Study On Supercritical Fluids Continuous Yarn-dyeing Process And Device

Supercritical fluid dyeing (SFD) is one of the most vigorous green dyeing in 21^st century. The general situation of the equipment and process of SFD is summarized in this paper, the parameters of SFD-Process are induced, and existing problems of SFD-Process and yarn-dyeing equipment which is the key equipment are pointed out. Concerning the existing problems, design idea of yarn-dyeing equipment is pointed out, and design method of continuous equipment of yarn-dyeing is put forward. The function of continuous supercritical fluid yarn-dyeing is complete, for it combines dyeing with cleaning. The equipment can realize not only continuous operation but also level dyeing which result in saving resource and reducing dyeing time.By summarizing and analyzing the characteristics of SFD-Process and the continuous yarn-dyeing equipment, dynamic process is determined, dyeing parameters are given out, design method of the whole device including of the circulating pump, the heater, the cooler, the tank for CO₂ and so on is pointed out, structural sizes of the equipments are given out, and strength of the equipment is checked. The dynamic process can be use of dyeing most of fabrics in market.Supercritical fluid flow through yarn packages is modeled as 2-D, axisymmetric flow through porous media, a calculated model is established for numerical simulation. Using the porous model with FLUENT software, the author simulated the inside flow-field of canister for holding yarn and found the factor that influence the flow-field of canister and determine the dimension of fluid distributor that the diameter of circular opening is 5mm and porosity is 0.6. On the basis of flow-field, the author change bobbin that composed of uniform distribution opening to the five parts bobbin of which porosity is different in axial direction. And then orthogonal test is designed, optimal opening conditions is obtained, that is, the porosity of each part is 0.5, 0.1, 0.3, 0.1 and 0.4. The whole numerical simulation effect offers a guide for the optimizing of canister structure.