Guard Bed Separator for Waste Plastic Pyrolysis Oil Refining
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Solution Overview
Problem
The refining of waste plastic pyrolysis oil is hindered by the production of ammonium salt (NH4Cl) during the hydrotreating process, leading to reactor corrosion, differential pressure issues, and reduced process efficiency due to the reaction of hydrogen chloride and nitrogen compounds.
Innovation Solution
A method involving a guard bed for dechlorination and a main bed for denitrification, with a separator to remove hydrogen chloride before denitrification, minimizing the formation of ammonium salt by separating the dechlorination and denitrification reactions and controlling reaction temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If dechlorination and denitrification are performed simultaneously in a single reactor, then the refining process is simpler, but ammonium salt accumulates causing corrosion and process problems
Solution Approach 1:
The refining process is divided into two separate reactors: a guard bed reactor for dechlorination and a main bed reactor for denitrification. This segmentation prevents the simultaneous presence of HCl and nitrogen compounds in the same reactor, thereby eliminating ammonium salt formation while maintaining process simplicity through sequential treatment stages.
Solution Approach 2:
Dechlorination is performed as a preliminary step in the guard bed reactor before the feed enters the main bed reactor for denitrification. By removing chlorine in advance, the subsequent denitrification process occurs without HCl present, preventing ammonium salt accumulation and protecting the main bed reactor from corrosion.
2Reliability
If dechlorination and denitrification are performed in separate reactors, then ammonium salt production is minimized, but the apparatus complexity increases
Solution Approach 1:
The system uses two specialized reactors with distinct functions: the guard bed reactor contains a dechlorination catalyst and handles HCl removal, while the main bed reactor contains a denitrification catalyst and handles nitrogen compound removal. This functional segmentation optimizes each reactor's performance while preventing harmful interactions.
Solution Approach 2:
The guard bed reactor acts as an intermediary unit between the feed source and the main bed reactor. It processes the feed to remove chlorine and protects the main bed reactor from exposure to HCl, thereby preventing ammonium salt formation without requiring complex additional equipment.
3Productivity
If hydrogen chloride is not removed before denitrification, then the process is more straightforward, but corrosion and differential pressure issues occur
Solution Approach 1:
HCl removal is performed as a preliminary action in the guard bed reactor before the processed feed enters the main bed reactor. This preliminary dechlorination eliminates the corrosive HCl that would otherwise cause reactor corrosion and differential pressure issues during the subsequent denitrification process.
Solution Approach 2:
The harmful HCl produced during dechlorination is not allowed to accumulate but is instead converted into a protective measure. By removing HCl in the guard bed, the main bed reactor is protected from corrosion, and the HCl removal process itself becomes a beneficial protective function that enables efficient denitrification without harmful side effects.
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 prevents ammonium salt accumulation, reducing reactor corrosion, improving durability and process efficiency, and achieving a high-quality refined oil with low impurity content.
Implementation Method 1
a dechlorination reaction is performed under a dechlorination catalyst
Implementation Method 2
a denitrification reaction is performed under a denitrification catalyst
Implementation Method 3
a separator to which a fluid including hydrogen chloride discharged from the guard bed is introduced and in which the hydrogen chloride is removed from the fluid
Data Source
AI summary
Provided are an apparatus and a method for refining pyrolysis oil in which a dechlorination reaction is performed under a first hydrotreating catalyst. Hydrogen chloride as a by-product is removed, and then a denitrification reaction is performed under a second hydrotreating catalyst, thereby preventing production of an ammonium salt (NH4Cl), and providing refined oil. It is excellent in prevention of corrosion of a reactor, improvement of durability, occurrence of differential pressure, process efficiency, has very low contents of impurities such as chlorine, nitrogen, and metal and olefin, and has excellent quality.