Curved Rotor Blades for Pulp Screen Energy Reduction
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Solution Overview
Problem
Conventional screens for cleaning fibrous pulp suspensions consume a lot of energy due to pressure and suction pulses, as well as turbulence generated by blades, leading to high operational costs and reduced service life of the screen basket.
Innovation Solution
The blades feature a curved leading edge and trailing edge with a wing-shaped profile, where the convex upper side faces the screen basket, and can be mounted parallel or slanted to optimize the angle with the spiral flow of the suspension, reducing local forces on the basket and improving flow patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional blades with straight leading and trailing edges are used, then the structure is simple and easy to manufacture, but energy consumption is high and screen basket service life is reduced due to excessive pressure pulses and turbulence
Solution Approach 1:
The blade design applies curvature to both the leading and trailing edges, replacing straight edges with arched envelope curves. This curvature modification optimizes the flow pattern around the blade, reducing turbulence and pressure pulses while maintaining structural integrity. The curved leading edge and curved trailing edge work together to create a more efficient flow distribution, directly addressing the high energy consumption issue without requiring complex additional components.
2Reliability
If blades generate strong pressure and suction pulses to prevent screen basket blockage, then cleaning performance is maintained, but local forces on the screen basket increase reducing its service life
Solution Approach 1:
The invention modifies the geometric parameters of the blade, specifically the curvature radius and arch shape of the envelope curves at the leading and trailing edges. By optimizing these parameters, the pressure pulse distribution is improved, reducing peak local forces on the screen basket while maintaining sufficient cleaning action. The curved geometry naturally distributes the hydraulic loads more evenly across the screen surface.
3Use of energy by moving object
If the blade has a wing-shaped profile with convex upper side facing the screen basket, then flow pattern is improved and energy consumption reduced, but manufacturing precision requirements increase
Solution Approach 1:
The wing-shaped profile is achieved through controlled curvature of the leading and trailing edges with defined arch envelope curves. While this improves flow characteristics and energy efficiency, it does require precise manufacturing to achieve the intended hydrodynamic performance. The curvature parameters are specifically designed to balance manufacturing feasibility with flow optimization.
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 reduces energy consumption while maintaining or improving cleaning performance, extends the service life of the screen basket, and allows for optimized dwell time of the pulp suspension, making it suitable for paper machine headbox screens with low pressure fluctuations.
Implementation Method 1
During operation, pressure and suction pulses as well as turbulence are generated by the blades 3 at the screen basket perforation
Implementation Method 2
During operation, pressure and suction pulses as well as turbulence are generated by the blades 3 at the screen basket perforation
Implementation Method 3
The blade which is spaced apart from the rotor has a cross-section with a wing-shaped profile according to the invention, where the convex upper side of the blade is facing the screen basket
Data Source
AI summary
The invention relates to a blade for screens for the treatment of a fibrous suspension, said blade being mountable on a rotor of the screen. According to the invention, the blade has a curved leading edge or curved envelope of the leading edge, the curvature extending in the direction of the trailing edge, and a curved trailing edge or curved envelope of the trailing edge, said curvature extending in the same direction as the other one. The invention also relates to a screen comprising a rotor on which the disclosed blades are mounted.