Dividing Wall Column for Crude 1,3-Butadiene Separation
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Solution Overview
Problem
The separation of 1,3-butadiene from a C4 cut is complicated due to small differences in relative volatilities, requiring extractive distillation with a selective solvent, but existing processes are energy-intensive and prone to fouling, especially with the use of compressors for recycling solvent streams.
Innovation Solution
A process using a dividing wall column with controlled energy input and an acetylenes outgasser to remove C4 acetylenes, allowing for compressorless operation, reduced 1,3-butadiene loss, and improved solvent purification, which is then recycled for further distillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If extractive distillation with a selective solvent is used to separate 1,3-butadiene from C4 cut, then separation efficiency is improved, but energy consumption increases
Solution Approach 1:
The patent applies segmentation by dividing the distillation process into two functional sections within a single column: an extractive distillation section (upper part) for separation and a solvent regeneration section (lower part) for solvent purification. This segmentation allows both separation efficiency and energy efficiency to be achieved simultaneously by performing operations at appropriate locations in the column.
Solution Approach 2:
The patent merges the extractive distillation function and solvent regeneration function into a single integrated column system. By combining these two functions that were traditionally performed in separate units, the process reduces overall energy consumption while maintaining high separation efficiency for 1,3-butadiene.
2Reliability
If compressors are used for recycling solvent streams, then operational reliability is improved, but fouling increases
Solution Approach 1:
The patent replaces the mechanical compressor system with a thermal-driven vapor lift mechanism. Solvent vapor generated in the lower regeneration section naturally rises and transports liquid solvent upward without mechanical compression, eliminating the fouling associated with compressors while maintaining operational reliability through the inherent thermodynamic driving force.
3Productivity
If compressors are used for recycling solvent streams, then process continuity is improved, but energy consumption increases
Solution Approach 1:
The patent substitutes mechanical compression with a thermally-driven vapor transport mechanism. The solvent vapor generated during regeneration naturally rises and carries liquid solvent upward, providing continuous process operation without the high energy consumption of compressors.
Solution Approach 2:
The system uses its own internally generated solvent vapor to drive the solvent recycling process. The vapor produced during solvent regeneration in the lower column section automatically transports solvent upward without external energy input, making the system self-sufficient and energy-efficient.
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 reduces energy consumption, minimizes fouling, and enhances operational reliability by eliminating the need for compressors and achieving efficient separation of 1,3-butadiene with reduced 1,3-butadiene loss, resulting in a more economically viable and reliable process.
Implementation Method 1
controlling the energy input into the dividing wall column via the bottom evaporator
Implementation Method 2
in the acetylenes outgasser stripping out the C4 acetylenes overhead
Implementation Method 3
the separation is carried out by extractive distillation, i.e. a distillation with addition of an extractant which has a higher boiling point than the mixture to be separated
Implementation Method 4
addition of an extractant which has a higher boiling point than the mixture to be separated and which increases the differences in the relative volatilities of the components to be separated
Data Source
AI summary
1,3-butadiene is obtained by extractive distillation with a selective solvent from a C4 cut comprising C4 acetylenes as secondary components in a dividing wall column having a bottom evaporator, in which a dividing wall is disposed in the longitudinal direction of the column to form a first subregion, a second subregion and a lower combined column region. The column is disposed upstream of an extractive wash column. The energy input into the dividing wall column via the bottom evaporator is controlled in such a way that a bottom stream containing solvent, C4 acetylenes and 1,3-butadiene restricted such that the loss of 1,3-butadiene is economically acceptable, is drawn off and fed to an acetylenes outgasser where the C4 acetylenes are stripped out overhead and purified solvent is obtained as the bottom stream.