*
Types of Separation Processes and Methods
Equilibrium Relations between Phases
Mass Transfer between Phases
Continuous Humidification Processes
Single and Multiple Equilibrium Contact Stages
Absorption in Plate and Packed Towers
Absorption of Concentrated Mixtures in Packed Tower
CHAPTER 10: GAS - LIQUID SEPARATION PROCESSES OVERVIEW
MASS TRANSFER BETWEEN PHASES*
*The solute A transferred from the fluid phase by convection mass transfer and through the solid by diffusion Concentration profiles in interface mass transferMass Transfer Between Phases
*Equimolar counterdiffusion
Mass Transfer Between Phases using film mass transfer coefficients and interface concentration
*Diffusion of A through stagnant or nondiffusing B Mass Transfer Between Phases using film mass transfer coefficients and interface concentration
*Mass Transfer Between Phases using film mass transfer coefficients and interface concentration
*EXAMPLE 10.4-1System boundaryQinThe solute A is being absorbed from a gas mixture of A and B in a wetted wall tower with the liquid flowing as a film downward along the wall. At a certain point in the tower the bulk gas concentration yAG=0.380 mol fraction and the bulk liquid concentration is xAL=0.100. The tower is operating at 298K and 1.013x105 Pa and the equilibrium data are tabulated in the table.The solute A diffuses through stagnant B in the gas phase and then through a nondiffusing liquid.Using correlations for dilute solutions in wetted wall towers, the film mass transfer coefficient for A in the gas phase is predicted as ky=1.465x10-3 kgmol A/s.m2.mol fraction liquid phase as kx=1.967x10-3 kgmol A/s.m2.mol fractionCalculate the interface concentrations yAi and xAi and flux NA.
*Since dilute solutions, (1-yA)iM 1.0 and (1-xA)iM 1.0Therefore,k`y=ky and k`x=kxEquilibrium data are plotted in figure 10.4-4.Point P:yAG = 0.380xAL = 0.100First trial,(1-yA)iM = 1.0(1-xA)iM = 1.0Slope PM (from Equation 10.4-9)
EXAMPLE 10.4-1 : solutionA line through point P with a slope of 1.342 is plotted intersecting the equilibrium line at M1. Point M1yAi=0.183xAi=0.247
*Second trial, use yAi and xAi from first trial to calculate the new slope.
Substituting into Eqs. (10.4-6) and (10.4-7),
Substituting into Eq.(10.4-9) to obtain the new slope,
A line through point P with a slope of 1.163 is plotted intersecting the equilibrium line at M. Point MyAi = 0.197xAi = 0.257
*Third trial, use yAi and xAi from second trial to calculate the new slope.
Substituting into Eqs. (10.4-6) and (10.4-7),
Substituting into Eq.(10.4-9) to obtain the new slope,
This slope is the same as the slope for 2nd trial.Final values:At point MyAi = 0.197xAi = 0.257
*To calculate the flux (Equation 10.4-8) is used.
*yAGxALPyAixAiM1M
Chart4
00.11160.1830.1830.0632110.380.380.1970.197
0.0220.18300.1830.19700.197
0.052
0.087
0.131
0.187
0.265
0.385
Equilibrium Line
Line PM1
Line PM
10.4-1
Equilibrium Line
xAyA
0.000
0.050.022
0.100.052
0.150.087
0.200.131
0.250.187
0.300.265
0.350.385
Point PPoint M1
yAGslope(m)csetting xsetting yxAiyAi
0.1000.380-1.3420.51420.30.11160.2470.1830.2470.183
0.2470
Line PM1
0.1000.3800.2470.183
0.2470.18300.183
Point M1Point M
xAiyAislope(m)csetting xsetting yxAiyAi
0.2470.183-1.1630.4702610.350.0632110.2570.1970.2570.197
0.2570
Line PM
0.1000.3800.2570.197
0.2570.19700.197
10.4-1
Equilibrium Line
Line PM1
Line PM
10.4-1PowerPT
Equilibrium Line
xAyA
0.000
0.050.022
0.100.052
0.150.087
0.200.131
0.250.187
0.300.265
0.350.385
Point PPoint M1
yAGslope(m)csetting xsetting yxAiyAi
0.1000.380-1.3420.51420.30.11160.2470.1830.2470.183
0.2470
Line PM1
0.1000.3800.2470.183
0.2470.18300.183
Point M1Point M
xAiyAislope(m)csetting xsetting yxAiyAi
0.2470.183-1.1630.4702610.350.0632110.2570.1970.2570.197
0.2570
Line PM
0.1000.3800.2570.197
0.2570.19700.197
P
M1
M
10.4-1PowerPT
Equilibrium Line
Line PM1
Line PM
10.4-2
Equilibrium Line
xAyA
0.000
0.050.022
0.100.052
0.150.087
0.200.131
0.250.187
0.300.265
0.350.385
Point PPoint M1
yAGslope(m)csetting xsetting yxAiyAi
0.1000.380-1.3420.51420.30.11160.2470.1830.2470.183
0.2470
Line PM1
0.1000.3800.2470.183
0.2470.18300.183
Point M1Point M
xAiyAislope(m)csetting xsetting yxAiyAi
0.2470.183-1.1630.4702610.350.0632110.2570.1970.2570.197
0.2570
Line PM
0.1000.3800.2570.197
0.2570.19700.197
Overall Driving VorcexLy*
0.1000.3800.1000.052
0.10000.0000.052
10.4-2
Equilibrium Line
Line PM1
Line PM
10.5-EX
Equilibrium Line(Hyi1-Hy1)-(Hyi2-Hy2)Hy2-Hy1
TLHy(Hyi)10-3(Hy)10-3(Hyi-Hy)10-3ln[(Hyi1-Hy1)/Hyi2-Hy2)](Hyi-Hy)M
26.78494.471.722.723.78304355690.4961518055
29.497.2108.483.524.927.13504749390.4201208788
32.3112.1124.494.929.532.31329174290.3589854012
35128.9141.8106.535.339.35068776250.3024089457
37.8148.2162.1118.443.749.04081211390.2344985636
40.6172.1184.7129.954.8
43.3197.21.8121655948
46.1224.5
Operating Line
TLHy
29.471.7
43.3129.9
yxslopeintersectsettingsetting
HyTLmcxy
71.729.3995844379-41.871302.66060041562988.4306004156
83.532.2177640849-41.871432.457782235931134.4877822359
94.934.9404122185-41.871557.855059587834134.2750595878
106.537.7108261088-41.871685.452289173936178.1322891739
118.440.5528886341-41.871816.349447111439183.4194471114
129.943.2994196461-41.871942.846700580442184.3067005804
P
M1
M
E
10.5-EX
0
0
0
0
0
0
0
0
Equilibrium Line
Liquid Temperature (oC)
Enthalpy Hy [(J/kg)10-3]
10.5-1
Equilibrium Line(Hyi1-Hy1)-(Hyi2-Hy2)Hy2-Hy1
TLHy(Hyi)10-3(Hy)10-3(Hyi-Hy)10-3ln[(Hyi1-Hy1)/Hyi2-Hy2)](Hyi-Hy)M
26.78494.471.722.723.78304355690.4961518055
29.497.2108.483.524.927.13504749390.4201208788
32.3112.1124.494.929.532.31329174290.3589854012
35128.9141.8106.535.339.35068776250.3024089457
37.8148.2162.1118.443.749.04081211390.2344985636
40.6172.1184.7129.954.8
43.3197.21.8121655948
46.1224.5
Operating Line
TLHy
29.471.7
43.3129.9
yxslopeintersectsettingsetting
HyTLmcxy
71.729.3995844379-41.871302.66060041562988.4306004156
83.532.2177640849-41.871432.457782235931134.4877822359
94.934.9404122185-41.871557.855059587834134.2750595878
106.537.7108261088-41.871685.452289173936178.1322891739
118.440.5528886341-41.871816.349447111439183.4194471114
129.943.2994196461-41.871942.846700580442184.3067005804
10.5-1
0000
0000
000
000
000
000
0
0
Equilibrium Line
Operating line
Liquid Temperature (oC)
Enthalpy Hy [(J/kg)10-3]
10.7-1
Operating Line
xy
00.02
0.0003320.04
0.0008550.07
0.002010.13
0.003550.2
Equilibrium Line
xy
00
0.00014030.00158
0.0004220.00763
0.0008420.01855
0.0019650.0513
0.00420.121
0.006980.212
0.000460.009
00.02
0.001030.0235
0.0003320.04
0.001850.0476
0.0008550.07
0.003550.1015
0.002010.13
0.005650.1685
0.003550.2
10.7-1
000000
000000
00
00
00
0
0
Equilibrium Line
Operating Line
mole fraction, x
mole fraction, y
Sheet1
f(y)y
19.250.020.0219.25
12.770.040.020
9.290.07
7.160.130.0412.77
6.330.200.040
0.079.29
0.070
0.137.16
0.130
0.26.33
0.20
Sheet1
000000
000000
0
0
0
y
f(y)
examplePP
Equilibrium Line(Hyi1-Hy1)-(Hyi2-Hy2)Hy2-Hy1
TLHy(Hyi)10-3(Hy)10-3(Hyi-Hy)10-3ln[(Hyi1-Hy1)/Hyi2-Hy2)](Hyi-Hy)M
26.78494.471.722.723.78304355690.4961518055
29.497.2108.483.524.927.13504749390.4201208788
32.3112.1124.494.929.532.31329174290.3589854012
35128.9141.8106.535.339.35068776250.3024089457
37.8148.2162.1118.443.749.04081211390.2344985636
40.6172.1184.7129.954.8
43.3197.21.8121655948
46.1224.5
Operating Line
TLHy
29.471.7
43.3129.9
yxslopeintersectsettingsetting
HyTLmcxy
71.729.3995844379-41.871302.66060041562988.4306004156
83.532.2177640849-41.871432.457782235931134.4877822359
94.934.9404122185-41.871557.855059587834134.2750595878
106.537.7108261088-41.871685.452289173936178.1322891739
118.440.5528886341-41.871816.349447111439183.4194471114
129.943.2994196461-41.871942.846700580442184.3067005804
examplePP
Equilibrium Line
Operating line
Liquid Temperature (oC)
Enthalpy Hy [(J/kg)10-3]
*Equimolar counterdiffusion and/or diffusion in dilute solutions
GAS CONTROLLING LIQUID CONTROLLINGMass Transfer Between Phases Overall mass transfer coefficients and driving forces
*
*Diffusion of A through stagnant or nondiffusing B
Mass Transfer Between Phases Overall mass transfer coefficients and driving forces
Chapter 2 : Work and HeatChapter 2 : Work and Heat*Chapter 2 : Work and HeatChapter 2 : Work and Heat*Chapter 2 : Work and HeatChapter 2 : Work and Heat*Chapter 2 : Work and HeatChapter 2 : Work and Heat*Chapter 2 : Work and HeatChapter 2 : Work and Heat*Chapter 2 : Work and HeatChapter 2 : Work and Heat*Chapter 2 : Work and HeatChapter 2 : Work and Heat*Chapter 2 : Work and HeatChapter 2 : Work and Heat*