Spiral Wound Membrane Module for High-Pressure Brine Concentration
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Solution Overview
Problem
Existing seawater reverse osmosis membranes struggle to achieve high concentration end points due to lower salt permeability and osmotic pressure buildup at high feed pressures, leading to insufficient permeate flow and membrane deformation.
Innovation Solution
A spiral wound membrane module using brackish water reverse osmosis membranes with enhanced water and salt permeability, combined with a permeate carrier having a specific design to manage osmotic pressure and prevent deformation, operates at high pressures to achieve higher concentration end points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If seawater reverse osmosis membranes are used to treat brackish water at high feed pressures, then the concentration end point can be increased, but the permeate flow becomes insufficient due to osmotic pressure buildup
Solution Approach 1:
The patent changes the operating parameters by using brackish water RO membranes instead of seawater RO membranes, which have different permeability characteristics. The brackish water membranes have higher salt permeability that allows them to maintain adequate permeate flow even at high concentration end points and high feed pressures (70-120 bar), resolving the contradiction between achieving high concentration and maintaining sufficient permeate flow
Solution Approach 2:
The patent employs a composite structure combining brackish water RO membranes with a specifically designed permeate carrier. The permeate carrier has narrow flow channels (215 micrometers or less at wide parts, 175 micrometers or less average) that work synergistically with the membrane properties to manage osmotic pressure and maintain flux at high operating pressures
2Quantity of substance
If high feed pressure is applied to increase concentration end point, then the concentration can reach above 130 g/L, but membrane deformation occurs
Solution Approach 1:
The patent uses a flexible permeate carrier structure with narrow flow channels that acts as a support for the membrane at high pressures. The permeate carrier's narrow channels (215 micrometers or less at wide parts) provide structural support that prevents membrane deformation while allowing the system to operate at high feed pressures (70-120 bar) to achieve concentration end points above 130 g/L
Solution Approach 2:
The permeate carrier is designed beforehand with narrow flow channels that pre-establish structural support to counteract the deformation forces that will occur during high-pressure operation. This preventive design allows the membrane to withstand high feed pressures without deforming, enabling high concentration end points to be achieved
3Productivity
If brackish water RO membranes are used instead of seawater membranes, then flux and concentration end points improve, but the membrane requires higher operating pressure
Solution Approach 1:
The patent changes the membrane type parameter from seawater RO to brackish water RO, which has different permeability characteristics. The brackish water membranes have higher salt permeability that enables them to achieve higher flux and concentration end points, though they do require higher operating pressures (70-120 bar compared to typical seawater RO operating pressures)
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 module achieves higher flux and concentration end points, exceeding 130 g/L, while managing osmotic pressure and membrane deformation, outperforming traditional seawater membranes.
Implementation Method 1
Reverse osmosis (RO) and nanofiltration (NF) membranes are made, for example, for seawater and brackish water desalination
Implementation Method 2
The membrane may have water permeability (A-Value) of at least 8*10−5 cm/s/bar at 25° C. The membrane may have salt diffusion rate, alternatively called salt permeability, (B-Value) of at least 0.5*10−5 cm/s at 25° C.
Implementation Method 3
the osmotic pressure when operating at high feed/retentate concentration, combined with the lower initial water permeability of seawater membranes, may result in insufficient permeate flow through a seawater membrane to reach high concentration end points
Data Source
AI summary
A spiral wound membrane module has a brackish water RO or NF membrane combined with a permeate carrier having a narrow spacing between membrane contacting elements. The membrane may have water permeability (A-Value) of at least 8*10−5 cm/s/bar at 25° C. The membrane may have salt diffusion rate (B-Value) of at least 0.5*10−5 cm/s at 25° C. The permeate carrier may have a density of 54 wales per inch or more of a gap between adjacent ribs of 215 um or less. The permeate carrier may have a channel cross-sectional area of 16*10−9 m2 or more. Water is fed to the module at a high feed pressure, for example a pressure of at least 50 bar, optionally up to 120 bar. Retentate may be discharged at a concentration of 100 g/L, 130 g/L, or 150 g/L or more.