Multiple Steady States in a Continuous Stirred-Tank Reactor 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. Some solutions are stable, others are unstable, and some can exhibit sustained oscillations or limit cycles. The steady-state operating conditions for the reactor depend on how the reactor is started 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; you can change the initial temperature with a slider. The second phase plane plots conversion versus temperature for one set of initial conditions, and you can vary both the initial temperature and the initial concentration . Temperature and conversion are also shown as a function of time in separate plots for these initial conditions. The steady-state solutions change as you vary the residence time , and limit cycle behavior is observed for residence times greater than about 30 minutes. The last plot (energy versus temperature) 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.