Truncated Cone Plates for Bubble Fragmentation in Fluidized Beds
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Solution Overview
Problem
Three-phase ebullated bed reactors face challenges in preventing the entrainment of solid particles by large gas bubbles, leading to catalyst loss and reduced reactor capacity.
Innovation Solution
A device comprising flat or truncated cone-shaped plates, arranged vertically and inclined at specific angles, is placed between the solid expansion level and the liquid phase to fragment large bubbles and prevent solid particle entrainment, with a cross-sectional area that is 1 to 10 times the outlet pipework area, and holes to break up bubbles and minimize pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas velocity is increased to enhance reactor capacity, then productivity improves, but solid particle entrainment increases
Solution Approach 1:
The device segments the gas flow path by introducing multiple plates arranged in series, which divide large bubbles into smaller bubbles. This segmentation reduces the entrainment capability of individual bubbles while maintaining overall gas flow rate, thereby increasing reactor capacity without proportionally increasing catalyst loss.
Solution Approach 2:
The plates act as intermediary elements between the gas phase and solid particles. By introducing this intermediate structure, the device modifies the gas-bubble-solid interaction, reducing direct entrainment while allowing gas to pass through. The plates serve as a mediator that decouples gas flow rate from particle entrainment.
2Loss of substance
If plate area is increased to reduce entrainment, then catalyst loss decreases, but device complexity increases
Solution Approach 1:
The device applies local quality by positioning plates at specific locations within the reactor rather than uniformly throughout. The plates are strategically placed to intercept large bubbles at critical points where entrainment occurs, providing localized intervention that reduces catalyst loss without requiring comprehensive structural modification of the entire reactor.
Solution Approach 2:
The device uses partial action by incorporating only the necessary number of plates to achieve effective bubble fragmentation. Rather than filling the entire reactor volume with plates, the design uses a limited number of plates arranged in a sequence that provides sufficient resistance to entrainment while minimizing device complexity and maintaining manageable structure.
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 allows for higher superficial gas velocities without increasing catalyst loss, enhancing reactor capacity and reducing solid particle entrainment by up to a factor of 2, particularly at gas velocities above 4 cm/s.
Implementation Method 1
a device for limiting entrainment of solid particles at the outlet from a three-phase fluidized bed... intended to receive the three-phase liquid-gas-solid mixture... geometry suitable for fragmenting the bubbles of the gas phase
Implementation Method 2
preventing entrainment of solid particles by this gas phase... plates inclined at an angle with respect to the horizontal
Data Source
AI summary
The present invention concerns a device for limiting the entrainment of solid particles placed inside a three-phase fluidized reactor, said device being constituted by an assembly of flat or truncated cone-shaped plates ranked vertically in one or more rows, and the maximum horizontal cross section area of the device being in the range 1 to 10 times the horizontal cross section area of the outlet pipework for the gas effluents. It also concerns a three-phase process employing said device.