Mixer Viscosity Control for Cellulose Dissolution
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Solution Overview
Problem
The existing methods for producing spinning solutions, particularly using NMMO as a solvent for cellulose, face challenges such as high water evaporation, increased boiling point, reduced heat transfer, and local torque loads, leading to mechanical stress and safety concerns in the dissolving process.
Innovation Solution
A method involving targeted dosage of NMMO fresh solution to optimize local load on the shaft, with additional water evaporation providing cooling, and controlled temperature management through NMMO dosage, along with monitoring viscosity and torque to extend mixing time without overheating, is implemented in a single-shaft or multi-shaft mixer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If water evaporation is increased to remove solvent, then solvent recovery is improved, but heat transfer is reduced and energy consumption increases
Solution Approach 1:
The dissolving apparatus is divided into multiple zones along its length, with different functions assigned to each zone. The first zone performs initial dissolution with lower torque load, while subsequent zones progressively increase torque to optimize dissolution at different stages, thereby improving overall energy efficiency and solvent recovery
Solution Approach 2:
Different torques are applied at different locations along the dissolving apparatus. The torque is not uniform but varies locally to match the dissolution requirements at each position, optimizing both energy efficiency and dissolution effectiveness throughout the apparatus
2Productivity
If mixing time is extended to improve dissolution, then cellulose dissolution is enhanced, but temperature increases causing overheating
Solution Approach 1:
Cooling measures are implemented in advance during the dissolution process to prevent temperature from rising too high. The cooling system is activated before overheating occurs, allowing extended mixing time without compromising temperature control
Solution Approach 2:
The system monitors temperature and torque parameters in real-time and adjusts cooling intensity and mixing speed accordingly. This feedback control allows the system to maintain optimal dissolution conditions while preventing overheating during extended mixing periods
3Productivity
If torque load is increased to enhance mixing, then dissolution performance is improved, but mechanical stress increases reducing reliability
Solution Approach 1:
The mixing process is segmented into multiple zones with progressively increasing torque loads. This staged approach allows dissolution to be enhanced without subjecting the entire system to high mechanical stress simultaneously, improving reliability while maintaining dissolution performance
Solution Approach 2:
The torque load is made dynamic rather than static, varying along the length of the dissolving apparatus to match local dissolution needs. This dynamic torque distribution optimizes dissolution performance while minimizing unnecessary mechanical stress on the system
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 enhances process control, reduces mechanical stress, and improves safety by optimizing torque load and temperature control, allowing for higher throughput and more efficient cellulose dissolution in the spinning solution production.
Implementation Method 1
the substrate dissolves in the remaining solvent or solvent mixture
Implementation Method 2
the at least one volatile solvent is at least partially evaporated
Implementation Method 3
additional water evaporation providing cooling
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for treating a mixture in a single-shaft or multi-shaft mixer (M), especially a kneader-mixer, especially for preparing a spinning solution. A solvent or solvent mixture is added to the product over the length of a product chamber in order to reduce a viscosity of the solvent or of the mixture and to increase an evaporative capacity. According to the invention, the viscosity of the solution or of the mixture is determined and/or modified in predetermined locations in the product chamber.