Modification of Hall-Yarborough Equation of State For Predicting Gas Compressibility Factors

2019 ◽  
Author(s):  
Ibrahim Ayuba ◽  
S. O. Isehunwa ◽  
M. B. Adamu ◽  
A. Usman ◽  
M. N. Bello
Keyword(s):  
Equation Of State ◽  
Compressibility Factors ◽  
Gas Compressibility

Equation of state of a Lennard-Jones 12-6 pairwise additive fluid

1980 ◽  
Vol 45 (4) ◽  
pp. 977-983 ◽  
Author(s):  
Jan Sýs ◽  
Anatol Malijevský
Keyword(s):  
Equation Of State ◽  
Empirical Equation ◽  
The State ◽  
Critical Properties ◽  
Lennard Jones ◽  
State Behaviour ◽  
Compressibility Factors

An empirical equation of state was proposed, which is based on pseudoexperimental data on the state behaviour. The equation can be used at reduced temperatures from the range 0.7-100.0 and reduced densities up to 2. Calculated compressibility factors and critical properties agree well with available literature data.

A Comprehensive Review of Recent Advances in the Estimation of Natural Gas Compressibility Factor

2021 ◽  
Author(s):  
Oluwasegun Cornelious Omobolanle ◽  
Oluwatoyin Olakunle Akinsete
Keyword(s):  
Artificial Intelligence ◽  
Equation Of State ◽  
Compressibility Factor ◽  
Operating Conditions ◽  
Measurement Equation ◽  
Comprehensive Review ◽  
Holistic Understanding ◽  
Deviation Factor ◽  
Gas Compressibility ◽  
Limited Accuracy

Abstract Accurate prediction of gas compressibility factor is essential for the evaluation of gas reserves, custody transfer and design of surface equipment. Gas compressibility factor (Z) also known as gas deviation factor can be evaluated by experimental measurement, equation of state and empirical correlation. However, these methods have been known to be expensive, complex and of limited accuracy owing to the varying operating conditions and the presence of non-hydrocarbon components in the gas stream. Recently, newer correlations with extensive application over wider range of operating conditions and crude mixtures have been developed. Also, artificial intelligence is now being deployed in the evaluation of gas compressibility factor. There is therefore a need for a holistic understanding of gas compressibility factor vis-a-vis the cause-effect relations of deviation. This paper presents a critical review of current understanding and recent efforts in the estimation of gas deviation factor.

Performance Testing of Centrifugal Compressors: Schultz Compressibility Factors

2015 ◽  
Author(s):  
Matt Taher
Keyword(s):  
Equation Of State ◽  
Natural Gas ◽  
Performance Testing ◽  
Centrifugal Compressors ◽  
Real Gas ◽  
Gas Compression ◽  
Compressibility Factors

ASME PTC-10 [2009] recognizes inaccuracies involved in using the generalized charts to calculate Schultz compressibility factors for real gas compression. However, it neither addresses a method to develop the compressibility factors, nor does it specify when to use calculated compressibility factors rather than using generalized values. Using inaccurate generalized values for Schultz compressibility factors may lead to erroneous calculation of polytropic exponents and polytropic work. This paper employs the LKP equation of state to directly calculate Schultz compressibility factors for a mixture of hydrocarbons typically found in natural gas. The results are compared with the values of compressibility factors from the generalized compressibility charts.

scholarly journals Volumetric Measurements of Methane-Coal Adsorption and Desorption Isotherms—Effects of Equations of State and Implication for Initial Gas Reserves

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 2022 ◽  
Author(s):  
Jamiu M. Ekundayo ◽  
Reza Rezaee
Keyword(s):  
Bituminous Coal ◽  
Equations Of State ◽  
Hysteresis Loops ◽  
Desorption Isotherm ◽  
Model Parameters ◽  
Adsorbed Gas ◽  
Desorption Isotherms ◽  
Compressibility Factors ◽  
Gas Compressibility ◽  
Adsorption Curve

This study presents the effects of equations of state (EOSs) on methane adsorption capacity, sorption hysteresis and initial gas reserves of a medium volatile bituminous coal. The sorption experiments were performed, at temperatures of 25 °C and 40 °C and up to 7MPa pressure, using a high-pressure volumetric analyzer (HPVA-II). The measured isotherms were parameterized with the modified (three-parameter) Langmuir model. Gas compressibility factors were calculated using six popular equations of state and the results were compared with those obtained using gas compressibility factors from NIST-Refprop® (which implies McCarty and Arp’s EOS for Z-factor of helium and Setzmann and Wagner’s EOS for that of methane). Significant variations were observed in the resulting isotherms and associated model parameters with EOS. Negligible hysteresis was observed with NIST-refprop at both experimental temperatures, with the desorption isotherm being slightly lower than the adsorption isotherm at 25 °C. Compared to NIST-refprop, it was observed that equations of state that gave lower values of Z-factor for methane resulted in “positive hysteresis”, (one in which the desorption isotherm is above the corresponding adsorption curve) and the more negatively deviated the Z-factors are, the bigger the observed hysteresis loop. Conversely, equations of state that gave positively deviated Z-factors of methane relatively produced “negative hysteresis” loops where the desorption isotherms are lower than the corresponding adsorption isotherms. Adsorbed gas accounted for over 90% of the calculated original gas in place (OGIP) and the larger the Langmuir volume, the larger the proportion of OGIP that was adsorbed.

scholarly journals Statistical mechanics of hard spheres: the scaled particle theory of the hard sphere fluid revisited

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Bruno Baeyens
Keyword(s):  
Equation Of State ◽  
Hard Sphere ◽  
Hard Spheres ◽  
Virial Coefficients ◽  
Scaled Particle Theory ◽  
Particle Theory ◽  
Simulation Data ◽  
Hard Sphere Fluid ◽  
Two Parameters ◽  
Compressibility Factors

The aim of this paper is to exhaust the possibilities offered by the scaled particle theory as far as possible and to confirm the reliability of the virial coefficients found in the literature, especially the estimated ones: B i for i > 11. In a previous article (J.Math.Phys.36,201,1995) a theoretical equation of state for the hard sphere fluid was derived making use of the ideas of the so called scaled particle theory which has been developed by Reiss et al.(J.Chem.Phys.31,369,1959). It contains two parameters which could be calculated. The equation of state agrees with the simulation data up to high densities, where the fluid is metastable. The derivation was besed on a generalized series expansion. The virial coefficients B 2 , B 3 and B 4 are exactly reproduced and B 5 , B 6 and B 7 to within small deviations, but the higher ones up to B 18 are systematically and significantly smaller than the values found in the literature. The scaled particle theory yields a number of equations of which only four were used. In this paper we make use of seven equations to calculate the compressibility factors of the fluid. They agree with the simulation data slightly better than those yielded by the old equation. Moreover, the differences between the calculated virial coefficients B i and those found in the literature up to B 18 are very small (less than 4 percent).

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