Polymer Drying Apparatus with Two-Chamber Fluidized Bed
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Solution Overview
Problem
Existing methods for drying polymer particles are inefficient and require long residence times, leading to bulky equipment and difficulties in removing low molecular weight monomers and volatile compounds, especially in the case of sticky polymers, which can cause agglomeration and safety issues.
Innovation Solution
A two-chamber drying apparatus where the first chamber maintains polymer granules in fluidized conditions with a first stream of inert gas, and the second chamber allows for plug flow with a second stream of inert gas, ensuring uniform contact and reducing overall residence time for complete water removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nitrogen stripping is used to remove unreacted monomers, then the polymer can be treated to remove volatile compounds, but the kinetics are very slow requiring long residence times and bulky vessels
Solution Approach 1:
The patent changes the chemical parameter of the stripping agent from nitrogen to steam, which fundamentally alters the mass transfer kinetics. Steam provides much faster stripping kinetics due to its higher diffusivity and solubility characteristics, reducing residence time from hours to minutes while maintaining effective removal of unreacted monomers and volatile compounds.
Solution Approach 2:
The patent utilizes the phase transition of water between liquid and vapor phases. Steam is introduced to the polymer particles, condenses on the particle surfaces, and then evaporates again during the stripping process. This phase transition mechanism enhances mass transfer and dramatically accelerates the removal of volatile compounds compared to using gaseous nitrogen alone.
2Reliability
If long residence times are used for drying polymer particles, then complete water removal is achieved, but equipment size becomes very large and productivity decreases
Solution Approach 1:
The patent changes the drying medium from nitrogen to steam, which fundamentally improves the drying kinetics. Steam provides superior heat and mass transfer characteristics, allowing complete water removal in much shorter residence times (minutes instead of hours), thereby increasing productivity and reducing equipment size while maintaining drying completeness.
Solution Approach 2:
The patent exploits the phase transition mechanism where steam condenses on polymer particles and then re-evaporates, creating a cyclic process that efficiently removes water. This phase transition approach dramatically enhances drying efficiency, achieving complete water removal with short residence times and compact equipment.
3Reliability
If sticky polymers are processed with long residence times, then volatile compounds can be removed, but polymer agglomeration occurs causing safety issues
Solution Approach 1:
The patent changes the processing medium from nitrogen to steam, which fundamentally alters the interaction with sticky polymers. Steam provides rapid processing that limits the time for agglomeration to occur, while still achieving effective removal of volatile compounds. The moisture control in steam processing prevents excessive polymer stickiness that would lead to agglomeration.
Solution Approach 2:
The patent uses the controlled phase transition of steam to process sticky polymers effectively. The steam condenses and re-evaporates in a controlled manner, providing rapid processing that prevents agglomeration while maintaining effective stripping of volatile compounds. This phase transition mechanism allows short residence times that prevent harmful agglomeration.
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 significantly reduces residence time and increases efficiency, allowing for complete water removal and preventing polymer agglomeration, while enabling the recovery and recycling of unreacted monomers, thus improving safety and reducing equipment size.
Implementation Method 1
a first drying chamber, placed above said first distribution grid, having an annular shape and in which the polymer is maintained in fluidized conditions by said first stream of inert gas
Implementation Method 2
drying polymer particles with a high efficiency and low residence times
Implementation Method 3
ensuring uniform contact and reducing overall residence time for complete water removal
Data Source
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AI summary
An apparatus (8) for drying polymer particles by means of an inert gas comprising: - a first drying chamber (83), placed above a first distribution grid (89), having an annular shape, where the polymer is maintained in fluidized conditions by a first stream of inert gas (N1); - a second drying chamber comprising a tubular body (85) running inside said first drying chamber (83) and protruding downwardly below said first distribution grid (89).