FCC Riser Hydrodynamics Improvement Using Simulation Tools
Process Development Symposium
2013
2013 Process Development Symposium
General Program
Case Studies
Thursday, June 13, 2013 - 1:00pm to 1:30pm
Past experiences of commercial FCC units indicate that hydrodynamics have a pronounced effect on the riser performance. For example, an increase of lift steam velocity has been shown to result in increased gasoline selectivity in many units. For a large FCC unit in Asia the installation of dual-radii feed distributors improved feed-catalyst contacting in the lower riser and also led to better gasoline yields.
A study of FCC riser hydrodynamics was undertaken to understand the phenomena observed in the field. It encompassed computational fluid dynamics (CFD), cold flow modeling, radioactive tracer studies, kinetic modeling and yield estimation. The ultimate goal of the study was to isolate the effects of riser diameter, lift steam velocity, and solids flux on the hydrodynamic behavior and yield performance of FCC risers.
Our CFD approach was successfully validated by cold flow results and applied to several commercial FCC units. The general trends of riser hydrodynamics were identified as follows. Lower vapor velocity, larger riser diameter and higher solids flux through the riser all contribute to hydrodynamic “pathologies”, such as catalyst downflow at the wall and vapor channeling through the core of the riser. In practice, these “non-idealities” lead to “under-conversion” of feed in the core of the riser and overcracking of products in the annulus of the riser.
Checkout
This paper has an Extended Abstract file available; you must purchase the conference proceedings to access it.
Do you already own this?
Log In for instructions on accessing this content.
Pricing
Individuals
AIChE Pro Members | $895.00 |
AIChE Graduate Student Members | $895.00 |
AIChE Undergraduate Student Members | $895.00 |
AIChE Explorer Members | $1095.00 |
Non-Members | $1095.00 |