Engineering Simulation Of Melt Direct Spinning Fine Denier Polyester Filament

As an important class of differential fiber products, fine Denier and super fine denier fiber is the main development direction. In recent years, a number of high-capacity polyester melt spinning lines for producing fine denier polyester filament have been put into operation in China. But those production lines have low value-added, poor market competition and gradual declined profitability. It is very important to study the melt direct spinning process. For many data cannot got by experiments, it is feasible to analyze the process by adopting use computer simulation. This thesis focused on simulation of the melt transport process of fine denier filament, in order to provide enterprise complete simulation system of melt transport and adjusting direction of technique.Several melt transport process unit models, such as pipeline model, booster and metering pump model, melt filter model and spinning component model were established in this thesis. Based on the mechanism of melt steady flow, the computing model of melt flow time, pressure drop, temperature elevation and viscosity degradation in each unit were obtained. The changes of melt temperature, pressure and viscosity with the pipe length and flow time were simulated. It was found that the melt temperature and pressure drop at booster pump, metering pumps was changed greatly, while most of the intrinsic viscosity drop and flow time occurred at the pipeline and spinning component.In the melt transport process, the melt viscosity is mainly influenced by the initial melt intrinsic viscosity, temperature, mass flow rate and temperature of cycled heat medium. The weight factor analysis equations for the melt transportation process were fitted with different simulation conditions. For melt viscosity drop, the greatest influence factor is the initial intrinsic viscosity. Decreasing melt and cycled heat medium temperature, and increasing mass flow capacity appropriately are benefit to reduce the viscosity drop. Initial intrinsic viscosity is the biggest weight factor for the temperature rise. The high intrinsic viscosity, low melt temperature and the high cycled heat medium temperature will enlarge, the temperature raise.Based on force balance, the constitutive equation and energy balance, the single filament model was established. The differential equations of tension, temperature and spinning velocity was obtained.. According to the model, the spinning velocity, temperature, tension, fiber diameter and the velocity gradient along with the spinning line were simulated. The difference of thick denier and fine denier was compared at the same time.In the polyester filament process, product specifications and production are adjusted frequently. The influence of adjacent branch pipeline mass flow adjustment on melt quality was simulated in this thesis. It was found that melt quality will be improved with increasing production of adjacent branch pipeline. In addition, the melt transport model were verified by the data at the control point. It was found that the simulated pressure was in good agreement with actual ones, but there was some deviation for the temperature simulation.Adjusting the parameters of melt transport process, the melt quality before and after adjustment was analyzed. The melt quality such as fiber strength, strength cv, elongation, elongation cv was improved after adjustment. The Lower orientation of POY is also benefit to the processing of DTY and dyeing.