Submerged Stirrer Rescue Slide for Cable Failure Retrieval

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Solution Overview

Problem

Existing immersion stirrers for biogas plants are disadvantaged as a defect in the agitator cable causes the stirrer to sink uncontrolled, making it difficult and costly to retrieve, often requiring expensive and time-consuming salvage operations.

Innovation Solution

A rescue slide is attached to the column below the agitator, allowing a recovery rope to be used to move the agitator back up, with a cable winch providing the necessary force to counteract gravity and facilitate repair, and a return rope for easier operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the agitator is lowered into the filling compound using the agitator cable, then the stirring function is achieved, but if the cable fails the agitator cannot be retrieved

Engineering Contradiction:
Improveagitator retrieval capabilityVSAvoidrescue system structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a rescue slide as an intermediary device that runs independently along the column. This slide acts as a mediator between the column structure and the agitator, allowing retrieval operations without depending on the agitator cable. The slide can be manually or motorized-operated to lift the agitator back to the surface even when the cable fails.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention implements a dedicated recovery mechanism that separates the retrieval function from the stirring function. The rescue slide is designed specifically for recovering the agitator in emergency situations, allowing the system to discard the failed cable while maintaining the ability to recover and reuse the expensive agitator component.

Inventive Principle:
Principle #34Discarding and recovering

2Ease of operation

If manual salvage operations are performed by removing filling material or using divers, then the agitator can be retrieved, but the process is expensive and time-consuming

Engineering Contradiction:
Improveagitator retrieval easeVSAvoidsalvage operation time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The rescue slide system enables self-service retrieval operations. The slide can be operated from the surface using a manual winch or motorized device, allowing the agitator to be recovered without needing to remove filling material or deploy expensive salvage divers. The system serves itself by providing an built-in retrieval mechanism that is always accessible.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The rescue slide is pre-installed and positioned along the column before any failure occurs. This preliminary preparation ensures that when a cable failure happens, the retrieval path is already established and ready for immediate use, eliminating the need for complex emergency setup procedures.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the agitator cable is used for both lowering and retrieving the agitator, then the system is simple, but a cable defect causes complete loss of retrieval capability

Engineering Contradiction:
Improveretrieval capability under failure conditionsVSAvoiddual cable system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention segments the retrieval function from the lowering function. The agitator cable handles only the lowering operation, while the rescue slide handles the retrieval operation. This segmentation ensures that a failure in one system (cable) does not affect the other system (slide), maintaining retrieval capability independent of cable status.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of using the same cable for both lowering and lifting, the invention inverts the approach by using a separate mechanical system (the slide running along the column) for retrieval. This reverses the conventional single-cable design and provides inherent fail-safe capability.

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

Enables simple and cost-effective retrieval of the agitator in case of a cable failure, reducing economic losses and operational complexity.

Implementation Method 1

a cable winch (20) for generating a force for moving the recovery slide (16) and the agitator (12) in the upward direction (2)

Methodology Applied
Scientific EffectGravitation: Gravitation

Implementation Method 2

The recovery slide (16) is displaceable along the column (14)

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3556458B1Submerged stirrer
Publication Date: 2021.09.22 THURWACHTER GMBH & CO
  • EP3556458B1 patent drawingFigure 1~3

AI summary

The invention relates to an immersion stirrer for a liquid container with a stirrer 12, which is slidably arranged on a column 14, wherein the stirrer 12 is connected to a stirrer rope 15 and by which the stirrer 12 can be guided in a height-adjustable manner along the column 14.