Feedwell Volute Sidewall for Uniform Thickener Discharge
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Solution Overview
Problem
Conventional tangential inlet feedwells in thickener/clarifier tanks experience high shear rates and non-uniform flow distributions, leading to uneven discharge and reduced efficiency, which can cause flocculant breakdown and disrupt sedimentation, resulting in decreased overall performance.
Innovation Solution
A feedwell design featuring a curved sidewall with volute, helical, or spiral surfaces that reduces localized fluid accelerations and velocities, providing a uniform distribution of discharge through a shape that guides the influent stream to dissipate energy progressively, thereby minimizing high shear rates and promoting even settling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional tangential inlet feedwell is used, then the influent feed stream can be delivered to the tank, but high shear rates and non-uniform flow distributions occur causing uneven discharge
Solution Approach 1:
The feedwell sidewall is designed with a curved surface that is a portion of a spiral, helix, coil, compound curve, or spline curve. This curved geometry guides the influent stream along a progressive path, dissipating energy gradually and producing a uniform discharge distribution while maintaining ease of feed stream delivery.
2Quantity of substance
If the feedwell diameter is increased, then more feed stream can be accommodated, but localized high shear rates and flow non-uniformities increase
Solution Approach 1:
The spiral-shaped curved sidewall distributes the feed stream flow progressively around the circumference, preventing concentration of flow in specific areas. This allows increased feed stream capacity while maintaining low shear rates through uniform distribution.
Solution Approach 2:
The curved sidewall geometry creates different flow characteristics at different locations around the feedwell circumference. The spiral shape ensures that each local area experiences appropriate flow conditions, preventing localized high shear rates even as overall capacity increases.
3Speed
If high fluid velocity is used in the feedwell, then faster feed stream delivery is achieved, but flocculant breakdown and sedimentation disruption occur
Solution Approach 1:
The spiral curved sidewall converts high-velocity feed stream into a progressive rotational flow pattern. This geometry maintains forward motion and feed stream delivery speed while distributing the flow uniformly, preventing localized high shear rates that would cause flocculant breakdown.
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 design achieves a uniform and efficient discharge distribution, reducing maximum fluid velocities and preventing flocculant breakdown, leading to improved settling efficiency and reduced disruption of sediment in thickener/clarifier tanks.
Implementation Method 1
guides the influent stream to dissipate energy progressively
Implementation Method 2
reduces localized fluid accelerations and velocities
Implementation Method 3
promoting even settling
Implementation Method 4
minimizing high shear rates
Data Source
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AI summary
A feedwell for a thickener/clarifier includes a feedwell body (40), a feedwell inlet (41), a sidewall (42), and a discharge opening (48). At least one infeed conduit (21) is connected at an upstream end of the feedwell inlet (41). The sidewall (42) has a non-cylindrical curved peripheral surface defining a radially-outermost fluid boundary surface for an influent stream (60). The non-cylindrical curved peripheral surface may include portions of a volute surface, coil surface, helical surface, compound curve surface, spline curve surface, or spiral surface. Feedwells according to the invention provide a uniform settling tank feeding flux around exiting portions of the feedwell, control velocity gradients and shear rates, protect flocculated aggregates, normalize sedimentation conditions in the settling tank, and prevent large local accelerations and flow non-uniformities.