Cross-Flow Cryogenic Slurry Filtration Using Stable Filter Media
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Solution Overview
Problem
Current separation technologies are ineffective, inefficient, and expensive for separating cryogenic solids from cryogenic liquids, particularly in cross-flow filtration, as existing filter media are not suitable for cryogenic temperatures and often require frequent cleaning or replacement due to solid deposition.
Innovation Solution
A cross-flow filtration method using a cryogenically-stable filter medium, such as sintered ceramics or polytetrafluoroethylene, that inhibits gas adsorption and solid deposition, and optimizes temperature-induced expansion and contraction to prevent damage and facilitate self-cleaning, allowing for the thickening of cryogenic slurries by tangentially passing the slurry across the filter medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional filter media are used for cryogenic slurry filtration, then the filtration process can be implemented, but the filter media collects solids over time requiring frequent cleaning or replacement
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical properties of the filter medium to be cryogenically stable. This includes selecting materials with appropriate thermal expansion coefficients, surface energies, and mechanical properties that prevent solid deposition and adsorption at cryogenic temperatures, thereby eliminating the need for frequent cleaning or replacement while maintaining continuous filtration productivity
Solution Approach 2:
The patent avoids the disposable approach by implementing a durable, long-lasting filter medium designed specifically for cryogenic service. Instead of using conventional media that require frequent replacement, the invention employs specialized materials that maintain their filtering capability indefinitely under cryogenic conditions, reducing both replacement costs and operational downtime
2Reliability
If filter media is selected to prevent solid adsorption, then solids can be filtered effectively, but the filter media must be tested extensively in laboratories to find the ideal material
Solution Approach 1:
The patent resolves the testing complexity by establishing specific material parameter criteria for cryogenic filter media. By defining required properties such as thermal stability, surface energy characteristics, and mechanical strength at cryogenic temperatures, the invention provides a systematic selection framework that reduces extensive laboratory testing to targeted evaluation of materials meeting these specified parameters
Solution Approach 2:
The patent employs composite materials that combine multiple properties in a single filter medium structure. These composites integrate materials with complementary characteristics - such as combining ceramic matrices with metallic or polymeric components - to achieve both chemical inertness and mechanical durability at cryogenic temperatures, thereby ensuring reliable performance without requiring complex multi-stage testing protocols
3Productivity
If existing filter media are used at cryogenic temperatures, then the filtration can proceed, but the filter media experiences temperature-change induced expansion and contraction causing damage
Solution Approach 1:
The patent addresses thermal stress damage by selecting filter media materials with thermal expansion coefficients matched to their support structures and housing. This parameter matching ensures that during cryogenic cycling, all components expand and contract uniformly, preventing differential stress, delamination, or structural failure that would compromise filter integrity and require shutdown for replacement
Solution Approach 2:
The patent explicitly accounts for thermal expansion effects by designing the filter assembly with expansion compensation mechanisms. This includes using materials with known, predictable expansion characteristics and incorporating design features such as flexible connections, expansion joints, or pre-stressed structures that accommodate dimensional changes during temperature cycling without causing damage to the filter medium or supporting infrastructure
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 method effectively separates cryogenic liquids from solids, preventing fouling and maintaining filter integrity, thereby enhancing the efficiency and durability of the separation process while reducing maintenance costs.
Implementation Method 1
Cross-flow filtration, sometimes referred to as tangential filtration, is a common method for removing solids in reverse osmosis, nanofiltration, ultrafiltration, and microfiltration
Implementation Method 2
temperature-change induced expansion and contraction of the filter medium is optimized
Implementation Method 3
adsorption of gases is inhibited
Data Source
AI summary
A method for thickening a cryogenic slurry is disclosed. The method comprises providing a cryogenic slurry flow path, a cryogenic liquid discharge path, and a filter medium between the cryogenic slurry flow path and the cryogenic liquid discharge path. The cryogenic slurry comprises a solid and a cryogenic liquid. The cryogenic slurry is fed into the cryogenic slurry flow path, generally tangential to the filter medium. This causes a portion of the cryogenic liquid to cross the filter medium into the cryogenic liquid discharge path as a cryogenic liquid discharge and the cryogenic slurry to thicken to produce a thickened slurry. The filter medium comprises a cryogenically-stable material such that adsorption of gases is inhibited, deposition of solids is prevented, and temperature-change induced expansion and contraction of the filter medium is optimized.