Upflow Regenerator for FCC Catalyst with Variable Diameter Zones
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Solution Overview
Problem
Existing regeneration methods for spent Fluid Catalytic Cracking (FCC) catalysts from multiple reactors result in excessive hydrothermal and metal deactivation due to varying coke content, as catalysts with different coke levels are exposed to uniform regenerator conditions, leading to accelerated deactivation.
Innovation Solution
An upflow regenerator with multiple diameter zones is used, where spent catalysts with higher coke content are fed at the bottom and those with lower coke content are fed at higher elevations, adjusting residence time to minimize exposure to regenerator conditions, thereby reducing hydrothermal and metal deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If spent catalysts from multiple reactors with varying coke content are regenerated in a single regenerator, then the regenerator structure is simple, but hydrothermal and metal deactivation of catalyst is accelerated
Solution Approach 1:
The regenerator is divided into multiple diameter zones along the vertical flow path, with each zone having a different cross-sectional area. This segmentation allows different spent catalyst streams with varying coke contents to be introduced at different elevations and experience different residence times, thereby reducing hydrothermal and metal deactivation while maintaining a single regenerator structure.
Solution Approach 2:
Different zones of the regenerator are designed with different diameters to create varying flow velocities and residence times locally. The regenerator has a smaller diameter at the bottom where high coke content catalyst is introduced, and progressively larger diameter zones upward, creating localized conditions optimized for different coke burning rates and minimizing excessive deactivation.
2Ease of operation
If uniform regenerator conditions are applied to all spent catalysts, then the regenerator operation is simple, but catalyst exposure to regenerator conditions is excessive
Solution Approach 1:
The regenerator employs a dynamic diameter variation along the vertical flow path, creating dynamically varying residence times for different catalyst streams based on their introduction elevation. This dynamic design allows simpler operation compared to multiple regenerators while reducing excessive catalyst exposure time through optimized flow paths.
Solution Approach 2:
The invention adds a vertical dimension to the regenerator design by introducing catalyst at different elevations along the flow path. This dimensional approach allows control over residence time through elevation selection, providing a simpler operational alternative to multiple regenerators while reducing excessive catalyst exposure.
3Reliability
If multiple regenerators are used for spent catalysts with different coke content, then hydrothermal and metal deactivation is reduced, but device complexity and operational cost increase
Solution Approach 1:
Multiple spent catalyst streams with different coke contents are merged into a single regenerator system, which processes all streams simultaneously through strategically designed injection points and diameter zones. This merging approach reduces device complexity and operational costs compared to multiple separate regenerators while maintaining reduced hydrothermal and metal deactivation through optimized residence time control.
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 effectively reduces hydrothermal and metal deactivation of the catalyst by optimizing residence time and exposure to regenerator conditions, achieving targeted coke burning levels without the need for multiple regenerators, thus enhancing catalyst lifespan and operational efficiency.
Implementation Method 1
The coke is removed by burning it with air in the regenerator and thereby restoring its catalytic activity
Implementation Method 2
A fluid catalytic cracking process employs fine catalyst particles acting like fluid when fluidized with the hydrocarbon vapors in a reactor
Data Source
Figure 1
AI summary
This invention relates to a process and an apparatus for regeneration of spent FCC catalyst using multiple reactors operation resulting in wide variation of coke on spent catalyst are disclosed. This process uses an up flow regenerator with divided injection of spent catalyst based on their coke content to control the residence time for its efficient regeneration and reduced hydrothermal deactivation. This system has the advantage of minimizing the exposure to the high temperature of low coked catalyst to the minimum possible time and high coke contained catalyst to the required time for its complete regeneration.