Aromatic Hydrocarbon Recovery from Vent Gas via Selective Solvent Absorption
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Solution Overview
Problem
Current processes for recovering aromatic hydrocarbons from vapor streams are energy-intensive and inefficient, particularly for intermittent sources, leading to significant energy consumption and aromatic hydrocarbon waste as fuel gas.
Innovation Solution
A process utilizing an aromatic selective solvent, such as 1,1-dioxide tetrahydrothiofuran or tetrahydrothiophene 1,1-dioxide, to absorb aromatic hydrocarbons from vapor streams in an absorption zone, followed by separation into aromatic lean and solvent-rich streams, with the solvent stream being processed further to recover valuable aromatics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If pressure is increased or vent gas is compressed to recover aromatic hydrocarbons from continuous vapor streams, then aromatic hydrocarbon recovery is improved, but energy consumption increases
Solution Approach 1:
The patent extracts aromatic hydrocarbons from vapor streams using an aromatic-selective solvent in an absorption zone, separating the desired aromatics from the vapor phase without requiring compression or pressure increase. The solvent selectively absorbs aromatic components, allowing recovery at near-atmospheric conditions, thus avoiding the energy-intensive compression step while maintaining high recovery efficiency.
Solution Approach 2:
The patent introduces an aromatic-selective solvent as an intermediary substance that mediates between the vapor stream and the liquid phase. This solvent acts as a carrier that selectively transports aromatic hydrocarbons from the vapor phase to the liquid phase through absorption, enabling separation without mechanical compression and reducing energy consumption significantly.
2Loss of substance
If vent gas is compressed to highest off-gas system pressure for aromatic recovery, then aromatic hydrocarbon recovery is improved, but heat integration capability deteriorates
Solution Approach 1:
The patent extracts aromatic hydrocarbons through selective absorption in an absorption zone operating at near-atmospheric pressure, avoiding compression to highest off-gas system pressure. This extraction approach maintains the vapor stream's thermal characteristics, preserving heat integration capability with other process streams while achieving effective aromatic recovery.
Solution Approach 2:
The patent changes the operating pressure parameter from highest off-gas system pressure to near-atmospheric pressure in the absorption zone. This parameter change maintains the thermodynamic compatibility of the vapor stream with heat integration requirements while still achieving effective aromatic hydrocarbon recovery through the aromatic-selective solvent absorption process.
3Use of energy by moving object
If aromatic hydrocarbons are used as fuel gas instead of being recovered, then energy input is reduced, but economic value is lost
Solution Approach 1:
The patent extracts aromatic hydrocarbons from vapor streams using an aromatic-selective solvent before the vapor would be combusted as fuel gas. This extraction recovers valuable aromatic components (benzene, toluene, xylenes) that can be sold as chemical feedstocks, converting what would have been low-value fuel into high-value chemical products while requiring minimal additional energy input.
Solution Approach 2:
The patent changes the fate of aromatic hydrocarbons from combustion (energy input) to selective absorption and recovery (material valorization). By changing the process parameter from direct fuel combustion to solvent absorption followed by aromatic recovery, the system transforms low-value fuel gas into high-value chemical products, significantly increasing economic return with minimal energy penalty.
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 reduces energy consumption and allows for efficient recovery of aromatic hydrocarbons from both continuous and intermittent vapor streams, increasing the yield of valuable aromatics while minimizing energy losses.
Implementation Method 1
passing a solvent into the absorption zone, wherein the solvent is an aromatic selective solvent for absorbing aromatic hydrocarbons
Data Source
AI summary
Processes for the recovery of aromatic hydrocarbons from one or more vent gas streams associated with an aromatic complex. The vapor streams are passed to an absorption zone in which an aromatic-selective solvent absorbs the aromatics. The aromatic-selective solvent can be processed along with other solvent extraction streams within the aromatic complex. The absorption zone may be a portion of an existing vessel or column, such as an extractive distillation column or a stabilizer.