Shoe Press Roll Arrangement for High-Speed Paper Dewatering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-speed dewatering of paper or cardboard webs with increased impurities leads to contamination and high re-moistening costs, particularly when using smooth surfaces and open transfer processes.
Innovation Solution
The press arrangement employs extended press gaps with shoe and suctioned press rolls, coupled with vacuum assistance and steam application, along with water-absorbing belts and transfer belts to manage moisture and adhesion effectively, ensuring safe web guidance and reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate dewatering belts are used in press nips, then web guidance is improved, but costs increase and remoistening increases
Solution Approach 1:
The patent merges the functions of two separate dewatering belts into a single dewatering belt system. The single belt performs both the dewatering function and the web guidance function that previously required two separate belts, thereby reducing costs while maintaining reliable web guidance through the press nips.
2Device complexity
If one dewatering belt is used through the second press nip, then costs are reduced, but remoistening increases and web guidance becomes problematic
Solution Approach 1:
The single dewatering belt is designed to extend through both press nips, merging the dewatering and web support functions into one continuous element. This eliminates the need for complex transfer mechanisms while maintaining stable web guidance and reducing remoistening through continuous support.
Solution Approach 2:
The single dewatering belt acts as an intermediary element that bridges both press nips, providing continuous support to the web and enabling smooth transition through the pressing zones without direct contact between the web and press roll surfaces that would cause adhesion and remoistening.
3Productivity
If open transfer process is used at high machine speeds, then productivity is improved, but web guidance and transfer reliability become problematic
Solution Approach 1:
The single dewatering belt provides continuous support to the web through both press nips without interruption or transfer, enabling stable web guidance at high machine speeds. The continuous action of the belt through the entire pressing zone eliminates the transfer complexities that would compromise reliability at high speeds.
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 enables high dry content retention with improved web guidance and reduced re-moistening, maintaining low operational costs while minimizing contamination and transfer complexities at high machine speeds.
Implementation Method 1
a first extended press nip formed by a lower shoe press roll (2) and an upper, vacuumed press roll (3)
Implementation Method 2
at least one endlessly circulating, water-absorbing dewatering belt (7, 9)
Implementation Method 3
the fibrous web (1) adheres to the smooth surface of the corresponding press roll
Data Source
Figure 1~2
AI summary
The invention relates to a pressing arrangement for dewatering a paper or cardboard web (1) with a weight per unit area of between 60 and 250 g/m2 and at a machine speed of up to 1800 m/min, consisting of four pressing rollers (2, 3, 4, 5) for the formation of three pressure nips, through which the web (1) runs together with in each case at least one endlessly circulating, water-absorbing dewatering belt (6, 7, 9). Here, high drynesses with secure web guidance and costs which are as low as possible are to be made possible by virtue of the fact that the first and the third pressure nip are of extended configuration in each case via the interaction of a shoe pressing roller (2, 5) with a cylindrical pressing roller (3, 4), and the first shoe pressing roller (2) is arranged below the web (1) and the second shoe pressing roller (5) is arranged above the web (1).