化工原理课件PPT.ppt

Chapter 6.;Equimolal diffusion; The concentration gradient for A is linear in the film, and the gradient for B has the same magnitude but the opposite sign ;one-way diffusion;6.2 Prediction of Diffusivities;The Chapman-Enskog equation for binary diffusion;Diffusion in liquids;Two-Film Theory;Chapter7.;7.1.1 gas-liquid equilibrium;7.1.2 Vapor-Liquid Equilibrium Relations;Equilibrium relation;Relative Volatility of Vapor–Liquid Systems; For a separation process in which α =1, the compositions of component A would be the same in both phases, separation is not possible when this occurs since the driving force for mass transfer is zero. When the value of α is above 1, a separation is possible. The value of α may change as concentration and total pressure change. ;Boiling-Point Diagrams and x-y Plots;maximum boiling azeotrope minimum boiling azeotrope;7.2. Equilibrium-Stage Operations;Material balances and operating line;Ideal contact stages;Determining the number of ideal stages;Absorption factor method for calculating the number of ideal stages;When the operating and equilibrium lines are both straight over a given concentration range xa to xb, the number of ideal stages can be calculated directly;(7.2-22);When the operating line and the equilibrium line are parallel,;Chapter 8;8.1.1 Material balances;In many instances more convenient expressions can be derived for evaluating the absorption process if a solute-free basis is used for compositions rather than mole fractions.;8.1.2 Limiting and Optimum Gas-liquid Ratio;In general, the liquid rate for the absorber should be between 1.1 and 2.0 times the minimum rate, unless the liquid is to be discarded and not regenerated;8.1.3. Rate of absorption in packed towers;controlling resistance gas phase is controlling liquid phase is controlling;8.2 Calculation of tower height;8.2.2 Number of transfer units and height of a transfer unit;number of transfer units NOy.;For straight operating and equilibrium lines, the number