Fluidized Bed: Two-Phase Bubble Population

Fluid Catalytic Cracking (FCC) units suspend a zeolite catalyst in an upward stream of hot hydrocarbon vapor. This is the same Wen–Yu minimum-fluidization physics and Voorhies coking kinetics as the 3D reactor sim, but seen through its cross-section instead of a rendered vessel: the bubbling gas phase is simulated as a genuine two-phase-theory bubble population — bubbles nucleate at the distributor, grow with height by the Mori–Wen correlation, rise at their own Davidson–Harrison velocity, and coalesce when they meet — so the bed-expansion ratio you read off is computed directly from that live bubble fraction δ, not a preset visual curve. Drag the gas velocity past U_mf to watch the bubble population appear and grow, and track how coke deposition steadily deactivates the same catalyst until you regenerate it.