Analysis of volume change effects in a fluidized bed catalytic reactor

Abstract

A mathematical model based on the concept of an improved bubble assemblage model is developed for calculating the conversion of a reaction system involving a volume change in fluidized beds. The influence of volume change on the hydrodynamic behavior of gas in the bed, such as bubble size variation, superficial gas velocity change, and volume fraction occupied by each phase, is also investigated. It is found that increasing stoichiometric coefficient values results in larger bubble size, higher superficial gas velocities, higher crossflow rate between emulsion phase and bubble phase, and greater volume fraction of bubble phase, but smaller volume fraction occupied by the emulsion phase as well as lower conversions.

Effect of volume decrease on fluidization quality of fluidized catalyst beds

“…Because the change in the gas volume accompanied by reactions influence the conversion and selectivity, these effects were previously considered in the fluidized‐bed reactor models 1–4. In the reactor models, the effects of the gas‐volume change were taken into account, such as the changes in bubble volume and bubble frequency.…”

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

“…Many industrial gas phase reactions involve a volume change that influences their conversion and selectivity. The effects of volume change on conversion in fluidized bed reactor models have been reported by some researchers 1–6. In addition, volume change can influence the hydrodynamic behavior of fluidized beds.…”

Effects of Increase in Gas Volume on the Fluidization Properties in Fluidized Bed Reactors

“…Although these reactions often involved the gas-volume changes, many reactor models did not take account of the gas-volume changes. On the other hand, some researchers have emphasized that it is important to consider the changes in the total number of moles due to reactions in the fluidized bed reactor-models (Irani et al, 1980;Corella and Bilbao, 1984;Kai and Furusaki, 1984;Shiau and Lin, 1993;Tafreshi et al, 2000;Abba et al, 2002).…”

“…In order to satisfy the overall material balance at a given bed height, the crossflow terms have been considered in the reactor models (Kai and Furusaki, 1984;Shiau and Lin, 1993;Tafreshi et al, 2000). Irani et al (1980) did not consider the crossflow, because they assumed that the extra gas generated went to form new bubbles.…”

“…In addition, they considered that the effective diameter of the bubbles remained constant. On the other hand, the bubble diameter was assumed to change according to the gas velocity with height by some researchers (Corella and Bilbao, 1984;Shiau and Lin, 1993;Al-Zahrani et al, 2001).…”