Multi-stage direct contact membrane distillation system and process
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Solution Overview
Problem
Existing membrane distillation systems are not commercially feasible due to inefficiencies in water permeate flux, high energy consumption, and membrane fouling issues.
Innovation Solution
A multi-stage direct contact membrane distillation (MS-DCMD) system with multiple modules, where a carrier gas is bubbled through feed chambers to enhance vapor transport, reduce fouling, and increase permeate flux, using membranes that allow vapor passage while blocking liquid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional membrane distillation systems are used, then the system structure is simple, but the water permeate flux is low and energy consumption is high
Solution Approach 1:
The system divides the single-stage membrane distillation process into multiple stages with separate feed chambers and permeate chambers. Each stage operates independently with its own membrane module, allowing optimized conditions for each stage and improving overall permeate flux while managing energy consumption more efficiently.
Solution Approach 2:
A carrier gas is introduced as an intermediary substance that facilitates vapor transport across the membrane. The carrier gas flows through the feed chamber, picks up vapor, and transports it to the permeate chamber, enhancing the mass transfer rate and improving water permeate flux without requiring excessive energy input.
2Reliability
If conventional membrane distillation systems are used, then the system is simple to operate, but membrane fouling occurs rapidly reducing efficiency
Solution Approach 1:
The system introduces dynamic flow conditions by introducing carrier gas at controlled flow rates and implementing multi-stage counter-current flow patterns. This dynamic operation creates shear forces that prevent fouling accumulation on membrane surfaces, maintaining stable permeate flux over time and improving membrane reliability.
Solution Approach 2:
The multi-stage configuration ensures continuous vapor transport and condensation throughout the system. The carrier gas continuously circulates through feed chambers, maintaining steady-state operation that prevents fouling buildup and sustains high permeate flux without interruption.
3Productivity
If single-stage membrane distillation is used, then the device complexity is low, but the productivity is insufficient for commercial feasibility
Solution Approach 1:
The system employs multiple membrane modules arranged in series, with each module representing a separate stage of vapor transport. This segmentation allows the system to handle larger volumes of feed solution and produce higher overall permeate flux, achieving commercial feasibility while maintaining manageable complexity through modular design.
Solution Approach 2:
Multiple membrane modules are combined into a single integrated system where feed from one stage becomes feed for the next stage. This merging of stages creates a multi-stage counter-current system that maximizes productivity by continuously processing concentrated feed solutions through multiple membrane barriers in sequence.
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 enhances productivity, reduces membrane fouling, and lowers energy demands by promoting turbulence and efficient mass and heat transfer, thereby increasing the efficiency and longevity of the membranes.
Implementation Method 1
a membrane separating the feed chamber from the cold chamber, wherein the membrane allows transportation of vapor from the feed chamber to the cold chamber while blocking liquid from moving from the feed chamber to the cold chamber
Implementation Method 2
A carrier gas is fed through the liquid in the feed chamber of each of the plurality of modules to form humidified carrier gas
Implementation Method 3
A purified liquid is condensed from the vapor in the cold chamber. The purified liquid is condensed from the humidified carrier gas
Implementation Method 4
cold water is circulated through the cold chamber
Data Source
AI summary
A multi-stage direct contact membrane distillation (MS-DCMD) system and a process for using the MS-DCMD are provide. The MS-DCMD includes a plurality of modules, wherein each module includes a feed chamber fluidically coupled to a feed line and a carrier gas line, wherein the feed line introduces a liquid feed into the feed chamber from a liquid feed tank, and wherein the carrier gas line introduces a carrier gas into the feed chamber. Each module includes a cold chamber fluidically coupled to a cold-water feed line and a cold-water return line, wherein cold water is circulated through the cold chamber. Each module further includes a membrane separating the feed chamber from the cold chamber, wherein the membrane allows transportation of vapor from the feed chamber to the cold chamber while blocking liquid from moving from the feed chamber to the cold chamber.