Compression factor standard

Component Mole fraction Vj Gross Heating Value BTU/scf t-e) yiL=i Compressibility Factor Standard Conditions Zj yj yi -zj ... 

The confinement term is unique because it alone causes a dependence of the binding free energy on the choice of unit concentration in the standard state the volume available per ligand molecule in the free state, and hence the compression factor, depend on the unit concentration. 

Meters are accurate within close limits as legislation demands. However, gas is metered on a volume basis rather than a mass basis and is thus subject to variation with temperature and pressure. The Imperial Standard Conditions are 60°F, 30inHg, saturated (15.56°C, 1913.7405 mbar, saturated). Gas Tariff sales are not normally corrected, but sales on a contract basis are. Correction may be for pressure only on a fixed factor basis based on Boyle s Law or, for larger loads, over 190,000 therms per annum for both temperature and pressure using electronic (formerly mechanical) correctors. For high pressures, the compressibility factor Z may also be relevant. The current generation of correctors corrects for pressure on an absolute basis taking into account barometric pressure. 

The compressibility factor z of methane is always less than 1.0 in normal temperature ranges (i.e., between —40° and 50° C). Furthermore, the compressibility factor decreases as the pressure rises or the temperature falls. Therefore, less energy is needed to pump a given volume of methane (measured at standard volume) at any given normal temperature than would be expected at that temperature if the methane were an ideal gas. This effect is more marked at higher pressures. Similarly, as the pressure is increased at a constant temperature, more methane (measured at standard volume) can be stored in a given volume than would be predicted from the ideal gas equation. 

Equation 6-17 can be used to calculate gross heating value or net heating value. In either case, the values must be converted from ideal gas to real gas at standard conditions. This is done by dividing the ideal value by compressibility factor of the gas at standard conditions. 

Compressibility factor at standard conditions may be calculated using z-factors tabulated in Appendix A, where... 

First, calculate gross heating value of ideal gas and compressibility factor of the gas at standard conditions. 

From a data collection with 349 experimental values for the critical compression factor (Reid et al., 1987) obtained with organic and inorganic compounds and elements, a mean value of Zc = 0.2655 is obtained with a standard deviation of a = 0.0346. 

Clausius/Clapeyron equation, 182 Coefficient of performance, 275-279, 282-283 Combustion, standard heat of, 123 Compressibility, isothermal, 58-59, 171-172 Compressibility factor, 62-63, 176 generalized correlations for, 85-96 for mixtures, 471-472, 476-477 Compression, in flow processes, 234-241 Conservation of energy, 12-17, 212-217 (See also First law of thermodynamics) Consistency, of VLE data, 355-357 Continuity equation, 211 Control volume, 210-211, 548-550 Conversion factors, table of, 570 Corresponding states correlations, 87-92, 189-199, 334-343 theorem of, 86... 

Determination of the Z Factor. The data obtained in the determination of r and may also be used to evaluate the compressibility factor Z (and consequently v) as a function of pressure at reservoir tem-peratui-e. Since the volume of the gas phase is known both under reservoir conditions and standard conditions the value of Z may be computed using the equation... 

Explain in your own words and without the use of jargon (a) the three ways of obtaining values of physical properties (b) why some fluids are referred to as incompressible (c) the liquid volume additivity assumption and the species for which it is most likely to be valid (d) the term equation of state (e) what it means to assume ideal gas behavior (f) what it means to say that the specific volume of an ideal gas at standard temperature and pressure is 22.4 L/mol (g) the meaning of partial pressure (h) why volume fraction and mole fraction for ideal gases are identical (i) what the compressibility factor, z, represents, and what its value indicates about the validity of the ideal gas equation of state (j) why certain equations of state are referred to as cubic and (k) the physical meaning of critical temperature and pressure (explain them in terms of what happens when a vapor either below or above its critical temperature is compressed). 

Given any three of the quantities P, V (or F), n (or n), and T for an ideal gas, (a) calculate the fourth one either directly from the ideal gas equation of state or by conversion from standard conditions (b) calculate the density of the gas and (c) test the assumption of ideality either by using a rule of thumb about the specific volume or by estimating a compressibility factor and seeing how much it differs from 1. 

From a compressibility factor chart, Z = 0.86. The rate of heat input due to fire and flow rate of the vapor release can be determined by Equations 5-53 and 5-45. Table 5-12 gives the input data and results of vinyl chloride monomer. The results show that the calculated relief valve orifice area is 2.172 in. The nearest standard orifice size is L, with an orifice area of 2.853 in. ... 

After the compressibility factor has been arrived at, the N2 space factor can be determined. The N2 space factor is the volume of N2 gas at a particular temperature and pressure that will occupy one standard cubic... 

Apart from the direct conformational changes in enzymes, which may occur at very high pressures, pressure affects enzymatic reaction rates in SCFs in two ways. First, the reaction rate constant changes with pressure according to transition stage theory and standard thermodynamics. Theoretically, one can predict the effect of pressure on reaction rate if the reaction mechanism, the activation volumes and the compressibility factors are known. Second, the reaction rates may change with the density of SCFs because physical parameters, such... 

Let us assume for purposes of this paper that we can know the composition of a gas from some suitable measurement. It is then possible, in principle, to calculate pertinent properties such as heating value, relative density, compressibility factor. Unfortunately, as often happens in practice, these supposedly unambiguous calculations become clouded by accepted procedirres, misconceptions, misguided regulations. The discussion in this paper attempts to dispel the misconceptions and to clarify the accepted procedures. As for the regulations, it is only possible to wish that they would not always choose the path of maximum irrationality and to try to perform the calculations in the least offensive (technically) marmer possible. The calculations described in this paper reflect those suggested in GPA Standard 2172-85. However, this paper contains considerable amplification and discussion of the techniques. 

Gas Producers Association, Calculation of Gross Heating Value, Relative Density and Compressibility Factor for Natural Gas Mixtures from Compositional Analysis, GPA Standard 2172-86 (1986). 

W. M. Haynes and R. D. Goodwin, Thermophysical Properties of Normal Butane from 135 to 700 K at Pressures to 70 MPa, U.S. Dept, of Commerce, National Bureau of Standards Monograph 169, 1982, 192 pp. Tabulated data include densities, compressibility factors, internal energies, enthalpies, entropies, heat capacities, fugacities and more. Equations are given for calculating vapor pressures, liquid and vapor densities, ideal gas properties, second virial coefficients, heats of vaporization, liquid specific heats, enthalpies and entropies. 

Thus, a system of nonlinear equations is available to evaluate the true monomer concentrations Zn, which can be solved with standard methods [17). The compressibility factor is equal to the ratio between the number of associates and the number of monomers in the associates ... 

The parameter Cj for the point j is unity when the deviation between the value, in this case pressure, calculated from the equation of state py calc, T (meas), p (meas), n and the experimental value p jmeas, T (meas), p (meas) is equal to the experimental uncertainty Opj. Typically, for a reference equation of state, the should be less than unity for almost all data (typically > 95 % of the points if a is considered to be equal to two times the standard deviation as appropriate for an expanded uncertainty at a confidence interval of 0.95). In eq 12.1 the calculated pressure depends on the parameter vector n, thus on the coefficients of the equation of state that are fitted. In practice, the dimensionless compression factor Z is commonly used instead of the pressure. Thus, the residual becomes... 

In order to calculate the phase coexistence predicted by TPTl, expressions for the compressibility factor and chemical potential are also required. The compressibility factor is obtained by using the following standard thermodynamic relation ... 

Source van der Waals constants are from the CRC Handbook of Chemistry and Physics, 95th ed., David R. Lide (ed.)., Boca Raton, FL Taylor Francis Group, 2015. Compressibility factors are calculated by using data from the National Institute of Standards and Technology (NIST) Chemistry WebBook, available online at http //webbook.nist.gov/chemistry/. 

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