- The objective of the experiment was to examine the air pressure differential across a column as a function of air flow rate for different water flow rates down the column. - Pressure differential was plotted as a function of air flow rate on log-log graph paper for each water flow rate. - Results were calculated from measurements of differential height and plotted on log-log graphs, showing the relationship between air flow rate and differential pressure for different water flow rates.

1. King suad university
College of engineering
Chemical engineering department
Absorption
ChE403
Alawi Al-Awami 423101724
Meshal Al-Jahani 424105851
Meshal Al-Saeed 423105653
Date: 8/5/1429
Supervised :Dr. Malik Al-Ahmad
1

2.  Table of Contents :
Title Page
Summary 3
Introduction 4
Expierment objective 6
Theory 7
Schematic diagram 8
Experimental procedure 9
Results & Calculation 10
Discussion & Conclusion 16
Reference 17
2

3.  Summary :
 The objective of this experimental To examine the air pressure
differential across the column as a function of air flow rate
different water flow rates down the column.
 Pressure differential should be plotted as a function of air flow
rate on log-log graph paper for each water flow rate.
 From our experimental we read differential height and
calculated the differential pressure by using equation.
ΔP=ρ *g *Δh
 We calculated the results from table (1) to (6) and plotted log-log
graph between air flow rate VS. Differential pressure.
3

4.  Introduction :
Absorption is a mass transfer process in which a vapor solute A in a gas mixture
is absorbed by means of a liquid in which the solute more or less soluble. The gas
mixture consists mainly of an inert gas and the soluble. The liquid also is
primarily in the gas phase; that is, its vaporization into the gas phase is relatively
slight. A typical example is absorption of the solute ammonia from an air-ammonia
mixture by water. Subsequently, the solute is recovered from the
solution by distillation. In the reverse process desorption or stripping, the same
principle and equations hold.(1)
A major application of a absorption technology is the removal of CO2 and H2S
from nature gas or synthesis gas by absorption in solution of amines or alkaline
salts.(2)
A common apparatus used in gas absorption and certain other operations is the
packed tower, shown in Fig. (1) . The device consists of a cylindrical column, or
tower, equipped with a gas inlet an distributing space at the bottom; a liquid inlet
and distributor at the top; gas and liquid outlet at the top and bottom,
respectively; and a supported mass of inert solid shapes, called tower packing.(2)
Common dumped packing, Ceramic Berl saddles and Raschig rings are older
types of packing that are not much used now, although there were big
improvements over ceramic spheres or crushed stone when first introduced. The
shape prevent pieces from nesting closely together, and this increasing the bed
porosity.(2)
In given packed tower with a given type and size of packing and with defined
flow of liquid, there is an upper limit to the rate of gas flow, called the flooding
velocity. Above this gas velocity the tower cannot operate. At the flow rate called
the loading point, the gas start to hander the liquid downflow, and local
accumulations or pools of liquid start to appear in the packing.(1)
4

5. 5
FIG (1): PACKED TOWER FLOW AND CHARACSTERISTICS
FOR ABSORPSTION.

6.  Expierment objective
 To exmine the air pressure differential across the column
as a function of air flow rate for different water flow rate
down the column by Ploting the pressure differential as a
function of air flow rate on log-log graph paper and
establish the relationship between these variable.
6

7.  Theory:
 ΔP=ρ *g *Δh
Where:
ΔP: differential pressure. (g/cm.s2)
ρ: density. (g/cm3)
g: gravity constant. (cm/s2)
Δh: hight (cm H2O)
 Plot the pressure differential as a function of air flow rate
on log-log graph paper and establish the relationship
between these variable.
7

8.  SCHEMATIC DIAGRAM :( 3)
8

9. 
Experimenta l Procedure :
9
FIG (2): Gas absorption device.

10. 1- The first step we dried by passing the maximum air flow until all
evidence of moisture in the packing has disappeared.
2- We run on of the pump of air.
3- At zero flow of air we read the hight and recorded it
4- We increased flow air to 20(l/min) and read of hight a cross the
column.
5- We increased flow air to 40,60, 80,…,180(l/min) and read of hight then
recorded it for each one.
6- After that we changed flow of water to 1.5(l/min) and repeat step 3 to 5
after that changed flow water to 2, 2.5, and 3(l/min).
7- The range of possible air flow rates will decrease with increasing water
flow rate duo to onset of ‘flooding’ of column, which should be noted.
10

11.  Result & Calculation :.
dry colunm
air flow rate l /min 20 40 60 80 100 120 140 160
water flow rate l/min 0 0 0 0 0 0 0 0
Δp (cm H2O) 0.2 0.4 0.4 0.4 0.3 1.7 2.6 3.8
Δp (g/cm.s2) 196 392 392 392 294 1666 2548 3724
log air flow rate (l/min) 1.301029996 1.60206 1.778151 1.90309 2 2.079181 2.146128 2.20412
log Δp (g/cm.s2) 2.292256071 2.593286 2.593286 2.593286 2.468347 3.221675 3.406199 3.57101
Table (1): data of flow (air + water) and differential pressure at dried
column
dry c olunm
4
3.5
3
2.5
2
1.5
1
0.5
0
0 0.5 1 1.5 2 2.5
log Δp (g/cm.s2)
log air flow rate l /min
Figure (3): graph of log ΔP vs. log air flow.
11

12. .
wet column
air flow rate l /min 20 40 60 80 100 120 140 160
water flow rate l/min 0 0 0 0 0 0 0 0
Δp (cm H2O) 0.2 0.1 0.2 0.6 1.1 1.8 2.4 4.2
Δp (g/cm.s2) 196 98 196 588 1078 1764 2352 4116
log air flow rate (l/min) 1.301029996 1.60206 1.778151 1.90309 2 2.079181 2.146128 2.20412
log Δp (g/cm.s2) 2.292256071 1.991226 2.292256 2.769377 3.032619 3.246499 3.371437 3.614475
Table (2): data of flow (air + water) and differential pressure at wet
column
wet c olunm
2.5
2
log air flow rate (l/min) Figure (4): graph of log ΔP vs. log air flow.
1.5
1
0.5
0
2.5 2.7 2.9 3.1 3.3 3.5 3.7
log Δp (g/cm.s2)
12

13. .
wet column
air flow rate l /min 20 40 60 80 100 120 140 160
water flow rate l/min 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5
Δp (cm H2O) 0.6 1.2 0.2 0.6 1.6 4.4 6.2 10.6
Δp (g/cm.s2) 588 1176 196 588 1568 4312 6076 10388
log air flow rate (l/min) 1.301029996 1.60206 1.778151 1.90309 2 2.079181 2.146128 2.20412
log Δp (g/cm.s2) 2.769377326 3.070407 2.292256 2.769377 3.195346 3.634679 3.783618 4.016532
Table (3): data of flow (air + water) and differential pressure at 1.5(L/min) of flow
water
water flow rate =1.5 (l/min)
2.5
2
1.5
1
0.5
0
2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1
log Δp (g/cm.s2)
log air flow rate (l/min)
Figure (5): graph of log ΔP vs. log air flow.
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14. wet column
air flow rate l /min 20 40 60 80 100 120 140 160
water flow rate l/min 2 2 2 2 2 2 2 2
Δp (cm H2O) 0.4 0.2 0.2 1.8 3.4 6.4 10.6 20.6
Δp (g/cm.s2) 392 196 196 1764 3332 6272 10388 20188
log air flow rate (l/min) 1.301029996 1.60206 1.778151 1.90309 2 2.079181 2.146128 2.20412
log Δp (g/cm.s2) 2.593286067 2.292256 2.292256 3.246499 3.522705 3.797406 4.016532 4.305093
Table (4): data of flow (air + water) and differential pressure at 2(L/min) of flow
water.
water flow rate =2(l/min)
2.5
2
1.5
1
0.5
0
2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
log Δp (g/cm.s2)
air flow rate l /min
Figure (6): graph of log ΔP vs. log air flow.
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15. .
wet column
air flow rate l /min 20 40 60 80 100 120 140 160
water flow rate l/min 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5
Δp (cm H2O) 0.2 0.2 0.4 2.4 4.8 10.2 11.2 20
Δp (g/cm.s2) 196 196 392 2352 4704 9996 10976 19600
log air flow rate (l/min) 1.301029996 1.60206 1.778151 1.90309 2 2.079181 2.146128 2.20412
log Δp (g/cm.s2) 2.292256071 2.292256 2.593286 3.371437 3.672467 3.999826 4.040444 4.292256
Table (5): data of flow (air + water) and differential pressure at 2.5(L/min) of flow
water
waterflow rate =2.5 (l/min)
2.5
2
1.5
1
0.5
0
2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
log Δp (g/cm.s2)
log air flow rate (l/min)
Figure (7): graph of log ΔP vs. log air flow.
15

16. .
wet column
air flow rate l /min 20 40 60 80 100 120 140 160
water flow rate l/min 3 3 3 3 3 3 3 3
Δp (cm H2O) 3.6 2 0.6 1 4.2 11 20 45
Δp (g/cm.s2) 3528 1960 588 980 4116 10780 19600 44100
log air flow rate (l/min) 1.301029996 1.60206 1.778151 1.90309 2 2.079181 2.146128 2.20412
log Δp (g/cm.s2) 3.547528576 3.292256 2.769377 2.991226 3.614475 4.032619 4.292256 4.644439
Table (6): data of flow (air + water) and differential pressure at 3(L/min) of flow
water
water flow rate=3 (l/min)
2.5
2
1.5
1
0.5
0
1 1.5 2 2.5 3 3.5 4 4.5 5
log Δp (g/cm.s2)
log air flow rate (l/min)
Figure (8): graph of log ΔP vs. log air flow.
16

17. Discussion & Conclusions:
 The pressure difference increased when the air flow and water flow
increased.
 The flooding point decreases as the air flow increases (the high water
flow the gives less flooding point )
 The slope of the flooding curve is decreasing with the increasing
of the water flow rate
17

18. References:
1. Chirstie J.Geankoplis, ( Transport Process and Unit Operation ), 4rd
edition. University of Minnesota, 2003 by person Education,
"Publishing as Prentice Hall Professional Technical Reference",
pages: 645- 650.
2. Warren L. McCabe, Julian C. Smith and Peter Harriott,(UNIT
OPERATION OF CHAMICAL ENGINEERING), 7th edition,
international edition 2005,”published by McGraw-Hill”, Avenue of
the Americas, pages: 565-568.
3. Aziz M. Abu-Khalaf, ( Chemical Engineering Education, CEE 32
(3) ), King Suad University 1998.
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