Oligomerization Process with Shared Fractionation Column
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Solution Overview
Problem
Existing oligomerization processes for producing gasoline range products face challenges in managing high concentrations of isobutylene, which lead to excessive reaction temperatures and side reactions, degrading product quality, and require multiple separation columns for efficient separation of unreacted olefins from oligomers.
Innovation Solution
A process utilizing at least two oligomerization reactors with a shared fractionation column for product separation, where a side cut from the column provides sufficient isobutylene for conversion in a second reactor, and flash vessels are used for rough separations to recycle unreacted feed and recover oligomeric products, reducing trimer and tetramer production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple separation columns are used to separate unreacted olefins from oligomers, then separation efficiency is improved, but device complexity increases
Solution Approach 1:
The single fractionation column is designed to perform multiple functions: separating unreacted olefins from oligomers, providing side cuts for the second reactor, and enabling product recovery. This multi-functional design eliminates the need for multiple separate separation columns while maintaining separation efficiency.
Solution Approach 2:
The patent combines multiple separation functions into a single fractionation column. The column integrates the separation of light olefins from oligomers with the provision of side draws for feeding the second reactor, merging what would traditionally require multiple separate units into one integrated system.
2Productivity
If high concentrations of isobutylene are used in the feed, then productivity is improved, but reaction temperature increases excessively
Solution Approach 1:
The oligomerization process is divided into two separate reactors. The first reactor handles the initial conversion of isobutylene, and the second reactor processes the side cut stream. This segmentation distributes the heat of reaction across two separate units, preventing excessive temperature rise in a single reactor while maintaining high overall conversion.
Solution Approach 2:
The fractionation column acts as an intermediary between the two reactors by separating the effluent from the first reactor and providing a controlled side cut to the second reactor. This intermediary function allows for temperature and concentration control, managing the exothermic reaction heat effectively.
3Productivity
If high concentrations of isobutylene are oligomerized, then productivity is improved, but side reactions increase degrading product quality
Solution Approach 1:
The two-reactor system segments the oligomerization process to control product distribution. The first reactor operates at conditions optimized for initial conversion, while the second reactor processes a specific side cut composition. This segmentation prevents excessive side reactions (trimer and tetramer formation) that would occur in a single high-conversion reactor, thereby maintaining product quality.
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 achieves high overall isobutylene conversion with controlled reaction temperatures and improved product quality by leveraging a shared separation column and strategic recycling, while maintaining low trimer and tetramer production levels.
Implementation Method 1
Flash vessels can be used in an embodiment to make rough separations of oligomerization reactor effluent between liquid and vapor to recycle the vapor containing unreacted feed to the reactor and send the liquid containing oligomeric product to the butene column for product recovery
Implementation Method 2
Separation is conventionally performed in a distillation column typically following the oligomerization zone. The lighter components comprising primarily unreacted C4− olefins and compounds that were present in the feed stream exit from the overhead of the distillation column. The heavier components comprising C5+ olefins and primarily oligomers and compounds exit out the bottoms of the distillation column
Implementation Method 3
Processes for the oligomerization of light olefins to produce C8 olefin oligomers are known. Oligomerization processes have been long employed to produce high quality motor fuel from C4 olefins. Such oligomerization processes are also referred to as catalytic condensation and polymerization
Data Source
AI summary
In an oligomerization process comprising at least two oligomerization reactors, at least portions of product streams from two reactors are separated in the same separator vessel. In an embodiment, a liquid product stream from the first oligomerization reactor is fed to a fractionation column and a side cut from the fractionation column feeds the second oligomerization reactor.