Cationic-Coated Nanofiltration Membrane for Low Sulfate Ion Concentration
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Solution Overview
Problem
Current systems for removing sulfate ions from water used in oil field injection struggle to achieve low enough concentrations, as they typically only lower sulfate ion concentrations to 40 to 100 ppm, which is not sufficient for all oil reservoirs, leading to salt deposition and hindering crude oil mining.
Innovation Solution
A sulfate ion removal system utilizing a nanofiltration membrane with a cationic coating, which filters water to effectively reduce sulfate ion concentrations by allowing seawater to pass through the membrane only once, achieving lower sulfate ion concentrations than existing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional nanofiltration membranes are used, then the system complexity is low, but the sulfate ion concentration cannot be reduced below 40 to 100 ppm
Solution Approach 1:
The patent applies local quality by modifying only the surface layer of the nanofiltration membrane with a cationic coating, while keeping the bulk membrane structure unchanged. This localized modification enhances sulfate ion rejection performance without requiring complete restructuring of the entire membrane system, thus achieving lower sulfate ion concentrations (below 40 ppm) while maintaining reasonable device complexity.
Solution Approach 2:
The patent employs composite materials by combining a conventional nanofiltration membrane base material with a cationic coating layer. This composite structure integrates the mechanical strength and basic filtration properties of the original membrane with the enhanced ion rejection capabilities of the cationic coating, achieving superior sulfate ion removal performance.
2Manufacturing precision
If multiple filtration stages are implemented to achieve lower sulfate ion concentrations, then the sulfate ion concentration is reduced, but the device complexity and processing cost increase
Solution Approach 1:
The patent applies parameter changes by modifying the surface charge characteristics of the nanofiltration membrane through cationic coating. This chemical parameter modification (adding positive charges to the membrane surface) fundamentally changes the interaction mechanism with sulfate ions, enabling single-stage filtration to achieve sulfate ion concentrations below 40 ppm, thereby avoiding the need for multiple filtration stages.
3Manufacturing precision
If a cationic coating is added to the nanofiltration membrane, then sulfate ion removal performance is enhanced, but the manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-coating the nanofiltration membrane with cationic materials during the membrane manufacturing process. This preliminary modification is integrated into the production workflow, allowing the cationic coating to be applied before the membrane is installed in the filtration system, thereby simplifying the overall implementation despite the added manufacturing step.
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 system successfully achieves even lower sulfate ion concentrations, preventing salt deposition and enabling long-term smooth crude oil mining by using a cationic-coated nanofiltration membrane, reducing costs by simplifying the system improvements over existing multi-step processing systems.
Implementation Method 1
a nanofiltration membrane that is provided in the flow passage, has a cationic coating constituting a surface of the membrane, and removes a sulfate ion contained in water to be treated by filtering the water to be treated
Implementation Method 2
the nanofiltration membrane has a cationic coating constituting a surface of the membrane, and removes a sulfate ion contained in the water to be treated by filtering the water to be treated
Data Source
AI summary
A sulfate ion removal system 100 includes: a flow passage 50; and a nanofiltration membrane 62 that is provided in the flow passage 50, has a cationic coating 40 constituting a surface of the membrane, and removes a sulfate ion contained in water to be treated by filtering the water to be treated. Treated water obtained by filtering, with the nanofiltration membrane 62, the water to be treated is, for example, injection water to be injected into an oil field.