Periodic Operation of Three — Phase Catalytic Reactors

Abstract

Periodic operation of three phase reactors has been explored for more than two decades. This type of forcing changes selectivity and can increase either conversion or throughput. Experiments and simulation demonstrate periodic flow interruption or variation enhances reaction rates for concurrent trickle beds provided reactants are in the gas phase or can be volatilized under bed operating conditions. Temperature excursions in trickle beds can be controlled by either flow variation or switching the feed between an inert and a reactant. Several approaches to increasing rate through faster mass transfer using flow pulsing have been studied. Pulsing flow can be induced by low amplitude modulation. Periodic switching of flow direction in airlift reactors increases gas hold up and thereby the mass transfer rate. Periodic operation of three phase reactors, thus, appears to be a fertile area for engineering research.

Comparison of different reactor types for low temperature Fischer–Tropsch synthesis: A simulation study

“…On the other hand, pressure drop would increase at the same time. External mass transfer of the FBR in the trickle-flow regime may be improved by periodic operation (Silveston and Hanika, 2004). However, unsteady-state operation of mega-size commercial FTS reactors is hard to imagine.…”

Study of Unsteady‐State Operation of Methanation by Modeling and Simulation

“…Unsteady-state reactor operation was widely studied in past decades, aiming at improving the process performance by forced periodic modulation of the inlet composition, flow, pressure, or temperature [13][14][15]. The non-linearity of the reaction rates and the complexity of the reaction system are considered to be responsible for the differences between steady-state and unsteady-state operation [15].…”

Control of molecular weight distribution of polyethylene in gas-phase fluidized bed reactors

“…In fact, the broadening of the distribution can only be achieved by varying X periodically during the polymerization reaction. The implementation of periodic operation improves process performance and product properties and this has been the subject of many experimental and theoretical studies [17,20,[32][33][34][35][36][37].…”