Fluidized Bed Reactor

Overview

The Fluidized Bed Reactor model simulates two-phase fluidized systems with bubble and emulsion phases. It is used for catalytic cracking, combustion, and polymerization processes where excellent heat and mass transfer characteristics are required.

Theory and Equations

Two-Phase Model

Bubble Phase:

\[\frac{dC_b}{dt} = K_{bc}(C_e - C_b) - u_b \frac{dC_b}{dz}\]

Emulsion Phase:

\[\frac{dC_e}{dt} = K_{bc} \frac{\delta_b}{1-\delta_b}(C_b - C_e) - k C_e \frac{\rho_{cat}(1-\epsilon_{mf})}{1-\delta_b}\]

Fluidization Properties

  • Minimum fluidization velocity: \(U_{mf}\)

  • Bubble velocity: \(u_b = u_g - U_{mf} + u_{br}\)

  • Bubble fraction: \(\delta_b = f(u_g, U_{mf}, geometry)\)

Key Features

  • Two-phase (bubble and emulsion) modeling

  • Fluidization regime characterization

  • Heat and mass transfer between phases

  • Catalyst circulation effects

  • Gas-solid contact modeling

Usage Example

from unit.reactor.FluidizedBedReactor import FluidizedBedReactor

# Create Fluidized Bed Reactor instance
reactor = FluidizedBedReactor(
    H=3.0,               # Bed height [m]
    D=2.0,               # Bed diameter [m]
    U_mf=0.1,           # Minimum fluidization velocity [m/s]
    rho_cat=1500.0      # Catalyst density [kg/m³]
)

Example Output

Fluidized Bed Reactor Example
==================================================
Reactor: Fluidized Bed Reactor
Bed Height: 3.0 m
Bed Diameter: 2.0 m
Minimum Fluidization Velocity: 0.1 m/s
Catalyst Density: 1500.0 kg/m³
Particle Diameter: 0.50 mm
Activation Energy: 60.0 kJ/mol

Operating Conditions:
Inlet concentration: 100.0 mol/m³
Inlet temperature: 700.0 K (426.9 °C)
Superficial gas velocity: 0.3 m/s
Coolant temperature: 650.0 K (376.9 °C)

Reactor is fluidized (U_g > U_mf)
Excess velocity: 0.200 m/s

Fluidization Properties:
Bubble velocity: 0.250 m/s
Bubble fraction: 0.801
Emulsion fraction: 0.199

Performance Plots

Dynamic Response (fluidized_bed_reactor_example_plots.png)

Fluidized bed reactor bubble and emulsion phase dynamics

Applications

  • Fluid catalytic cracking (FCC)

  • Coal combustion and gasification

  • Polymerization processes

  • Roasting and calcination

  • Waste treatment

See Also