Electrostatically Charged Filter Rod for Sorbent Particle Capture
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Solution Overview
Problem
Cigarette filter assemblies face challenges in reducing the breakthrough of sorbent particles, such as activated carbon, in the gas stream due to their entrainment in mainstream smoke, which affects filtration efficiency.
Innovation Solution
A filter assembly is created using a lofty porous network of charge retaining polymer fibers that are electrostatically charged, either randomly or axially oriented, to attract and mechanically trap sorbent particles, thereby reducing or eliminating particle breakthrough. This network is formed into a filter rod with a suitable pressure drop and is positioned downstream of the sorbent material to capture particles effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sorbent particles are used in the filter assembly, then filtration efficiency is improved, but particle breakthrough in the gas stream increases
Solution Approach 1:
The patent employs a porous network formed by charge-retaining polymer fibers that creates a three-dimensional electrostatic field throughout the filter assembly. This porous structure allows the gas stream to pass through while the electrostatically charged fibers capture sorbent particles, preventing their breakthrough into the mainstream smoke without compromising filtration efficiency
Solution Approach 2:
The patent replaces traditional mechanical filtration mechanisms with an electrostatic field-based system. Charge-retaining polymer fibers generate electrostatic forces that attract and capture sorbent particles, substituting the need for dense mechanical barriers that would otherwise cause particle breakthrough while maintaining filtration effectiveness
2Reliability
If a dense filter structure is used to capture particles, then particle capture efficiency is improved, but pressure drop increases
Solution Approach 1:
The porous network of charge-retaining polymer fibers provides a three-dimensional structure with controlled porosity that allows gas flow while maintaining particle capture efficiency. The electrostatic field extends throughout the porous volume, enabling effective particle capture without requiring a dense structure that would increase pressure drop
Solution Approach 2:
The patent changes the fundamental parameter of particle capture from mechanical interception to electrostatic attraction. This parameter change allows the filter to operate with a more open, porous structure that maintains lower pressure drop while achieving the same or better particle capture efficiency through electrostatic forces
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 electrostatically charged porous network effectively captures sorbent particles, reducing or eliminating their breakthrough in the smoke stream, enhancing filtration efficiency and maintaining a suitable pressure drop for effective smoking article filtration.
Implementation Method 1
The one or more fibers of charge retaining polymer are charged
Implementation Method 2
The electrostatically charged porous network effectively captures sorbent particles
Data Source
AI summary
A filter rod comprises a core of cellulose acetate fibers surrounded by a lofty porous network of charge retaining polymer fibers. The charge retaining fibers can be charged to attract and hold particles from such sources as particulate matter from sorbents (preventing break-through), and smoke constituents while having a suitable pressure drop.