Gravity-Driven Sieve for Coating Impurity Separation
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Solution Overview
Problem
Current methods for separating impurities, particularly fibrous materials, in the machine circulation of coating and sizing stations are inefficient, leading to issues like streaks in paper production, sieve blockage, and high waste water loads, due to the limitations of existing sieving technologies which struggle to handle long fibers and require high-pressure operation.
Innovation Solution
The method involves using a sieve located beneath the coating or sizing station, leveraging the pressure difference created by the height difference between the station and the reservoir to facilitate sieving, allowing for finer mesh sizes and easier maintenance, and utilizing perforated-plate sieves to effectively separate fibrous impurities without disrupting the coating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanically cleaned pressure sieves with large gap widths (75-150 μm) are used, then the sieving capacity is high, but long fibrous impurities cannot be effectively separated and cause streaks in coating
Solution Approach 1:
The patent divides the sieving function into two separate stages: a first sieve with larger openings for removing coarse impurities and maintaining high flow capacity, and a second sieve with smaller openings for effectively removing fine fibrous impurities. This segmentation allows each sieve to be optimized for its specific function, resolving the contradiction between capacity and precision.
Solution Approach 2:
The patent introduces an intermediate chamber between the two sieves that serves as a transition zone. This intermediary structure allows the coating mixture to pass sequentially through both sieving stages, enabling the first sieve to handle high-volume coarse filtration while the second sieve provides fine filtration, thus mediating between capacity and precision requirements.
2Productivity
If the sieving element uses a single triangular wire with large gap width, then the capacity is high, but the sieve blocks easily when fibers become caught in the gap
Solution Approach 1:
The patent segments the filtration function across two sieves with different opening sizes. The first sieve with larger gaps handles high-volume flow with reduced blockage risk, while the second sieve with smaller gaps provides effective fine filtration. This segmentation distributes the blockage risk and maintains reliability.
Solution Approach 2:
The patent uses a two-stage sieving approach where the first sieve performs partial filtration of coarse impurities, and the second sieve performs additional filtration of fine impurities. This partial action at each stage prevents overwhelming either sieve, reducing blockage probability while maintaining overall reliability.
3Reliability
If high-pressure pumps are used to operate the sieve, then the sieving process is effective, but the system complexity and energy consumption increase
Solution Approach 1:
The patent positions both sieves at the same elevated height above the coating mixture reservoir, creating a hydrostatic pressure system where the pressure difference driving flow is generated by gravity rather than mechanical pumps. This equipotential arrangement eliminates the need for complex high-pressure pumping equipment while maintaining effective sieving.
Solution Approach 2:
The patent replaces the mechanical high-pressure pump system with a gravity-based hydrostatic pressure system. By elevating the sieves and utilizing the weight of the coating mixture in the reservoir, the system generates sufficient pressure differential for effective sieving without mechanical pumping, reducing device complexity.
4Ease of repair
If washable sieves operating on back-wash principle are used, then the sieves can be cleaned, but a considerable amount of waste water with coating content arises loading the mill's water-treatment system
Solution Approach 1:
The patent extracts the cleaning operation from the operational position by providing removable sieves that can be taken out and cleaned separately. This allows the sieves to be washed without removing them from the system, and the washing can be performed in a controlled manner that minimizes coating waste discharge into the general water treatment system.
Solution Approach 2:
The patent enables the recovery of coating material during sieve cleaning by allowing controlled washing of removed sieves. The washing process can be managed to recover coating substances that would otherwise be lost in back-wash systems, reducing the load on water treatment while maintaining ease of cleaning.
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 enhances fiber separation ability, reduces sieve blockage, minimizes waste, and allows for automatic washing, maintaining continuous operation while reducing the load on water treatment systems by effectively removing impurities without the need for high-pressure pumps.
Implementation Method 1
leveraging the pressure difference created by the height difference between the station and the reservoir to facilitate sieving
Implementation Method 2
The method involves using a sieve located beneath the coating or sizing station, leveraging the pressure difference created by the height difference
Data Source
AI summary
Method and arrangement for separating impurities from the machine circulation of a processing agent of a processing station used in processing paper or board, in which method the processing agent is led from a reservoir (1) to the processing station (2), where it is spread on the surface of the web being processed, and the excess processing agent led to the processing station (2) agent is led back to the reservoir (1). The flow of processing agent coming from the processing station (2) is led to at least one pressure sieve (6), which is located below the level of the processing station (2), in such a way that the feed pressure of the processing agent is created on the basis of the difference in height between the station (2) and the pressure sieve (6).