Screen Wheel Filter Melt Degradation Control
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Solution Overview
Problem
Screen wheel filters for highly viscous melts suffer from significant thermal and oxidation degradation during standstill periods, leading to melt loss and increased operational costs due to unnecessary screen insert changes and backwashing, especially when not all screen inserts are dirty or contaminated.
Innovation Solution
The screen wheel is driven for at least one complete revolution before changing or backwashing a screen insert, with adjusted speed and timing based on thermal or oxidation degradation behavior, ensuring ≤3% split molecular chains to minimize melt loss and only replace or clean inserts when necessary, thereby reducing unnecessary operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If screen inserts are changed or backwashed regularly to prevent degradation, then melt quality is maintained, but melt loss and operational costs increase significantly
Solution Approach 1:
The system uses differential pressure sensors to continuously monitor the contamination level of screen inserts and provides feedback signals to the control unit. This feedback mechanism enables the system to determine the actual cleaning or replacement needs based on real-time pressure differential data, rather than following a fixed schedule, thus avoiding unnecessary operations and melt loss.
Solution Approach 2:
The backwashing system is activated automatically based on the contamination level detected by the differential pressure sensors. When the pressure differential indicates that a screen insert is sufficiently contaminated, the system self-initiates the backwashing process without manual intervention, optimizing the balance between maintaining melt quality and minimizing melt loss.
2Reliability
If screen inserts are changed or backwashed frequently to prevent thermal and oxidation degradation, then melt quality is maintained, but productivity decreases due to longer standstill periods
Solution Approach 1:
The control unit receives continuous feedback from differential pressure sensors that monitor screen insert contamination levels. This real-time data allows the system to operate screen inserts until they actually require cleaning or replacement, minimizing unnecessary standstill periods and maintaining high productivity while ensuring melt quality through condition-based maintenance.
Solution Approach 2:
The system dynamically adjusts its operation based on actual contamination conditions rather than following a static, predetermined schedule. The control unit processes real-time pressure differential data and dynamically determines when backwashing or screen insert replacement is necessary, enabling flexible optimization of both productivity and melt quality.
3Loss of substance
If screen inserts are monitored and cleaned only when necessary, then melt loss is reduced, but the complexity of the control system increases
Solution Approach 1:
The control system uses straightforward feedback from differential pressure sensors to trigger backwashing or screen insert replacement only when contamination thresholds are exceeded. This feedback-based approach reduces melt loss by avoiding unnecessary operations while maintaining relatively simple control logic that monitors pressure differentials and activates cleaning processes based on predefined thresholds.
Solution Approach 2:
The system replaces complex manual monitoring and decision-making processes with automated electronic sensing and control. Differential pressure sensors and a control unit automatically monitor screen insert contamination levels and trigger appropriate actions, substituting mechanical/manual operations with electronic automation that reduces overall system complexity despite the added sophistication of automated control.
4Reliability
If the screen wheel rotates faster to reduce standstill time, then thermal and oxidation degradation is minimized, but the risk of material decomposition increases
Solution Approach 1:
The system uses differential pressure feedback to determine the actual need for screen insert cleaning or replacement. By monitoring contamination levels in real-time, the control unit can optimize the rotation speed and timing of screen insert changes to minimize both standstill periods (reducing thermal and oxidation degradation) and excessive rotation speeds (preventing material decomposition).
Solution Approach 2:
The system dynamically adjusts operational parameters including rotation speed and screen insert replacement timing based on contamination feedback. By changing these parameters adaptively rather than using fixed values, the system minimizes thermal and oxidation degradation during standstill periods while preventing material decomposition during high-speed rotation, optimizing material stability under varying conditions.
Data Source
Figure 1
AI summary
The invention relates to a method and a device for operating a screen wheel filter for highly viscous melts having pressures > 10 bar and temperatures > 90 °C which shall be further developed in such a way that less of the highly viscous melt is wasted and that the operation of the screen wheel filter can be made more economical. For this purpose the screen wheel (3) according to the invention is rotationally driven at least one complete revolution, with respect to one of the screen inserts (12) located in the melt channel (10), before the particular screen insert (12) is replaced and/or backflushed, and wherein the drive speed and drive cycling for the screen wheel (3) are set in dependence on the thermal or oxidative decomposition behavior of the particular melt in such a way that, when the particular screen insert (12) reenters the melt channel (10) of the screen wheel filter (1), the melt remaining in the particular screen insert (12) has experienced thermal decomposition or oxidative decomposition of ≤ 3% cleaved molecular chains, preferably ≤ 1% cleaved molecular chains.