Nanoporous Macrocycle Membranes for Natural Gas Pretreatment
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Solution Overview
Problem
Current membrane-based gas separation systems for natural gas upgrading require costly and space-consuming pretreatment systems to prevent membrane performance deterioration due to heavy hydrocarbon condensation, which increases the overall cost and footprint, especially in offshore applications.
Innovation Solution
Development of nanoporous macrocycle-containing cross-linked polymeric membranes using diisocyanate-terminated polyethers or polyesters crosslinked with α-, β-, and γ-cyclodextrins, which selectively permeate condensable hydrocarbons and reject methane, reducing the need for pretreatment systems by improving permeance and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pretreatment system is used to remove heavy hydrocarbons and control dew point, then membrane performance is maintained, but system cost increases by 10-40%
Solution Approach 1:
The patent employs a porous polymer membrane with specific pore size distribution (0.003-0.1 micrometers) that enables selective permeation of heavy hydrocarbons while rejecting methane and ethane. The porous structure provides high surface area and controlled transport pathways, allowing the membrane to perform separation functions that previously required complex pretreatment systems.
Solution Approach 2:
The membrane comprises a composite structure combining a porous polymer matrix with hydrophobic coating layers or surfactant modifications. This composite approach creates selective barriers that enhance heavy hydrocarbon permeation while maintaining mechanical integrity and chemical resistance, eliminating the need for separate pretreatment equipment.
2Reliability
If a pretreatment system is used to remove heavy hydrocarbons, then dew point control is achieved, but system footprint increases by 10-50%
Solution Approach 1:
The porous membrane structure provides high separation efficiency in a thin profile (1-50 micrometers), achieving dew point control without requiring the bulk volume of traditional pretreatment vessels. The porous architecture enables rapid mass transfer across a compact area, significantly reducing the footprint required for effective heavy hydrocarbon removal.
Solution Approach 2:
The membrane is configured as a thin-film structure that can be rolled or folded into compact modules, allowing high separation capacity in a minimal space. The thin-film design provides large active separation area per unit volume, enabling effective dew point control in offshore applications where space is constrained.
3Ease of manufacture
If conventional polymeric membranes are used, then manufacturing is simple, but selectivity and permeance for heavy hydrocarbons are insufficient
Solution Approach 1:
The membrane utilizes a controlled porous structure with specific pore size distribution achieved through phase inversion or foam stabilization techniques during manufacturing. This porous architecture provides inherent selectivity based on molecular size and condensation behavior, enhancing heavy hydrocarbon permeation without complex assembly steps.
Solution Approach 2:
The membrane performance is optimized by controlling manufacturing parameters such as polymer concentration, crosslinking degree, and pore-forming agent content. These parameter adjustments during fabrication create the desired pore size distribution and hydrophobicity, achieving high selectivity and permeance for heavy hydrocarbons while maintaining manufacturing feasibility.
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
The new membrane system effectively controls dew point and reduces costs and footprint by eliminating the need for high-cost pretreatment systems, while maintaining high selectivity and permeance for condensable vapors, thus enhancing natural gas upgrading efficiency and reliability.
Implementation Method 1
Rubbery polymeric membranes that can selectively and efficiently permeate heavy hydrocarbons and other contaminants such as CO2, H2S, and water vapor
Implementation Method 2
The major reason for the loss of membrane performance is heavy hydrocarbon liquid condensation on the membrane surface
Data Source
AI summary
The present invention involves a type of nanoporous macrocycle-containing cross-linked polymeric membrane, a method of making the membrane, and the use of such a novel membrane system for natural gas liquids (NGL) recovery, fuel gas conditioning, natural gas pre-treatment, sulfur removal from fluidized catalytic cracking (FCC) and other naphtha streams, as well as aromatic separations such as aromatic/paraffin separation and xylene separation. The nanoporous macrocycle-containing cross-linked polymeric membrane is prepared from a diisocyanate-terminated polyether or a diisocyanate-terminated polyester, that is crosslinked with a nanoporous macrocycle comprising hydroxyl functional groups such as α-, β-, and γ-cyclodextrins.