Membrane Distillation Flow Reversal for Scaling Mitigation

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Solution Overview

Problem

Existing methods for concentrating hypersaline streams, such as membrane distillation, face challenges with membrane scaling and fouling, which reduce process efficiency and require costly chemical treatments to mitigate.

Innovation Solution

Implementing a membrane distillation system with flow reversal and temperature gradient reversal modes to manage scaling and fouling, where the flow direction and temperature differences across the membrane are alternated to prevent scaling and maintain membrane integrity without chemical cleaning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If membrane distillation is used to concentrate hypersaline streams, then water flux and solute rejection are maintained, but membrane scaling and fouling occur reducing process efficiency

Engineering Contradiction:

Improvewater fluxVSAvoidmembrane scaling and fouling

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements periodic flow reversal where the feed and permeate streams alternate sides of the membrane at regular intervals. This periodic switching prevents salt accumulation on any single membrane surface, thereby mitigating scaling and fouling while maintaining continuous water flux and solute rejection performance

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies flow reversal by inverting the normal flow configuration, where feed and permeate streams switch sides periodically. This inversion prevents the formation of concentration polarization layers and salt deposits on the membrane surface, resolving the contradiction between maintaining high productivity and preventing reliability issues

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If chemical treatments are applied to mitigate scaling and fouling, then membrane performance is maintained, but operational costs increase

Engineering Contradiction:

Improvemembrane performanceVSAvoidoperational costs

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The flow reversal system enables self-cleaning of the membrane surface by periodically flushing accumulated salts off the membrane. The hydraulic action of alternating flows automatically removes deposits without requiring external chemical interventions, thereby maintaining membrane performance while eliminating additional operational costs

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent extracts the need for chemical treatments by using purely physical flow reversal mechanisms. The system achieves scaling and fouling mitigation through hydraulic action alone, removing the requirement for chemical additives and associated operational expenses

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If open evaporation ponds are used to concentrate saline water, then mineral harvesting is achieved, but land resources are limited and evaporation time is long

Engineering Contradiction:

Improvemineral separation rateVSAvoidnatural evaporation time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent replaces the slow natural evaporation process with a membrane distillation system driven by controlled temperature gradients. This substitution accelerates water removal and mineral concentration by using thermal energy to drive vapor transport through the membrane, dramatically reducing processing time while maintaining high mineral separation rates

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 extends membrane lifetime, reduces maintenance costs, and maintains high water flux and solute rejection, enhancing the sustainability and efficiency of the concentration process.

Implementation Method 1

The difference in partial vapor pressures of the two streams controls the mass transport of water vapors in membrane distillation

Methodology Applied

Scientific EffectVapor pressure gradient: Pressure Gradient

Implementation Method 2

water evaporates from a heated feed stream of high salinity, diffuses through the pores of the membrane

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 3

water evaporates from a heated feed stream of high salinity

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 4

condenses into a cooler distillate stream on the opposite side of the membrane

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentUS11339062B2Methods for sustainable membrane distillation concentration of hyper saline streams

Publication Date: 2022.05.24 COMPASS MINERALS OGDEN INC

AI summary

A novel method of producing concentrated streams or otherwise useful hypersaline brines from a source of non-potable or otherwise impaired water is provided. The method comprises feeding the source water into the feed side of a membrane distillation unit while simultaneously feeding a distillate stream through the receiving side of the distillation unit. The feed and receiving sides are separated by a hydrophobic, microporous membrane that allows water vapor to flux through the membrane to the receiving side. As the membrane becomes clogged with particulates, the unit can be subjected to stream flow reversal and/or temperature gradient reversal in order to remove those particulates and restore previous vapor flux levels, after which previous operations can be resumed.