07-Lect-Stoichiometry Tables0

07-Lect-Stoichiometry Tables0 - 1 Chemical Reaction...

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Unformatted text preview: 1 Chemical Reaction Engineering - Musgrave Stoichiometry Tables and Kinetics Lecture 7 - Page 1 Outline: 1. Stoichiometry and Batch Reactors (Fogler 3.5) 2. Stoichiometry and Flow Reactors(Fogler 3.6) Next Time: (Fogler 4.1-4.2) 1. Design Structure for Isothermal Reactors (Fogler 4.1) 2. Scale-Up of Liquid-Phase Batch Reactor Data for CSTR Design (Fogler 4.2)) Stoichiometry Tables and Kinetics Lecture 7 - Page 2 Consider the gas phase Diels Alder reaction: C 4 H 6 +C 2 H 4 C 6 H 10 that is 2 nd order. What size CSTR and PFRs would be required to achieve 60% conversion of a stream of 28 mol/hr of C 4 H 6 and 72 mol/hr C 2 H 4 ? Levenspiel Plot 1 2 3 4 5 6 7 8 9 10 11 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 X-F_A/r_A F A r A V = F A dX r A X V CSTR = F A X r A We need to the rate in terms of conversion! r A = r A X ( ) 2 Chemical Reaction Engineering - Musgrave Stoichiometry Tables and Kinetics Lecture 7 - Page 3 To size CSTRs and PFRs for a reaction: aA+bB cC+dD V PFR = F A dX r A X V CSTR = F A X r A We use the design equations : r A = r A X ( ) And so we need r A (X): But, what we might have is the rate law, for example: r A = k A C A 2 X ( ) Along with the rate constant: k A = A exp E A RT ( ) So to get-r A (X) we need to obtain the concentrations in terms of X. To keep track of how X affects C i for all species we use a stoichiometry table. Of course, reaction (conversion) can change C i in various ways: 1. Changing n i . 2. Changing V. 3. Changing total number of moles of gas phase species. 4. Changing T and/or P. Chemical Reaction Engineering - Musgrave Stoichiometry Tables and Kinetics Lecture 7 - Page 4 We can use expressions weve already worked out to create a stoichiometry table for the general reaction aA+bB cC+dD carried out in a batch reactor. Species Intially (mol) Change (mol) Remaining (mol) A N A N A X ( ) N A = N A N A X B N B b a N A X ( ) N B = N B b a N A X C N C c a N A X ( ) N C = N C + c a N A X D N D d a N A X ( ) N D = N D + d a N A X I N I _ N I Totals N T N T = N T + c a + d a b a 1 N A X = c a + d a b a 1 N T = N T + N A X y Highlighted entries are specified and others are calculated But, what we really want is C i (X)! 3 Chemical Reaction Engineering - Musgrave Stoichiometry Tables and Kinetics Lecture 7 - Page 5 c a + d a b a 1 i N i N A To include C i (X) we add a column with N i /V! Species Intially Change Remaining Concentration A N A N A X ( ) N A = N A (1 X ) N A V (1 X ) B N B b a N A X ( ) N B = N A ( B b a X ) N A V ( B b a X ) C N C c a N A X ( ) N C = N A C + c a X N A V C + c a X D N D d a N A X ( ) N D...
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This note was uploaded on 04/25/2010 for the course CHEN 4330 taught by Professor Staff during the Spring '08 term at Colorado.

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07-Lect-Stoichiometry Tables0 - 1 Chemical Reaction...

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