Screening Device Flow Guide for Pulp Suspension Stability
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Solution Overview
Problem
Existing screening devices for pulp suspensions face instability in flow patterns due to disturbances caused by the inlet flow, leading to speed and acceleration variations, turbulence, and difficulties in controlling the inlet flow speed.
Innovation Solution
A screening device with a flow guide extending from the inlet opening into the feed chamber, positioned tangentially or semitangentially, prevents the incoming inlet flow from meeting existing flow, maintaining stability and guiding it smoothly around the circumference, thus stabilizing the flow patterns and reducing turbulence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the inlet flow is introduced directly into the feed chamber without a flow guide, then the device structure is simple, but the flow pattern becomes unstable with turbulence and speed variations
Solution Approach 1:
A flow guide is introduced as an intermediary component between the inlet fitting and the feed chamber. This flow guide mediates the inlet flow by directing it tangentially along the feed chamber wall, preventing direct collision with existing flows and stabilizing the overall flow pattern while maintaining relatively simple device structure.
2Productivity
If the inlet flow speed is increased to improve screening efficiency, then productivity increases, but flow instability and turbulence worsen
Solution Approach 1:
The flow guide utilizes curved or angled surfaces to direct the inlet flow tangentially along the feed chamber wall. This curved flow path allows the inlet flow to be introduced at higher speeds while maintaining flow stability through smooth directional changes rather than abrupt collisions, thus improving screening efficiency without worsening flow instability.
3Quantity of substance
If the inlet fitting is positioned to maximize flow entry, then the inlet flow capacity is improved, but disturbances and turbulence in the feed chamber increase
Solution Approach 1:
The flow guide creates different flow conditions in different regions of the feed chamber. The inlet flow is directed along the wall in one region, while the center region maintains relatively undisturbed flow. This local differentiation allows maximum inlet flow capacity while minimizing disturbances in critical screening areas.
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
The solution achieves stable and uniform flow patterns within the screening device, allowing for controlled inlet flow speed and improved efficiency, reducing energy consumption and enhancing the screening process by minimizing disturbances and optimizing the rotor and foil area performance.
Implementation Method 1
a flow guide extending from the inlet opening in the housing of the screening device a distance inside the screening device and the flow guide inside the feed chamber of the screening device guides the inlet flow into the feed chamber of the screening device and prevents the incoming inlet flow not to meet the inlet flow already in the feed chamber of the screening device and thus the inlet flow remains stable
Implementation Method 2
a rotor arranged inside the cylindrical screening surface for rotating the pulp in the screen and foils or blades supported against the frame of the rotor such that when the rotor rotates, the blades produce on the screening surface a pressure pulse on account of which reject pulp and fibers collected onto the screening surface become released from the screening surface and return to the pulp suspension
Implementation Method 3
a screening cylinder and a rotor located and rotating inside the screening cylinder, which thus forms a housing around the screening cylinder. A commonly used screen type comprises the screening cylinder provided with a cylindrical screening surface equipped with apertures for screening pulp
Data Source
Figure 1~2
Figure 3
Figure 4A~4D
AI summary
The invention relates to a screening device for screening pulp suspensions and/or for stock preparation, which screening device (10) comprises a screening cylinder (12) and an inside the screening cylinder (12) located rotor (13) with foils (14) connected to the rotor (13) by foil arms (17), which screening device (10) comprises an inlet fitting (20) and a feed chamber (11) above of the screening cylinder (12) into which inlet flow of the pulp suspension is guided through the inlet fitting (20), which screening device (10) comprises a housing (25), which housing (25) has an inlet opening (28) for the inlet fitting (20). The screening device (10) comprises a flow guide (29, 30) extending from the inlet opening (28) in the housing (25) of the screening device (10) a distance inside the screening device (10) and that the flow guide (29, 30) inside the feed chamber (11) of the screening device (10) guides the inlet flow into the feed chamber of the screening device (10) and prevents the incoming inlet flow to meet the inlet flow already in the feed chamber (11) of the screening device (10).