Gradient Depth Filter Structure for High-Flow Fine Particle Trapping
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Solution Overview
Problem
Conventional high-precision depth filters face challenges in handling fluids with wide particle distributions, leading to high filtration pressure, reduced productivity, and potential filter medium collapse due to wide particle distributions and high viscosity.
Innovation Solution
A depth filter design using mixed-fiber nonwoven fabric with a continuous fiber diameter and basis weight gradient, combined with a single-fiber nonwoven fabric, to maintain low filtration pressure and high precision, allowing for high flow rates and stable filtration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-precision filters are used to trap fine particles in fluid with wide particle distribution, then filtration precision is improved, but filtration pressure rises rapidly and productivity decreases
Solution Approach 1:
The filter is divided into multiple layers with different fiber diameters: a first layer with larger fiber diameter for coarse particle filtration and a second layer with smaller fiber diameter for fine particle filtration. This segmentation allows each layer to handle specific particle sizes, preventing rapid pressure rise while maintaining high filtration precision for fine particles.
Solution Approach 2:
Different regions of the filter have different fiber diameter characteristics tailored to local filtration needs. The first layer has larger fiber diameters optimized for coarse particle removal, while the second layer has smaller fiber diameters optimized for fine particle trapping. This local quality differentiation enables the filter to handle wide particle distributions efficiently without sacrificing productivity.
2Productivity
If high filtration pressure is applied to maintain high flow rate, then productivity is improved, but filter medium collapse and particle push-out occur
Solution Approach 1:
The filter structure is segmented into a first layer with larger fiber diameter providing mechanical strength and pressure resistance, and a second layer with smaller fiber diameter providing fine filtration. This segmentation allows the first layer to bear the filtration pressure and prevent medium collapse, while the second layer maintains fine particle trapping capability, enabling high flow rate operation without compromising reliability.
Solution Approach 2:
The filter uses a composite structure combining two different nonwoven fabric layers with distinct fiber diameter characteristics. The first layer (larger fibers) provides structural integrity and pressure resistance, while the second layer (smaller fibers) provides fine filtration. This composite material approach enables the filter to withstand high filtration pressures without collapse or particle push-out, maintaining both high flow rate and reliability.
3Measurement precision
If multi-layer depth filters with fiber diameter gradient are used, then fine particle trapping is improved, but pressure resistance performance decreases
Solution Approach 1:
The filter is segmented into two distinct layers: a first layer with larger fiber diameter optimized for mechanical strength and pressure resistance, and a second layer with smaller fiber diameter optimized for fine particle trapping. This segmentation ensures that the layer responsible for fine filtration (second layer) does not need to bear the full filtration pressure, as the first layer provides structural support. Consequently, fine particle trapping performance is improved without sacrificing pressure resistance.
Solution Approach 2:
Each layer is designed with local quality optimized for its specific function. The first layer has larger fiber diameters providing high mechanical strength and pressure resistance, while the second layer has smaller fiber diameters providing fine particle trapping capability. This local quality differentiation allows the second layer to focus on fine filtration without needing to compromise on pressure resistance, as the first layer handles the mechanical loading.
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 filter achieves high filtration precision and low pressure drop, preventing filter medium collapse and ensuring high productivity even under increased filtration pressure, making it suitable for fluids with wide particle distributions.
Implementation Method 1
melt-blown fiber B made of a thermoplastic resin B having a melting point lower than the thermoplastic resin A
Implementation Method 2
the fiber diameter is changed to become continuously finer from the pre-filtration layer to the precision filtration layer between the filter medium layers
Implementation Method 3
the depth filter is formed by winding a mixed-fiber nonwoven fabric composed of a melt-blown fiber A made of a thermoplastic resin A and a melt-blown fiber B made of a thermoplastic resin B
Data Source
AI summary
Provided is a depth filter that not only has excellent filtration precision even for a fluid having a wide particle distribution and exhibits excellent fine particle trapping performance, but also has high liquid permeability that allows filtration at a high flow rate while maintaining a low filtration pressure. This cylindrical depth filter comprises: a pre-filtration layer; and a precision filtration layer disposed on the downstream side of the pre-filtration layer in the filtration direction. The depth filter is formed by winding a mixed-fiber nonwoven fabric, which comprises a melt-blown fiber A and a melt-blown fiber B having a lower melting point than the same, and a single-fiber nonwoven fabric, which has an average fiber diameter of less than 1 µm but not less than 0.1 µm and a fiber diameter variation coefficient of 3.0 or less. The filter is provided with a gradient, in which the average fiber diameter of the mixed-fiber nonwoven fabric decreases from the pre-filtration layer toward the precision filtration layer. At least a portion of the single-fiber nonwoven fabric is wound so as to overlap with the mixed-fiber nonwoven fabric that constitutes the precision filter layer.