Fluidizing Catalyst Bed Top Down to Protect Internals
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Solution Overview
Problem
The re-fluidization of a catalyst bed in a catalyst cooler can cause the entire mass of catalyst to thrust against the internals, potentially damaging them, due to sudden fluidization, which is costly and should be minimized for optimal operation.
Innovation Solution
Gradually fluidizing the catalyst bed from the top down by initiating fluidization in upper and intermediate sections before the lower section, using distributed gas from upper and lower fluidization distributors to avoid sudden thrust and protect internal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the catalyst bed is fluidized suddenly from the bottom, then the fluidization process can be initiated quickly, but the entire mass of catalyst thrusts against the internals causing damage
Solution Approach 1:
The fluidization process is segmented into multiple stages with different gas flow rates. The method divides the catalyst bed into upper and lower sections, applying different fluidization conditions to each section sequentially. This segmentation allows controlled initiation that prevents sudden thrust against internals while still achieving quick fluidization.
Solution Approach 2:
Before full fluidization is initiated, a preliminary action is performed by first fluidizing only the upper section of the catalyst bed at a higher gas flow rate. This preliminary step prepares the system by lifting the upper catalyst mass first, preventing it from thrusting against internals when full fluidization begins.
2Productivity
If the gas flow rate is increased rapidly to fluidize the catalyst bed, then productivity is improved, but damage to internals occurs due to catalyst thrust
Solution Approach 1:
The gas flow rate is segmented into different levels applied to different sections. The upper section receives a higher gas flow rate initially, while the lower section receives a lower flow rate. This segmented approach maintains high productivity by quickly fluidizing the upper section while protecting internals from damage by limiting the flow rate in the lower section where catalyst thrust occurs.
Solution Approach 2:
Different gas flow rates (different qualities) are applied locally to different sections of the catalyst bed. The upper section receives high gas flow for rapid fluidization, while the lower section receives controlled gas flow to prevent catalyst thrust. This local differentiation resolves the contradiction between productivity and damage prevention.
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 method prevents damage to the catalyst cooler internals by gradually fluidizing the catalyst bed, ensuring continuous operation and minimizing downtime and maintenance costs.
Implementation Method 1
fluidizing the bed of catalyst from the top down... distributing gas below an upper section of the bed of catalyst to fluidize the upper section... distributing gas below a lower section of the bed of catalyst to fluidize the lower section
Data Source
AI summary
A process and apparatus is disclosed for gradually starting fluidization in a bed of particulate from the top down so as to avoid thrusting the entire mass of particulates upwardly in the bed at the same time which may damage internals in the bed. The particulate bed may comprise a catalyst cooler for an FCC unit containing internals such as cooling, fluidization and support equipment.