Segmented Baffle System for FCC Riser Retrofit
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Solution Overview
Problem
Conventional baffle systems in fluid catalytic cracking (FCC) risers face challenges in retrofitting existing designs without substantial reconstruction and controlling erosion, leading to non-uniform catalyst and vapor velocity profiles, which result in suboptimal cracking efficiency due to back mixing and over/under-conversion of hydrocarbons.
Innovation Solution
A segmented baffle system with interlocking segments and a specific angle configuration (30-50 degrees for the lower surface and 10-50 degrees for the upper surface) is designed to be installed within the riser, featuring a groove and ridge mechanism or pin-based interlocking, allowing for secure positioning without extensive reconstruction and minimizing erosive eddies, thereby promoting a uniform velocity profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional baffle systems are installed in FCC risers, then catalyst and vapor velocity profiles can be improved, but substantial reconstruction and repair of the existing riser is required
Solution Approach 1:
The baffle system is divided into multiple segments that can be independently installed and positioned within the riser. Each segment can be installed separately through the riser inlet, eliminating the need for substantial reconstruction. The segments are designed to assemble together to form the complete baffle structure, enabling retrofits in existing FCC units without taking the entire riser offline for extensive repair work.
2Productivity
If baffles are installed to adjust velocity profile, then uniform flow distribution is achieved, but erosion must be controlled downstream of the baffles
Solution Approach 1:
The downstream surface of each baffle segment is designed with a curved profile rather than a sharp edge. This curvature helps to smooth the flow transition and reduce the intensity of eddies forming downstream of the baffle. By rounding the downstream edge, the design minimizes localized high-velocity regions that would otherwise cause severe erosion on the riser wall and downstream components.
3Productivity
If non-uniform velocity profiles occur in the riser, then back mixing and catalyst slip increase, but the desired plug flow regime is not achieved
Solution Approach 1:
The baffles are positioned at specific locations within the riser where velocity non-uniformities are most pronounced, particularly near the walls. Each baffle is angled to redirect flow locally, creating a more uniform velocity distribution across the riser cross-section. The local flow modification at multiple positions along the riser collectively achieves the desired plug flow regime throughout the entire reactor.
Data Source
AI summary
According to one aspect of the invention, a riser includes a cylindrical housing defined by a sidewall having an interior surface and an exterior surface. A baffle is defined by a first segment and a second segment, wherein the baffle is designed to be positioned on the interior surface of the riser and wherein the first segment and second segment are releasably interlockable.