Ind. Eng. Chem. Res. 1998, 37, 569-575
569
Mass Transfer Coefficients and Correlation for CO2 Absorption into
2-Amino-2-methyl-1-propanol (AMP) Using Structured Packing
Adisorn Aroonwilas and Paitoon Tontiwachwuthikul*
Process Systems Laboratory, Faculty of Engineering, University of Regina,
Regina, Saskatchewan, Canada S4S 0A2
The volumetric overall mass transfer coefficient (KGav) for CO2 absorption into aqueous solutions
of 2-amino-2-methyl-1-propanol (AMP) was investigated with an absorption column packed with
laboratory structured packings. The KGav value was evaluated over ranges of main operating
variables; that is, up to 10 kPa partial pressure of CO2, 46.2-96.8 kmol/(m2 h) gas molar flux,
6.1-14.6 m3/(m2 h) liquid loading, and 1.1-3.0 kmol/m3 liquid concentration. To allow the mass
transfer data to be readily utilized, an empirical KGav correlation for this system was developed.
The values of mass transfer coefficient for the CO2-AMP system using a random and the tested
structured packings are also compared. For a given system and operating conditions, the
structured packing provides, in general, more than eightfold higher overall KGav values compared
with those of commercial random packings.
1. Introduction
Carbon dioxide (CO2) is considered an important
commercial gas consumed by industry. The CO2 gas can
be produced by the CO2 absorption process, which
consists of absorbing CO2 from gas phase into a liquid
solvent in an absorber and liberating the absorbed CO2
from the solvent at the regeneration unit. Successive
operations of the CO2 absorption process would be
achieved by using effective absorption solvents. The
most commonly used absorption solvents are alkanolamines, which were discovered in the late 1920s by
Robert Roger Bottoms (Maddox, 1982; Astarita et al.,
1983). These alkanolamines can be classified into three
chemical categories: primary, secondary, and tertiary
amines. According to DuPart et al. (1993), the most
popular solvent is monoethanolamine (MEA), which
belongs to the primary chemical class. This is primarily
due to its high reactivity with CO2. Recently, a new
class of acid gas-treating solvents called sterically
hindered amines has been introduced by Exxon Research and Engineering Company (Kohl and Riesenfeld,
1985). Of these hindered amines, 2-amino-2-methyl-1propanol (AMP) is the most promising solvent because
it has the same hindered form as the primary amine
MEA. On the basis of stoichiometry, AMP can react
with CO2 at a theoretical ratio of 1 mol CO2/mol of
amine (Kritpiphat and Tontiwachwuthikul, 1996). This
ratio is a superior characteristic of the hindered amine
compared with the conventional MEA whose theoretical
reaction ratio is only 0.5 mol CO2/mol amine. In
addition to its outstanding absorption capacity, AMP
induces less corrosion, which is considered the major
operational problem in the conventional CO2 absorption
plants (Veawab, Tontiwachwuthikul, and Bhole, 1996).
However, use of the hindered amine AMP is limited by
its reactivity with CO2. Compared with conventional
MEA, AMP has a relatively low rate of CO2 absorption
(Alper, 1990).
* Author to whom correspondence should be addressed.
Telephone: (306) 585-4726. Fax: (306) 585-4855. E-mail:
[email protected].
The use of high-efficiency column internals is an
alternate approach to using highly reactive solvents that
would allow successive absorption operations in small
column dimensions. At present, there are many different types of gas-liquid contactors developed for gas
treating purposes, and the majority of those used are
either packed or tray towers. Considering packed
towers, column internals may be classified into random
(dumped) and structured (ordered) packings. In comparison with the random type, the structured packings
provide a superior performance in term of mass transfer
characteristics. Documentation of the excellent performance of structured packings used in absorption and
distillation applications has been published (Zanetti et
al., 1985; Sulzer, 1987; Kean et al., 1991; Hausch et al.,
1992), basically suggesting that the use of structured
packing would improve the mass transfer performance
in a CO2-AMP absorption system.
The primary objective of this study was to obtain the
mass transfer performance of the CO2 absorption process using structured packing and aqueous solutions of
AMP as the column internal and absorption solvents,
respectively. The performance of the process is presented in terms of the volumetric overall mass transfer
coefficient (KGav). An empirical KGav correlation for this
system was also developed to allow the mass transfer
data to be readily utilized.
2. Determination of Overall Mass Transfer
Coefficient (KGav)
The mass flux of component A (NA) transferring from
a gas stream to a liquid bulk at a steady state can be
expressed in terms of gas-side mass transfer coefficient
kG, total system pressure P, and gas phase driving force
(Treybal, 1980):
NA ) kGP(yA - yA,i)
(1)
where yA and yA,i represent mole fraction of component
A in the gas bulk and that on the gas-side of the gasliquid interface, respectively. In fact, the mass transfer
driving force (yA - yA,i) takes place over extremely small
S0888-5885(97)00482-X CCC: $15.00 © 1998 American Chemical Society
Published on Web 02/02/1998
570 Ind. Eng. Chem. Res., Vol. 37, No. 2, 1998
distances; thus, it is in practice difficult to determine
the concentration of component A at the gas-liquid
interface. Only concentrations in the main body of the
fluids can be determined. Therefore, it is more practical
to express the mass flux in terms of the overall mass
transfer coefficient (KG) and equilibrium mole fraction
of component A in gas phase (yA*) as follows:
NA ) KGP (yA - yA*)
(2)
The relationships between the overall mass transfer
coefficient and the individual-phase coefficients can be
given as follows:
1/KG ) (1/kG) + (H/kL)
(3)
where H and kL are Henry’s law coefficient and liquidside mass transfer coefficient, respectively. In case of
chemical absorption, such as CO2 absorption into an
amine solution, the overall coefficient can be expressed
as a function of the term called enhancement factor I:
1/KG ) (1/kG) + (H/Ik°L)
(4)
where k°L denotes the liquid-side mass transfer coefficient without chemical reactions. In a gas-absorption
apparatus such as packed column, the effective gasliquid interfacial area (av) is considered another important parameter in mass transfer process in addition to
the mass transfer coefficients. Therefore, it is more
practical to present rates of absorption in terms of
transfer coefficients based on a unit volume of the
absorption column rather than on an interfacial area
unit as follows:
1/KGav ) (1/kGav) + (H/Ik°Lav)
(5)
Apparently, the overall coefficient KGav can be directly
determined from eq 5. However, this approach is not
extensively used because experimental determinations
of the individual mass transfer coefficients involve the
use of extremely difficult techniques. A more practical
approach that can be used for the overall coefficient
determination is performing absorption experiments
where the concentration profile of absorbed component
in gas phase must be measured along the test column.
Considering an element of column with height Z, the
mass balance can be given as follows:
NAav dZ ) GI d[yA/(1 - yA)]
(6)
KGavP(yA - yA*) dZ ) GI dYA
(7)
where GI represents inert gas molar flux and YA is the
mole ratio. From eq 7, the overall mass transfer
coefficient per unit volume of packing (KGav) can be
defined as follows:
KGav ) {GI/[P(yA - yA*)]} {dYA/dZ}
(8)
In this study, CO2 absorption was conducted in a
tested column packed with structured packing. The
CO2 concentration in the gas phase along the column
was measured, interpreted in term of mole ratio (YA)
and subsequently plotted as functions of column height
(Z); this plot is called the CO2 concentration profile. The
slope of the profile, expressing concentration gradient
Figure 1. Experimental apparatus for CO2 absorption.
(dYA/dZ) at a particular yA, is then used for evaluating
the KGav value according to eq 8.
3. Experimental Section
Experimental Apparatus. Figure 1 shows the
experimental equipment used in the study. The absorption experiments were performed in a 1.77-m high
and 0.019-m i.d. structured packed column. The column
shell was made of acrylic plastic. The packing, which
is EX type laboratory structured packing provided by
Sulzer Brothers Limited, Winterthur, Switzerland, was
made of 316 stainless steel. The total height of the
packing section was ∼1.10 m. To achieve maximum
performance, the structured packing was placed with
each layer rotated by 90° with respect to the previous
one. Because the gas concentration profile along the
absorption column is required, as mentioned earlier, the
absorption column was designed in such a way that the
gas phase could be sampled through sampling points
at different column levels.
Auxiliary equipment, such as liquid feed and storage
tanks, digital gas flowmeters, and a liquid rotameter,
were used in this work. The 20-dm3 liquid feed and
storage tanks, made of high-density polyethylene, were
purchased from Canadawide Scientific Ltd. Two calibrated mass flowmeters (Aalborg Instruments & Controls Inc.; model GFM 17) were used to measure the air
and CO2 flow rates. The maximum measurable flow
rates were 15.00 and 2.00 (std) dm3/min for air and CO2,
respectively. The rotameter used for measuring liquid
flow rates was made from stainless steel to reduce the
corrosion problem. The maximum measurable flow rate
of the rotameter was 132 cm3/min.
Experimental Procedure. The CO2 absorption
experiments commenced by preparing the AMP solutions at the desired concentration. Air from a major
supply line and CO2 from a cylinder were introduced
through the mass flowmeters at the desired rates,
mixed, and flowed in the same gas line into the bottom
Ind. Eng. Chem. Res., Vol. 37, No. 2, 1998 571
Table 1. Experimental Results for CO2-AMP System
CO2 concentration
in gas phase (%)
CO2 loading in
liquid phase (mol/mol)
run (#)
gas molar flux
(kmol/(m2 h))
liquid loading
(m3/(m2 h))
AMP conc.
(kmol/m3)
column
top
column
bottom
column
top
column
bottom
mass balance
(%)
TL-201
TL-202
TL-203
TL-204
TL-205
TL-206
TL-207
TM-201
TM-202
TM-203
TM-204
TM-205
TM-206
TM-207
TH-201
TH-202
TH-203
TH-204
TH-205
TH-206
TH-207
TH-208
TH-209
TH-210
TH-211
46.2
46.2
46.2
46.2
46.2
48.7
56.5
71.3
71.3
71.3
71.3
71.3
71.3
71.3
96.8
96.8
96.8
96.8
96.8
96.8
96.8
96.8
96.8
96.8
96.8
9.7
9.7
9.7
9.7
9.7
14.6
9.7
9.7
6.1
7.4
10.0
9.7
9.7
9.7
9.7
9.7
9.7
9.7
9.7
12.2
14.6
5.9
7.3
9.7
12.1
1.14
1.14
1.14
1.14
1.14
2.02
3.00
1.14
2.02
2.02
2.02
2.95
2.95
2.98
1.14
1.14
1.14
1.14
2.00
2.00
2.00
2.02
2.02
2.02
2.02
7.35
5.70
4.50
2.20
0.55
6.65
8.90
6.00
7.40
7.00
5.60
4.45
7.50
9.45
8.50
6.50
4.50
2.25
8.10
7.00
6.10
10.00
9.60
8.90
8.60
15.15
13.30
11.85
9.45
4.70
13.95
13.70
11.50
13.90
13.90
13.90
15.00
13.70
13.70
12.10
10.10
7.80
5.70
14.00
14.00
14.00
12.10
12.10
12.10
12.10
0.027
0.027
0.027
0.027
0.037
0.368
0.439
0.000
0.026
0.026
0.026
0.008
0.272
0.405
0.000
0.000
0.000
0.000
0.037
0.037
0.037
0.368
0.368
0.368
0.368
0.449
0.423
0.402
0.364
0.227
0.524
0.557
0.437
0.475
0.418
0.373
0.316
0.461
0.541
0.395
0.383
0.331
0.331
0.421
0.397
0.367
0.578
0.565
0.559
0.535
+1.98
+2.16
+3.00
-1.35
+3.91
+4.70
+0.46
+2.67
-4.39
-4.75
-4.29
-4.49
-1.98
+1.32
+0.94
+2.31
+1.10
+1.10
+3.58
-4.75
+1.90
-1.90
-4.43
-2.80
-3.25
of the column. At this point, the prepared solution from
the feed tank was pumped to the top of the column at
the desired flow rate. This procedure brought both gas
and liquid phases into contact counter-currently, and
CO2 in the gas phase was then absorbed. The exit gas,
containing a low CO2 content, finally left the column at
the top, and the CO2-rich solution, leaving from bottom
of the column, was collected in the storage tank.
Each absorption experiment was operated until steadystate conditions were reached, which normally takes
∼20-30 min when the gas-phase CO2 concentration
profile along the column was measured and recorded.
This CO2 concentration was determined by an infrared
(IR) gas analyzer (model 301D, Nova Analytical Systems
Inc., Hamilton, Ontario, Canada), that was installed as
close as possible to the sampling point. During the
experiments, the gas compositions at different levels
along the absorption column were sampled by switching
the sampling point from one port to another, and
readings were taken after a steady state for each level
was reached.
To verify the CO2 absorption rates calculated from the
gas phase CO2 concentration profile, the CO2-rich solution at the column bottom was simultaneously sampled
and then used for analyzing the amount of absorbed CO2
in the liquid phase. The CO2 content in the liquid
sample was then determined by the standard method
given by the Association of Official Analytical Chemists
(AOAC). This method involved acidifying a precisely
measured quantity of the sample by adding excess HCl
solution. The CO2 gas released was collected in a
precision gas burette. The amount of released CO2 was
later used to calculate the CO2 loading of the amine
solution.
4. Results and Discussion
Twenty-five runs of the absorption experiments were
conducted in this study. The experimental results are
given in Table 1, which includes mass balance percent-
Figure 2. Effect of CO2 partial pressure on overall mass transfer
coefficient, KGav (AMP concentration ) 1.1 kmol/m3, CO2 loading
) 0.15, and liquid loading ) 9.73 m3/(m2 h)).
ages that present differences between the amount of
CO2 removed from gas phase and that absorbed in liquid
phase. These results were plotted as profiles of CO2
concentration (which was converted to a term of mole
ratio, YA) and liquid composition along the packed
column and were subsequently interpreted in term of
the overall mass transfer coefficient (KGav) according to
eq 8. These KGav values are reported as functions of
the main operating variables, namely CO2 partial pressure, gas molar flux, liquid loading, and liquid composition. The KGav values for structured packing and
random packing are also compared.
Overall Mass Transfer Coefficient KGav and
Operating Variables. The effect of CO2 partial pressure on the overall KGav value for CO2 absorption using
AMP solution is graphically illustrated in Figure 2. The
value tends to move upwards when the partial pressure
of CO2 decreases from 10.0 to 3.0 kPa. However, the
effect is not quite significant, especially within the range
6.0-10.0 kPa.
572 Ind. Eng. Chem. Res., Vol. 37, No. 2, 1998
Figure 3. Effect of gas molar flux on overall mass transfer
coefficient, KGav (AMP concentration ) 1.1 kmol/m3, CO2 loading
) 0.15, CO2 partial pressure ) 8.0 kPa, and liquid loading ) 9.73
m3/(m2 h)).
Figure 4. Effect of liquid loading on overall mass transfer
coefficient, KGav (AMP concentration ) 2.0 kmol/m3).
In addition to the influence of CO2 partial pressure,
Figure 2 also shows that variation in gas molar flux does
not affect the mass transfer coefficient. This result is
presented in Figure 3, where the gas molar flux varies
from 46.2 to 96.8 kmol/(m2 h). This lack of effect of gas
molar flux indicates that the mass transfer process in
this case is primarily controlled by the resistance
residing in the liquid phase; therefore, further experiments need not consider the effect of changes in the rate
of gas flow.
Rate of liquid irrigation through the packing is
another factor that affects the value of KGav for the
CO2-AMP system. Figure 4 shows that the coefficient
increases proportionally with liquid loading varying
from 6.1 to 14.6 m3/(m2 h). The reasons for this increase
are that the higher liquid loading leads to (1) the higher
k°L coefficient, which is directly proportional to the KG
coefficient in case of liquid-phase controlled mass transfer, and (2) the more AMP molecules reacting with CO2
per unit time. Although change in liquid loading can
affect the degree of effective area (av) for CO2 reaction
in the case of random packing (Perry et al., 1984), it
seems to have no effect on the effective area in the case
of gauze structured packing in this study (Bravo et al.,
1985). Therefore, the increasing KGav value in this case
is not caused by increased effective area of the packing
surface.
Figure 5. Effect of CO2 loading on overall mass transfer coefficient, KGav (AMP concentration ) 2.0 kmol/m3).
Figure 6. Effect of AMP concentration on overall mass transfer
coefficient, KGav (liquid loading ) 9.73 m3/(m2 h)).
Liquid composition also has an important effect on
the mass transfer coefficient. This effect can be divided
into (1) the effect of CO2 loading in the liquid phase,
and (2) the effect of amine (AMP) concentration. The
effect of CO2 loading is graphically shown in Figure 5,
which shows that the KGav value is strongly dependent
on the CO2 loading. The coefficient is decreased by
>80% as the loading increases from 0.15 to beyond 0.50
mol CO2/mol amine. The effect is simply caused by the
reduction of free AMP molecules, which is available for
CO2 reaction.
The effect of AMP concentration varying from 1.1 to
3.0 kmol/m3 is shown in Figure 6. Increasing AMP
concentration leads to higher KGav value. This effect
is simply due to an increase in the enhancement factor,
which is functionally related to the absorbent concentration.
Comparison with Random Packings. The values
of mass transfer coefficient and operating conditions for
the CO2-AMP system using a random and the tested
structured packings are compared in Table 2. There is
no significant difference between the test conditions for
both cases except the CO2 partial pressure. However,
reducing in the partial pressure from 9.9 kPa (structured packing) to the value for the random packing (7.8
kPa) induced a slightly higher KGav value, which
represents the higher performance of the tested structured packing. The data in Table 2 indicate that the
Ind. Eng. Chem. Res., Vol. 37, No. 2, 1998 573
Table 2. Comparison between Random and Structured Packings for CO2-AMP System
condition
Tontiwachwuthikul et al., 1989
this study
system
packing type
amine concentration, kmol/m3
CO2 loading, mol CO2/mol AMP
liquid loading, m3/(m2 h)
CO2 partial pressure, kPa
overall KGav value, kmol/(m3 h kPa)
CO2-AMP
1/2 in. ceramic Berl Saddles
2
0.15
8.76
7.8
0.11
CO2-AMP
EX type structured packing
2
0.15
9.73
9.9
0.89
Table 3. Comparison between CO2-MEA and CO2-AMP System
a
condition
Strigle, R. F., Jr., 1987
this study
system
packing type
amine concentration, kmol/m3
CO2 loading, mol CO2/mol amine
liquid loading, m3/(m2 h)
CO2 partial pressure, kPa
overall KGav value, kmol/(m3 h kPa)
CO2-MEA
3” metal Pall Rings
3
0.15
9.78
7.0
0.29a
CO2-AMP
EX type structured packing
3
0.15
9.73
9.6
1.00
Evaluated from the information summarized by Strigle (1987).
tested structured packing gives, approximately, a ninefold higher mass transfer coefficient than does the
random packing. This difference indicates that use of
structured packing can considerably improve the efficiency of CO2 absorption into hindered amine AMP
solution.
The KGav value from this study was also compared
with that for a random packing for CO2 absorption with
a conventional amine MEA, as shown in Table 3. The
tested structured packing shows almost fourfold superior performance compared with the random packing
in CO2-MEA system. In fact, the structured packing
used in this study (Sulzer type EX) can be applied to
only laboratory columns. To make the comparison more
realistic, the performance of industrial-scale structured
packing (Sulzer type BX or CY) has to be estimated and
subsequently compared. According to Sulzer packing
information (Sulzer-Chemtech’s Separation Columns for
Distillation and Absorption, 1993), the laboratory structured packing (this study) provides mass transfer
performance, which is higher than the performance for
industrial packing by about two- to fourfold. This
difference means that the KGav value for industrial
structured packing ranges from ∼0.25 to 0.50 kmol/(m3
h kPa), which is still able to compete with the KGav
value from the conventional process (CO2-MEA-random
packing). This result confirms that it is possible to use
structured packing to design an effective CO2-AMP
system, despite its inherently low absorption rate.
5. Mass Transfer Correlation for CO2-AMP
Absorption Using Structured Packing
The overall mass transfer coefficient KGav for CO2AMP system was found to be a function of the main
operating variables, that is, it increases with liquid
loading and slightly decreases with partial pressure of
CO2 over the AMP solution. Increasing the amount of
active AMP molecules, by either reducing CO2 loading
of the solution or increasing total amine concentration,
can also cause the KGav value to increase. These results
are useful for industrial applications, especially for
absorption column design. To allow the mass transfer
data to be readily utilized, an empirical KGav correlation
that includes the observed effects of the associated
operating variables should be obtained.
Conventional KGav Correlation. Compared with
the CO2-AMP system, the absorption of CO2 into
conventional amine MEA solution is a mature technology, where the mass transfer data are available and in
some cases represented in the form of correlations.
According to Kohl and Riesenfeld (1985), a mass transfer correlation for the conventional MEA system in
columns packed with random packings was proposed:
KGav ) F{L′/µL}2/3 {1 + 5.7(Req - R)Ce0.0067T-3.4PCO2}
(9)
where KGav is the overall mass transfer coefficient (lbmol/(ft3 h atm)), F is the packing correction factor, L′ is
the liquid mass flux (lb/(ft2 h)), µL is the liquid viscosity
(centipoises), Req is the CO2 loading of solution in
equilibrium with PCO2 (mol CO2/mol amine), R is the CO2
loading of solution (mol CO2/mol amine), C is the amine
concentration of the solution (kmol/m3), T is the temperature (°F), and PCO2 is the partial pressure of CO2
over solution (atm) [units are quoted directly from Kohl
and Riesenfeld (1985)].
The possibility of applying the conventional correlation to the CO2-AMP system was investigated by
calculating the KGav values on the basis of operating
conditions from this present study and subsequently
comparing the results with the experimental KGav
values. A plot of calculated KGav for different packing
correction factors (F) versus the experimental coefficient
is shown in Figure 7. The disagreement between the
two sets of data indicates that the KGav correlation for
CO2-MEA system is not suited to the absorption system
in this study. Therefore, a new correlation was developed.
Proposed Correlation. As mentioned earlier, the
mass transfer process for the CO2-AMP system is
primarily controlled by the resistance residing in the
liquid phase. Therefore, eq 5 can be rewritten as
follows:
1/KGav ≈ (H/Ik°Lav)
(10)
In this case, the overall mass transfer coefficient KGav
relates to the enhancement factor I and individual mass
transfer coefficient k°L as follows:
KGav ∝ Ik°Lav
(11)
According to Perry et al. (1984), the liquid-phase mass
transfer coefficient k°L appears to be independent of the
574 Ind. Eng. Chem. Res., Vol. 37, No. 2, 1998
Figure 7. Comparison between KGav values calculated from the
conventional correlation and those from experiments.
Figure 9. Comparison between KGav values calculated from
proposed correlation and those from experiments.
KGav ) 2.119L0.5{(Req - R)C/PCO2 - 0.0193} (15)
The predicted KGav from eq 15 was plotted against the
KGav from the experiments in Figure 9. A good agreement between the two data sets was found. It should
be noted that eq 15 was developed on the basis of
laboratory structured packing data. To apply this
correlation to the industrial-scale structured packing,
a scale-up factor involving packing geometry might be
required.
6. Conclusions
Figure 8. Relationship between (KGav/L0.5) and ratio of free amine
concentration to CO2 partial pressure, [free AMP]/PCO2.
gas flow rate and increases approximately as the 0.5
power of the liquid loading L. Furthermore, Bravo et
al. (1985) suggested that the effective packing area (av)
for gauze-type structured packing used in this study is
equal to the total geometric packing area (ap). With
these fundamentals, eq 11 can be expressed as follows:
KGav ∝ IL0.5
(12)
In case of the CO2-amine system, the enhancement
factor I could be related to CO2 partial pressure and
concentration of free amine that is available for CO2
reaction as follows (Astarita et al., 1983):
I ∝ {(Req - R)C}/PCO2
(13)
where {(Req - R)C} represents free amine concentration.
Therefore, eq 12 could be rewritten as follows:
KGav ∝ L0.5{(Req - R)C}/PCO2
(14)
To confirm this relationship, the term KGav/L0.5 was
plotted against {(Req - R)C}/PCO2 as shown in Figure 8.
The data in Figure 8 can be explained by a linear
relationship, as expected, which consequently leads to
the following final correlation:
The following principal conclusions may be drawn
from the present work:
(1) The overall mass transfer coefficient for the CO2AMP system using structured packing is a function of
main operating variables; that is, it decreases with CO2
partial pressure and CO2 loading in the liquid phase, it
increases with liquid loading, and it increases with
absorbent concentration. There is no significant effect
of gas molar flux on the overall mass transfer coefficient.
(2) The structured packing shows superior performance to random packing (1/2 in. Berl Saddles). This
superiority indicates that use of structured packing can
considerably improve the efficiency of CO2 absorption
into hindered amine AMP solution, despite its inherently low absorption rate.
(3) The outstanding performance of structured packing allows the CO2-AMP system to compete with CO2MEA absorption using random packing. Therefore, it
is possible to use structured packing in designing an
effective CO2-AMP system.
(4) The overall mass transfer coefficient for the CO2AMP system using structured packing cannot be appropriately predicted by the correlation developed for
CO2 absorption into conventional amine MEA.
(5) A new empirical mass transfer correlation that
includes the observed effects of main operating variables
(CO2 partial pressure, liquid loading, CO2 loading, and
amine concentration of the solution) was established for
CO2 absorption into hindered amine AMP solution.
Acknowledgment
The financial support of the Canada Centre for
Mineral and Energy Technology (CANMET), the Natural Sciences and Engineering Research Council of
Ind. Eng. Chem. Res., Vol. 37, No. 2, 1998 575
Canada (NSERC), Arctic Container Inc., Sulzer Brothers Ltd. (Switzerland), Saskatchewan Power Corporation, Prairie Coal Ltd., Wascana Energy Inc., and Fluor
Daniel Inc. is gratefully acknowledged.
Literature Cited
Alper, E. Reaction Mechanism and Kinetics of Aqueous Solutions
of 2-Amino-2-methyl-1-propanol and Carbon Dioxide. Ind. Eng.
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Received for review July 10, 1997
Revised manuscript received October 10, 1997
Accepted October 17, 1997X
IE970482W
X Abstract published in Advance ACS Abstracts, December
15, 1997.