Two-Stage Regenerator Swirl Duct Catalyst Separation
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Solution Overview
Problem
Conventional regenerators in fluidized catalytic cracking units face inefficiencies in coke combustion, particularly in vessels with shorter elevations, which affects the regeneration of catalysts.
Innovation Solution
A two-stage regenerator process where spent catalyst is partially regenerated in a lower chamber and then transported through a conduit to an upper chamber via flue gas, where it undergoes further regeneration using a swirl duct for separation and additional oxygen contact to achieve complete regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-chamber regenerator is used, then the device complexity is reduced, but the coke combustion efficiency deteriorates
Solution Approach 1:
The regenerator is divided into two separate chambers: a lower chamber for partial burn conditions and an upper chamber for complete combustion. This segmentation allows each chamber to be optimized for its specific function, improving overall coke combustion efficiency while maintaining manageable device complexity through modular design.
2Length of stationary object
If the regenerator vessel elevation is reduced, then the device footprint is minimized, but the catalyst regeneration quality deteriorates
Solution Approach 1:
The regenerator transitions from a vertical single-stage design to a horizontal two-stage configuration. By arranging the partial burn and complete combustion chambers side-by-side rather than stacked vertically, the design achieves thorough regeneration quality while reducing the vessel's elevation requirement.
3Productivity
If two-stage bubbling bed is used, then the coke combustion efficiency is improved, but the device complexity increases
Solution Approach 1:
Each chamber is designed with specific local characteristics optimized for its function: the lower chamber operates under partial burn conditions with specific airflow and catalyst circulation patterns, while the upper chamber is designed for complete combustion. This localized optimization improves coke combustion efficiency without requiring complex integrated systems.
4Speed
If high velocity transport is used, then the catalyst transport speed is increased, but the catalyst entrainment in flue gas increases
Solution Approach 1:
A third chamber serves as an intermediary between the two regenerator chambers and the cyclone separator. This intermediate chamber allows for velocity reduction and proper settling of catalyst particles before they enter the separation system, reducing catalyst entrainment in flue gas while maintaining efficient transport speeds through the regenerator chambers.
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 process enhances the combustion efficiency of coke, ensuring minimal residual coke in the catalyst, thereby improving the overall regeneration process and maintaining partial burn conditions in both chambers.
Implementation Method 1
Fluidization of the catalyst particles by various gaseous streams allows the transport of catalyst between the reaction zone and the regeneration zone
Implementation Method 2
A container may prevent catalyst from exiting the upper chamber through a regenerated catalyst exit without further contact with oxygen gas
Implementation Method 3
A first combustion zone burns a portion of the coke from the catalyst to a first extent to form a first bed of partially regenerated catalyst
Implementation Method 4
maintaining partial burn conditions in both chambers
Data Source
AI summary
A process and apparatus for combusting coke from catalyst two stages is disclosed. Catalyst and flue gas from a lower chamber ascends to an upper chamber to be roughly separated by swirl ducts extending from a combustion conduit. The swirl ducts may discharge into a container in the upper chamber.