Backwash Header Design for Cloth Filter Cleaning
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Solution Overview
Problem
Current backwash shoes in cloth filters compress and dislodge solids, potentially contaminating filtered water, and lack effective turbulence for cleaning, while also allowing 'short-circuiting' of unfiltered effluent.
Innovation Solution
The design features a tubular body with slots and attached cylindrical rods forming open-ended sub-chambers that allow gradual straightening of filter fibers and prevent less clean fluids from entering, enabling efficient backwashing with reduced turbulence and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flat backwash shoe is used to clean the filter cloth, then the cleaning action is provided, but the leading edge compresses and dislorges solids out of reach of suction, potentially contaminating filtered water
Solution Approach 1:
The invention transitions from a flat, two-dimensional backwash shoe to a three-dimensional hood structure with internal cavities and sub-chambers. This dimensional change creates a volume above the filter cloth that allows solids to be lifted and contained within the hood structure, preventing them from being dislodged onto the filtered water side while maintaining effective suction cleaning action.
Solution Approach 2:
The hood structure acts as an intermediary chamber between the suction slot and the filter cloth surface. It provides a transition zone where solids can be captured and held within the internal cavities and sub-chambers, mediating between the cleaning action and the filtered water to prevent contamination.
2Ease of operation
If the flat underside of the backwash shoe is used, then contact with filter cloth is provided, but it does not provide volume of high turbulence to enhance cleaning scouring effect
Solution Approach 1:
The invention adds vertical dimension with the hood structure rising above the filter cloth, creating internal volume with sub-chambers. This three-dimensional structure generates high turbulence within the enclosed space, enhancing the scouring effect on the filter cloth surface while maintaining contact through the slot configuration.
Solution Approach 2:
The hood structure utilizes fluid dynamics and pressure differentials created by the suction system to generate high turbulence within the internal cavities and sub-chambers. The hydraulic action of water flowing through the structured hood enhances the cleaning scouring effect on the filter cloth.
3Device complexity
If the flat backwash shoe design is used, then simplicity is maintained, but it allows short-circuiting of unfiltered secondary effluent into the shoe
Solution Approach 1:
The hood structure serves as an intermediary barrier that prevents unfiltered secondary effluent from directly entering the suction system. The structured design with internal cavities and sub-chambers creates a controlled flow path that eliminates short-circuiting while maintaining system simplicity through integrated geometry rather than additional components.
4Object-affected harmful factors
If backwash shoes raise the shoe off the cloth surface, then compression of solids is reduced, but the impact of suction cleaning is weakened
Solution Approach 1:
The invention resolves this contradiction by moving the cleaning action to a different dimensional plane. The hood structure maintains elevation above the cloth surface to prevent solids compression, while the slot configuration and internal turbulence generation provide concentrated suction impact directly at the cloth interface, achieving both goals simultaneously through spatial arrangement.
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 design enhances cleaning efficacy, reduces backwash water requirements, and minimizes contamination, making cloth filters more cost-effective and easier to maintain while maintaining or exceeding the performance of previous designs.
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
allow the relatively clean fluid and solids previously adhered to the fibers to enter the open-ended chamber
Data Source
AI summary
A backwash header for a cloth filter 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 sized 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 an open-ended chamber defined by the structure and a portion of the exterior surface near the suction slot. The structure allows fluids and solids to enter the open-ended chamber and then the suction slot and cavity from a material being cleaned. Cloth filters and methods of treating water and wastewater using the backwash headers and cloth filters.