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Reactors Flow Reactors Mixed Flow Reactors (MFR) Continuous Stirred Tank Reactors (CSTR) Back Mixed Reactors (BM) Plug Flow Reactors (PFR) Batch Reactors

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Text of Reactors Flow Reactors Mixed Flow Reactors (MFR) Continuous Stirred Tank Reactors (CSTR) Back Mixed...

  • Batch Reactors

  • CharacteristicsReactor is charged via two holes in the top of the tank; While reaction is carried out, nothing else is put in or taken out until the reaction is done; Tank easily heated or cooled by jacket .This type are used for a variety of process operations.A typical batch reactor consists of a tank with an agitator and integral heating/cooling system. These vessels may vary in size from less than 1 liter to more than 15,000 liters .They are usually fabricated in steel, stainless steel, glass lined steel, glass or exotic alloy .

  • Kinds of Phases PresentGas phaseLiquid phaseLiquid-Solid

    CEB MKII Batch Reactor

  • UsageSmall scale productionIntermediate or one shot productionPharmaceuticalFermentationSolids dissolutionProduct mixingChemical reactionsBatch distillationCrystallizationLiquid/liquid extractionPolymerization

  • AdvantagesHigh conversion per unit volume for one passFlexibility of operation - same reactor can produce one product at a time and different product the nextEasy to clean

    DisadvantagesHigh operating costProduct quality more variable than with continuous operation

  • Sequential Batch Reactors (SBR)

  • Carbon Steel or Stainless Steel Reactors

  • Stainless steel reactors for chemical plant

  • "Glass Lined Reactors"

  • Reaction Vessel (Reactor)

  • Continuous Stirred Tank Reactors (CSTR)

  • CharacteristicsRun at steady state with continuous flow of reactants and products; The feed assumes a uniform composition throughout the reactor; Exit stream has the same composition as in the tank.

  • Kinds of Phases PresentLiquid phaseGas-liquid reactionsSolid-liquid reactionsUsageWhen agitation is requiredSeries configurations for different concentration stream.CEM MK II CSTR

  • AdvantagesContinuous operationGood temperature controlEasily adapts to two phase runsGood controlSimplicity of constructionLow operating (labor) costEasy to cleanDisadvantagesLowest conversion per unit volumeBy-passing and channeling possible with poor agitation

  • Batch reactorSemi-Batch reactor

  • Stirred contained solids reactors

  • Plug Flow Reactors(PFR)

  • CharacteristicsArranged as one long reactor or many short reactors in a tube bank ; No radial variation in reaction rate (concentration); Concentration changes with length down the reactor.Kinds of Phases PresentPrimarily Gas Phase

  • UsageLarge ScaleFast ReactionsHomogeneous ReactionsHeterogeneous ReactionsContinuous ProductionHigh Temperature

  • AdvantagesHigh conversion per unit volumeLow operating (labor) costContinuous operationGood heat transferDisadvantagesUndesired thermal gradients may existPoor temperature controlShutdown and cleaning may be expensive

  • Tubular reactor

  • Plug-flow reactors for Biomass Conversion

  • Industrial scale Reactor

  • Homogeneous Continuous Reactions (Plug Flow)

  • Reactive Distillation - Homogeneous

  • Reactive Distillation - Heterogeneous

  • creating plug-flow conditions in reactors

  • Fixed bed reactors

  • Fischer-Tropsch reaction convert synthesis gas into a mixture of alkanes and alkenes over Fe catalyst.Fluidized bed reactor

  • Four major chemical reactorsin petroleum refining


  • Process Design

  • Matters for Design ConsiderationType of processing Batch Continuous Semibatch or semicontinuous Type and nature of reacting system Simple Complex (desirable,, undesirable products) Stoichiometry Phases, number of phases Catalytic (choice of catalyst) or noncatalytic Endothermic or exothermic Possibility of equilibrium limitation

  • Cont.Type and size of reactor Batch Continuous (stirred tank , tubular, tower/column, bed )Mode of operationConfigurational (single-stage or multistage , axial or radial flow, arrangement of heat transfer surface, flow pattern, contacting pattern) Thermal (adiabatic, isothermal , nonisothermal, nonadiabatic) Use of recycle

  • Cont..Process conditions T profile P profile Feed (composition, rate) Product (composition, rate) Optimality of process conditions of size of product distribution of conversion of cost (local, global context)

  • ContControl and stability of operation Instrumentation Control variables Sensitivity analysis Catalyst life, deactivation, poisons Socioeconomic Cost Environmental Safety Materials of constructional corrosionStartup and shutdown procedures

  • Data Required SpecificationsReactants Products Throughput or capacity general dataRate data/parameters relating to reaction (rate law/s, heat transfer, mass transfer, pressure drop, equilibrium data, other physical property data, cost data)

  • Tools Available The rational design of a chemical reactor is perhaps the most difficult equipment-design task of a chemical engineer.

    Rate processes and rate laws Reaction kineticsDiffusion and mass transferHeat transferFluid mechanics (flow patterns , mixing, pressure drop)Conservation and balance equations Mass balances (including stoichiometry)Continuity equation Energy balance (including energetics of reaction)Thermochemistry

  • Cont.Equilibrium Reaction equilibriumPhase equilibriumMathematics Development of a reactor modelAnalytical or numerical methods for solution of equationsSimulation statistical analysis of rate data

  • Cont..Computers and computer software Use of a PC, workstations, etc., coupled with software packages to solve sets of algebraic and/or differential equations, and to perform statistical analyses necessary for implementation of a reactor model for design or for assessment of reactor performance Software (spreadsheet packages, simulation software, numerical equation solvers, computer algebra system) Process economics

  • Mechanical Design Impeller or agitator design (as in a stirred tank) Power requirement (for above) Reactor-as-pressure-vessel designWall thickness Over-pressure relief Fabrication Support-structure design Maintenance features

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