Curtain Applicator Gap Control for Stable Starch Coating Modes
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Solution Overview
Problem
Existing coating technologies for packaging papers and cardboard, particularly those using recycled fibers, face challenges in achieving optimal starch penetration and application efficiency, leading to compromised paper quality and increased energy consumption, especially when transitioning between different coating methods like film and sump presses.
Innovation Solution
A device combining a curtain applicator with adjustable gap settings allows operation as both a film press and a sump press, enabling flexible application of coating media with high solids content, thereby stabilizing the coating process and improving paper quality without requiring machine shutdowns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a curtain sizer is used to apply starch with high solids content (above 10%), then the application weight and penetration can be improved, but the liquid film becomes unstable at low viscosities (below 30 mPa·s), disrupting uniform distribution
Solution Approach 1:
The patent makes the nozzle gap adjustable to dynamically adapt to different starch viscosities. When viscosity is low, the gap is increased to maintain film stability; when viscosity is high, the gap is decreased to achieve proper application weight. This dynamic adjustment resolves the contradiction between maintaining film stability and achieving high application weight.
Solution Approach 2:
The patent changes the physical parameter of the nozzle gap size based on starch viscosity conditions. By adjusting this parameter, the system can handle both low-viscosity starch (with larger gap for stability) and high-viscosity starch (with smaller gap for proper application), resolving the stability versus application weight contradiction.
2Manufacturing precision
If a bottom press with hard roller coverings is used to achieve high starch penetration, then penetration depth is improved, but energy consumption increases due to high line forces (80-100 kN/m)
Solution Approach 1:
The patent replaces the high-mechanical-force bottom press system with a curtain sizer system that uses minimal line forces (0-2 kN/m). The starch is applied via a liquid curtain that is gently received by the paper web, eliminating the need for high compression forces while still achieving effective starch application and penetration.
Solution Approach 2:
The patent changes the operating parameter from high line force (80-100 kN/m in bottom presses) to near-zero line force (0-2 kN/m in curtain sizer). This parameter change dramatically reduces energy consumption while maintaining effective starch penetration through the liquid curtain application method.
3Use of energy by moving object
If a film press is used to apply starch, then energy consumption is reduced compared to sump presses, but the starch solids content is limited to below 10%
Solution Approach 1:
The patent creates a curtain sizer system that combines the low energy consumption of film presses with the high solids content capability of sump presses. By using a adjustable-gap nozzle that can operate in both film mode (for low viscosity) and sump mode (for high viscosity), the system achieves multi-functionality, breaking the trade-off between energy consumption and solids content.
4Manufacturing precision
If the nozzle gap is kept small for precise application, then application precision is improved, but the liquid curtain becomes unstable at low starch viscosities
Solution Approach 1:
The patent makes the nozzle gap dynamically adjustable rather than fixed. For low-viscosity starch, the gap is increased to maintain curtain stability; for high-viscosity starch, the gap is decreased to achieve precise application. This dynamic adaptation resolves the contradiction between precision and stability.
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 device enhances paper quality by allowing seamless transitions between coating modes, reducing energy consumption, and maintaining uniform application regardless of starch viscosity and solids content, thus optimizing production efficiency.
Implementation Method 1
The curtain applicator nozzle (14) is designed to apply the coating medium in the form of a liquid curtain (4.1, 4.2) onto the applicator roller (6, 7)
Implementation Method 2
a liquid curtain (4.1, 4.2) becomes unstable upon contact with the application roller, disrupting the uniform distribution
Implementation Method 3
Capillary forces during the residence time in the sump and the hydraulic pressure during passage through the nip allow the applicator to penetrate the web
Implementation Method 4
The line forces between the application rollers vary between 40 and 100 kN/m
Implementation Method 5
The starch or sizing penetrates the paper while the paper web is guided through the slurry and the nip
Implementation Method 6
Capillary forces during the residence time in the sump and the hydraulic pressure during passage through the nip allow the applicator to penetrate the web
Data Source
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AI summary
Device for applying coating media, in particular starch or glue, to a moving paper and cardboard web (11), in particular testliner or corrugated board, by means of at least one curtain applicator (2.1, 2.2) with a curtain applicator nozzle for applying the coating medium to an applicator roller (6, 7), which forms a treatment nip (15) with a second roller (6, 7), in which the coating medium is transferred from the applicator roller (6, 7) to the respective side of the paper and cardboard web (11), and the curtain applicator nozzle has a gap adjustment (3.1, 3.2) for adjusting the exit gap (14.1, 14.2), wherein differently prepared coating media can be fed to the at least one curtain applicator nozzle, and a gap adjustment (3.1, 3.2) of the exit gap (14.1, 14.2) of the curtain applicator nozzle from 100 µm to 500 µm for a film operation and on 500 µm to 2.0 mm for a swamp operation that includes at least one curtain application unit (2.1, 2.2) capable of operating in these different modes of operation.