Advanced Short Contact Time Reactors for Catalytic Processes


CounterDowner™ is a gas-solid reactor in which the catalyst falls while the gas rises. This counter-current contact raises solids holdup and breaks particle clusters, which gives a more uniform contact time than conventional risers and co-current downers [211, 181] [patent 04, 08, 09]. The platform has been developed from laboratory rigs to scaled-up units, supported by computational and experimental design tools.

  • Hydrodynamics, solids flux, and residence-time control [211, 184, 181, 209]
  • Coupling with a riser and regenerator for continuous operation [184] [patent 03]
  • Application to direct crude-to-chemicals cracking [206, 177, 162, 104] [patent 05, 06, 12]
  • Multifunctional fluidized-bed concepts for process intensification [171] [patent 18]

Related People

Mengmeng Cui
Muhammed Ikbal Arikan
Talal Aldugman

Related Publications

Comparative analysis of counter-current and co-current downer reactors using particle image velocimetry and computational particle-fluid dynamics

by Aldugman, Cui, Alzailaie, Alhareth, Langley, Alfilfil, Almajnouni, Gascon, Thoroddsen, Castaño
Chem. Eng. J. Adv. Year: 2025 DOI: https://doi.org/10.1016/j.ceja.2024.100687

Abstract

We investigated the hydrodynamics in co- and counter-current downer operations using particle image velocimetry (PIV) and computational particle fluid dynamics simulations (CPFD). Pilot-scale experiments were conducted for fluid catalytic cracking (FCC) catalysts and sand, which verified the system stability and provided the validation basis for the simulation strategy. We compared the reactor characteristics of counter-current and co-current downers under different operating modes and conditions using PIV experiments and CPFD simulations. PIV experiments showed that the counter-current downer exhibits a more uniform particle velocity profile, with a gradient of only 8 % of the maximum velocity, compared to the co-current operation, which shows a significantly steeper gradient of 39.5 % from the maximum. Simulations confirmed that the counter-current downer reactor has 69 % higher solid holdup and 98 % longer residence time than the co-current operation. Thus, the counter-current downer reactor demonstrated intermediate behavior between the classical co-current downer and riser reactors, offering flexibility for industrial applications.

Keywords

C2C FCC MKM CRE