Membrane Extraction Benzene Removal Hydrocarbon Streams
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Solution Overview
Problem
Current methods for removing benzene from hydrocarbon streams, particularly in catalytic reforming processes, are energy-intensive and costly, and existing separation techniques do not effectively manage benzene production in compliance with environmental regulations such as the EPA's benzene limit in gasoline.
Innovation Solution
The use of membrane separation to concentrate aromatics from hydrocarbon streams before extraction or hydrogen saturation, employing permselective membranes and selective aromatics extraction solvents to produce aromatics-rich streams, which are then processed to isolate benzene, toluene, and xylene efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional distillation is used to separate benzene from hydrocarbon streams, then benzene separation is achieved, but energy consumption is high and process cost is high
Solution Approach 1:
The membrane separation unit performs preliminary concentration of aromatics from the hydrocarbon stream before the extraction step. This pre-concentration reduces the load on the subsequent distillation/extraction process, allowing for lower energy consumption while achieving the required benzene separation purity.
Solution Approach 2:
A selective extraction solvent acts as an intermediary between the membrane-separated aromatic stream and the final benzene product. The solvent selectively extracts aromatics from the membrane permeate, facilitating separation with reduced energy requirements compared to direct distillation of the original hydrocarbon stream.
2Manufacturing precision
If traditional distillation is used to separate benzene from hydrocarbon streams, then benzene separation is achieved, but process cost is high
Solution Approach 1:
The membrane separation unit performs preliminary concentration of aromatics from the hydrocarbon stream before the extraction step. This pre-concentration reduces the load on the subsequent extraction process, allowing for lower operational costs while achieving the required benzene separation purity.
Solution Approach 2:
A selective extraction solvent acts as an intermediary between the membrane-separated aromatic stream and the final benzene product. The solvent selectively extracts aromatics from the membrane permeate, facilitating separation with reduced energy requirements and lower process costs compared to direct distillation of the original hydrocarbon stream.
3Use of energy by moving object
If membrane separation is used to concentrate aromatics before extraction, then energy consumption is reduced and process cost is reduced, but process complexity increases
Solution Approach 1:
The separation process is segmented into distinct functional units: a membrane separation unit for aromatic concentration and an extraction unit for benzene isolation. This segmentation allows each unit to be optimized for its specific function, reducing overall energy consumption while managing complexity through modular design.
Solution Approach 2:
The membrane separation unit serves multiple functions: it concentrates aromatics, reduces the load on the extraction unit, and can be configured to produce streams suitable for different downstream applications. This multi-functionality justifies the added complexity by providing benefits across multiple process objectives.
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 approach enhances the recovery of high-purity BTX compounds, reduces energy consumption, and meets stringent benzene limits in gasoline, offering a more economical and efficient method compared to traditional distillation-based processes.
Implementation Method 1
concentrating aromatics in the hydrocarbon stream by passing the hydrocarbon stream through a membrane unit having at least one membrane to produce a permeate stream and a retentate stream, wherein the permeate stream is aromatics rich relative to the hydrocarbon stream
Implementation Method 2
extracting aromatics after concentrating using a selective aromatics extraction solvent in an extraction unit to produce an extract stream, wherein the extract stream is aromatics rich relative to the permeate stream
Implementation Method 3
introducing hydrogen and the permeate stream into a benzene saturation unit; and saturating benzene with hydrogen to produce cyclohexane in the benzene saturation unit
Data Source
AI summary
A method of removing at least benzene from a hydrocarbon stream comprises concentrating aromatics in the hydrocarbon stream by passing the hydrocarbon stream through a membrane unit having at least one membrane to produce a permeate stream and a retentate stream, wherein the permeate stream is aromatics rich relative to the hydrocarbon stream; and extracting aromatics after concentrating using a selective aromatics extraction solvent in an extraction unit to produce an extract stream, wherein the extract stream is aromatics rich relative to the permeate stream.