化学反应工程Chapter 5-new.ppt

The Mixed Flow Reactor, or MFR ( Fig.5.1c) EXAMPLE 5.1 REACTION RATE IN A MIXED FLOW REACTOR One liter per minute of liquid containing A and B (CA0 = 0.10 mol/ liter, CB0 = 0.01 mol/ liter) flow into a mixed reactor of volume V = 1 liter. The materials react in a complex manner for which the stoichiometry is unknown. The outlet stream from the reactor contains A, B and C ( CAf = 0.02 mol/ liter ,CBf = 0.03 mol/ liter ,CCf = 0.04 mol/ liter as shown in Fig.E5.1. Find the rate of reaction of A, B and C for the conditions within the reactor. Chemical Reaction Engineering Figure E5.1 Chemical Reaction Engineering SOLUTION For a liquid in a mixed flow reactor ?A = 0 and Eq.13 applies to each of the reacting components, giving for the rate of disappearance: Thus A is disappearing while B and C are being formed. Chemical Reaction Engineering 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. Chemical Reaction Engineering SOLUTION For this stoichiometry, 2A ? R, the expansion factor is and the corresponding relation between concentration and conversion is or Chemical Reaction Engineering The conversion for each run is then calculated and tabulated in column 4 of Table E5.2. Table E5.2 log CA log (-rA) 2 3.0 66.7 0.50 1500 1.824 3.176 3 1.2 50 0.667 800 1.699 2.930 4 0.5 33.3 0.80 400 1.522 2.602 Calculated Chemi