Simulation And Optimization Of EPTA Process

The main raw material of polyester production is terephthalie acid, and the development of polyester industry has promoted the development of terephthalie acid industry. In this paper, EPTA process is the research object with its process simpleness, production efficiency and low cost, Take the process a step further by using the Aspen Plus to simulate it, and it will provide a reference for practical production.This paper reviewed the research progress of p-xylene oxidation reaction mechanism and kinetics. In Aspen Plus, using RCSTR module to simulate the oxidation reactor, and the simulation is completed based on the hyperbolic kinetic model of p-xylene oxidation and side reaction dynamics model, with using salt precipitation reaction to simulate the equilibrium between dissolution and precipitation, and its results are close to the data of actual production. Dehydrating tower is essentially a rectification column, and it is simulated by using RadFrac module. The secondary oxidation reactor (i.e. the primary crystallizer) is simulated by using RCSTR module, and the secondary oxidation of the intermediate should be considered. The secondary and tertiary Crystallizers are simulated by using Crystallizer module. The filter is simulated by using Swash module. The dryer is simulated by using Flash2module. For oxidation unit, the influence of the process parameters such as reaction temperature, residence time, solvent ratio and air flow, on the oxidation reaction is inspected, put the acetic acid consumption minimum as the objective function and optimize the process parameters. For solvent dehydration unit, the influence of the process parameters such as reflux ratio, kettle liquid extraction rate and the top pressure, on separation effect and energy consumption of the dehydrator, put the total energy consumption of the dehydrator overhead condenser and bottom reboiler minimum as the objective function and optimize the process parameters. In the end, on the basis of each unit segemented simulation and the stream relationship between units, the whole process simulation of EPTA is completed, the simulation results are basically consistent with unit simulation results, and it can provide certain reference for factory production. On the basis of whole process, propose a crystallizer, being operated under the condition of optimum temperature and pressure, replaces the adiabatic two ones, and get rid of filtration&drying unit. It can reduce the risk of Crystallizer jam, the space and equipment costs. At the cost of supplying reasonable heat, it improves the product yield and quality.