MTO Regenerator Multi-Pass Grids for Uniform Catalyst Flow
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Solution Overview
Problem
Deep catalyst beds in methanol to olefins (MTO) regenerators experience uneven gas flow distribution, leading to segregated regions and reduced carbon burning rates due to coalescing gas bubbles, resulting in uneven catalyst regeneration.
Innovation Solution
The regenerator design incorporates multi-pass grids oriented horizontally across the vessel's cross-section with small openings for gas flow and larger offset openings for catalyst passage, preventing gas bubble coalescence and ensuring uniform catalyst distribution and residence time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a deep catalyst bed is used in the regenerator, then sufficient residence time is achieved for coke combustion, but gas flow distribution becomes uneven and gas bubbles coalesce, leading to segregated regions
Solution Approach 1:
The regenerator is divided into multiple stages with horizontal grids at different heights, creating separate combustion zones. Each grid segment distributes gas flow independently, preventing bubble coalescence and maintaining uniform gas-catalyst contact throughout the deep bed, thereby achieving both sufficient residence time and uniform gas flow distribution
Solution Approach 2:
Horizontal grids with distributed openings act as intermediary structures between the gas inlet and catalyst bed. These grids break up large gas bubbles into smaller streams and redistribute gas uniformly across the catalyst bed cross-section, preventing segregation while maintaining adequate residence time for combustion
2Productivity
If gas bubbles coalesce in deep catalyst beds, then gas flow paths become segregated, but this reduces carbon burning rates and regeneration uniformity
Solution Approach 1:
The combustion process is segmented into multiple zones by horizontal grids, with each zone providing uniform gas distribution. This segmentation prevents bubble coalescence that would otherwise create segregated regions, ensuring consistent carbon burning rates and uniform regeneration across the entire catalyst bed
Solution Approach 2:
The grid openings are designed with specific size parameters (smaller than catalyst particles but large enough for gas flow) to change the gas flow regime from bubbly flow to more uniform distributed flow. This parameter change prevents bubble coalescence and maintains both high carbon burning rates and uniform regeneration
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 design enhances gas-catalyst mixing, reduces segregation, and achieves more uniform catalyst regeneration, allowing for a smaller regenerator vessel and lower catalyst inventory, thereby reducing costs and improving the MTO process efficiency.
Implementation Method 1
Each grid comprises a plurality of small openings of sufficient size to allow gas to flow through the grids, but with the openings sufficiently small to prevent the flow of catalyst particles
Implementation Method 2
The regeneration process includes burning, or combusting, carbon deposits on the catalyst, or coke. The coke is combusted with a hot, but oxygen lean gas to regenerate the catalyst
Implementation Method 3
The catalyst typically flows down through a regenerator as a fluidized bed, with the regeneration gas, or combustion gas, flowing upward through the catalyst bed
Data Source
AI summary
A process and device for the regeneration of catalyst is presented. The device includes a series of grids within a regeneration vessel, where each grid includes small openings for the passage of gas, and larger openings for the passage of catalyst. The grids span horizontally across the vessel, and are spaced vertically apart to create a flow of catalyst down through the regenerator.