Twin-Screw Extrusion for Hemp Pulp
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Solution Overview
Problem
Conventional methods for producing biosourced packaging and molded articles from plant materials like hemp often result in significant waste, energy-intensive processes, and the use of chemical additives, which are environmentally detrimental and inefficient in utilizing the entire plant.
Innovation Solution
A purely mechanical thermo-mechanical process that transforms whole hemp plants into a cellulosic pulp using a twin-screw extrusion line without chemical additives, where the hemp is humidified and processed to increase fiber length and quality, allowing for the production of a structural paste that can be molded into three-dimensional packaging units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional chemical-mechanical treatment is used to process hemp for pulp production, then the structural quality of the pulp is improved, but chemical additives are introduced causing environmental harm and waste
Solution Approach 1:
The patent replaces chemical-mechanical treatment with purely mechanical thermo-mechanical processing using a twin-screw extrusion line. The mechanical action of the screws, combined with thermal energy from heating zones, achieves fiber separation and pulp formation without chemical additives, eliminating harmful chemical effluents while maintaining pulp structural quality
Solution Approach 2:
The patent utilizes controlled temperature parameters (heating zones in the extrusion line) and mechanical parameters (screw rotation speed, compression ratio) to achieve effective fiber separation. By optimizing these physical parameters, the process achieves the same structural quality as chemical treatments but without chemical pollution
2Strength
If defibration process is used to separate long fibers from plant material, then fiber quality is improved, but significant waste is generated from core and other plant parts
Solution Approach 1:
The patent merges the processing of all hemp plant components (leaves, stems, cores, shives) into a single integrated extrusion process. Instead of separating and processing only long fibers while discarding the core, the twin-screw extrusion line mechanically processes the entire heterogeneous plant material, converting all components into useful pulp fibers
Solution Approach 2:
The extrusion line is designed to handle multiple plant components simultaneously, making the process universal for whole plant utilization. The mechanical action and thermal energy applied in the extrusion line are sufficient to process diverse materials (leaves, stems, cores) and convert them all into fibrous pulp, eliminating the need for separate defibration and waste disposal steps
3Productivity
If twin-screw extrusion line is used for continuous pulp preparation, then productivity is improved, but energy consumption increases
Solution Approach 1:
The twin-screw extrusion line operates continuously, maintaining constant mechanical action and thermal energy input throughout the material processing. This continuous operation eliminates idle time and ensures steady pulp production, improving productivity while the efficient heat transfer in the extrusion zones optimizes energy utilization
Solution Approach 2:
The patent utilizes thermal energy from heating zones in the extrusion line to soften plant materials and facilitate fiber separation. By controlling temperature parameters and heat transfer efficiency, the process reduces the additional mechanical energy required for fiber separation, thereby optimizing the overall energy consumption while maintaining high productivity
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 minimizes waste, reduces energy consumption, and effectively valorizes the entire hemp plant, producing a high-strength, stable paste suitable for molding into packaging materials without chemical effluents, thus offering an environmentally friendly and efficient solution for biosourced packaging production.
Implementation Method 1
simultaneous heating can be carried out allowing heating and/or vaporization of the water contained in pores of the (uncompacted) pieces
Implementation Method 2
simultaneous heating can be carried out allowing heating and/or vaporization of the water contained in pores of the (uncompacted) pieces
Data Source
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AI summary
The process for preparing a cellulose pulp suitable for molding uses hemp as the sole raw material. After shredding (50) the hemp straw (10), typically including the leaves, a ground raw material (1) is obtained, consisting of individual fibers and shives. The raw material is moistened, and preferably steamed, so that a moistened hemp slurry (1'), along with the fibers and shives loaded with hot water, is circulated through a twin-screw extrusion line. The mechanical processing, including extrusion (53), increases the fiber content, advantageously yielding shive fibers that are comparatively longer than the fibers already present in the ground raw material. The transformation is mechanical, meaning it is free of chemical additives. The pulp is structural, entirely bio-based, and is used for molding (58) containers or three-dimensional products.