I. Pressure-Volume-Temperature Relations of Paraffin Hydrocarbons

Brown, George Granger; Souders, Mott; Smith, Richard L.

doi:10.1021/ie50269a010

Cited by 17 publications

(9 citation statements)

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“…In order to establish a basis for estimating the specific heats of vapors differing widely in nature from Midcontinent fractions, a correction factor was derived from the data on pure hydrocarbons as a function of the characterization factor in the same manner as described above for the liquid state. The function is mathematically expressed as follows: f(K) =0.12K -0.41 (5) This function is also adjusted to equal unity for Midcontinent fractions having a characterization factor of 11.8. The equation proposed by Bahlke and Kay (1) is accordingly modified to apply to other stocks merely by multiplying by the function derived from Equation 5: cP = ^~^-S (t + 670) (0.12K -0.41) (6) where cp = sp.…”

Section: Specific Heat (Vapor State)mentioning

confidence: 99%

“…These calculations are made by rigorous thermodynamic relationships and are reliable where accurate P-V-T data are available. Cope, Lewis, and Weber (6) and Brown, Souders, and Smith (5) have presented a modification of the reduced equation of state in which compressibility factors are expressed as a function of only the reduced temperature and pressure. This function is shown to be approximately constant for different hydrocarbon vapors.…”

Section: Rankinementioning

confidence: 99%

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Improved Methods for Approximating Critical and Thermal Properties of Petroleum Fractions

Watson¹,

Nelson²

1933

Ind. Eng. Chem.

122

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H E published literature and the files of every petroleum laboratory contain many data on the physical p r o p T erties of petroleum fractions, the value of which is limited by the difficulty of correlating them into relationships of general applicability. Such correlations should permit prediction of difficultly measurable properties from the results of standardized inspections such as the Engler distillation and the specific gravity. I n our present state of knowledge it is necessary to resort to many purely empirical relationships which have no apparent theoretical foundation but are valuable in that they correlate existing data with accuracy and permit its extrapolation with some degree of assurance. The relationships presented below are for the most part of the empirical type based on consideration of the best data available at this time. It is recognized that in some cases they are not entirely Iogical and that in all cases the actual numerical values will be subject to revision as more data are collected. AVERAGE BOILING POINT Several different m e t h o d s of e s t a b l i s h i n g a so-called average boiling point of petroleum f r a c t i o n s have been in m o r e o r l e s s g e n e r a l use.By calculating an integrated a v e r a g e o r d i n a t e of the true boiling point curve, an accurate a v e r a g e boiling point may be o b t a i n e d . This average will be weighted on either a volum e t r i c o r a weight basis, depending on the units in which the distillation curve is plotted. An integrated average of the 100-cc. E n g l e r d i s t i l l a t i o n c u r v e s i m i l a r l y gives a fair approximation to the volumetric a v e r a g e boiling point with a tendency toward higher values than are obtained by averag-, ing a volumetric true boiling point curve.As a basis for the correlation of p h y s i c a l p r o p e r t i e s , part i c u l a r l y the so-called molal p r o p e r t i e s , a volumetrically weighted average boiling point offers a l e s s logical basis than what may be termed the "molal average boiling point." The molal average boiling point is less than the volumetric average because of the fact that the ratio of specific gravity to molecular weight is higher for the low-boiling members of a hydrocarbon series. Thus, in determining the average boiling point from a volumetric distillation curve, the lower boiling fractions should be given increased weighting in proportion to the variation with boiling point of this ratio of specific gravity to molecular weight. I n Figure 1 is presented a curve giving a correction to be subtracted from the volumetric average boiling point of a petroleum fraction in order to obtain an approximation to its molal average boiling point. This correction is expressed as a function of the slope of the 100-cc. Engler distillation curve and becomes zero as the slope of the curve approaches zero, denoting a pure compound. The general form of this curve was derived by plotting the ratio of specific gravity Two new concepts are introduced f o r correlatio...

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Section: Specific Heat (Vapor State)mentioning

confidence: 99%

Section: Rankinementioning

confidence: 99%

Improved Methods for Approximating Critical and Thermal Properties of Petroleum Fractions

Watson¹,

Nelson²

1933

Ind. Eng. Chem.

122

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“…In / = In P -dP (19) PV where Z = ^ , the compressibility factor Critical temperatures and critical pressures of a compound are necessary in order to use the compressibility factor for determining pressure-volume-temperature data or fugacity. The data on compounds from methane through octane have been tabulated (14). Numerous relationships for estimating critical temperatures from other physical properties have been suggested, but many of the required properties are not readily available (24,81,33,38,74,89).…”

Section: Fugacities and Ideal Solutionsmentioning

confidence: 99%

“…Usually the vapor pressure line, EC, should be curved slightly before reaching the critical point, C, so that the critical pressure line, Pc, is tangent to the vapor pressure line at the critical point, C. The fugacity of a liquid under its own vapor pressure is equal to the fugacity of the vapor. Under any other pressure the fugacity of the liquid is not the same as that of the saturated vapor but may be readily calculated (14) from the density of the liquid (87). The ideal solution is defined (44) as a solution in which fugacity of each component is proportional to the mole fraction of that component.…”

Section: Fugacities and Ideal Solutionsmentioning

confidence: 99%

Vapor Pressure and Vaporization of Petroleum Fractions

Katz¹,

Brown²

1933

Ind. Eng. Chem.

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“…Among the existing gas deviation factor estimation methods, most have shown acceptable accuracy for a huge range of temperature and pressure conditions that are commonly present in gas reservoirs. Initial gas deviation factor correlations were developed by Brown et al 17 and Cope et al, 18 which were further modified for the better accuracy with extended datasets, including binary components by Brown, 19 Brown and Holocomb, 15 and Standing and Katz. 7 The pseudoreduced pressure p pr and pseudoreduced temperature T pr can be defined by using eqs 5 and 6…”

Section: Introductionmentioning

confidence: 99%

New Correlation for the Gas Deviation Factor for High-Temperature and High-Pressure Gas Reservoirs Using Neural Networks

Tariq

Mahmoud

2019

Energy Fuels

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The gas deviation factor (Z-factor) is an effective thermodynamic property required to address the deviation of real gas behavior from that of an ideal gas. Empirical models and correlations to compute Z-factor based on equation of states are often implicit because they needed a huge number of iterations and thus were computationally very expensive. Many explicit empirical correlations are also reported in the literature to improve the simplicity; yet, no individual explicit correlation was formulated for the complete full range of pseudoreduced temperatures and pseudoreduced pressures, which demonstrates a significant research gap. The inaccuracy in determining the gas deviation factor will result in a huge error in computing subsequent natural gas engineering properties such as gas expansion factor (E g), formation volume factor (B g), gas compressibility (c g), and original gas in place. Previously reported empirical correlations provide better estimation of the gas deviation factor at lower pressures, but at higher reservoir pressures, their accuracies become questionable. One of the examples of high-pressure reservoirs is the abnormal pressured reservoir, where the reservoir pressure exists up to 20 000 psia. In this study, an improved Z-factor empirical correlation is presented in a linear fashion using a robust artificial intelligence tool, the artificial neural network (ANN). The new correlation is trained on more than 3000 data points from laboratory experiments obtained from several published sources. The proposed correlation is only a function of pseudoreduced temperature (T pr) and pseudoreduced pressure (p pr) of the gases, which makes it easier to implement than the reported implicit and complicated explicit correlations. The proposed correlation can be valid for p pr ranges between 0.1 and 40 and T pr ranges between 1.05 and 3.05. The accuracy and generalization capabilities of the proposed ANN-based correlation are also tested against previously published correlations at low and high gas reservoir pressures on an unseen published dataset. The comparative results on a published dataset show that the new correlation outperformed other methods of predicting Z-factor by giving less average absolute percentage error, less root-mean-square error, and high coefficient of determination (R 2). The error obtained was less than 3% compared to the measured data, while the other correlations predicted the gas deviation factor with an error up to 4% at low pressure and up to 20% at high pressure. The new proposed ANN-based correlation can be utilized to estimate the Z-factor at any pressure range (on which the model is trained) especially for high pressures. The new proposed correlation is very easy to be used, and it requires only the gas-specific gravity that is needed to determine the pseudocritical properties of the real gas and from which the Z-factor can be determined.

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I. Pressure-Volume-Temperature Relations of Paraffin Hydrocarbons

Cited by 17 publications

References 0 publications

Improved Methods for Approximating Critical and Thermal Properties of Petroleum Fractions

Improved Methods for Approximating Critical and Thermal Properties of Petroleum Fractions

Vapor Pressure and Vaporization of Petroleum Fractions

New Correlation for the Gas Deviation Factor for High-Temperature and High-Pressure Gas Reservoirs Using Neural Networks

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