There are six Reid Vapor Pressure (RVP) calculation methods in PRO/II:
APINAPHTHA - The RVP is obtained from a nomograph in the API Databook (Figure 5B1.1, pg. 5-29) which relates the RVP to the slope of the ASTM D86 distillation curve at the 10% volume point and the temperature. This method is useful for gasoline mixtures.
APICRUDE - For this method the TVP is determined first, and then the RVP is obtained from a nomograph in the API databook (Fig. 5B1.2, pg.5-31) which relates the RVP to the temperature and the TVP. This method is useful for crude oils.
P323 - This is the method used in PROCESS. It is obsolete now, but is still included in PRO/II for comparing results with PROCESS. Dry air is added to the liquid mixture, sealed, and allowed to equilibrate at a temperature of 100 F. The measured pressure of the sample is then subtracted from the atmospheric pressure to obtain the RVP in psi. PRO/II rigorously simulates all steps in this method.
D323 (wet method) - This 1982 ASTM method is again rigorously simulated by PRO/II. This method mixes the liquid hydrocarbon stream with dry air and liquid water. The resultant mixture is sealed, allowed to reach equilibrium, and the pressure in the chamber measured at 100 F. The RVP in units of psi is obtained by subtracting the atmospheric pressure from the measured pressure. (See article #1875 in the NATS article database.)
D4953 (dry method) - This 1991 ASTM method is similar to the D323 method, except that no liquid water is added to the mixture. However, the air sample added is assumed to be saturated with water vapor. This method is useful for gasolines containing oxygenates such as alcohols, which separate out with water.
D5191 - This is based on the 1991 ASTM-D5191 method. Sample is evacuated. Applicable for volatile liquid petroleum products.
About PRO/II: PRO/II is the major product in the Process Engineering Suite (PES). This process simulation software optimizes plant performance by improving process design, operational analysis, and performing engineering studies. It is designed to perform rigorous heat and material balance calculations for a wide range of chemical processes. PRO/II allows users to evaluate the use of heat integration with case studies, rigorously evaluate process improvements with the help of a process flow diagram (PFD), or model crude distillation units. PRO/II offers a wide variety of thermodynamic models to virtually every industry and is incredibly cost effective, decreasing both capital and operating costs.
Technical Support: As always, feel free to reach out to your local technical support team for more information.
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