THE CHALLENGE:
Poly(ethylene terephthalate) (PET) is extensively used in packaging, textiles, and various consumer goods. The recycling of PET reduces the consumption of materials to produce the virgin PET and processes recycling PET have the potential to provide economic value. Supply chains and the economic incentive to collect and recycle waste PET reduces the consumption of fossil fuel derived feedstock and reduces the rate of mismanaged PET waste contributing to the growing global plastic waste problem. Chemical recycling methods, such as hydrolysis producing TPA from PET, aid this effort, by breaking down PET into its original monomers that can be conveniently purified, enabling the production of high-quality recycled materials from low-purity PET waste, drastically expands the scope of recoverable PET waste.
Current PET chemical recycling technologies face challenges that hinder their effectiveness and efficiency. Traditional hydrolysis processes often suffer from low efficiency in separating and recovering key components such as ethylene glycol (EG) and terephthalic acid (TPA), resulting in significant material losses and increased operational costs. Most hydrolysis units use alkaline hydroxides and managing the salt byproduct is energy-intensive and generates environmental waste, increasing the overall ecological footprint. High energy consumption and water usage in these processes further limit their viability, while impurity handling remains a persistent issue, affecting the quality of the reclaimed monomers. These limitations highlight the need for more efficient, energy-saving, and environmentally friendly recycling methods to overcome the shortcomings of existing PET depolymerization techniques.
OUR SOLUTION:
The technology provides an energy-efficient method for concentrating salt byproducts generated during the depolymerization of poly(ethylene terephthalate) (PET). It utilizes a four-stage multi-effect evaporation system designed to process dilute salt solutions with concentrations ranging from 4-15 wt%. The system incorporates advanced feed handling and preparation, including preheating through heat integration with concentrated product streams and condensed water. It offers flexible operational configurations for feed introduction and employs progressive pressure reduction across successive stages. The design includes options for vapor condensation using cooling water or air, vertical stacking or separate vessels for inter-stage connections, and vacuum purge lines for non-condensable gases. Additionally, the system features multiple parallel adsorbent beds to enable continuous operation, produces highly concentrated salt solutions of 10-50 wt%, and recycles condensed water for process reuse, enhancing overall efficiency.
This technology distinguishes itself from traditional concentration methods such as electrolysis or crystallization by significantly reducing energy consumption through the use of multi-effect evaporation, which minimizes the reliance on water’s high heat of vaporization. The integration of heat between process streams and the flexible operational configurations allow for adaptability to various operating conditions while maintaining optimal performance. Water recycling capabilities further enhance sustainability by lowering water consumption, and the continuous operation potential provided by parallel adsorbent beds ensures economic viability. These features collectively offer a more sustainable and cost-effective solution for managing salt byproducts in PET recycling operations, addressing both energy efficiency and practical operational needs.
ADVANTAGES:
- Significantly reduces energy consumption through multi-effect evaporation
- Enhances efficiency compared to traditional electrolysis and crystallization methods
- Integrates heat streams for preheating and heat recovery, optimizing energy use
- Offers flexible operational configurations for varied processing needs
- Enables water recycling, minimizing water consumption
- Supports continuous operation with parallel adsorbent bed design
- Efficient salt concentration
- Provides solutions for separating excess alkaline hydroxide and salt from volatiles
- Provides a sustainable and economically viable solution for PET recycling
- Adaptable to different operating conditions while maintaining optimal performance
POTENTIAL APPLICATIONS:
- PET Recycling Plants
- Chemical Manufacturing
- Polyester Production
- Waste Management Services
- Circular Economy Initiatives
