Research On Heat Transfer Mechanism Of Large-Scale Steam Rotary Tube Dryer In PTA Drying Process

The large steam rotary tube dryer is one of the most important equipment,which produces the semi-finished products of PTA. Its capability and quality can directly affect the final products'quality. Because of the complicated heat and mass transfer process in the large steam rotary tube dryer, at present, there is still not a proper model to describe the drying process, and the research on the mechanism of heat and mass transfer is deficient. The lack of researches has restricted the development of large steam rotary tube dryer.In order to reduce the cost for producing PTA and to enhance the international competition power and domestic development, the research on the mechanism of large scale steam tube drying is necessary. This paper presents a review on the drying progress of steam rotary tube dryer in the world. On the base of research on the mechanism of heat and mass transfer in the indirect heat-transport rotary tube dryer, a suitable CFD (Calculated Fluid Dynamics) model for drying process research in the rotary steam tube dryer was established in this paper. Not only the material particle movement, concentration, velocity and temperature distribution in the dryer, but also the heat transfer coefficient of the tube surface under different structure and operation parameters condition could be simulated through the model. Compared the modeling results with the experimental data, the model has a better veracity and can provide definite basis for engineering design. On the basis of simulation, several test-beds were built, and a lot of experimentation was done. Combining examinational result, the model has been optimized. The structure and operate parameter of the rotary steam tube dryer have been optimized in using the optimize model. The model has been utilized on rotary steam dryer design. The dryer models are used in the design of many types of rotary steam tube dryers. It proved that the model have good theory guidance and application value to design of some type rotary steam tube dryer.