化学反应工程Chapter 5.ppt

Mixed Flow Reactor 化 学 反 应 工 程 SOLUTION Let A = PH3, R =P4 , S = H2. Then the reaction becomes 4A R + 6S with The volume of plug flow reactor is given by Eq.20 Evaluating the individual terms in this expression gives FA0 = 40 mol/hr 化 学 反 应 工 程 = hence the volume of reactor k = 10/ hr 化 学 反 应 工 程 EXAMPLE 5.6 TEST OF A KINETIC EQUATION IN A PLUG FLOW REACTOR We suspect that the gas reaction between A, B, and R is an elementary reversible reaction A + B R and we plan to test this with experiments in an isothermal plug flow reactor. Develop the isothermal performance equation for these kinetics for a feed of A, B, and inerts. (b) Show how to test this equation for an equimolar feed of A and B. 化 学 反 应 工 程 SOLUTION Feed pf A, B, and inerts. For this elementary reaction the rate is At constant pressure, basing expansion and conversion on substance A, Let M = CB0/CA0 , M′= CR0/CA0, we obtain 化 学 反 应 工 程 Hence, the design equation for plug flow, Eq.17, becomes In this expression accounts for the stoichiometry and for inerts present in the feed. (b) Equimolar feed of A and B. For CA0 =CB0 , CR0 = 0, and no inerts, we have M=1, M′= 0, εA= －0.5; hence the expression for part a reduces to 化 学 反 应 工 程 EXAMPLE 5.2 KINETICS FROM A MIXED FLOW REACTOR Pure gaseous reactant A (CA0 = 100 millimol/ liter) is fed at a steady rate into a mixed flow reactor (V = 0.1 liter) where it dimerizes (2A R). For different gas feed rates the following data are obtained: Run number 1 2 3 4 10.0 3.0 1.2 0.5 millimol/liter 85.7 66.7 50 33.4 Find a rate equation for this reaction. 化 学 反 应 工 程 SOLUTION For this stoichiometry, 2A R, the expansion factor is and the corresponding relation between concentration and conversion is or 化 学 反 应 工 程 The conversion for each run is then calculated and tabulated in column 4 of