Continuous Cellulose Pulp Production via Electrolytic Chemical Regeneration
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Solution Overview
Problem
Conventional cellulose pulp manufacturing processes consume high energy and water, use harsh chemicals, and result in environmental pollution, failing to produce high whiteness cellulose pulp with minimal lignin content efficiently from grass-like feedstocks.
Innovation Solution
A continuous process using mild digestion and bleaching conditions with a hydrogen peroxide-based system without sodium hydroxide, optimized concentrations of sodium hydroxide and sodium chloride, and integrated electrolytic regeneration of chemicals to minimize mechanical stress and chemical usage, achieving high whiteness and low lignin content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional sulphur-based chemicals are used for digestion and bleaching, then lignin removal efficiency is improved, but environmental pollution and harmful chemical residues increase
Solution Approach 1:
The patent changes the chemical parameters by replacing sulphur-based chemicals with a sodium hydroxide-hydrogen peroxide system, operating at milder temperatures (70-120°C for digestion, 70-100°C for bleaching) and achieving high whiteness (>90%) without sulphur pollution
Solution Approach 2:
The patent converts the harmful black liquor containing lignin and chemicals into a beneficial regenerated white liquor through electrolysis, where lignin is removed at the anode and sodium hydroxide is regenerated at the cathode for reuse in digestion
2Productivity
If intensive mechanical disperging is used to process pulp suspension, then cellulose fiber separation is improved, but energy consumption and fiber damage increase
Solution Approach 1:
The patent replaces intensive mechanical disperging with a chemical-based approach using optimized sodium hydroxide and hydrogen peroxide treatments that naturally separate and preserve cellulose fibers without high-energy mechanical intervention
3Productivity
If harsh digestion conditions are used to remove lignin, then lignin removal efficiency is improved, but cellulose fiber preservation deteriorates
Solution Approach 1:
The patent optimizes digestion parameters using mild sodium hydroxide concentrations (0.50-2.00% w/w) at temperatures of 70-120°C, which selectively removes lignin while preserving the structure and integrity of cellulose fibers for high-quality paper production
4Productivity
If conventional bleaching systems with sodium hydroxide are used, then bleaching efficiency is improved, but chemical consumption and environmental impact increase
Solution Approach 1:
The patent changes the bleaching chemical system from conventional sodium hydroxide-based processes to a hydrogen peroxide-based system (20-40% w/w H2O2 with 30-45% w/w sodium silicate) operating at 70-100°C, achieving whiteness >90% with reduced chemical consumption and environmental impact
Solution Approach 2:
The patent uses sodium silicate as an intermediary stabilizer that enhances the effectiveness of hydrogen peroxide bleaching, allowing reduced chemical concentrations while maintaining high bleaching efficiency and fiber preservation
5Manufacturing precision
If high water consumption is used in conventional processes, then chemical washing and purification are improved, but water efficiency deteriorates
Solution Approach 1:
The patent recovers and regenerates process chemicals from the black liquor through electrolysis, converting spent sodium hydroxide solution back into usable white liquor for reuse in digestion, thereby minimizing water consumption and chemical waste
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
The process achieves cellulose pulp with whiteness greater than 90% and lignin content less than 5% while reducing energy and water consumption, preserving natural fibers, and closing the chemical cycle to minimize environmental impact.
Implementation Method 1
a dissolution of non-cellulosic substances from the grass-like plant feedstock occurs during the mass transfer from one to the other side of the said longitudinal digester
Implementation Method 2
a novel hydrogen peroxide (H2O2)-based bleaching system
Implementation Method 3
the black liquor is subjected to electrolysis with direct electric current (DC) between two electrodes
Data Source
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AI summary
The present invention discloses the continuous process for production of cellulose pulp of very high whiteness from grass-like plant feedstock suitable for paper making. Process comprising the steps of: preparing the grass-like plant feedstock by comminuting; dedusting; continuous digestion with optimized concentrations of NaOH and NaCl; disperging; continuous bleaching with optimized concentrations of H2O2 and sodium silicate without the use of NaOH; optional disperging; dewatering to remove the black liquor; and washing, to yield final cellulose pulp of very high whiteness, >90%, suitable for manufacturing of paper or cellulose sheets. The process additionally includes integrated electrolytic removal of lignin and other by-products accompanied with regeneration of cooking chemicals solution, what enables completely closed process materials cycle. In one form of invention, heating of digesting and bleaching steps can be optionally performed by microwave (MW) heating. The preferred grass-like feedstock for the process is miscanthus (Miscanthus x giganteus, Andersson).