Advancing the promise of conical spouted beds for coarse particle processing

As an alternative to industrial fluidization for processing coarse particles, the “spouted bed” technique, which features a high-velocity central gas jet, emerged in the middle of the last century. Several geometries have been developed for the technique, but the conical spouted bed (CSB) — in which a high-velocity jet of gas enters a chamber, creating a spout that pushes particles up — has emerged as the most promising, especially for biomass pyrolysis and plastic recycling. However, because their dense, rapidly evolving internal flows are difficult to observe, there is a dearth of established CSB design methodologies.

Probing these hidden dynamics, Zhang et al. performed high-resolution supercomputer simulations to resolve the gas phase and track millions of individual particles. The results elucidate the fundamental physics governing gas–solid circulation across multiple CSB configurations.

“The specific solid kinetic energy, quantifying how effectively gas transfers momentum to particles, provides a superior indicator of reactor-scale performance compared with traditional static metrics such as bed height,” said author Feichi Zhang. “By mapping particle entrainment, upward spouting, and recirculation, we show design modifications, such as elevating the central draft tube or using porous tube walls, substantially intensify gas-solid mixing.”

The study demonstrated that CSBs exhibit markedly higher particle kinetic energy compared with conventional bubbling fluidized beds. But there is a key trade-off: CSBs demand higher mixing energy input and more complex hardware, yet their strong momentum exchange yields exceptional robustness with minimal heat and mass transfer limitations.

The researchers also identified acoustic resonances in the flow, offering diagnostic signatures for CSB monitoring and operational control.

“By translating microscopic hydrodynamics into actionable design principles, this work establishes a foundation for optimizing and scaling high-efficiency CSB reactors for advanced recycling and clean energy conversion,” said Zhang.

Source: “Numerical analysis of hydrodynamics in conical spouted bed reactors,” by Feichi Zhang, Xiaodi Dai, Muhao Li, Salar Tavakkol, and Dieter Stapf, Physics of Fluids, (2026). The article can be accessed at https://doi.org/10.1063/5.0327700 .