Backwash Header Design for Cloth Disk Filter Cleaning
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Solution Overview
Problem
Current backwash mechanisms in cloth disk filters are inefficient, often contaminating filtered water by forcing solids through the cloth, failing to enhance cleaning turbulence, and wearing out the filter material due to sharp edges, leading to frequent filter clogging and high reject rates.
Innovation Solution
The introduction of redesigned backwash headers with slotted tubular bodies and hood structures that allow clean fluid to pass through the filter material in reverse direction, capturing solids while preventing unclean fluids from entering, and featuring cylindrical rods to form sub-chambers for gradual fiber straightening and relaxing, thereby enhancing cleaning efficiency and reducing wear on the filter cloth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a flat backwash shoe with suction orifices is used, then solids can be removed from the filter cloth, but the leading edge compresses and forces solids through the cloth to contaminate the filtered water
Solution Approach 1:
The backwash shoe design inverts the traditional flat configuration by using a rounded leading edge that flows over the cloth surface rather than compressing against it. This reversal of the geometric relationship prevents solids from being forced through the cloth while still allowing effective solids removal through the suction orifices.
Solution Approach 2:
The backwash shoe employs a rounded or curved leading edge instead of a flat surface. This curvature allows the shoe to glide over the filter cloth during backwashing, creating turbulence that lifts solids for removal without compressing the cloth and forcing particles through to contaminate the filtered water.
2Duration of action of stationary object
If the backwash shoe is raised off the cloth surface, then cloth wear is reduced, but the suction cleaning effectiveness is weakened
Solution Approach 1:
The backwash shoe utilizes hydraulic principles by allowing filtered water to flow through the shoe structure, creating a hydrodynamic cushion that maintains optimal spacing from the cloth. This pneumatic-hydraulic approach provides both cleaning effectiveness and cloth protection simultaneously.
Solution Approach 2:
The backwash shoe applies suction force selectively at specific zones rather than uniformly across the entire contact area. This partial action concentrates cleaning power where needed while reducing overall mechanical stress on the cloth, extending its service life.
3Ease of manufacture
If a non-metallic backwash shoe is used, then fabrication cost is reduced, but the shoe abrades and frays the cloth surface over time
Solution Approach 1:
The invention changes the surface parameter of the backwash shoe from sharp edges to a rounded, smooth surface. This parameter modification reduces mechanical abrasion on the filter cloth while maintaining the structural integrity and cleaning effectiveness of the shoe.
Solution Approach 2:
The backwash shoe may utilize composite material construction that combines the cost advantages of non-metallic materials with surface treatments or coatings that reduce abrasiveness. This composite approach balances fabrication economy with cloth protection.
4Device complexity
If a flat backwash shoe is used, then the structure is simple, but it does not provide sufficient turbulence to enhance the cleaning effect
Solution Approach 1:
The rounded leading edge of the backwash shoe creates turbulence as water flows around it during the backwashing process. This curvature-induced turbulence enhances the cleaning effect by lifting and suspending solids for more effective removal, while adding minimal complexity to the overall shoe structure.
Solution Approach 2:
The backwash shoe design incorporates dynamic flow patterns through its rounded geometry, allowing the water flow to adapt and create varying turbulence levels during operation. This dynamic approach enhances cleaning effectiveness without requiring complex mechanical components.
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 new backwash headers improve cleaning efficiency by allowing simultaneous cleaning of two surfaces, reducing backwash water requirements, minimizing filter cloth abrasion, and extending the lifespan of the filter material, leading to lower energy costs and increased filter run times.
Implementation Method 1
allow relatively clean fluid to pass through the filter material in a reverse direction upon application of a suction pressure in the internal cavity
Implementation Method 2
the sub-chambers have sufficient volume to allow gradual straightening and relaxing of fibers of a filter material being cleaned by the apparatus
Data Source
AI summary
A backwash header for a cloth filter disk includes a body having a length a diameter, first and second ends, a longitudinal axis, and an exterior surface, the body defining at least one internal cavity. The body includes at least one suction slot configured to allow fluids and solids to enter the internal cavity from outside of the exterior surface. A structure is attached to a portion of the exterior surface of the body around and extending away from the suction slot to form a chamber defined by the structure and a portion of the exterior surface near the suction slot. The structure is configured to allow fluids and solids to enter the chamber and then the suction slot and cavity from a material being cleaned. Cloth disk filters and methods of treating water and wastewater using the backwash headers and cloth disk filters.