A reduced vapor pressure equation of the form In PR = a-+ /3/TRm + 7 7Rn has been applied to 113 nonpolar substances which include 95 hydrocarbons of all types and 18 inorganic substances. In this study the exponent n was taken to be 7.0, as established In an earlier study associated with the normal paraffins. The involvement of the critical point eliminates parameter a, requiring knowledge of the three parameters ß, y, and m. Relationships for these vapor pressure parameters have been developed and require for their establishment knowledge of the normal point, critical temperature, and critical pressure of the substance. Vapor pressures calculated with predicted parameters were compared with corresponding values reported in the literature to produce an average deviation of 0.97% (6290 points) for these 113 organic and inorganic substances. Whenever available, vapor pressure values between the critical point and the triple point were considered in these comparisons.

In a gas-liquid reactor, unreacted gas is often diluted with an inert so that a safe concentration is always maintained above the liquid phase. A conventional feedback control system which manipulates the diluent gas flow does not adequately maintain a safe and effective dilution if the process is subjected to a persistent stepwise disturbance, as for example, occurs in a batch operation, when the reaction rate falls off. In this paper, a feedback control algorithm which manipulates both the inert and reactant gas flows is presented. This control scheme gives very satisfactory performance for the semicontinuous or batch case.

The vapor pressure behavior of 25 polar compounds, iucluding water and a number of alcohols, has been analyzed and subjected to a generalized treatment using the relationship, for a total of 1343 experimental measurements presented in the literature and covering the range included between their respective triple points and critical points. For each of these compounds, the parameters of this equation were established using a nonlinear regression numerical technique. The parameters resulting from this regression reproduce vapor pressures for all these polar compounds with an average deviation of 0.44 percent (1 343 points).To extend the application of this vapor pressure relationship, the original parameters of these polar substances were correlated with their respective basic physical properties M, T,, P, and T,. The resulting generalized parameters reproduce vapor pressures with an average deviation of 1.44 percent (1343 points) for all these polar and hydrogen-bonding compounds. This generalized correlation can be applied for the reliable prediction of vapor pressures for polar substances for which inadequate information is available.Q Q v 1.44

Vapor-liquid equilibrium measurements have been carried out for the propane-ethanol system at 325O, 350°, 375O, 400°, and 425OK. The pressures corresponding to these temperatures ranged from 569.5 kPa (82.6 lb/ in.2abs) to 5 618.5 kPa (814.9 lb/in.Zabs). Altogether, nineteen experimental determinations were made; one of these determinations at 425OK approached the critical state, and this measurement assisted in establishing the entire critical temperature and critical pressure profiles for this binary system. The information associated with these measurements enabled the construction of isothermal bubble point-dew point relationships up to 50O0K. These results made possible the establishment of isothermal relationships of K values vs. pressure for the components of the propane-ethanol system.Calculated K values for this system using the BWR method and the SRK method were found to be in fair agreement with corresponding experimentd values.