Filter Washing Method for Seawater Using Air Blowing
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Solution Overview
Problem
Conventional filter washing methods for raw water filters, particularly those with multiple layers like sand and anthracite, face challenges with the formation of 'mud balls' due to agglomeration, leading to prolonged washing times and media loss, especially when treating seawater with alginates or natural polymers.
Innovation Solution
A method involving depressurization, air bubbling to break down cakes, followed by short water rinsing to separate media, and repeated cycles to ensure efficient cake reduction and media preservation, without overloading the weir or causing media loss, utilizing a controlled sequence of air and water injection and evacuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional washing methods are used with prolonged rinsing to remove mud balls, then the filter media can be cleaned, but the washing duration becomes excessively long and media loss occurs
Solution Approach 1:
The washing process is divided into distinct sequential phases: air blowing phase to break up mud balls, followed by water rinsing phase to remove particles. This segmentation allows each phase to perform its specific function efficiently, reducing overall washing time while maintaining cleaning effectiveness.
Solution Approach 2:
The washing operation uses periodic alternation between air blowing and water rinsing cycles. The air blowing phase breaks down cakes, and the water rinsing phase removes the broken particles. This periodic action prevents media loss by limiting water contact time, while still achieving thorough cleaning.
2Reliability
If prolonged water rinsing is applied to evacuate cakes from the filter, then cleaning is achieved, but filter medium is lost with the washing waters
Solution Approach 1:
Air blowing is applied before water rinsing to pre-break up the mud balls and cakes. This preliminary action reduces the size and adhesion of cakes, making them easier to remove with brief water rinsing, thereby preventing media loss while achieving effective cake removal.
Solution Approach 2:
The method replaces prolonged mechanical water rinsing with a combination of pneumatic action (air blowing) followed by brief hydraulic rinsing. The air blowing mechanically breaks up cakes without water, and the subsequent short water phase removes particles efficiently, reducing media loss.
3Device complexity
If air and water are injected simultaneously during washing, then the process is simplified, but media particles are not effectively separated and cakes are not reduced
Solution Approach 1:
The washing process is segmented into distinct air blowing and water rinsing phases rather than simultaneous injection. This segmentation allows air to perform cake breakdown while water performs particle removal, achieving effective media separation without complicating the overall process design.
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 method significantly reduces washing duration, preserves filter media, and prevents media loss by breaking down 'mud balls' through friction and short rinsing cycles, enhancing filtration efficiency and production yield.
Implementation Method 1
pressurized air alone is blown into the lower part of the filter, this air passing through the layers of the filter from bottom to top and causing, in particular by friction, the reduction of the cakes into particles
Implementation Method 2
rinsing is carried out with water alone, from bottom to top, which makes it possible to separate the media and bring the particles to the surface
Data Source
Figure 1~3
AI summary
The invention relates to a method for washing a filter (F) having at least two layers of filtering media (4, 5) for raw water containing components having a tendency to form cakes (M), in particular for seawater, the layers of filtering media being supported by a base (6) comprising pass-through openings and provided with nozzles (6a) enabling air and/or wash water to be injected, the raw water flowing through the layers from top to bottom and the treated water being recovered at the lower portion of the filter, and which comprises at least one spillway (D) at the upper portion thereof for collecting the wash water. The method includes the following series of steps: a) the raw water intake (2)is closed, followed by the filtration outlet valve (13), the filter is depressurized, and the filter cake is broken; b)the water level in the filter is lowered; c) only pressurized air is blown into the lower portion of the filter, said air passing through the layers of the filter from bottom to top and causing the cakes to be reduced to particles, in particular by means of friction; d) rinsing is carried out from bottom to top using only water, the water rinsing time being sufficiently short to ensure that the water level stops below the level of the upper edge of the wash water collection spillway; e) the filter water is emptied once again by discharging same from the lower portion of the filter; f) steps c), d) and e) are repeated at least once, and a final rinsing is carried out by injecting a quantity of backwashing water through the bottom portion of the filter, which is then discharged from the upper portion of the filter via a pipe (14).