Screw-Conveyor Machine for Thermoplastic Recycling with Chloride Conversion
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Solution Overview
Problem
Current methods for processing thermoplastic materials, particularly plastics recycling and waste, are energy-intensive and inefficient due to the need for complex metering systems, limited throughput, and the presence of halogen-containing compounds like PVC, which inhibit pyrolysis and require costly post-treatment.
Innovation Solution
A method and device using a screw-conveyor machine to continuously supply and meter thermoplastic materials, with an additive that converts organic chlorides into inorganic chlorides, allowing for simultaneous plasticizing and mixing, thereby degrading PVC and removing hydrogen chloride, which is then extracted, resulting in a more efficient and energy-effective process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If solid plastics waste is charged to the pyrolysis reactor, then the process can handle mixed polyolefins and PVC, but the process becomes discontinuous and requires complex metering units
Solution Approach 1:
The plastics waste is pre-melted and homogenized in an extruder before being fed to the pyrolysis reactor. This preliminary melting action converts solid waste into a ready-to-process melt, eliminating the need for complex metering units at the reactor feed while maintaining the ability to handle mixed plastics including PVC and polyolefins
2Device complexity
If solid plastics waste is charged discontinuously, then metering complexity is reduced, but energy consumption increases and throughput is limited
Solution Approach 1:
The extruder operates continuously to melt and prepare plastics waste, providing a continuous supply of processed melt to the pyrolysis reactor. This continuous operation eliminates idle time between charging cycles, significantly increasing throughput capacity while maintaining simple charging infrastructure
Solution Approach 2:
By performing melting and homogenization in the extruder before reactor feeding, the system enables continuous processing without requiring complex continuous metering systems at the reactor level, thus achieving high throughput with relatively simple equipment
3Adaptability or versatility
If plastics waste containing PVC is processed, then comprehensive recycling is achieved, but halogens inhibit pyrolysis and require complex post-treatment
Solution Approach 1:
The extruder performs preliminary thermal processing that begins the degradation of PVC and release of hydrogen chloride before the material enters the pyrolysis reactor. This pre-treatment reduces the halogen content and inhibition effect on subsequent pyrolysis, enabling comprehensive recycling of mixed plastics including PVC without complex post-treatment
Solution Approach 2:
The system rapidly processes through the PVC degradation stage in the extruder, quickly converting halogen-containing plastics and releasing hydrogen chloride before pyrolysis. This rapid transition minimizes the inhibitory effect of halogens on the pyrolysis process while maintaining the ability to recycle all plastic types
4Productivity
If multiple extruders and pyrolysis reactors are used to increase throughput, then processing capacity is sufficient, but the process becomes uneconomical and energy-intensive
Solution Approach 1:
The extruder is designed to perform multiple functions: melting plastics waste, homogenizing the melt, pre-degrading PVC to release hydrogen chloride, and preparing the material for pyrolysis. This multi-functionality allows a single extruder to handle high throughput without requiring multiple reactors, reducing energy consumption and equipment costs while maintaining high productivity
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 enhances energy efficiency, increases throughput, and reduces the need for external heating, allowing for continuous processing with minimal chloride passage into pyrolysis, thus improving the overall efficiency and cost-effectiveness of the plastics recycling process.
Implementation Method 1
The screw-conveyor machine is designed to plasticize supplied plastics material to form a plastics melt
Implementation Method 2
The treatment element shafts are designed to rotate in the same direction and to intermesh
Implementation Method 3
an additive for converting organic chlorides into inorganic chlorides... allowing for simultaneous plasticizing and mixing, thereby degrading PVC
Implementation Method 4
The treatment element shafts are designed to mix the plastics melt with the supplied additive to form a mixture
Implementation Method 5
The plastics melt or the mixture formed is degassed in the screw-conveyor machine by means of at least one degassing device arranged on the screw-conveyor machine
Data Source
AI summary
A method for processing plastics material, in particular thermoplastic material, such as plastics recycling material and/or plastics waste, is disclosed comprising the following steps: supplying the plastics material into a screw-conveyor machine); supplying an additive for converting organic chlorides into inorganic chlorides into the screw-conveyor machine; plasticizing the supplied plastics material with the screw-conveyor machine to form a plastics melt, and mixing the plastics melt with the supplied additive with the screw-conveyor machine to form a mixture, wherein at least some of the organic chlorides contained in the plastics melt are converted into inorganic chlorides with the additive. A corresponding device for processing plastics material, in particular thermoplastic material, such as plastics recycling material and/or plastics waste, using a screw-conveyor machine is also disclosed.