FACULTY OF CHEMICAL ENGINEERING

UniversitiTeknologi MARA (UiTM)

Sarawak JalanMeranek, Kampus Kota
Samarahan 1 94300 Kuching,
SARAWAK
Tel : +6082-677200 Fax: +6082-677300

TECHNICAL/EXECUTIVE
REPORT :
CHE246 SEPARATION
PROCESSES

Lab Title : GAS ABSORPTION

100
MARCH – JULY 2020 Date Performed : 21/4/20203
Group Group: EH1104A
member No. Name UiTM Student Signature
s No.
*Please cancel
which is not 1 Abel Xavier Kok 2018643882
necessary.

CRITERIA FULL MARKS MARKS

Part 1: Pre Lab
Presentation on 20
- background studies of the laboratory
work, objectives, methodology
expected findings from the work correctly stated
in own words. - Delivery skills
Part 2: Technical Report
Data/Result/Calculation
- Technical 20
- Non-technical 10
Discussion 25
Conclusion 10
Appendices/References 5
Timeliness 5
Organization & Appearance 5
TOTAL MARKS 100
Data/Results
/Calculation:

y
Density of Air, = 1.175 kg/m3

Density of Water, x = 996 kg/m3
Packing Factor, Fp = 900 m3
Column Diameter, D = 80 mm

Water Viscosity,
 x = 0.0008 kg/ms

DynamicVis cos ity ,  x

Kinematic Viscosity of Water, Vx =
DensityOfW ater ,  x

0.0008kg / ms
3
V x = 996kg / m

V x = 0.8032 x 10-6 m2/s

D 2
Cross Sectional Area, AC = 4

 (0.08m) 2
AC = 4

AC = 0.0050 m2

Liquid Mass Velocity, Gx

 (WaterFlowR ate, Qx )( DensityOfW ater ,  x )
Liquid Mass Velocity, Gx =
CrossSecti onalArea , Ac

For 1.0 L/min,

(1.6667 x10 5 m 3 / s )(996kg / m3 )
Gx = (0.0050m 2 )

Gx = 3.3201 kg/s.m2

For 1.5 L/min,

(2.5 x10 5 m 3 / s )(996kg / m 3 )
Gx = (0.0050m 2 )

Gx = 4.98 kg/s.m2

Water Flow Rate, Qx Gx, kg/s.m2

(L/min) (m3/s)
1.0 1.6667 x 10-5 3.3201 kg/s.m2
1.5 2.5 x 10-5 4.98 kg/s.m2

Gas Mass Velocity, Gy

( AirFlowRate, Q y )( DensityOfA ir ,  y )

Gas Mass Velocity, Gy =

CrossSecti onalArea , Ac

For 40 L/min,
(6.6667 x10 4 m 3 / s )(1.175kg / m 3 )
Gy = 0.0050m 2

Gy = 0.1567 kg/s.m2

For 60 L/min,
(1x10 3 m3 / s)(1.175kg / m 3 )
Gy = 0.0050m 2

Gy = 0.2350 kg/s.m2

For 80 L/min
(1.3333x10 3 m 3 / s )(1.175kg / m3 )
Gy = 0.0050m 2

Gy = 0.3133 kg/s.m2

For 100 L/min,

(1.6667 x10 3 m3 / s )(1.175kg / m 3 )
Gy = 0.0050m 2

Gy = 0.3917 kg/s.m2
 For 120 L/min,
(2 x10 3 m 3 / s )(1.175kg / m 3 )
Gy = 0.0050m 2

Gy = 0.4700 kg/s.m2

Air Flow Rate, Qy Gy, kg/s.m2

(L/min) (m3/s)
40 6.6667 x 10-4 0.1567 kg/s.m2
60 1.0000 x 10-3 0.2350 kg/s.m2
80 1.3333 x 10-3 0.3133 kg/s.m2
100 1.6667 x 10-3 0.3917 kg/s.m2
120 2.0000 x 10-3 0.4700 kg/s.m2

Capacity Parameter, y-axis

13.1(G y ) 2 (Fp )(Vx ) 0.1

 y ( x   y )
Capacity Parameter, y-axis =

For 0.1567 kg/s.m2,

13.1(0.1567 kg / s.m 2 ) 2 (900m 3 )(0.8032 x10 6 m 2 / s) 0.1
y-axis = (1.175kg / m3 )(996kg / m 3  1.175kg / m 3 )

y-axis = 0.0609

For 0.2350 kg/s.m2,

13.1(0.2350kg / s.m 2 ) 2 (900m 3 )(0.8032 x10 6 m 2 / s) 0.1
y-axis = (1.175kg / m3 )(996kg / m 3  1.175kg / m 3 )

y-axis = 0.1369

For 0.3133 kg/s.m2,

13.1(0.3133kg / s.m 2 ) 2 (900m 3 )(0.8032 x10 6 m 2 / s ) 0.1
y-axis = (1.175kg / m 3 )(996kg / m3  1.175kg / m3 )

y-axis = 0.2433

For 0.3917kg/s.m2,
13.1(0.3917 kg / m.s 2 ) 2 (900m 3 )(0.8032 x10 6 m 2 / s) 0.1
y-axis = (1.175kg / m3 )(996kg / m 3  1.175kg / m 3 )

y-axis = 0.3803

For 0.4700kg/m.s2,
13.1(0.4700kg / s.m 2 ) 2 (900m 3 )(0.8032 x10 6 m 2 / s) 0.1
y-axis = (1.175kg / m3 )(996kg / m 3  1.175kg / m 3 )

y-axis = 0.5475
Flow Parameter, x-axis

Gx y
Gy x
Flow Parameter, x-axis =

For Gx = 3.3201 kg/s.m2, Gy = 0.1567 kg/s.m2,

3.3201kg / s.m 2 1.175kg / m 3
x-axis =
0.1567 kg / s.m 2 996kg / m 3

x-axis = 0.7277

For Gx = 3.3201 kg/s.m2, Gy = 0.2350 kg/s.m2,

3.3201kg / s.m 2 1.175kg / m 3

x-axis =
0.2350kg / s.m 2 996kg / m 3

x-axis = 0.4852

For Gx = 3.3201 kg/s.m2, Gy = 0.3133 kg/s.m2,

3.3201kg / s.m 2 1.175kg / m3

x-axis =
0.3133kg / s.m 2 996kg / m 3

x-axis = 0.3640

For Gx = 3.3201 kg/s.m2, Gy = 0.3197 kg/s.m2,

3.3201kg / s.m 2 1.175kg / m 3

x-axis =
0.3197 kg / s.m 2 996kg / m 3

x-axis = 0.2911

For Gx = 3.3201 kg/s.m2, Gy = 0.4700 kg/s.m2,

3.3201kg / s.m 2 1.175kg / m 3

x-axis =
0.4700kg / s.m 2 996kg / m 3

x-axis = 0.2426

For Gx = 4.98 kg/s.m2, Gy = 0.1567 kg/s.m2,

4.98kg / s.m 2 1.175kg / m 3

x-axis =
0.1567 kg / s.m 2 996kg / m 3

x-axis = 1.0916
For Gx = 4.98 kg/s.m2, Gy = 0.2350 kg/s.m2,

4.98kg / s.m 2 1.175kg / m 3

x-axis =
0.2350kg / s.m 2 996kg / m 3

x-axis = 0.7279

For Gx = 4.98 kg/s.m2, Gy = 0.3133 kg/s.m2,

4.98kg / s.m 2 1.175kg / m3

x-axis =
0.3133kg / s.m 2 996kg / m 3

x-axis = 0.5460

For Gx = 4.98 kg/s.m2, Gy = 0.3197 kg/s.m2,

4.98kg / s.m 2 1.175kg / m 3

x-axis =
0.3197 kg / s.m 2 996kg / m 3

x-axis = 0.4367

For Gx = 4.98 kg/s.m2, Gy = 0.4700 kg/s.m2,

4.98kg / s.m 2 1.175kg / m 3

x-axis =
0.4700kg / s.m 2 996kg / m 3

x-axis = 0.3639

Gx (kg/s.m2) x-axis
Air Flow Rate, Vy Gy y-axis
(L/min) (kg/s.m2) 1.0 L/min 1.5 L/min 1.0 L/min 1.5 L/min

40 0.1567 0.0609 0.7277 1.0916

60 0.2350 0.1369 0.4852 0.7279
80 0.3133 0.2433 3.3201 4.98 0.3640 0.5460
100 0.3197 0.3803 0.2911 0.4367
120 0.4700 0.5475 0.2426 0.3639
 Figure 1

Theoretical Pressure Drop

Flowrate (L/min) Theoretical Pressure Drop (mm H2O/m)

Air
40 60 80 100 120
Water
1.0 3.10 3.76 7.65 8.00 15.00
1.5 3.09 3.95 7.95 10.38 19.55

Log-Log Theoretical Pressure Drop

Flowrate (L/min) Theoretical Pressure Drop (mm H2O/m)

Air
1.6021 1.7782 1.9031 2.000 2.0792
Water
1.0 0.4914 0.5752 0.8837 0.9031 1.1761
1.5 0.4900 0.5966 0.9004 1.0162 1.2911
Experimental Pressure Drop

Flowrate (L/min) Pressure Drop (mbar)

air
40 60 80 100 120
water
1.0 212 247 261 500 564
1.5 325 341 530 575 677

( ExperimentalFlooding Po int, mBar) 10.197162129779mmH 2O

Conversion from mBar to mmH2O/m, 0.8m (1mBar)

Flowrate (L/min) Pressure Drop (mmH2O/mm)

air
40 60 80 100 120
water
1.0 2702.24 3148.37 3326.82 6373.23 7189.00
1.5 4142.59 4346.54 6755.62 7329.21 8629.35

Log-Log Experimental Pressure Drop

Flowrate (L/min) Pressure Drop (mmH2O/mm)

air
1.6021 1.7782 1.9031 2.000 2.0792
water
1.0 3.4317 3.4981 3.5220 3.8044 3.857
1.5 3.6173 3.6381 3.8300 3.8651 3.9360

 Theoretical Graph
 1.4

1.2

Pressure Drop (mm H2O/m)

1

0.8

0.6

0.4

0.2

0
1.5 1.6 1.7 1.8 1.9 2 2.1
Air Flow Rate (L/min)

1.0 L/min 1.5 L/min

Figure 2

 Experimental Graph

4
3.9
Pressure Drop (mmH2O/mm)

3.8
3.7
3.6
3.5
3.4
3.3
3.2
3.1
1.5 1.6 1.7 1.8 1.9 2 2.1
Air Flow Rate (L/min)

1.5 L/min 1.0 L/min

Figure 3

ExperimentalValue  Theoretica lValue

 100%
Percentage Error, % = Theoretica lValue

Flooding Point
Water Flow Rate Percentage Error
(L/min) Experimental Theoretical (%)
(mm H2O/mm) (mm H2O/mm)

1.0 3.857 1.1761 227.9483

1.5 3.9360 1.2911 204.8563
Discussion:

The main objective for the experiment is to examine the air pressure drop across the column as a function of air flowrate for
different water flowrates through the column. Air flowrates are adjusted from 40 L/min to 120 L/min. Data is collected when
flooding occurs. Based on Figure 3, the log pressure drop value increases as the log air flowrate value increases. This also indicates
that the air flowrates are proportional to the pressure drop value.

From the graph, we observe that, the higher the water flowrate, the lower the log air flowrate. This is due to the water
flowing downwards preventing the air flow upwards, resulting in the high pressure drop. Thus, at high water flowrates, flooding
happens faster than low water flowrates because the resistances of the water flowrates against the air flowrates are greater. The
same happens to the theoretical data, thuus proving that the experimental data shows the same pattern as the theoretical data.

4
3.9
Pressure Drop (mmH2O/mm)

3.8
3.7
3.6
3.5
3.4
3.3
3.2
3.1
1.5 1.6 1.7 1.8 1.9 2 2.1
Air Flow Rate (L/min)

1.5 L/min 1.0 L/min

Figure 3

For both theoretical and experimental data, the relationship between pressure drop value and air flowrates are proportional to
each other, the experimental pressure drop is larger compared to the theoretical pressure drop at water flowrates of 1.0 L/min and 1.5
L/min.

Both in theoretical and experimental data, the flooding occured at 120 L/min air flowrates for 1 L/min and 1.5 L/min water
flowrates. This results in an abysmal error for the experiment, which are 227.9483% and 204.8563% for 1.0 L/min and 1.5 L/min
water flowrates, respectively. The reason for this error is probably caused by human error. During the experiment, students need
to control the water from exceeding the entrance of the air flowrate at the bottom of the column. However, the water level at the
bottom could be too high, causing the air flowrate to be hindered, resulting in the late flooding flowrate. Another error that could
be taken into account is parallax error during the adjustment of flowrates. The student maybe did not read the measurement scale
at eye level where the eyes should be perpendicular to the measurement scale. For example, from 1.0 L/min to 1.5 L/min, the
student perhaps mistakenly adjusted at 1.4 L/min. Thus, affecting the flooding flowrate. However, the most logical explanation to
the abnormal percentage error obtained could be from the equipment itself. The equipment could have not been properly
maintained which resulted in different values at the measuring scale of the flowrate and the real flowrate within the packed tower.
 Besides, the theoretical data and the experimental data could vary due to the differences in packing tower such as the
packing in the tower. The packing degrade along with time, reducing the efficiency of the packings. Thus, also affecting the flooding
flowrates. To overcome these problems, measurements has been made to suit the flaws of the equipment to achieve our desired
results. Although error occurs, the experiment is still considered a success because we obtained a similar graph between the
theory and experimental graphs based on Figure 3.

Based on the experiment, we can observe that the packed tower used in the experiment is working efficiently at lower
water flowrate since flooding occurs at very high air flowrates. This allow contact time between the air and water to be lengthen,
thus maximizing the absorption rate. However, at high water flowrate, flooding was quick at low air flowrates. This shortened the
contact time between air and water to maximize absorption rate.

Conclusion:

The pressure drop increases as the air flowrate increases. The pressure drop also increases as the water
flowrates increases. The experimental pressure drop value for 1.0 L/min and 1.5 L/min water flowrate has shown to
significantly drop more than the theoretical pressure drop value. The percentage error is determined to be
227.9483% and 204.8563% for 1.0 L/min and 1.5 L/min water flowrates, respectively. Packing tower is proved to
work efficiently at low liquid flowrates compared to high liquid flow rates. Low liquid flowrates allows the
absorption rate to be maximized exponentially. With that, the experiment is deemed successful.
References:

Warren McCabe, Julian Smith and Peter Harriott (2004) Unit Operations of Chemical Engineering. 7th Edition, McGraw Hill.

Christi Geankoplis (2003) Transport Processes and Separation Process Principles, 4th Edition, Prentice Hall.

Christi Geankoplis (2003) Transport Processes and Separation Process Principles, 6th Edition, Prentice Hall.

Excellent (5 points Good (4 points each) Satisfactory (3 points each) Unsatisfactory (1-2
each) (7-8 points each) (4-6 points each) points each)
(9-10 points (14-17 points each) (8-13 points each) (1-3 points
each) (15-19 points each) (9-14 points each) each) (1-7
(18-20 points points each)
each) (1-8 points
(20-25 points each)
each)
Pre-Lab (20) ● Presentation on ● Presentation on ● Presentation Background ● Presentation
Background studies Background studies of the studies of the laboratory Background studies of
of the laboratory laboratory work, objectives, work, objectives, the laboratory work,
Score:
work, objectives, methodology and expected methodology and expected objectives,
methodology and findings from the work findings from the work methodology and
expected findings correctly stated but incorrectly stated in own expected findings are
from the work incomplete in own words. words. missing from the work,
correctly stated in ● Confident and good ● Confident and not a good incorrectly stated and
own words. presentation presentation not in own words.
● Very confident and ● Not confident and not
very good a good presentation
presentation

Data/Result/ ● Fully and correctly ● Fully and correctly use ● Inappropriate use the ● Inappropriate and
use the available the available data available data incorrectly use the
Calculation: (20)
data available data
Technical
● One incorrect graph or ● One incorrect graph or chart,
Score:
● Correct graphs, chart, or incorrect and incorrect calculations. ● More than one
charts, and calculations incorrect graph, chart,
calculations or calculation
 ● No missing or ● One or two missing or ● Few missing or incorrect ● Many missing or
incorrect units incorrect units units incorrect units
Data/Result/ ● Few significant figure
● No significant figure ● One or two significant ● Many significant figure
Calculation: (10) errors figure errors errors errors
Non-Technical ● Graphs completely ● Few missing or incorrect ● Many missing or
● One or two missing or
and correctly labeled labels on graphs incorrect labels on
incorrect labels on graphs
(title & axis) ● Captions on some figures, graphs
Score: ● Captions on most figures,
● Captions on all tables, graphs, charts, ● Captions on little or no
tables, graphs, charts, etc.
figures, tables, etc. figures, graphs, charts,
● Correct but insufficient
graphs, charts, etc. ● Incorrect but sufficient etc. ● No equations
shown
● Correct and equations shown
sufficient equations shown
shown
Discussion (25) ● Demonstrated a ● Demonstrated an ● Demonstrated some ● Demonstrated little or
thorough adequate understanding understanding and no understanding and
understanding and and comprehension of comprehension of the comprehension of the
Score:
comprehension of the results results results
the
results
● Analysis and ● Analysis and results ● Analysis and results correctly ● Analysis and
results correctly incorrectly but but inadequately compared results incorrectly
Conclusions (10)
and adequately adequately compared to theory, equations, and and inadequately
compared to to theory, equations, practical applications. compared to
Score: theory, and practical theory, equations,
equations, and applications. and practical
practical applications.
applications.
Use of ● Information is ● Selection and/or extent ● Content in appendix is not ● Appendices were not
placed of material in appendix complete. utilized when
Appendices
appropriately may not be optimal. ● On several instances, appropriate.
&/or References in the main ● With an occasional references are not stated ● Little attempt is
(5) text or an oversight, prior work is when appropriate. made to
Score: appendix. acknowledged. acknowledge the
● Reference to work of others.
sources for ● Inaccurate/unclear
theories, references.
assumptions,
quotations, or
findings.
Timeliness (5) - -
Score: In time Late
Organization & ● The document is ● The document is ● Within sections, the order ● There is no apparent
easily navigated organized. in which ideas are ordering of
Appearance (5) ● Information is not in the
(assisted by presented is occasionally paragraph, and thus
sectioning) appropriate section. confusing. there is no
Score: ● Information is in the ● The document is progressive flow of
appropriate section. somewhat appealing. ideas.
● The document is ● There are few “cues”
visually appealing. to help the reader
navigate the
document.
● The document is not
visually appealing.