Chapter 4 REACTOR DESIGN FOR MULTIPLE REACTIONS Single reactions + + − = Because of • high and − • small PFR BR Single reactions Conversion Multiple reactions Selection Conversion Parallel reactions − = − = = − − = > Because of • high and • small • and are contravariant < Because of • low • high • and are covariant PFR CSTR BR = 1− Parallel reactions + + − = − = = − − = > > Because of • high , and • small > < Because of • low • high and PFR BR Semi BR Semi PFR = 1− − Parallel reactions + + − = − = = − − = < < Because of • low , • high < > Because of • low • high and Semi BR Semi PFR CSTR = 1− − Series reactions − = − = = − − = Because of • high and • high • and are contravariant PFR BR Complex reactions − = − = − = > Because parallel and series reactions are also require the BR and PFR < PFR BR Semi PFR PFR PFR CSTR PFR CSTR Polymerization reactions Polymerized by functional groups Polymerized by free radical Polymer has a narrow distribution of molar mass because of the same residence time Polymer has a wide distribution of molar mass because the monomer and free radical concentrations decline Polymer has a wide distribution of molar mass because of different residence time Polymer has a narrow distribution of molar mass because the monomer and free radical concentrations are maintained PFR BR CSTR PFR BR CSTR Biochemical reactions Promoted by microorganisms Promoted by enzymes + − = + The reaction rate is the same to the autocatalytic reactions, reactor depends on − = + Because of high , PFR CSTR PFR BR CSTR PFR CSTR Conclusion of multiple reactions If and are contravariant: • ≈50%in irreversible reactions • ≈50% in reversible reactions If and are covariant: • ≈95%in irreversible reactions • ≈95% in reversible reactions [...]...Single reversible reactions The effect of feed ratio on equilibrium conversion Single reversible reactions The effect of inert material on equilibrium conversion Parallel reactions + + − − = = = Semi BR − > − Excess Semi PFR Semi BR − < − Excess Semi PFR Parallel reactions + + ∆ < + + = − − = − Concentrations of inert... Series reactions − − = = BR + PFR − = − Semi BR Semi PFR = = Because of • low and high = Excess because of • low • high and Removal • low Series reactions − − = = CSTR = − PFR − Removal • low • shift equilibrium Concentration of inert and are covariant ∆ < Concentration of inert and are contravariant ∆ > Recycling undesired Use one reactant in excess for parallel reactions. .. reactions Maximize = − − + > < − − , use excess , use excess + + Decrease concentration of inert Increase concentration of inert Reactor Separator Reactor Product Separator + + Reactor Separator + Feed + Product Change Mixing characteristics Temperature Pressure Catalyst Product +