university of jordan faculty of engineering and technology

University of Jordan

Faculty of Engineering and Technology

Department of Chemical Engineering

Chemical Engineering Laboratory (3)

1

Experiment Number -1-

Gas absorption

Objectives

1. To study the hydrodynamic characteristics of a packed column.

2. To establish a mass balance on the absorbed gas in the column.

3. To determine mass transfer coefficients, the number of transfer units and the effective height

equivalent to a transfer unit.

Apparatus

The equipment consists of a packed column of 2 meters in height and 7.5 cm in diameter, packed

with 10mm glass Raschig rings. Air compressor is supplied with a flow meter. Carbon Dioxide

cylinder is also available with a flow meter. Water supply tank is available with water pump, and a

flow meter to indicate the flow of water. Mercury manometer and water manometer present to

indicate the pressure drop across the column.

Procedure

1. Fill the water supply tank with water.

2. Make sure that valves V1, V2, and V7 are closed and that V4 and V5 are open.

3. Check that the manometers show zero pressure difference across the column.

4. Switch on air compressor. Adjust valve V2 and take readings of manometers at different

values of air flow rates.

5. Repeat again with packed column in wet.

6. Repeat again with different values of water flow rates.

7. To determine mass transfer coefficient, adjust flow rates of water and air so that the

condition in the absorption column between flooding point and loading point.

8. Allow Carbon Dioxide to enter the column at certain flow rate.

9. At steady state, take a sample of the liquid going to drain and find the concentration of

Carbon Dioxide in it by titrating against NaOH solution.

2

Theory

When a liquid is flowing counter currently to the gas, for low gas flow rates, the effect is as for

the wet packing:

The pressure drop increases, and the pressure drop follows a square law characteristics.

Further increase in gas flow rate or liquid flow rate makes the liquid fails to drain from some sections

of the tower.

Pressure drop for dry packing (kg.m-2

) is given by:

𝛥𝑃𝑑 =𝐶. 𝑔𝑜

2

𝜌𝑔

Where:

𝑔𝑜= mass velocity of the gas based on the total cross section of the tower (kg.m-2

.s-1

)

𝜌𝑔= gas density (kg.m-3

)

C= constant which equals to 264 for 10 mm Raschig rings.

Pressure drop for wetted packing (kg.m-2

) is given by:

∆𝑃 = 𝛥𝑃𝑑 . 𝐴𝑙

𝑙𝑜𝑔𝐴𝑙 =𝐵. 𝑔𝑙

𝜌𝑙

Where: 𝑔𝑙= liquid flow rate based on the total cross section of the tower (kg.m-2

.s-1

)

𝜌𝑙= liquid density (kg.m-3

)

B= constant which equals to 0.084 for 10 mm Raschig rings.

For mass transfer characteristic

Consider a packed tower of cross section sectional area A; assume that the effective

interfacial area for mass transfer of liquid film on the packing is a ( 𝑚2

𝑚3 ) of the tower volume.

The area for mass transfer in small increment of height dh will be a(A.dh) m2, and the quantity

of solute in the gas passing into solution in this incremental height is d(Gy).

If Kog is the overall mass transfer coefficient based on the gas phase, then:

𝑑 𝐺𝑦 = 𝐾𝑜𝑔 . 𝑎. 𝐴. 𝑦∗ − 𝑦 .𝑑ℎ

3

𝐻 = 𝑑(𝐺𝑦)

𝐾𝑜𝑔 . 𝑎. 𝐴. 𝑦∗ − 𝑦

𝑦1

𝑦2

The height of transfer unit 𝐻𝑜𝑔 is

𝐻𝑜𝑔 =𝐺

𝐾𝑜𝑔 .𝑎. 𝐴

The number of transfer unit 𝑁𝑜𝑔 is

𝑁𝑜𝑔 = 𝑑𝑦

𝑦∗ − 𝑦

𝑦𝑡

𝑦𝑏

And H=𝑁𝑜𝑔 . 𝐻𝑜𝑔

Similarly, in terms of the liquid phase;

H=𝑁𝑜𝑙 . 𝐻𝑜𝑙

Calculations

1-Draw the hydrodynamic characteristic curves of the packed column and find the loading point and

the flooding point.

2-Establish a total mass balance on Carbon Dioxide and discuss the difference between the inlet and

outlet Carbon Dioxide amounts.

3-Calculate the overall mass transfer coefficient, the number of transfer unit, and the height of

transfer unit.

4

References

1- J. M. Coulson, and J. L. Richardson, “Chemical Engineering” vol.2, Pergamon Press.

2- Treybal, R. E; “Mass Transfer Operations”, McGraw Hill.

3- Foust, A.S; Wenzel, L.A; Clump, C. W; Mans, L; and Anderson, L.B; Principles of Unit

Operations”, Wiley-Mass Transfer, chapter 14, 16.

4- Nrman, A.S; “Absorption, Distillation and Cooling Towers‟‟, Longman, London-1962.

5

Gas Absorption

Raw Data Sheet part (1)

Dry Packing Wet Packing Water flow Rate= Water flow Rate= Water flow Rate=

Air flow

rate ∆P

Air flow

rate ∆P

Air flow

rate ∆P

Air flow

rate ∆P

Air flow

rate ∆P

6

Raw Data Sheet part (2)

Run No. 1 2 3 4 5

Inlet Water Flow Rate

(ml/min)

Inlet Air Flow Rate

(ml/min)

Inlet Carbon Dioxide Flow

Rate(ml/min)

Concentration of NaOH

solution(mol/l)

Volume of sample(ml)

Volume of NaOH titrant

(ml)

Temperature of outlet

solution (ºC)

Instructor’s Signature:

Date:

7


Distillation

Objectives

1- To demonstrate the effect of variation of reflux ratio upon distillate composition.

2- To determine the number of theoretical plates within the column using the methods of

McCabe and Thiele and Panchon and Savarit.

3- To find the Murphee plate efficiency.

Apparatus

Distillation unit is a semi-pilot plant comprises a reboilet operating on steam. Process vapors

enters at the base of either 80 mm packed column; packed with 10 mm glass Raschig rings, or 80 mm

bubble cap column contains 8 bubble-cap plates. At the top of each column there is an overhead

condenser.

Just below the overhead condenser, there is a liquid distillate separator that leads to reflux

control flow meters; RI.1A and RI.1B, RI.1A indicates the quantity of distillate returned to either column,

while RI.1B indicates the quantity of distillate removed as product.

Product distillate is cooled in the product cooler and passes through a measuring cylinder and

can be either collected in a vessel or returned to the reboiler.

Cooling water is available from the main cooling tower and pumped to the condensers through

the flow-meter FI.2. Temperature indicators are available for measuring temperature of liquid and vapor

along either column.

Procedure

1- Put 20 ml liters of water and methanol (5:1) in the feed vessel.

2- Start the cooling water pump and slowly adjust the flow rate of cooling water using valve

FCV2 to about 4 L/min on flow meter F12. Note that the pressure on PI2 should not

exceed 2 bars. In case no visual indications of water flow, close FCV2 and ask your

supervisor.

3- Making sure that V6 is closed, open V12 and close V13 or vice versa depending on the

column to be operated upon.

4- Open slowly PCV4 to let steam in and also open V11 (steam trap by-pass). Once steady

flow of steam issues from the drain, close V11. Note that the pressure of steam should not

exceed 1.5 bar.

5- When distillate liquid is seen on top of the column, open valve PCV1 to allow flow

through flow meter RI.1B.

8

6- With the aid of measuring cylinder RI.1C and stop watch, flow rate through RI.1B should

be calibrated.

7- Once the calibration is done, adjust flow rate through flow meters RI.1b to give the

desired reflux ratio.

8- Take the temperature readings across the column as well as a sample from the liquid

distillate. Find the refractive index of the sample.

9- The experiment should be repeated at different reflux ratio.

10- Repeat for the other column.

Theory

The distillation column available in the laboratory is an enriching section of a distillation

column. The relationship between vapor (y) and liquid (x) as they pass each other between

theoretical plates is given by (Numbering of plates increase from top to bottom).

𝑦𝑛=1 = 𝑅

𝑅 + 1 𝑋𝑛 +

𝑋𝐷

𝑅 + 1

Where:

R= Reflux ratio

XD = composition of distillate at the top of the column.

That is the equation of the operating line for McCabe and Thiele method, and passes the points

(y1, XD) and has an intercept of 𝑋𝐷

𝑅+1 .

For Ponchon and Savarit method, the operating line is given by 𝐿𝑛

𝐷=

𝑋𝐷−𝑦𝑛+1

𝑦𝑛+1−𝑋𝑛=

𝑄 ′−𝐻𝑉𝑛+1

𝐻𝑉𝑛+1−𝐻𝐿𝑛

Where:

D= Distillate rate.

HVn+1 = Enthalpy of liquid at its dew point.

H Ln = Enthalpy of liquid at its boiling point.

𝑄′ =𝑄𝑐 + 𝐷𝐻𝐷

𝐷

Where:

9

Q = heat removed in the condenser.

The above equation is the equation of a straight line passes through the points (HVn+1 ,y n+1) and (H Ln , Xn )

and ( 𝑄′ , XD ) at ∆D (difference point).

Murphee plate efficiency in vapor terms is given by

𝐸𝑚𝑉 =𝑦𝑛 − 𝑦𝑛+1

𝑦𝑒 − 𝑦𝑛+1

And in liquid terms:

𝐸𝑚𝐿 = 𝑋𝑛−1 − 𝑋𝑛

𝑋𝑛−1 − 𝑋𝑒

Calculations

1- Graphically show the relationship between the rotameter scale readings RI.1B and the

actual flow rate.

2- Calculate the number of theoretical plates using the methods of McCabe and Thiele and

Ponchon and Savarit for bubble cap column for one reflux ratio only.

3- Graphically show the relationship between reflux ratio and the top composition for both

column and compare between the results.

4- Find Murphee plate efficiency.

10

Equilibrium data for Methanol- Water system @ P= 681 mmHg.

TEMPERATURE x1 (methanol) y1 (methanol)

°C mol/mol mol/mol

97.0596 0 0

95.4691 0.01 0.0755924

93.7949 0.02 0.139381

92.293 0.03 0.193918

90.9367 0.04 0.241082

88.5793 0.06 0.318613

86.5944 0.08 0.379801

84.8944 0.1 0.42947

81.5234 0.15 0.521318

78.9814 0.2 0.585619

76.9566 0.25 0.634452

75.2727 0.3 0.673881

73.8227 0.35 0.707274

72.538 0.4 0.736645

71.3732 0.45 0.763266

70.2974 0.5 0.787979

69.2886 0.55 0.811353

68.3317 0.6 0.833787

67.4154 0.65 0.855558

66.532 0.7 0.876864

65.6757 0.75 0.897837

64.8425 0.8 0.918569

64.0296 0.85 0.939118

63.2349 0.9 0.959519

62.9217 0.92 0.967645

62.6112 0.94 0.975754

62.303 0.96 0.983847

62.1499 0.97 0.987889

61.9973 0.98 0.991928

61.8453 0.99 0.995965

61.5566 1 1

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11

Enthalpy Data for Methanol-Water mixture

HL( J/g.mole) X Y HV( J/g.mole)

6061 0 0 47652

5267 0.05 0.273 45144

4723 0.1 0.418 43681

4389 0.15 0.517 42678

4138 0.2 0.579 42009

3929 0.3 0.665 41089

3846 0.4 0.729 40379

3804 0.5 0.779 39835

3804 0.6 0.825 39334

3804 0.7 0.87 38832

3804 0.8 0.915 38331

3816 0.9 0.958 37871

3887 0.95 0.979 37620

3954 1 1 37453

12

Distillation

Raw Data Sheet

Run # RI.1A RI.1B T3 T2D T2C T2F T2E TI.1

1

2

3

4

5


Date:

13


Water Cooling Tower

Objective

To study the mass transfer characteristics of a packed water cooling tower.

Apparatus

A forced draught laboratory packed tower is used. The tower is mounted in the Chemical

Engineering main laboratory, pilot plants area. The total depth of packing (z) is 1.27m. Dry and

wet bulb temperatures of all streams could be measured by mercury thermometers located at

different point in the column. Air flow rate can be measured by an orifice meter. Water flow rate

is measured by a flow meter.

Calculations

1.For each run, calculate the overall mass transfer coefficient ky.a using the relation:

Z=HtOG . NtOG

Z = total depth of packing=1.27m

HtOG = height of transfer unit. (m)

NtOG = number of transfer unit .

HtOG=aky

Gs

.

Gs= mass flow rate of inert gas. (Kg/hr)

NtOG=

2

1

*

H

HHH

dH== area under the curve of (1/(H

*-H) vs. H)

H =Enthalpy of air at wet and dry temperatures. (KJ/kg)

H*=Enthalpy of air at equilibrium. (KJ/kg)

14

The integral is to be evaluated using a graphical integration method.

2. The values of ky.a at different gas and liquid flow rates are correlated by the relation:

Ky.a= )(

L

Gs

, = constants

References

1-Treybal; R.E., „Mass Transfer Operations‟, McGraw Hill.

2-J.M.Coulson, and J.L. Richardson, “Chemical Engineering”, vol. 1, Pergamon press.

15

Water Cooling Tower

Raw Data Sheet


Date:

Run No. 1 2 3 4 5

Inlet water Flow

Rate(kg/hr)

Inlet air Flow Rate

(m3/hr)

Inlet air dry bulb

temperature (ºC)

Inlet air wet bulb

temperature (ºC)

Outlet air dry bulb

temperature (ºC)

Outlet air wet bulb

temperature (ºC)

Inlet water

temperature (ºC)

Outlet water

temperature (ºC)

16


Liquid-Liquid Extraction

Objectives:

To examine the mass transfer coefficient‟s dependence on liquid flow rate for counter current

liquid-liquid extraction in a packed column.

Procedure:

1. Prepare approximately 20 liters of 0.5 N solution of benzoic acid in toluene and place in

feed tank.

2. Fill water storage tank with approximately 20 liters of distilled water.

3. Start water pump and set water flow rate to 200ml/min.

4. Once the extraction column is filled with water, start the feed tank pump.

5. Keep the interface between the organic and aqueous phases constant so that steady state

could be achieved.

6. Operate for thirty minutes and then take a sample of each outlet stream and toluene-

benzoic acid inlet stream.

7. Titrate the aqueous phase sample with 0.05 M sodium hydroxide solution and the organic

phase samples with 0.20 M ethanolic sodium hydroxide solution.

8. Repeat sampling after 5 minutes and the run to be stopped if two successive readings are

the same.

9. Repeat for different flow rates of water.

Calculations:

Calculate the mass transfer coefficient and find its dependence on liquid flow rate.

References:

1. J. M. Coulson, and J. L. Richardson, “Chemical Engineering” vol. 2, Pergamon Press.

2. Treybal, R. E., “Mass transfer Operations”, McGraw Hill.

3. T. J. Appel and J. C. Elgin, Counter Current Extraction of Benzoic Acid between

Water and Toluene, Ind. Eng. Chem. Vol. 29, No. 4, pg 451-459.

17

Liquid-Liquid Extraction

Data Sheet

Concentration of aqueous NaOH: …………………………..

Concentration of ethanolic NaOH: …………………………

Run No. 1 2 3 4 5

Water flow rate

Volume of ethanolic

NaOH titrant needed

for feed solution

Volume of ethanolic

NaOH titrant needed

for Raffinate

Volume of aqueous

NaOH titrant


Date:

y = -0.016x2+ 0.876x + 1.463

0

2

4

6

8

10

12

14

0 5 10 15 20 25

Co

nce

ntr

atio

n o

f B

ezo

ic a

cid

-aq

uo

es

ph

ase

(Ib

mo

l/ft

3)*

10

-4

Concentration of Benzoic acid-organic phase (Ibmol/ft3)*10-3

19


Determination of Diffusion Coefficient

Objectives:

1. To determine the diffusion coefficient of acetone vapor into a stagnant non-diffusion air film.

2. To determine the convective mass transfer coefficient kc of the evaporation of pure Acetone into air

film.

Introduction:

The diffusivity or diffusion coefficient D depends upon the temperature, pressure and the nature of

the components of the system. When a stream of air is blown across the top of the tube at a sufficient

rate, evaporation of pure liquid Acetone at the bottom of the narrow tube will take place and the liquid

boundary will move with time .If the length of the diffusion path changes a small amount over a long

period of the time the pseudo-steady state diffusion model may be used to calculate the diffusion

coefficient of Acetone into air.

Procedure:

1. Fill the narrow tube with Acetone to within 20mm of top of the tube. 2. Immerse the cell in the constant temperature water bath which is maintained at 30⁰C. 3. Measure the length of the initial diffusion path (Z0) using the vernier caliber. 4. Connect the air tube to the air source and open the air valve. 5. Measure the length of the diffusion path after 90 min and after 180 min.

Air

Z

Aceton

e

20

Determination of Diffusion Coefficient

Raw Data Sheet

Temperature: ____________________

Density of Acetone: _____________________

Atmospheric Pressure: __________________

Time Height


Date:

21


Wetted Wall column

Objectives

1. To measure the Sherwood number for mass transfer from the wall into turbulent air flow

for different liquids with varied air flow rates.

2. To Correlate the result in the form: 6.0Re cb Scash ; and find a, b, and c.

3. To Compare the experimental results with the various available analogies between

momentum , heat and mass transfer e.g. Reynolds Analogy, Van Karman Analogy ,

Colburn – Chilton Analogy and Sherwood Gilliland correlation.(See ref. (1) and (3) ).

Equipment

The wetted wall column consists mainly of a vertical pipe of known diameter and length.

Liquid flows down the inside wall of the column and air is blown counter currently up the

column. Heaters are provided for both the air and the liquid. Air and liquid rates are measured by

flow meter. Air and liquid temperature are measured with thermometers.

The evaporation rate may be measured by observing the rate of change of liquid level in the

liquid reservoir.

Calculations

The mass transfer coefficient in the gas phase could be calculated from:

mg PAKNA

22

Where

NA mass transfer rate gm/s

Kg = mass transfer coefficient , gm/cm2

.s.atm.

A = area of gas- liquid interphace, cm2.

mP = logarithmic mean driving force difference, atm.

For Sh, Sc, and Re, see references.

References

1. R.E. Treybal , Mass Transfer Operation , 3 rd Ed.

McGraw – Hill Book Co.

2. W.L. Badger and J.T. Banchero , Introduction to Chemical engineering ,


3. O.C , Bennet and J.C Myero, Momentum Heat and Mass Transfer , 3 rd Ed.


23

Wetted Wall Column

Raw Data Sheet

Run No. 1 2 3 4 5

water Flow Rate

Air Flow Rate

Inlet water

temperature (ºC)

Outlet water

temperature (ºC)

Inlet air dry bulb

temperature (ºC)

Inlet air wet bulb

temperature (ºC)

Outlet air dry bulb

temperature (ºC)

Outlet air wet bulb

temperature (ºC)


Date:

24


Adsorption of Dye Solution on Activated Carbon

Objectives:

1. To produce Concentration –Time curve for the adsorption of dye solution by activated

carbon.

2. To investigate the effect of initial dye concentration and speed of agitation on the

Concentration- Time curves.

3. To construct the equilibrium isotherm for the adsorption of solute on adsorbent.

Introduction:

Activated carbon adsorption is one of the physical purification techniques which offer one of

the most efficient processes available for removing certain organics and in-organics from waste

water.

Physical adsorption results from the action of Vander Waals forces comprised of London

dispersion forces and classical electro-static forces between adsorbate and adsorbent.

Apparatus:

The apparatus comprises of 3×2 L beakers, 3 variable motors, 50 small bottles (about 10-15 ml),

and visible spectrophotometer.

Materials:

Activated carbon and dye solutions

25

Procedure:

a) Isotherms 1. Make up 2 liters dye solution by dissolving exactly 1g dye in 2 liters of

distilled water.

2. Using the small bottles, weigh out 0.001, 0.002, 0.004, 0.008, 0.012, 0.016,

0.020, 0.030, 0.040, 0.080, 0.100,and 0.15 (g carbon).

b) Batch studies 1. Fill the beaker to 1.7 liter of dye solution; adjust the speed of agitator to three

different values in the beakers (100,200,300rpm).

2. Add .085 g of carbon to each beaker. Time sample should be taken for the

three beakers after (1, 2, 3,4, 6, 9, 15, 25, 35, 49, 64, and80 min).

3. Repeat step 1 and 2, but change the amount of carbon to 1.2g.

Calculations:

1. Plot (Cf/C0) vs. time for the three different speeds.

2. Plot the equilibrium isotherm curve and find the Freunlich equation constants

References:

1. Treybal, R.E, “Mass Transfer Operation”, McGraw Hill.

2. Perry and Chilton, “Chemical Engineer‟s Handbook” ,McGraw Hill.

26

Adsorption of Dye Solution on activated Carbon

Raw Data Sheet (1)

a. Isotherms

Volume of Solution

Initial Concentration of Solution

Mass of Carbon (g) Reading of (Absorbance OR

Transmittance) at equilibrium

0.001

0.002

0.004

0.008

0.012

0.016

0.020

0.030

0.040

0.080

0.100

0.150

27

Raw Data Sheet (2)

b. Batch Studies

Run Number: ______1_______

Volume of the Solution

Mass of Carbon

Speed of Agitator


Time Reading of (Absorbance OR Transmittance)

1

2

3

4

6

9

15

25

35

49

64

80

28

Run Number: _____2________


Mass of Carbon

Speed of Agitator



1

2

3

4

6

9

15

25

35

49

64

80

29

Run Number: ____3_________


Mass of Carbon

Speed of Agitator



1

2

3

4

6

9

15

25

35

49

64

80

30

Run Number: ____4_________


Mass of Carbon

Speed of Agitator



1

2

3

4

6

9

15

25

35

49

64

80


Date:

31

0

5

10

15

20

25

0 10 20 30 40 50 60 70 80 90 100

Co

nce

ntr

atio

n(p

pm

))

Trasmittance(%)

32

0

10

20

30

40

50

60

70

80

90

100

-0.01 0.01 0.03 0.05 0.07 0.09 0.11 0.13 0.15

(Tra

nsm

itta

nce

)

Mass (g)

Isotherm

33


Soxhlet Extraction

Objectives:

- To study Solid-Liquid extraction process using Soxhlet extractor.

- To investigate the effect of residence time and solvent type on the extraction of oil

from Olive cake.

- To calculate the Soxhlet extraction efficiency.

Equipment:

The experiment apparatus (Figure (1)) consists of:

Soxhlet extractor - 40 mm ID, with 500-mL round bottom flask.

Thimble

Condenser

Heating mantel

Figure (1): A schematic diagram of a Soxhlet extractor

1. Solvent

2. Still pot

3. Distillation arm

4. Thimble

5. Solid

6. Siphon top

7. Siphon exit

8. Expansion adapter

34

The solid material containing some of the desired compound is placed inside a thimble made

from thick filter paper, which is loaded into the main chamber of the Soxhlet extractor. The

extraction solvent to be used is taken into a distillation flask and the Soxhlet extractor is then

equipped as shown in fig (1).

The solvent is heated to reflux. The solvent vapor travels up the distillation arm and floods into

the chamber housing the thimble of solid. The condenser ensures that any solvent vapor cools,

and drips back down into the chamber housing the solid material.

The chamber containing the solid material is slowly filled with warm solvent. Some of the

desired compound will then dissolve in the warm solvent. When the Soxhlet chamber is almost

full, the chamber is automatically emptied by a siphon side arm, with the solvent running back

down to the distillation flask. This cycle may be allowed to repeat many times, over hours or

days.

After extraction the solvent is removed, typically by means of a rotary evaporator, yielding the

extracted compound.

Theory:

Solid liquid extraction (leaching) means the removal of a constituent from a mixture of solids by

bringing the solid material into contact with a liquid solvent that dissolves this particular

constituent. In this experiment oil is extracted from olive cake.

The amount of oil extracted (oil percentage) can be calculated as follow:

𝐎𝐢𝐥 𝐩𝐞𝐫𝐜𝐞𝐧𝐭𝐚𝐠𝐞 = 𝐖𝐞𝐢𝐠𝐡𝐭 𝐨𝐟 𝐬𝐨𝐥𝐢𝐝 𝐛𝐞𝐟𝐨𝐫𝐞 𝐞𝐱𝐭𝐫𝐚𝐜𝐭𝐢𝐨𝐧 − 𝐖𝐞𝐢𝐠𝐡𝐭 𝐨𝐟 𝐬𝐨𝐥𝐢𝐝 𝐚𝐟𝐭𝐞𝐫 𝐞𝐱𝐭𝐫𝐚𝐜𝐭𝐢𝐨𝐧

𝐖𝐞𝐢𝐠𝐡𝐭 𝐨𝐟 𝐬𝐨𝐥𝐢𝐝 𝐛𝐞𝐟𝐨𝐫𝐞 𝐞∗ 𝟏𝟎𝟎%

𝐄𝐱𝐭𝐫𝐚𝐜𝐭𝐢𝐨𝐧 𝐄𝐟𝐟𝐢𝐜𝐢𝐞𝐧𝐜𝐲 =𝐄𝐱𝐩𝐞𝐫𝐢𝐦𝐞𝐧𝐭𝐚𝐥 𝐨𝐢𝐥 𝐩𝐞𝐫𝐜𝐞𝐧𝐭𝐚𝐠𝐞

𝐓𝐡𝐞𝐨𝐫𝐞𝐭𝐢𝐜𝐚𝐥 𝐨𝐢𝐥 𝐩𝐞𝐫𝐜𝐞𝐧𝐭𝐚𝐠𝐞 ∗ 𝟏𝟎𝟎%

Procedure:

Part 1: Residence Time effect

1. Weigh about 10 grams of olive cake sample.

2. Put the solid sample into a previously weighed thimble and then put into the Soxhlet

apparatus.

3. Add 100 ml of Hexane solvent to the extraction chamber.

http://en.wikipedia.org/wiki/Filter_paper

http://en.wikipedia.org/wiki/Solvent

http://en.wikipedia.org/wiki/Reflux

http://en.wikipedia.org/wiki/Distillation

http://en.wikipedia.org/wiki/Solvation

http://en.wikipedia.org/wiki/Siphon

http://en.wikipedia.org/wiki/Distillation

http://en.wikipedia.org/wiki/Rotary_evaporator

35

4. Turn the heat on and start the experiment.

5. End the experiment after 3 extraction cycles (3 siphons).

6. Turn off the heater and wait until it cools down. Remove the thimble and leave it in the

fume hood to dry out.

7. Repeat steps (1-6) three times doing 6, 9 and 12 cycles.

8. The next day, when the thimbles containing the olive cake are completely dry, record the

weight of each thimble.

Part 2: Solvent Type effect

1. Perform the experiment as in (Part 1) using (100 ml Hexane) and end it after 8 cycles.

2. Repeat the experiment using (100 ml Isopropanol) and end it after 8 cycles.

Note: Either Part 1 or Part 2 is done in the lab.

Calculations:

- Calculate oil percentage for each run.

- Draw the percentage of oil as a function of number of cycles done.

- Calculate the extraction efficiency.

- What are the optimum conditions (number of cycles and solvent type) for Soxhlet

extraction of oil from olive cake, why?

36

Soxhlet Extraction Data Sheet

Part 1: Residence Time effect

Type of

solvent

No. of

cycles

Thimble's

weight (g)

Olive cake

weight (g)

Final

weight (g)

Part 2: Solvent Type effect

Type of

solvent No. of cycles

Thimble's

weight (g)

Olive cake

weight (g)

Final

weight (g)


Date:

37


Tray Drier

Objectives:

1. To produce drying rate curve for a wet solid in air of fixed temperature and humidity.

2. To investigate the effect of air temperature, air velocity on drying rate.

3. To calculate the total heat transfer coefficient, and mass transfer coefficient for a wet solid in

air.

Equipment:

The apparatus comprises of an air duct mounted on a floor-standing frame. Air is drawn into

the duct by a motor whose speed can be controlled. The air passes over an electrically-heated

element into the central section of the duct where trays of the material to be dried are suspended

in the air stream. The trays are carried on a support frame which is attached to a digital balance

mounted above the duct.

Air is discharged to the atmosphere through an outlet duct section in which is mounted a

digital anemometer for measurement of air velocity. Wet and dry bulb temperatures of the air are

measured using an aspirated psychrometer.

Procedure:

1. Place one or more of the trays available with the experiment on the support frame inside the

air duct and record the weight.

2. Put some sand in one or more of the trays, and record the weight again.

3. Add some water to the sand and record the weight.

4. Switch on the unit and set the fan speed to the midpoint.

5. Switch on the heaters as well as the stop clock.

6. Record the weight of the wet sand + trays+ support frame together at regular time intervals as

well as the dry and wet bulb temperatures of air before and after the trays.

38

7. Record the velocity of air.

8. Once drying is complete, switch off the unit.

9. The procedure can be repeated with another variable such as air speed, or different material.

Theory:

Immediately after contact between the wet solid and drying medium (air), the solid

temperature adjusts until it reaches a steady state. The drying rate becomes constant and remains

constant until it reaches certain critical moisture content.

The constant rate of drying is given by:

cR = dryTh

- wetT .A

Rc =constant rate of drying (kg/hr)

h = heat transfer coefficient (KJ/hr.m2.k).

λ = latent heat of evaporation of water. (KJ/Kg)

Td,Tw = temperature of inlet dry &wet air.(K)

A = area of tray (m2)

The rate of drying (Rc) also depends upon the rate of diffusion of vapor into the bulk gas stream

and is given by:

cR = dh . .A ( w - )

hd = Mass transfer coefficient. (m/hr)

A =Area of tray/ trays. (m2)

ρ =Density of the gas. (kg/m3)

w = Humidity of the gas saturated with vapor at the inlet wet bulb temperature. (Kg/Kg)

= Humidity of the inlet gas .(Kg/Kg).

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Also amount of water evaporated (drying rate) can be given by:

.cR M A d ( 2 - 1)

M.Ad=V. ρ .Ad

V = air velocity. (m/hr)

Ad = cross-sectional area of duct. ( m2)

ρ = air density. (kg/m3)

2 , 1 = specific humidity of air at outlet and inlet of trays. .(Kg/Kg)

M = air mass flow rate per unit area (Kg/hr. ( m2)

Calculation:

1. Draw graph of moisture contents vs. time.

2. From the above curve, draw graph of drying rate vs. moisture contents and locate the critical

Points.

3. Calculate the mass transfer coefficient and heat transfer coefficient.

4. Perform a mass balance to get rate of drying and compare the results with the difference in

Weights.

40

Raw Data Sheet

Speed of Fan = ---------------------------- Scale Reading of Heater = --------------------

Mass of (holder + empty tray) = ---------------------------- Mass of (holder + empty tray+ dry solid) =------

Mass of (holder + empty tray+ wet solid) =------------------------

Time

(min)

Total

Mass

(g)

Inlet Air

Temperature

outlet Air

Temperature

Time

(min)

Total

Mass

(g)

Inlet Air Temperature outlet Air

Temperature

Dry

Bulb(ºC)

Wet

Bulb(ºC)

Dry

Bulb(ºC)

Wet

Bulb(ºC)

Dry

Bulb(ºC)

Wet

Bulb(ºC)

Dry

Bulb(ºC)

Wet

Bulb(ºC)

university of jordan faculty of engineering and technology

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