Extractive Distillation Solvent Purification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Extractive distillation processes face inefficiencies due to the accumulation of heavy hydrocarbons and degradation products in the solvent loop, leading to sludge and plugging issues, which are costly to address and can degrade the solvent.
Innovation Solution
A method involving an extractive-distillation column with a solvent-rich stream purification process, using solid adsorbents in solvent-purification vessels to separate and recycle a hydrocarbon-free, polar-hydrocarbon-selective solvent by dividing the solvent into portions for adsorption and regeneration, effectively removing contaminants and heavy hydrocarbons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If extractive distillation is used to recover aromatics from hydrocarbon mixtures, then separation efficiency is improved, but heavy hydrocarbons accumulate in the solvent loop causing sludge and plugging
Solution Approach 1:
The patent extracts heavy hydrocarbons and degradation products from the solvent loop by introducing a stripping agent (steam or nitrogen) to the solvent recovery column. This removes the harmful accumulated components that cause sludge and plugging, while maintaining the closed-loop solvent circulation system for continuous aromatics recovery operation.
Solution Approach 2:
The patent changes operational parameters of the solvent recovery column, specifically increasing temperature and vacuum level, to enhance the removal of heavy hydrocarbons from the solvent. These parameter adjustments enable effective purification of the solvent without compromising the aromatics recovery process efficiency.
2Loss of substance
If temperature and vacuum level are increased to remove heavy hydrocarbons from solvent, then heavy hydrocarbon removal is improved, but solvent degradation occurs
Solution Approach 1:
The patent implements continuous solvent purification through the solvent recovery column operating in conjunction with the extractive distillation column. The solvent circulates continuously through the system, undergoing repeated purification cycles that gradually remove heavy hydrocarbons without requiring extreme temperature or vacuum conditions that would cause degradation.
Solution Approach 2:
The patent introduces a stripping agent (steam or nitrogen) as an intermediary substance in the solvent recovery column. This mediator facilitates the removal of heavy hydrocarbons from the solvent at milder conditions by creating a stripping effect, thereby avoiding direct thermal degradation of the solvent while achieving effective heavy hydrocarbon removal.
3Duration of action of stationary object
If solvent circulation in closed loop continues without purification, then process continuity is maintained, but heavy hydrocarbons accumulate causing operational inefficiency
Solution Approach 1:
The patent maintains continuous solvent circulation through the closed-loop system while simultaneously implementing continuous purification in the solvent recovery column. The solvent flows continuously from the extractive distillation column bottom, undergoes purification in the solvent recovery column, and returns to the extractive distillation column top, ensuring both operational continuity and progressive removal of heavy hydrocarbons.
Solution Approach 2:
The patent implements a feedback mechanism where the purified solvent from the solvent recovery column is fed back to the extractive distillation column. This closed-loop feedback ensures that the solvent quality is continuously maintained, preventing accumulation of heavy hydrocarbons that would otherwise reduce column efficiency and process productivity over time.
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 efficiently recovers pure aromatic hydrocarbons by removing heavy hydrocarbons and degradation products from the solvent loop, reducing sludge and plugging, and maintaining solvent integrity, thus enhancing process efficiency and reducing operational costs.
Implementation Method 1
introducing a portion of the solvent to a solvent-purification vessel containing a solid adsorbent to remove heavy hydrocarbons and products of degradation from the solvent
Implementation Method 2
As the solvent descends through the column, it preferentially extracts the polar components (aromatics) to form a rich solvent while the non-polar component vapor comprising non-polar components ascends to the top of the column
Implementation Method 3
Extractive distillation is a key separation method used in chemical processing, especially for the recovery of aromatics from hydrocarbon mixtures. A key aspect of extractive distillation is that a separating agent, a solvent with a high boiling point, is added to a component mixture for separation which increases relative volatility when the components have similar or close boiling points
Data Source
AI summary
The present invention relates to a process for recovering polar hydrocarbons from non-polar hydrocarbons, such as aromatics from non-aromatics, naphthenes from paraffins and isoparaffins, or olefins from paraffins and isoparaffins, in feed mixtures containing at least a measurable amount of heavier hydrocarbons. According to the invention, an improved extractive distillation (extractive-distillation) process is disclosed for recovering aromatic hydrocarbons including benzene, toluene, and xylenes from heavy (C9+) hydrocarbons. The invention also relates to an improved extractive-distillation process for recovering mainly benzene and toluene from the C6-C7 petroleum streams containing at least a measurable amount of C8+ hydrocarbons. This invention is further directed toward the regeneration and recovery of the extractive-distillation solvent utilized to recover and purify the aromatic hydrocarbons from the petroleum stream containing at least a measurable amount of hydrocarbons heavier than the intended product.