Toroid Separation Chamber Rotor Dynamics for Pulp Screening
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Solution Overview
Problem
Conventional screening and dewatering apparatuses in pulp processing face inefficiencies due to high pulp concentration leading to thickening, which limits capacity and efficiency, and requires large machines with low surface efficiency, restricting pulp concentration to around 5-6%.
Innovation Solution
A toroid-shaped separation chamber with a rotor creating a circular flow and tangential inlet to maintain high velocity over the barrier, allowing for efficient dewatering and separation with reduced energy consumption and smaller apparatus size, enabling higher pulp concentrations without clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pulp concentration is increased to improve screening capacity, then the throughput increases, but the fibre network strength increases causing clogging and reduced separation efficiency
Solution Approach 1:
The rotor speed is varied along the screening zone to dynamically adjust energy supply. The rotor rotates faster at the inlet where pulp concentration is lower and slower at the outlet where concentration increases, preventing fibre network formation while maintaining screening efficiency throughout the zone
Solution Approach 2:
The rotational speed parameter of the rotor is changed along the length of the screening zone. By reducing rotor speed as pulp concentration increases, the energy input is adapted to prevent excessive fibre network strength development, allowing higher overall concentrations without clogging
2Strength
If the rotor speed is increased to maintain energy supply for high concentration pulp, then the fibre network breaks up better, but the turbulence level becomes excessively high reducing separation selectivity
Solution Approach 1:
The rotor speed parameter is varied along the screening zone to optimize the balance between fibre network breakdown and separation selectivity. Lower speeds in the outlet region reduce turbulence while maintaining sufficient energy for separation, preserving selectivity
3Manufacturing precision
If the screening zone length is increased to improve separation efficiency, then more thorough separation is achieved, but the thickening effect increases causing capacity reduction
Solution Approach 1:
The rotor speed is dynamically reduced along the screening zone to compensate for the thickening effect. This allows a longer screening zone to be effective without the capacity penalty, as the decreasing energy input matches the increasing pulp concentration and prevents fibre network formation
4Reliability
If dilution is applied before screening to reduce pulp concentration, then clogging is prevented, but additional process steps and energy consumption for dilution and subsequent thickening are required
Solution Approach 1:
The rotor speed parameter is optimized to process higher concentration pulp directly without dilution. By matching energy supply to local pulp concentration through variable speed rotation, the system prevents clogging while eliminating dilution and thickening steps, reducing overall process complexity
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 design enhances separation efficiency, reduces the need for dilution and thickening, and allows for higher pulp concentrations, preventing clogging and increasing the capacity and efficiency of the screening process while maintaining high dewatering effectiveness.
Implementation Method 1
The interaction between the moving rotor blades and the protrusions of the screen member cause pressure pulsations and/or shear forces and turbulence, which can fluidize the pulp
Implementation Method 2
the rotor is arranged to both create a circular flow of the incoming pulp suspension in the toroid shaped separation chamber
Implementation Method 3
The interaction between the moving rotor blades and the protrusions of the screen member cause pressure pulsations and/or shear forces and turbulence
Implementation Method 4
it causes heavier particles, dirt and like reject material to be passed radially outwardly to the reject outlet
Data Source
Figure 1a~1b
Figure 1c~1e
Figure 2a~2d
AI summary
The invention relates to an apparatus (1, 1a, 1b) for separating particles in a pulp suspension, which apparatus (1, 1a, 1b) comprises a housing (14), a barrier (2, 2a, 2b) with apertures, an inlet (3, 3a, 3b) for the pulp suspension, a first outlet (4, 4a, 4b) for material with large particles not having passed the barrier (2, 2a, 2b), a second outlet (5, 5a, 5b) for material with small particles having passed the barrier (2, 2a, 2b), and a rotor (6) on an axis (9), which rotor (6) is arranged to create a fluidization zone (8, 8a, 8b) near the barrier (2, 2a, 2b). According to the invention the apparatus (1, 1a, 1b) comprises a separation chamber (7, 7a, 7b) having a toroid shape. The rotor (6) is arranged to both create a circular flow of the incoming pulp suspension in the separation chamber (7, 7a, 7b) and to clean the barrier (2, 2a, 2b) from the pulp suspension.