Liquid-Liquid Extraction Backwash Column for Hydrocarbon Impurity Separation
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Solution Overview
Problem
Current processes for producing butadiene from ethanol face challenges in efficiently separating hydrocarbon impurities, particularly partially polar hydrocarbons, which leads to impurity accumulation and reduced butadiene selectivity, requiring additional purification steps that result in losses of ethanol and acetaldehyde.
Innovation Solution
A process involving liquid-liquid extraction and distillation, where a hydrocarbon impurity with a boiling point between 20°C and 100°C and a partition coefficient of 0.1 to 5 is partially extracted by recycling a cut containing the impurity back into the backwash column, allowing for efficient separation without significant loss of ethanol or acetaldehyde, using a system of lateral withdrawal and recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distillation columns are used to separate hydrocarbon impurities from ethanol and acetaldehyde, then impurity removal is achieved, but significant losses of ethanol and acetaldehyde occur
Solution Approach 1:
The patent applies liquid-liquid extraction using an organic solvent to selectively extract hydrocarbon impurities from the hydroalcoholic fraction. The extraction column separates impurities into an organic phase while ethanol and acetaldehyde remain in the aqueous phase, achieving impurity removal without the losses associated with conventional distillation.
Solution Approach 2:
An organic extraction solvent acts as an intermediary substance to facilitate the separation of hydrocarbon impurities from the hydroalcoholic mixture. The solvent selectively dissolves impurities while leaving ethanol and acetaldehyde in the aqueous phase, enabling clean separation without direct contact between impurities and product streams.
2Manufacturing precision
If additional purification steps are added to remove impurities, then butadiene selectivity improves, but process complexity and energy consumption increase
Solution Approach 1:
The patent combines the purification function with the existing distillation section by integrating a backwash column that performs both impurity removal and product recovery functions. This merged approach achieves high butadiene selectivity without adding separate, complex purification trains.
Solution Approach 2:
The extraction-backwash system serves multiple functions simultaneously: removing hydrocarbon impurities, recovering ethanol and acetaldehyde, and preparing the stream for butadiene production. This multi-functional approach reduces overall process complexity compared to dedicated single-function units.
3Productivity
If impurities are not removed efficiently, then ethanol and acetaldehyde can be recycled, but impurity accumulation reduces catalyst performance and butadiene yield
Solution Approach 1:
The extraction column performs preliminary impurity removal before the hydroalcoholic fraction enters the distillation and recycling sections. By removing impurities early in the process, the system enables high-rate recycling of ethanol and acetaldehyde without risking catalyst poisoning or deactivation from impurity accumulation.
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 effectively concentrates acetaldehyde and ethanol effluents, minimizing losses and energy consumption, while improving butadiene production yield by optimizing the recovery of ethanol and acetaldehyde, thus enhancing the overall butadiene production efficiency.
Implementation Method 1
a liquid-liquid extraction step comprising an extraction section comprising a washing column (L) and a back-washing column (CL)... The organic solvent used for this unit operation may contain saturated and/or unsaturated and/or aromatic hydrocarbons
Implementation Method 2
at least one acetaldehyde separation step comprising an acetaldehyde separation section, composed of at least one distillation column (D1)... and at least one ethanol separation step comprising an ethanol separation section, composed of at least one distillation column (D2)
Data Source
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AI summary
The invention relates to a method for treating, by liquid-liquid extraction and distillation, a liquid feedstock comprising at least ethanol, water, acetaldehyde and at least one hydrocarbon impurity having a boiling point between 20°C and 100°C at atmospheric pressure, or generating, with at least one of the compounds of the liquid feedstock and/or the organic extraction solvent and/or the aqueous backwashing solvent, an azeotrope with a boiling point between 20 and 100°C at atmospheric pressure, and a partition coefficient between 0.1 and 5 at any point in the backwashing column (CL) of the extraction section, the method comprising (a) a liquid-liquid extraction step comprising a washing column (L), a backwashing column (CL) and at least one injection (F2) of a cut removed in step b) which is located in the upper half of the backwashing column, (b) a distillation step comprising a step of separating the aldehyde comprising a distillation column (D1), an ethanol separation step comprising a distillation column (D2) and at least one side stream on the column (D1) or (D2) of a cut comprising at least one of the ethanol or acetaldehyde compounds and the hydrocarbon impurity, the method producing at least one aldehyde-rich effluent, one ethanol-rich effluent and one water-rich effluent.