Multiple Steady States in CSTR with Heat Exchange
Under certain conditions, an exothermic reaction in a continuous stirred-tank reactor (CSTR) with heat exchange can exhibit multiple steady-state solutions. Solutions can be stable, unstable, or exhibit sustained oscillations or limit cycles. The steady-state operating conditions depend on how the reactor starts up (initial conditions). The first phase plane plot shows reactant concentration versus reactor temperature, as a function of time, as the reactor approaches a steady state (or a limit cycle) for five initial concentrations; the initial temperature, To, is changed with a slider. The second phase plane plots conversion versus temperature for one set of initial conditions; both the initial temperature and the initial concentration Co can be changed. Selecting the two buttons on the right show plots of temperature and conversion as a function of time for these initial conditions. The steady-state solutions change as the residence time \( \left( \tau \right) \) changes, and limit cycles are observed for \( \tau \) greater than about 30 min. The energy versus temperature plot shows heat generated and heat removed as a function of temperature, and the intersections of these two curves correspond to steady-state solutions to the mass and energy balances for the CSTR.
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This simulation was made at the University of Colorado Boulder, Department of Chemical and Biological Engineering. Author: Rachael L. Baumann
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