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
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Table of Contents: Title
Page
Summary
3
Introduction
4
Expierment objective
6
Theory
7
Schematic diagram
8
Experimental procedure Results & Calculation
9 10
Discussion & Conclusion
16
Reference
17
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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 loglog graph between air flow rate VS. Differential pressure.
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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 airammonia 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)
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FIG (1): PACKED TOWER FLOW AND CHARACSTERISTICS FOR ABSORPSTION.
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objective
Expierment
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.
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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.
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SCHEMATIC DIAGRAM :( 3)
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FIG (2): Gas absorption device.
Experimental Procedure: 9
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.
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Result & Calculation:.
dry colunm air flow rate l /min water flow rate l/min Δp (cm H2O) Δp (g/cm.s2) log air flow rate (l/min) log Δp (g/cm.s2)
20 0 0.2 196 1.3010299 96 2.2922560 71
40 0 0.4 392 1.60206 2.59328 6
60 0 0.4 392 1.77815 1 2.59328 6
80 0 0.4 392
100 0 0.3 294
1.90309 2.59328 6
2 2.46834 7
120 0 1.7 1666 2.07918 1 3.22167 5
140 0 2.6 2548 2.14612 8 3.40619 9
Table (1): data of flow (air + water) and differential pressure at dried column
dry colunm 4
3.5
log air flow rate l /min
3
2.5
2
1.5
1
0.5
0 0
0.5
1
1.5
2
2.5
log Δp (g/cm.s2)
Figure (3): graph of log ΔP vs. log air flow.
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160 0 3.8 3724 2.2041 2 3.5710 1
. wet column air flow rate l /min water flow rate l/min Δp (cm H2O) Δp (g/cm.s2) log air flow rate (l/min)
20 0 0.2 196 1.3010299 96 2.2922560 71
log Δp (g/cm.s2)
40 0 0.1 98 1.60206 1.99122 6
60 0 0.2 196 1.77815 1 2.29225 6
80 0 0.6 588
100 0 1.1 1078
1.90309 2.76937 7
2 3.03261 9
120 0 1.8 1764 2.07918 1 3.24649 9
140 0 2.4 2352 2.14612 8 3.37143 7
Table (2): data of flow (air + water) and differential pressure at wet column
wet colunm 2.5
log air flow rate (l/min)
2
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)
Figure (4): graph of log ΔP vs. log air flow. 12
160 0 4.2 4116 2.20412 3.61447 5
. wet column air flow rate l /min water flow rate l/min Δp (cm H2O) Δp (g/cm.s2) log air flow rate (l/min) log Δp (g/cm.s2)
20 1.5 0.6 588 1.3010299 96 2.7693773 26
40 1.5 1.2 1176 1.60206 3.07040 7
60 1.5 0.2 196 1.77815 1 2.29225 6
80 1.5 0.6 588
100 1.5 1.6 1568
1.90309 2.76937 7
2 3.19534 6
120 1.5 4.4 4312 2.07918 1 3.63467 9
140 1.5 6.2 6076 2.14612 8 3.78361 8
Table (3): data of flow (air + water) and differential pressure at 1.5(L/min) of flow water
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160 1.5 10.6 10388 2.20412 4.01653 2
water flow rate =1.5 (l/min) 2.5
log air flow rate (l/min)
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)
Figure (5): graph of log ΔP vs. log air flow.
wet column air flow rate l /min water flow rate l/min Δp (cm H2O) Δp (g/cm.s2) log air flow rate (l/min) log Δp (g/cm.s2)
20 2 0.4 392 1.3010299 96 2.5932860 67
40 2 0.2 196 1.60206 2.29225 6
60 2 0.2 196 1.77815 1 2.29225 6
80 2 1.8 1764
100 2 3.4 3332
1.90309 3.24649 9
2 3.52270 5
120 2 6.4 6272 2.07918 1 3.79740 6
140 2 10.6 10388 2.14612 8 4.01653 2
Table (4): data of flow (air + water) and differential pressure at 2(L/min) of flow water.
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160 2 20.6 20188 2.20412 4.30509 3
water flow rate =2(l/min) 2.5
air flow rate l /min
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)
Figure (6): graph of log ΔP vs. log air flow.
. wet column air flow rate l /min water flow rate l/min Δp (cm H2O) Δp (g/cm.s2) log air flow rate (l/min) log Δp (g/cm.s2)
20 2.5 0.2 196 1.3010299 96 2.2922560 71
40 2.5 0.2 196 1.60206 2.29225 6
60 2.5 0.4 392 1.77815 1 2.59328 6
80 2.5 2.4 2352
100 2.5 4.8 4704
1.90309 3.37143 7
2 3.67246 7
120 2.5 10.2 9996 2.07918 1 3.99982 6
140 2.5 11.2 10976 2.14612 8 4.04044 4
Table (5): data of flow (air + water) and differential pressure at 2.5(L/min) of flow water
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160 2.5 20 19600 2.20412 4.29225 6
waterflow rate =2.5 (l/min) 2.5
log air flow rate (l/min)
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)
Figure (7): graph of log ΔP vs. log air flow.
. wet column air flow rate l /min water flow rate l/min Δp (cm H2O) Δp (g/cm.s2) log air flow rate (l/min) log Δp (g/cm.s2)
20 3 3.6 3528 1.3010299 96 3.5475285 76
40 3 2 1960 1.60206 3.29225 6
60 3 0.6 588 1.77815 1 2.76937 7
80 3 1 980
100 3 4.2 4116
1.90309 2.99122 6
2 3.61447 5
120 3 11 10780 2.07918 1 4.03261 9
140 3 20 19600 2.14612 8 4.29225 6
Table (6): data of flow (air + water) and differential pressure at 3(L/min) of flow water
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160 3 45 44100 2.20412 4.64443 9
water flow rate=3 (l/min) 2.5
log air flow rate (l/min)
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)
Figure (8): graph of log ΔP vs. log air flow.
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 )
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The slope of the flooding curve is decreasing with the increasing
of the water flow rate
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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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