Fluidizing Low Fines Catalyst Particles Using Obstructing Members
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Solution Overview
Problem
Fluidized bed reactors in oxygenate to olefin (OTO) systems face challenges in maintaining efficient fluidization characteristics due to the loss of catalyst fines, leading to poor circulation and gas distribution, and existing solutions either remove desirable catalyst particles or require the addition of new fines to address this issue.
Innovation Solution
The implementation of obstructing members, such as baffles, within the fluidized bed reactor to facilitate the fluidization of catalyst particles with a low fines content, reducing entrainment and maintaining desirable fluidization characteristics without the need for additional fines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional regeneration vessels are used to fluidize catalyst particles, then coke removal is effective, but significant amount of catalyst fines are entrained and lost through the exhaust outlet
Solution Approach 1:
The fluidized bed is divided into multiple zones using obstructing members (baffles) that segment the continuous flow into distinct regions. This segmentation allows different parts of the bed to perform different functions - upper zones for coke removal and lower zones for catalyst retention, thereby reducing fines loss while maintaining regeneration efficiency
Solution Approach 2:
Obstructing members act as intermediary structures between the gas flow and catalyst particles. These members mediate the interaction by providing physical barriers that trap fines while allowing gas to pass through, effectively separating the functions of coke removal and catalyst retention
2Ease of operation
If catalyst fines are removed from the system to improve fluidization characteristics, then circulation and gas distribution improve, but desirable catalyst particles are also removed
Solution Approach 1:
Different regions of the fluidized bed are given different qualities through obstructing members. The lower regions have structures that promote fine particle suspension for good fluidization, while upper regions have structures that promote catalyst retention. This local differentiation allows simultaneous optimization of fluidization characteristics and catalyst retention
Solution Approach 2:
The system dynamically adjusts the behavior of catalyst particles through obstructing members that respond to fluid flow patterns. The members create varying flow regimes that adapt to the catalyst population composition, allowing the system to maintain good fluidization while retaining fines through continuous adjustment of particle trajectories
3Reliability
If large catalyst particles are selectively retained in OTO reaction systems, then catalyst stability is improved, but fluidization performance deteriorates due to poor circulation and gas distribution
Solution Approach 1:
The problem is solved by adding a spatial dimension to particle retention through obstructing members positioned at different heights and locations. Instead of relying solely on particle size separation in one dimension, the system uses three-dimensional arrangement of baffles to create multiple retention zones, thereby maintaining stability while improving fluidization performance through enhanced circulation paths
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 approach effectively minimizes catalyst loss and maintains good fluidization characteristics in reactors with low fines content, improving the operational efficiency of OTO systems by enhancing the circulation and distribution of catalyst particles.
Implementation Method 1
contacting the catalyst particles with a fluidizing medium under conditions effective to cause the catalyst particles to behave in a fluidized manner and form a fluidized bed
Implementation Method 2
contacting the particles with one or more primary obstructing members while in the fluidized bed
Data Source
AI summary
The present invention relates to processes for fluidizing a population of catalyst particles that are depleted of catalyst fines. In one embodiment, the process includes providing a plurality of catalyst particles in the reactor, wherein the catalyst particles have a d2 value of greater than about 40 microns. The catalyst- particles are contacted with a fluidizing medium under conditions effective to cause the catalyst particles to behave in a fluidized manner and form a fluidized bed. The particles are contacted with one or more primary obstructing members while in the fluidized bed. By fluidizing the catalyst particles in this manner, the catalyst particles can be maintained at an axial gas Peclet number of from about 10 to about 20.