Pack yarn dyeing, like other high-energy-consuming and high-pollution industries, regards energy conservation and emission reduction as the main goal of future development. By improving the dyeing process, improving the structural performance of dyeing equipment and optimizing the design, reducing the consumption of water, steam, electricity and dyeing materials during the processing and reducing sewage discharge is an effective way to achieve energy conservation and emission reduction.
After long-term practical application, people have mastered some parameters that have a greater impact on dyeing performance, and adopted corresponding control methods, which can not only meet the quality requirements of dyeing, but also achieve a certain level of dyeing performance. Achieve the effect of energy saving and emission reduction. For example, dyeing under small liquor ratio conditions can not only save water and steam and reduce emissions, but also improve the directness of reactive dyes, reduce dependence on salts, and reduce the consumption of salts and the content of sewage additives. Therefore, small liquor ratio is a major feature of cheese dyeing for energy saving and emission reduction.
Specific flow rate is an important parameter that affects the dyeing quality of cheese yarn. In the past, it has been believed that the larger the flow rate, the more conducive to leveling dyeing. However, practical applications in recent years have shown that this is not the case. Excessive specific flow rate consumes a lot of power of the main circulation pump, and will cause hairiness in the yarn, and even collapse the package yarn, causing a short circuit in the dye liquor circulation. In fact, in the past, the specific flow rate was increased to a large extent to make up for the lack of effective circulation of dye liquor caused by leakage. Now, people have reduced the leakage of dye liquor by improving the sealing performance of the cheese loading interface. As long as the specific flow rate actually required for cheese dyeing is provided, the dyeing quality can be completely guaranteed. If frequency conversion technology is used to control the effective circulation flow of the dye liquor and achieve synchronous dyeing, it will be more conducive to energy saving.
In addition, forced convection heating of the dye liquor can improve heat exchange efficiency and reduce steam consumption. Changing the traditional gravity discharge to pressure discharge can reduce the amount of liquid in the yarn and reduce energy consumption for washing and dehydration. Using residual hot water from indirect cooling for synchronous water washing saves both water and steam. The emergence of these functions has played a different role in energy saving and emission reduction in dyeing processing.
The process of achieving energy conservation and emission reduction in cheese dyeing is inseparable from the dyeing process and the structural performance of the dyeing equipment. Cheese dyeing has made great technological progress in the development process of the past ten years. The equipment and dyeing process are closely integrated. In addition to some parameters that affect the dyeing process, in-depth research has been conducted to find out the rules and put forward new requirements and In addition to control methods, other influencing factors related to energy conservation and emission reduction are also involved. Manufacturers have achieved certain results in dyeing applications through the optimized design of dyeing equipment structure and control, but it cannot be said to have achieved the best results, and some effects still need to be further explored and improved. Therefore, this article only briefly describes some of the most basic functions that have been applied or may be realized.
1. Optimization of dyeing process parameters
In the development of package dyeing technology, the improvement of dyeing process parameters and equipment structural performance has always played an important role. On the basis of being able to meet the yarn dyeing quality, the dyeing process parameters and equipment structural performance are continuously optimized, which greatly improves the efficiency of energy saving and emission reduction. Among them, the two most important parameters: liquor ratio and specific flow rate, are An object that dyers have been studying for many years.
1. Small liquor ratio dyeing
The traditional concept of small liquor ratio is: cheese dyeing with a liquor ratio of 1:6 is called a small liquor ratio. It must be realized under certain process and equipment conditions. In the cheese dyeing process using water as the dyeing medium, using a small liquor ratio is the most direct and effective means to achieve energy conservation and emission reduction. It not only greatly shortens and reduces the time of the dyeing process (most obviously the heating time), but also the energy consumption (water, steam, dyeing materials, etc.) and sewage discharge. Therefore, it is of great significance to dye cheese yarn with a small liquor ratio.
1.1 The role of small liquor ratio
To achieve small liquor ratio dyeing, we must understand its role and impact on the entire dyeing process and take corresponding measures to ensure it. From the perspective of practical application, the exchange frequency of dyes and auxiliaries, dye liquor and yarn is the part that produces the most obvious effect.
Reduce dyes and auxiliaries.
Equal amounts of the same dye have different concentrations in dye baths with different liquor ratios. The color with a high bath ratio is lighter, and the color with a low bath ratio is darker. If you want to dye the same shade, then a dye bath with a high liquor ratio will use more dye, and a dye bath with a low liquor ratio will use less dye. This is an objective fact. In addition to the structural characteristics of the dye, it is mainly related to the directness of the dye under different liquor ratio conditions. Experiments show that the dye uptake rate of reactive dyes will increase under low liquor ratio conditions. The amount of dye accelerator (such as salt) is related to its volume concentration (g/L). The reduction in the amount of solvent (water) also reduces the total amount of salt used and reduces the pollution caused by salt to the environment.
Many dyes need to react with fabric fibers under certain alkaline conditions. For example, reactive dyes form chemical bonds with fabric fibers under alkaline conditions and are fixed, and vat dyes form chemical bonds with fabric fibers under alkaline conditions. Restore in bath. Alkali controls the PH value of the dye bath within a certain range. A high bath ratio consumes a large amount of alkali. In contrast, a small bath ratio improves the dye uptake rate. At the same alkaline concentration F�� Points and yarn splices. This will help reduce specific flow and improve production efficiency. Of course, this places higher requirements on the performance of loose winders and dyeing machines.
5. Conclusion
Some of the above-mentioned energy-saving and emission-reducing effects of cheese dyeing are only considered from the perspective of optimized design. , not necessarily comprehensive. Energy conservation and emission reduction is a wide-ranging and complex task, especially the water-based dyeing process, which constantly turns the fresh water (a limited resource) into polluted water, which is destined to be a polluting process. Faced with this situation, we can only find other processing methods (such as supercritical CO2 dyeing) on the one hand. On the other hand, we must continuously improve the current equipment and processes to reduce energy consumption and pollution, and improve wastewater treatment. Later secondary reuse.
It can be seen that to achieve energy saving and emission reduction in cheese dyeing, the structural performance of the equipment and the dyeing process play a major role in the process stage where water is not used as the dyeing medium. Only by closely combining them with each other to optimize the design of each function or process and find out the effects of energy saving and emission reduction can the ultimate goal of energy saving and emission reduction be achieved. To this end, on the one hand, equipment manufacturers must continue to design machines with energy-saving and emission-reducing effects; on the other hand, users need to have a high degree of energy-saving and emission-reduction awareness and a strong sense of social responsibility, and eliminate those process equipment with high energy consumption and pollution as soon as possible. , actively adopt advanced technology and equipment. </p
