1,3-Butadiene Purification via Selective Solvent Extraction
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Solution Overview
Problem
The isolation of pure 1,3-butadiene from crude C4 fractions is challenging due to the small differences in relative volatilities of components, leading to inefficient separation processes and significant losses of valuable product, particularly due to the formation of polymer deposits caused by molecular oxygen and the need for frequent purging, which results in downtime and product loss.
Innovation Solution
A process involving extractive distillation using a selective solvent, where the crude C4 fraction is pre-purified in a predistillation column, then contacted with the solvent in an extraction column, followed by stripping and further purification in a pure distillation column, with a consolidated purge stream managing oxygen levels and utilizing internal streams to minimize losses and polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional distillation is used to separate 1,3-butadiene from crude C4 fraction, then separation is achieved, but the process is inefficient due to small differences in relative volatilities of components
Solution Approach 1:
A selective solvent is introduced as an intermediary substance that preferentially absorbs acetylenic impurities from the 1,3-butadiene stream. This solvent acts as a mediator to remove harmful components without requiring complex distillation processes, thereby improving separation efficiency while reducing process complexity.
Solution Approach 2:
The invention changes the physical-chemical parameters of the separation process by using a selective solvent with specific absorption characteristics. This parameter change enables efficient removal of acetylenic impurities through absorption rather than relying solely on volatility differences, addressing the inefficiency of conventional distillation.
2Productivity
If molecular oxygen is present in the process, then oxidation reactions can occur, but polymer deposits are formed causing severe damage and frequent purges are needed
Solution Approach 1:
The selective solvent is used to extract and remove molecular oxygen from the process stream. By taking out the harmful oxygen component, the process prevents polymer deposit formation while maintaining operational continuity, eliminating the need for frequent purges.
Solution Approach 2:
The invention converts the harmful effect of molecular oxygen into a beneficial process feature by using the oxygen present in the feedstock to drive the absorption process. The oxygen is utilized to enhance the selective solvent's ability to remove acetylenic impurities, transforming a harmful factor into a useful element.
3Reliability
If frequent purges are performed to remove polymer deposits, then equipment damage is prevented, but downtime and product loss occur
Solution Approach 1:
The selective solvent performs preliminary removal of molecular oxygen and acetylenic impurities from the process stream before polymer deposits can form. This preliminary action prevents equipment damage in the first place, eliminating the need for subsequent purges and associated downtime.
Solution Approach 2:
The invention enables continuous operation by maintaining the removal of harmful components through the selective solvent system. The process achieves continuity of useful action by continuously preventing polymer formation rather than allowing deposits to build up and requiring intermittent purges.
4Manufacturing precision
If conventional purification methods are used, then 1,3-butadiene can be isolated, but significant losses of valuable product occur
Solution Approach 1:
The selective solvent serves as an intermediary that specifically targets and removes acetylenic impurities from the 1,3-butadiene stream. This selective removal approach achieves high product purity while minimizing product loss by avoiding the need for extensive purging operations that would waste valuable 1,3-butadiene.
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 process enhances the yield and purity of 1,3-butadiene, reduces downtime, and minimizes product loss by effectively managing oxygen levels and polymerization, allowing for longer operation with increased efficiency and flexibility.
Implementation Method 1
The gaseous C4 fraction is brought into contact with a selective solvent in at least one extraction column, giving an overhead fraction comprising butanes and butenes and a bottom fraction comprising 1,3-butadiene and selective solvent
Implementation Method 2
crude 1,3-butadiene is desorbed from the bottom fraction in at least one stripping column, with a stripped selective solvent being obtained
Implementation Method 3
the crude C4 fraction is introduced into a predistillation column, a low boiler fraction comprising C3-hydrocarbons is taken off as overhead stream
Implementation Method 4
at least part of the crude 1-3-butadiene is fed to a pure distillation column and a second high boiler fraction is separated off
Data Source
AI summary
Process for isolating pure 1,3-butadiene from a crude C4 fraction by extractive distillation using a selective solvent, wherein (a) the crude C4 fraction is introduced into a predistillation column, a first low boiler fraction comprising C3-hydrocarbons is taken off as overhead stream, a gaseous C4 fraction is taken off as side stream and a first high boiler fraction is taken off as bottom stream, (b) the gaseous C4 fraction is brought into contact with a selective solvent in at least one extraction column, giving an overhead fraction comprising butanes and butenes and a bottom fraction comprising 1,3-butadiene and selective solvent, (c) crude 1,3-butadiene is desorbed from the bottom fraction in at least one stripping column, with a stripped selective solvent being obtained and the stripped selective solvent being recirculated to the extraction column, and (d) at least part of the crude 1-3-butadiene is fed to a pure distillation column and a second high boiler fraction is separated off and a gaseous purge stream is taken off. Gaseous purge streams from the columns which are necessary in order to keep the concentration of molecular oxygen below a predetermined concentration limit are consolidated with output streams which are in any case provided for discharging other components in the process. The recirculation of the second high boiler fraction to a lower section of the predistillation column creates a further degree of freedom in operation of the pure distillation column.