Ammonia Gas Absorption - ww2.che.ufl.eduww2.che.ufl.edu/unit-ops-lab/experiments/GA/GA-NH3/GA-NH3-Manua… · Ammonia Gas Absorption by Oscar D. Crisalle Professor Chemical Engineering

Ammonia Gas Absorption

by

Oscar D. Crisalle

Professor

Chemical Engineering Department

University of Florida

[email protected]

Revision 12: September 24, 2013

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CONTENTS

1 Introduction 4

2 Experiment 1: Absorption of Ammonia (NH3) 5

3 Operational Information 6

4 Thermodynamic Phase-Equilibrium 9

5 Henry's Law 11

6 Gas Densities 12

7 Colburn's NTU Equation 137.1 Number of transfer units for gas-phase controlled transfer . . . . . . . . . . . . . . . . . . . . . . 137.2 Height of a transfer unit for gas-phase controlled transfer . . . . . . . . . . . . . . . . . . . . . . . 147.3 Remarks on the NTU Equation (7) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

8 Overall Mass Transfer Coe�cient 15

9 Interpretation of the Absorption Factor 16

10 Interpretation of NTU and HTU 17

11 Characteristics of Flow in the Column 1811.1 Hold-up time (also called residence time) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1811.2 Number of hold-ups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

12 Scrubbing E�ectiveness 19

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13 Theoretical Expectations 21

14 Measurement of NH3 Gas Compositions 22

15 Rotameter: Water Flow Measurement 2315.1 Liquid solvent rotameter (RTM): water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2315.2 Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

16 Rotameters: Gas Flow Measurements 2516.1 Gas feed-line rotameters (RTM): (NH3 +N2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2516.2 Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

17 Experimental Details 27

18 Experimental Procedures 3018.1 Start-up and normal-operation procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3018.2 Shut-down procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

19 Anticipated Experimental Problems 32

20 Objectives 33

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1 INTRODUCTION

l This experiment investigates the properties of gas absorption equipment where a gaseous

solvent mixed with air or Nitrogen is absorbed by dissolution into a water stream

l There are two gas absorption experiments in the Unit Operations lab

Experiment 1 Absorption of ammonia in water

Experiment 2 Absorption of carbon dioxide in water

l The focus of this lab is the Experiment 1 which deals with the absorption of ammonia in

water.

l It is MANDATORY to read the chapter entitled Gas Absorption in reference [3]

before carrying out this experiment.

l Remark: Gas absorption is also referred to as gas scrubbing, or gas washing.

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2 EXPERIMENT 1: ABSORPTION OF AMMONIA (NH3)

Counter-current absorption packed tower

Ammonia

Sensor

Rotameter

Rotameter

Solvent (W)Raffinate (N2 + NH3)

Feed (N2 + NH3) Extract (W + NH3)

Lout, xout

Lin, xinVout, yout

Vin, yin

h

Nomenclature

l Solute: Ammonia (NH3)

l Feed Carrier Gas: Nitrogen (N2)

l Solvent: Water (W )

Thermodynamic Equilibrium

y = mx*

Equilibrium N2 + NH3

W + NH3

y

x*

Feed-solvent Phase

(or raffinate phase)

Extract-solvent Phase

(or extract phase)

N2 + NH3

W

Assumption: Nitrogen is insoluble in W. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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3 OPERATIONAL INFORMATION

l Column available

m Height of the column : 800 mm

m Internal diameter: 100 mm

m Type of packing: Standard 6 mm Raschig rings

l Density

m The liquid water stream has a higher density than the N2 +NH3 gas stream. That is why

the liquid stream is fed from the top.

l Insolubility

m We are making the assumption that N2 is insoluble in W. This is only an approximation.

l Nonvolatility

m We are making the assumption that the solvent (W ) is nonvolatile at the temperature of

the experimental conditions

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OPERATIONAL INFORMATION

l Continuous and dispersed phases

m Two phases form inside the column: a CONTINUOUS phase and a DISPERSED

phase. When a column is started up, it is FIRST �lled with ONLY the gas. This de�nes

the continuous phase. SECOND, the liquid stream is introduced, and it becomes the

dispersed phase.

m Making the gas the continuous phase creates more interfacial area than when the liquid is

the continuous phase (because the gas is constrained to reside in bubbles)

l Flooding by the water phase

m Occurs when the upward force exerted by the gas is su�cient to prevent the liquid from

�owing downward

m The 100% �ooding velocity of the gas stream can be determined for a given inlet liquid

stream �ow:

n Set the gas feed �ow to a value that �oods the column (water level is at the top of the

packing surface)

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OPERATIONAL INFORMATION

l Operation at 0% �ooding

m Start gas �ow

m Set 100% �ooding conditions

m Progressively reduce the gas �ow rate until a value where zero �ooding (packing base level)

occurs

m Space below packing base must be covered with water to prevent gas escape via the liquid

exit pipe

l In the case of unpacked column

m For 0% �ooding, the height of the column at which the inlet of the feed gas stream is

located should be considered as the base level

m For 100% �ooding, the height of the column at which the inlet of the water solvent stream

is located should be considered as the top level

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4 THERMODYNAMIC PHASE-EQUILIBRIUM

l Some NH3 from the gas phase (Nitrogen + NH3) absorbs into the liquid phase (Water +

NH3) establishing a phase equilibrium after a su�ciently long time

x∗ mole fraction of NH3 in the liquid phase at equilibrium

y mole fraction of NH3 in the gas phase at equilibrium

l The equilibrium mole-fraction (x∗) of absorbed NH3 is known as the solubility of NH3 in

water

N2 + NH3

W + NH3

y

x*

Gas Phase

Liquid Phase

P

T

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THERMODYNAMIC PHASE-EQUILIBRIUM

l The solubility of NH3 in water is high at room temperature and 1 atm of pressure

m The solubility increases with pressure and decreases with temperature

l It is possible to derive a relationship relating x∗ to y, but we are mostly interested in cases

of low values of y (use of dilute mixture of NH3 and nitrogen)

m Focus: dilute gas-phase regime

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5 HENRY'S LAW

l At constant T and at equilibrium, the amount of solute gas that dissolves into the liquid (x∗)

is proportional to the partial pressure (yP ) of the solute gas in the gas phase: i.e,

yP = H(T )x∗ (1)

or

y = mx∗ (2)

where

m =H (T )

P(3)

where P is the operating pressure of the column and

H (298.15) = 0.885 atm

l Valid only for dilute solutions and when the solute (NH3) does not react with the solvent

(W )

l Temperature dependence is given by the van't Ho� equation

H (T ) = H(T ref

)exp

[−C

(1

T− 1

T ref

)](4)

and for NH3/water solution

C = 3670 K

l Resource: http://www.henrys-law.org

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6 GAS DENSITIES

l Standard Temperature and Pressure

m NIST-STP: National Institute of Standards and Technology

T = 20C = 68F = 293.15K P = 1atm = 1.01325 bar = 14.696 psi

m IUIPAC-STP: International Union of Pure and Applied Chemistry

T = 0C = 32 = 273.15K P = 0.9869 atm = 1bar = 14.504 psi

m Gas rotameter manufactures usually use di�erent standards. Refer the instrument manual

for details.

l Density Models

m Density of dry air (model using the speci�c air constant)

ρAir =P

RSpecificAir T

(5)

where P is the feed gas pressure and

RSpecificAir = 286.689 J/ (kg ·K) = 2.829× 10−3m3 · atm/ (kg ·K)

m Density of ammonia gas

ρNH3≈ MWNH3

MWAirρAir =

17.031

29ρAir = 0.587ρAir (6)

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7 COLBURN'S NTU EQUATION

7.1 Number of transfer units for gas-phase controlled transfer

NOG =A

1− Aln

mxin − youtmxin − yin

1− 1

A

(1− mxin − yout

mxin − yin

) (7)

and

A =L′inmV ′in

(8)

where

yout solute mole fraction in the ra�nate [dimensionless]

yin solute mole fraction in the feed [dimensionless]

xin solute mole fraction in the solvent [dimensionless]

A absorption factor [dimensionless]

V ′in = Vin/Across feed molar super�cial velocity[lbmole/

(min · ft2

)]L′in = Lin/Across solvent molar super�cial velocity

[lbmole/

(min · ft2

)]m equilibrium constant for dilute solution [dimensionless]

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COLBURN'S NTU EQUATION

7.2 Height of a transfer unit for gas-phase controlled transfer

HOG =h

NOG(9)

l h is the height of the packed bed [ft]

7.3 Remarks on the NTU Equation (7)

l Only valid for dilute feed streams

l It is assumed that the solute mole fraction in the solvent is zero, i.e., xin = 0

l Number of transfer units is expressed in terms of concentration in the gas phase

m Solubility of ammonia in water is high

l As a result, the dominant resistance to di�usion (mass transfer) resides within the gas

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8 OVERALL MASS TRANSFER COEFFICIENT

l Overall mass transfer coe�cient on a gas-phase basis

Kya =Vin

HOGAcross=

1

HOGV ′in (10)

m Interfacial area per unit volume of packing, a, is normally left lumped with the mass

transfer coe�cient (De�nition: Ainterfacial = aAcross)

l Mass-transfer resistance: inverse of the mass-transfer coe�cient

Resistance =1

Kya(11)

l Correlation (Solve using least-squares regression)

Kya = c1Lc2inV

c3in =⇒ ln (Kya) = c4 + c2 lnLin + c3 lnVin (12)

where c4 = ln c1

m See tutorial on the Excel function LINEST (�Least-squares regression using LINEST in

Excel�) posted in the course web site. You can also use MATLAB or OCTAVE

m Veri�cation of correlation

n Carry out at least one additional experimental run

Error =

∣∣(Kya)correlation − (Kya)run∣∣

(Kya)run100% (13)

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9 INTERPRETATION OF THE ABSORPTION FACTOR

l The Absorption Factor A is de�ned as the ratio of the local slope of the operating curve

to that of the equilibrium curve

A =Slope of operating curve

Slope of equlibrium curve=

(L′in/V′in)

m=

L′inmV ′in

l For the transfer of NH3 from the gas phase (V ) to the liquid phase (L), the driving force

y − y∗ should be positive, which implies the operating line should be above the equilibrium

line.

m This is possible when

A > 1− mxin − youtmxin − yin

m Hence, the absorption of NH3 from the gas phase into the liquid phase occurs only when

the above condition on A is met.

l Observations

m When A < 1 − mxin − youtmxin − yin

mass transfer occurs from the liquid phase into the gas phase

(desorption or stripping)

m When A = 1− mxin − youtmxin − yin

there is no net mass transfer between the gas and liquid phases

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10 INTERPRETATION OF NTU AND HTU

l Number of transfer units (NTU)

m Depend on the value of yout desired for a given yin

m Measure of the di�culty of separation

m If a high-level of absorption (separation) is desired, then a larger number of NTUs is

needed

l Height of a transfer units (HTU)

m Depend on the mass transfer coe�cient and the gas �ow rate

m Measure of the separation e�ectiveness of the packing for the species being absorbed

m HTU is proportional to the resistance to mass transfer

HOG =1

Kya

VinAcross

(14)

m HTU is small (lower resistance) when

n There is a high rate of interface mass transfer

n There is a large amount of interfacial area (better contact)

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11 CHARACTERISTICS OF FLOW IN THE COLUMN

11.1 Hold-up time (also called residence time)

thold−up =VPackQWater

(15)

thold−up hold-up time (residence time) (min)

QWater water (solvent) �ow rate (GPM)

VPack packed volume (gal)

11.2 Number of hold-ups

Nhold−up =tSS

thold−up(16)

Nhold−up number of hold-ups (dimensionless)

tSS time to steady-state (min)

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12 SCRUBBING EFFECTIVENESS

l De�nition of Scrubbing E�ectiveness

ε :=Overall rate of NH3absorption into the liquid solvent

Rate of NH3entering via the feed stream(17)

l Formula Derivation: De�ne

Y =youtyin

(18)

and use the mass-balance result Vout =1− yin1− yout

Vin:

ε =yinVin − youtVout

yinVin=

yinVin − yout(

1− yin1− yout

Vin

)yinVin

=yin (1− yout)− yout (1− yin)

yin (1− yout)=

yin − youtyin (1− yout)

=

1− youtyin

1− yinyoutyin

=1− Y

1− yinY

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l Calculation

m 1. From experimental data

Information needed: yin and youtProcedure:

n Calculate

Y exp =youtyin

(19)

n Calculate

εexp =1− Y exp

1− yinY exp(20)

m 2. From NTU predictions

Information needed: yin, m, Vin, Lin, and NOG

Procedure

n Calculate A and �nd the value of Y by solving (graphically or numerically) from

NOG =A

A− 1ln

1 +1

Y(A− 1)

A(21)

n Calculate

εpred =1− Y

1− yinY(22)

m 3. Prediction error

n Calculate the prediction error PE

PE =

∣∣εpred − εexp∣∣εexp

100% (23)

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13 THEORETICAL EXPECTATIONS

l The mass transfer should increase for larger Lin/Vin ratios

l The mass transfer should more strongly a�ected by the gas-feed �ow rate (Vin) than by the

solvent �ow rate (Lin)

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14 MEASUREMENT OF NH3 GAS COMPOSITIONS

l BACHARACH Ammonia gas monitor:

Model AGMSZ

l Measures ammonia gas in the range of 25

to 10, 000 ppm

l Detector Type: Single pass, non-

dispersive infrared

l Sensitivity: 25 ppm

l Accuracy: ±10 ppm ± 10% of reading

from 0− 1000 ppm

l Response Time: 9 to 30 seconds, depend-

ing on tube length and gas concentration

l Operating Temperature: 32 to 122°F (0

to 50°C)

l Operating Humidity: 5 to 90% RH, non-

condensing

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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15 ROTAMETER: WATER FLOW MEASUREMENT

15.1 Liquid solvent rotameter (RTM):

water

l Dwyer Rate-Master Flowmeter: Model

RMC

l 2 rotameters (coarse and �ne adjust-

ments)

l Measurement units

m Coarse: Gallons per Minute (GPM)

m Fine: Gallons per Hour (GPH)

Coarse Fine

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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ROTAMETER: WATER FLOW MEASUREMENT

15.2 Measurements

l Reading: QRTM,solvent (graduation mark on the scale)

l For �ne rotameter

Qsolvent(GPH) = QRTM,solvent (24)

l For coarse rotameter

Qsolvent(GPH) =60 min

1 hrQRTM,solvent (25)

l Mass �ow rate

Qsolvent(lb/hr) = ρsolventQsolvent(GPH) (26)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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16 ROTAMETERS: GAS FLOW MEASUREMENTS

16.1 Gas feed-line rotameters (RTM):

(NH3 + N2)

l Dwyer Rate-Master Flowmeter: Model

RMB

l 2 rotameters (coarse and �ne adjust-

ments)

l Measurement units: �Standard� Cubic

Feet per Hour (SCFH)

Coarse Fine

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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ROTAMETERS: GAS FLOW MEASUREMENTS

16.2 Measurements

l Reference (from the instrument manual)

m Tref = 70 F = 21.111 C = 294.261 K

m Pref = 1 atm = 1.01325 bar = 14.696 psi

l Reading: RRTM (�oat position on the scale)

Qfeed(SCFH) = RRTM

√PfeedPref

Tref(K)

Tfeed(K)(27)

Qfeed(lb/hr) = fSCFH→CFH ρfeed Qfeed(SCFH) (28)

where the conversion factor fSCFH→CFH is

fSCFH→CFH =PrefPfeed

Tfeed(K)

Tref(K)(29)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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17 EXPERIMENTAL DETAILS

l Because NH3 is highly soluble in water, one must operate at low solvent-to-feed rations

(i.e., low L/V) to prevent complete mass transfer to the liquid (dominant resistance to mass

transfer is in the gas phase)

l Measure the NH3 composition in the feed and ra�nate stream using the sensor.

m Take repeated measurements to obtain statistical averages.

m Report concentration values at steady state (take great care of ensuring steady state is

attained)

l Measure the volumetric mass �ow rates of the the feed and solvent streams using the rotame-

ters and convert the readings to mass and molar �ow rates [lbmol/hr].

m Then calculate the corresponding �uxes need in Colburn's equation by dividing by the

cross sectional area of the column.

l Determine the �ooding velocity of the feed stream for each solvent �ow rate considered.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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EXPERIMENTAL DETAILS

l Run the column at various values of the absorption coe�cient.

l Note also that at steady state the NH3 composition in the extract stream is estimated from

the following expression (obtained from a mass balance)

xout =yinVin − youtVout

Lout(30)

where Vout is obtained from yet another mass-balance calculation as

Vout =1− yin1− yout

Vin (31)

l Assumptions

m The NH3/N2 mixture behaves as an ideal-gas mixture

m The solvent stream contains no absorbed NH3 on inlet to the column

m The extract stream contains no absorbed nitrogen

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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EXPERIMENTAL DETAILS

l Example of a data record

m Consider recording your data in a table similar to the one shown below

Run T QRTM,feed QRTM,solvent yin yout ∆P · · ·

1

2

3

4

5

...

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18 EXPERIMENTAL PROCEDURES

18.1 Start-up and normal-operation procedures

1. Plug the power cable of the NH3 sensor into the outlet.

2. Open the valve for the water outlet (extract) line.

3. Open fully the feed-gas cylinder (N2 + NH3). Set the regulator pressure to the desired

setting. (Note: the pressure should not exceed 40 psi)

4. Adjust the rotameters to allow the desired �ow of feed gas �ow into the column.

5. Open the water inlet valve and adjust the rotameters to obtain the desired solvent (water)

�ow into the column. DO NOT allow water into the column when the feed �ow rate is zero,

as water might enter into the feed gas line until it reaches and damages the NH3 sensor.

6. Switch on the di�erential pressure gauge to measure the pressure drop across the column.

7. Open the appropriate sensor gas-valves to measure the concentration of NH3 in either the

feed stream or the ra�nate stream.

8. During operation always maintain the water level at the bottom of the column below the

feed-gas inlet to prevent feed gas escaping the column through the extract-stream opening.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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EXPERIMENTAL PROCEDURES

18.2 Shut-down procedure

1. Turn o� the solvent �ow into the column by closing the water valve completely.

2. Close completely the valve of the feed-gas cylinder (N2 + NH3).

Important note: DO NOT turn o� the feed gas before turning o� the water.

3. Wait for the feed-gas and water �ow into the column to go to zero on the rotameter

scales; then turn o� the rotameters.

(Closing the inlet valves of water and feed gas before turning o� the rotameters helps

to release the pressure in the inlet lines in shut-down mode)

4. Switch o� the pressure gauge.

5. Unplug the Ammonia sensor from the power outlet.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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19 ANTICIPATED EXPERIMENTAL PROBLEMS

l Incorrect start-up sequence (creates the wrong dispersed phase)

l Not waiting su�ciently for steady-state conditions

l Experiments may not have been carried out at isothermal conditions

l The feed gas may escape through the extract outlet when a small amount of water level is

not maintained at the extract outlet

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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20 OBJECTIVES

NOTE: Address ONLY the objectives identi�ed by the instructor (ignore the rest)

l Objective 1

m Characterize the �ooding condition of the column at each liquid �ow rate by determining

the �ooding gas �ow rate. Plot the �ooding gas �ow rate as a function of (a) liquid �ow

rate, (b) the liquid-to-gas molar �ow ratios, and (c) the absorption factor A

l Objective 2

m Determine the hold-up time and the number of hold-up times needed to achieve steady-

state as a function of absorption factor A.

l Objective 3

m Characterize the dependence of NTUs and HTUs on the absorption factor A: (a) Plot the

NTU and HTU results as a function of A, (b) Plot the natural logarithm of the NTU and

HTU results as a function of A.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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OBJECTIVES

l Objective 4

m Characterize the mass transfer coe�cient

n Find a correlation for the mass transfer coe�cient and verify the correlation using

additional experimental test

n Establish the dependence of the mass transfer coe�cient on the absorption factor A: (a)

Plot the mass transfer coe�cient as a function of A, (b) Plot the natural logarithm of

mass transfer coe�cient as a function of A. Superimpose on these plots the correlation

curve

l Objective 5

m Plot the the scrubbing e�ectiveness as a function of A as a function of the NTUs.

l Objective 6

m Plot the ra�nate and the extract compositions as a function of A

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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REFERENCES

[1] Hodgman, C. D., Weast R. C., and Selby, S. M., editors, CRC Handbook of Chemistry and

Physics, 42nd edition. CRC Press, Cleveland Ohio, (1961).

[2] Geankoplis, C. J., Transport Processes and Unit Operations, Third Edition. Prentice-Hall Inc.,

Englewood Cli�s, NJ (1990). (Chapter 10)

[3] McCabe, W. L., J. C. Smith, and P. Harriet, Unit Operations of Chemical Engineering, Fifth

Edition. McGraw-Hill, Inc., New York, NY (1993). (Chapter 22)

[4] Foust, A. S., L. A. Wenzel, C. V. Clump. L. Maus. and L. B. Anderson, Principles of Unit

Operations. John Wiley & Sons, New York, 1960. page 552.

[5] Onda, K., Takeuchi, H., and Okumoto, Y, Mass transfer coe�cients between gas and liquid

phases in packed columns, Journal of Chemical Engineering of Japan, Vol 1, pp. 56�62 (1968).

[6] Treybal, R. E., Mass Transfer Operations, 2nd. ed., McGraw-Hill, New York (1968).

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