Stability and multiplicity approach to the design of heat-integrated PFR

The nonlinear behavior of the heat-integrated plug-flow reactor; consisting of a feed-effluent hear exchanger (FEHE) furnace, adiabatic tubular reactor, and steam generator is studied considering a first-order irreversible, exothermic, adiabatic reaction. Bifurcation theory is used to analyze the relationships among design, reaction thermodynamics and kinetics, and state multiplicity and stability. Hysteresis, isola and boundary limit varieties are computed, and the influence of the activation energy, reaction heat and FEHE efficiency on the multiplicity region is studied. The double-Hopf and double-zero bifurcation points divide parameter space in regions with different dynamic behavior. State multiplicity, isolated branches, and oscillatory behavior may occur for realistic values of model parameters. A design procedure is proposed to ensure a desired multiplicity pattern and a stable point of operation and to avoid high sensitivity. The procedure was applied to three reaction systems with different kinetic and thermodynamic characteristics.