Catalyst Mixing Riser with Asymmetric Inlet Angles
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Solution Overview
Problem
The existing processes for mixing carbonized and regenerated catalysts in fluid catalytic cracking (FCC) units face challenges in achieving thorough mixing, leading to non-selective cracking and undesirable product compositions due to temperature variations and inefficient mixing geometries, which increase capital costs and require larger process units.
Innovation Solution
The proposed solution involves feeding a first catalyst stream downwardly and a second catalyst stream horizontally into a riser, with specific angular intersections and trajectories to facilitate thorough mixing, utilizing a unique geometry that includes a mixing insert and varying angles of entry to ensure comprehensive mixing and reduce the height requirements of the mixing chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large mixing chamber is designed to process large amounts of feed, then the processing capacity is improved, but the capital cost and catalyst inventory requirements increase
Solution Approach 1:
The patent changes the geometric configuration of the mixing chamber from a conventional large-volume design to a compact configuration with specific angular inlet arrangements. By optimizing the spatial arrangement of catalyst streams entering the riser at different angles, the mixing chamber achieves effective mixing with reduced volume, thereby lowering capital cost while maintaining processing capacity.
Solution Approach 2:
The patent modifies the geometric parameters of the mixing chamber, specifically the angles at which catalyst streams intersect the riser and the trajectory of the streams. By changing these parameters to create optimal mixing conditions within a smaller volume, the system achieves high processing capacity without requiring proportionally large capital investment.
2Volume of stationary object
If conventional mixing geometries are used, then the mixing chamber volume is reduced, but thorough mixing is not achieved leading to non-selective cracking
Solution Approach 1:
The patent employs asymmetric inlet geometries where catalyst streams enter the riser at different angles rather than symmetric arrangements. The first catalyst stream intersects the riser at a first angle while the second stream intersects at a second angle, creating asymmetric flow patterns that enhance mixing efficiency. This asymmetric design achieves thorough mixing within a compact volume, preventing non-selective cracking.
Solution Approach 2:
The patent incorporates preliminary mixing actions by arranging the catalyst streams to mix before entering the main reaction zone. The angular intersections and trajectories are designed to create mixing conditions in advance, ensuring uniform catalyst temperature and composition are achieved prior to hydrocarbon contact, thereby preventing non-selective cracking.
3Device complexity
If catalyst streams enter the riser at the same angles, then the geometry is simplified, but mixing efficiency is reduced
Solution Approach 1:
The patent deliberately introduces asymmetry in the conduit geometries by setting different intersection angles for the first and second catalyst streams. The first stream intersects the riser at a first angle while the second stream intersects at a second angle, creating complementary flow patterns that enhance mixing. This asymmetric design, while slightly more complex, significantly improves mixing efficiency and catalyst temperature uniformity.
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 enhances the uniformity of catalyst temperatures, improves mixing efficiency, and reduces the overall height of the mixing chamber, resulting in more uniform catalyst contact with hydrocarbon feeds and improved product selectivity, thereby increasing the value of hydrocarbon products.
Implementation Method 1
The first stream of catalyst and the second stream of catalyst are passed up the riser
Implementation Method 2
feeding a first catalyst stream downwardly to the riser while feeding a second catalyst stream horizontally to the riser fosters thorough mixing
Data Source
AI summary
A process and apparatus for mixing streams of regenerated and carbonized catalyst utilizes a ramp or bend provided on only one of the catalyst conduits to provide mixing advantages.