Dual-Layer Granular Filter with Density-Graded Media
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Solution Overview
Problem
Existing water filtration systems with multiple layers of granular media face challenges in achieving both high-quality filtered water and long filtration cycle durations due to the limitations in particle size and density ratios, leading to compromised retention capacity and water quality.
Innovation Solution
A water filtration device with a first layer of high-density grains and a second layer of lower-density grains, where the ratio of average grain diameters is between three and six, allowing for efficient mixing and reclassification during the washing phase, with a cleaning fluid injection speed that expands the second layer by 2-10%, enabling gravity flow and reformation of layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a filter uses media with small particle size to improve water quality and retention capacity, then the cutoff threshold and particle retention rate improve, but the filtration cycle duration becomes too short for industrial operation
Solution Approach 1:
The filter bed is divided into multiple layers with different media types and particle sizes. The lower layer contains coarser media while the upper layer contains finer media, allowing each layer to perform different filtration functions. This segmentation enables the system to achieve both high retention capacity and long cycle duration by distributing the filtration load across layers with optimized particle sizes.
Solution Approach 2:
Different regions of the filter bed are assigned different media properties tailored to local requirements. The lower layer uses coarser media suitable for initial particle capture and structural support, while the upper layer uses finer media for polishing and achieving the required cutoff threshold. This local optimization of media properties resolves the contradiction between retention capacity and cycle duration.
2Duration of action of moving object
If a filter uses media with large particle size to extend filtration cycle duration, then the cycle duration improves, but the water quality and retention capacity deteriorate
Solution Approach 1:
The filter bed is divided into multiple layers with different media types and particle sizes. The lower layer contains coarser media while the upper layer contains finer media, allowing each layer to perform different filtration functions. This segmentation enables the system to achieve both high retention capacity and long cycle duration by distributing the filtration load across layers with optimized particle sizes.
Solution Approach 2:
Different regions of the filter bed are assigned different media properties tailored to local requirements. The lower layer uses coarser media suitable for initial particle capture and structural support, while the upper layer uses finer media for polishing and achieving the required cutoff threshold. This local optimization of media properties resolves the contradiction between retention capacity and cycle duration.
3Productivity
If the ratio of grain diameters between layers is increased to improve mixing and reclassification during washing, then washing efficiency improves, but material loss increases
Solution Approach 1:
The patent optimizes the grain diameter ratio parameter to a specific range (3-6 times) that balances washing efficiency with material retention. This parameter optimization ensures that during backwashing, the coarser lower layer media can be effectively fluidized and cleaned without causing excessive loss of the finer upper layer media through interstices.
Solution Approach 2:
The patent accepts controlled material loss as a trade-off for achieving effective washing, particularly of the lower layer media that is easier to replace. By designing the system to tolerate replacement of coarser media while protecting finer media, the overall system maintains high washing efficiency without excessive operational costs.
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 configuration achieves high-quality filtered water with extended filtration cycle durations, improved retention of suspended matter, and reduced energy consumption, while maintaining effective washing efficiency and minimizing material loss.
Implementation Method 1
the second media has a fluidization speed greater than that of the first media, and means for injecting a cleaning fluid are provided at floor level to inject the fluid with a speed such that the second media expands by a value comprised between 2% and 10%
Implementation Method 2
the ratio of the average grain diameters Db/Da is such that between the grains of the second media there are interstices having sufficient dimensions to allow, after cleaning, a gravity flow of the grains of the first media through the second layer
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a water filtration device that comprises a floor (2) above which are provided a first layer (5) of a first medium (A) containing high density grains with a mean diameter Da, and a second layer (6) of a second medium (B) containing grains having a mean diameter Db and a density lower than that of the first medium (A), Db being higher than Da. An inlet (7) for the water to be filtered is provided in the upper portion and a filtered water outlet (8) is provided under the second layer. The mean diameter Db is such that the particles of the second medium (B) are separated by gaps having a size which is sufficient to allow the gravity flow of particles pf the first medium (A). The second medium (B) has a fluidisation rate which is higher than that of the first medium (A), and means (I) for injecting a cleaning fluid are provided at the floor (2) for injecting a fluid at a speed such that the second medium (B) expands by a value of between 1 and 10 %.