Microfibrillated Cellulose Dewatering via Multi-Stage Pressure
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Solution Overview
Problem
Current methods for dewatering microfibrillated cellulose slurries are inefficient due to high energy consumption, hornification issues, and difficulty in applying mechanical pressure without fiber loss, especially when the slurry forms a gel and clogs equipment.
Innovation Solution
A process involving multiple stages of increasing mechanical pressure applied through methods like double wire dewatering equipment, wedge gaps, and rolls to efficiently remove water from microfibrillated cellulose slurries without causing hornification, allowing for high dry content achievement while maintaining fiber properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If drying techniques (evaporation, sublimation, spray drying, freeze drying) are used to remove water from microfibrillated cellulose slurry, then water content is reduced, but energy consumption increases significantly and hornification occurs
Solution Approach 1:
The patent replaces thermal drying methods with mechanical dewatering methods. Specifically, it uses a press with a frame, press plate, and filter paper to apply mechanical pressure for water removal, substituting the thermal energy-based evaporation and sublimation processes with a mechanical compression system that consumes less energy
Solution Approach 2:
The patent introduces filter paper as an intermediary medium between the microfibrillated cellulose slurry and the press plate. The filter paper facilitates water removal while preventing direct contact between the press and cellulose fibers, thereby avoiding hornification while enabling efficient mechanical dewatering
2Quantity of substance
If drying techniques are used to remove water from microfibrillated cellulose slurry, then water content is reduced, but hornification occurs causing irreversible fiber bonding
Solution Approach 1:
The patent introduces filter paper as an intermediary medium between the microfibrillated cellulose slurry and the press plate. The filter paper facilitates water removal while preventing direct contact between the press and cellulose fibers, thereby avoiding hornification while enabling efficient mechanical dewatering
Solution Approach 2:
The patent replaces thermal drying methods with mechanical dewatering methods. Specifically, it uses a press with a frame, press plate, and filter paper to apply mechanical pressure for water removal, substituting the thermal energy-based evaporation and sublimation processes with a mechanical compression system that consumes less energy
3Quantity of substance
If mechanical pressure is applied to dewater microfibrillated cellulose slurry, then water is removed, but the gel escapes through openings and microfibrillated cellulose clogs the wire
Solution Approach 1:
The patent introduces filter paper as an intermediary medium between the microfibrillated cellulose slurry and the press plate. The filter paper facilitates water removal while preventing direct contact between the press and cellulose fibers, thereby avoiding hornification while enabling efficient mechanical dewatering
Solution Approach 2:
The patent uses filter paper as a flexible thin film that allows water to pass through while retaining the microfibrillated cellulose. The filter paper's porous structure enables selective permeability, letting liquid water escape while blocking the gel and cellulose particles, thus preventing both gel escape and fiber clogging
4Quantity of substance
If filtration is used to remove water from microfibrillated cellulose slurry, then water can be removed, but excessively high pressures and long filtration times are required
Solution Approach 1:
The patent introduces filter paper as an intermediary medium between the microfibrillated cellulose slurry and the press plate. The filter paper facilitates water removal while preventing direct contact between the press and cellulose fibers, thereby avoiding hornification while enabling efficient mechanical dewatering
Solution Approach 2:
The patent merges the filtration function and pressing function into a single integrated operation. The filter paper is placed within the pressing apparatus, combining the separating action of filtration with the compressing action of pressing, thereby achieving efficient water removal without requiring excessively high pressures or long times
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 process effectively increases the dry content of microfibrillated cellulose slurries to 50% by weight, preventing hornification and maintaining fiber properties for use in applications like strength additives and thickeners, while being energy-efficient and avoiding fiber loss.
Implementation Method 1
subjecting the slurry to mechanical pressure in order to dewater the slurry
Implementation Method 2
Filtration is a method that also can be used. However it is very difficult to remove water from a slurry comprising MFC by filtration due to the dense web formed by the slurry
Data Source
AI summary
The present invention relates to a process for dewatering a slurry comprising a microfibrillated cellulose wherein the process comprises the following steps of providing a slurry comprising a microfibrillated cellulose and a liquid, subjecting the slurry to a first mechanical pressure in order to dewater the slurry, and subjecting the slurry to a second mechanical pressure which second pressure is higher than the first pressure.