Surfactant Removal via Dispersed Air Flotation in Papermaking
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Solution Overview
Problem
The presence of surfactants in papermaking waters leads to air stabilization and foam formation in head circuits, reduces the effectiveness of chemical products, and affects paper quality and productivity, necessitating effective elimination.
Innovation Solution
Implementing a dispersed air flotation process to separate surfactants from papermaking waters, with the treatment being conducted on filtration waters or fiber recuperator waters to minimize solid and water losses, and utilizing ozone treatment for surfactant degradation in the resulting flotation foam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If surfactants are present in papermaking waters, then wetting properties of water are improved, but air stabilization and foam formation occur in head circuits
Solution Approach 1:
The invention extracts and removes surfactants from the papermaking water system using a flotation cell. The flotation process separates surfactants from the water phase by forming a foam fraction that can be removed, thereby eliminating the harmful effects of surfactants while maintaining water quality for papermaking operations.
Solution Approach 2:
The invention converts the harmful presence of surfactants into a beneficial separation process. By introducing air bubbles into the surfactant-containing water, the surfactants are selectively concentrated at the air-water interface and removed as foam, transforming a problematic substance into a separable phase that can be easily eliminated from the system.
2Object-affected harmful factors
If deaerator devices are added to remove air from head circuits, then air stabilization is reduced, but device complexity increases
Solution Approach 1:
The flotation cell extracts and removes surfactants from the papermaking water before the water is reused in the head circuits. By removing the surfactants that cause air stabilization, the need for additional deaerator devices is eliminated, simplifying the overall system while still addressing the air in paste problem.
Solution Approach 2:
The invention performs preliminary removal of surfactants from the white water before it is recirculated to the head circuits. This preliminary action prevents the formation of air-stabilized bubbles in the first place, rather than requiring subsequent deaeration equipment to remove air that has already been stabilized by surfactants.
3Object-generated harmful factors
If anti-foaming agents are added to suppress foam, then foam formation is reduced, but chemical product usage increases
Solution Approach 1:
The flotation cell directly removes surfactants from the papermaking water through foam fractionation. By extracting the surfactants that cause foam formation, the need for anti-foaming agents is eliminated, reducing chemical consumption while still effectively controlling foam in the head circuits.
Solution Approach 2:
The invention performs preliminary removal of surfactants from white water before recirculation, preventing foam formation at its source. This preliminary action eliminates the need for continuous addition of anti-foaming agents throughout the papermaking process, reducing both chemical usage and operational complexity.
4Quantity of substance
If surfactants remain in process water, then water retention is maintained, but effectiveness of chemical products is reduced
Solution Approach 1:
The flotation cell extracts and removes surfactants from the papermaking water system. By eliminating surfactants that interfere with chemical product performance, the effectiveness of sizing agents, retention aids, and other chemicals is restored and maintained, while water retention in the system is preserved through controlled recirculation.
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 eliminates surfactants, improves paper machine operation, reduces chemical product usage, and minimizes defects like air in the pulp, enhancing paper quality and productivity while reducing water and solid losses.
Implementation Method 1
separating the surface-active substances from the water which contains them, by bringing them to the surface by insufflation, within the liquid mass, of air bubbles
Implementation Method 2
the flotation foam is treated beforehand with ozone, which facilitates the degradation of the surfactants
Data Source
Figure 1
AI summary
The process for fabricating a paper (2) on a machine, comprises separating surface-active agents through dispersed air (9) flotation in a wet part, and eliminating flotation foam containing the surface-active agents. The separation of the agents is carried out on all or part of filtration water from the paper formation and on all or part of clear water from a fiber recuperator. Recycled or mechanical slurry is used in the process. The flotation foam is treated with ozone and then evacuated in a purification station and a drainage table. An independent claim is included for a machine with paper.