sentrifugasi

(1)

SENTRIFUGASI

28/02/2017 Nur Istianah-T.Separasi-

Sentrifugasi-2017

(2)

Sentrifugas i

Proses pemisahan solid dari liquid dengan prinsip

grafitasi ^. Densitas solid harus lebih besar dari densitas liquid

Sentrifugasi-2017

Peran gaya sentrifugal:

1. Mendorong partikel kecil agar mengendap 2. Menahan brownian motion

3. Mencegah arah free convection fluida

4. Mengurangi penumpukan “cake” pada screen (untuk

centrifugal filtration)

(3)

28/02/2017 Nur Istianah-T.Separasi- Sentrifugasi-2017

General principle

(4)

3

Sentrifugasi-2017

Klasifikasi centrifuge

Kapasitas

Labratory centrifuge

Preparative centrifuge

Kegunaan

Sedimenting centrifuge

Filtering centrifuge Ultracentrifugation

 Tubular bowl

 Basket

 Disk stack

 Scroll decanter

 Basket

 Pusher

 Baffle

 Inverting bag

 Cone screen

(5)

8

Sentrifugasi-2017

centrifugal filtration

1 centrifugal settling

2

(6)

Ultracentrifugation

1000-15000 rpm

Digunakan untuk pemisahan atau analisa campuran makromolekul

(AUC). Ex: protein

Rpm tinggi

menimbulkan

panas sehingga

memerlukan

cooling

(7)

Ultracentrifugation

separating

macromolecules from solvents

fractionating mixtures of macromolecules

studying the properties of

macromolecules

Analyzing complex mixtures of

macromolecules

(8)

(9)

(10)

(11)

(12)

Persamaan pada sentrifugasi

Sentrifugasi-2017

(13)

Persamaan pada centrifuge settling

(14)

Centrifugation time

• Time taken by the particle to move though the liquid layer is called residence time (t _r ).

dt V _t  dr

Nur Istianah-T.Separasi- Sentrifugasi-2017 28/02/2017

(15)







18 )

( ²

2 D r

v _t ^s  ^s









18 )

2 (

2 

 D ^s r ^s dt

dr

(16)

) (

ln 18

18 ) ln (

18 ) 1 (

2 2

1 2 2

2 1 2

0 2

2 2

1 

















 

 



  



s s

r

r s

s

t s

s r

r

D

r r t

D t r

r

D dt r dr

2 Nur Istianah-T.Separasi- 3

Sentrifugasi-2017 28/02/2017

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Calculation of flow rate for continuous centrifuge

• flow rate (Q)

1 2

2 2 2

1 2

2

1 2 2

2

2 2

1 2

ln 18

) (

ln 18

) (

ln 18

r r D b

r r

r r D

Q V

D

r r V t

Q V

s s

r

























 



 





(18)

• r

₁

= inside radius (m)

• r

₂

= outside radius (m)

• b = height of centrifuge(m)

• µ = viscosity (Pa.s)

• ω = an angular velocity (rad s

^-1

)

• ρ

_s

= density of solid (kg/m

³

)

• ρ = density of liquid (kg/m

³

)

• D

_s

= diameter of particle(m)

• V(m

³

)=operating volume of the centrifuge

Nur Istianah-T.Separasi- Sentrifugasi-2017

(19)

Example 1

Find centrifugation time t _r of a particle d=1mm. In a

centrifuge

Given

. 25 . 0

. 20 . 0

/ 1000

/ 1100

. 10

1 . 8

995 3 3 4

m R

m kg

s Pa RPM N

o i

f P













R

_i

R

_o

(20)

s rad

N

/ 20

. 104

60 995 2

60 2







 





 

Find ω

(21)

 

     

sec 10

25 . 3

1000 1100

20 . 104 001

. 0

) 20 . 0 / 25 . 0 ln(

10 1

. 8 18

) /

ln(

18

3 2 2

4 2

2 











 

 

r r

f p

i o

r

t t

d

r t r







Find time

t _r of particle d=1mm. in centrifuge≥3.25x10 ^-3 sec

(22)

Example 2

Beer with a specific gravity of 1.042 and a viscosity of 1.0 x10 ^-3 N s/m ² contains solids which have a density of 1160kg/m ³ . It is clarified at a rate of 240 l/h in a bowl centrifuge which has and operating volume of 0.09 m ³ and a speed of 10000 rev/min. The bowl has a diameter of 5.5 cm and is fitted with a 4 cm outlet. Calculate the effect on feed rate of an increase in bowl speed to 15000 rev/min and solid particle diameter at the higher speed.

(23)

• Solution

Initial flow rate

new flow rate

 

) /

ln(

18 ) 60 /

2 ( ₁ ² ²

1 i o

f p

r r

D N

Q V





 







 

) /

ln(

18 ) 60 /

2 ( ₂ ² ²

2 i o

f p

r r

D N

Q V





 







(24)

As all conditions except the bowl speed remain the same,

Therefore,

Q ₂ = 0.15 l/s

2 2 2

2 1

2 2

1 2

) 60 / 10000 142

. 3 2

(

) 60 / 15000 142

. 3 2

( )

3600 /

240 (

) 60 / 2

(

) 60 / 2

(



 



Q

N N Q

Q



(25)

To find the minimum particle size

m m

x D

V N

r r

D Q

f p

i o









18 . 0 10

8 . 1

09 . 0 ) 1042 1160

( ) 60 /

15000 14

. 3 2

(

)]

02 . 0 / 0275 .

0 ln(

10 0

. 1 18

[ 00015 .

0 ) (

) 60 /

2 (

)]

/ ln(

18 [

7 2 3 2

2 2 2







 

 



(26)

1 5

Sentrifugasi-2017

1 # A and B are dense and light liquid,

rA, rB =outlet radius

r

_n=

radius of neutral zone.

Fig 6.1. Separation of immiscible liquids

# t (s)=residence time ω = angular velocity, Q = volumetric flowrate,

V = operating volume of the centrifuge, D = diameter of the particle,

r

₂

= radius of light phase outlet, r

₁

= radius of dense phase outlet, N =speed of rotation

2

3 Separation of liquids

(27)

Example3

• A bowl centrifuge is used to break an oil- in-water emulsion. Determine the radius of the neutral zone in order to position the feed pipe correctly. (Assume that the density of the continuous phase is 1000 kg/m ³ and the density of the oil is 870 kg/m ³ . the outlet radius from the centrifuge are 3 cm and 4.5 cm).

(28)

• Solution

m r

r r

n n n

098 .

0

130 783 .

0 025

. 2

870 1000

) 03 .

0 ( 870 )

045 .

0 (

1000 ² ²

2 

 



 

(29)

Latihan soal

Dua buah sentrifuge digunakan pada kecepatan putar sama yaitu 53.34 m/s. Tentukan kecepatan putar dalam rpm dan gaya sentrifugal pada masing-masing sentrifuge untuk 1 kg feed jika:

Diameter sentrifuge pertama (D1) 15.24 cm Diameter sentrifuge pertama (D2) 61 cm 1

28/02/2017

(30)

Latihan soal

Sebuah centrifuge digunakan untuk memisahkan krim dengan jari-jari discharge 50.8 mm dan jari jari luar sentrifuge 76.2 mm. Densitas susu skim adalah 1032 kg/m ³ , densitas krim 865 kg/m ³ .

Hitunglah jari-jari zona netral pada sentrifuge!

2 r

_i

r

_o

50.8 mm

76.2 mm

28/02/2017

(31)

THANKS FOR YOUR ATTENTION

The best person is one give something useful always

Sentrifugasi-2017

sentrifugasi

SENTRIFUGASI

Sentrifugas i

Proses pemisahan solid dari liquid dengan prinsip

grafitasi . Densitas solid harus lebih besar dari densitas liquid

Peran gaya sentrifugal:

1. Mendorong partikel kecil agar mengendap 2. Menahan brownian motion

3. Mencegah arah free convection fluida

4. Mengurangi penumpukan “cake” pada screen (untuk

centrifugal filtration)

General principle

3

Klasifikasi centrifuge

Kapasitas

Labratory centrifuge

Preparative centrifuge

Kegunaan

Sedimenting centrifuge

Filtering centrifuge Ultracentrifugation

 Tubular bowl

 Basket

 Disk stack

 Scroll decanter

 Basket

 Pusher

 Baffle

 Inverting bag

 Cone screen

8

centrifugal filtration

1

centrifugal settling

2

Ultracentrifugation

1000-15000 rpm

Digunakan untuk pemisahan atau analisa campuran makromolekul

(AUC). Ex: protein

Rpm tinggi

menimbulkan

panas sehingga

memerlukan

cooling

Ultracentrifugation

separating

macromolecules from solvents

fractionating mixtures of macromolecules

studying the properties of

macromolecules

Analyzing complex mixtures of

macromolecules

Persamaan pada sentrifugasi

Persamaan pada centrifuge settling

Centrifugation time

• Time taken by the particle to move though the liquid layer is called residence time (t r ).

dt V t  dr









18

)

( 2

2 D r

v t s  s











18

)

2 (

2 

 D s r s dt

dr

) (

ln 18

18

) ln (

18

grafitasi ^. Densitas solid harus lebih besar dari densitas liquid

• Time taken by the particle to move though the liquid layer is called residence time (t _r ).

dt V _t  dr

( ²

v _t ^s  ^s

 D ^s r ^s dt