Basket Screen Rotor Vanes for Low-Wear Pulp De-Flaking
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Solution Overview
Problem
Disc-type screens in the paper industry suffer from high power consumption, rapid wearing of components, and require large machine sizes due to uneven wear patterns and limited screening area, while existing designs with Hydro-foil rotor vanes cause impurity tangling and accumulation.
Innovation Solution
A pulp screening machine with a basket-type screen and cantilevered rotor vanes outside the screen, featuring an 'in-flow' design with separate pulp and reject outlets, and optional projecting strips or grooves on the screen surface to enhance de-flaking and reduce wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If disc-type screens with high rotor tip speed are used, then de-flaking efficiency is improved, but power consumption increases and wearing accelerates
Solution Approach 1:
The patent changes the operational parameters by using a basket-type screen with rotor vanes that operate at lower tip speeds compared to conventional disc-type screens. The basket configuration allows effective screening and de-flaking at reduced speeds, thereby lowering power consumption while maintaining productivity.
Solution Approach 2:
The patent employs a basket-type screen with curved or spherical geometry instead of a flat disc configuration. This curvature increases the screening surface area and improves pulp flow dynamics, enabling effective screening at lower rotor speeds and reducing power requirements.
2Productivity
If disc-type screens with high rotor tip speed are used, then de-flaking efficiency is improved, but wearing of rotor and screen plate accelerates
Solution Approach 1:
The patent reduces the operational tip speed parameter, which directly decreases the mechanical stress and friction between the rotor vanes and screen surface. This parameter change significantly reduces wearing rates and extends the service life of both the rotor and screen components.
Solution Approach 2:
The basket-type screen configuration with its curved geometry distributes the mechanical loads more evenly across the screen surface and rotor vanes, reducing concentrated stress points and minimizing wearing compared to flat disc configurations.
3Productivity
If flat screen plate is used, then de-flaking efficiency is improved, but screening area is reduced and machine size increases
Solution Approach 1:
The patent uses a basket-type screen with curved or spherical geometry that provides significantly larger screening surface area compared to flat disc configurations. The curvature allows the screen to enclose a larger volume, increasing the effective screening area without proportionally increasing machine footprint.
Solution Approach 2:
The basket configuration transitions from a two-dimensional flat screen surface to a three-dimensional enclosed structure, utilizing vertical and radial spaces more effectively. This dimensional change maximizes screening area within a compact machine envelope.
4Stability of the object's composition
If rotor vanes are connected via rings, then position stability is improved, but impurity tangling and accumulation occurs
Solution Approach 1:
The patent removes the connecting rings from the rotor vane assembly, extracting the source of impurity tangling and accumulation. The rotor vanes are designed to operate effectively without these rings, eliminating the harmful effect while maintaining structural integrity through alternative design features.
Solution Approach 2:
The patent segments the rotor vane structure into independent or loosely connected elements that do not require ring connections. This segmentation eliminates the ring-impurity interaction problem while maintaining rotor vane positioning through individual mounting or flexible connection methods.
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
Reduces power consumption and wear, increases screening area efficiency, and allows for smaller machine size, while effectively de-flaking and removing coarse impurities with minimal fiber loss.
Implementation Method 1
the rotor vanes thus have some flexibility in that unslushed paper flakes (fiber bundles) can be de-flaked between the cantilevered rotor vanes and the screen
Implementation Method 2
the disclosed 'in-flow' operating design according to this invention brings the beneficial effect that it reduces wearing to the screen inside due to the centrifugal forces
Data Source
AI summary
A pulp screening machine has screen extending upward from the bottom of the pulp screening machine and a rotor which rotates around the outside of the screen. An accept outlet is provided inside the screen and a pulp outlet and reject outlet are provided outside of the screen. The rotor vanes of the rotor are cantilevered from the rotor base on top of the screen into the region of the screen, with the rotor vanes not being connected to each other in the region of the screen. The rotor vanes have a rigidity adaptable for de-flaking cooperatively with the outside surface of the screen.