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SEPARATION OF HETEROGENOUS

MIXTURE

POLITEKNIK PERKAPALAN NEGERI SURABAYA

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Introduction to Separation Processes

Separation process is used to transform a mixture ofsubstances into two or more distinct products.

The mixture can be a combination of any two or

more states: solid-solid, solid-liquid, solid-gas, liquid-

liquid, liquid-gas, gas-gas, solid-liquid-gas mixture, etc.

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Why Separations are needed?

Isolating valuable chemicals from mixtures Removing impurities from raw materials

Purification of products

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Separation Process Mechanisms

4

Phase creation

Phase addition

Barrier

Solid agent

External field

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Homogen Vs Heterogeneous Mixture

Pemisahan homogen:

a. Menciptakan fasa lain

b. Menambahkan agent pemisahc. Tidak dapat dilakukan secara

mekanik

Pemisahan heterogen:

a. Dipisahkan langsung secaramekanik

b. berdasarkan perbedaan

ukuran, bentuk atau

densitas

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Mechanical Separation

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Relatively less Energy Requirements

Ease of Operation

Ease of Maintenance

No special Feed pretreatment required

Not applicable for separating Components in homogeneous phase

Applicable to low flow rates

Advantages

Disadvantages

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Klasifikasi Pemisahan heterogen

On the basis of characteristics

Depending on the difference in size or shape

Depending on the difference in phase density

Depending on fluid and particle mechanics Depending on surface, electrical or magnetic properties

On the basis of phases involved

Gas-liquid (or Vapour-liquid)

Gas-solid (or Vapour- solid)

Liquid-liquid (immiscible)

Liquid-solid

Solid-solid

On the principal methods

Settling and Sedimentation

Inertial and centrifugal separationElectrostatic precipitation

Filtration

Scrubbing

Flotation

Drying

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Settling and Sedimentation

Force balance:

Settling: proses pemisahan particle dari fluida dengan

gaya gravitasi yang bekerja pada partikel

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Persamaan Kecepatan Settling

Zona settling Laminar

Zona settling transisi

Zona settling turbulent

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Settling Process

is usually taken to be a vessel in which the velocity of the gas (or vapor) is the terminal settling

velocity

for droplets of 100 m diameter

a. is usually taken to be a vessel in which the

terminal settling velocity for droplets of 100 m diameter

b. simple gravity settler or decanterfor removing a dispersed liquid phase from anotherliquid phase. The horizontal velocity must be low enough to

allow the low-density droplets to rise from the bottom. Decanters are normally

designed for a droplet size of 150 m but can be designed for droplets down to 100 m

c. gassolid particle separations, the size of the solid particles

is more likely to be known than the other types

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Thickener for liquid solid separation

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Gravity Settling Classifier

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Pemisahan Dengan Sentrifugasi

siklon Hidrosiklon

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Pemisahan Dengan Medan luar

Medan listrik (Electrostatik presipitator

Magnetic field

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Contoh Soal

1. Solid particles with a size 100 m are to be separated from

larger particles in a settling chamber. The flowrateof gas is 8.5

m3s1. The density of the gas is 0.94 kgm3and its viscosity

2.18 105kgm1s1.The density of the particles is 2780

kgm3

a. Calculate the settling velocity, assuming the particles are

Spherical

b. The settling chamber is to be box-shaped, with a rectangular

cross section for the gas flow. If the length and breadth of thesettling chamber are equal, what should the dimensions of the

chamber be for 100% removal of particles 100 m? assume

length = breadth

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Contoh Soal

2. A liquidliquid mixture containing 5 kgs1

hydrocarbonand 0.5 kgs1water is to be separated in a decanter. The

physical properties are given

The water can be assumed to be dispersed in the

hydrocarbon.

Estimate the size of decanterrequired to separate the

mixture in a horizontal drum with a length to diameter ratio

of 3:1 and an interface across the center of the drum

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Soal latihan

1. Gravity settler digunakan untuk memisahkan partikeldengan ukuran rata-rata 75 mikron dari gas denganflowrate 1,6 m3/s. densitas partikel 2100 kg/m3 .viscositas gas 1,85 x10-5 kg/ms dan densitasnya 1,18kg/m3. estimasi dimensi dari settling chamber dengan

mengasumsikan luas penampangnya berbentuk persegipanjang dengan panjang= 2xlebar nya ? (ganjil)

2. Decanter untuk memisahkan minyak dengan air. Dimana

aliran masuk terdiri campuran 6 kg/s air dan 0,6 kg/sminyak. Asumsikan air sebagai fase kontinyu. Rasio L/D=3.estimasi dimensi dari dekanter untuk memisahkan dropletair dengan diameter rata2 150 mikron? (genap)

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Fluid property soal 2

3. Jelaskan cara kerja (sertai dengan gambar) dari pemisahan

dengan metode:a. Filtrasi dan scrubbing (ganjil)

b. Flotasi dan drying (genap)