Nanoweb Layer Composite Filter Media for Low Pressure Drop
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Solution Overview
Problem
Current filtration media, such as electret filters and membrane filters, face efficiency loss when exposed to moisture or oily particles, and require frequent replacement or cleaning due to high pressure drop and low dust capacity.
Innovation Solution
A composite filter media comprising a nanoweb layer as a depth filtration layer upstream of a microporous polymeric membrane layer, where the nanoweb is made of charged melt blown fibers with a basis weight of at least 2 gsm and the membrane is constructed from materials like ePTFE, enhancing filtration efficiency and reducing pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of non-woven polymeric web in the electret filter is increased to reduce efficiency loss from moisture or oily particles, then filtration reliability is improved, but pressure drop increases and weight and bulk are added
Solution Approach 1:
The filter media is divided into distinct functional layers: a prefiltration layer for capturing larger particles, a nanoweb layer for fine particle filtration with electrostatic enhancement, and a membrane layer for final particle removal. This segmentation allows each layer to perform its specific function optimally without requiring excessive material in any single layer, thereby maintaining low pressure drop while ensuring reliability.
Solution Approach 2:
The invention uses a composite structure combining different materials with complementary properties: the prefiltration layer uses coarser fibers for high capacity, the nanoweb layer uses electrostatically charged fibers for efficient fine particle capture, and the membrane layer provides stable filtration. This composite approach achieves both low pressure drop and high reliability by leveraging the strengths of each material type.
2Reliability
If membrane filter media is used to provide constant filtration efficiency, then filtration reliability is improved, but pressure drop increases and dust capacity decreases
Solution Approach 1:
The filter media is divided into distinct functional layers: a prefiltration layer for capturing larger particles, a nanoweb layer for fine particle filtration with electrostatic enhancement, and a membrane layer for final particle removal. This segmentation allows each layer to perform its specific function optimally without requiring excessive material in any single layer, thereby maintaining low pressure drop while ensuring reliability.
Solution Approach 2:
Different regions of the filter media have different filtration characteristics tailored to their specific functions. The prefiltration layer has higher porosity for capacity, the nanoweb layer has electrostatic properties for efficiency, and the membrane layer has uniform pores for consistency. This local differentiation allows the system to achieve both high dust capacity and constant efficiency.
3Productivity
If electrostatic filters are used to improve filtration efficiency, then particle collection efficiency is improved, but reliability decreases when exposed to moisture or oily particles
Solution Approach 1:
The filter media is divided into distinct functional layers: a prefiltration layer for capturing larger particles, a nanoweb layer for fine particle filtration with electrostatic enhancement, and a membrane layer for final particle removal. This segmentation allows each layer to perform its specific function optimally without requiring excessive material in any single layer, thereby maintaining low pressure drop while ensuring reliability.
Solution Approach 2:
The prefiltration layer acts as an intermediary that captures larger particles and oily aerosols before they reach the electrostatic nanoweb layer. This protective intermediary function prevents moisture and oily particles from deactivating the electrostatic charges in the nanoweb layer, thereby maintaining the reliability of the electrostatic filtration mechanism.
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 composite filter media provides superior longevity before cleaning or replacement, maintains low pressure drop, and improves dust holding capacity compared to conventional filters with similar efficiencies.
Implementation Method 1
The nanoweb layer comprises a charged melt blown web... Electrostatic filter materials, or electrets, have electrostatically enhanced fibers which enhance filter performance by attracting particles to the fibers, and retaining them.
Implementation Method 2
Surface filters, such as membranes, have gained popularity... Membranes have stable filtration efficiency because, unlike depth filtration media, a membrane filter's efficiency is not dependent upon the buildup of a cake of dust particles.
Implementation Method 3
The depth filtration layer upstream and in fluid contact with the membrane comprises a nanoweb layer and a prefiltration layer upstream of and in fluid communication with the nanoweb layer.
Data Source
AI summary
A filter media for filtering particulates from air or other gases contains a membrane, and a depth filtration layer upstream and in fluid contact with the membrane. The depth filtration layer contains a nanoweb layer and a prefiltration layer upstream of and in fluid communication with the nanoweb layer. The prefiltration layer may be a nonwoven, and in one embodiment, specifically a melt blown nonwoven which may also be charged.