Mixing Silo Residence Time Distribution Switch

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Solution Overview

Problem

In plastic manufacturing plants, the transition time between product changes in mixing silos is lengthy due to the wide residence time distribution of bulk materials, leading to the creation of transition products that cannot be used until previous products are fully removed, resulting in significant material rejection.

Innovation Solution

A mixing silo system that alternates between a mixing function with wide residence time distribution and a flow function with narrow residence time distribution by using static mixing installations and shut-off elements, allowing for efficient operation according to the 'first in - first out' principle, ensuring minimal residual cross-sectional area for mass flow and reducing transition time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the mixing silo operates in mixing mode with wide residence time distribution, then bulk material mixing quality is improved, but transition time increases and material rejection increases

Engineering Contradiction:
Improvebulk material mixing qualityVSAvoidtransition time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the mixing silo operational mode switchable between mixing mode and flow mode. The system dynamically adjusts its residence time distribution characteristic based on operational requirements, allowing transition from wide residence time distribution (mixing mode) to narrow residence time distribution (flow mode) to reduce transition time during product changes.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameter of residence time distribution by switching between two distinct operating modes. In mixing mode, the system maintains wide residence time distribution for thorough mixing. In flow mode, the system achieves narrow residence time distribution (approaching plug flow) to minimize transition time and material rejection during product changes.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the mixing silo operates in mixing mode with wide residence time distribution, then bulk material mixing quality is improved, but the amount of rejected material increases

Engineering Contradiction:
Improvebulk material mixing qualityVSAvoidrejected material
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

The system dynamically switches operational modes to match process requirements. During normal operation, mixing mode provides thorough mixing quality. During product transitions, switching to flow mode minimizes the generation of transition products that would otherwise be rejected, thereby reducing material loss.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

By changing the residence time distribution parameter from wide to narrow during product transitions, the system reduces the volume of transition products that cannot be used. This parameter change directly addresses the material rejection problem while maintaining mixing quality during steady-state operation.

Inventive Principle:
Principle #35Parameter changes

3Loss of time

If the mixing silo operates in flow mode with narrow residence time distribution, then transition time is reduced, but bulk material mixing quality deteriorates

Engineering Contradiction:
Improvetransition timeVSAvoidbulk material mixing quality
Core Design Contradiction:
Loss of timeVSManufacturing precision

Solution Approach 1:

The system dynamically adjusts its operational mode based on the process stage. During product transitions, flow mode provides narrow residence time distribution for rapid clearing. During steady-state operation, mixing mode restores wide residence time distribution for thorough mixing quality. This dynamic switching resolves the contradiction between transition speed and mixing quality.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the residence time distribution parameter according to operational needs. In flow mode, narrow residence time distribution minimizes transition time. In mixing mode, wide residence time distribution ensures thorough mixing. The ability to switch between these parameter states resolves the contradiction.

Inventive Principle:
Principle #35Parameter changes

4Loss of substance

If the mixing silo operates in flow mode with narrow residence time distribution, then material rejection is reduced, but bulk material mixing quality deteriorates

Engineering Contradiction:
Improverejected materialVSAvoidbulk material mixing quality
Core Design Contradiction:
Loss of substanceVSManufacturing precision

Solution Approach 1:

The system dynamically switches between operational modes to optimize performance for different process stages. Flow mode minimizes material rejection during transitions, while mixing mode ensures thorough mixing during steady-state operation. This dynamic adaptation resolves the contradiction between reducing waste and maintaining quality.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

By changing the residence time distribution parameter from narrow to wide during steady-state operation, the system ensures thorough mixing quality. During transitions, switching to narrow residence time distribution minimizes material rejection. This parameter switching strategy resolves the contradiction between material efficiency and mixing quality.

Inventive Principle:
Principle #35Parameter changes

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 approach significantly reduces the transition time and material rejection by maintaining process performance and ensuring uniform bulk material quality, allowing for seamless product changes and efficient material handling.

Implementation Method 1

Mixing components influence the flow velocity of the bulk material in such a way as to generate a wide residence time distribution of the bulk material within the vessel

Methodology Applied
Scientific EffectResidence time distribution:

Implementation Method 2

At least one shut-off element is provided for the flow function, serving to shut off the at least one mixing unit

Methodology Applied
Scientific EffectFlow function:

Data Source

PatentEP4168168B1Mixing silo for bulk material, production plant with a mixing silo of this kind, and method for operating a mixing silo of this kind
Publication Date: 2024.03.20 COPERION GMBH
  • EP4168168B1 patent drawingFigure 1
  • EP4168168B1 patent drawingFigure 2
  • EP4168168B1 patent drawingFigure 3

AI summary

The invention relates to a mixing silo (4a) for bulk material comprising a silo container (11), a mixing fixture (16, 19) mounted in the silo container (11) for mixing the bulk material, at least one shut-off element (30) for shutting off the mixing fixture (16, 19), wherein the mixing silo (4a) has a minimum extraction rate and the silo container (11), with the mixing fixture (16, 19) shut off, has a residual cross-sectional area (26) which ensures a mass flow of the bulk material that is equal to or greater than the minimum extraction rate of the mixing silo (4a).