Extractive Distillation Heat Integration for Butene Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for separating butenes from C4 hydrocarbon streams containing butanes are inefficient in terms of energy recovery and require complex systems, failing to provide a butane-containing product stream with significant butene content suitable for downstream processes like adiabatic oligomerization.
Innovation Solution
The process involves extractive distillation using a solvent like N-methyl-2-pyrrolidone (NMP), where the solvent's heat is integrated to preheat streams and evaporate the C4 hydrocarbon stream, allowing for efficient energy recovery and maintaining a butane-containing product stream with at least 5% butenes, enabling subsequent adiabatic oligomerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If extractive distillation with high solvent-to-feed ratio is used to achieve complete butene separation, then separation yield is improved, but energy consumption increases and system complexity increases
Solution Approach 1:
The patent changes the separation parameter from complete butene removal to partial butene retention (5-20% in butane stream), which reduces the solvent-to-feed ratio requirement and consequently lowers energy consumption for solvent regeneration while maintaining economic viability through downstream oligomerization
Solution Approach 2:
Instead of discarding all butenes in the butane stream, the patent recovers them through adiabatic oligomerization to convert them into valuable C8 olefins, transforming what would be waste into a profit center and justifying the retained butene content
2Manufacturing precision
If extractive distillation with high solvent-to-feed ratio is used to achieve complete butene separation, then separation yield is improved, but device complexity increases
Solution Approach 1:
The patent modifies the separation specification to allow 5-20% butene content in the butane product stream, which significantly reduces the required solvent-to-feed ratio and simplifies the extractive distillation column design, solvent recovery system, and associated equipment
3Loss of energy
If heat integration is implemented to recover energy from hot solvent, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple heat recovery functions into a single heat integration network where hot solvent from the desorber simultaneously heats the feed stream, preheats solvent for the absorber, and provides steam for the reboiler, maximizing energy recovery while minimizing the number of separate heat exchangers and auxiliary systems
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 method achieves simple and efficient energy recovery, allowing significant butene retention in the butane-containing product stream, which is essential for producing valuable C8 olefins through adiabatic oligomerization, while simplifying the system technology.
Implementation Method 1
In an extractive distillation column, the absorber, the butenes are preferentially dissolved in the solvent
Implementation Method 2
the laden solvent is then freed of the butenes in a stripping column, the desorber, at elevated temperature
Implementation Method 3
the heat of the solvent, preferably of the NMP, removed as the bottom stream of the desorber is used for heat integration, in which the heat of the solvent, preferably of the NMP, is used in at least one heat exchanger for preheating the loaded solvent
Implementation Method 4
At least partial evaporation of the liquid C4 hydrocarbon stream in a feed evaporator
Implementation Method 5
the butane-enriched stream is fed to an adiabatic oligomerization in order to oligomerize the butenes present in the stream
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a method for separating butenes from C4 hydrocarbon streams containing butanes as well as butenes by means of extractive distillation with a suitable solvent, and a subsequent adiabatic oligomerisation. The method according to the invention is characterised by heat integration which makes it possible to use the heat of the solvent in order to heat and/or at least partly evaporate various streams.