Dual Separator Backwash Flume for Gas Liquid Distribution
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Solution Overview
Problem
In gravity filters, existing systems face challenges in preventing air from entering the backwash liquid during concurrent gas/liquid backwash and controlling the displacement of water into the filter tank, while ensuring uniform liquid distribution and maintaining a controlled water rise.
Innovation Solution
A backwash distribution apparatus with a second separator device in the main flume, positioned between the liquid opening and the first separator device, creates a second auxiliary flume to maintain a gas/liquid interface above the liquid opening, and includes liquid metering orifices to control the flow, preventing air from entering the liquid piping system and regulating water velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a common main conduit is used to distribute gas and liquid during backwash, then installation cost and complexity are reduced, but air may enter the liquid piping system and water displacement becomes uncontrolled
Solution Approach 1:
The main flume is segmented into multiple auxiliary flumes by installing separator devices that divide the single flow path into separate channels. This segmentation allows gas and liquid to be distributed through different paths, preventing air from entering the liquid piping system while maintaining the simplicity of a common main conduit structure.
Solution Approach 2:
Separator devices are introduced as intermediary elements within the main flume to control the interaction between gas and liquid flows. These separators act as mediators that regulate fluid distribution, preventing harmful air ingress while maintaining the integrated flume structure.
2Device complexity
If a single separator device is used in the main flume, then device complexity is reduced, but uniform liquid distribution and controlled water rise cannot be achieved
Solution Approach 1:
Multiple separator devices are installed in series within the main flume to create multiple auxiliary flumes. Each separator divides the flow further, ensuring uniform liquid distribution across the filter underdrains and controlling water rise levels through staged separation.
Solution Approach 2:
The separator devices are positioned at different vertical heights within the flume, creating a multi-level separation system. This vertical dimensionality allows precise control over liquid flow distribution and water level management while maintaining horizontal flow paths.
3Productivity
If the flume liquid metering orifice is positioned to control liquid flow, then liquid distribution is improved, but the gas/liquid interface may drop below the liquid opening allowing air entry
Solution Approach 1:
Multiple auxiliary flumes created by series-connected separator devices provide separate flow paths that maintain the gas/liquid interface above the liquid opening. The segmentation allows the orifice to control liquid flow while the multi-flume structure prevents air entry by maintaining proper interface positioning.
Solution Approach 2:
The separator devices serve as intermediaries that regulate the interaction between gas and liquid phases. They maintain the gas/liquid interface at appropriate levels relative to the liquid opening, preventing air entry while enabling controlled liquid distribution through the metering orifices.
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 solution effectively prevents air from entering the liquid piping system, controls water displacement, and ensures uniform liquid distribution during backwash, maintaining a stable water level and velocity within the main flume, thereby enhancing the efficiency and effectiveness of the backwash process.
Implementation Method 1
maintain a gas/liquid interface above the liquid opening
Implementation Method 2
liquid flows through said at least one metering orifice into said second auxiliary flume
Data Source
AI summary
A backwash distribution apparatus for a filter having a filter tank and a plurality of underdrain laterals includes a first and second separator device positioned in a common main conduit to define first and second auxiliary flumes. The first and second auxiliary flumes are in fluid communication with the common main conduit and the underdrain laterals. The first separator device has at least one flume liquid metering orifice preferably located near the bottom of the first separator device so that it may be below a gas liquid interface in the first auxiliary flume. The second separator device has either a weir edge or a plurality of metering orifices (or both) for passing backwash liquid from the common main conduit into the second auxiliary flume. The second separator device creates an adequate liquid pool in the common main conduit to prevent short circuiting of gas into a liquid opening for the common main conduit and also to provide low velocity flow of backwash liquid therein, while also providing uninhibited flow of backwash gas. The second separator also controls the distribution of backwash liquid and/or gas inside the common main conduit. A method for gas backwash in the presence of liquid according to the invention is also disclosed.