Fixed bed catalytic reactor modelling: The heat transfer problem

A multidimensional heterogeneous and dynamic model of a fixed-bed heat exchanger reactor used for CO2 methanation has been developed in this work that is based on mass, energy and momentum balances in the gas phase and mass and energy balances for the catalyst phase. The dynamic behavior of this reactor is simulated for transient variations in inlet gas temperature, cooling temperature, gas inlet flow rate, and outlet pressure. Simulation results showed that wrong-way behaviors can occur for any abrupt temperature changes. Conversely, temperature ramp changes enable to attenuate and even fade the wrong-way behavior. Traveling hot spots appear only when the change of an operating condition shifts the reactor from an ignited steady state to a non-ignited one. Inlet gas flow rate variations reveal overshoots and undershoots of the reactor maximum temperature. © 2017 American Institute of Chemical Engineers AIChE J, 64: 468–480, 2018

Dynamic modeling and simulations of the behavior of a fixed-bed reactor-exchanger used for CO2 methanation

/pdf/mathematical-modeling-of-catalytic-fixed-bed-reactors-45vp366ehy.pdf

Mathematical modeling of catalytic fixed bed reactors

The generalized parametric sensitivity criterion was used to obtain runaway diagrams for one- and two-dimensional heterogeneous models and a one-dimensional pseudo-homogeneous model. The simulation work was based on the partial methanol oxidation to formaldehyde, which occurs in a fixed-bed reactor, with two distinct catalytic zones. At the inlet of the reactor, the catalyst was diluted with inert packing followed by a region with pure catalyst. This activity profile induces a reduction in the parametric sensitivity of the process to temperature runaway, when compared to a uniform activity bed, and the sensitivity functions reach a minimum when the inlet temperature is in the range of 530−540 K. The dilution of the catalytic bed leads to an enlargement of the stable region of operation, which allows a gain in the critical methanol concentration of 20% for a feed temperature of 530 K (industrial operating temperature), higher gains being possible (∼40%) for higher inlet temperatures. Moreover, depending on...

/pdf/thermal-runaway-conditions-of-a-partially-diluted-catalytic-21r1r6pv44.pdf

Thermal Runaway Conditions of a Partially Diluted Catalytic Reactor

Experimental study of ignition and extinction waves and oscillatory behavior of a tubular nonadiabatic fixed bed reactor for the oxidation of carbon monoxide

J. Puszyński

Papers

A Revision of multiplicity and parametric sensitivity concepts in nonisothermal nonadiabatic packed bed chemical reactors