Systemic design of heat integrated plug-flow reactor. Application of bifurcation theory

COSTIN S. BILDEA and ALEXANDRE C. DIMIAN
Department of Chemical Engineering,
University of Amsterdam, The Netherlands

Mailing address: Nieuwe Achtergracht 166
1018 WV Amsterdam
The Netherlands
e-mail: [email protected]
[email protected]

Keywords: Process System Engineering, Process Dynamics, Integrated Design and Control, Bifurcation Theory

ABSTRACT

In this article we study the non-linear behaviour of the heat-integrated plug flow reactor, consisting of feed-effluent heat exchanger (FEHE), furnace, adiabatic tubular reactor and steam generator. We focus on the relationship between the design and thermodynamic and kinetic characteristics of the reaction. A first order, irreversible, exothermic, adiabatic reaction is considered. The steady state multiplicity and stability are analysed using bifurcation theory. We calculate the hysteresis, isola and boundary limit varieties and study the influence of the activation energy, reaction heat and FEHE efficiency on the multiplicity region. Dynamic classification is achieved by the computation of the double Hopf and double zero bifurcation points. State multiplicity, isolated branches and oscillatory behaviour 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.

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Figures

Figure 1. Heat integrated PFR.
Figure 2. Conversion vs. furnace duty for different values of NTU.
Figure 3. Swallowtail bifurcation.
Figure 4. Cross section of the hysteresis variety in (g,B) plane.
Figure 5. Phase diagram heat-integrated PFR with FEHE efficiency as bifurcation parameter.
Figure 6. Conversion vs. FEHE efficiency bifurcation diagrams.
Figure 7. Phase diagram of heat-integrated PFR with energy input as bifurcation parameter.
Figure 8. Conversion vs. energy input bifurcation diagrams.
Table 1. Design results for three heat integrated PFR systems.