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 reacto r, and steam generator is studied considering a first-order irreversible, e xothermic, adiabatic reaction. Bifurcation theory is used to analyze the re lationships among design, reaction thermodynamics and kinetics, and state m ultiplicity and stability. Hysteresis, isola and boundary limit varieties a re 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 diffe rent dynamic behavior. State multiplicity, isolated branches, and oscillato ry behavior may occur for realistic values of model parameters. A design pr ocedure is proposed to ensure a desired multiplicity pattern and a stable p oint of operation and to avoid high sensitivity. The procedure was applied to three reaction systems with different kinetic and thermodynamic characte ristics.