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SECTION 23

Physical Properties This section contains a number of charts, correlations, and calculation procedures to be used for predicting physical properties of hydrocarbons and components found with them. Fig. 23-1 shows the nomenclature used in this section.

ponents. Immediately following is a detailed list of references and footnoted explanation for the values in Fig. 23-2. Physical properties for eighteen selected compounds can be found in GPA Standard 2145, "Table of Physical Constants of Paraffin Hydrocarbons and Other Components of Natural Gas."

Fig. 23-2 is a table containing frequently used physical properties for a number of hydrocarbons and other selected com-

FIG. 23-1 Nomenclature B = second virial coefficient for a gas mixture, [kPa (abs)]-1 B′ = mole fraction H2S in sour gas stream, Eq 23-6 Bii = second virial coefficient for component i Bij = second cross virial coefficient for components i and j bi1/2 = summation factor for component i CABP = cubic average boiling point, °C d = density, g/cc G = relative density (gas density) Gi = relative density (gas gravity) of ideal gas, MW/MWa Gid = molecular mass ratio of component i in mixture i Hv = gross heating value per unit volume of ideal gas, MJ/m3 Kw = Watson characterization factor, Fig. 23-12 k = thermal conductivity, W/(m • °C) ka = thermal conductivity at one atmosphere, W/(m • °C) M = mass fraction m = mass, kg MW = molecular mass, g mole MABP = molal average boiling point, °C or K MeABP = Mean average boiling point, °C or K n = number of moles (mass/mole weight) P = pressure, kPa (abs) Pc′ = pseudocritical pressure adjusted for acid gas composition, kPa (abs) Pvp = vapor pressure at a reduced temperature of 0.7 Pwo = vapor pressure of water, 7.3811 kPa (abs) at 40°C R = gas constant, 8.3145 [kPa (abs) • m3]/(K • kg mole) for all gases (see Section 1 for R in other units) S = relative density at 15°/15°C T = absolute temperature, K t = ASTM D-86 distillation temperature, °C or K, Eq 23-11 Tc′ = pseudocritical temperature adjusted for acid gas composition, K V = volume, m3 VABP = volumetric average boiling point, °C

23-1

W = mass, kg WABP = weight average boiling point, °C yi = mole fraction of component i from analysis on dry basis, Eq 23-37 x = mole fraction in liquid phase yw i = mole fraction of component i adjusted for water content y = mole fraction in gas phase Z = compressibility factor Greek ε = pseudocritical temperature adjustment factor, Eq 23-6 θ = MeABP/Tpc ρ = density, kg/m3 µ = viscosity at operating temperature and pressure, centipoise µA = viscosity at 101.325 kPa (abs) (1 atm) and operating temperature, centipoise ξ = factor defined by Eq 23-20 σ = surface tension, dynes/cm ω = acentric factor η = kinematic viscosity, centistokes Subscripts a = air b = boiling c = critical i = component i L = liquid m = mixture pc = pseudocritical r = reduced state V = vapor v = volume w = water Superscripts id = ideal gas w = water o = reference state

FIG. 23-2 Physical Constants NOTE: Numbers in this table do not have accuracies greater than 1 part in 1000; in some cases extra digits have been added to calculated values to achieve internal consistency or to permit recalculation of experimental values.

A.

See Note No.

PHYSICAL CONSTANTS B.

C.

*See the Table of Notes and References D.

Refractive index, nD 15˚C

Pressure, kPa(abs)

Temperature, K

Volume, m3/kg

Number

C H4 C2 H 6 C3 H 8 C4 H 10 C4 H 10

16.043 30.070 44.097 58.123 58.123

-161.51 -88.59 -42.07 -11.79 -0.51

(35000)* (6000)* 1369.8 530.89 379.61

-182.45* -182.79* -187.62" -159.59 -138.35

1.00040* 1.21403* 1.29558* 1.3251* 1.33631*

4599. 4880. 4240. 3640. 3784.

190.56 305.41 369.77 407.82 425.10

0.00617 0.00489 0.00454 0.00446 0.00439

1 2 3 4 5

6 7 8

Isopentane n-Pentane Neopentane

C5 H 12 C5 H 12 C5 H 12

72.150 72.150 72.150

27.83 36.05 9.50

151.31 114.70 270.0

-159.89 -129.71 -16.58

1.35658 1.36024 1.345*

3381. 3365. 3199.

460.35 469.65 433.71

0.00427 0.00434 0.00420

6 7 8

9 10 11 12 13

n-Hexane 2-Methylpentane 3-Methylpentane Neohexane 2,3-Dimethylbutane

C6 C6 C6 C6 C6

H 14 H 14 H 14 H 14 H 14

86.177 86.177 86.177 86.177 86.177

68.72 60.24 63.26 49.72 57.96

37.297 50.68 45.73 73.41 55.34

-95.31 -153.67 -162.89 -99.825 -128.53

1.37746 1.37417 1.37918 1.37157 1.37759

3030. 3010. 3120. 3080. 3130.

506.4 497.46 504.4 488.66 499.86

0.00429 0.00426 0.00426 0.00417 0.00415

9 10 11 12 13

14 15 16 17 18 19 20 21

n-Heptane 2-Methylhexane 3-Methylhexane 3-Ethylpentane 2,2-Dimethylpentane 2,4-Dimethylpentane 3,3-Dimethylpentane Triptane

C 7 H 16 C 7 H 16 C 7 H 16 C 7 H 16 C 7 H 16 C 7 H 16 C 7 H 16 C 7 H 16

100.204 100.204 100.204 100.204 100.204 100.204 100.204 100.204

98.37 90.03 91.85 93.47 79.17 80.47 86.04 80.86

12.342 17.226 16.155 15.265 26.32 24.85 20.94 25.41

-90.55 -118.26 — -118.58 -123.78 -119.21 -134.44 -24.56

1.39017 1.38743 1.39119 1.39594 1.38475 1.38408 1.39342 1.39196

2740. 2730. 2810. 2890. 2770. 2740. 2950. 2950.

539.2 530.06 535.16 540.46 520.36 519.66 536.26 531.06

0.00426 0.00420 0.00403 0.00415 0.00415 0.00417 0.00413 0.00397

14 15 16 17 18 19 20 21

22 23 24 25 26 27 28 29 30

n-Octane Diisobutyl Isooctane n-Nonane n-Decane Cyclopentane Methylcyclopentane Cyclohexane Methylcyclohexane

C8 H 18 C8 H 18 C8 H 18 C9 H 20 C10 H 22 C5 H 10 C6 H 12 C6 H 12 C7 H 14

114.231 114.231 114.231 128.258 142.285 70.134 84.161 84.161 98.188

125.65 109.08 99.21 150.78 174.11 49.22 71.83 80.78 100.94

4.146 8.417 12.966 1.358 0.4814 73.99 33.75 24.64 12.211

-56.76 -91.160 -107.35 -53.48 -29.63 -93.827 -142.43 6.550 -126.59

1.39981 1.39488 1.39392 1.40773 1.41411 1.40927 1.41240 1.42892 1.42566

2490. 2490. 2570. 2280. 2100. 4508. 3784. 4073. 3471.

568.4 549.96 543.86 594.7 617.7 511.6 532.75 553.5 572.15

0.00420 0.00422 0.00410 0.00433 0.00439 0.00371 0.00379 0.00366 0.00375

22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

Ethene(Ethylene) Propene(Propylene) 1-Butene(Butylene) cis-2-Butene trans-2-Butene Isobutene 1-Pentene 1,2-Butadiene 1,3-Butadiene Isoprene

C2 C3 C4 C4 C4 C4 C5 C4 C4 C5

H4 H6 H8 H8 H8 H8 H 10 H6 H6 H8

28.054 42.081 56.108 56.108 56.108 56.108 70.134 54.092 54.092 68.119

-103.73 -47.68 -6.23 3.72 0.88 -6.91 29.95 10.84 -4.41 34.05

-169.15* -185.25* -185.35* -138.90 -105.54 -140.34 -165.21 -136.19 -108.89 -145.95

(1.241)* 1.313* 1.351* 1.368* 1.359* 1.358* 1.3746 — — 1.4253

5040. 4665. 4043. 4243. 3964. 4000. 3513. (4502) 4277. (3856)

282.34 365.55 419.92 435.54 428.59 417.86 464.74 (444)* 425. (484)

0.00466 0.00448 0.00426 0.00417 0.00424 0.00425 0.00421 (0.0043)* 0.00407 (0.0041)*

31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49

Acetylene Benzene Toluene Ethylbenzene o-Xylene m-Xylene p-Xlyene Styrene Isopropylbenzene

C2 C6 C7 C8 C8 C8 C8 C8 C9

H2 H6 H8 H10 H10 H10 H10 H8 H 12

26.038 78.114 92.141 106.167 106.167 106.167 106.167 104.152 120.194

-84.01* 80.07 110.60 136.17 144.39 139.09 138.32 145.23 152.38

— 24.38 7.895 2.873 2.051 2.528 2.648 2.00 1.47

-80.8" 5.532 -94.98 -94.963 -25.18 -47.86 13.26 30.63 -96.021

— 1.5043 1.49960 1.49856 1.50795 1.49980 1.49839 1.5496 1.49400

6139. 4898. 4106. 3606. 3734. 3536. 3511. 4050. 3209.

308.31 562.12 591.76 617.16 630.29 617.01 616.19 (646)* 631.1

0.00432 0.00332 0.00343 0.00352 0.00348 0.00354 0.00357 0.00333 0.00355

41 42 43 44 45 46 47 48 49

50 51 52 53 54 55

Methyl alcohol Ethyl alcohol Carbon monoxide Carbon dioxide Hydrogen sulfide Sulfur dioxide

CH4 O C 2 H6 O CO CO2 H2 S SO2

32.042 46.069 28.010 44.010 34.082 64.065

64.67 78.26 -191.45 -78.464* -60.266 -9.94

35.44 17.903 — — 2859.7 630.2

-97.65 -114.1 -204.99* -56.56* -85.48* -75.47*

1.33028 1.36345 1.00036* 1.00049* 1.00061* 1.00062*

8097. 6148. 3494. 7374. 8963. 7884.

512.60 513.88 132.86 304.11 373.37 430.8

0.00368 0.00362 0.00329 0.00214 0.00288 0.00190

50 51 52 53 54 55

56 57 58 59 60 61 62 63 64

Ammonia Air Hydrogen Oxygen Nitrogen Chlorine Water Helium Hydrogen chloride

NH3 N 2 + O2 H2 O2 N2 Cl 2 H2O He HCl

17.0305 28.9625 2.0159 31.9986 28.0134 70.9054 18.0153 4.0026 36.461

-33.32 -194.34 -252.850* -182.954* -195.798 -33.95 99.974* -268.95 -85.14

1555. — — — — 1146. 7.3849 — 6547.

-77.69* — -259.347* -218.792* -209.997* -100.95 0.000 — -114.17*

1.00036* 1.00028* 1.00013* 1.00027* 1.00028* 1.3878* 1.33347 1.00003* 1.00042

11350. 3771. 1293. 5043. 3398. 7977. 22064. 227.5 8310.

405.5 132.43 33.0 154.59 126.21 416.86 647.10 5.20 324.68

0.00425 0.00323 0.03185* 0.00229 0.00318 0.00175 0.003102 0.01436 0.00222

56 57 58 59 60 61 62 63 64

Vapor pressure, kPa(abs), 40˚C

Freezing point,˚C 101.3250 kPa(abs)

Boiling Point, åC 101.3250 kPa(abs)

Methane Ethane Propane lsobutane n-Butane

Compound

Formula

1 2 3 4 5

Number

Molar mass (Molecular weight)

Critical constants

(9700) 1691. 459.0 338.3 366.5 477.4 141.65 269. 436.1 123.8

5/99

23-2

Revised (5-99)

FIG. 23-2 (Cont’d) Physical Constants

23-3

FIG. 23-2 (Cont’d) Physical Constants

23-4

FIG. 23-2 (Cont’d) Notes and References for the Table of Physical Constants

23-5

FIG. 23-2 (Cont’d) Notes and References for the Table of Physical Constants

23-6

FIG. 23-2 (Cont’d) Notes and References for the Table of Physical Constants

23-7

FIG. 23-2 (Cont’d) Notes for the Table of Physical Constants a. b. c. d. e.

f. g. h. i. j. k. m. n. A.

B. C.

Values in parentheses are estimated values. The temperature is above the critical point. At saturation pressure (triple point). Sublimation point. The + sign and number following specify the number of cm3 of TEL added per gallon to achieve the ASTM octane number of 100, which corresponds to that of Isooctane (2,2,4Trimethylpentane). These compounds form a glass. Average value from octane numbers of more than one sample. Saturation pressure and 15°C. Index of refraction of the gas. Densities of the liquid at the normal boiling point. Heat of sublimation. Equation 2 of the reference was refitted to give: a = 0.7872957; b = 0.1294083; c = 0.03439519. Normal hydrogen (25% para, 75% ortho).

p.

An extrapolated value.

q.

Gas at 15°C and the liquid at the normal boiling point.

r.

Fixed points on the 1968 International Practical Temperature Scale (IPTS-68).

s.

Fixed points on the 1990 International Temperature Scale (ITS-90).

t.

Densities at the normal boiling point are: Ethane, 554.0 [29]; Propane, 581.0 [28]; Propene, 609.1 [5]; Hydrogen Chloride, 1192 [43]; Hydrogen Sulfide, 949.0 [25]; Ammonia, 681.6 [43]; Sulfur Dioxide, 1462 [43].

u.

Technically, water has a heating value in two cases: net ((2.466 MJ/kg) when water is liquid in the reactants, and gross (+1.879 MJ/m3) when water is gas in the reactants. The value is the ideal heat of vaporization (enthalpy of the ideal gas less the enthalpy of the saturated liquid at the vapor pressure). This is a matter of definition; water does not burn.

v.

Extreme values of those reported by reference 19.

Molar mass (molecular mass) is based upon the following atomic weights: C = 12.011; H = 1.00794; O = 15.9994; N = 14.0067; S = 32.066; Cl = 35.4527. The values were rounded off after calculating the molar mass using all significant figures in the atomic weights. Boiling point: the temperature at equilibrium between the liquid and vapor phases at 101.3250 kPa. Freezing point: the temperature at equilibrium between the crystalline phase and the air saturated liquid at 101.3250 kPa.

J.

The liquid value is not rigorously CP, but rather it is the heat capacity along the saturation line CS defined by: CS = CP – T (∂V/∂T)P(∂P/∂T)S. For liquids far from the critical point, CS ≈ CP.

K.

The heating value is the negative of the enthalpy of combustion at 15°C and 101.3250 kPa (abs.) in an ideal reaction (one where all gasses are ideal gasses). For an arbitrary organic compound, the combustion reaction is: CnHmOhSjNk (s,l,or,g) + (n + m/4 – h/2 + j) O2(g) → n CO2(g) + m/2 H2O (g or l) + k/2 N2(g) + j SO2(g), where s, l and g denote respectively solid, liquid and ideal gas. For gross heating values, the water formed is liquid; for net heating values, the water formed is ideal gas. Values reported are on a dry basis. To account for water in the heating value, see GPA 2172. The MJ/kg liquid column assumes a reaction with the fuel in the liquid state, while the MJ/m3 ideal gas column assumes the gas in the ideal gas state. Therefore, the values are not consistent if used in the same calculation, e.g. a gas plant balance.

L.

The heat of vaporization is the enthalpy of the saturated vapor at the boiling point at 101.3250 kPa minus the enthalpy of the saturated liquid at the same conditions.

D.

The refractive index reported refers to the liquid or gas and is measured for light of wavelength corresponding to the sodium D-line (589.26 nm).

E.

The relative density: ρ(liquid, 15°C)/ρ(water, 15°C). The density of water at 15°C is 999.10 kg/m3.

F.

The temperature coefficient of density is related to the expansion coefficient by: (∂ρ/∂T)P/ρ = –(∂ρV/∂T)P/V, in units of 1/T.

G.

Pitzer acentric factor: ω = –log10(P/Pc) –1, P at T = 0.7 Tc Compressibility factor of the real gas, Z = PV/RT, is calculated using the second virial coefficient. The density of an ideal gas relative to air is calculated by dividing the molar mass of the of the gas by 28.9625, the calculated average molar mass of air. See ref. 34 for the average composition of dry air. The specific volume of an ideal gas is calculated from the ideal gas equation. The volume ratio is: V(ideal gas)/V(liquid in vacuum).

H. I.

M. Air required for the combustion of ideal gas for compounds of formula CnHmOhSjNk is: V(air)/V(gas) = (n + m/4 - h/2 + j)/0.20946.

COMMENTS 1.987216 calth/(K• mol) 1.985887 Btu(I.T.)/(R(lb•mol) Conversion factors: 1 m3 = 35.31467 ft3 = 264.1721 gal.(U.S.) 1 kg = 2.204623 lbm 1 kg/m3 = 0.06242795 lbm/ft3 =0.001 g/cm3 1 kPa = 0.01 bar = 0.009869233 atm = 0.1450377 psia 1 atm = 101.3250 kPa = 14.69595 psia = 760 Torr 1 kJ = 0.2390057 kcalth = 0.2388459 kcal (I.T.) = 0.9478172 Btu (I.T.)

Units: reported values are in SI units based on the following: mass: kilogram, kg length: meter, m temperature: International Temperature of 1990 (ITS-90), where 0°C = 273.15 K. Other derived units are: volume: cubic meter, m3 pressure: Pascal, Pa (1 Pa = N/m2) energy: Joule, J Gas constant, R: 8.314510 J/(K• mol) 0.008314510 m3(kPa/(K•mol)

23-8

Revised (5-99)