Henry components

Table 10.8 presents a comparison of SR-Polar EOS and Wilson-HOC with Henry components. The predictions by the two methods are in good agreement, although surprisingly for the ability of SR-Polar to account for liquid-phase nonideality. 

Species Molar fraction SR-Polar Wilson-HOC + Henry components ... 

Next, we present results obtained by using Aspen Plus [23], Using the Uniquac-RK model with Henry components for supercritical gases ensures correct description of the absorption-desorption process. Table 11.7 shows the composition of streams around the reactor and the first separation step. 

Example 4.32 Column grand composite curves in methanol plant Table 4.16 describes the existing base case operations for columns 1 and 2 of the methanol plant obtained from the converged simulations using the RKS equation of state to estimate the vapor properties. The activity coefficient model, NRTL, and Henry components method are used for predicting the equilibrium and liquid properties. 

Absorption in various solvents of gases containing both sub-critical and supercritical components. For Instance, by the absorption in water of a gas containing COj, Hj, CH4 and CH3OH, the first three species may be treated as Henry components, while for CH3OH is subcritical. By asymmetric convention applied to all components the thermodynamic treatment is consistent and accurate. 

The procedure follows the same route, with the difference that NHj is defined as a Henry component. The Henry-constant can be obtained from the slope at zero concentration. The back computation of data gives very closed results with the symmetric convention therefore they are not given again. Note that the Henry coefficients can be simultaneously regressed. A temperature dependency may be... 

Ah - and ideal gas state, calculated with an EOS specific enthalpy of solution of Henry component i ( mol ... 

Exiass- total column exergy loss from the converged simulation by Aspen Plus with Soave—Redlich—K, NRTL and Henry components methods. 

Cleaial local KmodelsyBIPs r Cleaialti BIPs rISet local KmodefeyBlN r Seth BIPs f Set Henry components... 

For the ethanol production process (including the CHP), the non-random two liquid (NRTL) property method with Henry components was used, which was also recommended by the Aspen Plus guidelines, as it is suitable for, among others, liquid-phase reactions and azeotropic alcohol separation. Some compounds involved in the ethanol production do not exist in the conventional Aspen Plus database. Therefore, physical properties of these components were taken from a database developed by the National Renewable Energy Laboratory (NREL) for biofuel components (Wooley et al., 1999 Aspentech, 2011). 

Henry s constant is the standard-state fugacity for any component i whose activity coefficient is normalised by Equation (14). ... 

In a binary liquid solution containing one noncondensable and one condensable component, it is customary to refer to the first as the solute and to the second as the solvent. Equation (13) is used for the normalization of the solvent s activity coefficient but Equation (14) is used for the solute. Since the normalizations for the two components are not the same, they are said to follow the unsymmetric convention. The standard-state fugacity of the solvent is the fugacity of the pure liquid. The standard-state fugacity of the solute is Henry s constant. 

The use of Henry s constant for a standard-state fugacity means that the standard-state fugacity for a noncondensable component depends not only on the temperature but also on the nature of the solvent. It is this feature of the unsymmetric convention which is its greatest disadvantage. As a result of this disadvantage special care must be exercised in the use of the unsymmetric convention for multicomponent solutions, as discussed in Chapter 4. 

Table 3 shows results obtained from a five-component, isothermal flash calculation. In this system there are two condensable components (acetone and benzene) and three noncondensable components (hydrogen, carbon monoxide, and methane). Henry s constants for each of the noncondensables were obtained from Equations (18-22) the simplifying assumption for dilute solutions [Equation (17)] was also used for each of the noncondensables. Activity coefficients for both condensable components were calculated with the UNIQUAC equation. For that calculation, all liquid-phase composition variables are on a solute-free basis the only required binary parameters are those for the acetone-benzene system. While no experimental data are available for comparison, the calculated results are probably reliable because all simplifying assumptions are reasonable the... 

Table 4.19 gives the Henry constants for a few common gaseous components. The chemical nature is also a dominant factor. The effect of temperature is moderate note that the solubility passes through a minimum that depends on the hydrocarbon in question and that it is around 100°C. 

Equation 6 shows that the adsorption of component 1 at a partial pressureis reduced in the presence of component 2 as a result of competition for the available surface sites. There ate only a few systems for which this expression (with 5 1 = q 2 = 5 ) provides an accurate quantitative representation, but it provides useful quaUtative or semiquantitative guidance for many systems. In particular, it has the correct asymptotic behavior and provides expHcit recognition of the effect of competitive adsorption. For example, if component 2 is either strongly adsorbed or present at much higher concentration than component 1, the isotherm for component 1 is reduced to a simple linear form in which the apparent Henry s law constant depends onp. ... 

Many simple systems that could be expected to form ideal Hquid mixtures are reasonably predicted by extending pure-species adsorption equiUbrium data to a multicomponent equation. The potential theory has been extended to binary mixtures of several hydrocarbons on activated carbon by assuming an ideal mixture (99) and to hydrocarbons on activated carbon and carbon molecular sieves, and to O2 and N2 on 5A and lOX zeoHtes (100). Mixture isotherms predicted by lAST agree with experimental data for methane + ethane and for ethylene + CO2 on activated carbon, and for CO + O2 and for propane + propylene on siUca gel (36). A statistical thermodynamic model has been successfully appHed to equiUbrium isotherms of several nonpolar species on 5A zeoHte, to predict multicomponent sorption equiUbria from the Henry constants for the pure components (26). A set of equations that incorporate surface heterogeneity into the lAST model provides a means for predicting multicomponent equiUbria, but the agreement is only good up to 50% surface saturation (9). 

For the separate determination of the four principal components in the total alkaloids, the method in general use is based on the isolation of quinine and cinchonidine as d-tartrates, of cinchonine as the base in virtue of its sparing solubility in ether, and of quinidine as the hydriodide. Types of this method have been described by Chick, and special modifications designed for use in the analysis of totaquina are given in the British Pharmacopoeia 1932 and in a special report by the Malaria Commission of the League of Nations. Goodson and Henry have critically examined this process and shown that, with care, it gives satisfactory... 

The most important equilibrium pliase relationship is diat between liquid and vapor. Raoult s mid Henry s laws theoretically describe liquid-vapor behavior mid, mider certain conditions, are applicable in practice. Raoult s law, sometimes useful for mi.vtures of components of similar structure, states diat die partial pressure of any component in die vapor is equal to die product of the vapor pressure of the pure component and die mole fracdon of tliat component in die liquid. It may be written in die following maimer... 

To accommodate the step-by-step, recycling and checking for convergences requires input of vapor pressure relationships (such as Wilson s, Renon s, etc.) through the previously determined constants, latent heat of vaporization data (equations) for each component (or enthalpy of liquid and vapor), specific heat data per component, and possibly special solubility or Henry s Law deviations when the system indicates. 

Kj = 14.7 (Hj)/176, where Hj is Henry s constant expressed as atm/mol fraction for each component. Note that conventional K charts are only applicable to hydrocarbon oil systems, and do not apply for any special solvents. 

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