Pyrolysis Oil Aromatics Recovery via Extractive Distillation
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Solution Overview
Problem
Existing combined facilities for waste plastic pyrolysis and downstream cracking processes often fail to efficiently recover valuable recycle content products from the pyrolysis effluent, leading to process deficiencies and reduced product recovery.
Innovation Solution
A chemical recycling process involving the thermal pyrolysis of waste plastic, followed by condensation to separate pyrolysis oil and gas streams, and then further processing to enrich aromatics and diolefins in an extract stream, which is then introduced into a cracker furnace along with a raffinate stream to enhance recycle content product recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pyrolysis facilities are added to existing downstream cracking facilities, then waste plastic can be converted to chemical feedstocks, but valuable recycle content products from pyrolysis effluent are broken down in downstream processes and not sufficiently recovered
Solution Approach 1:
The integrated facility is segmented into distinct functional zones: a pyrolysis zone for waste plastic decomposition, a condensation zone for product recovery, and a cracking zone for feedstock processing. This spatial segmentation allows valuable pyrolysis products to be recovered before entering the cracking process, preventing their breakdown while maintaining overall conversion efficiency
Solution Approach 2:
The condensation process is performed preliminarily before the cracking process. By condensing and recovering valuable recycle content products from pyrolysis effluent prior to introducing them into the cracking furnace, the system preserves these products that would otherwise be broken down during high-temperature cracking operations
2Loss of substance
If direct recovery of desirable recycle products from pyrolysis effluent is implemented, then product recovery improves, but process complexity increases due to additional separation and enrichment steps
Solution Approach 1:
The separation and enrichment functions are merged into a unified extraction system that operates within the existing facility framework. The extractive distillation unit combines separation of valuable products from pyrolysis effluent with enrichment of aromatics and diolefins in a single integrated process train, reducing overall system complexity compared to multiple separate units
Solution Approach 2:
An extractive distillation intermediary system is introduced to facilitate the separation of valuable recycle content products from pyrolysis effluent. This intermediary extraction process uses selective solvents or adsorbents to capture aromatics and diolefins, simplifying the separation task compared to direct physical separation methods
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 optimizes the recovery and utilization of valuable recycle content products from waste plastics by directly separating and enriching aromatics and diolefins, thereby improving the efficiency of product recovery in combined pyrolysis and cracking facilities.
Implementation Method 1
thermally pyrolyzing waste plastic to produce a pyrolysis oil stream
Implementation Method 2
condensing at least a portion of the pyrolysis effluent to thereby form a pyrolysis oil stream and a pyrolysis gas stream
Data Source
AI summary
It has been discovered that high volumes of valuable recycle content products may be directly derived from waste plastic pyrolysis effluent. More particularly, one or more valuable recycle content hydrocarbons, such as aromatics and diolefins, can be separated from recycle content pyrolysis oil prior to further treatment in a downstream cracker facility. Consequently, by recovering these valuable recycle content products upstream of the cracking facility, one can optimize recovery and utilization of recycle content products from waste plastics.