This presentation was originally published in Chemical Engineering Journal Advances.
- Authors:
- Talal A. Aldugman a, f, Mengmeng Cui a, Abdulrahman Alzailaie a, Abdullah Alhareth b, Kenneth Langley b, Lujain Alfilfil c, Khalid Almajnouni c, Jorge Gascon d, e, Sigurdur Thoroddsen b, Pedro Castaño a, e
- a Multiscale Reaction Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
- b Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
- c Advanced Materials and Catalysis Group, Aramco Research Center (ARC), Thuwal 23955-6900, Saudi Arabia
- d Advanced Catalytic Materials, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
- e Chemical Engineering Program, Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology, Saudi Arabia
- f SABIC Technology Center, Riyadh 11551, Saudi Arabia
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.