Vacuum Control in Paper Machine Forming Section Suction Boxes
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Solution Overview
Problem
Existing methods for controlling vacuum in forming sections of fiber web production machines are complex, cumbersome, and inefficient, leading to suboptimal water removal and increased energy consumption.
Innovation Solution
A method and system for controlling vacuum in forming sections by uniformly increasing the vacuum set points of successive suction boxes, with the last suction box's set point value independently set, and preceding set points calculated based on the following suction box's value, optimizing water removal efficiency and energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If same vacuum is used in several successive suction boxes, then effectiveness of the first suction box is good, but water removal efficiency in following suction boxes decreases significantly while energy consumption remains about the same
Solution Approach 1:
The patent applies parameter changes by progressively increasing the vacuum level (negative pressure) in each successive suction box along the fiber web production line. Instead of using the same vacuum level in all suction boxes, the system varies the vacuum parameter to match the increasing dewatering difficulty as water is removed from the fiber suspension. This ensures each suction box operates at optimal vacuum for its specific position, improving overall water removal efficiency while avoiding excessive energy consumption in later stages.
2Productivity
If vacuum is increased to achieve corresponding water removal efficiency, then water removal capacity is improved, but energy consumption is highly increased
Solution Approach 1:
The patent applies local quality by tailoring the vacuum level to each specific suction box location along the forming section. Earlier suction boxes use lower vacuum levels when the fiber suspension contains more water, while later suction boxes use progressively higher vacuum levels as the suspension becomes more concentrated. This localized optimization ensures each suction box uses only the necessary energy for its specific dewatering task, avoiding the excessive energy consumption that would result from applying high vacuum throughout the entire line.
3Manufacturing precision
If highly refined stock and high fines content are used to achieve required product grade, then desired web quality is achieved, but dewatering properties of the stock suspension decrease
Solution Approach 1:
The patent applies dynamics by implementing a progressive vacuum increase strategy that adapts to the changing dewatering characteristics of the fiber suspension as it moves through the forming section. Highly refined stocks with high fines content create increasing web sealing effects that progressively resist water removal. The system dynamically adjusts vacuum levels in successive suction boxes to overcome this progressive resistance, maintaining effective dewatering throughout the process while preserving the required web quality achieved through high fiber refinement.
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 approach achieves an optimal, uniformly increasing vacuum profile, reducing manual operations, minimizing human error, and improving the quality and runnability of the fiber web production process, while also decreasing energy consumption and extending the lifespan of forming section components.
Implementation Method 1
controlling vacuum in a forming section (200)... water is removed on the forming section through a forming wire or forming wires... vacuum can be used only to limited extent
Data Source
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AI summary
The invention relates to a method for controlling vacuum in a forming section (200) comprising at least one forming unit (250), which forming unit (250) comprises at least one fourdrinier wire (10) and an arrangement of several successive suction boxes (15A-15E) with controllable vacuum at the fourdrinier wire (10). The method comprises steps of setting of vacuum set point value of last suction box (15E) of the several successive suction boxes (15A-15E) with controllable vacuum in running direction (S; S1) of the forming unit (250), and calculating set point value of at least one successive suction boxes (15A-15D) with controllable vacuum preceding the last suction box (15E) from set point value of the following suction box based on the vacuum set point value of the last suction box (15E) such, that the set point value of the vacuum (Pi) of the preceding suction box in the running direction (S; S1) of the forming unit (250) is smaller than the set point value of the vacuum (Pi+1 ) of the following suction box in the running direction (S; S1) of the forming unit (250). The invention also relates to a forming section with a control system (100) for controlling vacuum in the forming section (200).