Continuous Pressing for Micro Fibrillated Cellulose Dewatering
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Solution Overview
Problem
Current methods for producing micro fibrillated cellulose (MFC) face challenges such as high energy consumption, lengthy drying times, and transportation costs due to batch-type drying processes like evaporation and freezing, which also risk hornification and result in low consistency levels.
Innovation Solution
Implementing continuous pressing technologies like screw press, twin wire press, and twin roll press to dry MFC suspensions from 0.5-5% consistency to 6-60%, with on-line/off-line measurement and control systems to adjust pressing parameters for optimal consistency and fines content, allowing for high consistency, low energy use, and efficient production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If batch-type drying processes (evaporation or freezing) are used to dry MFC suspension, then the MFC can be dried to high consistency, but energy consumption increases significantly and drying time becomes very long
Solution Approach 1:
The patent replaces thermal evaporation and freezing processes with mechanical pressing to achieve dewatering. The mechanical press applies direct mechanical force to compress the MFC suspension, extracting water through pressure rather than using thermal energy for phase change, thereby significantly reducing energy consumption while maintaining high drying speed
Solution Approach 2:
The patent changes the drying parameter from thermal parameters (temperature, phase change) to mechanical parameters (pressure, compression force). By controlling pressing pressure and duration, the system achieves efficient dewatering without the high energy costs associated with evaporation and freezing processes
2Productivity
If batch-type drying processes are used, then MFC can be dried, but the process becomes very time consuming
Solution Approach 1:
The patent implements a continuous pressing process where MFC suspension is continuously fed into the mechanical press, dewatered in real-time, and discharged as high-consistency product. This eliminates the batch processing cycles of loading, drying, and unloading, maintaining continuous operation that dramatically reduces total drying time and increases production rate
3Quantity of substance
If high consistency MFC suspension is produced, then transportation costs are reduced and further drying is avoided, but achieving high consistency through conventional methods requires excessive energy
Solution Approach 1:
The patent uses mechanical pressing instead of thermal evaporation to achieve high consistency MFC suspension. The mechanical press directly compresses the suspension to remove water, achieving 6-60% consistency without the energy-intensive phase change processes, making high consistency production energy-efficient
4Productivity
If MFC suspension is dried by evaporation or freezing, then drying can be achieved, but hornification may occur which destroys MFC quality
Solution Approach 1:
The patent replaces thermal drying methods with mechanical pressing to avoid hornification. By using mechanical force instead of heat, the cell wall structure of MFC is preserved without the chemical and physical changes caused by high-temperature evaporation or freezing, maintaining MFC quality while achieving efficient dewatering
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 reduces energy consumption, accelerates drying, enhances production rates, and maintains fines quality, enabling economic transportation and precise consistency control, while minimizing fines loss by recycling filtrate back into processing stages.
Implementation Method 1
dried by continuous pressing to a consistency of 6-60%
Data Source
AI summary
The invention relates to a system of producing MFC (micro fibrillated cellulose) having a process device (30) of a pulper, a refiner or a screen configured to process MFC suspension to consistency of 0.5-5%. The system has a continuous pressing means (15; 25, 26) configured to dry the MFC suspension to a consistency of 6-60%. A method of producing MFC has at least one process stage (30) which processes a MFC suspension to a consistency of 0.5-5% by a process device (30). In the process stage the MFC suspension is pulped in a pulping stage in a pulper and/or refined in a refining stage by a refiner and/or screened in a screening stage by a screen. The MFC suspension having the consistency of 0.5-5% is dried in a drying stage of continuous pressing (15, 25, 26) by continuous a pressing device (15, 25, 26) to a consistency of 6-60%.