Continuous Grass Pulp Digestion Without Stirring
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Solution Overview
Problem
Conventional cellulose pulp manufacturing processes consume high energy and use sulfur-based chemicals, leading to environmental impact and mechanical stress that damages natural fibers, while seeking to produce pulp from grass-like feedstocks with minimal processing and low chemical usage.
Innovation Solution
A continuous process using mild digestion conditions (70-100 °C with 0.9-1.5 w/w NaOH and 0.15-0.4% w/w NaCl or Na2SO3) in a digester without stirring, achieving high concentration of suspension, low energy consumption, and minimal mechanical stress to preserve natural fibers, with optional sulphur-free digestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional sulphur-based chemicals are used for digestion, then effective removal of noncellulosic fraction is achieved, but environmental impact increases and high energy consumption is required
Solution Approach 1:
The patent changes the chemical parameters by using sulphur-free digestion chemicals (sodium hydroxide and sodium carbonate) instead of conventional sulphur-based chemicals. This substitution maintains effective removal of noncellulosic fraction while eliminating environmental harm associated with sulphur compounds, directly resolving the contradiction between effectiveness and environmental impact
Solution Approach 2:
The patent employs readily available, inexpensive alkaline chemicals (sodium hydroxide and sodium carbonate) that can be easily disposed of or neutralized, replacing costly and environmentally persistent sulphur-based chemicals. This approach reduces both environmental impact and operational costs while maintaining digestion effectiveness
2Manufacturing precision
If intensive milling is performed to achieve suitable product after using milder chemicals, then paper manufacturing quality is improved, but energy consumption increases significantly
Solution Approach 1:
The patent performs preliminary action by conducting effective digestion with alkaline chemicals before milling, which pre-softens and separates the cellulose fibers from lignin and hemicellulose. This preliminary chemical treatment reduces the mechanical energy required for subsequent milling while maintaining product quality, resolving the contradiction between manufacturing precision and energy consumption
Solution Approach 2:
The patent substitutes mechanical action with chemical action by using alkaline digestion to achieve fiber separation and purification. Instead of relying on intensive mechanical milling to achieve the desired product quality, the chemical digestion process accomplishes the separation function, thereby reducing energy consumption while maintaining manufacturing precision
3Stability of the object's composition
If complex mechanical processing is applied to preserve natural fibers, then fiber quality is maintained, but equipment complexity and investment increase
Solution Approach 1:
The patent replaces complex mechanical processing systems with a simple chemical digestion system using alkaline solutions. This substitution preserves natural cellulose fibers through chemical action rather than mechanical stress, thereby maintaining fiber quality while significantly reducing equipment complexity and investment requirements
Solution Approach 2:
The patent employs a self-service approach where the alkaline digestion chemicals automatically perform the fiber preservation function without requiring complex mechanical intervention. The chemical process naturally protects and separates fibers during digestion, eliminating the need for additional mechanical protection devices and reducing overall system complexity
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 results in eco-friendly, high-output cellulose pulp production with significantly reduced energy and chemical usage, preserving natural fibers and minimizing environmental impact, while using simplified equipment and lower water consumption.
Implementation Method 1
continuous digestion of a grass-like dust-free plant feedstock in a digester formed as a vertical column internally having only smooth side walls; where grass-like plant feedstock is continuously fed directly on the top of the said digester via conveyor. In parallel with said dust-free feedstock top-feeding, chemicals for digestion selected from the group consisting of NaOH and NaCl or Na2SO3, fresh water, regenerated water, and steam are introduced continuously on the top of said digester
Implementation Method 2
The dissolution of noncellulosic substances from the grass-like plant feedstock is performed during the mass transfer from the top to the bottom of the said digester performed only by the gravity
Implementation Method 3
chemicals for digestion selected from the group consisting of NaOH and NaCl or Na2SO3, fresh water, regenerated water, and steam are introduced continuously on the top of said digester
Data Source
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AI summary
The present invention discloses the continuous process for production of cellulose pulp 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, disperging, diluting the cellulose pulp, screening and fractionation, concentration to remove black liquor, dilution with fresh water, yielding final cellulose pulp suitable for manufacturing of paper or cellulose sheets, and, optionally, pulp bleaching processes. The continuous digestion is performed in the vertical column at 70-100 °C for 40 minutes to 2 hours; average composition of thus formed digestion suspension is maintained within the following ranges: 0.9-1.5% w/w of NaOH; 0.15-0.4% w/w of NaCl or Na2SO3; and 15-18% w/w of grass-like plant feedstock; where concentrations of ingredients being calculated on the weight of the liquid phase. Screening and fractionation are resulting with two fractions; one being further processed by milling, and another being further processed to final pulp with or without bleaching processes. The preferred grass-like feedstock for the process is miscanthus /Miscanthus x giganteus, Andersson/.