Plastic-Derived Liquid Steam Cracking Without Feed Pretreatment
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Solution Overview
Problem
Existing methods for converting plastic-derived feedstock into valuable products require significant capital expenditures due to multiple processing steps and catalysts, and are limited by coking issues with feedstocks having boiling points above 370°C.
Innovation Solution
Direct steam cracking of plastic-derived liquid feedstock with a final boiling point of 550°C or less and olefin content of 40 wt% or less, without prior hydrotreating or fractionation, using a quench oil to cool the cracked product from 750°C to 350°C to prevent fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrotreating and fractionation are performed on plastic-derived liquid feedstock before steam cracking, then coking issues are prevented and olefin content requirements are met, but capital expenditures and process complexity increase significantly
Solution Approach 1:
The patent extracts and removes the problematic pre-treatment steps (hydrotreating and fractionation) from the process flow. By directly feeding plastic-derived liquid feedstock into the steam cracker without these intermediate steps, the invention eliminates the associated capital expenditures and process complexity while managing coking through operational parameters like feed rate control and furnace design
Solution Approach 2:
The invention changes the operational parameters of the steam cracking process to accommodate direct feedstock input. This includes adjusting temperature profiles, residence times, and feedstock composition ranges to prevent coking without requiring pre-treatment, thereby resolving the contradiction between reliability and complexity
2Manufacturing precision
If hydrotreating and fractionation are performed on plastic-derived liquid feedstock before steam cracking, then product quality and olefin content are controlled, but manufacturing costs increase
Solution Approach 1:
The patent removes the expensive hydrotreating and fractionation units from the process, directly feeding plastic-derived liquid feedstock into steam cracking. Product quality is maintained through direct control of cracking parameters and downstream separation, eliminating the need for costly pre-treatment while achieving the desired olefin content and product specifications
Solution Approach 2:
The invention adjusts cracking temperature, pressure, and residence time parameters to optimize product quality directly from the cracker. By controlling these parameters and the feedstock composition range, the process achieves the required manufacturing precision without the additional manufacturing cost of pre-treatment facilities
3Ease of manufacture
If plastic-derived liquid feedstock with higher boiling point and olefin content is used directly in steam cracking, then pre-treatment costs are reduced, but fouling and coking issues worsen
Solution Approach 1:
The patent converts the potentially harmful high boiling point and olefin content characteristics of plastic-derived feedstock into benefits. By using direct steam cracking with optimized parameters, the process effectively handles these feedstock properties, preventing coking through controlled thermal conditions while maintaining the economic advantage of eliminating pre-treatment steps
Solution Approach 2:
The invention changes the thermal processing parameters including temperature profiles, heating rates, and residence times to prevent coking and fouling. By carefully controlling these parameters during direct steam cracking, the process manages the harmful effects of high boiling point feedstock while maintaining cost-effectiveness
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 method allows for efficient conversion of plastic-derived feedstock into valuable products without pre-processing, reducing capital expenses and avoiding coking, while maintaining high yield and product quality.
Implementation Method 1
quenching the cracked product from a temperature of about 750° C. or greater to a temperature of about 350° C. or less with a quench oil
Implementation Method 2
steam cracking a plastic-derived liquid feedstock in a steam cracker to produce a cracked product
Data Source
AI summary
A method for steam cracking a plastic-derived liquid feedstock can comprise: steam cracking a plastic-derived liquid feedstock in a steam cracker to produce a cracked product, wherein the plastic-derived liquid feedstock has a final boiling point of about 550° C. or less and an olefin content of about 40 wt % or less; quenching the cracked product from a temperature of about 750° C. or greater to a temperature of about 350° C. or less with a quench oil; and wherein the method does not comprise hydrotreating and/or fractionating the plastic-derived liquid feedstock before steam cracking.