Autothermal Reactor for Olefin Production from Waste Plastics
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Solution Overview
Problem
Conventional steam cracking processes for producing olefins from hydrocarbons are energy-intensive, produce significant carbon dioxide and NOx emissions, have low tolerance for contaminants, and require costly pre-treatment and carbon capture processes.
Innovation Solution
A process involving pyrolytic cracking of hydrocarbons in an autothermal reactor, where an oxygen-containing stream and a hydrogen and/or methane-containing stream are pre-heated and fed into a burner to generate high-temperature steam, which is then mixed with a pre-heated waste plastics pyrolysis oil feed stream in a mixing and cracking zone to produce olefins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional steam cracking is used to produce olefins from hydrocarbons, then olefin production is achieved, but large amounts of carbon dioxide are produced
Solution Approach 1:
The invention converts the harmful effect of carbon dioxide into a beneficial outcome by using it as a diluent gas in the cracking reactor. The CO2 that would normally be emitted is instead fed into the reactor where it serves to dilute the hydrocarbon feedstock and control the cracking reaction, thereby reducing the need for external carbon capture while maintaining olefin production efficiency
Solution Approach 2:
The invention recovers carbon dioxide from the combustion flue gas and reuses it within the cracking process. Instead of discarding CO2 through emission or expensive capture systems, it is recovered and fed into the reactor as a process gas, transforming a waste product into a useful component of the cracking environment
2Temperature
If fuel gas combustion is used to provide heat for pyrolytic cracking, then cracking temperature is achieved, but nitrogen oxide (NOx) is produced
Solution Approach 1:
The invention converts the harmful NOx produced during fuel combustion into a useful diluent gas for the cracking reaction. The flue gas containing NOx is fed into the cracking reactor where it serves to dilute the hydrocarbon feed and control reaction conditions, thereby transforming a pollutant into a process-beneficial gas
Solution Approach 2:
The invention recovers nitrogen oxide from the combustion flue gas and reuses it within the cracking process. Instead of discarding NOx through expensive DeNOx systems, it is recovered and fed into the reactor, eliminating the need for additional emission treatment equipment
3Productivity
If conventional steam cracker furnaces are used, then olefin production is achieved, but coke formation on tubes requires regular shutdowns for decoking
Solution Approach 1:
The invention extracts the heat source from the external furnace environment and places it inside the cracking reactor itself. By using an internal combustion chamber where fuel burns directly in the reactor, the heat is generated where it is needed, eliminating the external tubes and coils that are susceptible to coke formation and requiring shutdowns for maintenance
4Productivity
If waste plastics pyrolysis oil is used as feedstock, then olefin production from waste is achieved, but decontamination is required which costs money and reduces feedstock yield
Solution Approach 1:
The invention changes the operational parameters of the cracking reactor to accommodate contaminated feedstock. By adjusting temperature profiles, residence times, and using an autothermal design with internal combustion, the reactor can process waste plastics pyrolysis oil with high contaminant levels without requiring expensive pre-treatment, thereby minimizing feedstock loss while maintaining olefin production
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 reduces or avoids carbon dioxide and NOx production, has a high tolerance for contaminants, integrates well with waste plastics pyrolysis oil synthesis, minimizes coke formation, and achieves higher selectivities and yields for olefins compared to conventional steam cracking.
Implementation Method 1
feeding the pre-heated oxygen containing stream and the pre-heated hydrogen and/or methane containing stream into a burner of the autothermal reactor; generating steam in a combustion zone of the autothermal reactor
Implementation Method 2
pyrolytically cracking the hydrocarbons to provide an effluent containing olefins
Data Source
AI summary
The invention relates to a process for producing olefins from a waste plastics pyrolysis oil feed stream containing hydrocarbons. An oxygen containing stream and a hydrogen and/or methane containing stream are pre-heated outside a autothermal reactor in a burner of the autothermal reactor. Steam is generated in a combustion zone of the autothermal reactor. A waste plastics pyrolysis oil feed stream is pre-heated outside the autothermal reactor and then fed into the autothermal reactor. The steam generated in the combustion zone mixes with the pre-heated feed stream in a mixing and cracking zone of the autothermal reactor. The steam and the pre-heated feed stream are fed into the mixing and cracking zone from substantially opposite directions. The hydrocarbons are pyrolytically cracked to provide an effluent containing olefins.