External Wiper Mounting for Rotating Disc Dryer Maintenance
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Solution Overview
Problem
Current disc heat exchangers in the rendering industry face issues with wiper systems that are prone to damage due to clumped material, require complex and costly maintenance, and are difficult to adjust for varying disc spacing, leading to inefficiencies and downtime.
Innovation Solution
A rotating disc heat exchanger design with externally mounted wipers that include a pivot pin and shear pin mechanism outside the shell, allowing for adjustable positioning, easy replacement, and a counterweight or spring mechanism to prevent damage, with wiper components accessible from outside the shell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wipers are mounted internally within the shell, then they can effectively contact the discs to remove clumped material, but they become inaccessible for inspection and replacement, requiring shutdown and confined-space entry
Solution Approach 1:
The wiper mounting arrangement is inverted from the conventional internal mounting to external mounting. The wiper arm extends through the shell wall, with the mounting mechanism (bracket, pivot pin, shear pin) located on the external side of the shell. This allows operators to inspect, maintain, and replace wipers from the outside without entering the confined space of the shell or shutting down the dryer, while the wiping portion remains internally positioned to contact the discs.
2Strength
If wiper mounting brackets are welded internally to the shell, then they are securely fixed, but their position cannot be adjusted for varying disc spacing or thermal expansion
Solution Approach 1:
The wiper mounting system transitions from a static, fixed position to a dynamic, adjustable position. The bracket includes adjustment mechanisms (such as slots, holes, or movable mounting points) that allow the wiper arm to be repositioned along the shell wall. This enables adaptation to varying disc spacing due to manufacturing tolerances or thermal expansion, while maintaining secure attachment through the adjustable mounting configuration.
3Reliability
If shear pins are used to protect the wiper system from damage, then damage is prevented, but the sheared pins fall into the material and can damage other equipment
Solution Approach 1:
The shear pin mechanism is extracted from the internal space and relocated to the external side of the shell. When the shear pin breaks due to excessive force, the broken pieces remain outside the shell and do not contaminate the material being processed. The wiper arm can still pivot externally to disengage from the material, maintaining the protective function while eliminating the harmful effect of internal contamination.
4Reliability
If wipers are designed to pivot up upon shear pin failure, then damage is prevented, but the wiper may contact moving components or foreign bodies and cause further damage
Solution Approach 1:
A guide structure or housing is introduced as an intermediary element to control the wiper arm's motion during pivot-up operation. This guide ensures that when the shear pin fails and the wiper pivots, it follows a predetermined safe path that avoids contact with moving rotor components, disc-mounted agitators, or foreign bodies in the material. The intermediary structure channels the wiper's movement in a controlled manner, maintaining the protective function while eliminating secondary damage risks.
Data Source
AI summary
A rotating disc heat exchanger includes a shell defining an internal space for heat treating material via a plurality of rotatable discs located therein. A wiper includes a mount portion located outside of the internal space and a wiping portion that is located within the internal space. The shell includes a shell opening through which the at least one wiper extends. The mount portion includes a mount arrangement that is configured to enable: (i) adjustment of a position of the at least one wiper along a width of the shell opening; and/or (ii) removal and replacement of the at least one wiper from a location externally of the shell; and/or (iii) pivot of the at least one wiper about a pivot axis located externally of the shell, at least upon shear of a shear pin associated with the mount arrangement.