Microfibrillated Cellulose Drying via Cold Gas Sublimation
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Solution Overview
Problem
Current methods for drying microfibrillated cellulose, such as freeze-drying with liquid nitrogen, are costly and inefficient for commercial-scale production due to high energy requirements and contamination issues with cryoprotectants, while conventional drying methods damage the microfibrillated structure.
Innovation Solution
A method involving applying a composition of microfibrillated cellulose and liquid onto a cold surface, freezing, and then drying using a cold moving gas stream, which maintains the structural integrity and allows for efficient energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional drying methods are used, then drying efficiency is improved, but the microfibrillated structure is damaged
Solution Approach 1:
The invention utilizes phase transition of water from liquid to solid (freezing) and then from solid to vapor (sublimation) to dry the microfibrillated cellulose. The composition is frozen at temperatures below 0°C to form ice, which is then sublimated in a vacuum environment, allowing efficient drying without thermal damage to the microfibrillated structure.
2Stability of the object's composition
If freeze-drying with liquid nitrogen is used, then the microfibrillated structure is preserved, but energy consumption and cost increase
Solution Approach 1:
The invention changes the temperature parameter from extreme cryogenic temperatures (liquid nitrogen at -196°C) to milder sub-zero temperatures (above -50°C, preferably above -20°C). This parameter change maintains the preservative effect on the microfibrillated structure while significantly reducing energy consumption and operational costs.
Solution Approach 2:
The invention replaces expensive liquid nitrogen with ordinary cooling agents or refrigeration systems that can achieve sub-zero temperatures without requiring cryogenic liquids. This substitution uses cheaper, more accessible resources to achieve the same freezing effect.
3Stability of the object's composition
If freeze-drying with liquid nitrogen is used, then the microfibrillated structure is preserved, but contamination with cryoprotectants occurs
Solution Approach 1:
The invention extracts or removes the need for cryoprotectants from the freezing process by using controlled freezing at milder temperatures. This elimination of cryoprotectants prevents contamination of the microfibrillated cellulose while still achieving structure preservation through controlled phase transition.
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 method effectively preserves the microfibrillated structure, enabling cost-effective and efficient drying of microfibrillated cellulose on a commercial scale while maintaining its properties for reconstitution.
Implementation Method 1
applying a composition comprising microfibrillated cellulose and at least one liquid onto a surface that is sufficiently cold to at least partially freeze said composition
Implementation Method 2
drying frozen particles formed in step (ii) or in step (iii) comprising: subjecting said particles to a cold moving gas stream
Data Source
AI summary
The invention relates to a method for drying microfibrillated cellulose, comprising at least the following steps: (i) applying a composition comprising microfibrillated cellulose and a liquid onto a cold surface; (H) removing the frozen composition formed in step (i) from said surface to form frozen particles; (iii) optionally increasing the size of the frozen particles formed in step (ii); (iv) drying the frozen particles formed in step (iii) comprising: subjecting said particles to a cold moving gas thus removing liquid by means comprising sublimation and optionally (v) isolating the microfibrillated cellulose formed in step (iv). The invention also relates to a device for carrying out the method of the invention.