Stream Dryer Pre-Drying PET Waste for Multi-Screw Recycling
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Solution Overview
Problem
The recycling of PET waste material is hindered by its high moisture content, which impairs processing in multi-shaft screw machines, leading to inefficiencies and increased costs due to the need for extensive drying and degassing.
Innovation Solution
A method involving a stream dryer to quickly and gently dry PET waste material before processing, using a conveying gas to pre-dry the material, reducing moisture content and minimizing stress on the plastic, allowing for efficient recycling with lower investment and operating costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PET waste material is washed to clean it, then purity is improved, but moisture content increases which impairs subsequent recycling processing
Solution Approach 1:
A stream dryer is integrated into the conveying line to pre-dry the washed PET waste material before it enters the multi-shaft screw machine. This preliminary drying action removes excess moisture immediately after washing, preventing the moisture-related processing problems that would otherwise occur during recycling.
2Quantity of substance
If extensive drying is applied to remove moisture from PET waste material, then moisture content is reduced, but energy consumption increases
Solution Approach 1:
The stream dryer performs preliminary drying in the conveying line, removing the bulk of moisture before the material enters the multi-shaft screw machine. This preliminary action significantly reduces the moisture load, thereby minimizing the energy required for any subsequent drying or degassing operations in the recycling process.
Solution Approach 2:
The stream dryer uses a conveying gas stream (pneumatic method) to dry the PET waste material during transport. This pneumatic drying approach is more energy-efficient than traditional thermal drying methods, as it removes moisture during the conveying process without requiring additional high-energy heating stages.
3Ease of operation
If high moisture content PET waste material is processed in a multi-shaft screw machine, then processing can begin immediately, but throughput decreases due to foaming and clogging
Solution Approach 1:
The stream dryer is positioned in the conveying line immediately before the multi-shaft screw machine, performing preliminary drying right at the point of processing. This ensures that the material enters the screw machine with minimal moisture content, preventing foaming and clogging issues while maintaining continuous operation and high throughput.
4Quantity of substance
If a large degassing device is used to remove moisture during recycling, then moisture removal capability is improved, but device complexity and investment costs increase
Solution Approach 1:
The stream dryer performs the majority of moisture removal in advance, before the material enters the multi-shaft screw machine. This preliminary drying action dramatically reduces the moisture load that the degassing device must handle, allowing for a smaller, simpler, and more cost-effective degassing system while still achieving the required moisture removal capability.
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 enables energy-efficient, reliable, and economical recycling of PET waste by reducing the moisture content, allowing for higher throughput and quality of recycled material, as well as smaller degassing device requirements.
Implementation Method 1
The stream dryer conveys the waste plastic material in a conveying direction in the conveying line. The stream dryer is arranged in the conveying direction in front of the multi-shaft screw machine, so that the plastic waste material is dried or pre-dried by means of a conveying gas before being reprocessed.
Implementation Method 2
The plastic waste material is dried quickly and easily in the conveying line by means of the stream dryer. Due to the short dwell time of the plastic waste material in the conveyor line, drying is energy-efficient and gentle on the plastic waste material.
Data Source
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AI summary
In a process for reprocessing plastic waste material (Mw), in particular PET waste material, the plastic waste material (Mw) is dried in a conveying line (7) using a stream dryer (5) and then fed into a multi-screw machine (2). The dried plastic waste material (MD) is reprocessed in the multi-screw machine (2). The pre-drying enables simple, energy-efficient, economical, reliable, and effective reprocessing.