Cyclonic Reactor Plenum Design for Low Residence Time
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Solution Overview
Problem
Fluidized reactor systems face challenges in minimizing gas residence time, which affects reaction yield due to long residence times exceeding 1 second, leading to selectivity penalties in processes like propane dehydrogenation, while maintaining mechanical and thermal stability at high temperatures.
Innovation Solution
A cyclonic reactor vessel design featuring a low residence time plenum with a secondary cyclone support system, where secondary cyclones are connected to a first plenum via hanger straps and a second plenum with a smaller volume, minimizing thermal stresses and reducing gas residence time to less than 0.4 seconds through a fluid connection that decouples mechanical attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a conventional plenum design is used to support cyclone stages, then mechanical stability is maintained, but gas residence time increases beyond acceptable limits
Solution Approach 1:
The plenum is divided into a first plenum and a second plenum, with the second plenum having a smaller volume than the first plenum. This segmentation allows the gas residence time to be reduced to less than 0.4 seconds while maintaining the structural support function through the first plenum's connection to the vessel wall.
Solution Approach 2:
The support function is extracted from the second plenum and assigned to the first plenum and vessel wall structure. The second plenum is designed solely for gas collection with minimal volume, removing the contradiction between support stability and residence time by separating these functions into different components.
2Strength
If the plenum is rigidly attached to cyclone stages, then mechanical support is provided, but thermal stress increases due to expansion constraints
Solution Approach 1:
The connection between the second plenum and cyclone outlets is designed to be flexible rather than rigid, allowing thermal expansion and contraction without generating excessive stress. This dynamic connection maintains mechanical support while accommodating thermal movement.
Solution Approach 2:
The plenum connections utilize flexible coupling mechanisms that can accommodate thermal expansion differences between components. The flexible connection allows relative movement between the plenum and cyclone stages, reducing thermal stress while maintaining structural integrity.
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 design effectively reduces gas residence time, minimizing selectivity penalties by maintaining mechanical and thermal stability, achieving a propylene selectivity penalty of less than 0.4 mol% in propane dehydrogenation processes.
Implementation Method 1
minimizing thermal stresses and reducing gas residence time
Implementation Method 2
cyclonic reactor vessel having a low residence time plenum... primary cyclonic separation device... plurality of secondary cyclones
Data Source
Figure 1
Figure 2
AI summary
A cyclonic reactor vessel comprising: a primary cyclonic separation device disposed within the shell and having an outlet; a plurality of secondary cyclones, said secondary cyclones being disposed within the shell, and each of said secondary cyclones having a body, an inlet and an outlet; wherein the outlet of the primary cyclonic separation device is connected to the inlet of at least one secondary cyclone; a first plenum having a skirt and a floor forming a sealed annular chamber within the shell; a second plenum having a smaller volume than a volume of the first plenum; and a secondary cyclone support system minimizing or eliminating mechanical thermal stresses; and wherein the outlets of the plurality of secondary cyclones are fluidly connected to the second plenum is provided.