Waste Plastic Pyrolysis Oil Upgrading via FCC Pretreater
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Solution Overview
Problem
Current methods for recycling polyethylene and polypropylene waste plastics into value-added chemical and fuel products are inefficient, producing poor-quality fuel components that cannot be blended in large quantities, limiting their environmental impact and industrial significance.
Innovation Solution
A continuous process integrating pyrolysis of waste plastics with oil refinery operations, including a FCC Feed Pretreater Unit to remove contaminants and upgrade pyrolysis oil and wax into higher-value products like gasoline and diesel, and utilizing steam cracking to produce pure ethylene for polyethylene polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If simple pyrolysis is used to convert waste plastic into fuel components, then the process is simple and easy to operate, but the product quality is poor and cannot be blended in large quantities
Solution Approach 1:
The patent divides the single pyrolysis process into multiple sequential processing stages: pyrolysis unit → distillation unit → blending unit. This segmentation allows each unit to perform a specific function optimally, with the distillation unit upgrading the crude pyrolysis oil into quality fuel components that meet blending specifications.
Solution Approach 2:
The patent introduces a distillation unit as an intermediary between the pyrolysis unit and the final fuel product. This intermediary process separates and purifies the pyrolysis oil into different fractions, removing impurities and producing high-quality fuel components that can be blended in large quantities.
2Quantity of substance
If large volumes of waste polyethylene and polypropylene are recycled via simple pyrolysis, then the environmental impact is addressed, but the product quality is too poor for large-scale blending in transportation fuels
Solution Approach 1:
The patent applies preliminary action by performing distillation and purification of pyrolysis oil before blending. The distillation unit pre-processes the crude pyrolysis oil to remove impurities and produce high-quality fuel components, ensuring that even large volumes meet the required specifications for transportation fuel blending.
Solution Approach 2:
The patent changes the physical and chemical parameters of the pyrolysis oil through controlled distillation at different temperature ranges. This separates the oil into light ends, gasoline range, diesel range, and heavy ends, with each fraction having optimized quality parameters suitable for specific fuel applications and blending ratios.
3Productivity
If current pyrolysis operations produce fuel components for blending, then some environmental benefit is achieved, but the quantity is too small to make a big impact on the plastics industry
Solution Approach 1:
The patent creates a multi-functional integrated system that can process large volumes of waste plastic while producing multiple valuable products: high-quality fuel components for blending, chemical feedstocks, and potential polymer recyclate. This universality allows the system to handle industrial-scale waste volumes and make a significant impact on the plastics industry.
Solution Approach 2:
The patent establishes a continuous processing system where waste plastic is continuously converted through pyrolysis, distillation, and blending operations. This continuous operation enables high-volume throughput and sustained productivity, allowing large quantities of waste plastic to be recycled regularly rather than in batch processes.
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 process enables the recycling of large quantities of polyethylene and polypropylene waste into high-quality fuels and polymers, establishing a circular economy with product quality identical to virgin polymers, reducing virgin feed requirements and enhancing environmental sustainability.
Implementation Method 1
passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent
Implementation Method 2
This unit is effective in removing sulfur, nitrogen, phosphorus, silica, dienes and metals that will hurt a FCC unit catalyst performance
Implementation Method 3
The heavy fraction is sent to an FCC unit for further production of C3, C4, FCC gasoline and heavy fraction
Implementation Method 4
The C3 stream is fed to a steam cracker to be converted to pure ethylene
Data Source
AI summary
Provided in one embodiment is a continuous process for converting waste plastic into recycle for polyethylene polymerization. The process comprises selecting waste plastics containing polyethylene and/or polypropylene, and passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is separated into offgas, a pyrolysis oil and optionally pyrolysis wax comprising a naphtha/diesel fraction and heavy fraction, and char. The pyrolysis oil and wax is passed to a refinery FCC feed pretreater unit. A heavy fraction is recovered and sent to a refinery FCC unit, from which a C3 olefin/paraffin mixture fraction is recovered, which is passed to a steam cracker for ethylene production. In another embodiment, a propane fraction (C3) is recovered from a propane/propylene splitter and passed to the steam cracker.