Lignin Dewatering via Critical Temperature Phase Transition
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Solution Overview
Problem
Current methods for reducing water content in lignin solids from paper industry spent pulping liquor are energy-intensive, making it costly to use these solids as fuel for generating power and steam, as they require substantial energy for drying, which offsets the energy gained from combustion.
Innovation Solution
Heating lignin solids to a critical temperature above 180°F causes them to agglomerate into lower moisture granular solids, allowing excess water to be decanted and recycled, reducing the moisture content to 45-55%, which can be further reduced with thermal drying if needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thermal drying equipment is used to reduce water content in lignin solids, then moisture content is reduced, but energy consumption increases substantially
Solution Approach 1:
The patent applies phase transition by heating lignin solids to a critical temperature (above 180°F) where the lignin undergoes a phase change from a hydrated gel state to a dehydrated granular state. This thermal phase transition causes bound water to be released and the lignin structure to collapse into a lower moisture content form, enabling dewatering without substantial energy input compared to conventional drying
Solution Approach 2:
The patent changes the temperature parameter to a specific critical range (above 180°F) to induce the phase transition in lignin. By controlling the temperature parameter within this critical range, the lignin structure transforms and releases bound water, achieving effective dewatering while minimizing energy consumption compared to high-temperature drying processes
2Quantity of substance
If mechanical separation by pressure is used to reduce moisture, then water content is reduced to about 65 percent, but additional thermal drying energy is still required
Solution Approach 1:
The patent uses phase transition at the critical temperature to achieve a more effective dewatering than mechanical pressure alone. The phase change causes the lignin to expel bound water and restructure into a granular form with inherently lower moisture content, eliminating or reducing the need for subsequent thermal drying that would otherwise be required after mechanical separation
3Productivity
If lignin solids with high water content are used as fuel, then combustion can occur, but thermal efficiency is reduced
Solution Approach 1:
By applying the phase transition method at critical temperature, the lignin solids are transformed into a dehydrated granular state with significantly reduced moisture content. This produces a fuel material with higher thermal efficiency and combustion quality, converting the lignin into a more energy-dense form suitable for efficient power and steam generation
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 reduces the water content of lignin solids in a single step, significantly lowering energy consumption and enabling more efficient use as a fuel source by separating lignin solids from water through gravity settling, with the potential for 80% of water to be recycled.
Implementation Method 1
When the lignin mass being heated during the treatment process reaches the critical temperature for separation, lignin solids precipitate as the mass is subsequently cooled
Implementation Method 2
The density difference between the water and the newly-formed solids allows gravity to cause the lignin solids to settle below the aqueous phase
Data Source
AI summary
A lignin plastics solids mass containing lignin solids and liquids with up to 85% liquids can be partially dewatered by heating the lignin plastics solids mass to above a critical temperature at which time the lignin plastics solids agglomerate into lower moisture granular solids with between about 45% to 55% liquids releasing excess liquid which can be easily removed from the solids. The process is particularly useful for lignin plastics solids removed from black liquor from paper mills, or for similar lignin plastics solids masses, which can contain up to 85% liquids and which need to be dried to form useful lignin solids, which can be used for example for fuel. The dewatering process can be combined with the process for separating the lignin from the black liquor to separate the dewatered lignin directly from the black liquor.