exp 5 baffle turbine

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EXPERIMENT # 12

Date: 16-12-2013

OBJECT

Perform the operation of mixing and show an analysis of eects of

dierent sizes of turbine on mixing.

THEORY

Mixing is one of the common operations carried out in the chemical

processing and allied industries. The term mixing is applied to the processes

used to reduce the degree of non-uniformity, or gradient, a property in a system

such as concentration, viscosity, temperature and so on. Mixing is achieved by

moving materials from one region to another. t may be of interest simply as a

means of achieving a desired degree of homogeneity but it may also be used to

promote heat and mass transfer, often where a system is undergoing a chemical

reaction.

APPARATUS

Mixing tan!, variable speed motor, dierent size turbines, ba"es, p#

meter and small bea!ers.

PROCEDURE

$dd water so that the height becomes e%ual to the diameter of the tan!.

Ta!e four ba"es all should be of same size.

&tart the motor and add concentrated base.

$fter every '( seconds, ta!e out a sample of about )*ml. $fter each sample, add )*ml water so that the level of water remains

constant.

+hile !eeping the speed at optimum. epeat the experiment for dierent

size turbines.

raw graph for the change in p# for each turbine size. etermine the

optimum turbine size.

&cale up the results times.

OBSERVATIONS

200 Rpm and 2.2cm bafe with

5cm turbine size

200 Rpm and 2.2 cmbafe with 6cm

turbine size

200 Rpm and 2.2 cmbafe size with 7cm

turbine size


2/5

Time/sec0 p#

* .12

'( '*.3

)* '*.42

3( '*.43

1* '*.41

5( '*.41

4* '*.45

'*( '*.4

'2* '*.4

')( '*.4

'(* '*.4

'1( '*.4

'* '*.4

'4( '*.4

Time/sec0 p#

* .('

'( '*.4

)* '*.42

3( '*.43

1* '*.42

5( '*.4(

4* '*.43

'*( '*.43

'2* '*.4(

')( '*.43

'(* '*.4(

'1( '*.4(

'* '*.4(

'4( '*.4(

2'* '*.4(

22( '*.4(

Time/sec0 p#

* .(

'( '*.5

)* '*.54

3( '*.4)

1* '*.4)

5( '*.4)

4* '*.4(

'*( '*.4(

'2* '*.4(

')( '*.4(

'(* '*.41

'1( '*.41

'* '*.41

'4( '*.41

2'* '*.41

22( '*.41

200 Rpm and 2.2 cm bafe with 5cm turbine size

* (* '** '(* 2** 2(*

.(

4

4.(

'*

'*.(

''

''.(

Time (sec)

pH

200 Rpm and 2.2 cm bafe with 6cm turbine size


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* (* '** '(* 2** 2(*

.(

4

4.(

'*

'*.(

''

''.(

Time (sec)

pH

200 Rpm and 2.2 cm bafe size with 7cm turbine size

* (* '** '(* 2** 2(*

.(

4

4.(

'*

'*.(

''

''.(

Time (sec)

pH

Time/sec0

6. turbine/cm0

'*( (

'(* 1

'(* 5


4/5

5( 4( ''( ')( '(( '5(

3

(

1

5

Time (sec)

O T!"i$e (cm)

RESU%T

The optimum turbine size is found to ( cm.

DISCUSSION$gitation is means whereby mixing phases can be accomplished and by

which mass and heat

transfer can be enhanced between phases or external surfaces. The operation of

agitation, which includes mixing as a special case, is now well established as an

important and in a wide variety of chemical processes.

&peci7cally, agitators are applied to three general classes of problems8

To produce static or dynamic uniformity in multi component multiphase

systems.

To facilitate mass or energy transfer between the parts of a system not ine%uilibrium.

To promote phase changes in multi component system with or without a

change in compositions.

Mixing in tan!s is an important area when one considers the number of

processes, which are accomplished in tan!s. 9ssentially, any physical or

transport process can occur during mixing in tan!s. :ualitative and %uantitative

observations, experimental data, and ;ow regime identi7cations are needed and

should be emphasized in any experimental pilot studies in mixing. $ vortex is

produced owing to centrifugal force acting on the rotating li%uid. f vortex

reaches the impeller severe air entrainment occurs. The depth and the shape ofthe vortex depend on impeller and vessel dimensions as well as on rotational

speed.

Mixing e


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the shaft. n ba"ed tan!s, a better concentration distribution throughout the

tan! and therefore improvement in the mixing ePM. Turbine should be operating below critical speed

which is speed at which both fre%uencies of turbine /vibration and rotational0reinforce one another.

n our experiment it is observed that for same ba"e size, the e

exp 5 baffle turbine

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