API TR 2575-2014 pdf free download

API TR 2575-2014 pdf free download.Measurement of Thermally Cracked Gas.
3.3 Units and Conversions The units used in the basic formulation of the equations and in the associated computer subroutines are SI units. The subroutines use the following units for the absolute temperature in kelvins (K), pressure in megapascals (MPa), and molar density in moles per cubic decimeter (mol/dm 3 ). The value of the gas constant is 0.008314472 KJ/mol-K. Conversion factors are required for conversions to and from other units. Consistent conversion factors for use with the TCG method are given in Table 1. When possible, the conversion factors given in Table 1 correspond to international standards (GPA 2172-2009 and ISO 6976). Any differences in values used in this program and later values are within the experimental uncertainty in the validation data. Hence any unit conversion changes are unlikely to affect the uncertainty of the calculations. It is recommended that any subsequent changes be ignored unless the agency promoting the change provides a detailed cost impact of the change on industry. 4 Types of Gases Covered This research document applies to TCG mixtures that may occur in refinery operations. Table 2 provides a simplified list of illustrative TCG mixture example components. A number of components have been excluded either because they were not present in the data or because of low concentration amounts. This shall not be construed to mean those components are not important for TCG calculations. It simply means those components were not available to the research stage data sets. It is recommended that users obtain additional data to validate performance for their fluid mixtures for their operating conditions.
Application and operation conditions should be verified by obtaining experimental data for other conditions. The calculation method should not be used outside of the specified boundaries without supporting experimental data, nor should it be used in the vicinity of the critical point. It cannot be used for two-phase calculations. It is recommended that methods be considered with broader applicability (e.g. API MPMS Ch. 14.2 or GERG 2008 methods) be applied to extended operating conditions until API completes its TCG mixture data work. NOTE API MPMS Ch. 14.2 and GERG 2008 methods were not explicitly developed for TCG mixtures. These methods have unknown uncertainties for TCG mixtures at the time this technical report was produced. In Section 1.3.2 of API MPMS Ch. 14.2/AGA Report No. 8/GPA 8185, no reference is made to the application of the equations to TCG mixtures. This section indicates that the performance for calculations for gas mixtures that do not fall in the normal range of gas mixtures should be verified by other means (i.e. measured data representing commercial TCG mixtures). Figure 1 provides an overview of the custody transfer measurement and operating pressure and temperature region for TCGs. 6 TCG Calculation Method Overview 6.1 Overview of Requirements The user of this report has to be aware of the custody transfer operating conditions and the applicability of the method over those conditions.
The user is required to provide the operating temperature, pressure, and a detailed gas analysis as input for the method (i.e. the mole fractions or mole percentages of the components in the TCG mixture). At present, an insufficient database is available for validating component substitutions for many olefinic compounds. Preliminary analysis for large mole fraction components suggests that uncertainties increase when component substitution is utilized. The effect of low mole fraction concentrations of heavy olefinic compounds and sour compounds has not been experimentally determined. 6.2 TCG Reference Mixture Data The recommended methodology for evaluating mixture data uncertainty can be found in API MPMS Ch. 14.2/AGA Report No. 8/GPA 8185. 6.3 TCG Method Uncertainty In general, the target uncertainty in the gas phase for any TCG method is the same as other industry measurement documents such as found in API MPMS Ch. 14.2. The target uncertainty for TCG custody transfer is illustrated in Figure 1 for gases having the normal range of gas characteristics identified in Table 3.