Analysis of fluidization quality of a fluidized bed with staged gas feed for reactions involving gas‐volume reduction

Abstract

A significant defluidization occurs when carrying out reactions involving a decrease in gas volume in a fluidized catalyst bed. The cause of this phenomenon is a decrease in the gas velocity in the emulsion phase below the minimum fluidization velocity. Fluidization quality is improved by a staged gas feed when hydrogenation of CO 2 is carried out. To evaluate the experimental results, two parameters are introduced; gas-volume reduction rate and gas-volume ratio. Fluidization quality and defluidization zone are indicated as a map using these parameters. The vertical distributions of these parameters are calculated using a reactor model to obtain operating lines. The calculation shows that fluidization quality can be improved by operating the reactor by avoiding the operating lines of the defluidization zone in the map. For this purpose, it is required to control the gas-volume ratio at a level near unity and maintain the gasvolume reduction rate below 0.01/s.

Novel hierarchical Ni/MgO catalyst for highly efficient CO methanation in a fluidized bed reactor

“…In addition, most of the aforementioned catalysts have been developed on the basis of fixed‐bed methanation reactors. However, the fluidization quality and attrition strength of the nanosized catalysts in fluidized‐bed reactors are critical for obtaining high reactivity and a long lifespan, especially for the highly exothermic methanation reaction accompanied by a large decrease in gas volume . Therefore, it is important to develop a highly active catalyst that is not only stable against sintering and carbon deposition but also able to fluidize sufficiently in fluidized‐bed reactors.…”

Enhanced Methanation over Aerogel NiCo/Al2O3Catalyst in a Magnetic Fluidized Bed

“…The CO methanation reaction (CO + 3H 2 → CH 4 + H 2 O) is a highly exothermic reaction accompanied by a large decrease in stoichiometry. , One of the key issues of the methanation was to remove the reaction heat to avoid the high temperature sites . The catalytic activity of the Ni catalysts is decreased due to the sintering of the Ni particles and carbon deposition that are induced at these high temperature sites. , Since the 1950s, much work has been carried out to investigate the excellent methanation reactors (include fixed bed reactors, fluidized bed reactors, slurry reactors) that try to overcome these problems. − …”

“…However, the nanosized catalysts are difficult to fluidize in a fluidized bed reactor. The inherent large gas-volume decrease in the methanation reaction makes a steady fluidization it more difficult, which induces poor-quality products and safety problems in the fluidized reactor. , Therefore, enhanced fluidization of the fine catalyst particles is the key topic for the fluidization methanation process.…”