Pressure Screen Rotor Inlet Positioning for Pulsation Reduction
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Solution Overview
Problem
Existing pressure screens for processing paper pulp suspensions face high energy consumption and pulsation issues, leading to fluctuations in the weight per unit area of the fibrous web, which are difficult to dampen and require significant effort.
Innovation Solution
The distance between the axis of rotation and the centroid of the suspension inlet is reduced to less than 1.0 times the radius of the screen element, with a flow direction forming an angle of at least 10° with the sieve element, allowing the rotor to generate rotational flow and reducing energy consumption and pulsations, and an adjustable diaphragm influences the flow cross-section for optimal mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the suspension is injected tangentially to generate rotational flow, then the rotor can operate at higher speed, but energy consumption increases and pulsations are generated
Solution Approach 1:
The suspension inlet is pre-configured with a specific flow direction angle (at least 10° with the sieve element tangent) and optimized positioning (distance less than 1.0 times the radius from the rotation axis) to generate the necessary rotational flow before it reaches the rotor. This preliminary preparation allows the rotor to operate more efficiently at lower speeds while still achieving effective screening performance.
2Productivity
If the rotor operates at high speed to improve screening performance, then productivity increases, but pulsations are generated that cause fluctuations in web weight
Solution Approach 1:
The suspension inlet geometry and positioning are designed in advance to create a controlled flow pattern with a specific angle (at least 10° with the sieve tangent) before the suspension reaches the rotor. This pre-configured flow direction reduces the need for high rotor speeds, thereby minimizing pulsations and maintaining uniform web weight while still achieving effective screening.
3Stability of the object's composition
If the suspension inlet is positioned far from the rotation axis, then the flow distribution is more even, but the rotor effect is reduced and energy consumption increases
Solution Approach 1:
The distance between the suspension inlet and the rotation axis is optimized to be less than 1.0 times the radius of the screen element, and the flow direction is adjusted to form an angle of at least 10° with the sieve element tangent. These parameter changes create an optimal balance between flow distribution uniformity and rotor effectiveness, allowing the rotor to operate efficiently at lower speeds with reduced energy consumption.
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 configuration lowers energy consumption, reduces pulsations, simplifies the machine design, and optimizes rotor effect, ensuring efficient operation and even distribution of effects.
Implementation Method 1
the rotor is exclusively or predominantly responsible for generating the rotational flow in the inlet space
Implementation Method 2
The fibers contained in the suspension are intended to pass through the openings as accepts, while the solid components that are not desired are rejected
Implementation Method 3
pressure screens of the type considered here are provided with screen clearers, which have clearing surfaces that are moved past the screen
Implementation Method 4
the wing element gives off a pressure impulse at the front and a suction impulse behind it on the sieve to be cleared
Data Source
Figure 1~4
AI summary
The invention relates to a pressure screen for cleaning a fibrous suspension (1) with a screen element (2) formed rotationally symmetrical about a screen axis (7), which screen element divides the pressure screen into an infeed chamber (3) and an accepted stock chamber (4), the infeed chamber (3) being connected to a suspension infeed (11) and a reject outfeed (18) and the accepted stock chamber (4) to an accepted stock outfeed (13), and located in the infeed chamber (3) is a rotor (5) with rotor blades, the axis of rotation (10) of which corresponds to the screen axis (7), and which rotor rotates relative to the screen element (2). The intention is to reduce energy consumption and possible pulsations by the distance (15) between the axis of rotation (10) and the straight lines passing in the flow direction through the centroid (6) of the cross-sectional area extending perpendicularly of the direction of flow (14) of the suspension infeed (11) being less than 1.0 times, preferably less than 0.7 times, the radius of the screen element (2).