FCC Riser Disengagement Tunnel and Baffle for Erosion Control
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Solution Overview
Problem
In the Fluid Catalytic Cracking (FCC) process, the swirling motion of catalyst particles and gaseous products causes erosion of internal equipment and flow maldistribution, leading to reduced product yield due to prolonged residence time of product gases with catalyst, which continues cracking reactions.
Innovation Solution
Implementing a tunnel with a vertical wall to dampen the rotational flow of catalyst particles and gaseous products, requiring them to change direction before entering the reactor annulus, and using a baffle to deflect and pre-strip catalyst particles laterally, reducing their entry into the reactor annulus and minimizing erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a disengaging chamber is used to separate catalyst particles from gaseous products, then separation efficiency is improved, but swirling motion causes erosion of internal equipment and flow maldistribution
Solution Approach 1:
A baffle is introduced as an intermediary element between the swirling catalyst-gas mixture and the reactor annulus. The baffle deflects the swirling flow, preventing direct contact between the catalyst particles and the reactor annulus walls, thereby reducing erosion while maintaining separation efficiency.
Solution Approach 2:
The harmful swirling motion is extracted and redirected away from the reactor annulus. By using the baffle to deflect the flow laterally, the patent removes the erosive effect from the system while preserving the beneficial separation function of the disengaging chamber.
2Productivity
If catalyst particles are allowed to swirl and exit the disengaging chamber, then flow continuity is maintained, but residence time of product gases is prolonged causing continued cracking reactions
Solution Approach 1:
The baffle creates a shortcut path that allows the catalyst-gas mixture to quickly transition from the disengaging chamber to the reactor annulus without prolonged residence. The lateral deflection enables the flow to 'skip' over the erosive zone, reducing residence time and preventing continued cracking reactions while maintaining flow continuity.
3Object-affected harmful factors
If the disengaging chamber is designed to prevent catalyst entry into reactor annulus, then erosion is reduced, but separation efficiency may be compromised
Solution Approach 1:
The baffle is strategically positioned to provide protection only in the specific zone where erosion occurs (at the reactor annulus interface). The rest of the disengaging chamber maintains its separation function without interference, achieving local erosion protection while preserving overall separation efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces hardware erosion, prevents catalyst short-circuiting, and decreases the residence time of product gases, thereby enhancing gasoline yield and selectivity while protecting stripping internals from abrasion.
Implementation Method 1
The vertical wall presents a face that is opposed to the angular direction in which the catalyst particles and gaseous products swirl. Consequently, the angular momentum of the catalyst particles and gaseous products is reduced.
Implementation Method 2
A baffle may be located at the intersection between a reactor annulus and a disengaging chamber to deflect catalyst laterally in a stripping section after descending below a passage to the reactor annulus.
Data Source
AI summary
In an FCC apparatus in which swirl arms are used to discharge gas and catalyst from a riser, the swirling movement of the catalyst particles is inhibited while impeding the catalyst particles and gaseous products from exiting the disengaging chamber and entering a reactor annulus. The catalyst particles and gaseous products pass through a tunnel comprising a vertical wall to enter the reactor annulus. The vertical wall presents a face that is opposed to the angular direction in which the catalyst particles and gaseous products swirl.A baffle may be located at the intersection between the reactor annulus and the disengaging chamber to deflect catalyst laterally in a stripping section after exiting the reactor annulus. The baffle may be equipped with openings to fluidize the large proportion of catalyst passing over this region to effectively pre-strip this catalyst before it enters a stripping section.