Liquid Filtration Device with Recirculating Precoat Zone
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Solution Overview
Problem
Existing filter systems for liquids in machine tools, such as cooling lubricant emulsions, face challenges in maintaining consistently high-quality filtrate due to fluctuations in dirt particle content caused by the buildup and transport of filter cakes, which can lead to increased pressure drops and potential damage to downstream units.
Innovation Solution
A filter system with a separate dirt tank and collection system that recirculates filtrate from the precoat zone back through the filter medium in the working zone, where it passes through the filter cake, ensuring that only high-quality filtrate reaches the clean tank, and includes features like metering devices and pressure sensors to regulate the filtration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the filter medium is transported continuously over the filter bed to maintain permeability, then the pressure drop is kept within acceptable range, but the dirt particle content in the filtrate fluctuates due to the rhythmic transport of fresh and cake-loaded sections
Solution Approach 1:
The filter bed is divided into multiple zones (precoat zone and working zone) along the transport direction. The precoat zone receives fresh filter medium and generates filtrate with higher dirt content, while the working zone has established filter cake and produces high-quality filtrate. By segmenting the collection system into separate tanks for precoat filtrate and working zone filtrate, the patent prevents mixing of filtrates from different quality zones, thereby maintaining consistent overall filtrate quality while allowing continuous transport of the filter medium.
2Stress or pressure
If fresh filter medium is fed on the upstream side to maintain low pressure drop, then the filtering effect is reduced and the filtrate contains relatively large proportion of dirt particles
Solution Approach 1:
Different zones of the filter bed are assigned different functions: the precoat zone is designed to receive fresh filter medium and handle high dirt-content liquid, while the working zone maintains established filter cake for high-quality filtration. The collection system similarly assigns different tanks for different filtrate qualities. This local differentiation allows each zone to optimize its performance without compromising the other, resolving the contradiction between maintaining low pressure drop and ensuring effective filtration.
3Device complexity
If the filtrate from the precoat zone is routed directly to the clean tank, then the collection system is simpler, but the dirt particle content in the clean tank increases due to mixing with high-quality filtrate
Solution Approach 1:
The collection system is segmented into separate collection tanks for precoat zone filtrate and working zone filtrate. This segmentation prevents mixing of filtrates with different dirt particle contents, ensuring that only high-quality filtrate from the working zone is supplied to the clean tank. The separate routing, while increasing system complexity, is necessary to maintain consistent filtrate quality and protect downstream equipment.
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
This approach ensures a consistently high-quality filtrate by accelerating filter cake buildup and optimizing the filtration process, reducing dirt particle content and maintaining efficient filtration performance while minimizing pressure drops and potential damage to equipment.
Implementation Method 1
The passage of the liquid through the filter medium can be driven by gravity or by a pressure differential between the feed side and the filtrate side of the filter bed. The pressure gradient can be generated either by overpressure on the inlet side or by underpressure on the filtrate side.
Implementation Method 2
Dirt particles that are suspended in the liquid to be filtered are retained by the fine-pored filter medium.
Implementation Method 3
Within certain limits, the build-up of a filter cake on the filter medium is desirable because this filter cake in turn acts as a filter medium and improves the filtering effect, particularly for dirt particles with a small diameter.
Implementation Method 4
a circulation system is provided to direct the filtrate from the collection system back into the inlet chamber
Data Source
Figure 1
Figure 2
AI summary
Filter system for liquids, comprising a filter bed (12), a filter medium (14) transportable over the filter bed, an inlet chamber (10) for the liquid to be filtered bounded by the filter medium (14), and a clean tank (38) for the filtrate, characterized in that the filter bed (12) is divided in the transport direction of the filter medium (14) into an upstream precoat zone (34) and a downstream working zone (36), that a collection system (26, 16) separate from the clean tank (38) is provided for collecting the filtrate that has passed through the filter medium (14) in the precoat zone (34), and that a circulation system (18, 20, 22) is provided for returning the filtrate from the collection system (26, 16) to the inlet chamber (10).