Catalyst Mixing Baffles in FCC Riser for Temperature Equilibration
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Solution Overview
Problem
The existing processes for mixing carbonized and regenerated catalysts in fluid catalytic cracking (FCC) require large mixing chambers, increasing capital costs and catalyst inventory, and often result in non-selective cracking due to temperature variations in the catalysts when contacting hydrocarbon feeds.
Innovation Solution
The process involves mixing carbonized and regenerated catalysts at the base of a reactor riser using baffles below the feed distributor, ensuring temperature equilibration before the catalysts contact the hydrocarbon feed, eliminating the need for a separate mixing chamber and improving catalyst uniformity by directing the catalyst streams to opposite sides of the riser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a large mixing chamber is used to mix carbonized and regenerated catalyst, then temperature equilibration is achieved, but capital cost and catalyst inventory increase
Solution Approach 1:
The patent combines the mixing function with the existing reactor riser structure by introducing a U-shaped conduit that allows catalyst to circulate within the riser. This eliminates the need for a separate mixing chamber, achieving temperature equilibration while avoiding additional capital costs and catalyst inventory requirements.
Solution Approach 2:
The reactor riser is given multiple functions: it serves both as the reaction zone and as the mixing chamber for temperature equilibration of carbonized and regenerated catalyst. The U-shaped conduit enables the riser to perform the mixing function without requiring a dedicated separate structure.
2Stability of the object's composition
If carbonized and regenerated catalyst are mixed in a separate chamber, then temperature uniformity is improved, but device complexity increases
Solution Approach 1:
The mixing function is merged with the reactor riser operation. The U-shaped conduit is integrated into the existing riser structure, allowing catalyst circulation and mixing to occur within the same vertical space used for the reaction process, thereby avoiding additional mixing equipment.
Solution Approach 2:
The system uses the existing fluidization and circulation mechanisms of the reactor riser to achieve mixing and temperature equilibration. The catalyst naturally circulates through the U-shaped conduit driven by the fluidization process, eliminating the need for external mixing devices or additional energy input.
3Productivity
If catalyst streams are directed to opposite sides of the riser, then mixing efficiency is improved, but non-selective cracking is reduced
Solution Approach 1:
The catalyst streams are spatially segmented by directing carbonized and regenerated catalyst to opposite sides of the riser through the U-shaped conduit. This segmentation allows for controlled mixing as the catalyst circulates, improving mixing efficiency while preventing localized hot spots that cause non-selective cracking.
Solution Approach 2:
Different regions of the riser are given different functions: one side receives hot regenerated catalyst while the other receives cooler carbonized catalyst. The U-shaped conduit creates localized circulation patterns that promote heat exchange and temperature uniformity in specific zones, preventing non-selective cracking while maintaining overall mixing 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 achieves substantial temperature equilibration and uniform catalyst composition, reducing non-selective cracking and capital costs by integrating the mixing process within the reactor riser, leading to more desirable hydrocarbon product yields.
Implementation Method 1
mixing carbonized and regenerated catalyst at the base of a reactor riser using baffles below the feed distributor, ensuring temperature equilibration before the catalysts contact the hydrocarbon feed
Implementation Method 2
temperature equilibration before the catalysts contact the hydrocarbon feed
Data Source
AI summary
A process for mixing regenerated and carbonized catalyst involves obstructing upward flow of catalyst by one or more baffles between a catalyst inlet and a feed distributor. Each catalyst stream may be passed to opposite sides of a riser. Baffles obstruct upward flow to effect mixing of regenerated and carbonized catalyst to obtain a more uniform temperature and catalyst mixture before contacting the feed.