Feedwell Assembly Spin Inducement for Slurry Mixing

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Solution Overview

Problem

Thickener/clarifier tanks face challenges in enhancing the separation process of influent feed slurry due to high fluid velocity of the incoming influent feed stream, which causes turbulence and compromises the settling rate of solids, necessitating improved mixing and retention time of flocculents with the slurry.

Innovation Solution

A feedwell assembly with spin or rotation inducement elements in the infeed conduit, creating circular flow paths with upward and downward velocity components to enhance mixing and delay the descent of particulates, combined with a shelf or ledge to increase retention time and mixing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the influent feed stream is introduced at high fluid velocity, then the throughput of solids is enhanced, but turbulence is caused that compromises the settling rate of solids

Engineering Contradiction:

Improvethroughput of solidsVSAvoidsettling rate of solids

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The feedwell assembly segments the high-velocity influent stream into multiple flow paths using spin inducement elements, distributing the energy dissipation across different zones rather than allowing a single turbulent flow path that would compromise settling

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spin inducement elements create curved, circular flow paths within the feedwell, transforming the linear high-velocity stream into rotational motion. This curvature allows gradual energy dissipation while maintaining solid suspension, preventing premature settling and turbulence in the main tank

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Stability of the object's composition

If the influent feed stream energy is dissipated quickly, then turbulence is reduced, but the mixing time of flocculents with slurry is insufficient

Engineering Contradiction:

Improvesettling rate of solidsVSAvoidmixing time of flocculents

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The feedwell assembly creates a dynamic, rotating flow pattern that evolves over time. The spin inducement elements generate initial rotational energy that gradually dissipates, providing extended mixing time for flocculents while ultimately reducing turbulence before solids enter the settling zone

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The circular flow paths created by the spin inducement elements produce periodic motion patterns that enhance mixing through repeated circulation. This periodic action maintains flocculent-slurry contact over an extended period while the rotational energy gradually diminishes, avoiding sustained turbulence

Inventive Principle:

Principle #19Periodic action

3Stability of the object's composition

If spin or rotation inducement elements are added to the infeed conduit, then mixing of flocculents with slurry is enhanced, but the device complexity increases

Engineering Contradiction:

Improvemixing efficiency of flocculentsVSAvoidfeedwell assembly structure

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The spin inducement elements are designed to utilize the kinetic energy already present in the influent stream to generate rotational motion. The structure self-activates through the flow itself, eliminating the need for external motors or power sources, thereby enhancing mixing without proportionally increasing operational complexity

Inventive Principle:

Principle #25Self-service

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 solution improves the mixing of flocculents with the slurry, delays the descent of particulates, and increases the retention time within the feedwell, leading to enhanced settling efficiency and solids recovery in thickener/clarifier tanks.

Implementation Method 1

at least one spin or rotation inducement element disposed as part of the infeed conduit for imparting rotation or spin to a slurry stream fed to the feedwell body via the infeed conduit

Methodology Applied

Scientific EffectRotation:

Implementation Method 2

the spin or rotation inducement element is configured for providing the slurry stream with an upward velocity component at the inner boundary of the circular path

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Implementation Method 3

Settling of solids may be enhanced in some applications by the addition of a flocculent or polymer that forms agglomerates that settle more readily

Methodology Applied

Scientific EffectFlocculation: Flocculation

Implementation Method 4

the influent is retained for a period long enough to permit the solids to settle out by gravity from the fluid

Methodology Applied

Scientific EffectSedimentation: Sedimentation

Data Source

PatentUS8889012B2Thickener/clarifier feedwell assembly with infeed rotation

Publication Date: 2014.11.18 F L SMIDTH & CO AS

AI summary

A feedwell assembly for a thickener/clarifier includes a feedwell body, at least one infeed conduit connected at a downstream end to the body, and at least one spin or rotation inducement element disposed as part of the infeed conduit for imparting rotation or spin to a slurry stream fed to the feedwell body via the infeed conduit. The spin or rotation inducement element may be a fixed and rigid structural member such as a vane or baffle, or include actively operated elements. Multiple such spin or rotation inducement elements may be provided in various locations in or adjacent the infeed conduit.