Segmented Treatment Vessel Screen for Easy Cleaning Access

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Solution Overview

Problem

Current digester screen designs face challenges with limited access to withdrawal compartments due to blockages from precipitations, requiring high-pressure or acidic cleaning, and existing solutions either provide limited access or are prone to mechanical wear and chip column obstruction.

Innovation Solution

A screen design featuring a simple slide-in and slide-down mounting procedure with upper and lower flat tongues that allow for easy access to the withdrawal chamber, minimizing mechanical wear and obstruction, and incorporating a hinge mechanism for enhanced accessibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If screens with hinges are used to enable access to withdrawal compartment, then full visual view during cleaning is achieved, but mechanical wear on hinges and chip column obstruction occur

Engineering Contradiction:
Improveaccess to withdrawal compartmentVSAvoidmechanical wear and chip column obstruction
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The screen is divided into multiple individual staves that can be independently removed. This segmentation allows the withdrawal compartment to be accessed by removing only specific staves rather than using hinges that affect the entire screen structure, eliminating mechanical wear and chip column obstruction while maintaining cleaning access.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The screen design transitions from a fixed hinged structure to a dynamically configurable stave arrangement where individual staves can be selectively removed or positioned. This dynamic capability allows the screen to adapt between providing full coverage during operation and allowing access during cleaning without mechanical wear components.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If inspection covers are used to provide access to withdrawal compartment, then limited access is achieved, but full cleaning coverage is not possible

Engineering Contradiction:
Improveaccess to withdrawal compartmentVSAvoidcleaning effectiveness
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

Instead of using inspection covers that provide limited access to specific areas, the screen is segmented into individual removable staves. This allows the entire withdrawal compartment to be accessed by removing the necessary staves, enabling complete cleaning coverage throughout the compartment rather than limited access through covers.

Inventive Principle:
Principle #1Segmentation

3Ease of operation

If conventional hinged screens are used, then access to withdrawal compartment is enabled, but chip column movement is obstructed

Engineering Contradiction:
Improveaccess to withdrawal compartmentVSAvoidchip column flow
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The screen structure is segmented into individual staves that can be selectively removed rather than using a continuous hinged screen. This segmentation eliminates protruding hinge components that would obstruct the chip column, allowing uninterrupted chip flow while still enabling access to the withdrawal compartment when needed.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3387187B1Screen for treatment vessels
Publication Date: 2020.11.25 VALMET AB
  • EP3387187B1 patent drawingFigure 1
  • EP3387187B1 patent drawingFigure 2~4
  • EP3387187B1 patent drawingFigure 5a~7

AI summary

The invention relates to an improved treatment vessel screen (SC) for continuous treatment vessels. In order to obtain an easy cleaning of the withdrawal space behind screens in treatment vessels is the screen designed such that it may slide vertically into an upper recess of the screen frame and thereafter dropped into a mounting position wherein the lower part of the screen is locked radially in a lower recess of the screen frame. Exposing the withdrawal chamber for cleaning is simply a reversal of the mounting procedure, i.e sliding the screen upwards and then swinging the lower part of the screen out from mounting position. This inexpensive design prevent chip disturbance of column while allowing full access for cleaning of lower part of withdrawal space.