Prefractionation Column for Oligomerization Effluent Energy Reduction
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Solution Overview
Problem
The fractionation of oligomers to separate liquefied petroleum gas, gasoline, and middle distillates is an energy-intensive process, consuming more than 70% of the total energy in the processing unit, with high reboiling temperatures and limited thermal integration opportunities.
Innovation Solution
The integration of a prefractionation column reduces energy requirements by producing an overhead fraction containing LPG and light gasoline, and a bottom fraction containing heavy gasoline and middle distillates, which are then processed in subsequent columns to achieve efficient separation with reduced reboiling temperatures and thermal integration using available hot fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional fractionation section with two distillation columns (debutanizer and separator) is used, then the separation of LPG, gasoline, and middle distillate is achieved, but the energy consumption is very high (more than 70% of total processing energy)
Solution Approach 1:
The fractionation process is divided into three distinct distillation columns (deprefractionator, debutanizer, and separator) that operate in sequence. The deprefractionator performs preliminary separation to remove heavy components before the main fractionation steps, allowing the subsequent columns to operate more efficiently with reduced energy requirements while maintaining product separation quality.
Solution Approach 2:
The deprefractionator column performs preliminary fractionation of the oligomerization effluent before it enters the main debutanizer and separator columns. By removing heavy gasoline and middle distillate components in advance, the subsequent columns handle lighter loads with lower reboiling temperature requirements, significantly reducing total energy consumption while preserving separation effectiveness.
2Manufacturing precision
If high reboiling temperatures are used in the fractionation columns, then efficient separation of hydrocarbon components is achieved, but hot utility consumption increases significantly
Solution Approach 1:
The separation process is segmented across three columns with progressively lower operating temperatures. The deprefractionator handles the highest temperature separation of heavy components, the debutanizer operates at intermediate temperatures for LPG/gasoline separation, and the separator operates at the lowest temperatures for final gasoline/distillate separation. This segmentation allows each column to operate at optimized temperature levels, reducing cumulative hot utility consumption while maintaining separation efficiency.
Solution Approach 2:
The invention changes the operating temperature parameters of the fractionation columns by introducing the deprefractionator that operates at higher temperatures to remove heavy components first. This parameter change allows the subsequent columns to operate at lower temperatures, reducing the overall hot utility requirement while maintaining effective separation through the staged approach.
3Device complexity
If the fractionation process is simplified with fewer columns, then equipment complexity is reduced, but separation precision and product quality deteriorate
Solution Approach 1:
The fractionation train is segmented into three specialized columns, each handling a specific separation task. The deprefractionator removes heavy components, the debutanizer separates LPG and light gasoline, and the separator finishes the separation of gasoline and middle distillate. This segmentation provides superior separation precision compared to conventional two-column systems while the modular design allows for efficient operation.
Solution Approach 2:
The deprefractionator acts as an intermediary column between the oligomerization reactor and the conventional debutanizer/separator system. It performs the intermediate function of removing heavy components that would otherwise burden the main fractionation columns, enabling them to operate more efficiently and achieve better overall separation 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 significantly reduces hot utility consumption by at least 30% and facilitates thermal integration, maintaining product quality and quantities while optimizing energy use in the fractionation process.
Implementation Method 1
The effluent from the oligomerization section is sent to a prefractionator which leads to at least one overhead fraction containing a mixture of liquefied petroleum gas and light gasoline and a bottom fraction containing a mixture of heavy gasoline and middle distillate
Implementation Method 2
said overhead fraction being sent to a debutanizer which leads to at least one liquefied petroleum gas cut and a light gasoline cut
Implementation Method 3
said bottom fraction and at least part of said light gasoline cut being sent to a separator making it possible to obtain at least one gaseous fraction, a gasoline fraction and a diesel fraction
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a process for the oligomerization of light olefins in which the effluent from the oligomerization section is sent into a pre-fractionator which leads to at least a head fraction containing a mixture of liquefied petroleum gas and light gasoline and a bottom fraction containing a mixture of heavy gasoline and middle distillate, said head fraction being sent into a starter which leads to at least a liquefied petroleum gas cut and a light gasoline cut, said bottom fraction and at least a part of said light gasoline cut being sent into a separator enabling the production of at least a gaseous fraction, a gasoline fraction and a diesel fraction.