Thermoflow multiplicity in nonadiabatic multitube reactors
Steady states with different flow rates and temperature profiles may exist in a multitube packed-bed reactor operating under a prescribed pressure drop due to the coupling among the species, energy and momentum balances, and the dependence of physical properties on temperature, composition, and pressure. This thermoflow multiplicity may lead to a highly undesired operation. A pseudohomogeneous nonadiabatic one-dimensional reactor model is used to predict the conditions under which the multiplicity may exist when a single gaseous exothermic reaction is carried out. Two limiting models,one assuming negligible dispersion of heat (ND) and one assuming infinite dispersion (lumped thermal or LT), as well as a general model accounting for finite thermal dispersion (FD) are analyzed. Each limiting model is analyzed for several limiting cases, each assuming that a different mechanism is the main cause of pressure drop. When the thermal axial dispersion is neglected, thermoflow multiplicity may be observed only for highly exothermic reactions, even if the reaction induces a volume increase. The FD model exhibits multiplicity for larger heats of reaction than those of the LT model but smaller than those of the ND model. These values span the range of interest for industrial reactors.
- Research Organization:
- Houston Univ., TX (USA)
- OSTI ID:
- 5205138
- Country of Publication:
- United States
- Language:
- English
Similar Records
Increase productivity with novel reactor design
Analytical criteria for validity of pseudohomogeneous models of packed-bed catalytic reactors