Dynamic Simulation Of Aromatic Hydrocarbon Extration Process In The Polyester Production

This paper is to dynamically simulate the all-process of the equipment of Aronatic Hydrocarbons Extraction. The characteristic of the technologic process is the complicated structure , numeroous components and the highly non-ideal system. The extraction tower and the recycle tower are the two typical separating equipment. This paper deeply analyses and demonstrates them, establishes a rigorous mathematical model and solves it with proper mathematical method.Dynamic simulation of multi-stage countercurrent is an important subject in the field of Chemical Dynamics. Hydrodynamics of liquid-liquid and the process of mass transfer are very complicated because the process of countercurrent extraction itself is a non-liner process .Thus we must use a non-linear model which will be solved by complicated computing method in order to establish a more practical model. This paper uses a equilibrium stage model to describe the process of liquid extraction in the extraction tower, to make reasonable simplification for the model with full consideration of axial mixing and to simplify the solving process by describing the distributing relationg of the extraction components on each stage with a simple linear relation. As to the non-linear process of the system, we calculate the constant of the Liquid-liquid equilibrium by making use of the UNIFAC Method to solve the problem of the lack of experimental data.Recycling tower is a typical non-ideal distillation tower. We regard it as N stirrers in series on each which gas fully contacts with liquid and reaches equilibrium with liquid. In flash calculation, we introduce a simplified model of gas-liquid equilibrium by applyling"two tiered approach" to quickly calculate out the constant of equilibrium throughsimplifying the alternate computation between the simplified model and the rigorous one, which guarantees the real-time and steadiness of the solution of the model.The whole simulation process is good to reflect the running conditions of equipment in the case of starting and stopping and operations under normal and abnormalconditions and react to the accidents. The simulation results not only provide foundation for operators to analyse productiong process, but also provide technic workers with referential materials to develop potential and to make further improvement.