FCC Stripping Vessel Grid and Packing Design
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Solution Overview
Problem
Existing FCC stripping vessels face inefficiencies due to catalyst accumulation and gas bypassing, leading to reduced stripping efficiency and hydraulic issues, particularly when structured packing occupies less vertical space, causing excessive catalyst levels and channeling.
Innovation Solution
A vessel design incorporating a first section with grids and a second section of structured packing, where the grids occupy empty space above the inlet to distribute catalyst and gas, minimizing accumulation and facilitating efficient stripping by reducing the need for extensive field welding during installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If structured packing is used to reduce vertical space occupation, then space utilization is improved, but catalyst accumulation and gas bypassing occur leading to reduced stripping efficiency
Solution Approach 1:
The stripping vessel is divided into multiple sections: an upper section with distributed catalyst discharge points and a lower section with structured packing. This segmentation allows the upper section to prevent catalyst accumulation while the lower section performs efficient stripping, resolving the contradiction between space utilization and stripping efficiency.
Solution Approach 2:
The distributed catalyst discharge points act as intermediaries between the catalyst inlet and the structured packing. These discharge points regulate catalyst flow and prevent direct accumulation above the packing, thereby maintaining stripping efficiency while allowing compact packing design.
2Ease of operation
If structured packing is installed without obstruction, then installation simplicity is improved, but catalyst level becomes excessive causing compression and gas bypassing
Solution Approach 1:
The structured packing is pre-positioned in the lower section with specific height and configuration designed to control catalyst level. This preliminary arrangement ensures proper catalyst distribution and prevents excessive accumulation, achieving precise level control while maintaining simple installation procedures.
3Quantity of substance
If catalyst inventory is increased to prevent accumulation, then catalyst availability is improved, but gas channeling and hydraulic issues occur
Solution Approach 1:
The catalyst discharge points are distributed horizontally across multiple locations in the upper section rather than concentrated at a single point. This spatial distribution in another dimension prevents vertical accumulation and eliminates gas channeling pathways, allowing adequate catalyst inventory without harmful effects.
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
The vessel design enhances stripping efficiency by preventing catalyst compression and gas bypassing, while reducing installation time and labor costs by minimizing the requirement for field welding, thus improving overall process efficiency and reducing downtime.
Implementation Method 1
Fluidization of the catalyst particles by various gaseous streams allows the transport of catalyst between the reaction zone and regeneration zone
Implementation Method 2
The most common method of stripping hydrocarbons from the catalyst utilizes a stripping gas, usually steam, passed through a stream of catalyst, counter-current to the direction of flow of the catalyst
Data Source
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AI summary
A vessel provides for removing hydrocarbons from a catalyst. In an FCC unit, the vessel includes first and second sections. The first section includes at least one grid having a plurality of intersecting members and openings therebetween. The second section includes structured packing such as a plurality of ribbons. Grids are supported by pipes that are supported by the second section.