Flow Guide Device for Cylinder Paper Machine Trough Inlet
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Solution Overview
Problem
Paper machines with DC cylinder molds lack controlled speed profiles between the entry of fibrous stock suspension and the screen cylinder, leading to negative velocity gradients, backflows, and unfavorable flocculation, which affects the precision of security thread placement and the strength properties of the paper.
Innovation Solution
The introduction of a flow guide device with a cover and flexible skirt that accelerates and directs the suspension flow, allowing for adjustable speed profiles and precise thread placement, along with a suspension storage box to regulate pressure and flow conditions, ensuring no backflows or dead zones and enabling independent adjustment of speed at the channel transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an open trough surface is used for fiber suspension flow, then the structure is simple, but negative velocity gradients and backflows occur leading to poor flow control
Solution Approach 1:
A flexible membrane is introduced to cover the open trough surface, creating a closed flow channel. The membrane can be adjusted to control the channel geometry and flow characteristics, eliminating the open surface problems while maintaining structural simplicity.
Solution Approach 2:
A flow guide device with adjustable baffle is introduced as an intermediary element to control the fiber suspension flow. This baffle regulates the velocity profile and prevents backflow, improving flow control without significantly complicating the overall trough structure.
2Productivity
If papermaking speed is increased, then productivity improves, but thread positioning accuracy deteriorates due to cross-currents
Solution Approach 1:
A thread guide device is introduced as an intermediary between the suspension flow and the forming wire. This guide stabilizes the thread position and reduces the impact of cross-currents, allowing high-speed operation while maintaining precise thread placement accuracy.
Solution Approach 2:
A adjustable baffle or membrane is used to control the flow velocity profile, creating a more uniform flow that reduces cross-currents. This allows higher papermaking speeds without compromising thread positioning precision.
3Manufacturing precision
If a defined headbox with controlled velocity profile is introduced, then flow conditions improve, but device complexity increases
Solution Approach 1:
Instead of a complex rigid headbox structure, a flexible membrane is used to define the flow channel. This membrane can be adjusted to create the desired velocity profile while keeping the overall structure simpler and more adaptable than a traditional headbox.
Solution Approach 2:
The flow control system uses adjustable, movable elements (such as adjustable baffles or membranes) rather than fixed structures. This allows the velocity profile to be optimized for different operating conditions without requiring a completely different structure, balancing control precision with structural simplicity.
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 solution improves flow conditions, increases paper production speed, and enhances the accuracy of security thread placement, resulting in better fiber orientation and strength properties of the paper.
Implementation Method 1
a flow guide device with a cover and flexible skirt that accelerates and directs the suspension flow
Implementation Method 2
a suspension storage box to regulate pressure and flow conditions
Implementation Method 3
a trough with a DC rotary drum screen rotating therein
Data Source
Figure 1
Figure 2
Figure 2a
AI summary
The invention relates to a paper machine for producing paper or paper-like material webs, wherein the device comprises a machine-wide fibrous suspension inlet (4), a trough (1) with a direct current circular screen (2) rotating therein, a trough inlet (8) and a non-woven take-off device (14). According to the invention, the trough inlet (8) has a flow-guiding device (20), wherein said flow-guiding device (20) comprises a cover (19) that covers the suspension level (A1) of the fibrous suspension and accelerates continuously the suspension stream while steering it into the trough channel inlet (9).