CHN-204 Reaction Engineering Graphical representations for Multiple Reactions & Denbigh reactions Dr. Hari Prakash Veluswamy Assistant Professor Depar tment of Chemi cal Engineering IIT Roor kee 22 February 2023 Multiple reactions • Multiple reactions require more than one rate expression to determine kinetic behaviour • Types of Multiple reactions • Parallel • Series • Complex (Series-parallel) • Independent 2 Parallel reactions • For reactions in parallel, the concentration level of reactants is the key to proper control of product distribution • High reactant concentration favours the reaction of higher order • Low reactant concentration favours the reaction of lower order • Concentration level has no effect on the product distribution for reactions of same order 3 Series reactions Maximum possible amount of any and all intermediates is obtained if fluids of different compositions and at different stages of conversion are not allowed to mix 4 Series reactions in plug flow or batch reactor 5 Series reactions in plug flow or batch reactor 6 Series reactions in mixed flow reactor 7 Series reactions in mixed flow reactor 8 Comparison of series reactions in PFR Vs MFR 9 Series-parallel reactions in PFR or batch reactor 10 Series-parallel reactions in PFR or batch reactor 11 Series-parallel reactions in mixed flow reactor 12 Series-parallel reactions in mixed flow reactor 13 Example problem 14 Solution 15 Denbigh reactions 16 Denbigh reactions in PFR or batch reactor 17 Denbigh reactions in mixed flow reactor 18