elutriator. (1)

8/13/2019 Elutriator. (1)

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A

REPORT ON

WORKING OF AN ELUTRIATOR

Submitted to

Ms.Shabina Khanam

Associate Professor,

Department of Chemical Engineering

Indian Institute of Technology, Roorkee

Submitted by

Atiya Banerjee(M.Tech Ist yr,CAPPD)

Garima Vishal(M.Tech Ist yr,CAPPD)

Jyoti Tomar(M.Tech Ist yr,CAPPD)

Kuwar Singh(M.Tech Ist yr,ISHM)

Neelam(M.Tech Ist yr,CAPPD)

Vineet Kumar(M.Tech Ist yr,CAPPD)


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AIM:

To investigate the working of a standard elutriator and to analyze its separation abilities.

OBJECTIVE:

To determine the suitable water velocity for separating the giving solid mixture of the same

density on the basis of size.

THEORY:

An elutriator is a simple device which can separate particles into two or more groups. Material

may be separated by means of an elutriator, which consists of a vertical tube up which fluid is

passed at a controlled velocity. When the particles are introduced, often through a side tube,

the smaller particles are carried over in the fluid stream while the large particles settle against

the upward current. If one starts with low flow rates small less dense particle attain their

terminal velocities, and flow with the stream. The particle from the stream is collected in

overflow and hence will be separated from the feed. Flow rates can be increased to separate

higher size ranges. Further size fractions may be collected if the overflow from the first tube is

passed vertically upwards through a second tube of greater cross-section and any number of

such tubes can be arranged in series

Another use for elutriation can be seen in the analysis of mineral samples, as seen when

oceanographers want to research the composition of benthic clay or geologists want to

evaluate the contents of mineral deposits. Samples are separated by size and density in the

column, allowing people to generate a complete list of the materials present in the sample andto note their concentrations. People evaluating mineral deposits for commercial value are

particularly concerned with concentrations; a site may contain diamonds, for example, but in

such low amounts that they cannot be efficiently mined for sale.

The separation of solid particles into several fractions based upon their terminal velocities is

called classification. Suppose two particles having different settling velocities are placed in a

rising current of water; if the water velocity is adjusted to a value between the terminal

velocities of the two particles a separation will result. The slower settling particles will move

upward with the water while the faster settling particles simultaneously settle out at the bottom.

Thus if A and B are two different materials in a solid mixture with density of A more than thedensity of B, then if the size range of two materials is larger no complete separation is likely to

take place because the terminal velocity of the largest particle of B may be greater than that of

the smallest particle of A.


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APPARATUS:

The setup consists of three vertical tubes of different diameters in which water is passed at

controlled velocity. A tank with pump is provided for recycle water supply. Flow rate is

measured by Rotameter and controlled with the help of control valve and by-pass valve. The

tubes are arranged in a fashion of ascending cross-section. The particles are introduced

through a feed hopper provided at first tube; the smaller particles are carried over in the fluid

stream, while the larger particles settle against the upward stream. The over flow from the first

tube introduced the bottom of the second tube. The weighed sample originally placed in the

first tube of the smallest diameter is classified into fractions according to their settling

velocities. The fractions are collected in successive tubes by a special arrangement and

maybe dried and weighed to make analysis.

UTILITIES REQUIRED:

Electric supply single phase 220 VAC, 50 Hz 5-15 Amp socket with Earth connection. Water supply (Initial fill).

Drain required.

Floor area required 1.5 m X 1 m.

Raw material for the feed (Silica).

Oven for drying of product.

Electronic weighing balance (2kg least count .1 gm.).


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PROCEDURE:

Fix the flow rate of the Rotameter to its desired value and wait for 20 minutes.

Then take the sample and feed it (after weighing) through the hopper.

For a fixed flow rate calculate the velocity of water in different tubes of different

diameter.

Leave the whole set up for half an hour.

Then close the pump and again leave it for 1 hour so that particles settle down in

respective tubes of different diameter.

Open the stopper in order to collect the particles from tubes.

Then dry it in oven after filtration.

Weigh the particles and after sieving determine the range of diameter of particles

collected from each tube.


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OBSERVATION TABLE:

FIRST TUBE

ASTME

Mesh

Mesh

aperture Diameter(10^-6m) wt(gm) xi xi/dpi2 xi/dpi3

30 600 600 0 0 0 0

30-40 425 512.5 16.053 0.261833306 9.96867E-07 1.94511E-09

40-50 300 362.5 33.63 0.548523895 4.17426E-06 1.15152E-08

50-70 212 256 9.096 0.148360789 2.26381E-06 8.84299E-09

70-100 150 181 2.35 0.038329799 1.16998E-06 6.46399E-09

100-140 106 128 0.178 0.002903278 1.77202E-07 1.38439E-09

140-200 75 90.5 0.03 0.000489317 5.97438E-08 6.60153E-10

8.84186E-06 3.08118E-08

Cut diameter of the first tube = .08 m=286.9631622 m

Average arithmetic diameter (d) =

SECOND TUBE

ASTME

Mesh Mesh aperture Diameter(10^-6m) wt(gm) xi xi/dpi2 xi/dpi3

30 600 600 0.03 0.003134 8.70556E-09 1.45093E-

30-40 425 512.5 1.842 0.192456 7.3273E-07 1.42972E-

40-50 300 362.5 6.082 0.635461 4.83585E-06 1.33403E-

50-70 212 256 1.251 0.130707 1.99443E-06 7.79074E-

70-100 150 181 0.078 0.00815 2.48771E-07 1.37443E-

100-140 106 128 0.169 0.017658 1.07776E-06 8.41999E-

140-200 75 90.5 0.119 0.012433 1.51802E-06 1.67738E-

1.04163E-05 4.91434E-

Cut diameter of the second tube= 0.1 m=211.9565888 m


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THIRD TUBE

ASTME

Mesh Mesh aperture Diameter(10^-6m) wt(gm) xi xi/dpi2 xi/dpi3

30 600 600 0 0 0 0

30-40 425 512.5 0.015 0.001172 4.46211E-09 8.70655E-

40-50 300 362.5 0.02 0.001563 1.18944E-08 3.28122E-

50-70 212 256 0.752 0.058755 8.9653E-07 3.50207E-

70-100 150 181 6.152 0.480663 1.46718E-05 8.10597E-

100-140 106 128 4.815 0.376201 2.29615E-05 1.79387E-

140-200 75 90.5 1.045 0.081647 9.9688E-06 1.10153E-

4.8515E-05 3.74142E-

Cut diameter of the third tube = .15m= 129.6698213 m


V2=0.019696004 m/s V3=0.030744 m/s

D Ga 2/3Ga

log

2/3Ga log Re Re V A3 Q3 lpm

0.000107 19.36022489 12.90682 1.110819

-

0.02849 0.936505 0.008751 0.017668125 0.000154614 9.2768


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CALCULATING DIAMETER USING VELOCITY:

V f log f

ln Re

(from

table) Re D (m) D(m)

0.019696 1.378245932 0.139327 0.538 3.451437 0.000176 175.9166

0.030744 0.362378694 -0.44084 0.869 7.396053 0.000242 241.5009

RESULT:

The cut diameter for the different tubes is calculated by using Galileo number and considering cut diameter for the

last tube as 125 m. The calculations are performed using a constant flow rate

For first tube:

Cut diameter 241.5009 m

For second tube:

Cut diameter 175.9166 m

The velocity of fluid in all three tubes are calculated separately as follows from effective Reynolds

number by performing back calculation from Galileo Number and using results from log-log plot of

effective Reynolds number and drag coefficient parameter. Diameter of particle is used to calculate the

effective Reynolds number and interpolated to get the following results:

For first tube :

Velocity = 0.008751m/s

For second tube :

Velocity = 0.019696 m/s

For third tube :

Velocity = 0.030744 m/s


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DISCUSSION:

PRECAUTIONS:

Do not turn the pump at voltage less than180 and above 230 volts.

Never fullyclose the delivery line and By-pass valve simultaneously.

To prevent clogging of moving parts, run pumps at-least once in a fortnight.

After performing the experiment wait for half an hour so that particles settle down.

Always use clean water.


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