Cross-Flow Filter Recirculation Using Retentate and Permeate Loops
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Solution Overview
Problem
Existing fluid filtration systems face challenges in maintaining optimal operating conditions for components like plasma filters, which differ from the system's preferred conditions, leading to reduced efficiency and increased maintenance due to solute buildup and fouling.
Innovation Solution
A recirculating fluid filtration system with a two-tiered pumping system, including a feed booster pump and a recirculation pump, along with a flow resistor, maintains desired pressure and flow rates, minimizing solute concentration and reducing fouling by circulating retentate with fresh fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If cross-flow filtration is used to wash away filtered particles and solutes, then filter operational time is increased, but solute buildup and fouling still occur reducing efficiency
Solution Approach 1:
The system dynamically adjusts operating parameters including flow rate, pressure, and recirculation ratio to optimize filtration performance. By changing these parameters over time and in response to system conditions, the system maintains high filtration efficiency while extending filter operational life through controlled solute management
Solution Approach 2:
The recirculation system continuously returns filtered retentate to the inlet, maintaining continuous washing action on the filter surface. This continuous circulation prevents solute buildup and fouling, allowing the filter to operate at optimal efficiency for extended periods without interruption or maintenance
2Productivity
If system pressure and flow rate are optimized for patient access, then system performance is improved, but plasma filter operating conditions differ from optimal
Solution Approach 1:
The system separates the functions of blood pumping and plasma filtration by introducing a dedicated recirculation loop with independent flow control. This segmentation allows the main pump to optimize for patient access requirements while the recirculation system independently optimizes plasma filter conditions, ensuring both system and filter operate at their respective optimal performance points
Solution Approach 2:
The system employs feedback control mechanisms that monitor filter operating conditions and system performance parameters. Based on this feedback, the recirculation flow rate and pressure are automatically adjusted to maintain optimal filter conditions even as system requirements change, ensuring consistent filter reliability and performance
3Reliability
If recirculation flow rate is increased to reduce solute concentration, then fouling is minimized, but power consumption increases
Solution Approach 1:
The recirculation system uses variable speed drives and dynamic flow control to adjust recirculation rate based on real-time filter conditions and contamination levels. Rather than operating at constant high flow, the system dynamically optimizes flow rate to maintain filter cleanliness while minimizing energy consumption during low-contamination periods
Solution Approach 2:
The system changes operating parameters including recirculation flow rate, pressure differential, and temperature to optimize the balance between fouling prevention and energy consumption. By adjusting these parameters based on filter loading and system requirements, the system achieves effective solute management with minimal power input
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 system optimizes filter performance by reducing power consumption, minimizing fouling, and extending the filter's lifespan through controlled fluid circulation and solute management.
Implementation Method 1
cross-flow filtration (also known as tangential flow filtration) is a type of filtration where the majority of the feed flow travels tangentially across the surface of the filter
Implementation Method 2
The 2nd pump supplies enough fluid flow to achieve a desired pressure in the filter given the flow resistances of the filter membrane and flow resistor
Implementation Method 3
circulating retentate with fresh fluid... minimizing solute concentration
Data Source
AI summary
A fluid filtration system comprising a cross-flow filter is arranged to permit a first pump to recirculate part of the retentate of the filter to the inlet of the cross-flow filter and a second pump to return part of the permeate to the inlet of the cross-flow filter. A third pump is configured supply source fluid to the inlet of the filter. The flow path between the second pump and the cross-flow filter inlet may include an adsorption filter that may selectively remove contaminants, toxins, or pathogens in the permeate. A controller may control the first, second and third pumps to provide predetermined flow ratios among the fluid flow paths of the system in order to achieve a desired filtration level. This system may be applicable to the removal of harmful substances from blood, by first separating the plasma from the blood and then removing harmful substances from the plasma.