Difference point equation reflux

The formulation of the operating line equations and equilibrium relationships and their graphical implementation is not restricted to the basic extractor configuration but can be applied to columns with multiple feeds and reflux streams. The resulting complexity is handled by breaking up the column into sections, each with its own difference point. This is demonstrated for a column with an intermediate feed, resulting in two sections. 

Equations (7.3-1 l)-(7.3-i3) demonstrate that the differences between adjacent streams in the culumn section above the feed plane are constant in amount and composition. These differences therefore may be represented by the single point A, on (he triangular diagram. The "difference point" d, is loealed in Fig. 7.3-8 from the following development in terais of the reflux ratio, GJGp,... 

DODS-ProPlot. This is a comprehensive profile plotting package which allows the user to plot single profiles, entire CPMs and ROMs, and their associated pinch points. There are 13 systems to choose from, each of which may be modeled either with a modified Raoult s law and the NRTL activity coefficient model, or with the ideal Raoult s law (does not model azeotropes), or with a constant relative volatility approximation where the software automatically determines the relative volatilities between components (this model also cannot account for azeotropic behavior). One also has the option to insert one s own constant volatilities. It is possible to plot the full DPE, the shortened DPE at infinite reflux (shown in Chapter 7) or the classic residue curve equation. Depending on the equation chosen, the user is free to specify any relevant parameters such as an R value, difference points, system... 

Achieving dynamic simulations that rigorously capmre the neat heat integration require the use of Flowsheet Equations in Aspen Dynamics. Two conditions must exist at each point in time during the dynamic simulation. First, the heat transfer in the condenser/reboiler must be equal to the product of the area, the overall heat-transfer coefficient, and the current temperature difference between the reflux drum of the high-pressure column and the base of the low-pressure column. These two temperatures both change dynamically as compositions and pressures vary. The pressure in the high-pressure column is not controlled but floats. 

The classical Hunsdiecker reaction (equation 18), involving the reaction of silver caiboxylates widi halogens, and the various associated side reactions, has been reviewed several tunes. Optimum yields are obtain widi bromine, followed by chlorine. Iodine gives acceptable yields provid diat the correct stoichiometry of 1 1 is used. The reaction is most frequently carried out in tetrachloromediane at reflux. From a practical pmnt of view, one drawback is the difficulty encountered in the preparation of dry silver caiboxylates the reaction of silver oxide on the acyl chloride in tetrachloromediane at reflux has been employed to circumvent diis problem. Evidendy the use of molecular bromine limits die range of functional groups compatible widi die reaction the different reaction pathways followed by the silver salts of electron poor (equation 19) and electron rich (equation 20) aryl carboxyl s illustrate this point well. 

This develops the general algorithm of calculation of minimum reflux mode for the columns with two feed inputs at distillation of nonideal zeotropic and azeotropic mixtures with any number of components. The same way as for the columns with one feed, the coordinates of stationary points of three-section trajectory bundles are defined at the beginning at different values of the parameter (L/V)r. Besides that, for the intermediate section proper values of the system of distillation differential equations are determined for both stationary points from the values of phase equihbrium coefficients. From these proper values, one finds which of the stationary points is the saddle one Sm, and states the direction of proper vectors for the saddle point. The directions of the proper vectors obtain linear equations describing linearized boundary elements of the working trajectory bundle of the intermediate section. We note that, for sharp separation in the top and bottom sections, there is no necessity to determine the proper vectors of stationary points in order to obtain linear equations describing boundary elements of their trajectory bundles, because to obtain these linear equations it is sufficient to have... 

Complete Fractionation Columns. A complete fractionation column, as shown in Fig. 6.11, may also be analyzed using the Ponchon-Savarit technique. In the McCabe-Thiele analysis, equations for two operating lines were found. These correspond to the A points in the Ponchon-Savarit analysis, where one A point represents the difference between passing streams in the column above the feed plate and the other A point represents the difference between passing streams below the feed plate. Assume that the reflux ratio, along with the composition and enthalpy of the feed, overhead distillate, and bottom product are known. Then points F, B, D, and A i may be located on... 

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