Simulation study of gas-fluidized bed reactors with major changes in molar and volumetric flow

Abstract

Mechanistic models are commonly used to simulate gas-fluidized bed reactors. Gas is assumed to pass through two compartments in parallel, one a dilute phase and the other a dense phase containing most, or all of, the particles, as well as interstitial gas. Interphase mass transfer plays a key role, since most of the gas passes through the dilute phase, while most reaction occurs in the dense phase. For reactions with changes in molar gas flow, this creates a dilemma, as the extent to which, and rate at which, the change in volumetric flow is distributed between the phases are unclear. The results are especially important when there is a substantial decrease in volumetric flow that could cause defluidization of the dense phase. This paper considers steam methane reforming and its reverse reaction, methanation, to investigate two limiting cases where the molar gas flow greatly increases and decreases, respectively.