Aromatic Saturation in Pyrolysis Stream via Segmented Reactors
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Solution Overview
Problem
Steam cracking processes generate low-value by-products such as fuel oil from aromatics, which are not suitable for further processing into valuable olefins, and managing the exothermic heat generated during aromatic saturation is challenging.
Innovation Solution
The process splits the pyrolysis stream and hydrogen stream into multiple feed streams for dedicated saturation reactors, using a recycle stream to manage exotherms, converting aromatics into naphthenes that can be recycled and steam-cracked into valuable olefins, while maintaining the concentration of normal and iso-paraffins unchanged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aromatics are processed through steam cracking, then olefin production is achieved, but low-value fuel oil is generated as a by-product
Solution Approach 1:
The patent applies preliminary action by saturating aromatics to naphthenes before steam cracking. This pre-treatment converts aromatics into compounds that will crack into valuable olefins rather than forming fuel oil, thereby improving productivity while reducing energy loss to low-value by-products.
Solution Approach 2:
The patent changes the chemical parameter of the feedstock by converting aromatics to naphthenes through saturation. This parameter change transforms the cracking behavior of the material, enabling it to produce high-value olefins instead of low-value fuel oil during steam cracking.
2Productivity
If aromatics are saturated to naphthenes, then naphthene concentration increases for valuable olefin production, but exothermic heat is generated that requires management
Solution Approach 1:
The patent applies segmentation by dividing the aromatic saturation process into multiple reactors with inter-stage cooling. This breaks down the large exothermic heat release into manageable segments, allowing temperature control while achieving high naphthene concentration through complete saturation.
Solution Approach 2:
The patent uses an intermediary cooling system between saturation reactor stages. This intermediary removes excess heat generated during aromatic saturation, preventing temperature runaway while maintaining the productivity benefit of high naphthene concentration.
3Ease of manufacture
If pyrolysis stream is processed without aromatic saturation, then process simplicity is maintained, but aromatics yield low-value fuel oil
Solution Approach 1:
The patent introduces preliminary aromatic saturation before pyrolysis/steam cracking. While this adds process steps, it eliminates the problem of fuel oil formation, thereby improving energy efficiency and product value without significantly complicating the overall manufacturing process.
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 significantly increases the concentration of naphthenes and decreases aromatics, enhancing the value of steam cracking units by converting aromatics into valuable light olefins and effectively managing exothermic heat, as demonstrated by the simulation results showing a 99% reduction in total aromatics and a three-fold increase in naphthenes.
Implementation Method 1
saturation of a pyrolysis stream... converts aromatics into naphthenes
Implementation Method 2
managing the resulting exotherms... A recycle stream is also provided to manage the exotherm
Data Source
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AI summary
Saturation of a pyrolysis stream is achieved while managing exotherms. The pyrolysis stream is split into at least two feed streams for at least two saturation reactors. The process may split the hydrogen stream into at least two streams for the at least two saturation reactors. A recycle stream may also be provided to manage the exotherm. The feed may comprise at least 5 wt% aromatics.