101.3

Enth kJ/h 56394

1.07E+0

5 32688

Flow rates in kg/h

Benzene

147.238

9

145.766

5 1.4724

Toluene

124.056

3 1.2406

122.815

7

O-Xylene

228.704

8 0

228.704

8

Case

Case

Simulation: Untitled

STREAM PROPERTIES

Stream No. 4 5 6

Name

- - Overall - -

Temp C 20 81.3351 124.7207

Pres kPa 101.3 101.3 101.3

Enth kJ/h 31630 75380 45006

Vapor mole fraction 0 0 0

Molar flow kmol/h 5.3053 1.3695 3.9359

Mass flow kg/h 500 108.1317 391.8683

Std liq m3/h 0.568 0.1224 0.4456

Std vap 0 C m3/h 118.912 30.6948 88.2173

Flow rates in kg/h

Benzene 103.6054 100.5309 3.0745

Toluene 171.0938 7.6008 163.493

O-Xylene 225.3009 0 225.3009

`

Case 2

Ethyl benzene is produced by the reaction of ethylene and benzene. The

reactor which being used has the maximum conversion of 80% and operated

adiabatically. The feed of the reactor consist of pure ethylene, benzene and

recycle stream from Flash Separator. The product from the reactor is cooled to

64 C, and then flash separated. The bottom product of the Flash Separator will

be separated using distillation column to get high purity E-benzene. If the

column bottom product only consist of Benzene and E-benzene in which the

mole fraction of benzene is 0.1% and in the Top product the mole fraction of

E-Benzene is 0.01%, determine in which stage feed should enter the column?

Column operated isobarically.

C2H4 + C6H6 →C8H10

Component Benzene Ethylene

Temperature (C) 25 25

Pressure (atm) 1 1

Molar Flow (kmol/hr) 500 450

Fluid Package (Peng-Robinson)

R = 1.26 Rm Distillate Phase : Liquid

Mass & Eneergy Balance ResultSTREAM PROPERTIES

Stream No. 1 2 3 4 5 6 7 8 9 10

Name

- - Overall - -

Temp C 25 25 11.2036 276.9597 64 135.837 25 64 64 -27.4237

Pres kPa 101.3 101.3 101.3 101.3 101.3 101.3 101.3 101.3 101.3 101.3

Enth kJ/h 2.51E+07 2.35E+07 4.86E+07 4.86E+07 1.19E+07 3.80E+06 -3.83E+06 5.48E+06 6.44E+06 5.48E+06

Vapor mole fraction 0 1 0.5029 1 0.1888 0 0 0 1 0

Molar flow kmol/h 500 450 950 590 590 350.0963 350.0963 478.5945 111.4054 128.4983

Mass flow kg/h 39057 12624.3 51681.3 51680.94 51680.94 37134.35 37134.34 47079.11 4601.831 9944.77

Std liq m3/h 44.1622 36.0695 80.2317 63.4198 63.4198 42.5935 42.5935 54.0297 9.3902 11.4362

Std vap 0 C m3/h 11206.82 10086.14 21292.97 13224.05 13224.05 7846.935 7846.935 10727.05 2497.002 2880.116

Flow rates in kg/h

Benzene 39057 0 39057 10935.96 10935.96 95.5887 95.5887 9558.85 1377.106 9463.263

Ethylene 0 12624.3 12624.3 2524.86 2524.86 0 0 107.377 2417.483 107.3771

Ethylbenzene 0 0 0 38220.13 38220.13 37038.75 37038.75 37412.88 807.2421 374.1289

Absorption Column

Proses absorpsi gas adalah proses dimana komponen gas yang ada

dalam suatu campuran ditransfer ke bagian liquid absorbent.

Kebalikan dari proses ini dinamakan proses stripping. Tujuan dari

peralatan absorpsi adalah menyediakan kontak secara langsung dan

baik antara liquid dengan gas, sehingga bisa memfasiltasi proses

tersebut dengan baik. Selain jenis packed tower, jenis perlatan yang

bisa digunakan adalah buble-plate tower, cooler-absorber dan spray

tower. Konvergensi dari simulasi kolom absorpsi pada ChemCAD

tergantung dari komposisi umpandan kondisi operasi dari kolom.

Absorption Column

Typical Flowsheet of Absorption

Absorption Column

PPAQ : K-Value Method for Ionic compound which dissolve in water and disassociate e.g NH3, HCl, HNO3

Absorption Column

Absorption Column

Simulation: Absoprsi HCl-Water

STREAM PROPERTIES

Stream No. 1 2 3 4

Name

- - Overall - -

Temp C 45 45 44.93 40.8071

Pres kPa 101.3 101.3 101.3 101.3

Enth kJ/h -7347.7 -4.74E+05 -8040.1 -4.73E+05

Vapor mole fraction 1 0 1 0

Molar flow kmol/h 0.4304 1.6653 0.3822 1.7134

Mass flow kg/h 13 30 10.615 32.3851

Flow rates in kg/h

Water 0 30 0.615 29.385

Oxygen 2 0 2 0

Nitrogen 8 0 8 0

Hydrogen Chlorid 3 0 0 3

ExtractionColumn

The Extraction module calculates the heat and material balance of a stagewisecontacting of two immiscible liquid mixtures. This unit permits up to five feeds and six products. This UnitOp allows up to 300 stages and accommodates stage efficiencies. The EXTR module uses the Newton-Raphson simultaneous convergence technique for its solution.

ExtractionColumn

ExtractionColumn

Simulation: Extraction Water+Acetone+Benzene

STREAM PROPERTIES

Stream No. 1 2 3 4

Name

- - Overall - -

Temp C 25 25 25.0002 25

Pres kPa 101.3 101.3 101.3 101.3

Enth kJ/h -2.71E+05 49125 -54842 -1.67E+05

Vapor mole fraction 0 0 0 0

Molar flow kmol/h 1 1 1.4157 0.5843

Mass flow kg/h 34.041 78.114 101.614 10.541

Flow rates in kg/h

Water 10.809 0 0.2863 10.5227

Acetone 23.232 0 23.232 0

Benzene 0 78.114 78.0957 0.0183

Thank You