Continuous Stirred Tank Reactors (CSTRs)

Chemical and Biological Reaction Engineering, Spring 2007 Prof. William H. Green Lecture 5: Continuous Stirred Tank Reactors (CSTRs) This lecture covers: reactions in a perfectly Stirred tank. Steady State cstr . Continuous Stirred Tank Reactors (CSTRs) Continuous Plug Flow Reactor cstr Open system Steady State Well mixed Open system Steady State Continuous Batch Close system Well mixed Transient In terms of conversion, XA? Mole Balance on Component A In-Out+Production=Accumulation FF(steady state) Ao +ArAV=0 What volume do you need for a certain amount of conversion? FXV=AoA rAwhere rA is evaluated at the reactor concentration. This is the same as the exit concentration because the system is well mixed. For a liquid phase with constant P: FC=( =volumetric flow rate) AoAov00vFFAo VF==AAFAo XAF rAoAFigure 2. A batch reactor. Figure 1. A plug flow reactor, and Continuous Stirred tank reactor. FCAA=v 0 VCX=AoA vr0 AV = average time a volume element of fluid stays in the reactor v0 Cite as: William Green, Jr.

AoA A CX r τ= − Consider: 1st Order Reaction Kinetics −=rkCAA concentration or conversion? Æ convert rate law from C A to X A CC XAAo A=−()1 −= −rkC XAAo()1 A ()11() Ao A A reactor size in terms of conversion and rate constant Ao A A CX X kC X k X τ ⎫⎪ ==⎬ −−⎪⎭ Æ rearrange to find how much conversion for a given reactor size

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  Tanks, Reactions, Continuous, Creator, Consider, Strider, Cstr, Continuous stirred tank reactor

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