Dry-Jet Wet Spinning Spinneret Dew Condensation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-density spinnerets with numerous holes in dry-jet wet spinning systems face issues with dew condensation, leading to clogging, fiber adhesion, and yarn breaks, especially during high-speed spinning or when the distance between the spinneret and coagulation bath is short, as existing methods are insufficient in preventing vapor accumulation and require costly equipment for humidity control.
Innovation Solution
A method involving a unidirectional air flow in the gas-phase portion between the spinneret and coagulation bath, with a specific air flow rate and low relative standard deviation of wind velocities, effectively suppresses dew condensation by maintaining controlled humidity and air flow, suitable for spinnerets with 2000 to 50,000 holes and a distance of less than 20 mm to the coagulation bath.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed spinning or hole multiplication is carried out to increase productivity, then fiber production efficiency is improved, but dew condensation occurs on the spinneret surface causing clogging and fiber adhesion
Solution Approach 1:
A gas-phase portion with controlled air flow is introduced as an intermediary between the spinneret and coagulation bath. This gas phase acts as a mediator that prevents direct contact between solvent vapor and the spinneret surface, thereby preventing dew condensation while allowing high-speed spinning to proceed efficiently
Solution Approach 2:
The invention changes the parameters of the gas-phase portion by controlling air flow rate (0.0008-0.0020 m³/s) and humidity (10-30% RH) to prevent dew condensation. By adjusting these parameters, the system enables high-speed spinning without the harmful effects of vapor accumulation on the spinneret surface
2Productivity
If the number of holes in the spinneret is increased to enhance productivity, then fiber production rate is improved, but solvent vapor accumulates in the gas-phase portion leading to dew condensation
Solution Approach 1:
The invention extracts and removes solvent vapor from the gas-phase portion by introducing controlled air flow that carries the vapor away from the spinneret surface. This extraction prevents vapor accumulation and subsequent dew condensation, allowing high-hole-density spinnerets to operate without causing harmful effects
3Productivity
If the distance between spinneret and coagulation bath is reduced to improve productivity, then fiber formation efficiency is improved, but dew condensation occurs more readily due to shorter gas-phase portion
Solution Approach 1:
Even with a short gas-phase portion, the controlled air flow acts as an intermediary that prevents solvent vapor from reaching the spinneret surface. This mediator function allows the gas phase to remain effective in preventing dew condensation despite the reduced distance between spinneret and coagulation bath
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 approach significantly reduces dew condensation on the spinneret, improving fiber production stability and appearance by preventing clogging and yarn breaks, enhancing productivity and maintaining fiber quality, particularly for acrylonitrile precursor fibers used in carbon fiber production.
Implementation Method 1
a gas-phase portion formed in a vertically downward direction from an extrusion surface of the spinneret to a coagulation bath liquid surface has a unidirectional air flow
Implementation Method 2
extruding, from a spinneret, a spinning dope solution containing a fiber-forming polymer dissolved in a solvent, once allowing the solution to run in air, and then guiding the solution into a coagulation bath liquid to allow coagulation
Data Source
Figure 1
AI summary
A method of producing a fiber, the method including extruding, from a spinneret 1, a spinning dope solution containing a fiber-forming polymer dissolved in a solvent, once allowing the solution to run in air, and then guiding the solution into the liquid of a coagulation bath 4 to allow coagulation, wherein a gas-phase portion formed in a vertically downward direction from an extrusion surface of the spinneret 1 to the liquid surface of the coagulation bath 4 has a unidirectional air flow, and has an air flow rate per unit time (Af) which satisfies, in relation to the amount of the solvent in the spinning dope solution per unit time (As) in the gas-phase-portion volume (Vh), the relational expression 0.0008 m3 ≤ Af/(As/Vh) ≤ 0.0015 m3. A method of producing a fiber, which, in dry-jet wet spinning, suppresses occurrence of dew condensation in the spinneret, and reduces deterioration of the appearance caused by winding on rollers in the subsequent process or by fuzzing or yarn break in the stretching process, to enable significant improvement of the productivity and the appearance as a whole, is provided.