Paper Machine Showers Using CO2-Treated Water Against Scale
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Solution Overview
Problem
Existing methods fail to effectively prevent and eliminate scale deposition in the machine clothing and showers of a paper machine's press and forming sections, particularly due to the use of recycled furnish and additives that increase contamination, leading to scaling issues and inefficiencies in cleaning and lubrication processes.
Innovation Solution
The method involves using chemically treated fresh water with a pH between 7 and 9 and adding CO2 to maintain the Langelier Saturation Index (LSI) between -1.0 ± 0.2 ≤ LSI < 0 ± 0.2, which is fed to high-pressure and low-pressure showers to control scaling and enhance the effectiveness of oxidizing antimicrobials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional water treatment methods are used in paper machines, then basic cleaning function is provided, but scale deposition occurs on machine clothing and showers
Solution Approach 1:
The patent applies parameter changes by adjusting the Langelier Saturation Index (LSI) to a specific range of -3.0 to -0.5 through chemical treatment of process water. This parameter modification transforms the water's scaling tendency from positive (scale-forming) to negative (scale-preventing), directly resolving the contradiction between maintaining cleaning function and preventing scale deposition on machine clothing and showers
Solution Approach 2:
The patent introduces an intermediary chemical treatment process that modifies the water's properties before it contacts the machine clothing and showers. By using chemical agents to adjust pH and LSI, the water becomes an intermediary medium that cleans effectively without causing scale deposition, thus resolving the contradiction between cleaning effectiveness and scale prevention
2Manufacturing precision
If recycled furnish and additives are used to meet quality requirements, then sheet quality improves, but contamination and scaling problems increase
Solution Approach 1:
The patent converts the harmful effect of recycled furnish and additives (which cause scaling) into a beneficial outcome by chemically treating the process water to prevent scale formation. The same water that contains contaminants from recycled fiber is treated to have negative LSI, transforming it from a scale-causing medium to a scale-preventing cleaning medium, thus allowing continued use of recycled furnish while eliminating scaling problems
3Reliability
If water is heated for showering to improve cleaning, then cleaning effectiveness increases, but scale deposition is promoted
Solution Approach 1:
The patent applies parameter changes by decoupling the relationship between temperature and scaling. Instead of using high temperature to prevent scaling, the patent chemically treats the water to achieve negative LSI at the actual operating temperature. This parameter modification allows the water to remain at optimal cleaning temperature while the chemical treatment prevents scale deposition, resolving the contradiction between cleaning effectiveness and scale prevention
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 effectively prevents scale deposition, reduces water consumption, and enhances the efficacy of antimicrobials by maintaining optimal LSI conditions, thereby improving fabric efficiency and reducing maintenance needs.
Implementation Method 1
adding CO2 to said water in an amount between 5 and 1000 mg/L of water which is suitable to maintain the Langelier saturation index between -1.0 ± 0.2 ≤ LSI < 0 ± 0.2
Implementation Method 2
maintain the Langelier saturation index between -1.0 ± 0.2 ≤ LSI < 0 ± 0.2, which is fed to high-pressure and low-pressure showers to control scaling
Implementation Method 3
Providing fresh water with a pH between 7 and 9 and heated between 40 and 55°C
Implementation Method 4
fed to high-pressure and low-pressure showers to control scaling and enhance the effectiveness of oxidizing antimicrobials
Data Source
AI summary
The present application a method to prevent and/or eliminate the deposition of scale in the machine clothing and showers of a paper machine's press section and/or forming section. The method comprises adding CO2 into the water that is used in the paper machine's press section and/or forming section. Advantageously, the method also allows to optimize the use of oxidizing antimicrobials.