Melt-Blown Depth Filter Cartridge with Concentric Zones
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Solution Overview
Problem
Conventional depth filter cartridges with diameters greater than 3 inches typically use pleated surface filters due to the limited surface area of depth filters, resulting in high clean water pressure drops and limited dirt holding capacity, which restricts their effectiveness in large-scale filtration applications.
Innovation Solution
A tubular depth filter element with three or more concentric zones made of essentially continuous melt blown filaments, where outer zone filaments overlap significantly with inner zones, and additional filaments traverse through all zones to enhance mechanical strength and filtration efficiency, allowing for larger diameters with low clean water pressure drops and increased dirt holding capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional depth filter cartridges use pleated surface filters to increase surface area, then filtration surface area is improved, but clean water pressure drop increases and dirt holding capacity is limited
Solution Approach 1:
The patent transitions from two-dimensional surface filtration to three-dimensional depth filtration. The filter media is configured with multiple concentric zones extending radially through the cartridge wall, creating a volumetric filtration path. This dimensional change allows water to be filtered through the entire volume of the cartridge wall rather than just across a surface, increasing dirt holding capacity while maintaining low pressure drop.
Solution Approach 2:
The patent employs porous melt-blown polymer filaments arranged in concentric zones with varying pore sizes. The outer zones have larger pores for preliminary filtration, while inner zones have smaller pores for fine filtration. This porous structure with gradient pore sizes provides high filtration efficiency and large dirt holding capacity without creating excessive resistance to water flow.
2Quantity of substance
If depth filter cartridges increase thickness to improve dirt holding capacity, then filtration capacity is improved, but mechanical strength and compression resistance decrease
Solution Approach 1:
The patent uses composite construction with multiple concentric zones of melt-blown filaments having different properties. Each zone is composed of filaments with specific diameter, density, and pore size characteristics. The outer zones use coarser filaments for structural support and preliminary filtration, while inner zones use finer filaments for high-efficiency filtration. This composite zoned structure provides both high dirt holding capacity and mechanical strength.
Solution Approach 2:
The patent applies local quality by varying the filament properties in different radial zones. The outer zones have larger filament diameters and higher density for mechanical strength and structural support, while inner zones have smaller filament diameters and optimized pore structures for fine particle filtration. This localized optimization of material properties throughout the cartridge wall provides both high dirt holding capacity and adequate mechanical strength.
3Ease of manufacture
If depth filter cartridges use uniform filament structure, then manufacturing is simplified, but filtration efficiency for different particle sizes decreases
Solution Approach 1:
The patent segments the filter media into multiple concentric zones, each with uniform filament structure optimized for specific filtration functions. The outer zones are manufactured with coarser filaments for preliminary filtration, while inner zones use finer filaments for high-efficiency filtration. Each zone maintains internal uniformity for ease of manufacturing, while the zoned structure provides differentiated filtration performance across the cartridge wall thickness.
Data Source
AI summary
A tubular depth filter element has three or more concentric zones. Each zone is made of an essentially continuous melt blown filament. The filament of an outer zone preferably has a larger diameter than the filaments of other zones. The outer zone overlaps with at least 85%, and preferably all, of another zone. Optionally, one or more additional filaments may traverse through all of zones. The depth filter element is made by spraying filaments onto a rotating mandrel to form a filament mass in contact with a conical press roller. The filaments are sprayed from three or more nozzles which are spaced apart along the length of the mandrel. One of the filaments is formed in a spray pattern that is angled towards an adjacent spray pattern so as to overlap with at least 50 or 85%, and preferably all, of the adjacent spray pattern.