BTX Recovery via Aprotic Solvent Absorption and Distillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for removing benzene, toluene, and xylene (BTX) from hydrocarbon gas streams are costly and inefficient, as they consume the extracted BTX, making it unavailable for recovery as a petrochemical feedstock or for commercial use.
Innovation Solution
Contacting a BTX-rich hydrocarbon gas stream with an aprotic solvent, such as sulfolane, in a gas-liquid contactor vessel to absorb BTX, followed by distillation to separate and recycle the BTX component, allowing for its recovery and reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed media adsorption is used to remove BTX from gas streams, then BTX removal is achieved, but the extracted BTX is consumed and cannot be recovered for commercial use
Solution Approach 1:
The patent implements a regenerative adsorption system where the adsorbent media is periodically regenerated through desorption using heated inert gas. This allows the captured BTX to be recovered in concentrated form while the media is restored for continued service, eliminating the consumption issue of conventional adsorption
Solution Approach 2:
The system operates in cyclic modes: adsorption phase where BTX is captured from the gas stream, and desorption/regeneration phase where heated inert gas releases the BTX from the media. This periodic operation enables continuous BTX recovery while maintaining removal effectiveness
2Duration of action of stationary object
If adsorption media is regenerated, then the media can continue operating, but the process requires taking media out of service or parallel circuits, reducing productivity
Solution Approach 1:
The system divides the adsorption process into multiple parallel beds that can operate independently. While one bed is in service treating gas streams, another bed undergoes regeneration. This segmentation allows continuous operation without interrupting gas treatment productivity
Solution Approach 2:
The regenerative system switches between adsorption and desorption phases in a periodic cycle, with multiple beds operating at different phases. This ensures that while one bed regenerates, others continue treating gas streams, maintaining continuous productivity
3Loss of substance
If regeneration steam is used to remove BTX from adsorption media, then BTX is recovered from the media, but a separate process is required to separate BTX from the regeneration fluid
Solution Approach 1:
The patent uses inert gas (such as nitrogen or carbon dioxide) instead of steam for desorption. This eliminates water contamination issues and allows direct condensation and separation of BTX from the inert carrier gas, simplifying the separation process and reducing device complexity
Solution Approach 2:
The system replaces complex steam separation processes with a simpler inert gas condensation system. The inert gas allows straightforward phase separation where BTX condenses out while the inert gas can be easily vented or recycled, reducing the need for complex separation equipment
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
Achieves high BTX removal efficiency, with approximately 99.6% and 99.1% removal of BTX and benzene respectively, enabling the BTX component to be recovered and utilized as a petrochemical feedstock or for commercial purposes.
Implementation Method 1
contacting a BTX-rich hydrocarbon gas feed stream with an aprotic solvent to produce a BTX-free gas and a BTX component
Implementation Method 2
followed by distillation to separate and recycle the BTX component
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
A recovery method and a system for delivering extracted benzene, toluene, and xylene from a hydrocarbon gas stream is provided. The method includes introducing a feed stream of a BTX-rich hydrocarbon gas into an absorber. The method further includes combining, in the absorber, the hydrocarbon gas with an aprotic solvent, such that the hydrocarbon gas and the aprotic solvent are thoroughly intermixed so that the BTX is absorbed into the aprotic solvent, resulting in the production of a BTX-rich solvent and a substantially BTX --free gas. The method further includes vaporizing, using a vaporizer, the BTX-rich solvent to produce a vaporized BTX-rich solvent, and separating, using a distiller, the BTX from the vaporized BTX-rich solvent for delivering the extracted BTX from the hydrocarbon gas. The separation of the BTX from the vaporized BTX-rich solvent also produces a BTX-lean solvent that is recycled back into the absorber as the aprotic solvent.