Closed Air Circuit for Drying and Crystallizing Polymeric Granulate
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Solution Overview
Problem
Existing methods for drying and crystallizing granules washed with water are costly and require significant installation effort, often necessitating separate circuits for gas recirculation and relying on additional heating sources, which limits their applicability and efficiency.
Innovation Solution
A method and device that utilize a closed air circuit for recirculating exhaust air from a pre-dryer to a dryer/crystallizer, with air conditioning means to produce temperature-controlled and moisture-conditioned air, reducing the need for multiple air conditioning systems and allowing for energy reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate circuits for recirculation and processing of treatment gas are provided for both fluidized bed and bubbled bed, then the drying and crystallization process can be performed, but the installation effort and system and operating costs increase
Solution Approach 1:
The patent combines the recirculation circuits for the fluidized bed and bubbled bed into a single integrated air circuit. The air conditioner serves both drying and crystallization stages, and the exhaust air from the crystallizer is recirculated back to the dryer, eliminating the need for separate recirculation systems for each unit operation.
Solution Approach 2:
The air conditioner is designed to serve multiple functions: it conditions air for the dryer, provides recirculation air for the crystallizer, and handles exhaust air from both units. This multi-functional approach replaces what would traditionally require separate dedicated systems for each process stage.
2Ease of operation
If exhaust air from the pre-dryer is not reused, then the system operation is simplified, but the thermal energy contained in the exhaust air remains unused
Solution Approach 1:
The patent converts the waste thermal energy in the exhaust air from the pre-dryer into a useful resource by recirculating it back to the dryer. The exhaust air, which would otherwise be discarded, is reused to provide additional drying capacity and reduce the energy demand of the air conditioner.
Solution Approach 2:
Instead of discarding the exhaust air from the pre-dryer, the system recovers its thermal energy by routing it back to the dryer inlet. This recovery process reduces the overall energy consumption of the drying system while maintaining operational simplicity.
3Loss of energy
If a silo is included in the system to flush the pre-dryer, then the exhaust air can be utilized, but the installation outlay increases and the system becomes less versatile
Solution Approach 1:
The patent extracts the essential function of exhaust air recirculation from the complex silo-based system and implements it directly through a simplified air circuit configuration. The recirculation is achieved by directly routing exhaust air from the pre-dryer back to the dryer inlet, eliminating the need for intermediate storage and complex flushing operations.
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 reduces installation and operating costs by reusing thermal energy and simplifying system integration, making the process more versatile and efficient.
Implementation Method 1
The air conditioning means produce temperature-controlled and moisture-conditioned air, e.g. hot, dry or e.g. also cooled and/or slightly humidified
Implementation Method 2
pre-drying the granules in the pre-dryer
Implementation Method 3
An injection condenser is installed downstream of the pre-dryer in order to extract the water vapor from the exhaust air of the pre-dryer
Implementation Method 4
discharging crystallized granules from the dryer/crystallizer
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method and a device for continuously drying and crystallizing granulate which is flushed with water. The method has the steps of feeding granulate (11) which is flushed with water into a pre-dryer (20); pre-drying the granulate in the pre-dryer; conveying the pre-dried granulate (21) into a dryer/crystallizer (30); and dispensing crystallized granulate (31) out of the dryer/crystallizer. Air conditioning means (40) generate air (42) which is temperature-controlled and the degree of humidity of which is conditioned, and said air is fed to the dryer/crystallizer. The exhaust air (32) of the dryer/crystallizer is fed to the pre-dryer, and the exhaust air (22) of the pre-dryer is returned to the air conditioning means such that a closed air circuit is formed by the dryer/crystallizer, pre-dryer, and the air-conditioning means.