Solvent Clean-Up Zone with Co-Displacement Agent
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Solution Overview
Problem
Existing solvent regeneration techniques in extractive distillation and liquid-liquid extraction processes for aromatics recovery are inadequate for removing heavy hydrocarbons and polymeric sludge, leading to solvent contamination and equipment plugging due to the accumulation of high-boiling-point components.
Innovation Solution
A co-displacement agent is introduced to enhance the capability of a displacement agent in removing heavy hydrocarbons and polymeric materials from the solvent by using a solvent clean-up zone with a counter-current extraction system, where a light hydrocarbon-rich stream is used to 'squeeze out' heavies from the solvent phase into a hydrocarbon phase, reducing the need for high-temperature thermal regenerators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal solvent regenerator is used to remove heavy hydrocarbons, then heavy HCs with boiling points lower than solvent can be removed, but heavy polymeric materials with boiling points higher than solvent cannot be removed and accumulate in the solvent loop
Solution Approach 1:
The patent extracts polymeric materials from the solvent loop by introducing a displacement agent that selectively displaces polymeric materials from the solvent phase into a separate hydrocarbon phase. This allows polymeric materials to be removed from the solvent circulation system without requiring thermal degradation, thereby preventing equipment plugging and maintaining solvent purity.
Solution Approach 2:
The patent introduces a displacement agent as an intermediary substance that facilitates the removal of polymeric materials. The displacement agent interacts with both the solvent phase containing polymeric materials and the hydrocarbon phase, enabling the transfer and separation of polymeric materials from the solvent loop through counter-current extraction.
2Productivity
If thermal regenerator operates at high temperature to strip heavy hydrocarbons, then more heavy HCs can be removed from solvent, but solvent selectivity and solvency are significantly changed
Solution Approach 1:
The patent replaces the thermal field (high temperature) with a mass transfer field using a displacement agent. Instead of using thermal energy to strip heavy hydrocarbons, the system uses a displacement agent that selectively interacts with heavy hydrocarbons and polymeric materials, transferring them from the solvent phase to the hydrocarbon phase through counter-current extraction, thereby maintaining solvent properties while improving removal efficiency.
3Reliability
If solvent circulation time is increased to improve separation, then more heavy components can be removed, but polymeric materials accumulate and plug equipment
Solution Approach 1:
The patent continuously extracts polymeric materials from the solvent circulation system by introducing a displacement agent that selectively displaces polymeric materials into the hydrocarbon phase. This continuous removal prevents polymeric material accumulation and equipment plugging, allowing the solvent loop to operate indefinitely without maintenance interruptions.
Solution Approach 2:
The patent establishes a continuous counter-current extraction process where the displacement agent continuously contacts the solvent phase to displace polymeric materials into the hydrocarbon phase. This continuous action ensures that polymeric materials are constantly removed from the solvent loop, maintaining equipment operability and preventing accumulation over extended circulation times.
4Reliability
If water wash method is used to remove heavy hydrocarbons, then heavy HCs and PMs can be removed from solvent stream, but much water is required and process water distribution becomes difficult to balance
Solution Approach 1:
The patent extracts heavy hydrocarbons and polymeric materials from the solvent stream using a displacement agent that selectively displaces these components into the hydrocarbon phase. This method eliminates the need for large quantities of water, as the displacement agent directly interacts with the heavy components to transfer them from the solvent phase to the hydrocarbon phase through counter-current extraction.
Solution Approach 2:
The patent introduces a displacement agent as an intermediary that facilitates the removal of heavy hydrocarbons and polymeric materials without requiring water. The displacement agent serves as a mediator that transfers heavy components from the solvent phase to the hydrocarbon phase, eliminating the need for water-based washing and simplifying process water distribution.
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 effectively recovers a solvent substantially free of heavy hydrocarbons and polymeric sludge, reducing the loading requirements of thermal regenerators and maintaining solvent selectivity, thereby preventing equipment plugging and improving process operability.
Implementation Method 1
a light hydrocarbon-rich stream is used to 'squeeze out' heavies from the solvent phase into a hydrocarbon phase
Implementation Method 2
a co-displacement agent is used to enhance the capability of a primary displacement agent
Data Source
AI summary
Solvent regeneration to recover a polar hydrocarbon (HC) selective solvent substantially free of hydrocarbons (HCs) and other impurities from a solvent-rich stream containing selective solvent, heavy HCs, and polymeric materials (PMs) generated from reactions among thermally decomposed or oxidized solvent, heavy HCs, and additives is provided. A combination of displacement agent and associated co-displacement agent squeezes out the heavy HCs and PMs from the extractive solvent within a solvent clean-up zone. Simultaneously, a filter equipped with a magnetic field is positioned in a lean solvent circulation line to remove paramagnetic contaminants. The presence of the co-displacement agent significantly enhances the capability of the displacement agent in removing the heavy HCs and PMs from the extractive solvent. As a result, the solvent regeneration system operates under milder conditions and minimizes or eliminates the need for including a high temperature, energy intensive and difficult-to-operate thermal solvent regenerator.