(54aa) Dpm Analysis of Large Fluidized Catalytic Cracking (FCC) Reactors

 DPM Analysis of Large Fluidized Catalytic
Cracking (FCC) Reactors

Abstract:

Computational
Fluid Dynamic (CFD) modeling is a powerful tool for equipment design and
development and is widely used at UOP, particularly for the reactor and
regenerator design of FCC process unit. Through CFD modeling, a technical
solution was developed for a large capacity FCC process unit purposing an
elevated amount of propylene production. 

A key
challenge in FCC process design is how to optimize the size of the reactor
vessel, which is a function of the number and size of reactor cyclones
(catalyst separation disengagers).  UOP developed a new cyclone cluster
configuration via CFD study of the reactor internals, including UOP’s VSS™
riser termination device and reactor cyclones, which reduce the reactor size
significantly compare to the conventional design, while maintaining effective
catalyst / vapor separation and mechanical reliability.  The objective of the current CFD study is to
evaluate the catalyst separation efficiency and performance of the new riser
termination device technology, which accommodate more cyclones in a smaller
reactor vessel.

To better
understand the flow pattern, flow distribution and the gas residence time inside
the UOP VSS^TM , the analysis was broken
down into two sections. Part 1 focused on single gas phase only and in part 2 the
particles behavior is studied using the Discrete Phase Model (DPM) in Fluent.

The single
gas flow analysis results showed that the flow in the VSS chamber section has the
same rotational pattern as in conventional FCC/VSS units, where the catalyst
will separate from the gas products. Also the gas flow distribution at each
chamber arm is uniform, which is critical to catalyst separation efficiency.

The DPM
analysis confirmed an equal catalyst particle distribution through all the
cyclones and a high efficiency separation in the riser termination device. Having
this information from CFD allows for the new design to move forward.