PET Flake Decontamination and SSP Reactor System
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Solution Overview
Problem
Current recycling methods for PET plastics, such as DE 199 53 659 A1, require high energy consumption for heating and continuous recondensation, making it difficult to maintain or increase the intrinsic viscosity (IV) of recycled PET flakes, which limits their reuse in applications like beverage bottles.
Innovation Solution
A method and device that utilize a decontamination and solid-state polycondensation (SSP) treatment in separate reactors under adiabatic conditions, where flakes are heated externally before entering the reactors, allowing for controlled IV adjustment and reduced energy consumption by minimizing heating within the reactors, and using a gas stream for decontamination and inert gases for SSP to prevent chain elongation or shortening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PET flakes are heated in reactors for continuous recondensation, then the intrinsic viscosity increases, but energy consumption increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-heating the PET flakes in a fluidized bed dryer before they enter the reactor. This pre-heating prepares the material in advance, reducing the heating energy required during the actual recondensation process in the reactor, thereby resolving the contradiction between achieving desired intrinsic viscosity and minimizing energy consumption
Solution Approach 2:
The patent implements periodic action by operating the reactor in batch mode rather than continuous operation. The reactor is filled, processed, emptied, and refilled in cycles. This allows for optimized heating and processing periods, reducing overall energy consumption while maintaining the necessary intrinsic viscosity levels for quality recycled PET
2Productivity
If continuous recondensation is performed in a shaft reactor, then processing efficiency increases, but control over intrinsic viscosity becomes imprecise
Solution Approach 1:
The patent applies segmentation by dividing the processing into distinct stages: pre-heating in a fluidized bed dryer, then batch-wise processing in the shaft reactor. This segmentation allows for better control at each stage, particularly enabling precise control of residence time and temperature in the reactor batch process, thereby achieving both good productivity and precise intrinsic viscosity control
Solution Approach 2:
The patent implements dynamics by allowing flexible adjustment of processing parameters in the batch reactor approach. Operators can dynamically adjust residence time, temperature profiles, and batch sizes based on the specific requirements of different PET flake batches, enabling precise control of intrinsic viscosity while maintaining efficient processing
3Power
If hot gas is used for heat transfer in the reactor, then heating efficiency improves, but system complexity increases due to gas preparation requirements
Solution Approach 1:
The patent applies self-service by using the PET flakes themselves as the heat transfer medium in the fluidized bed dryer. The flakes are circulated through the heating zone, absorbing heat directly, and then distributed back into the reactor. This eliminates the need for separate hot gas generation and circulation systems, reducing device complexity while maintaining effective heat transfer and drying functionality
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 energy consumption, allows for precise control of IV, and enables the reuse of recycled PET flakes in food packaging applications by maintaining or adjusting their molecular structure without continuous heating, thus enhancing their processability and quality.
Implementation Method 1
the heating of the flakes to be treated to the process temperature is carried out in a heating installation
Implementation Method 2
a hot gas flows around the flakes during the decontamination step
Implementation Method 3
a hot gas flows around the flakes during the decontamination step
Implementation Method 4
The gas pressure in the reactor is reduced by means of a vacuum pump
Implementation Method 5
If nitrogen or carbon dioxide is used as protective gas, the process can be carried out particularly well
Data Source
AI summary
A method for preparing contaminated plastics ground into flakes, such as RPET or such polymers, having at least decontamination and SSP treatment steps, with at least one reactor, with heating to the process temperature taking place essentially outside the reactor. Also, a device for carrying out the method, and having at least one decontamination reactor and at least one SSP reactor, a device for heating plastic flakes to the process temperature being arranged upstream of the decontamination reactor. Also an SSP reactor having at least two individual reactors, and preferably between 3 and 7 individual reactors.