Underwater Pelletizing System for Polymer Crystallization
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Solution Overview
Problem
Existing methods for pelletizing polymers like polyesters, polyamides, and polycarbonates often result in amorphous structures that require additional heating steps for crystallization, which is inefficient and costly.
Innovation Solution
An underwater pelletizing system that injects high-velocity air or inert gas into the pellet slurry to rapidly transport pellets through a dryer, retaining latent heat for self-initiated crystallization, eliminating the need for secondary heating and ensuring sufficient crystallinity without agglomeration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional pelletizing methods are used, then the process is simple, but the polymer pellets remain amorphous and require additional heating steps for crystallization
Solution Approach 1:
The patent utilizes phase transition by injecting high-velocity gas into the water slurry to rapidly evaporate water and transfer latent heat to the polymer pellets, inducing crystallization from amorphous to crystalline state during the drying process itself
Solution Approach 2:
The patent employs pneumatic principles by using high-velocity gas injection through nozzles into the water slurry to create rapid water evaporation and achieve efficient heat transfer to the pellets for crystallization
2Productivity
If additional heating steps are used for crystallization, then sufficient crystallinity is achieved, but processing time and costs increase
Solution Approach 1:
The patent implements self-service by using the latent heat from water evaporation to provide the necessary heat for crystallization, eliminating the need for external heating systems and reducing both processing time and energy consumption
Solution Approach 2:
The patent exploits the phase transition of water from liquid to vapor, utilizing the latent heat released during evaporation to crystallize the polymer pellets in situ, thereby eliminating separate heating steps and reducing overall processing time
3Productivity
If pellets are rapidly transported through the dryer, then latent heat is retained for crystallization, but residence time in water slurry is reduced
Solution Approach 1:
The patent uses phase transition of water to vapor as a rapid mechanism to remove water from pellets while simultaneously providing latent heat for crystallization, achieving both rapid drying and crystallization in a short residence time
Solution Approach 2:
The patent employs periodic or pulsed gas injection to create intermittent high-velocity flows that rapidly evaporate water and promote crystallization during the brief residence time in the dryer, optimizing both speed and crystallization efficiency
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 system achieves crystallization of 30% or greater in polymer pellets without additional heating, reducing processing time and costs, and preventing agglomeration during further processing.
Implementation Method 1
An underwater pelletizing system that injects high-velocity air or inert gas into the pellet slurry to rapidly transport pellets through a dryer
Implementation Method 2
retaining latent heat for self-initiated crystallization
Implementation Method 3
self-initiated crystallization
Implementation Method 4
preventing agglomeration during further processing
Data Source
AI summary
A method and apparatus for underwater pelletizing and subsequent drying of crystallizing polymers to crystallize the polymer pellets with out subsequent heating is shown in FIG. 5. High velocity air or other inert gas is injected into the water and pellet slurry line (120) toward the dryer near the pelletizer exit (102) at a flow rate from about 100 to about 175 m3/hour, or more. Such high-speed air movement forms a vapor mist with the water and significantly increases th speed of the pellets into and out of the dryer such that the polymer pellets leave the dryer with sufficient latent heat to cause self-crystallization within the pellets. A valve mechanism in the slurry line (150) after the gas injection further regulates the pellet residence time and a vibrating conveyor after the dryer helps the pellets to achieve the desired level of crystallinity and to avoid agglomeration.