Moving Bed Granular Filter for FCC Separation
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Solution Overview
Problem
Current gas-solid separation devices in fluid catalytic cracking units face inefficiencies due to high pressure drops, equipment wear, and dust particle recirculation, particularly in large FCC units, where multi-tubular cyclones require high manufacturing accuracy and result in complex layouts and increased costs.
Innovation Solution
A separation device integrating a large diameter individual cyclone separator with a moving granular bed, utilizing a tangential flow reversal structure and a Johnson screen cross-flow area, coupled with a granule recycle and regeneration unit to achieve synergistic centrifugal separation and filtration, reducing pressure drop and enhancing separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-tubular cyclone separators with small diameter tubes are used to achieve high separation efficiency, then dust concentration is reduced below 200 mg/m³, but the number of tubes increases leading to complex layout, increased floor area, and higher material costs
Solution Approach 1:
The invention divides the cyclone separation system into multiple functional stages: a first-stage cyclone separator for coarse particle removal, a second-stage cyclone separator for fine particle removal, and a moving bed granular filter for ultra-fine particle removal. This segmentation allows each stage to be optimized for its specific separation task, achieving high overall separation efficiency without requiring a large number of small-diameter tubes in parallel
Solution Approach 2:
The moving bed granular filter serves as an intermediary component between the two cyclone separators. It receives particles from the first-stage cyclone, performs intermediate separation, and feeds purified gas to the second-stage cyclone. This intermediary filtering stage reduces the burden on both cyclone separators, allowing them to operate at optimal conditions with fewer tubes
2Productivity
If the number of cyclone tubes is increased to ensure handling capacity, then gas-solid separation efficiency is maintained, but floor area and material costs increase
Solution Approach 1:
The moving bed granular filter is nested within the vertical space of the cyclone separator system. The filter bed is positioned in the lower section of the cyclone housing, utilizing the vertical dimension rather than requiring additional horizontal floor area. This nested arrangement allows the filtering function to be integrated into the existing cyclone structure
Solution Approach 2:
The invention transitions from a horizontal arrangement of multiple parallel cyclone tubes (occupying floor area) to a vertical arrangement with stacked cyclone stages and a nested moving bed filter (utilizing vertical space). This dimensional change allows the system to achieve the same handling capacity with significantly reduced floor footprint
3Manufacturing precision
If inlet gas velocity of single tube is increased to maintain separation efficiency, then dust concentration is reduced, but equipment wear and catalyst particle smashing are aggravated
Solution Approach 1:
Instead of using a single cyclone separator operating at excessively high inlet velocity, the invention distributes the separation task across multiple stages with moderate velocities. The first-stage cyclone operates at lower velocity for coarse separation, the moving bed filter provides intermediate filtration, and the second-stage cyclone performs fine separation. This partial action approach achieves the same overall separation efficiency without the harmful effects of excessive velocity in any single component
4Reliability
If a third-stage cyclone is added to reduce dust concentration for flue gas turbine operation, then energy recovery stability is improved, but pressure drop and energy consumption increase
Solution Approach 1:
The invention changes the separation mechanism parameter from pure cyclonic separation to a combination of cyclonic separation and moving bed granular filtration. The moving bed filter operates at lower pressure drop compared to a third-stage cyclone, while achieving similar or better dust removal efficiency. This parameter change in the separation mechanism reduces the overall pressure drop of the system
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 solution effectively lowers the pressure drop to 5-10 kPa, reduces dust concentration to 50 mg/m3, and ensures sustainable recycling of granules, improving energy efficiency and environmental protection while simplifying the system's layout and maintenance.
Implementation Method 1
a separation unit disposed inside the third-stage cyclone housing comprises: a cyclone separator and a moving bed coupled to each other
Implementation Method 2
A separation device integrating a large diameter individual cyclone separator with a moving granular bed, utilizing a tangential flow reversal structure and a Johnson screen cross-flow area
Data Source
AI summary
A separation device, comprising: a third-stage cyclone housing, a separating unit, and a granule recycle and regeneration unit, wherein, the separating unit is disposed inside the third-stage cyclone housing and comprises: a cyclone separator and a moving bed coupled to each other; the granule recycle and regeneration unit comprises: a riser, a spouted bed regenerator, and a regeneration pipe connecting the spouted bed regenerator with the moving bed; the spouted bed regenerator has upper and lower ends opposing to each other, wherein, the upper end of the spouted bed regenerator is provided with a sleeve which opens downwardly, the sleeve divides an interior of the spouted bed regenerator into a fountain area and an annular gap area, and a regenerating gas outlet which is in communication with the annular gap area is provided on a side wall of the spouted bed regenerator. A centrifugal separation and intercepting filtration of the moving granular bed to fine particles can separate fine particles under low pressure drop, and can continuously separate the captured dust particles and the moving bed granules ensuring a sustainable recycling of the moving bed granules.