Selecting Physical Property Method

Sd Components Properties O Specifications EE) Prcperty Methods ffi ij Estimation BBC] Molecular Struct . RE .ftl Parameters D Data Cj Analysis 513(1 Prop-Sets BEiD Adrtnced O CAPE-OPBMPad. - Flowsheet h. Streams h Blocks Cl Utilities Reactions 

Note that selecting a proper physical property method is extremely important for obtaining reliable simulation results of a process flowsheet. Aspen Physical Property System gives the recommended classes of property methods for different applications. The phase equilibrium behavior predicted by the selected physical property method should be compared to experimental data for validation purpose. The experimental data that can typically be found in literamre includes the Txy and yx data binary and ternary LLE data VLLE data and azeotropic information. For details of how to validate the prediction of the selected physical property method, please refer to Chapter 2. 

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Figure 2.40 (a) Selection physical property method (b) Chao-Seader method chosen. 

The next steps arc entering components and selecting physical property methods as in previous Sections 3.1.2 and 3.1.3. Notice that only NRTL, UNIQUAC, or UNIFAC should be selected because we need to describe LLE in this decanter operation. 

TABLE 18.7 Selected Physical Properties, Sources, and Methods of Preparation for the Croup 2A Elements... 

One of the most important issues involved in distillation calculations is the selection of an appropriate physical property method that will accurately describe the phase equilibrium of the chemical component system. The Aspen Plus library has a large number of alternative methods. Some of the most commonly used methods are Chao-Seader, van Laar, Wilson, Unifac, and NRTL. 

In most design situations, there is some type of data that can be used to select the most appropriate physical property method. Often VLB data can be found in the literature. The multivolume DECHBMA data books provide an extensive source of data. 

The ternary system containing isopropanol, water, and cyclohexane is used as an example to show how to obtain the prediction of azeotropes in Aspen Plus. After inputting components and the physical property method, the following route is selected Tools Conceptual... 

The basic thermoanalytical methods reveal changes in the state of the sample by direct determination of the sample single property. In addition to such most widespread measurements of the pre-selected physical property of the sample [3], indirect measurements can also be carried out to follow the properties of the sample adjacent environment as an implied response to changes in the sample properties. If the sample property serves, at the same time, as a measured quantity to indicate the requested property of the test material, we deal with single arrangement, such as temperature in the case of heating and cooling curves. Differential methods are those in which the measured quantity is the... 

Proper choices of inhibitors should be made by matching the appropriate inhibitor chemistry with the corrosion conditions and by selection of appropriate physical properties for the application conditions. Method of application and system characteristics must be considered when selecting physical properties of an inhibitor. 

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