Collector Assembly with Variable Porosity Zones for Radial Reactors
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Solution Overview
Problem
Radial bed reactors face limitations due to catalyst pinning and pressure drop disparities, leading to reduced feed flow rates and catalyst deactivation, as high feed flow rates cause catalyst immobilization and preferential pathways in the catalytic bed.
Innovation Solution
A collector assembly with a vertical cylindrical screen and a concentric cylindrical tube, featuring zones with reduced permeability to control pressure drop and reduce catalyst pinning, allowing for adjustable porosity to balance pressure distribution across the catalytic bed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high feed flow rate is used, then productivity is improved, but catalyst pinning occurs causing catalyst immobilization and deactivation
Solution Approach 1:
The collector tube is equipped with variable porosity zones - high porosity zones in regions prone to pinning to reduce friction and maintain catalyst mobility, and low porosity zones in regions requiring better gas-catalyst contact. This local differentiation resolves the contradiction by allowing high feed flow rates without uniform catalyst immobilization across the entire collector surface.
Solution Approach 2:
The invention changes the porosity parameter of the collector tube zones to control the balance between gas flow and catalyst mobility. By adjusting porosity values in different zones, the system maintains catalyst mobility even at high feed flow rates, preventing deactivation while preserving productivity.
2Productivity
If high feed flow rate is used, then productivity is improved, but pressure drop disparities increase causing preferential pathways
Solution Approach 1:
Variable porosity zones are strategically positioned to balance pressure drop across different regions of the catalytic bed. High porosity zones compensate for regions with naturally lower pressure drop, while low porosity zones prevent excessive pressure drop in well-performing regions. This maintains uniform gas flow distribution and prevents preferential pathways even at high feed flow rates.
3Device complexity
If uniform porosity is used in collector tube, then device complexity is reduced, but catalyst pinning and pressure drop disparities increase
Solution Approach 1:
The collector tube is designed with non-uniform porosity distribution, creating zones with different permeability characteristics. This increases device complexity slightly but dramatically improves catalyst mobility and prevents pinning by providing localized flow control that adapts to different regions of the catalytic bed.
4Device complexity
If uniform porosity is used in collector tube, then device complexity is reduced, but pressure drop disparities increase causing preferential pathways
Solution Approach 1:
Different porosity zones in the collector tube create localized pressure drop characteristics that compensate for regional variations in the catalytic bed. This non-uniform structure increases device complexity but ensures uniform overall pressure drop distribution, preventing gas channeling and preferential pathways.
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 collector assembly effectively reduces catalyst pinning and pressure drop disparities, enhancing the operational stability and efficiency of radial bed reactors by maintaining uniform feed distribution and reducing catalyst deactivation.
Implementation Method 1
the pressure drop is capable of being controlled in a manner such as to limit the disparities and thus reduce the risks of the formation of preferential pathways for the gaseous fluid in the catalytic bed
Implementation Method 2
a vertical cylindrical screen which is permeable to gaseous fluid and impermeable to particles of catalyst
Implementation Method 3
The force exerted by the feed moving radially from the outer periphery of the catalyst bed towards the centre over the grains of catalyst pins them against the wall of the central collector, which increases the frictional load which then opposes sliding of the grains along the wall
Implementation Method 4
Each zone with reduced permeability has a lower porosity than that of a zone which is permeable to gaseous fluid. The porosity of a zone is defined by the ratio between the total permeable surface area of said zone and the total developed surface area of said zone
Data Source
AI summary
The invention concerns a collector assembly (8) for a gaseous fluid suitable for being disposed in a reaction section with a moving bed of catalyst of a radial reactor. The collector assembly comprises a vertical cylindrical screen (9), permeable to gas and impermeable to particles of catalyst, and a vertical cylindrical tube (10) which is supported by this screen (9) and disposed in a concentric manner with respect to the screen. The tube (10) comprises one or more zones (17a, 17b) which are permeable to gaseous fluid, comprising a plurality of through holes and a plurality of zones (18a, 18b, 18c, 18d) with a reduced permeability to gaseous fluid compared with the permeable zone. Each zone with a reduced permeability has a porosity, defined as the ratio between total permeable surface area of the zone and total developed surface area of this zone, in the range 0 to 0.005.