Microporous Membrane Capillary Condensation Hydrocarbon Separation
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Solution Overview
Problem
Existing membrane separation methods for hydrocarbon mixtures, such as those using zeolite membranes, suffer from low permeability due to small pore diameters, making them ineffective and uneconomical for industrial gas treatment, as they require cooling the entire gas volume and have limited selectivity.
Innovation Solution
The method employs microporous membranes with a uniform pore diameter of 5 to 250 nm, allowing for selective capillary condensation and increased permeability by cooling only the membrane and permeate, enabling efficient separation of low molecular weight hydrocarbons without deep cooling of the gas stream, using materials like anodic aluminum oxide and track-etched polymeric membranes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If zeolite membranes with small pore diameters are used for capillary condensation separation, then selectivity for heavy hydrocarbon separation is improved, but membrane permeability deteriorates to less than 1 m3/m2·atm·h
Solution Approach 1:
The patent changes the pore diameter parameter from the traditional small zeolite pores to microporous membrane pores with diameters of 5-250 nm, and controls the pore size distribution to be uniform within ±10%. This parameter change enables capillary condensation to occur at higher pressures while maintaining high permeability, resolving the contradiction between selectivity and productivity
Solution Approach 2:
The patent employs microporous membranes with controlled pore size distribution as the separation medium. These porous materials enable capillary condensation of heavy hydrocarbons while maintaining high gas permeability through the micropores, achieving both high selectivity and high productivity simultaneously
2Reliability
If the entire gas volume is cooled for separation, then separation efficiency is improved, but energy consumption deteriorates
Solution Approach 1:
The patent applies cooling only to the membrane module and permeate side rather than the entire gas volume. This localized cooling approach creates the necessary temperature gradient for capillary condensation in the membrane pores while minimizing energy consumption, resolving the contradiction between separation efficiency and energy use
3Productivity
If microporous membranes with larger pore diameters are used, then membrane permeability is improved, but capillary condensation selectivity deteriorates
Solution Approach 1:
The patent optimizes the pore diameter parameter to the specific range of 5-250 nm with uniform distribution (±10% variation). This precise parameter control enables the membrane to achieve high permeability while maintaining the capillary condensation mechanism for selective heavy hydrocarbon separation, resolving the contradiction between productivity and manufacturing precision
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 significantly enhances membrane permeability and selectivity, achieving separation factors greater than 60 for heavy hydrocarbons, reduces energy costs, and allows for effective drying of petroleum gases using a small membrane surface area, while maintaining high efficiency and selectivity in gas separation.
Implementation Method 1
The invention relates to a method of fractionating hydrocarbons based on the selective capillary condensation of the gases in the pores of microporous membranes
Implementation Method 2
Realization of the method of capillary gas condensation in channels of such membranes allows for achieving unique parameters of butane permeability
Data Source
AI summary
The invention relates to membrane gas separation, in particular to a method of fractionating mixtures of low molecular weight hydrocarbons based on the capillary condensation of the mixture components in the pores of microporous membranes having uniform porosity and a pore diameter of 5 to 250 nm, wherein, for capillary condensation, the temperature of the membrane and the pressure on the permeate side are kept below the temperature and the pressure of the feed mixture. The method provides significantly increasing membrane permeability with respect to condensable components, and also component separation factors, while also allowing to avoid deep cooling of the gas stream fed to a membrane module, and to carry out gas separation under insignificant cooling of the membrane on the permeate side (down to -50° C.). The invention provides for energy-efficient fractionation of hydrocarbon mixtures, including separation and drying of natural and associated petroleum gases.