Swirl Impeding Plates in FCC Gas Recovery Conduits
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Solution Overview
Problem
In the FCC process, the swirling motion of gases and catalysts entering the gas recovery conduit continues into the cyclones, causing erosion and reducing separation efficiency due to the tangential discharge from the riser swirl arms, which can be counter to the cyclone swirl motion.
Innovation Solution
Installation of one or more plates in the gas recovery conduit to impede the swirling motion, ensuring that the gas and catalyst mixture enters cyclones without significant swirling, thereby reducing erosion and maintaining separation efficiency regardless of the orientation between the riser swirl arms and cyclones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tangential discharge from riser swirl arms is used to separate catalyst from gas, then initial separation efficiency is improved, but erosion of downstream equipment increases
Solution Approach 1:
The invention converts the harmful swirling motion that causes erosion into a beneficial force by directing it against the cyclone inlet. The swirl arms create rotational flow that would normally erode downstream equipment, but this same swirl is channeled to enhance the cyclone separation process, improving catalyst-gas separation while protecting equipment from erosion
Solution Approach 2:
The gas recovery conduit acts as an intermediary element that transforms and directs the swirling flow from the riser swirl arms into the cyclone. This intermediate structure modifies the flow characteristics, converting the harmful direct swirl into a controlled rotational pattern that benefits cyclone operation without causing erosion to intermediate equipment
2Productivity
If counter-oriented swirl arms are used, then separation efficiency may improve, but equipment complexity and sensitivity to orientation increases
Solution Approach 1:
The riser swirl arms are designed to perform multiple functions: they create the necessary swirl for separation, protect downstream equipment from erosion, and their orientation becomes less critical due to the cyclone's inherent ability to handle various flow patterns. This multi-functionality reduces sensitivity to precise orientation while maintaining separation efficiency
Solution Approach 2:
The invention changes the operational parameters of the system by allowing a range of orientations for the swirl arms rather than requiring a specific counter-oriented configuration. This parameter change makes the system more flexible and less sensitive to orientation while maintaining effective separation through the cyclone's design
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
The swirl impeding device effectively mitigates erosion and maintains separation efficiency by ensuring a straight flow into cyclones, enhancing the durability of equipment and the separation process.
Implementation Method 1
Installation of one or more plates in the gas recovery conduit to impede the swirling motion, ensuring that the gas and catalyst mixture enters cyclones without significant swirling
Implementation Method 2
The most common method of separating particulate solids from a gas stream uses centripetal separation. Centripetal separators are well known and operate by imparting a tangential velocity to gases containing entrained solid particles that forces the heavier solids particles outwardly away from the lighter gases
Implementation Method 3
The centripetal acceleration associated with an exterior of the vortex causes catalyst particles to migrate towards the outside of the barrel while the gaseous materials enter an interior of the vortex
Data Source
AI summary
A process is disclosed for the separation of solids from gases in a mixture which is most particularly applicable to an FCC apparatus. The mixture of solids and gases are passed through a conduit and exit through a swirl arm that imparts a swirl motion having a first annular direction to centripetally separate the heavier solids from the lighter gases. The mixture then enters a gas recovery conduit in which at least one plate radially extending from an inner wall impedes rotational motion of the mixture. The mixture enters cyclones at the other end of the gas recovery conduit without substantial swirling motion.