Upward Sloping Density Current Baffle for Clarifier Tanks

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Solution Overview

Problem

Existing density current baffles in clarifier tanks are ineffective at low flow rates, unstable during sudden changes in flow, and fail to consistently redirect sludge back to the center of the tank, leading to high total suspended solids (TSS) in the effluent.

Innovation Solution

An upward sloping density current baffle design with a central portion attached to the tank side wall and an upper portion angled away from the wall, featuring a stiffening flange and vents to prevent gas buildup, allowing for improved flow redirection and stability across varying conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional density current baffles are used in clarifier tanks, then they can redirect sludge currents back toward the center, but they become ineffective at low flow rates and unstable during sudden flow changes

Engineering Contradiction:
Improvebaffle effectivenessVSAvoidperformance across varying flow rates
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The baffle is designed with an upward slope from the tank bottom rather than being vertical or downward-sloping. This dynamic geometry allows the baffle to effectively redirect density currents across a wide range of flow rates, including low flow conditions where traditional baffles fail. The upward slope creates a more stable flow pattern that maintains effectiveness during sudden flow changes such as those occurring after rain storms.

Inventive Principle:
Principle #15Dynamics

2Reliability

If baffles are positioned to redirect sludge currents, then TSS in effluent is reduced, but the baffle performance becomes dependent on unknown or changing sludge blanket height

Engineering Contradiction:
ImproveTSS reductionVSAvoidsludge blanket height
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

Instead of positioning the baffle horizontally at a specific height that depends on knowing the sludge blanket height, the invention uses a vertical dimension approach with an upward slope from the tank bottom. This dimensional change eliminates the need to know or measure sludge blanket height, as the upward-sloping geometry automatically adapts to different sludge levels while maintaining effective current redirection and TSS reduction.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If existing baffle designs are installed along the outer tank wall, then they can redirect density currents, but they allow hydraulic short circuits to bypass the main clarification volume

Engineering Contradiction:
Improvecurrent redirectionVSAvoidhydraulic short circuits
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

Traditional baffles slope downward or are vertical, but this invention inverts the approach by using an upward slope from the tank bottom. This inverted geometry more effectively blocks hydraulic short circuits that would otherwise bypass the main clarification volume, while still redirecting density currents back toward the center of the tank. The upward slope creates a more complete barrier that prevents both current escape and short-circuiting.

Inventive Principle:
Principle #13The other way round (Inversion)

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 baffle design significantly reduces TSS in the effluent by 80% compared to no baffle and 69% compared to prior art designs, while stabilizing flow during transient events like rainstorms, demonstrating enhanced performance and reliability.

Implementation Method 1

A major deterrent to effective solids removal is the presence of sludge density currents that form within the tank. These currents create hydraulic short circuits that bypass the tanks' main clarification volume and allow solids to enter the effluent.

Methodology Applied
Scientific EffectDensity current: Gravitational Convection (non heat)

Implementation Method 2

one or more relief openings are provided through the upward sloping panel to vent the pressure in a space formed between the junction of the lower side of the panel member and the peripheral tank wall.

Methodology Applied
Scientific EffectPressure venting: Pressure Gradient

Data Source

PatentUS7726494B2Density current baffle for a clarifier tank
Publication Date: 2010.06.01 NORTH AMERICAN FILTRATION ENTERPRISES LLC
  • US7726494B2 patent drawing
  • US7726494B2 patent drawing
  • US7726494B2 patent drawing

AI summary

A density current baffle for use in a clarifier tank maintains a first baffle portion having a lower end, an upper end and an intermediate central portion. The lower end of the baffle portion is coupled to a side wall of the clarifier tank and the upper end of the baffle portion is disposed, at a predefined angle, away from the side wall of the clarifier tank such that the first baffle portion slopes upwardly and away from the side wall.