Combined Degassing for High-Viscosity Chitosan Spinning Solutions
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Solution Overview
Problem
Conventional degassing processes for high-viscosity chitosan spinning solutions are inefficient, leading to low production efficiency and inability to achieve industrial production due to air bubbles in the spinning solution causing filament breakage during the wet-spinning process.
Innovation Solution
A combined degassing method involving a degassing vessel with an annular feed pipe, umbrella-shaped diffusion plate, and stirring shaft with a screw propeller, utilizing vacuum conditions and shear forces to effectively remove air bubbles through separation, film-scraping, and lifting processes, ensuring complete degassing of high-viscosity chitosan spinning solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional degassing processes are used for high-viscosity chitosan spinning solution, then the process is simple, but the degassing efficiency is extremely low and production efficiency is poor
Solution Approach 1:
The degassing process is divided into multiple stages: pre-degassing (step 1), main degassing in the degassing vessel (step 2), and post-degassing filtration (step 3). Each stage uses different mechanisms (gravity settling, vacuum + mechanical agitation, filtration) to progressively remove air bubbles, transforming a single inefficient process into multiple targeted operations that collectively achieve high degassing efficiency for high-viscosity solutions
Solution Approach 2:
The patent introduces dynamic mechanical agitation through the stirring device with lifting ribs that create lifting and shear effects on the spinning solution. The stirring speed and lifting action are dynamically adjusted to match the high viscosity of the chitosan solution, enabling effective air bubble detachment and rise even in viscous conditions where conventional static degassing fails
2Manufacturing precision
If air bubbles remain in the spinning solution, then the viscosity can be maintained at required levels, but filament breakage occurs during wet-spinning causing poor product quality
Solution Approach 1:
The patent performs comprehensive degassing operations before the spinning process begins. The pre-degassing step allows air bubbles to rise naturally in the dissolution vessel, followed by intensive vacuum degassing with mechanical agitation in the degassing vessel, and final filtration through a 100-200 mesh screen. This preliminary removal of air bubbles ensures that the spinning solution is bubble-free before entering the spinneret, preventing filament breakage during wet-spinning and ensuring high fiber quality
Solution Approach 2:
The patent introduces an intermediary filtration step using a 100-200 mesh filter screen after the degassing vessel. This filter acts as a final barrier to capture any remaining air bubbles or impurities that escaped the degassing process, providing an additional layer of protection against filament breakage without significantly impacting production efficiency
3Strength
If the viscosity of spinning solution is increased to greater than 450,000 mpa·s for high-quality fibers, then dry-breaking strength and spinnability improve, but air bubbles are entrained and cannot escape during dissolution
Solution Approach 1:
The patent applies vacuum technology (pneumatics) to the degassing process, reducing the pressure in the degassing vessel to facilitate air bubble detachment and rise from the high-viscosity spinning solution. The vacuum condition lowers the partial pressure of gases, making it easier for air bubbles to form and escape from the viscous chitosan solution, overcoming the limitation imposed by high viscosity on conventional gravity-based degassing
Solution Approach 2:
The stirring device with lifting ribs creates dynamic lifting and shear effects that actively disrupt the high-viscosity spinning solution. The mechanical agitation generates forces that overcome the viscous resistance, enabling air bubbles to detach from the polymer chains and rise to the surface for removal, thereby achieving effective degassing despite the high viscosity required for quality fiber production
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 method achieves a degassing efficiency 5-7 times higher than conventional methods, allowing for the complete degassing of 6 tons of high-viscosity chitosan spinning solution within 6-8 hours, ensuring high-quality fiber production and continuous industrial operation.
Implementation Method 1
under the conditions of vacuumizing and maintaining the inner pressure of the degassing vessel to be 500-3,000 Pa
Implementation Method 2
performing continuous treatment on the spinning solution in step 2 by a combined degassing process integrating separation, film-scraping, lifting and shear
Data Source
AI summary
A combined degassing method for a high-viscosity pure-chitosan spinning solution, including: step 1, thoroughly dissolving the spinning solution in a dissolution vessel for subsequent use, the viscosity reaching 450,000-500,000 mpa·s; step 2, delivering the spinning solution in step 1 to the feed port of a degassing vessel from the dissolution vessel after filtration; step 3, in the degassing vessel, under the conditions of vacuumizing and maintaining the inner pressure of the degassing vessel to be 500-3,000 Pa, performing continuous treatment by a combined degassing process integrating separation, film-scraping, lifting and shear; and step 4, sampling at a sampling port for the detection of degassing degree, finishing the degassing operation if the detection result is eligible, otherwise repeating step (3) until the detection result is eligible. This method has high degassing efficiency and good degassing effect, and is applicable to spinning solutions of a wide range of viscosity.