Optimizing Lyocell Dissolution for Versatile Applications
In recent years, the global attention towards modifying cellulose using the lyocell process has significantly increased. Nowadays, regardless of the source, raw cellulose can be obtained as a low-cost raw material and can be processed into short fibers, long filaments and films. The core of the lyocell processing technology lies in the dissolution process and the spinning step.
KaiZheng Company has optimized the cellulose dissolution technology. This technology has successfully produced high-quality spinning solutions from various low-cost raw materials, while meeting the current high safety standards.
Development and optimization
In order to enhance the application of the lyocell process, it is necessary to further optimize the dissolution step of cellulose in NMMO. The goal of the optimization is to improve the economic efficiency of the process by adopting cost-effective technologies.
The dissolution process of cellulose in NMMO takes place in the kneader. The raw cellulose and NMMO are uniformly mixed in the mixing chamber of the kneader and processed into the final cellulose spinning solution.
The key points of the dissolution technology include: using cellulose from different sources to produce a stable, high-quality and uniform spinning solution, and minimizing the formation of gels in the spinning solution to the greatest extent.
The considerable retention volume of the solvent provides sufficient buffering capacity to regulate possible process fluctuations. Therefore, the spinning solution is directly discharged from the mixer through the filter and the spinning pump. The considerable retention volume of the solvent provides sufficient buffering capacity to regulate possible process fluctuations. Therefore, the spinning solution is directly discharged from the mixer through the filter and the spinning pump.
The new development project of Kai Zheng Company aims to further enhance the technical performance. Currently, it is designing the cellulose dissolution unit for production facilities with annual capacities of 1,000 tons, 5,000 tons, 10,000 tons and 15,000 tons. The spinning solutions produced in this unit can be used as the main process for fiber production, or as the secondary process for spinning and film production.
Detailed information on cellulose dissolution technology
Kaizheng's large-capacity kneading machine demonstrates extremely high flexibility in adapting to various quality raw material cellulose processes, and is also suitable for various changes during the spinning process. Its large processing capacity can serve as a buffer tank for the spinning solution. The mixing/homogenization step, which is crucial for the preparation of cellulose slurries, can also be used simultaneously for adding additives.
Due to the high flexibility of this dissolution technology, an intermediate buffer tank can be omitted. Therefore, the filter and the spinning unit will be installed downstream of their discharge outlets. Obviously, this reduces the equipment and space requirements, thereby bringing economic benefits.
Process simulation
Kaizheng has developed a process simulation program to support the design and optimization of the process. Additionally, it can also fit the data from pilot tests and full-scale processes. By fitting and analyzing the pilot test data, the simulation can determine the optimal design scheme for the full-scale facility. Using the full-scale data, the simulation can also provide information about process flexibility and the potential of the factory.
The value of cellulose dissolution technology
Taking into account the strict process safety requirements, this technology has been optimized by selecting appropriate materials and limiting the operating temperature. As a result, it is capable of producing high-quality spinning solutions from cellulose sources almost anywhere.
