Cyclone Separator Pre-treatment for Catalyst Attrition Reduction
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Solution Overview
Problem
High velocity separation methods in catalyst recovery systems result in significant attrition of alkane or alkyl aromatic dehydrogenation catalyst particles, leading to loss of active components and increased costs due to the high impact velocities of catalyst particles on cyclone walls, especially in propane dehydrogenation (PDH) processes.
Innovation Solution
A pre-treatment step using a combined flow deflector to reduce the gas flow velocity and change the direction of the catalyst and gas stream before high velocity separation, minimizing the percentage of catalyst particles that contact the high velocity separation means, thereby reducing attrition rates by at least 15%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high velocity separation means is used to separate catalyst particles from entraining gas, then separation efficiency is improved (at least 99.8% of catalyst particles removed), but catalyst particle attrition increases due to high impact velocities on cyclone walls
Solution Approach 1:
The separation process is divided into two distinct stages: a first cyclone separator operating at lower gas flow velocity (7.6-15.2 m/s) to remove the majority of catalyst particles, and a second cyclone separator operating at high gas flow velocity (16.8-25.9 m/s) to remove remaining particles. This segmentation allows the system to achieve high overall separation efficiency while minimizing catalyst attrition by limiting the number of particles exposed to high-velocity conditions.
Solution Approach 2:
The first cyclone separator performs preliminary separation at reduced velocity before the gas stream enters the second cyclone separator. By removing over 80% of catalyst particles in advance at lower velocities, the system prepares the gas stream for final separation at high velocity, thereby reducing the cumulative attrition impact on catalyst particles while maintaining effective separation.
2Manufacturing precision
If gas flow velocity is increased to enhance separation performance, then catalyst particle removal efficiency improves, but the impact velocity of particles on cyclone walls increases resulting in higher attrition rates
Solution Approach 1:
The separation function is segmented across two cyclone separators with different operating velocities. The first cyclone operates at lower velocity (7.6-15.2 m/s) to perform bulk separation with minimal impact damage, while the second cyclone operates at high velocity (16.8-25.9 m/s) to achieve precise removal of remaining fine particles. This segmentation resolves the contradiction by distributing the separation task across different velocity regimes.
Solution Approach 2:
The first cyclone separator performs preliminary removal of the majority of catalyst particles at reduced velocity, thereby reducing the particle load before the gas enters the second cyclone. This preliminary action at lower velocity protects particles from repeated high-velocity impact, reducing cumulative attrition while maintaining high overall separation precision.
3Device complexity
If single-stage high velocity separation is used, then equipment complexity is reduced, but catalyst attrition increases due to all particles being exposed to high impact velocities
Solution Approach 1:
The separation system is segmented into two cyclone separators operating at different velocities, connected in series. While this increases equipment count, each cyclone can be designed as a standard unit, and the segmented approach dramatically reduces catalyst loss (by at least 15% according to the patent). The modular nature of cyclone separators makes this segmentation practically implementable without proportionally increasing overall system complexity.
Solution Approach 2:
The system changes the operating parameter (gas flow velocity) between the two cyclone separators. The first cyclone operates at lower velocity (7.6-15.2 m/s) and the second at high velocity (16.8-25.9 m/s). This parameter change allows the system to achieve effective separation while minimizing catalyst attrition, as not all particles are exposed to the highest velocity conditions throughout the entire separation process.
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 pre-treatment process effectively reduces catalyst attrition by removing over 80% of particles before they reach the high velocity separation stage, resulting in a total attrition rate that is at least 15% lower than without the pre-treatment, utilizing a correlation (r = Ku^2 / μ) to calculate the attrition rate.
Implementation Method 1
a directional change away from the combined gas flow, using a combined flow deflector, which directional change is at least 90 degrees from the axis of flow direction
Implementation Method 2
contacting a high velocity separation means at a gas flow velocity of from 16.8 meters per second to 25.9 meters per second and thereby remove from said combined flow at least 99.8 percent of the catalyst particles
Implementation Method 3
the pre-treatment step combination of velocity and direction change causes removal from the combined flow greater than 80 percent of the catalyst particles
Implementation Method 4
a total catalyst attrition rate calculated in accord with the correlation , where r is attrition rate (mass of catalyst attrited per hour per mass of catalyst impacted per hour), K is a catalyst specific attrition rate constant, u is the impact velocity (meters per second), and μ is solids-to-gas loading ratio (mass of catalyst to mass of gas)
Data Source
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AI summary
An improved process and an improved apparatus for minimizing attrition of catalyst particles, especially propane dehydrogenation catalyst particles, entrained in a combined flow of such particles and an entraining gas in a catalyst recovery means during separation of such particles from the entraining gas, by use of a pre-treatment step in which the combined flow is at a rate between 7.6 and 15.2 meters per second are provided.