Pyrolysis Oil Processing via Stream Segmentation and Desulfurization
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Solution Overview
Problem
Current systems lack efficient methods to process pyrolysis oil from plastic waste into chemicals or polymers, often resulting in the use of valuable fractions as fuel due to contamination and inefficiencies in cracking and catalytic reforming processes.
Innovation Solution
A system comprising a feed line, feed fractionator, hydrotreater, catalytic reforming unit, heavy oil cracker, and steam cracker, which separates pyrolyzed plastics into light, medium, and heavy hydrocarbon streams, desulfurizes and catalytically reforms the medium stream, and cracks and steam cracks the heavy stream to produce aromatic-rich and olefin streams, reducing contamination and maximizing the recovery of useful fractions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pyrolysis oil is processed using conventional cracking and catalytic reforming methods, then some chemicals can be produced, but valuable fractions are lost due to contamination and inefficiencies
Solution Approach 1:
The system segments pyrolysis oil into three distinct hydrocarbon streams (light C5 or lower, medium C6-C8, and heavy C9 or higher) based on carbon number ranges. This segmentation allows each stream to be processed through optimized pathways, preventing the mixing and contamination that causes valuable fraction loss in conventional systems.
Solution Approach 2:
The system performs preliminary fractionation and desulfurization before catalytic reforming. By removing sulfur contaminants early in the process through the hydrotreater unit, the subsequent catalytic reforming operates more efficiently, preventing contamination-related losses of valuable aromatic fractions.
2Quantity of substance
If pyrolysis oil contains contaminants from recycled plastics, then the feedstock is readily available, but the contaminants reduce the effectiveness of processing
Solution Approach 1:
The system extracts harmful sulfur contaminants from the medium hydrocarbon stream through the hydrotreater unit. This extraction removes the contaminant that would otherwise poison catalysts and reduce processing effectiveness, while preserving the valuable hydrocarbon components for further conversion to chemicals and polymers.
Solution Approach 2:
The hydrotreater acts as an intermediary unit between fractionation and catalytic reforming. It mediates the conflict between contaminated feedstock and sensitive catalysts by providing a cleaned intermediate stream, enabling reliable processing despite the presence of contaminants in the original pyrolysis oil.
3Device complexity
If conventional processing methods are used, then the process is simpler, but more fractions must be used as fuel rather than chemicals
Solution Approach 1:
By segmenting the pyrolysis oil into three carbon-number-based streams, the system enables targeted processing pathways that convert more fractions into valuable chemicals (aromatics from medium stream, olefins from heavy stream) rather than burning them as fuel. The additional complexity of segmentation is offset by the elimination of fuel combustion steps.
Solution Approach 2:
The system changes the processing parameters for different hydrocarbon streams based on their carbon number characteristics. Light streams undergo catalytic reforming to produce aromatics, while heavy streams undergo cracking to produce olefins. This parameter-based differentiation maximizes chemical recovery across all fractions.
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 effectively extracts a larger number of useful fractions from pyrolysis oil, reducing the need to use them as fuel and enhancing the production of circular monomers and polymers, thereby increasing the recycling of plastic waste into higher-value plastic materials.
Implementation Method 1
a feed fractionator coupled to the feed line for separating the pyrolyzed plastics feed into a light hydrocarbon stream, a medium hydrocarbon stream, and a heavy hydrocarbon stream
Implementation Method 2
The hydrotreater is fluidically coupled to the feed fractionator to receive the medium hydrocarbon stream and configured to desulfurize the medium hydrocarbon stream
Implementation Method 3
The catalytic reforming unit includes a zeolitic reforming catalyst comprising platinum on a bound zeolite support. The catalytic reforming unit is fluidically coupled to the hydrotreater to receive the circular hydrotreated hydrocarbon stream and produce a circular aromatic-rich stream
Implementation Method 4
The heavy oil cracker is fluidically coupled to the feed fractionator to receive the heavy hydrocarbon stream and generate a first cracked stream including C6 or higher circular hydrocarbons and a second cracked stream including C5 or lower circular hydrocarbons
Implementation Method 5
The steam cracker is fluidically coupled to the heavy oil cracker to receive the first cracked stream and produce a circular olefin stream
Data Source
AI summary
A system for processing plastic waste may include a feed line, a feed fractionator, a hydrotreater, a catalytic reforming unit, a heavy oil cracker, and a steam cracker. A pyrolyzed plastics feed is separated into light, medium, and heavy hydrocarbon streams. The hydrotreater removes sulfur, and the catalytic reforming unit produces a circular aromatic-rich stream. The heavy oil cracker generates cracked streams. The steam cracker produces a circular olefin stream from a cracked stream. A system for processing plastic waste may include the feed line, the feed fractionator, the hydrotreater, a medium hydrocarbon fractionator, the catalytic reforming unit, a full-range reforming unit, the heavy oil cracker, and the steam cracker. The medium hydrocarbon fractionator produces two hydrocarbon streams. The full-range naphtha reforming unit produces a second circular aromatic-rich stream.