Parallel Moving Bed Reactors for PET Pellet Production
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Solution Overview
Problem
Existing methods for producing PET granules for packaging film and bottles require large investment costs and result in significant waste due to the need for single-product campaigns, leading to high storage requirements and inefficiencies in production capacity.
Innovation Solution
A method and system involving multiple moving bed tube reactors for post-treatment of PET granules, allowing for individual adjustment of residence time, process gas composition, and temperature to produce multiple polymer qualities simultaneously, enabling continuous production with parallel operation of granulation and crystallization systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single-product campaigns are used to ensure production capacity, then large storage capacity is required, but this leads to significant waste when changing product quality
Solution Approach 1:
The aftertreatment system is divided into multiple parallel moving bed tube reactors, each capable of producing different polymer qualities simultaneously. This segmentation allows continuous production of multiple product specifications without campaign changes, eliminating waste associated with product switching while maintaining high production capacity.
Solution Approach 2:
Each moving bed tube reactor is designed with universal capabilities to produce different polymer qualities by adjusting process parameters (residence time, process gas composition, temperature). This multi-functionality enables a single reactor configuration to handle multiple product specifications, reducing the need for large storage facilities and minimizing waste during product transitions.
2Ease of manufacture
If single-strand continuous polymerization system is used, then investment costs are high, but production capacity is limited
Solution Approach 1:
The polymerization system is segmented into multiple parallel single-strand continuous polymerization reactors. Each reactor operates independently at high capacity, and their outputs are combined in the granulation and aftertreatment stages. This segmentation increases total production capacity while maintaining the cost-effectiveness of single-strand design, avoiding the need for expensive multi-strand systems.
Solution Approach 2:
Multiple high-capacity single-strand polymerization reactors are merged at the granulation and aftertreatment stages through parallel processing lines. This combining approach achieves the aggregate production capacity of large multi-strand systems while retaining the investment advantages of smaller, simpler single-strand units.
3Loss of substance
If multiple polymer qualities are produced simultaneously, then waste and storage needs are reduced, but this requires complex parallel reactor systems
Solution Approach 1:
The system is segmented into standardized modular moving bed tube reactors that can be replicated in parallel. Each module is identical in design but operates with different process parameters to produce different polymer qualities. This modular segmentation reduces overall system complexity compared to designing a completely integrated multi-product system, as each reactor is a self-contained, proven technology unit.
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 allows for efficient production of multiple polymer qualities in parallel, reducing waste and storage needs, and enabling continuous operation with high production capacity, thus enhancing economic viability and reducing production costs.
Implementation Method 1
granulation of the melt with cooling to form a raw granulate, with partial crystallization of the polymer taking place with the release of part of the heat of crystallization of the polymer (latent heat crystallization)
Implementation Method 2
the aftertreatment takes place in several moving bed tube reactors operated in parallel, the residence time of the granules in the reactor, the type and chemical composition of the process gas, and its temperature and dew point at the entry into the reactor can be set individually for each of the reactors
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a process and installation for the production of polyethylene terephthalate (PET) pellets by transesterification of dimethyl terephthalate with ethylene glycol, or by esterification of (fibre-) pure terephthalic acid with ethylene glycol, suitable for the further processing to packaging film and bottles, comprising the steps of polycondensation, granulation and latent heat crystallization, post-treatment of the raw granules for setting the polymer quality values which are required for further processing, in particular the intrinsic viscosity, the acetaldehyde and moisture content, wherein the post-treatment is carried out in a plurality of moving bed tubular reactors which are operated in parallel.