Article pubs.acs.org/jced
Solubility Measurements and Saturated Liquid Properties of Ternary Systems (Methane + Decane + Octadecane) at 295 K Hossein Nourozieh, Mohammad Kariznovi, and Jalal Abedi* Department of Chemical & Petroleum Engineering, University of Calgary, Calgary, Canada ABSTRACT: Experimental vapor−liquid equilibrium (VLE) data have been measured for the ternary system (methane + decane + octadecane) at 295 K over the pressure range (1 to 8) MPa using a PVT apparatus that was designed in-house. Three different (decane + octadecane) binary mixtures were prepared, and the solubility and phase equilibria of these prepared mixtures with methane were studied. The experimental information of saturated liquid phase composition, density, and viscosity was reported at each pressure. The VLE data were correlated with the Soave−Redlich−Kwong (SRK) and Peng−Robinson (PR) equations of state (EOS's). The adjustment of binary interaction parameters and the volume translation technique has been employed to correlate the experimental compositions and densities. The adjusted binary parameters from the VLE data of binary pairs (methane + decane) and (methane + octadecane) were used to correlate the generated ternary VLE data. The calculated ternary VLE compositions were found to be in good agreement with the experimental data using the binary parameters from the VLE data of binary pairs for both EOS's. According to the results for the saturated liquid densities, more accurate predictions of the experimental data were obtained using the PR EOS than the SRK EOS.
■
INTRODUCTION Experimental measurements and thermodynamic modeling of phase equilibria and saturated phase properties for hydrocarbon mixtures are important in a wide variety of applications in petroleum and chemical engineering related processes. So far, the phase equilibrium data for different systems containing hydrocarbons have been measured with most of the data confined to simple binary systems for particular temperature and pressure conditions. Although limited vapor−liquid equilibrium (VLE) data for multicomponent systems has been reported in the literature, no experimental data for the saturated phase properties such as density and viscosity have been reported for the VLE of binary and multicomponent systems. The phase behavior of binary systems with largely different molecular sizes has already been reported in our previous studies.1−4 The experimental phase equilibrium information for the binary pair (methane + tetradecane),1 (ethane + tetradecane),2 (methane + octadecane),3 and (ethane + octadecane)4 were measured, and the solubility, density, and viscosity of saturated liquid phase were reported. The present study is an attempt to extend our experimental measurements to more complicated systems and provide a better understanding of the phase behavior of ternary systems with largely different molecular sizes. A comprehensive literature survey on the phase behavior of binary and ternary systems containing methane, decane, and octadecane has been done.5−14 The experimental conditions and the available information for the quoted systems were gathered and summarized in Table 1. As the literature survey indicates, no experimental information for © 2012 American Chemical Society
the VLE and saturated phase properties of ternary systems (methane + decane + octadecane) has been reported. Thus, it is essential to carry out experimental phase equilibrium studies, including the density and viscosity of the saturated liquid phase, for the above-mentioned ternary systems. In this study, new VLE data for the ternary system (methane + decane + octadecane) have been measured at ambient temperature over a pressure range, (1 to 8) MPa. First, three different binary mixtures of (decane + octadecane) were prepared with 0.9, 0.75, and 0.5 decane mole fractions; then, the densities of prepared binary mixtures were measured for the pressure range of (1 to 10) MPa. In the next step, the solubility of methane in three prepared binary mixtures has been reported, and the experimental phase equilibrium measurements including density and viscosity of saturated phase for the ternary system (methane + decane + octadecane) have been conducted. Finally, the experimental data obtained in our measurements were correlated using two cubic equations of state (EOS's), Soave−Redlich−Kwong (SRK)15 and Peng− Robinson (PR).16 The binary interaction parameters and the volume translation values from the experimental information on the binary pairs, (methane + decane) and (methane + octadecane), were used to predict the VLE data of the ternary system (methane + decane + octadecane). Received: May 9, 2012 Accepted: August 1, 2012 Published: August 9, 2012 2513
dx.doi.org/10.1021/je300526w | J. Chem. Eng. Data 2012, 57, 2513−2519
Journal of Chemical & Engineering Data
Article
Table 1. Available Literature Experimental Data at Temperature T and Pressure P for Binary and Ternary Systems Containing Methane, Decane, and Octadecane reference
pure light hydrocarbon
T/K
heavy hydrocarbon(s)
P/MPa
data
Binary Systems Beaudoin and Kohan5 Ng et al.6
methane
decane
248 to 423
up to 10
vapor−liquid compositions and liquid saturated molar volumes solubility
octadecane, eicosane, and docosane
303 to 473
Richon and Renon7 D’Avila et al.8
methane, ethane, propane, ethylene, and propylene methane, ethane, propane, and n-butane methane and nitrogen
298 and 323
Henry’s constant
298 to 398
Kariznovi et al.3
methane
hexadecane, octadecane, and 2,2,4,4,6,8,8-heptamethylnonane decane, 2,2,5- trimethylhexane, tertbutylbenzene, n-dodecane octadecane
low pressure low pressure 3−10
323 to 448
up to 10
saturated liquid composition, density, and viscosity
Reamer et al.9 Reamer et al.10
methane methane
butane + decane butane + decane
311 to 511 344
volumetric properties vapor−liquid compositions
Reamer et al.11
methane
butane + decane
311 to 511
up to 69 6.9 to 27.6 up to 69
Reamer et al.12 Koonce and Kobayashi13 Wiese et al.14
methane methane
butane + decane propane + decane
278 244 to 294
methane
propane + decane
278 to 511
vapor-phase solubility
Ternary Systems
■
EXPERIMENTAL SECTION Apparatus. In the previous studies,1,2 an equilibrium system for phase behavior study and physical properties measurements was described in detail. In the present work, this equipment was used for the measurements. The rocking equilibration cell has a maximum volume of about 900 cm3, which allows sufficient saturated phase volume for the measurement of physical properties, such as density and viscosity. In addition, it provides ease of phase detection and enough phase volumes for their further analyses. The equilibration and sampling cells, density measuring cell, and viscometer are placed in a temperaturecontrolled Blue M oven. The oven is equipped with a temperature controller capable of maintaining the temperature within ± 0.1 K. The Quizix pumps charge and discharge the fluids with an accuracy of ± 0.001 cm3. An Anton Paar vibrating tube density measuring cell equipped with a DMA HPM external high-pressure unit is calibrated using nitrogen and water. The data for the densities of nitrogen and water at specific temperatures and pressures were taken from the National Institute of Standards and Technology (NIST)17 database. The measuring cell is equipped with a U-shaped hastelloy tube into which the fluid is transferred. The tube is electronically vibrated at its characteristic frequency, and depending on the density of the fluid, the characteristic frequency changes. By precise determination of the characteristic frequency and a mathematical conversion, the density of the fluid will be calculated. The Cambridge viscometer (ViscoPro 2000), which is a flowthrough viscosity sensor, is capable of measuring the viscosity in the range of (0.25 to 20 000) mPa·s and pressure up to 14 MPa. The piston-style viscometer uses two magnetic coils within a stainless steel sensor and a magnetic piston inside the pipe line. The piston is forced magnetically back and forth within a predetermined distance. The fluid sample surrounds the piston, and depending on the viscosity, the piston’s round trip travel time is measured at constant force exerted. The time required to complete a two-way cycle is an accurate measure of viscosity. The viscometer is equipped with sensor SPC-372, and
up to 35 0.14 to 6.9 up to 28
volumetric behavior and vapor−liquid compositions vapor−liquid compositions k-values and vapor−liquid compositions vapor−liquid compositions and liquid saturated molar volumes
it is factory calibrated. The density measuring cell and viscometer are installed in series to improve the phase detection. Their in-line measurements provide data of higher accuracy than sending very small samples to the viscometer and density measuring cell separately. Materials and Sample Preparation. Methane was supplied by Praxair with a purity of 0.9997 mole fraction. Decane and octadecane were obtained from Alfa Aesar Company. All of the chemicals were used without any further purification. Table 2 summarizes the chemical sample specifications. Table 2. Chemical Sample Specifications chemical name
source
CAS no.
initial purity
74-82-8
decane
Praxair (3.7 ultra high purity) Alfa Aesar
octadecane
Alfa Aesar
593-45-3
0.9997 mole fraction 0.99 mass fraction 0.99 mass fraction
methane
124-18-5
purification method none none none
Three different binary mixtures of (decane + octadecane) were prepared. For the preparation of samples, a Sartorius balance (model: LP4200S) with the measurement uncertainty of ± 0.01 g was used. The binary mixtures were prepared in three decane mole fractions (0.50, 0.75, and 0.90) to cover entire composition range. The prepared mixtures had a weight of at least 1000 g; therefore, the uncertainty introduced by sample preparation for molar composition was less than ± 0.0001 for all compositions. The density of three prepared binary mixtures was measured at ambient temperature using vibrating tube density measuring cell and is given in Table 3. The uncertainties of density measurements were 0.1 kg·m−3. To compare the binary mixtures, their densities and that of pure decane are listed in the last column of Table 3, which were taken from the NIST17 Chemistry WebBook. The pure octadecane was solid at 295 K over the pressure range, (1 to 10) MPa. As the results in Table 3 indicated, the binary mixture 2514
dx.doi.org/10.1021/je300526w | J. Chem. Eng. Data 2012, 57, 2513−2519
Journal of Chemical & Engineering Data
Article
Table 3. Measured Densities, ρm, of Binary Mixtures {Decane (1) + Octadecane (2)} at Constant Temperature and Different Pressures Pa
density and volume of the evolved gas at atmospheric conditions. The uncertainty of 0.002 in the measurements of the mole fraction for the liquid phase was estimated. The composition of gas phase was also measured with gas chromatography (GC). The GC results indicated pure methane in the vapor phase for all experiments.
ρm/(kg·m−3) P/MPa
x1 = 0.50 at 295.1 K
x1 = 0.75 at 295.2 K
x1 = 0.90 at 295.8 K
x1 = 1 at 295.0 K (NIST Data)b
1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
759.7 760.4 761.1 761.7 762.4 763.1 763.7 764.4 765.1 765.8
745.7 746.4 747.1 747.9 748.6 749.3 750.0 750.7 751.4 752.1
733.9 734.7 735.4 736.2 736.9 737.6 738.4 739.1 739.9 740.6
729.69 730.47 731.25 732.02 732.78 733.53 734.28 735.02 735.75 736.47
■
RESULTS AND DISCUSSION Experimental Results. This work presents the isothermal VLE data for the systems (methane + decane + octadecane). Experiments were performed with three prepared binary mixtures at 295 K for eight different pressures from (1 to 8) MPa. During the experiments, methane-saturated liquid composition, density, and viscosity were measured. The experimental ternary data are collected in Table 4. The equilibrium vapor phases for all experiments were virtually pure methane; the decane and octadecane compositions were too low in gas phase for accurate measurement. As the results in Table 4 indicate, the methane composition in the saturated liquid phase increased with the pressure for all three prepared mixtures. The saturated liquid density and viscosity reduced with the pressure due to the higher solubility of methane. This effect is more pronounced in the case of
a Uncertainties u; u(T) = 0.1 K, u(P) = 0.01 MPa, and the combined expanded uncertainties uc; uc(ρ) = 0.1 kg·m−3. bDensity data for pure decane were taken from the NIST17 Chemistry WebBook.
became heavier with the decane concentration reduced from (1 to 0.5) mole fraction. Procedure. The experimental procedure used in this study is similar to our previous studies,1−4 and it is briefly discussed. Prior to each experiment, the entire system was thoroughly cleaned to remove any contaminant; the cells and lines were then successively evacuated and flushed with helium and methane. After cleaning, the prepared mixture of (decane + octadecane) was fed into the equilibration cell using the two Quizix pumps. Methane was then charged into the cell. To measure the solubility at a specific temperature and pressure, the experimental pressure and temperature were fixed. The pressure in the equilibrium cell was kept constant using the Quizix pump. The equilibration cell was rocked to achieve effective mixing and to reach equilibrium conditions for the ternary system. During the mixing period, the volume of mixture to keep a constant pressure in the equilibration cell was recorded. When there was no change in the volume, equilibrium was achieved. Thus, the volume change on mixing is the criteria for equilibrium. Prior to the discharge of the equilibrium fluids, the equilibration cell was first kept in an upright position (vertical position) for a few hours to obtain single bulk volume of each phase vertically segregated in the order of phase density. The equilibrium fluids were then discharged from the top of equilibration cell through the density measuring cell and viscometer, while maintaining a constant temperature and pressure. The phase samples were collected with steady readings of the density measuring cell and viscometer; any change in density and viscosity indicated a passage of a phase boundary through the measuring instruments. Vapor and liquid phases were transferred into sampling cells 1 to 3, and the last sampling cell was used to purge the phase boundary portion and clean the transition between the phases. Saturated samples could be collected through the sampling port for compositional analysis or further studies. To measure the solubility of the saturated liquid, the collected samples were flashed at atmospheric pressure. The volume of the evolved gas was measured by the Chandler Engineering Gasometer (model 2331) with a 0.2 % accuracy of the reading. The solubility was then calculated having the
Table 4. Experimental Vapor−Liquid Equilibrium Data of the Systems {Methane (1) + Decane (2) + Octadecane (3)} for Temperature T, Pressure P, Saturated Liquid Density ρs, Saturated Liquid Viscosity μs, and Mole Fraction of Components in the Saturated Liquid Phase xa T/K
P/MPa
102 x1
102 x2
ρs
μs
kg·m−3
mPa·s
0.9 mole fraction Decane + 0.1 mole fraction Octadecane 0.97 5.3 85.2 728 2.06 10.6 80.4 722 2.97 14.7 76.7 718 4.01 18.6 73.3 713 4.94 22.1 70.1 707 6.14 26.6 66.0 700 7.11 29.9 63.1 696 8.05 32.2 61.0 692 0.75 mole fraction Decane + 0.25 mole fraction Octadecane 294.7 0.94 5.5 70.9 739 294.8 2.04 10.7 67.0 734 295.0 3.04 15.0 63.8 729 295.1 4.01 18.8 60.9 725 294.4 4.96 22.7 58.0 721 294.6 5.96 26.2 55.4 716 294.7 6.90 29.1 53.2 712 294.9 8.01 32.5 50.6 707 0.5 mole fraction Decane + 0.5 mole fraction Octadecane 294.7 0.99 5.9 47.0 753 294.8 2.02 11.1 44.4 749 295.7 3.03 15.5 42.2 744 295.9 3.99 19.0 40.5 740 295.7 5.10 23.7 38.1 735 295.7 6.01 26.7 36.6 732 294.9 6.94 29.6 35.2 729 295.0 7.93 32.7 33.7 725 295.7 295.7 295.0 295.1 295.8 295.8 295.5 295.6
1.05 0.98 0.92 0.86 0.81 0.73 0.69 0.64 1.65 1.52 1.42 1.31 1.21 1.09 0.98 0.85 2.16 2.03 1.88 1.72 1.59 1.43 1.31 1.22
a Uncertainties u; u(T) = 0.1 K, u(P) = 0.01 MPa, u(x) = 0.002, and the combined expanded uncertainties uc; uc(ρs) = 1 kg·m−3, and uc(μs) = 0.05 μs.
2515
dx.doi.org/10.1021/je300526w | J. Chem. Eng. Data 2012, 57, 2513−2519
Journal of Chemical & Engineering Data
Article
version of PR EOS18 for hydrocarbons heavier than decane was used in this study. The constant characteristic of each substance for this EOS was obtained as,
saturated liquid viscosities as plotted in Figure 1. As depicted in the figure, the saturated liquid viscosity reduced to almost 50 %
⎛ ⎡ α(T ) = ⎜⎜1 + κ ⎢1 − ⎣⎢ ⎝
T Tc
⎤⎞ ⎥⎟⎟ ⎥⎦⎠
2
(1)
κ = 0.379642 + 1.48503ω − 0.164423ω 2 + 0.016666ω3 (2)
To obtain reliable results for the whole composition range and the pressure range, the so-called interaction parameters, δij, for binary pairs within the mixture were optimized for each EOS. To improve the volumetric results, a volume translation according to Peneloux et al.19 was considered in both EOS's. The properties of the pure compounds used in this work are summarized in Table 5. The correlation of the ternary systems was carried out with the interaction parameters of the binary subsystems. Thus, the literature data (reported by Beaudoin and Kohn5) for the binary system (methane + decane) at 298.15 K were fitted with the above-mentioned EOS's by the adjustment of the binary interaction parameter as well as the decane volume translation value. The best set of the parameters that minimize the deviations between the calculated and the experimentally determined composition, as well as the density of saturated liquid, were determined. The average absolute deviations (AAD) for composition and density were calculated as,
Figure 1. Saturated liquid viscosities μs for ternary systems {methane (1) + decane (2) + octadecane (3)}; P, pressure; x, mole fraction. Experimental data of this study at 295 K; ■, (x2/x3) = 1; ⧫, (x2/x3) = 3; ▲, (x2/x3) = 9.
of the initial values at the highest pressure which corresponds to the highest solubility of methane. Generally speaking, the pressure affects the density and viscosity of the liquid in two ways. First, at a constant temperature, an increase in pressure results in an increase in the liquid density and viscosity. Second, the density and viscosity of the liquid decreased with the increasing methane solubility at higher pressures. As the first factor had a small effect on the liquid density and viscosity, the other factor can result in significant changes in the density and viscosity of the liquid phase. Comparing the solubility of methane in three different mixtures (Table 4) revealed that methane composition in the saturated liquid phase was almost the same for three binary systems considering isobaric data. This behavior was observed when methane composition was reported in mole fraction. It can be further investigated by converting methane composition into weight fraction instead of mole fraction. In this case, methane composition in the saturated liquid phase decreased at constant pressure as the mixture became heavier {(x2/x3) decreased from 9 to 1}. This behavior was expected because, as the liquid phase became heavier, the solubility of methane was decreased at constant temperature and pressure. Thus, during this study, the composition was reported in both mole and weight fractions in all figures to distinguish methane composition in three ternary systems. Correlation of VLE Data. The generated VLE data for the ternary systems have been estimated by using SRK and PR EOS's coupled with the classical mixing rule. The modified
AAD(x) =
AAD(ρ) =
xcalcd − xexptl ⎛ 100 ⎞ ⎜ ⎟ ∑ ⎝ N ⎠ xexptl
(3)
ρcalcd − ρexptl ⎛ 100 ⎞ ⎜ ⎟ ∑ ⎝ N ⎠ ρ
(4)
exptl
As no phase equilibrium experimental data has been reported for (methane + octadecane) system at 295 K in the literature, the binary interaction parameter and volume translation value for this system were evaluated from the extrapolation of the adjusted parameters reported by Kariznovi et al.3 Thus, the temperature-dependent binary interaction parameter and volume translation value presented in the study of Kariznovi et al.3 were fitted with second-degree polynomials. The temperature dependency of parameters suggests that the temperature dependency terms of the EOS's coupled with van der Waals mixing rule alone were not sufficient in describing the temperature influence.1,21 In addition, the temperature-dependent parameter was selected to have a better investigation of the nonideal behavior in binary hydrocarbon systems containing hydrocarbons with greatly different molecular sizes.
Table 5. Thermodynamic Properties (Molecular Weight, MW, Boiling Point, Tb, Critical Temperature, Tc, Critical Pressure, Pc, Critical Volume, Vc, and Acentric Factor, ω) of Components20 Vc
MW component
g·mol−1
Tb/K
Tc/K
Pc/MPa
cm3·mol−1
ω
methane decane octadecane
16.043 142.285 254.5
111.66 447.30 589.86
190.58 618.45 745.26
4.604 2.123 1.214
99.3 603.1 1070.0
0.011 0.484 0.795
2516
dx.doi.org/10.1021/je300526w | J. Chem. Eng. Data 2012, 57, 2513−2519
Journal of Chemical & Engineering Data
Article
Table 6. Volume Translation Valuesa, Vs, Binary Interaction Parameters, δij, and Average Absolute Deviations, AAD, of Various Systems; Methane (1), Decane (2), Octadecane (3); Saturated Liquid Composition, x, and Saturated Liquid Density, ρ
Figure 2 illustrates the temperature-dependent binary interaction parameter and volume translation value for
parameter
methane + decane
δij Vs AAD(x) AAD(ρ)
δ12 = 0.0486 0.1981 2.12 0.420
δij Vs AAD(x) AAD(ρ)
δ12 = 0.0528 0.0748 1.80 0.039
methane + octadecane SRK EOS δ13 = 0.0504 0.3398
PR EOS δ13 = 0.0472 0.2459
methane + decane + octadecane δ23 = 0.0304b c 3.59 0.503 δ23 = 0.0274b c 3.43 0.236
a
Volume translation values were applied to decane and octadecane components. bBinary interaction parameters, δ12 and δ13, were fixed at the values obtained from binary systems for each EOS. cVolume translation values of binary systems were applied for the ternary system.
Figure 2. Binary interaction parameter δij and volume translated value Vs for the methane + octadecane system;3 T, temperature. ○, △, PR EOS; □, ∗, SRK EOS: ○, □, adjusted binary interaction parameters; △, ∗, adjusted volume translation values; ---, extrapolated line from second-degree fitted polynomials; , fitted second-degree polynomials.
(methane + octadecane) binary systems obtained with SRK and PR EOS's. The dots are the adjusted parameters reported by Kariznovi et al.3 at four different temperatures. We have correlated these parameters as a function of temperature with the second-degree polynomials which were also presented as solid lines in Figure 2. The extrapolation of adjusted parameters into 295 K was also shown as dashed lines. The remaining adjustment parameters for the ternary system (methane + decane + octadecane) are the interaction parameters between decane and octadecane. To obtain this parameter, experimental information about the binary system (decane + octadecane) is required. As no experimental data for the binary system (decane + octadecane) were reported in the literature, this parameter was adjusted using the generated experimental phase equilibrium composition and density data in this study (the generated data for ternary system {methane + decane + octadecane}). Thus, the binary interaction parameters and volume translation values for the binary pairs (methane + decane) and (methane + octadecane) were fixed from the reported binary VLE data, and the interaction parameter for (decane + octadecane) system was adjusted using generated ternary data. The binary parameters of the EOS models along with the average deviations between calculated and measured values (AADs) are shown in Table 6. On the basis of AADs, the best results for the correlations of the experimental data were achieved with the PR EOS. The correlated experimental data, saturated liquid compositions and densities, using SRK EOS and PR EOS for the investigated systems (methane + decane + octadecane) are shown in Figures 3 to 6. In these plots, the lines denote the calculation results by EOS's, and the dots show the experimental data. Figures 3 and 5 show methane compositions in saturated liquid phases both in mole (dash lines) and weight (solid lines) fractions, and Figures 4 and 6 demonstrate the saturated phase densities. The literature experimental data for (methane + decane) systems at similar temperatures and pressures were also shown in Figures 3 to 6.
Figure 3. Phase equilibria for ternary systems {methane (1) + decane (2) + octadecane (3)}; P, pressure; w1, weight fraction of methane in saturated liquid phase; x1, mole fraction of methane in saturated liquid phase. ■, ⧫, ▲, □, ◊, △, experimental data of this study at 295 K; ●, ○, literature experimental data5 for the methane + decane system (x3 = 0) at 298.15 K: ■, ⧫, ▲, experimental data reported in weight fraction; □, ◊, △, experimental data reported in mole fraction; ■, □, (x2/x3) = 1; ⧫, ◊, (x2/x3) = 3; ▲, △, (x2/x3) = 9; ●, ○, x3 = 0; , − − −, SRK EOS.
A comparison of the experimental data from this study for ternary systems and the literature data5 for (methane + decane) binary systems (Figures 4 and 6) indicated that the solubility data were consistent. That is, methane composition (reported in weight fraction) in saturated liquid phase decreases from pure decane system to a 0.5 mole fraction decane (heavier) system considering isobaric data at ambient temperature. This behavior with opposite trend was also observed when methane composition was reported in mole fraction. The saturated liquid density data confirmed the consistency of the data from this study for ternary systems with the data of Beaudoin and Kohn5 for the binary system. As one can observe from Figures 3 to 6, both EOS's predicted the composition of methane in liquid phase well over the studied pressure range. For the saturated liquid densities, 2517
dx.doi.org/10.1021/je300526w | J. Chem. Eng. Data 2012, 57, 2513−2519
Journal of Chemical & Engineering Data
Article
Figure 4. Saturated liquid densities ρs for ternary systems {methane (1) + decane (2) + octadecane (3)}; P, pressure; x, mole fraction. ■, ⧫, ▲, experimental data of this study at 295 K; , SRK EOS; ■, (x2/ x3) = 1; ⧫, (x2/x3) = 3; ▲, (x2/x3) = 9; ●, literature experimental data5 for the methane + decane system (x3 = 0) at 298.15 K.
Figure 6. Saturated liquid densities ρs for ternary systems {methane (1) + decane (2) + octadecane (3)}; P, pressure; x, mole fraction. ■, ⧫, ▲, experimental data of this study at 295 K; , PR EOS; ■, (x2/ x3) = 1; ⧫, (x2/x3) = 3; ▲, (x2/x3) = 9; ●, literature experimental data5 for the methane + decane system (x3 = 0) at 298.15 K.
Figure 5. Phase equilibria for ternary systems {methane (1) + decane (2) + octadecane (3)}; P, pressure; w1, weight fraction of methane in saturated liquid phase; x1, mole fraction of methane in saturated liquid phase. ■, ⧫, ▲, □, ◊, △, experimental data of this study at 295 K; ●, ○, literature experimental data5 for the methane + decane system (x3 = 0) at 298.15 K; ■, ⧫, ▲, experimental data reported in weight fraction; □, ◊, △, experimental data reported in mole fraction; ■, □, (x2/x3) = 1; ⧫, ◊, (x2/x3) = 3; ▲, △, (x2/x3) = 9; ●, ○, x3 = 0; , − − −, PR EOS.
Figure 7. Calculated deviations of generated experimental saturated liquid compositions xexp from values xcal obtained with the SRK EOS and PR EOS for ternary systems {methane (1) + decane (2) + octadecane (3)} at 295 K. □ ,◊, △, ○, SRK EOS; ■, ⧫, ▲, ●, PR EOS; □, ■, (x2/x3) = 1; ◊, ⧫, (x2/x3) = 3; △, ▲, (x2/x3) = 9; ○, ●, literature data5 for the methane + decane system (x3 = 0) at 298.15 K.
■
CONCLUSION Experimental VLE data have been reported for the ternary system (methane + decane + octadecane) at 295 K over the pressure range (1 to 8) MPa. The phase equilibrium data of saturated liquid composition, density, and viscosity were measured at each pressure. The experimental results indicated that methane composition in saturated liquid phase increased with the pressure for all three prepared mixtures. The saturated liquid density and viscosity reduced with the pressure due the higher solubility of methane. This effect was more pronounced in the case of saturated liquid viscosities. Comparing the solubility of methane in three different mixtures revealed that methane composition in saturated liquid phase increased as the mixture became heavier considering isobaric VLE data. This behavior was observed when methane composition was reported in mole fraction. However, an opposite trend was
the PR EOS resulted in better predictions than SRK EOS. However, neither the SRK EOS nor PR EOS was able to describe accurately the saturated liquid densities for mixtures (0.5 mole fraction decane + 0.5 mole fraction octadecane). For a better comparison of generated data and modeling results, the deviations between the experimental and the modeling results for composition and density of saturated liquid phase were also calculated and presented in Figures 7 and 8. Although the predicted results for compositions by two EOS's seem to be same (Figures 3 and 5), a comparison based on the deviation plots demonstrates that the PR EOS provides lower average deviations of compositions. From Figure 8, the deviations for saturated liquid densities, we conclude that the calculated values of densities with the PR EOS were much better than those of the SRK EOS. 2518
dx.doi.org/10.1021/je300526w | J. Chem. Eng. Data 2012, 57, 2513−2519
Journal of Chemical & Engineering Data
Article
(2) Kariznovi, M.; Nourozieh, H.; Abedi, J. Measurement and Modeling of Liquid Saturated Properties (Solubility, Density, and Viscosity) of (Ethane + n-Tetradecane) Binary Systems. J. Chem. Eng. Data 2011, 56, 3669−3672. (3) Kariznovi, M.; Nourozieh, H.; Abedi, J. Measurement and Equation of State Prediction of Vapor−Liquid Equilibrium and Physical Properties for the System Methane + n-Octadecane. Fluid Phase Equilib. 2012, 314, 102−106. (4) Nourozieh, H.; Kariznovi, M.; Abedi, J. Experimental Measurement and Equation of State Modeling of Liquid Saturated Properties (Solubility, Density, and Viscosity) of (Ethane + n-Octadecane) Binary Systems. J. Chem. Eng. Data 2012, 57, 137−141. (5) Beaudoin, J. M.; Kohn, J. P. Multiphase and Volumetric Equilibria of the Methane-n-Decane Binary System at Temperatures between −36 and 150 °C. J. Chem. Eng. Data 1967, 12, 189−191. (6) Ng, S.; Harries, H. G.; Prausnitz, J. M. Henry’s Constants for Methane, Ethane, Ethylene, Propane, and Propylene in Octadecane, Eicosane, and Docosane. J. Chem. Eng. Data 1969, 14, 482−483. (7) Richon, D.; Renon, H. Infinite Dilution Henry’s Constants of Light Hydrocarbons in n-Hexadecane, n-Octadecane, and 2,2,4,4,6,8,8Heptamethylnonane by Inert Gas Stripping. J. Chem. Eng. Data 1980, 25, 59−60. (8) D’Avila, S. G.; Kaul, B. K.; Prausnitz, J. M. Solubilities of Heavy Hydrocarbons in Compressed Methane and Nitrogen. J. Chem. Eng. Data 1976, 21, 488−491. (9) Reamer, H. H.; Sage, B. H.; Lacey, W. N. Phase Equilibria in Hydrocarbon Systems - Methane-n-Butane-Decane System. Ind. Eng. Chem. 1947, 39, 77−82. (10) Reamer, H. H.; Fiskin, J. M.; Sage, B. H. Phase Equilibria in Hydrocarbon Systems. Ind. Eng. Chem. 1949, 41, 2871−2875. (11) Reamer, H. H.; Sage, B. H.; Lacey, W. N. Phase Equilibria in Hydrocarbon Systems. Volumetric and Phase Behavior of the Methane-n-Butane-Decane System. Ind. Eng. Chem. 1951, 43, 1436− 1444. (12) Reamer, H. H.; Sage, B. H.; Lacey, W. N. Phase Equilibria in Hydrocarbon Systems - Methane-n-Butane-Decane system at 40 °F. Ind. Eng. Chem. 1952, 44, 1671−1675. (13) Koonce, K. T.; Kobayashi, R. Vapor-Liquid Equilibrium Coefficients Determined by Gas-Liquid Partition Chromatography: Systems Methane-Propane-n-Decane and Methane-Propane-n-Heptane. J. Chem. Eng. Data 1964, 9, 494−501. (14) Wiese, H. C.; Reamer, H. H.; Sage, B. H. Phase Equilibriums in Hydrocarbon Systems. Phase Behavior in the Methane-propane-ndecane System. J. Chem. Eng. Data 1970, 15, 75−82. (15) Soave, G. Equilibrium Constants from a Modified RedlichKwong Equation of State. Chem. Eng. Sci. 1972, 27, 1197−1203. (16) Peng, D. Y.; Robinson, D. B. A New Two-Constant Equation of State. Ind. Eng. Chem. Fundam. 1976, 15, 59−64. (17) Thermophysical properties of fluid systems; National Institute of Standards and Technology: Gaithersburg, MD; http://webbook.nist. gov/chemistry/fluid. (18) Robinson, D. B.; Peng, D. Y. The Characterization of the Heptanes and Heavier Fractions for the GPA Peng-Robinson Programs, Research Report RR-28; Gas Processors Association: Tulsa, OK, March 1978. (19) Peneloux, A.; Rauzy, E.; Freze, R. A consistent correction for Redlich-Kwong-Soave volumes. Fluid Phase Equilib. 1982, 8, 7−23. (20) Yaws, C. L. Chemical Properties Handbook; McGraw-Hill: New York, 1999. (21) Flöter, E.; de Loos, T. W.; de Swaan Arons, J. Improved Modeling of the Phase Behavior of Asymmetric Hydrocarbon Mixtures with the Peng−Robinson Equation of State Using a Different Temperature Dependency of the Parameter a. Ind. Eng. Chem. Res. 1998, 37, 1651−1662.
Figure 8. Calculated deviations of generated experimental saturated liquid densities ρexp from values ρcal obtained with the SRK EOS and PR EOS for ternary systems {methane (1) + decane (2) + octadecane (3)} at 295 K. □, ◊, △, ○, SRK EOS; ■, ⧫, ▲, ●, PR EOS; □, ■, (x2/x3) = 1; ◊, ⧫, (x2/x3) = 3; △, ▲, (x2/x3) = 9; ○, ●, literature data5 for the methane + decane system (x3 = 0) at 298.15 K.
observed when methane composition was presented in weight fraction. The ternary experimental compositional data are reasonably well-correlated with two cubic EOS's using the binary parameters fitted with the VLE data at isothermal conditions {(methane + decane) binary system} and the extrapolation of adjusted parameters {(methane + octadecane) binary system}. The AADs for (methane + decane) binary system were 2.12 and 1.8 for SRK and PR EOS's, respectively. For ternary system, AADs were higher, 3.59 and 3.43 for SRK and PR EOS's, respectively. Neither SRK EOS nor PR EOS was able to accurately describe the saturated liquid densities of mixtures with a higher concentration of octadecane (0.5 mole fraction decane + 0.5 mole fraction octadecane).
■
AUTHOR INFORMATION
Corresponding Author
*Address: 2500 University Dr., NW, Calgary, Alberta, T2N 1N4 Canada. E-mail:
[email protected]. Tel.: 403-220-5594. Funding
The authors wish to express their appreciation for the financial support of all member companies of the SHARP (Solvent/ Heat-Assisted Recovery Processes) Research consortium: Alberta Innovates Energy and Environment Solutions, Chevron Energy Technology Co., Computer Modeling Group Limited, ConocoPhillips Canada, Devon Canada Co., Foundation CMG, Husky Energy, Japan Canada Oil Sands Limited, MacKay Operating Co., Nexen Inc., Laricina Energy Ltd., National Sciences and Engineering Research Council of Canada (NSERC-CRD), OSUM Oil Sands Co., Penn West Energy, Statoil Canada Ltd., Suncor Energy, and Total E&P Canada. Notes
The authors declare no competing financial interest.
■
REFERENCES
(1) Nourozieh, H.; Kariznovi, M.; Abedi, J. Vapor−Liquid Equilibrium Measurement and Thermodynamic Modeling of Binary Systems (Methane + n-Tetradecane). Fluid Phase Equilib. 2012, 318, 96−101. 2519
dx.doi.org/10.1021/je300526w | J. Chem. Eng. Data 2012, 57, 2513−2519
