Perfluorosulfonated Ionomer Membrane for Hydrocarbon Isomerization
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Solution Overview
Problem
Current hydrocarbon isomerization processes face challenges with catalyst poisoning due to water and oxygenates, leading to increased maintenance and operating costs, as well as the corrosive nature of hydrochloric acid in off-gas streams, which complicates recycling and reuse of hydrogen and chloriding agents.
Innovation Solution
The implementation of a perfluorosulfonated ionomer membrane in off-gas and make-up hydrogen dryers to separate and recycle hydrogen, reducing the need for make-up hydrogen and chloriding agents by removing water from off-gas streams, thereby extending catalyst life and reducing maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If molecular sieve dryers are used to remove water from hydrogen and hydrocarbon feed streams, then water content is reduced and catalyst life is extended, but maintenance costs and capital costs increase due to frequent regeneration and replacement
Solution Approach 1:
The patent changes the drying mechanism from adsorption (molecular sieves) to membrane separation. The membrane dryer uses a hydrophobic porous membrane that selectively transports water vapor from the gas stream, eliminating the need for frequent regeneration and replacement associated with molecular sieves, thereby reducing maintenance costs while extending catalyst life.
Solution Approach 2:
The patent replaces the mechanical adsorption system (molecular sieves requiring regeneration cycles) with a membrane separation system. The membrane dryer operates continuously without regeneration, substituting the periodic mechanical regeneration process with a continuous passive separation process, reducing both maintenance and operational complexity.
2Reliability
If dual molecular sieve dryers are used to remove entrained water, then water removal is effective, but capital costs increase to provide duplicate equipment for maintenance
Solution Approach 1:
The patent replaces the dual molecular sieve dryer system with a single membrane dryer. The membrane technology provides continuous operation without regeneration shutdowns, eliminating the need for duplicate equipment. One membrane dryer can maintain continuous water removal while another would not be needed for backup, reducing device complexity and capital costs.
Solution Approach 2:
The membrane dryer enables continuous water removal without the periodic shutdowns required for molecular sieve regeneration. This continuous operation provides reliable water removal with a single unit, eliminating the need for duplicate equipment to maintain continuity during maintenance operations.
3Loss of substance
If hydrogen is recycled from the caustic scrubber off gas, then hydrogen reuse reduces make-up hydrogen requirements, but water in the off gas makes re-use impractical
Solution Approach 1:
The membrane dryer extracts water vapor from the hydrogen-containing off gas stream. The hydrophobic porous membrane selectively transports water molecules from the gas phase, separating water from hydrogen and other non-polar molecules. This extraction removes the harmful water content while preserving the hydrogen for recycling.
Solution Approach 2:
The hydrophobic porous membrane acts as an intermediary that selectively facilitates water vapor transport while blocking other gas components. The membrane's unique properties allow it to mediate the separation between water and hydrogen, enabling hydrogen recycling by removing only the water that would otherwise prevent reuse.
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 solution effectively recycles hydrogen and reduces the need for make-up hydrogen and chloriding agents, minimizing maintenance and operating costs while enhancing the efficiency of hydrocarbon isomerization processes by extending catalyst life and improving the handling of corrosive off-gas streams.
Implementation Method 1
The off gas dryer includes an off gas dryer membrane separating the off gas recycle stream from an off gas purge stream. The off dryer membrane includes a perfluorosulfonated ionomer.
Implementation Method 2
The make-up hydrogen dryer includes a make-up hydrogen membrane separating the raw make-up hydrogen stream from a make-up hydrogen purge stream, and the make-up hydrogen membrane includes a perfluorosulfonated ionomer.
Data Source
AI summary
Methods and apparatuses are provided for isomerizing a hydrocarbon stream. The method includes isomerizing a hydrocarbon stream in a reactor to produce an intermediate isomerized stream. The intermediate isomerized stream is fractionated to produce an off gas stream and a heavy isomerized stream, where the off gas stream includes an off gas recycle stream. The off gas recycle stream is dried in an off gas dryer to produce a hydrogen recycle stream, where the off gas drier includes an off gas dryer membrane separating the off gas recycle stream from an off gas purge stream. The off dryer membrane includes a perfluorosulfonated ionomer. The hydrogen recycle stream is then fed into the reactor.