Bubble Feed Membrane Distillation Carrier Gas Injection
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Solution Overview
Problem
Current membrane distillation technologies lack efficient methods for enhancing carrier gas throughput in the feed side of membrane distillation modules, which limits the performance and energy efficiency of processes like air gap, permeate gap, conductive gap, direct contact, vacuum, and sweeping gas membrane distillation configurations.
Innovation Solution
The development of membrane distillation modules that include a vessel with a hydrophobic membrane dividing a feed zone and a distillate zone, where a carrier gas is introduced into the feed zone to enhance vapor transfer across the membrane, allowing vapor to permeate and condense in the distillate zone, and optionally incorporating features like blower/pump connections, thermally conductive dividers, and condensers to optimize the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional membrane distillation configurations are used without carrier gas injection, then the system structure remains simple, but the permeate flux and productivity are limited
Solution Approach 1:
The patent applies pneumatic principles by injecting carrier gas through spargers into the feed stream to create bubbles. This pneumatic action enhances mass transfer and vapor generation, significantly increasing permeate flux while maintaining a relatively simple system structure. The carrier gas bubbles provide intense mixing and increase the interfacial area for vaporization.
Solution Approach 2:
The patent utilizes porous hydrophobic membranes as the core separation medium. The porous structure allows vapor to pass through while blocking liquid, enabling high permeate flux. The membrane's pore size and hydrophobicity are optimized to enhance vapor transfer efficiency without compromising structural simplicity.
2Productivity
If carrier gas is injected into the feed stream to enhance vapor production, then permeate productivity increases, but energy consumption increases
Solution Approach 1:
The patent optimizes several parameters to balance productivity and energy consumption: carrier gas flow rate, sparger configuration, bubble size distribution, and feed temperature. By carefully controlling these parameters, the system achieves high permeate productivity while minimizing the energy required for carrier gas compression and heating.
Solution Approach 2:
The system utilizes the heat already present in the feed stream (from solar thermal collectors or waste heat sources) to vaporize water into the carrier gas bubbles. This self-heating approach reduces the additional energy required for vapor generation, as the feed stream's thermal energy is harnessed to drive the mass transfer process.
3Productivity
If carrier gas throughput is increased to improve mass transfer, then vapor production increases, but the system complexity and operational complexity increase
Solution Approach 1:
The patent divides the carrier gas injection into multiple spargers distributed throughout the feed stream path. This segmentation allows for better control of bubble distribution and size, enhancing mass transfer efficiency. Each sparger can be independently controlled, simplifying the overall operation by enabling localized optimization without managing a single complex injection system.
Solution Approach 2:
The carrier gas acts as an intermediary medium that facilitates mass transfer between the heated feed stream and the permeate side. By introducing this intermediate phase, the system achieves enhanced vapor production while maintaining manageable operational complexity, as the carrier gas can be easily controlled through standard gas flow meters and regulators.
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 enhances permeate flux, reduces energy consumption, and improves the overall efficiency of membrane distillation by increasing turbulent dissipation in the feed liquid, allowing for two-way vapor production and improved mass transfer across the membrane, thereby increasing productivity and energy efficiency compared to conventional systems.
Implementation Method 1
a hydrophobic membrane dividing the internal cavity into a feed zone and a distillate zone, such that the feed zone and a distillate zone are accessible to each other within the internal cavity only via permeation across the membrane
Implementation Method 2
a hydrophobic membrane dividing the internal cavity
Implementation Method 3
enhances permeate flux, reduces energy consumption, and improves the overall efficiency of membrane distillation by increasing turbulent dissipation in the feed liquid
Implementation Method 4
allowing for two-way vapor production and improved mass transfer across the membrane
Implementation Method 5
the vapor condenses in the distillate zone in the form of a distillate
Implementation Method 6
incorporating features like blower/pump connections, thermally conductive dividers, and condensers to optimize the process
Data Source
AI summary
Devices and techniques may improve the permeate productivity in membrane distillation separation by modifying the feed and/or coolant sides of a membrane distillation module depending on the membrane distillation configuration. The bubbling of a carrier gas through the feed liquid in the feed liquid side of the module can increase the turbulent dissipation rate and/or enhance mass transfer across the membrane pores.